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i Nuclear Materials Technology Divk.lonAnnual Review N U C LEAR MATE RIALS TECH NO LOGY



Annual Report 1992

LALP-92-41 issued: June 1992

Nuclear Materials Technology Division Mail Stop E500 Los Alamos, New Mexico 87545

LosAlamos NATIONAL LABORATORY ii ... U1 Nuclear h4ateriaLsTechnology Division Annual Rdcw CONTENTS

Foreword ...... 4

Preface Weapons Complex Reconfiguration: The Future of PlutoniumTechnology ...... 8

Overviews:Site-ReturnDisassembly ...... 13 Automationand IntegrationofSite-ReturnProcessing ...... 18 Advanced CIeaningTechnologies ...... 20 Plasma Chemical Processing ...... 26

Overviews: Advanced ManufacturingTectiolo~ ...... 34 PlutoniumCastingand Forrning ...... 38 PlutoniumDryMachining ...... 42

Overviews:NitrateRecovery ...... 44 Prm=shdyticdCheti~ ...... 49 Process MeasurementandControl ...... 52 ProcessChemishy ...... 56 SystemsIntegration...... 61

Overviews:ChlorideRecovery ...... 63 lnSitu ChlorinationofPlutonium Metal ...... 67 OpportunitiesforMagnetic SeparationApplications in Complex21 ...... 69 [email protected]...... m ...... 74 MaterialsDevelopmentforPyrochemical Applications in the Weapons Complex Reconfiguration ...... 78 PyrochemicalINtegratedActinideChlorideLine (PINACL) ...... 82

Overviews:Waste Management...... 85 DestructionofHazardousWastesby SuperCritical WaterOxidation ...... 87 Waste StreamMonitoring...... 99 WasteTreatmentiChelatingPolymers forRemovalof Heavy MetalsfromAqueous WasteS&em ...... 101

contentscontinuedonnext page

Contents 1 CONTENTS

Group Profiles ...... 107 Nuclear MaterialsTechnologyDivisionOrgtition Chart ...... 108 NuclearMaterialsTechnologyDivision ...... 109 Nuclear Fuels Technology ...... 110 Nuclear MaterialsProcessing:NitrateSystems...... 112 NuclearMaterialsProcessing:ChlorideSystems...... 114 Nuclear MaterialsMeasurementand Accountability...... 116 PlutoniumMetallurgy ...... 117 ActinideMaterialsChemistry ...... 119 Nuclear MaterialsManagement...... 120 TA-55 FacilitiesManagement...... 121 Heat SourceTechnology ...... 122

Awards, Honors, and Patents ...... 123

Publications...... 127 NuclearFuels Technology ...... 128 Nuclear MaterialsProcessing:NitrateSystems...... 129 Nuclear MaterialsProcessing:ChlorideSystems...... 130 Nuclear MaterialsMeasurementand Accountability...... 134 PlutoniumMetallurgy ...... 134 Actinide MaterialsChemistry ...... 136 NuclearMaterialsManagement...... 140 Heat SourceTechnology ...... 141

Credits...... 143

2 Nuclear h4aterialsTdnology Divtslon Annual RAw F o R E w o R D FOREWORD

+ - -. .. -“\l s —..*Y . . “+ +-J s ~ ~ ‘)1 Division Leader by Delbert R. Harbur ‘?. Delbert R. Harbur

Most of the nuclear materi- To remain at the forefront In the national defense arena, als activities at the Los Alamos of important areas of actinide we support nuclear weapon National Laboratory are done and materials science, design, development, and test- in the Nuclear Materials Tech- we maintain a strong and vital ing programs by developing nology Division. The Division base of scientific research. Our safe, efficient, and environmen- is responsible for the Plutonium materials research is directed tally acceptable technologies for Facility located at Technical at understanding the relation- manufacturing and processing Area 55 (TA-55). With our ships among processing, compo- of plutonium in the nation’s expert research and develop- sition, structure and properties production complex. In addition, ment in the fields of metallurgy, of materials and ultimately at the division’s energy programs chemistry, engineering, and discovering how these materials focus on nuclear reactors for solid state physics, we examine respond to external environ- space power and radioisotope the complex chemistry associ- ments. Our chemical processing heat sources. ated with plutonium and other research is aimed at understand- The Laboratory’s technology actinides in various physical ing the basic chemistry involved leadership role for the nation’s states. together with the complex plutonium production complex interactions found in real has been well established over systems. the last decade. Rapid, signifi- cant changes in world events and within the nation’s weapons production complex indicate a strengthening of this role. The nation’s nuclear materials pro- duction complex is widely perceived as at the end of its useful life and as no longer sized nor technologically equipped to meet future needs.

4 Nuclear Materials Technology Division hnuai Rdcw “Technologiesthat we researchedand demonstratedas prototypesat TA-55willmakeup thebasetechnologiesfor the futurePlutoniumManufacturingPlantin the Wmpons ComplexReconfiguration(Complex21).”

For the last decade, we have Technologies that we re- This year focuses on the been upgrading the manufactur- searched and demonstrated as processing technologies that we ing and processing technologies prototypes at TA-55 will make have developed for Complex 21. developed at TA-55 to meet the up the base technologies for the Most of these technologies are proessing need to decommission future Plutonium Manufacturing quite mature, and the associated and decontaminate older facili- Plant in the Weapons Complex metallurgy and chemistry are ties and to reconfigure the Reconfiguration (Complex 21). well understood. We are now weapons complex into properly Fortunately, many of these emphasizing process integration, equipped facilities for their technologies will also be the real-time sensors, and process- future missions. Using the ones required to decommission control systems. Automation is Laboratory’s strong research and older facilities and to stabilize applied only to mature, fully- development base, we initiated residues. integrated, and optimized these upgrades to address prob- process systems. lems inherent in the inability of This publication provides a the older technologies to prop- brief review of the scientific and erly deal with the growth of technical activities in each of our regulatory, compliance, and operating groups, as well as a waste issues confronting the compilation of our accomplish- Department of Energy. ments during the past 18 months, including awards, patents, and publications. +

Fomwod 5 6 Nuclear Materials Technology Division Annual Rcvlew


Weapons Complex Reconfiguration: The Future of Plutonium Technology by Dana C. Christensen

Deputy Division Leader Dana C. Christensen

Weapons Complex As to the existing production Finally, the future production Reconfiguration Concerns and supply infrastructure, the and supply infrastructure re- Recent unforeseen changes in nation currently owns a signifi- quires technical support for the the global balance of power have cant quantity of plutonium; it stockpile (at whatever level it prompted a reevaluation of the exists in the form of weapon finally reaches), the capability to entire nuclear weapons complex, components, oxides and metals, fabricate improved components including research and develop- miscellaneous lean residues, and and upgrades of the stockpile, ment in the area of nuclear contaminated equipment. How- and the means to survey the materials technology. National ever, most of the production stored inventory of material to defense concerns related specifi- facilities are more than 35 years ensure accountability and safety. cally to plutonium processing old and have reached the end of The primary concern will con- include their useful lives. tinue to be the minimization of Of utmost concern is manag- hazardous waste and the manage- s stockpile security and ing the plutonium supply so as to ment of necessary waste so as to surety, avoid environmental contamina- preclude release to the environ- ● existing production and tion and to prevent loss of mate- ment. Future facilities must supply infrastructure, and rial to a proliferant group. We formalize operations in compli- ● future production and must have available safe, secure ance with increasingly stringent supply infrastmcture. facilities in which to store the federal requirements, thereby material returned from stockpile providing a high degree of safety In the area of stockpile secu- disassembly activities as well as to employees, the public, and the rity and surety, we must main- the material recovered from environment. tain a safe but robust arsenal of residues. The mandated shrink- nuclear weapons while reducing ing stockpile and the reduced The Los Alamos Plutonium the numbers of various types of reliance on the nuclear deterrent Facility weapons. Constant surveillance as a key to national defense mean The successful reconfiguration of stockpile components and that our excess and aging facili- of the nuclear weapons complex materials is essential to ensure ties must be decontaminated and requires that the above key areas that devices will work when decommissioned. Existing envi- be addressed. Although some called upon and that they will ronmental damage resulting technical developments at Los remain in a safe and secure from the activities conducted in Alamos uniquely address only condition until that time. these facilities must also be one area, many others contribute ameliorated.

8 Nuclear Materials Technology DivMon Annual Rcvlcw Fig. 1. Baseline flow sheet for the Plutonium Processing Facility for the Returns‘i’e+=)-(==k’r:::ctreconfigured weapons complex.

This emphasis on advanced @-@ technology, including the suc- cessful demonstration of pluto- nium production, ensures that the Los Alamos Plutonium Facility will continue to refine the technologies of the 1990s as it plans the developments of the 2000s. I Baseline Flow Sheet for Disposal Plutonium Processing Pivotal to selecting the appro- priate development activities is to all three areas. The perva- For more than a decade, the the effective charting of a direc- sively multidisciplinary nature mission of plutonium operations tion that ensures progress by of the Laboratory makes it at Los Alamos has included setting a defined goal. All of our uniquely suited to address activities focus on the plutonium the entire spectrum of con- ● conduct of fundamental processing facility of the future. cerns associated with the and Fig. 1, a baseline flow sheet for reconfiguration of the nuclear applied research, that facility, highlights the key weapons complex. The ● development of advanced technical areas of emphasis for Laboratory’s formula for processes, processing and, in addition, continued success comprises ● full-scale demonstration of identifies technology develop- an educated and experienced those processes in a ments needed for the enthe staff possessing detailed knowl- plutonium environment, complex reconfiguration. edge of the important issues and and specially designed equip- ● exchange of technology ment and facilities unparalleled with other DOE contractors throughout the world. and industry. Weapons Complex Reconfiguration: The Future of Plutonium Technology (continued)

Improvements designated as Because no acceptable technology Improvements in this area applicable to the future pluto- for performing this task presently will also significantly reduce nium complex will assist in exists, the successful integration the amount of residues and the meeting existing cleanup re- of site-return operations at Los quantity of plutonium in resi- quirements as well as facilitate Alamos will be a landmark dues, thereby reducing the need the management of future achievement. Further, the waste for aqueous recovery. The major material inventories. The five generated in this fully integrated goals in the manufacturing area chapters in this section provide approach is near zero. Develop- center on maximizing the utili- detailed attributes of projects as ments in this area will apply zation efficiency of plutonium they apply to the Fig. 1 flow directly to needs in stockpile metal and on minimizing the sheet. security and surety and future generation of residues and production and supply infra- waste. Developments in n~anu- Site Return Processing structure. facturing will directly impact The chapter on site return stockpile surety and future processing provides details of Advanced Manufacturing production and supply infra- the problems being addressed Technology structure. and of a new suite of technolo- The chapter on advanced gies being implemented as manufacturing technology Nitrate Recovery and Chloride solutions. The processing ap- addresses significant changes Recovery proach is elegantly simple but in techniques for fabricating The chapters on nitrate involves the integration of a weapon components while recovery and chloride recovery number of processing steps, minimizing waste and promoting address the aqueous recovery of each of which uses unique and safety. Plutonium manufacturing residues resulting from the site- different chemistries. The goal processes, which require the use return- processing and manufac- of this work is to demonstrate of chlorinated and fluorinated turing functions. The recovery that complex site-return process- hydrocarbons, has historically operations generally involve the ing operations can be integrated been responsible for the produc- dissolution of residues in acids, into a flow loop in which safety, tion of mixed waste; however, the separation and purification accountability, and processing new operations now under of plutonium, and the conver- complement each other. development will eliminate the sion of the plutonium into problem of mixed waste. foundry-acceptable metal.

10 Nuclear Materials Techrwlogy Division Annual Review “The overall goal of Complex 21 is ‘zerodischarge,’ that is, no release of plutonium to the environmerit.”

The bane of aqueous systems has In particular, the existing residue The important types of waste been the volume of waste and waste inventory is not now that must be managed include and sludges generated. The goal capable of being packaged for liquids, sludges from of recent developments in the long-term storage. Technologies treatment, combustibles, plastics process control area is to operate in nitrate and chloride recovery (especially polyvinyl chlorides), the process chemistries as closely will provide the basis for devel- stack , and various solids, as possible to the stoichiometric oping processing and packaging such as tools, glove boxes, and limits, thereby minimizing the techniques for long-term storage process equipment. need for excess reagents and of residues. The overall goal of Complex ultimately reducing the volume 21 is “zero discharge,” that is, of waste. Scientists are also Waste Management no release of plutonium to the developing element- or non- The final chapter covers waste environment. The extent to selective systems capable of management. The essential which that goal can be met is plucking plutonium out of a focus of all nuclear materials a measure of our success in scrap matrix without the help processing is the minimization this key area of operations. of reagents. Finally, a key goal or elimination of waste wherever Los Alamos has addressed this of nitrate and chloride reco~ery possible. Although not all waste goal by consistently subscribing operations is to demonstrate can be eliminated, the goal in to a very direct and logical process integration in an envi- waste management is either to approach to waste processing: ronment where the synergism of remove all activity before dis- 1. Identify the problem and unit operations can be measured. charge or to immobilize the develop an approach for solving The work described in these two waste so as to preclude any it that begins at the initial stages chapters will have a profound uncontrolled release. To the of all related processes. impact on all aspects of future extent possible, reagents as well 2. Identify and understand plutonium processing. as any recovered plutonium will the related fundamental chemis- be reconstituted and recycled. try and metallurgy. 3. Develop process control mechanisms such as sensors.

Preface 11 Weapons Complex Reconfiguration: The Future of Plutonium Technology (continued)

4. Engineer processing equip- The Role of the Nuclear Materi- ment to meet process and pro- als Technology Division cess control requirements and In conclusion, the Los Alamos constraints. Plutonium Facility is an un- 5. Adapt engineered equip- equaled national resource be- ment to facility operating con- cause it is the only site that hosts straints, or, in the case of a new technologies covering the entire facility, engineer the facility spectrum of plutonium needs. around processing requirements The Nuclear Materials Technol- and constraints. ogy Division is responsible for Experience shows that when applying this capability to meet process engineering precedes a weapon complex reconfiguration clear understanding of the requirements and to respond to problem or of the process chem- changing needs in a manner that istry involved, failure is certain. adheres to the premise of safe Projects can be successfully conduct of operations and full brought to fruition only when compliance with regulatory knowledge precedes action. requirements. + A unique strength of research, development, and demonstra- tion activities at the Los Alamos Plutonium Facility is that they follow the five-step logical approach in a healthy range of activities.

12 Nuclear Matdals Technology Dwision Annual Rmlew SITE-RETURN PROCESSING

Site-Return Processing Overview by John Haschke Plutonium Metallurgy Group

Scope and Options mechanical operations are Only two chemical processing Because nuclear reactors are concerned with converting options, aqueous recovery and unlikely to be operated for the plutonium-containing compo- pyrochemical purification, are purpose of producing additional nents into a form suitable for sufficiently developed to merit supplies of plutonium, the only chemical reprocessing. The serious consideration as baseline remaining somce of plutonium chemical operations include a flow sheet technologies for metal for future weapons fabri- sequence of process steps that plutonium recovery. Alternative cation is site-return components. produce purified metal for use purification methods, such as Consequently, site-return pro- in fabricating new components. fractional of the cessing is the key element of the Selection of the best process halides, are viewed as competing flow sheet for the plutonium technologies is of utmost impor- options that must be adequately processing facility for Complex tance. All baseline technologies demonstrated and evaluated 21 (see the introductory article) should be adequately demon- with regard to flow sheet impact because all metal entering the strated and should reflect state- before serious consideration as facility will be subject to such of-the-art technology. In contrast an alternative to the two proven processing. The objective of site- to the well-established process processes. return processing is to produce for mechanical operations, Aqueous and pyrochemical required quantities of War several process alternatives are methods represent substantially Reserve metal from site-return proposed for chemical opera- different purification options. feed materials while minimizing tions. The selection of baseline Aqueous processing, the more waste generation and worker methods for chemical processing traditional approach, requires radiation exposures and maxi- of plutonium-bearing materials several steps. The plutonium- mizing safety and efficiency. isa somewhat controversial bearing metal is first dissolved Site-return processing incor- issue, complicated by the fact in aqueous nitric acid, and the porates both mechanical and that the initial chemical opera- plutonium is then separated chemical operations. The initial tion fol-lowing mechanical from impurities by ion exchange mechanical operation is disas- operations largely determines or extraction methods. sembly of site-return units into the structure of the entire flow basic components; subsequent sheet.

Site Return Processing 13

— Site-Return Processing Overview (continued)

Plutonium is removed from the Pyrochemical purification has The advantages of the purified solution by precipita- been adopted as the baseline pyrochemical method are real- tion, and metal is regenerated recovery process because the ized in reduced waste generation by calcium reduction of the combination of purification and and in a high single-pass process oxide or . All residues support technologies is consid- efficiency. A comparable single- are redissolved for recycle ered superior to the technologies pass efficiency is realized in through the process. for aqueous nitrate recovery. aqueous nitrate recovery, but In contrast, pyrochemical Important considerations in the that operation requires several purification is a two-step ap- selection of the baseline process steps and is significantly less proach in which the plutonium incIude the quantity of waste cost-effective and energy effi- retains its metallic form through- generated, the level of radiation cient than pyrochemistry be- out the process. Molten salt exposure, the complexity and cause a chemical reduction step extraction to remove americium cost of equipment, and the is required to regenerate the is followed by electrorefining to process efficiency. Although metal. Incorporation of aqueous eliminate other impurities. such issues are best addressed chloride and nitrate facilities Because both of these for the respective flow-sheet with pyrochemical methods can pyrochemical processes use options using available data and be viewed as advantageous molten metal chlorides as sol- process modeling, certain key because it provides a balanced vents, the reprocessing of their issues merit brief consideration. capability for handling the many residues requires that an aque- The main disadvantage of the types of residues stored for ous chloride facility be provided aqueous process is the genera- recovery and accommodates the in addition to the aqueous tion of large amounts of waste. flexibility needed to exploit the nitrate facility used for repro- The use of aqueous nitrate and waste-stream polishing potential cessing oxide residues. chloride facilities to support of aqueous methods. pyrochemical operations would bean unnecessary duplication of capability.

14 Nuclear MatddsTcchnolagy Dividon Annual Rdew “The baselineflow sheet provides a basisfor formulating relevant research and development strategies and for effectively directing resources to support the most promising options.”

The baseline flow sheet changes the facility footprint nor The baseline decontamination provides a basis for formulating significantly alters equipment process is a demonstrated relevant research and develop- design. Baseline improvements manual operation in which dilute ment strategies and for effec- can be accommodated at a point nitric acid solution and abrasion tively directing resources to well beyond the date for final are used to remove plutonium support the most promising process definition and they oxide particles from uranium options. As implied in the guarantee that a usable process surfaces. The process generates preceding discussion, two will always be available for large volumes of liquid waste categories of effort are recog- implementation. that must be treated by a cur- nized: efforts to modify the rently undefined method. baseline process and efforts to Baseline Processes provide alternatives to it. Disassembly Consolidation A decision to pursue an activity The baseline process for A baseline method for con- falling in the second category component disassembly incorpo- solidating plutonium compo- must weigh the potential rates standard precision machin- nents also remains undefined. payback from the alternative ing techniques. The need for Demonstrated alternatives method against its complexity residue reprocessing is avoided include compaction, casting, and development time and because precision methods are and in-process fusion of against its impact (positive or capable of selectively removing component fragments. negative) on the flow sheet and materials without including on facility design. Although turnings from adjacent compo- Molten Salt Extraction pursuit of promising alternatives nents. Further development is Molten salt extraction is the is necessary, allocation of limited not needed. baseline process for removing resources to enhancing baseline The decontamination of en- americium-241 from aged pluto- technologies seems most pru- riched uranium components is nium metal. Ingrowth of the dent because modification of a an ancillary disassembly process. americium isotope from beta baseline technology neither Plutonium-containing particles decay of plutonium-241 (half-life must be removed from a compo- of 13.2 years) present in the nent before it can be returned to original metal presents a signifi- the uranium reprocessing facility. cant radiation hazard for workers handling aged metal.

Site Return Processing 15 Site-Return Processing Overview (continued)

Americium-241 (half-life of 458 The production of plutonium load for the aqueous chloride years) undergoes alpha decay, trichloride reagent for molten salt facility. However, only a portion but a large fraction of the process extraction and electrorefining is of the site-return metal must be forms an excited-state nep- an essential support operation of purified by electrorefining; War tunium-237 daughter that emits the site-return flow sheet. The Reserve metal is obtained by a penetrating 60-kiloelectron- baseline process is a demon- blending the high-purity product volt gamma ray. The maximum strated technology that involves with americium-free metal from activity of aged metal is reached preparation of plutonium hy- molten salt extraction. after approximately 75 years. dride. The hydride is subse- Immediate separation of ameri- quently converted to plutonium BaseIine Modifications and cium is essential for reducing trichlondeby reaction with Alternatives radiation exposures. gaseous hydrogen chloride at The baseline site-return Americium is extracted into a elevated temperatures. processes provide several molten salt that is physi- opportunities for modification cally separated from the ameri- Electrorefining and substitution. Such efforts cium-free metal in a subsequent Electrorefining is the baseline include the development of breakout step. When plutonium process for producing high- reusable crucibIes for various trichloride is added to a molten purity plutonium. The technique pyrochemical applications and calcium dichloride phase that is uses molten calcium dichloride several larger development in contact with molten pluto- rich in plutonium trichloride as activities that have potential nium, americium in the metal is a transport medium for an elec- for significantly upgrading exchanged for plutonium in the trolysis process that removes processes. salt by an ensuing reac- plutonium from an impure tion. Although molten salt plutonium anode and deposits extraction is an established pure metal at a second electrode. production method, significant The anode residues constitute a upgrades are possible. major portion of the reprocessing

16 Nuclear MaMialsTechnology D1vMon Annual Re\5ew “’’s-o-e-p’:;”

Plutonium Processing Facility

Fi!&6iz!z!i!iEI + I ’’’’;’J0ns

\ I


An in situ chlorination The use of a -rich Automation process for use in molten salt plasma as an alternative method An important and unifying extraction and electrorefining for decontaminating uranium initiative of site-return activities is one of the larger activities components is also being investi- is their automation and integra- being pursued. Plutonium gated. Fluorine atoms generated tion, as detailed here in a sepa- trichloride is generated within from inert fluorocarbons in a rate article. Although this con- the pyrochemical apparatus radio-frequency field react with cept is not indicated on the by bubbJ.inga stoichiometric particles contaminated with baseline flow sheet, consolidat- amount of chlorine into plutonium oxide to form gaseous ing operations are expected to the molten metal. The potential that is reduce radiation exposures, payback is large because process collected in a downstream trap. enhance safety, and increase operations are simplified and The technology will replace the efficiency. Negative impact on the need for a facility to prepare acid decontamination process the flow sheet is not introduced plutonium dihydnde and with a method that produces because the approach being plutonium trichlorideis elimi- minimal solid residue. This developed does not alter the nated. Application of the tech- replacement will eliminate the fundamental chemistry of the nique has been demonstrated need for a Ieachate treatment baseline process; the effort for molten salt extraction. A facility and will not negatively attempts only to exploit op- detailed description of the effort affect the flow sheet because portunities that currently exist. is included in the chapter on decontamination is a terminal In addition to accomplishing chloride recovery operations. flow-sheet process. The condi- improvements cited above, tions and kinetics for etching the automation and integration plutonium oxide have already program will provide a unique been defined.” A detailed report and necessary opportunity for on plasma processing is included unifying individual technologies in this chapter. and demonstrating their chemi- cal and process compatibility before final flow sheet definition. + *J. C. Martz, D. W. Hess, J. M. Haschke, J. W. Ward, and B. F. Flamm, “Demonstration of Plutonium Etching in a CFd/OzRF Glow Dis- charge,” ]. NucZ.Mater. 182,277 (1991).

Site Return Processing 17 SITE-RETURN PROCESSING Automation and Integration of Site-Return Processing

Joseph C. Martz and John M. Haschke Plutonium Metallurgy Group Tony J. Beugelsdjik and Lawrence E. Bronisz Mechanical and Electronic Instrumentation Group

Thenext-generaticm nuclear The component forms the input Reconfiguration of the materials processing complex to the process. Exit streams nuclear weapons complex will require new technologies include nonnuclear component provides a unique opportunity to dismantle site-return compo- materials, salt from the purifica- to apply the concepts of concur- nents and recover the nuclear tion step, and nuclear material rent engineering to site-return materials. By integrating in a form suitable for long-term disassembly. In the past, auto- baseline technologies with storage or immediate reuse. mation technologies—usually proven techniques in robotics Added reagents include stoichio- involving the application of and automation, we can create rnetric quantities of oxidant for commercial equipment in a a safe, environmentally friendly removal of americium and glove-box enviornment—have operation that will eliminate calcium dichloride for been applied to preexisting mixed wastes, reduce waste pyrochemical operations. processes and process equip- generation to theoretical mini- The high radiation levels ment with mixed results. mums, reduce personnel radia- resulting from americium build- Los Alamos has been involved tion exposure to as low as rea- up in the weapons stockpile in developing automated tech- sonably achievable, and place make remote handling highly nologies for almost a decade. process safety above all other desirable for site-return material. This extensive experience has operational concerns. A second- Specifically, the high-radiation- led to the identification of the ary objective of this technology exposure operation of salt important issues that influence development is to maximize breakout after molten salt extrac- glove-box automation. Thus, process efficiency. tion can be automated to reduce Los Alamos expertise, combined The three key processes in worker exposures. In addition, with knowledge of the important the site-return operation are the pyrochemical methods process chemistries, has led to disassembly of the weapon envisioned for site-return pro- the development of a system component, recovery of its cessing are amenable to automa- requirements document that nuclear material, and purifica- tion. Increases in process safety outIines the key issues and tion of the recovered metal to and efficiency are an added technologies involved in the meet War Reserve specifications. benefit of system integration. successful implementation of an automated site-return processing system. Engineering analysis

18 Nuclear MakvialsTcdmology Division Annual Review “ By integratingbaselinetechnologieswithproventechniques in roboticsandautomation,we can createa safe,environmentally friendlyoperationthatwill eliminatemixedwastes,reducewaste generationto theoreticalminimums,reducepersonnelradiation exposuretoas lowas reasonablyachievableand placeprocess safetyaboveall otheroperationalconcerns.”

and design are currently in Certain assemblies require A single glove box accommo- progress. Individual process consolidation before material dates all process operations. A technologies have matured over purification. An intelligent centrally located parting system the past several years so that station is used to perform this separates intact assemblies into they are now amenable to inte- task. This modular approach hemishells. The automated gration and process automation. follows closely the development material-handling system trans- Separation of site-return of automated chemical analysis ports individual hemishells to components is accomplished technologies for the Department the chemical recovery and through the use of intelligent of Energy’s Office of Environ- purification operations. A single modules optimized to perform mental Restoration and Waste parting and material transport this task. A specially designed Management. Software architec- system serves two separate parting system consisting of a ture and control structures recovery stations. parting lathe and custom tooling already in place allow a facile The changing culture in the receives the intact pit. Design and rapid development effort. Department of Energy with of the parting system addresses In the purification stages of respect to environmental and such typical glove-box opera- the site-return system, intelligent safety awareness demands that tional issues as maintenance stations perform the requisite all new operations generate within the inert atmosphere, process chemistry. Fixed auto- minimal wastes, avoid mixing reliability of components, acces- mation stations provide repeat- different types of waste, mini- sibility for routine service, and able process control that enables mize personnel radiation expo- optimum use of glove-box space. automation of highly repetitive sure, and operate to the highest Important features of the system process operations. The automa- standards of safety and security. include modular x- and y-axes, tion system provides a means of The automated site-return a telescoping z-axis, externally transport between these stations. processing system described mounted electronics, and dust- Individual processes are coordi- here meets these requirements proof construction. The intent nated to the extent that the while ensuring high process of this effort is to develop a product from one operation efficiency. + flexible, modular handling provides the feed for the next. system in partnership with In addition, each chemical private industry. operation will be optimized such that its by-products will not negatively impact subse- quent process operations.

Site Return Processing 19 SITE-RETURN PROCESSING Advanced Technologies by John M. Haschke Plutonium Metallurgy Group

Introduction These chlorocarbon safety, and health requirements, Plutonium components are (which deplete ozone, pose a suitable alternative technologies exposed to a variety of organic carcinogenic hazard, and gener- must not generate mixed waste, compounds during fabrication. ate mixed waste) are subject to must be economically feasibIe In normal production practice, a regulation limiting their contin- and process compatible, and protective flow of hydrocarbon ued use and availability. During must satisfy requirements for oil is directed over a part during recent production cycles, the component cleanliness. Al- machining. Residual oil must be combined annual usage of these though the levels of cleanliness removed by an in-process clean- chlorocarbons has approached achieved by the existing TCA- ing procedure to facilitate han- 100,000 liters, a large part of based process are unknown, the dling and inspection of a part. which is released as atmospheric maximum allowable level of During these operations a emissions. hydrocarbon residue calculated component is exposed to other Although anticipated from evaluation of data from organics that are removed by decreases in weapons produc- stockpile systems is 5 micro- a final cleaning procedure tion wilI result in substantial grams per square centimeter of immediately before assembly. reductions in solvent usage, component surface area. Hydrocarbon residues remain- chlorocarbon-based processes Results of joint development ing on plutonium surfaces are must be eliminated. The use of efforts with collaborators from radiolytically decomposed dry machining techniques EG&G Rocky Flats are presented during stockpile storage of precludes the need for in-process here. Technologies based on weapon assemblies,and cause cleaning. However, final clean- (SCF) carbon detrimental corrosion of nuclear ing is necessary because compo- dioxide and on aqueous media components. nents are exposed to oils and are described along with efforts As in many other established other hydrocarbons during to establish analytical methods manufacturing processes, subsequent manufacturing for defining surface cleanliness. chlorocarbon solvents are used operations. Advanced cleaning A third cleaning alternative to degrease plutonium compo- techniques are being investi- based on plasma processing is nents. The in-process operation gated to identify and develop described in the article titled uses a carbon tetrachloride spray environmentally acceptable “Plasma Chemical Processing.” rinse, and an ultrasonic clean- alternatives to chlorocarbon- ing/vapor decreasing method. based methods. In addition to A 111-trichloroethane (TCA) satisfying all environmental, soIvent is used for finaI cleaning.

20 Nuclear h4aterialsTcchnoIogy Oividon Annual Review “Advanced cleaning techniques are being investigated to identify and develop environmentally acceptable alternatives to chlorocarbon-based methods.”

Baseline Cleaning Process occurs naturally, steel and uranium surfaces after Unlike most baseline tech- is nontoxic and unreactive, and cleaning with carbon dioxide nologies in the flow sheet for the poses minimaI risk to the envi- and with TCA.1 Tests conducted Complex 21 Plutonium Process- ronment and to the health and at a vendor laboratory show that ing Facility, the process for final safety of employees and the 20-centimeter-diameter steel cleaning of plutonium compo- public. Supercritical conditions hemispheres are cleaned to nents has not been demonstrated are attained at modest conditions levels well below the limit for for production. Use of SCF (above 31°C and 74 bar pres- plutonium at reasonable tem- carbon dioxide is recommended sure), and the high volatility of peratures, pressures, flow rates, because of its potential cleaning carbon dioxide facilitates the and times.2 These studies, which capability and its anticipated separation of solvent and solute. are consistent with earlier extrac- process compatibility. However, SCF carbon dioxide technology tion work showing that the because pursuit of a single is well developed and widely solvent properties of SCF carbon alternative technology for used for extracting organics in dioxide are strongly dependent replacing the chlorocarbon the food, , pharmaceuti- on solvent density, establish cleaning method is imprudent, cal, and synthetic-fuel industries. tentative conditions for cleaning the cleaning potential of aqueous Large SCF systems are commer- (temperature of 35°C to 400C and media is also being investigated. cially available. pressure of 150 to 200 bars). At Prior work suggests that SCF these conditions, the fluid den- Supercritical Fluid Cleaning carbon dioxide is an effective sity is in the range of 0.80 to 0.85 Background cleaning medium. Results of grams per cubic centimeter. Supercritical carbon dioxide initial studies of SCF cleaning Cleaning times for hemispheres is the primary candidate for conducted at Rocky Flats show are less than 20 minutes at a replacing TCA in the final that comparable levels of carbon- fluid flow of 1.0 Iiter per minute. cleaning of plutonium compo- containing residues remain on nents. A recycle SCF carbon dioxide process satisfies both the Ietter and the spirit of environmental regulation.

Site Return Processing 21 Advanced Cleaning Technologies (continued)

Fig. 1. Dirzgrmnof n closed-loop SCF GloveBox cleaning system. ~re~~ureTemperature m

L Concept II , 1 The concept of an SCF Heated Expansion carbon dioxide cleaning Valve apparatus is illustrated in ((~)] C02 Fig. 1. The part is contained C02 supply Residue- in a heated cleaning cham- Collection Collector ber with a clearance of 2 to 3 t Vessel . millimeters on each side of the part to minimize fluid u JI volume and to direct flow IF?!!+——MechanicalorThermalCompression_ over the part surface. Liquid carbon dioxide is drawn from the supply, pumped to the desired pressure, and heated to the desired temperature in the Several advantages of the Stcitzls supercritical range before flow- concept are evident. In addition A laboratory-scale SCF ing over the part at a controlled to using a solvent posing mini- system has been constructed and rate. Organic residues dissolve mal risk, the process concen- installed. In this system, an air- in the solvent phase and are trates all cleaning residues for driven pump delivers 18 millili- carried out of the chamber and disposal or processing. If in-line ters of solvent per minute at a through a heated expansion filters do not remove plutonium- density of 0.85 grams per cubic valve. The decrease in density containing particles entrained by centimeter through a 20-cubic- accompanying expansion forces the fluid stream, they also will centimeter cleaning chamber. dissolved organics to precipitate collect with the residue. The Parallel chambers are installed in a collection trap. The carbon recycle potential of the process is inside a glove box for plutonium dioxide is condensed and re- particularly attractive; no wastes studies and outside the glove cycled to the supply vessel. or emissions are produced other box for nonnuclear samples. Important cleaning parameters than the concentrated organic Sample surface areas up to 50 such as temperature, pressure, residue. square centimeters are accom- flow rate, and time are readiIy modated by these chambers. controlled.

22 Nuclear Materials Technology Cividon Annual Rdcw “The recycle potential of the process is particularly attractive; no wastes or emissions are produced other than the concentrated organic residue.”

Important compatibility of water whose chemical nature The results will be used to define issues are resolved by initial is unknown. If it exists as car- specifications for a pilot-scale studies with plutonium. Al- bonic acid, plutonium may SCF system. The effects of the though the reaction of pluto- dissolve and cause dimensional cleaning process on the chemis- nium with carbon dioxide to changes in the component and try and storage behavior of the form plutonium dioxide is contamination of the equipment. metal must also be determined. thermodynamically favorable Visual observation of the surface, A pilot system will establish and highly exothermic, reaction mass gain data, and downstream the cleaning parameters for a is not anticipated because of contamination surveys show that production process. Procure- slow kinetics.3 Numerous a l-hour exposure of clean metal ment and installation of com- chemical compatibility tests to static SCF carbon dioxide mercial equipment is planned. conducted within the projected containing 0.13 mass percent Experiments will be conducted cleaning range show that bur- water resulted in formation of to define cleaning parameters for nished plutonium remains a passive surface film. full-sized parts, develop solvent untarnished after exposure to Cleaning studies with SCF recycle methods, and address SCF carbon dioxide for several carbon dioxide are in progress. safety issues. hours. The metal also shows no Attempts to use gravimetric evidence of reaction with the methods for quantifying residual Aqueous Cleaning solvent after one hour at extreme levels of hydrocarbon oil on Background conditions of 100”Cand a pres- cleaned samples show that such Aqueous cleaning methods sure of 310 bars. techniques are not sufficiently provide an alternative to the The effects of water contami- sensitive. An infrared spectro- baseline SCF carbon dioxide nation in the solvent are also scopic method of analysis is process. The environmental, established. The volubility limit necessary to establish cleaning safety, and health risk is low, but of water in SCF carbon dioxide efficacy. Future experiments will the compatibility of an aqueous at 40”C is approximately 0.5 investigate effects of such param- system with the plutonium mass percent. Although com- eters as temperature, pressure, recovery process is uncertain. mercial carbon dioxide contains flow rate, time, and residue type water at ppm levels, the flow in order to identify the optimal procedure exposes the pluto- condition for cleaning. nium surface to large amounts

Site Return Processing 23 Advanced Cleaning Technologies (continued)

A major concern is the chemical in the first step, a high-pH to assess the effects of pH, compatibility of plutonium metal detergent solution is heated and temperature, detergent type, and with aqueous media. The corro- pumped over the part to remove time on the aqueous corrosion of sion of plutonium by water and organic residues from the sur- plutonium. Burnished samples dilute salt solutions is a rapid face. The cleaned component is of plutonium were weighed and reaction that produces hydrogen then rinsed with distilled water placed on the desired aqueous and a series of oxide hydrides or a selected buffer solution media for extended periods of and oxides.4 The possibility of before being vacuum dried time. Periodic visual inspections using aqueous cleaning media during the final step. were made, and mass changes arises because plutonium appar- Several advantages of the were measured after approxi- ently does not corrode if the pH process are recognized. The mately 2 weeks. is greater than 8.s system operates at low pressure, Results of the compatibility and the equipment requirements tests are consistent with earIier Concept and the safety concerns are less reports indicating that corrosion The concept of an aqueous than with carbon dioxide clean- is negligible in high-pH solu- cleaning process closely parallels ing. However, although the tions. Tests at 22°C show that that of the SCF carbon dioxide process is likely to generate only the metal remains untarnished sytem. Although the use of a low levels of waste, a processing after more than 24 hours in basic detergent solution in an facility will still be required to buffered solutions having pH ultrasonic bath is an attractive concentrate organic and deter- values of 7.0, 10.0, and 10.2 and option, the potential for corro- gent residues, to purify water, in high-pH commercial deter- sion from release of water vapor and to prepare fresh detergent gents. Tests with the same into the process faciIity is unac- solutions. solutions at 49°C show that the ceptable. Use of a closed-loop metal surface becomes only cleaning system is preferred. status IightIy tarnished during that The apparatus resembles that Initial experiments designed time period. Although distiIled shown for SCF carbon dioxide in to determine the feasibility of an water produced localized areas Fig. 1. After being placed in a aqueous cleaning process will of extensive reaction after 24 small-volume cleaning chamber, establish the chemical compat- hours, the surface was untar- a component is subjected to a ibility of plutonium with water nished after 1 hour at 220C. three-step cleaning procedure. and high-pH detergent solu- tions. Measurements are com- plete for a test matrix designed

24 Nudcar Materials Technology Division Annual Revkw “The success ofefforfs to define advanced cleaning methods hinges on the ability to determine the cleanliness levels attained by different procedures.”

These findings show that pluto- the cleaned surface is followed Cited References nium is compatible with warm by infrared analysis of the 1.K.M. Motyl,“CleaningMetal SubstratesUsingLiquid/SupercriticalFluid cleaning solutions and that solution. Although easily ac- CarbonDioxide;’RockwellInternational cleaned components can be complished, this technique is reportRFP-4150(January1988). rinsed with distilled water at based on the assumption that the 2.J. M.HaschkeandC E. C. Rense, room temperature. solvent is ideal and removes all “SupercriticalCarbonDioxideforCleaning Construction and installation residues. Reflectance and dif- Plutonium,”presentationat theNuclear MaterialsTechnologyDivisionReview, Los of a laboratory-scale system fuse-reflectance IWIR techniques AlamosNationalLaboratory(February1991). must be completed before are being investigated as pos- cleaning studies can be initiated. sible means for directly quantify- 3.J. M.HaschkeandS. J. Hale,“Altern- ativeSolventsforCleaningPlutonium: Cleaning efficacy will be evalu- ing hydrocarbon residues on ThermodynamicandKineticConsider- ated using infrared spectroscopic surfaces. ations,”LosAlamosNationalLaboratory methods, and optimal cleaning Development of a rinse reportLA-12255-MS(March1992). conditions will be defined. The method using Freon 113 solvent 4. J. M.Haschke,A. E. Hodges,III, G. E. decision to construct a pilot is complete. The technique Bixby,andR. L. Lucas,“TheReactionof facility is contingent on the analyzes for the total carbon PlutoniumwithWater:KineticandEquilib- riumBehaviorof Phasesin thePu+O+H results of studies of SCF carbon hydrogen concentration from all System,”RockwellInternationalreportRFP- dioxide cleaning. organic species by integrating 3416(February1983). the 2800- to 3000-cm-’ spectral 5. J. M. Haschke,“Hydrolysisof Analytical Procedures range and defines hydrocarbon Plutonium:ThePlutoniumOxygenPhase The success of efforts to levels as low as 0.3 ppm. With Diagram,”in Transuranium Elements: A Half Century (AmericanChemicalSociety, define advanced cleaning meth- samples from laboratory-scale Washington,DC,inpress1992). ods hinges on the ability to cleaning studies, the method can determine the cleanliness levels determine residue levels of 0.1 attained by different procedures. microgram of hydrocarbon per Fourier transform infrared square centimeter. The appara- (FTIR) spectroscopy is being tus and procedures for transfer- developed for indirect and direct ring rinse samples from the measurement of the organic glove box to the spectrometer are residue remaining on a surface demonstrated with nonnuclear after cleaning. Indirect measure- samples. Reflectance equipment ment follows a standard proce- for directly analyzing residues is dure in which a solvent rinse of now in design and fabrication. +

Site Return Processing 25 SITE-RETURN PROCESSING I Plasma Chemical Processing I by Joseph C. Martz Plutonium Metallurgy Group

Background Extension of plasma process- Plasma Fundamentals Over the past 20 years, ing techniques to plutonium Plasmas may be generated plasma processing has become production operations offers by a wide variety of excitation increasingly important in the many advantages. Plasma sources. Radio-frequency (rf) fabrication of microelectronic processing consists primarily of excitation is the most common devices. Since the late 1960s, gas/surface reactions conducted source, and plasmas created in semiconductor manufacturers at low pressure (1 to 1000 this manner are often called rf have exploited the characteristics millitorr). For this reason, by- glow discharges. Energy is of plasmas to create increasingly product formation is minimized coupled into the gas by ioniza- complex circuits. Application of (minimizing waste generation), tion of gas species, and transfer plasma processing to other feed chemical use is reduced, of energy is accomplished by manufacturing operations has remote operation is readily electron impact. Because elec- increased in recent years. Di- accommodated, and process trons are accelerated in the verse operations such as tool automation is easily imple- plasma by the presence of hardening, industrial and cos- mented. Specific application of electrical fields, they have con- metic coating, medical instru- plasma processing to plutonium siderable kinetic energy. Subse- ment sterilization, component production includes decontami- quent collision of these energetic cleaning, solar cell manufacture, nation of items exposed to electrons with other gas-phase analytical determination, and plutonium and other actinides, species results in substantial archaeological restoration have plasma-based cleaning of pluto- energy transfer. benefited from advanced plasma nium and nonplutonium compo- Examination of the collision processing techniques. Plasmas nents, selective removal of process reveals that electronic offer a unique chemical environ- plutonium compounds (such as states of atoms and molecules ment in which to deposit, alter, the selective etching of pluto- are selectively excited. If the and pattern a wide variety of nium dioxide from plutonium), collision is entirely elastic and materials. The plasma environ- and the growth of novel chemi- occurs without a change in ment offers an otherwise unat- cal layers on plutonium surfaces. internal energy of the species, tainable combination of reactive the electron will simply rebound chemical species and energetic from the massive neutral species particle bombardment, all at with little transfer of energy. room or near-room temperatures (300 to 600 K).

26 Nuclear MatwialsTcchnology Division Annual Reiiew “The plasma environment offers an otherwise unattainable combination of reactive chemical species and energetic particle bombardment, all at room or near-room temperatures (300 to 600 K).

Thus, elastic collisions are A more prevalent result of elec- Translational, vibrational, and incapable of imparting a signifi- tron impact is dissociation of rotational temperatures have cant translation energy to neutral molecular species caused by been measured at or near room species. Because the average excitation of electrons in bond- temperature in most plasma translation energy of a neutral ing orbitals to higher-energy systems. However, thermally species is a measure of its tem- antibonding orbitals, resulting equilibrated systems with tem- perature, electron impact results in species dissociation. In some peratures of several thousand in little or no temperature rise. diatomic plasmas, the degree kelvins would be required to Conversely, if the collision is of dissociation can reach 6070. achieve dissociation fractions inelastic and occurs with a In addition, most free-radical comparable with those of the change in internal energy, the recombination occurs as a plasma. Thus, the plasma is a efficiency of energy transfer three-body process, nearly nonequilibrium thermal environ- increases remarkably. A change all of which occurs heteroge- ment. in internal energy of an atom or neously at interfaces. Therefore, Though the concentration of molecule is equivalent to an free radicals have a long gas- is low compared with the excitation of the electronic states phase half-life, and most sur- concentration of neutrals, of that species. Thus, the effi- faces exposed to the plasma are charged species play an impor- cient transfer of energy to the subjected to a significant free- tant role in many reactions by neutral species from electron radical flux. breaking surface bonds, creating impact results in an excitation The free radicals resulting reaction sites, and enhancing of the electronic states of the from molecular dissociations product resorption. Ion bom- molecule or atom. define the unique chemical bardment provides a directional Electron-impact excitation environment of the plasma.They component to many plasma is sufficient to completely are often highly reactive species, reactions, allowing anisotropic remove one or more electrons such as free-radical halogens, pattern transfer. Heating effects from the outer electronic shells that provide a powerful chemical arising from ion bombardment of these species, thereby result- reagent in which to process a can play an important role in the ing in . The degree wide variety of materials. kinetics of many important of ionization in the plasma is chemical reactions. small, however—rarely occur- ring for more than 0.001‘%0 of all species in the plasma.

Site Relurn Processing 27 Plasma Chemical Processing (continued)

Fig. 1. Scheuuzficof reaction pathways within the carbon fetra/7uorideplasma. Circled species indicate stable reaction w+’ end products. Arrows indicate reaction of carbon-containing species. Note that most renctions produceatomic fi’uorine. I CF3+F ‘ e- M 4 +F e- \ 4 CO CFqe e- CnF2n+2 9 0 7 2 Despite the widespread use of < CF2+F o plasma processing in the manu- \ O fj 4P facture of solid-state devices, 5 +F many fundamental aspects of the v processes are poorly understood. 0 Simple two-component mixtures co ‘2F “- COF2 ent reactions.]~Optimization of 13 a the plasma environment often .- starts with enhancement of the ‘ co +2F active reactant concentration. \ Plasma parameters, such as 0 COF2 +(x-l)F CO +(x+1 )F pressure, applied plasma power, and system residence time, can & o have a dramatic effect on the production of desired atomic and molecular radicals. Figure 1 is a schematic of the The efficient generation of The classic example of important chemical reactions useful quantities of fluorine gas-phase optimization is the within the carbon tetrafluoride/ gives rise to a whole class of addition of to carbon oxygen discharge.4 Major prod- etching reactions based on the tetrafluoride discharges to ucts from these reactions include formation of volatile metal enhance fluorine production.3 carbon dioxide, carbon monox- . In principle, any For more than 20 years, ide, carbonyl fluoride, and large material that forms a volatile semiconductor manufacturers quantities of atomic and molecu- compound on reaction with have known that the addition lar fluorine. fluorine may be etched. Tung- of small amounts of oxygen sten, tantalum, niobium, carbon, (-10%) to carbon tetrafluoride germanium, titanium, molybde- can result in a significant in- num, boron, sulfur, uranium, crease in fluorine production. plutonium, and, of course, silicon are all candidates for fluorine-based plasma etching.

28 Nuclear Materials Technology Di\.isionAnnual Re$iew “In principle, any material that forms a volatile compound on reaction with fluorine may be etched.”

Other etching chemistries are If the ratio of carbon to fluorine Uxygen- and water-based possible. The most important in the feed gas is within a certain plasmas are often used as clean- of these is the chlorine-based critical range, only the polymeric ing agents. The strong oxidizing etching of aluminum and gal- film created by the discharge is potential of these discharges lium . Although alumi- etched. In such an equilibrium serves to ash nearly all organic num and gallium do not form condition, the net result is neither materials to carbon dioxide and volatile fluorides, they do form etching nor deposition. If this water. Materials traditionally volatile chlorides. Oxygen-based process occurs on an oxide resistant to solvent-based tech- etching of organic materials surface, the oxygen present in niques, such as radiolytically (plasma ashing) represents the surface helps to volatilize the cross-linked , are another important class of carbon-rich polymeric film, readily removed by these plas- etching reactions.5 yielding an excess of fluorine mas. This feature is particularly Plasma chemistry can be atoms. This excess fluorine is important in plutonium process- used to selectively etch certain available to etch the underlying ing because of the radiolytic materials in preference to others. substrate material. Thus, the reactions occurring at plutonium For example, numerous oxides oxide is etched, but the metal is surfaces. Plutonium parts (such as silicon dioxide) are not. This process yields selectivi- exposed to machining and other readily etched in perfluoro- ties as high as 200 to 1 for silicon oils (for longer than a few days) propane plasmas, whereas the dioxide-to-silicon etching. are usually difficult to clean. corresponding metals (such as Application of this technology Plasma cleaning offers the silicon) do not etch appreciably to the selective cleaning and benefit of cleaning these compo- in these environrnentsb’7 restoration of actinide surfaces nents while generating only (because of the tendency for appears promising. minimal quantities of additional carbon-rich discharges to form waste. polymeric films on surfaces).

Site Return Processing 29

— Plasma Chemical Processing (continued)

3 Fig. 2. Plutonium etch rate versus reactor pressure in carbon fefraffuoride/ 1 10% oxygen discharge. Power is 50 z ! wn~ts,system residence time is 10 + seconds, and temperature is 298 + keluins...... I ...... i 2 j A! : Plasma Decontamination j A j The potential advantage of A] 1 applying carbon tetrafluoride/ ...... ~...... ~...... :...... i...... ;...... oxygen plasma technology to 4 i i generate volatile plutonium 1 hexafluoride is clear. Efficient generation of fluorine by the : plasma, in addition to the en- o I I I i i hanced reaction rates available o 100 200 300 400 500 in the glow discharge, offers 600 significant potentiaI for actinide Pressure (mtorr) processing and decontamination. The application of plasma processing to plutonium volatil- Figure 3 compares the etch Plutonium dioxide has a high ization has been described rate of plutonium with that of surface area when prepared at elsewhere.8 Figure 2 shows the plutonium dioxide for several either room or elevated tenlpera- etch rate of plutonium versus samples processed at a pressure tures. Stakebake and DringmanQ reactor pressure in a carbon of 200 millitorr. The etch rate of report a surface area of 16.9 tetrafluoride/10’%oxygen plutonium dioxide is typically 5 square meters per gram and a discharge. Fluorine atom con- to 10 times higher than that crystallite size of 9.7 nanometers centration increases linearly with measured for plutonium metal. for low-temperature, unsintered reactor pressure across the range Several factors may account for plutonium dioxide, whereas the shown in Fig. 2. Thus, the etch the high etch rate of the oxide. sintered oxide is reported to rate appears to increase with have a surface area of 3.48 square increasing fluorine concentration meters per gram and a crystallite (possibly showing first-order size of 68.2 nanometers. A large kinetics). surface area provides a large etch area for the heterogeneous reaction of fluorine with pluto- nium dioxide, leading to en- hanced reaction rates.

30 Nuclear Materials Technology Ois,isionAnnual Rdcw 6 1 Fig. 3. Comparison of etch rates of plutonium and plutonium dioxide for i several etch runs. Pressure is 200 millitorr, power is 50 watts, and residence time is 10 seconds. 4

volatilization of plutonium hexafluoride proceeds consider- 2 ...... ably faster than the purely 4chemical reaction between fluorine and plutonium.12’*3 * , ,{ Several reasons exist for these differences in the etch rate. 0 Chemical sources of fluorine typically rely on surface disso- Pu PU02 ciation of a parent molecule and subsequent surface diffusion before reaction with plutonium can proceed. Conversely, the Further, it is possible that an Because of the high fluorine plasma produces fluorine in the oxyfluoride of plutonium may content of plutonium hexafluo- gas phase. A flux of fluorine exhibit a higher vapor pressure ride, the fluorine-to-carbon ratio atoms impinges on all surfaces than pure plutonium hexafluo- for plutonium dioxide etching exposed to the plasma, resulting ride, which would account for should be larger than that for in a high reaction probability the increased reaction rate for silicon dioxide; the equilibrium without the need for surface plutonium dioxide. This is fluorine-to-carbon ratio for diffusion. In addition, ion unlikely, however, as the vapor selectively etching plutonium bombardment plays an import- pressures of all known dioxide in preference to pluto- ant role in the plasma by creat- oxyfluorides of plutonium are nium should be nearer 4:1 (as for ing adsorption sites, promoting several orders of magnitude carbon tetrafluoride feed gas). reaction and surface activation, below the vapor pressure of This effect may also contribute to and enhancing plutonium highly volatile plutonium the observed increase in the etch hexafluoride resorption. All of hexafluoride, for which the rate for plutonium dioxide. these factors may contribute to vapor pressure is 43.35 The observed plasma etch the high etch rate for plutonium kilopascals at 52°C.*0’” rate of plutonium dioxide com- dioxide observed in the plasma A third possibility to account pares favorably with that re- (as compared with the etch rate for the increased oxide etch rate ported for purely chemical with chemical sources). involves the fluorocarbon film sources of fluorine; plasma model described previously.

SiteReturn Processing 31

— Plasma Chemical Processing (continued)

Fig. 4. Schematic ofplasnm decontamination renctor. Main reactor body is 2.25-i)l.-thick glnss. Radio-frequency power at up to 300 zuattsis inductively coupled into the plasma by external copper electrodes.

Automatic Variable Conductance

13.56 M1-iz Unloading Generator (from “Cold” side)

(from “Hot” side)

Fig. 4 is a schematic of a Demonstration of the ability that processing times of only plutonium decontamination to decontaminate “real-world” several seconds are likely to be reactor currently in operation at items is proceeding with this needed to remove and recover TA-55. Radiolytically contami- equipment, and initial results plutonium at typical levels of nated items are placed in the are expected in early spring contamination. Well-established reactor at one end and, after 1992. Plutonium contamination procedures are followed to decontamination, are removed typically consists of small par- readily recover and contain off- at the other end. This procedure ticulate of plutonium dioxide. gas from this operation. is used to avoid cross-contami- Further, the quantity of pluto- Plasma decontamination has nation of plutonium during the nium dioxide present on a an immediate application in the operation. The plasma reactor is contaminated item is often less flow sheet for the Complex 21 self-cleaning. Established oper- than a few nanograms. The Plutonium Processing Facility. ating conditions ensure that all measured etch rate of plutonium Plutonium must be removed interior surfaces of the reactor dioxide and the surface areas from enriched uranium compo- are exposed to the discharge. and particle sizes reported for nents before they are returned low-temperature oxidel’ indicate for reprocessing.

32 Nuclear Matmial$Technolcgy Divishm Annual ReVICW Cited References “Plasma decontamination of uranium in weapons 1. I. C. PlumbandK, R. Ryan,Plasm. Chem. Plasm. Proc. 6,205 (1986). disassembly should result in substantial waste elimination, 2. A.PicardandG. Turban,Plasm. Chem. a reduction in process times, and near elimination of Plasm. Proc. 5,333 (1985). radiation exposure.” 3. G. SmolinskyandD.L. Flamm,J. App/. Phys. 50,4982 (1979).

4. J. C. Martz,D.W. Hess,andW. E. Anderson,Plasm. Chem.Plasm.Proc. 10,261 (1990).

5. R. W. Kirk,inTechniques and Applica- tions of Plasma Chemistry, J. R. Hollahanand The acid-wash process currently Evidence exists that a uniform A.T. Bell,Eds.(Wiley-Interscience,New used generates many liters of plutonium dioxide film will York,1974),p. 347. mixed waste, requires several passivate the metal to further 6. J. W.CoburnandH.F. Winters,j. Vac. hours of manual scrubbing with oxidation. Previous work has Sci. Technol.16,391 (1979). an abrasive pad, and results in shown that dioxide plasmas can 7. J. W.CoburnandE. Kay,IBM J. Res. considerable personnel radiation grow uniform, adherent oxides Develop. 23,33 (1979). exposure. Plasma decontamina- on many metals. Therefore, it 8. J. C. Martz,D.W. Hess, tion of uranium in weapons may be possible to both clean J. M.Haschke,J. W.Ward,andB.F. Flamrn, disassembly should result in the plutonium surface and grow ). Nucl.Mater. 182,277 (1991). substantial waste elimination, a a well-characterized, uniform 9. J. L.StakebakeandM.R. Dnngman, reduction in process times, and oxide film that passivates the J. Nucl. Mater. 23,349 (1967). near elimination of radiation plutonium to further oxidation. exposure. The advantages of This process may be of benefit 10. J. M.Cleveland,inPhitotrium Handbook, 2ndcd.,O.J. Wick,Ed.(American plasma processing in this appli- for long-term storage of NuclearSociety,LaGrangePark,Illinois, cation are numerous. plutonium. 1985),p. 355. Other novel compounds such 11. B. Weinstock,E. E.Weaver,and Other Applications of Plasma as oxychlorides and oxyfluorides J. G. Maim,). hrorg.Nucl.Chem. 11,104 Processing have been produced by plasma (1959). The use of plasmas for final exposure. Uniform layers of 12. G. CampbellandB.A. Dye,Internal cleaning operations in weapons plutonium oxydifluoride and Communication,LosAlamosNational manufacture offers considerable plutonium oxydichloride are Laboratory(1988). promise. Oxygen-based plasmas of interest for use in numerous 13. J. G. Mahn,P. G. Eller,andL. B. could easily remove the machin- reaction studies. Previous work Asprey,J. Am.Chem.Soc.106,2726(1984). ing oils used during production at Los Alamos has shown that of weapon components. Further, tantalum surfaces exposed first the ability to remove even to carbon tetrafluoride dis- radiolytically polymerized oils charges and then to dioxide is a distinct advantage of the plasmas grow a uniform, adher- plasma. An added benefit of ent tantalum oxyfluoride film. oxygen-plasma-based final This technique may be extended cleaning is the potential to to plutonium. + modify the plutonium surface to a corrosion-resistant state.

Site Return Proces.shg 33 AD VANC E D MAN U FACTU RI N G TEC H N O LOGY Advanced Manufacturing Technology Overview by Mike Stevens P1utoniumMetallurgy Group

The manufacturing of pluto- and process development experi- At Los Alamos, we use a nium components for nuclear ence from the Rocky Flats Plant, custom-designed induction weapons has traditionally used a has Ied to a baseIine manufactur- casting process featuring sepa- wrought processing scheme ing scheme that addresses these rate coils for both an upper wherein plutonium is cast in a wider health, environmental, crucible and the lower mold. In form suitable for subsequent and capital-intensity issues. operation, a manually operated rolling and hydroforming to a The principal guiding phi- stopper rod and stirring paddle near-net shape. These shapes are losophy in this effort has been hold the melt in the crucible. then further processed by preci- to substitute modern near-net- When ready for casting, the sion machining to reliably shape casting for the traditional operator puIls the stopper and produce a part with tightly held wrought processing scheme. the metal pours onto a metal dimensional tolerances and a In near-net-shape casting, a runner tray that feeds the molten high degree of reproducibility. premeasured and alloyed charge metal into the mold gating This processing scheme was of molten plutonium is direct- system. We have traditionally chosen because of the wide gravity cast into a reusable metal used graphite molds in nested industrial familiarity with or graphite mold. This technique configuration with calcium wrought processing and some has been in use at both weapon difluorideas a mold coating to limited processing conveniences. design laboratories for the protect against reaction between At the time wrought process- fabrication of components for the plutonium and the graphite. ing of plutonium components Nevada Test Site experiments Current development work was implemented, capital and other development projects. focuses primarily on improving investment and maintenance, Additionally, the Rocky Flats the customized casting furnace radiation exposure to personnel, Plant used shape casting for by adapting a design begun and waste streams and residues several production projects for collaboratively between Rocky generated were not important which wrought processing was Flats Plant and Retech, Inc., a considerations. Recently, how- unsuitable. specialty furnace manufacturer. ever, a reexamination of the manufacturing scheme, using prototype production experience from Los Alamos and Lawrence Livermore national laboratories

34 Nuclear Materials Technology Oivision Annual Reticw “The principle guiding philosophy in this efiorf has been to substitute modern near-net-shape casfing for fhe traditional wrought processing scheme.”

During 1992 we will be installing Immediately following part To further reduce residues a new version of an induction- casting and heat treatment, the (that k, to prevent plutonium heated tilt-pour furnace that will part is moved directly to pre- oxide accumulation) and control allow us to conduct casting liminary inspection stations for fire hazards, we have also been experiments under high-vacuum visual, radiographic, density, investigating machine chip conditions. The new design will and dimensional examination management methods. The eliminate operator radiation and then to machining. There, essential idea is to collect the exposures by allowing for another subtle but very impor- machine chips in real time using remote operational control of the tant difference in technique is a vacuum-generating device, furnace during melting. employed. In the past, machin- such as a venturi tube, and then Ongoing experiments focus ing of plutonium parts included package the chips for rapid on development of a split mold flood cooling and lubrication of delivery to a pyrochemical design that will facilitate easy the part/tool interface with a processing station where they removal of the part and reuse of light oil. These processes neces- are molten processed under the mold. We have also begun sitate cleanup with organics calcium chloride with calcium development of special fixtures such as carbon tetrachloride, metal, resulting in a recovery for “creep” annealing of pluto- a suspected carcinogen, and of more than 99.9’70of the nium parts following casting. 1,1,1-trichloroethane, a chlorof- plutonium metal. This metal Such a process will allow the luorocarbon slated for elimina- is then directly returned for part to more closely assume the tion. The Los Alamos Plutonium foundry feed, with minimal necessary final dimensional Facility (TA-55) has long prac- residue stream generation. contours before machining. ticed “dry” machining of pluto- Another important aspect These and other details of our nium, which requires no organic of successful plutonium ma- casting development work are cutting aids or solvents. The chining is rapid turnaround covered in more detail in the lathes used to dry machine to the machinist of accurate article “Plutonium Casting and plutonium are enclosed in gauging information so that Forming.” well-engineered and isolated the control software can be inert glove boxes not only to corrected to compensate for pre- serve the metallic finish of tool wear, temperature instabili- freshly machined parts but also ties, and machine inaccuracies. to prevent combustion of the finely divided and pyrophoric plutonium turnings.

Advanced Manufactwing Teclmology 35 Advanced Manufacturing Technology Overview (continued)

Today, this information is gath- Joining technology used in In the past, the use of large ered by removing the part and later stages of nuclear primary electron-beam welding facilities gauging it at a separate station. fabrication has been based required special handling Plutonium metallurgy person- principally upon electron-beam procedures and the mainte- nel at Los Alamos have explored welding methods, the state-of- nance of associated vacuum the use of on-machine gauging, the-art technology when Rocky systems. Duplicate welders a technique in which a Flats began production, and its were required for plutonium noncontacting transducer application has been largely and nonplutonium applications, mounted to the tool post would successful. In recent years, and secondary joining and provide, without part removal, however, powerful, compact brazing apparatus was required gauging information of equiva- laser systems capable of deliver- to finish unit fabrication. The lent quality. Ultimately, with ing focused energy deposition laser welding facility at TA-55 the proper signal processing and suitable for welding or machin- will feature an enclosed room interfacing to the tool positioner, ing applications have matured containing three glove boxes in this technique may allow for to the point where obvious which all joining operations for real-time compensation and advantages are available. As a prototype fabrication can be control of the machining process, result, the Los Alamos l?luto- accomplished. These gloveboxes guaranteeing true part contours nium Facility has purchased a will require only inert gas envi- time after time. The details l-kW, pulsed Nd:YAG laser for ronments, as opposed to expen- behind successful dry machin- multipurpose joining applica- sive vacuum chambers, and a ing of plutonium are discussed tions in nuclear weapons single laser will service each box at greater length in the article research. through fiber-optic cables “Plutonium Dry Machining.” switched through a multiplexer station.

36 Nuclear Materials Technology Division Annual Rm.iew “For more than 40 years, as it manufactured prototype test components, Los Alamos has been continuously investigating manufacturing improvements.”

Previous development work Unfortunately, the preferred While helping to define a at Lawrence Livermore National fluids include Freon and baseline manufacturing scheme Laboratory has shown that this monobromobenzene, organics for the modern nuclear weapons class of laser couples well to slated to be discontinued for complex, we are developing plutonium and other materials of various reasons. In gas many of the new technologies interest and can accommodate pycnometry, helium gas is that will result in lower capital filler metal feed, consumable charged into a space with the equipment expenditures, re- shims, or autogenous joining plutonium and then evacuated duced radiation exposure to applications. Additionally, the into a calibrated volume. The personnel, smaller waste-stream tuning of such a laser can be displaced volume of the part is volumes, and actual elimination altered for special drilling and/ thus accurately measured, and of waste in some cases. Impor- or machining applications, this volume combined with the tantly, Los Alamos does this in perhaps further minimizing the weight reveals the density. a pilot-scale manufacturing number of work stations neces- Preliminary tests with small environment using weapons- sary for manufacturing. metal samples have been suc- grade plutonium, thereby Researchers at the Los cessful thus far. ensuring that many factors Alamos Plutonium Facility (TA- For more than 40 years, as it related to implementation and 55) have also been investigating manufactured prototype test utility are addressed in a suitable a new method for accurately components, Los Alamos has environment. + measuring the density of pluto- been continuously investigating nium components, termed gas manufacturing improvements. pycnometry. Traditionally, plutonium component density must be determined by immers- ing the part in a compatible fluid of known density and by then weighing it. By comparing the weight in air with the weight in the fluid, we can ascertain the density of the component.

Advanced Manufacturing Teclmology 37 AD VAN C E D MAN U FACTU RI N G TE C H N O LOGY Plutonium Casting and Forming

S. Dale Soderquist and Jesus D. Olivas Plutonium Metallurgy Group

Introduction To meet the challenge of envi- Efforts to die cast near-net-shape Plutonium fabrication ronmental, safety, and health hemishell parts contributed to processes incorporate a wide considerations, Los Alamos machine and mold complexity; variety of complex and precise scientists have been rethinking therefore, die casting never techniques. Most of these tech- plutonium casting procedures to reached production status at niques were established during develop techniques that simplify Rocky Flats. the 1950s and 1960s and now the wrought fabrication process A proposed new process, require upgrades to meet the characteristic of operations at the based on die-casting experience technology needs of the 1990s. Rocky Flats Plant. The wrought at Rocky Flats and gravity- Of particular concern are efforts process typically required casting experience at Los Alamos, to simplify processes and mini- multiple steps as follows: involves shaped gravity casting mize waste while maintaining and final forming during heat product quality. Current re- 1. Cast plate treatment with reusable metal search, design, and development 2. Heat treat molds and heat-treatment fix- activities in the areas of near-net- 3. Roll tures. The process comprises shape gravity casting and final 4. Shear circle only three steps: forming of plutonium seek to 5. Heat treat reduce by half or more personnel 6. Form shape 1. Near-net-shape gravity cast radiation exposure, generation of 7. Heat treat 2. Simultaneous homogenize plutonium scrap and secondary 8. Machine and creep form waste, production floor-space 3. Dry machine requirements, and environmen- The wrought-fabrication tal pollution. method at Rocky Flats was The creep-forming step tailored to produce flat parts for (step 2) will increase flexibility Background rolling, forming, and machining and reduce tolerance require- Casting is a necessary and processes developed decades ments of the initial shaped cast- versatile part of all plutonium ago. Although a die-casting ing. Such a casting process is fabrication schemes. The casting program was initiated about 10 simple and relatively free of methods of the future will meet years ago to improve efficiency problems; the casting equipment requirements for minimization and minimize waste, the result- requires only minimal nlainte- of waste as well as for efficiency ing die-casting machine was nance, and the simplified mold of plutonium use. complex, cumbersome, and design will improve mold life. difficult to maintain.

38 Nuclear Materials Technology DivMon Annual Review “The casting methods of thefuture will meet requirementsfor minimization of waste as well as for efficiency of plutonium use.”

Implications for environmen- 1. Development of a subscale Recent Results tal issues are also favorable, as plutonium casting and forming Casting, heat treating, and the near-net-shape process process using graphite molds and final forming of a subscale part requires less plutonium alloy fixtures. have been completed. Gravity- than does the wrought process. 2. Development of metal casting equipment similar to Therefore, it should generate less molds by saturable carburizing or that already proved in a produc- primary plutonium waste in the nitriding and by coating with tion environment was used. form of plutonium-bearing . The results of the subscale residues. Reuse of molds and 3. Finite-element modeling to work are: hardware will result in lower optimize casting parameters and quantities of secondary waste. mold and fixture design. 1. Calculations predicted Also, better casting-furnace 4. Conduct of casting experi- correctly that the decrease in design and improved glove-box ments using nonradioactive density during heat treatment atmospheres will significantly surrogate alloys to shorten would significantly change the decrease plutonium oxide development time. dimension of the plutonium formation. At Rocky Flats most 5. Process flow modeling of part. The calculated dimen- plutonium waste was generated casting and forming to quantify sional change values were used during recovery of plutonium predictions of total waste genera- to design the mold and the heat- metal from plutonium oxide, tion and to identify areas needing treatment fixtures. and the plutonium foundry was improvement; incorporation of the single largest generator of results into larger process models 2. A split-mold design al- plutonium oxide. for the Complex 21 Plutonium lowed easy removal of the cast Facility to follow. plutonium part, thereby increas- Approach 6. Full-scale plutonium casting ing mold life, decreasing dam- Los Alamos scientists are and forming to verify all work age of the part during break out, undertaking a number of techni- defined in 1 through 5 above. and reducing waste. cal activities in parallel to de- velop a process using graphite 3. Inspection on a coordinate- molds and fixtures now but measunng machine showed that integrating reusable metal molds the contour of the heat-treated and fixtures later. These activi- part closely follows the contour ties include of the heat-treatment fixture.

Advanced Manufacturing Technology 39 Plutonium Casting and Forming continued)

Fig.1. Expansion o} plutonium to con~onnto contour of heat-treatment

Radial Increaseat EquatorSignificant

ThicknessIncreaseat PoleSmall

Fig. 2. Simplified depiction of density expansion and creep fornling during henf treatment.


Load as cast part in homogenization fixture. (At this stage, part is still , ‘- adhered to casting mold core).

The split-mold design allows easy release of the plutonium HOMOGENIZATION FIXTURE ~ cast part from the outer case. Figure 1 shows how expansion during the phase change result- Apply heat. Part expansion :* .;{ begins. Part releases from ._ .-, ing from heat treatment causes mold core and settles into the part to move out radially homogenization fixture. and closely conform to the —. —— contour of the heat-treatment fixture. Figure 2 shows how the core of the plutonium casting mold is positioned in the heat- treatment fixture and how the pIutonium casting releases from Continue heating. Part the mold core during heat cunforms to homogenization fixture. (Density expansion treatment and settles into the and creep result in close- heat-treatment fixture. tolerance part).

40 Nuclear MaterialsTechnology Division Annual Review Fig. 3. Inspectiondata at various stages oj the subscale casting process. 2.145 Heat-Treatment FixNrO 1 2.140





2.115 1! 1 1 1 1 I [ t 1 1 1 1 I 1 I Pole Equator Position on Part

The creep of the plutonium part Summary By using bottom-pour and tilt- caused by gravitational force Los Alamos scientists are pour plutonium casting fur- contributes to this hot forming developing a production process naces, the process applies exist- process. In the future we wil lbe for near-net-shape gravity ing technology rather than testing a low-thermal-expansion casting, heat treatment, and developing major new equip- metal fixture. forrning of plutonium parts. ment, as would be required in a Figure 3 summarizes the Key elements in the process are die-casting process. + inspection data recorded at gravity casting to shape, split- various stages of the subscale mold design for easy part re- process. The contour of the lease, and use of phase change plutonium part after heat treat- and creep during heat treatment ment closely follows the contour (homogenization) to expand the of the heat-treatment fixture. plutonium part into a close- tolerance heat-treatment fixture.

Advanced Manufacturing Technology 41 AD VAN C E D MAN U FACTU RI NG — TEC H N OLOGY

Plutonium Dry Machining by Rueben L. Gutierrez Plutonium Metallurgy Group

Introduction However, in 1986, the Pluto- Combustion during dry The machining of plutonium nium Metallurgy Group, devel- machining of plutonium parts parts to exact specifications is oped a dry machining technique is prevented by performing the crucial in the development of that eliminates the need for operation in an inert glove-box nuclear weapon designs. Be- solvents and oils during glove- atmosphere in which the n~axi- cause plutonium metal is pyro- box operations involving ma- mum upper limit for oxygen is phoric and the cutting operation chining of plutonium metal. 3000 ppm. By using a low- performed during machining Implementation of the dry oxygen atmosphere, machine produces heat from friction, the machining process at Rocky Flats turnings do not undergo surface metal is susceptible to ignition would have significantly re- oxidation. and combustion when exposed duced the waste streams being to air during the process. Before generated during the production Machining Support Operations 1986, machining of plutonium operations for the manufacture Two other areas presently parts for weapons research and of nuclear weapons. Use of dry under development will enhance development at Los Alamos machining rather than flood the dry machining operation. required the use of freon for cooling with oil would have One is application of a vacuum cooling during machining. eliminated the need for 2,500 technique for collecting chips Also, the Rocky Flats process for gallons of cutting oil and 15,000 produced during machining, and machining production quantities gallons of trichloroethylene, the other is an in-process tech- of plutonium parts required that which is used as a cleaning nique for gauging the contours plutonium parts be flood cooled solvent, annually. of produced parts. with oil. The oil added to cool the part during production machining not only prevents combustion of the plutonium metal but also minimizes expansion of the part.

42 Nuclear Materials Technology DivMon Annual Review Plutonium Dry Machining (continued)

Before production operations An in-process method for Current and Future Develop- at Rocky Flats stopped, person- gauging machine performance ments nel there had initiated a tech- will provide precise gauging Although dry machining is nique for removing plutonium information of the part being ready for production operation, chips as the part was being machined. The technique in- a few enhancements are being machined. Called Vortex, the volves the use of a variable addressed. For instance, we are technique involves using a impedance transducer (VIT) to investigating thermal cooling of vacuum to suck the metal chips measure the machined surface the pot chucks, which hold the away and siphon them into a of the part. The VIT works in part, and the tool bit. The tech- canister. Before this method unison with the tool bit and the nology for vacuum collection was introduced, machinists lathe’s preprogrammed control- of machine chips is nearing pulled the chips away with a ler. Once this technique is fully completion. However, in- pair of tweezers and dropped developed and implemented, process gauging of machined them into a canister. The Vortex we will no longer need to re- parts is in the seminal stage of system minimizes radiation move parts from the lathe to development and will be ready exposure by allowing personnel confirm accuracy. This will for production operation in to withdraw from the glove box. minimize the number of times about 2 years. It is fully expected This technique is being refined a part must be handled, thereby that dry machining, chip collec- and will be incorporated into reducing the potential risks of tion and management, and in- the TA-55 plutonium machining damage to the part and of per- process gauging will be fully operations. sonnel radiation exposure. developed as a cohesive opera- tion within the next 2 to 4 years. +

Advanced Manufacturing Technology 43 NITRATE R E C O V E R Y ““ Nitrate Recovery Overview by Bill McKerley NuclearMaterialsProcessingGroup:NitrateSystems

The Plutonium Facility of the The nitrate recovery baseline A large quantity of bulk materi- Future, commonly referred to as flow sheet consists of the follow- als generated from other opera- “Complex 21,” will include the ing unit operations: tions will also require some disassembly of site-return pits, processing. The goal of the purification of site-return metal, ● Pyrolysis and Calcination nitrate recovery baseline flow assembly of product pits, recov- ● Pretreatment sheet is to recover the pluto- ery of plutonium from residues ● Acid Decontamination, nium, to produce a pure oxide generated in the production and Leachate Treatment for conversion to metal, and to recovery operations, and pro- ● Leaching ensure that the resulting resi- cessing and packaging of the ● Cascade Dissolution dues are in a form that meets all wastes for shipment and dis- ● Anion Exchange waste acceptance criteria. posal. This overview focuses ● Precipitation The pyrolysis and calcination on the nitrate recovery baseline ● Calcination operations will support several flow sheet, which is an integral ● Evaporation flowsheets. As currently envi- part of the overall baseline sioned, these operations will plutonium faciIity flow sheet At the Los Alamos Plutonium produce an ash from combus- outlined on page 9. The current Facility as well as Complex 21, tible materials for further chemi- nitrate recovery operations at the primary feed source will be cal recovery of the residual TA-55 provide the basis for plutonium process residues from plutonium. An incineration-type the nitrate recovery baseline the recovery, manufacturing, and capability is a critical step in the flow sheet envisioned for analytical laboratory operations. flowsheet but presently is @ Complex 21. considered to be a licensable/ permittable process. Conse- quently, we are investigating several alternatives, such as a unit that is performed in an inert atmo- sphere, molten-salt thermal decomposition, and supercritical water oxidation.

44 Nuclear M, NerialsTechnology Division Anntml Reki.w ‘The F%4torziwn Facility of the Fuh.-we,commonly rejerred to as ‘Complex 21, ’ will include the disassembly of site return pits, purification of site return metal, assembly of product pits, recovery of plutonium from residues generated in the production and recovery operations, and processing and packaging of the wastesfor shipment and disposal.”

Pretreatment operations The acid decontamination Process analytical chemistry include sorting, milling and and Ieachate treatment opera- developments will allow the real- grinding operations, that are tions chemically remove pluto- time determination of key pa- used to segregate and size- nium surface contamination rameters, such as acid concentra- reduce residues, as needed, from Oralloy parts. These parts tion, fluoride ion concentration, before dissolution. Also, we are leached with nitric acid to and plutonium concentration. are collaborating with research- remove residual plutonium This will allow better process ers in NMT-3 to develop and contamination. The clean, control, which directly affects the demonstrate (on a production nonplutonium metal will then ability to reduce waste, provides scale) magnetic separation be acceptable for return to the better materials control and techniques such as magnetic- uranium handling facility. accountability, and greatly roll or drum-type separators The solution (leachate) will be increases process efficiency. and high-gradient magnetic transferred to ion exchange or The nitrate solution is filtered, separation. This physical waste treatment for further and the undissolved solids are separation technique supports processing, depending on the collected and dried. The undis- waste minimization efforts by plutonium content. solved solids are either recycled allowing only plutonium-rich Nitrate leaching/dissolution or disposed of as waste, depend- residues to be sent for aqueous processes produce plutonium ing upon plutonium content. recovery. The plutonium-lean nitrate solution by dissolving Dissolution techniques such as portion is suitable for transfer and/or leaching plutonium the catalyzed electrochemical to waste management for dis- oxide from plutonium-contain- plutonium oxide dissolver are posal. Other physical processing ing materials using nitric acid being evaluated to determine methods may be necessary, and and fluoride ion. Dissolution their application on hard-to- we continue to investigate new takes place in dissolver pots or dissolve residues. The filtered approaches. cascade dissolution systems solution is stored in tanks and where the flow rate of feed and analyzed for subsequent process- reagents differs with the differ- ing in the anion exchange system. ent feed materials.

Nitrate Recovery 45 Nitrate Recovery Overview (continued)

The purpose of the anion If the plutonium content is above The addition of solid oxalic exchange process is to concen- the discard limit, the effluent is acid to a plutonium nitrate trate and purify plutonium in recycled. The nitric acid wash solution results in the formation nitrate solution. The nitrate cycle removes residual impuri- of an insoluble complex that solutions are first analyzed for ties from the columns. The wash precipitates from solution. This acid concentration, plutonium solution is also analyzed before solid plutonium oxalate complex valence, and plutonium concen- transfer to the acid recycle is colIected by filtration and is tration. The acid concentration system. transferred to the calcination is adjusted to 7 ~ by adding During the elution cycle the operation where excess nitric either concentrated or dilute plutonium is removed from the acid and water are removed nitric acid (HNO~)as required. ion exchange resin by the addi- and the plutonium oxalate is The Plutonium is stabilized in tion of a reducing agent such as converted to plutonium dioxide. the (IV) valence by the addition hydroxylamine nitrate or with The thermal decomposition of of reagents such as hydrogen the use of dilute nitric acid. the oxalate ion takes place at peroxide. In 7N_lnitric acid, The eluate, containing the puri- approximately 600°C or above. plutonium forms an anionic fied plutonium, is sent to the Enhanced precipitation complex that will adsorb on precipitation step. After elution, techniques such as homogeneous anion exchange resin. The anion the resin is returned to a nitrated oxalate and hydroxide precipita- exchange operation is essentially state by reconditioning the tions are being investigated. a four-step process— loading, coIumns with 7 ~ nitric acid. These precipitation techniques washing, eluting, and The ion exchange columns are hold the potential for easier reconditioning. now ready to repeat the entire filtration and lower actinide In the loading cycle, pluto- cycle. Current R&D activities in levels in the filtrates. nium is adsorbed on the anion resin development, process The product from this pro- exchange resin. The effluent analytical chemistry, process cess, the dry plutonium dioxide, from a load cycle contains the chemistry, and process control would then be transferred to the elemental impurities and is and instrumentation are yielding chloride recovery area for con- transferred to the acid recycle results that are directly appli- version to metal using multicycle system after being analyzed for cable to the needs of today’s direct oxide reduction (MCDOR). plutonium. plutonium recovery operations as well as the requirements for Complex 21.

46 NucIcar MatwialsTechnology Civis{on Annual Review “Tlzeseadvances in process control will not only allow an enhanced capability to manage our recovery operations, but will also support a superior materials control and accountability program.”

The nitric acid recycle portion The product from this process In many of the operations of the nitrate recovery baseline (pure, reusable 12 M HN03) will described above, there is a need flow sheet incorporates evapora- be used, as required, throughout for real time information regard- tion, oxalate ion destruction, the nitric acid recovery system. ing acid concentration, anion nitric acid fractionation, and The waste streams from this concentrations, plutonium nitrate destruction unit opera- process are CO, and N, off- valence, impurity concentra- tions. Solutions such as ion- gasses, evaporator bottoms tions, etc. By providing this exchange effluents and oxalate containing concentrated impuri- important information to the filtrates are transferred to an ties, and a dilute nitric acid process engineer in real time or evaporator in preparation for stream from the fractionator. near real time, decisions can be nitric acid recycle. This requires Reagent recycle is obviously made to tailor the processing several process steps: an important component of our parameters to the appropriate waste minimization efforts. conditions. In addition, this 1) oxidation of oxalic acid to We are currently demonstrating process information is being C02 and I+O; nitric acid recycle on the Ad- combined with a modern com- 2) recovery of HNO~from vanced Testing Line for Actinide puter-based process monitoring evaporator bottoms; Separations (ATLAS). This and control system that will 3) fractionation of recovered advanced line will be the site allow processes to be operated nitric acid to form a dilute where many of the development for reduced waste, decreased nitric acid waste stream and demonstration activities will personnel exposure, and purer and a concentrated and take place. product. purified nitric acid stream for recycle; 4) catalytic conversion of excess HNO~to benign Nzgas; and 5) disposal of the dilute acid evaporator bottoms to waste.

Nitrate Recovery 47 Nitrate Recovery Overview (continued)

These advances in process This overview of the nitrate control will not only allow an recovery baseline flow sheet has enhanced capability to manage summarized the unit operations our recovery operations, but will that will support Complex 21. aIso support a superior materials In addition, a brief glimpse has control and accountability been provided into the research program. These factors are vital development and demonstration for the plutonium facility of activities that are ongoing at today and are even more import- Los Alamos to ensure that the ant for the plutonium facility of plutonium facility of the future the future, which will most likely wilI have the capability to re- be required in a much more spond to a wide range of pro- restrictive environment. cessing requirements. +

43 Nuclear Materials Technology Division Annual Review NIT R AT E R E C O V ER Y Process Analytical Chemistry by Rick Day NuclearMaterialsProcessingGroup:NitrateSystems

The waste challenge for ● eliminate the need to repro- The following baseline tech- facilities in the DOE complex cess out-of-specification mate- nologies are now being demon- engaged in the aqueous recovery rial, strated on ATLAS: of plutonium from residues is ● identify process inefficien- largely a chemical processing cies, and . an ion chromatographyfor issue. In fact, one important way . better characterize and monitoring anion impurities, to minimize or eliminate waste is monitor waste stream composi- . an automated titration to address the problem at its tions. system for measuring free acid, source: in the process. The close ● a visible, near-infrared, fast- monitoring of process param- The Advanced Testing Line scanning spectrophotometer for eters and the early identification for Actinide Separations (AT- on-line measurements of pluto- of process upsets are key fea- LAS) provides the means for nium , nitrate tures of any system that seeks to testing, evaluating, and incorpo- concentration, and interfering minimize waste generation and rating into residue recovery anions, reduce cost, both in dollars and processing those process analyti- ● an on-line x-ray fluores- worker exposure. Laboratory cal chemistry technologies that cence spectrometer for impurity studies indicate that many of the have been proved in principle. metal analysis, and parameters that govern process ATLAS emphasizes the integra- . specific chemical sensors, operation can be measured tion of analytical methods into a including a chloride sensor and successfully using the on-line single system for supplying real- the R&D IOO-award-winning and at-line techniques of process time chemical information and high-acidity sensor developed by analytical chemistry. Processing applying that information to the Nuclear Materials Process— information thus acquired can processing refinements. The Nitrate Systems Group, NMT-2; formulation of developmental the Materials Technology Poly- ● lower reagent consumption, strategies for all processing mers and Coatings Group, MST- thereby reducing the amount of modules requires that analytical 7; and the Analytical Chemistry waste generated, methods be combined with Group, CLS-1. ● reveal levels of actinides in statistical process control and waste streams, thereby facilitat- experimental design. ing more efficient recovery operations based on real-time processing information,

Nitrate Recovery 49 Process Analytical Chemistry (continued)

Instrumentation of three Current on-line technologies Several compact chemistry- types is applied during the use advanced data analysis specific sensors are either al- development of process ana- techniques, including partial- ready in use or close to comple- lytical chemistry technologies: Ieast-squares analysis, funda- tion. The recently developed specially modified instrumenta- mental-parameter analysis, and high-acid sensor consists of a tion for at-Iine use in a glovebox commercially available instru- Hammond indicator bound in a environment, commercially mentation. A fast-scanning polymer coating and an optical available instrumentation for spectrometer multiplexed by flow cell monitored by the fiber- on-line use for real-time moni- fiber-optic cables to remote optic spectrophotorneter. A new toring, and chemistry-specific sampling locations performs chloride sensor applies a com- sensors developed at Los visible spectroscopy during mercial ion-selective electrode to Alamos for on-line use during anion exchange feed treatment, concentrations outside its nor- plutonium processing. column wash make-up, oxalate mal operating range; a similar At-line technologies such precipitation, and waste stream fluoride sensor is under develop- as the ion chromatographyand monitoring. Chemometric ment. An electrochemical sensor automated titration consist methods are used to analyze is being designed for use in of standard laboratory instru- spectral scans that measure total solutions containing mixtures of ments modified to work in a plutonium, plutonium oxidation uranium and plutonium. glove-box environment. At-line state, nitrate concentration, and The continuing development instruments in glove boxes are interfering anions. An x-ray and use of process analytical located adjacent to the process- fluorescence spectrometer not chemistry technologies and the ing Iocations and supply near- only operates at the line to resulting knowledge of process real-time information. The categorize various feed materials parameters and analytic ranges analysis they provide also but also monitors the ion ex- will remain evolutionary, as new serves as a “reference method” change effluent on-line to opti- methods and sensors continue to guide the development of mize wash volumes and track to be explored and evaluated. more advanced on-line and the actinide concentrations sensor methodologies. coming off the ion exchange column.

50 Nuclear MalcvialsTethnology Divkkm Annual Reticw “The waste challenge for facilities in the DOE complex engaged in the aqueous recovery of plutonium from residues is largely a chemical processing issue.”

An inductively coupled Process Analytical Chemistry Process Analytical Chemistry plasma mass spectrometer Applications to Complex 21. Benefits to Complex 21. being acquired to aid in the The instrumentation and Closer monitoring of process monitoring of waste streams methods being developed on parameters and early identifica- will also be used in near-line ATLAS are designed to supply tion of process upsets in Com- fashion to analyze solutions near real-time chemical analysis plex 21 will ensure that product before a concentration step on virtually all of the aqueous quality and waste minimization such as precipitation is per- unit operations found in the goals are met. Additional ben- formed. Detection of out-of- Complex 21 flow sheet for efits include better understand- specification material at this nitrate recovery of plutonium ing of the chemistry involved in point can substantially reduce scrap. The measurements being the processing, characterization waste by eliminating the need developed on ATLAS supply of process and waste streams, to rework out-of-specification information on important and minimizing the need to oxide. processing parameters including rework out-of-spec products. + Research in the area of sen- plutonium oxidation states, free- sors and related techniques, such acid concentration, interfering as flow injection analysis, will anions and trace metal impuri- continue. As industrial process ties. These process analytical analytical chemistry continues to techniques can also be applied grow as a field, the resulting to the Complex 21 flow sheets new instrumentation will be for chloride recovery and aque- evaluated for application to the ous waste streams, which share special requirements of actinide many of the same parameters process stream analysis within that need monitoring. the confines of the glove-box environment.

Nitrate Recovery 51 NITRATE R E C O V ER Y Process Measurement and Control by Noah G. Pope NuclearMaterialsProcessingGroup:NitrateSystems

.l?or many years, aqueous A strong control effort is By emphasizing process control processing at TA-55 and other required for administrative as well as automation, we rely nuclear materials facilities has reasons as well. At TA-55, these on the experience of the process been conducted with a hands-on, issues include the increase in operators and plant environment operator-based approach. Re- auditing requirements that has testing to constitute the founda- centIy, however, an effort to resuIted from new DOE orders tion on which automatic control incorporate modern industrial related to conduct of operations may be successfully instituted. In computer-based process monitor- and quality assurance. The anticipation of the requirements ing and control systems has been availability of computers along- of the Complex 21 control envi- initiated. Complex 21 plays a vital side the processes also allows ronment, we have instituted a role in this program. Most, if not technical reports to be compiled program that covers the majority all, of the processes planned for in a more convenient and timely of processes within the nitrate Complex 21 will require some manner. flowsheet. The effort began by form of computer-aided process It is vital that NMT Division applying industrial control control or automation. Clearly, maintain a viable industrial techniques to the nitrate evapo- a strong control and automation control and automation capabil- ration unit operation. Using the program is essential to accom- ity. Towards this end, we have experience gained there, the plish these technical challenges. selected proven reliable and program was recently expanded Modern control technologies commercially available technolo- to include other unit operations will strengthen Co~plex 21 by gies that are common through- common to both reducing operator radiation out other, more mainstream TA-55 and Complex 21. In exposures to levels as low as chemical process industries. addition to evaporation, the unit reasonably achievable, minimiz- At TA-55 these capabilities are operation control systems under ing the generation of waste by being introduced incrementally development include dissolu- optimizing operations, increasing to increase the overall safety, tion, ion exchange, feed prepa- the understanding of the chemi- reliability, and efficiency of the ration, acid recycle, eluate and cal processes by applying itera- operating environment. oxalate precipitation, and tive techniques of data acquisi- calcination. tion and modeling, and increas- ing overall safety by incorporat- ing computer-supervised systems of alarms and monitors.

52 Nuclear Materials Technology Oivkion Annual Review “By emphasizing process control as well as automation, we rely on the experience of the process operators and plant environment testing to constitute thefoundation on which automation control may be successfully instituted.”

From the experiences gained A multitasking environment that Software Selection. Commer- on these projects and on a funda- allows on-line, real-time access cial software should be used so mental understanding of current to such information would be that scientists, engineers, and control technologies, a number ideal. operators spend their time of important development configuring the system rather principles have been established. Hardware Selection and than writing custom software These principles and the projects Configuration. Hardware and drivers. Their expertise lies to which they have been applied should be decentralized to avoid in process operations, not in the are outlined as follows: reliability problems common to inner workings of a computer. large single-processor systems. Therefore, operators and line Information Flow. Informa- A network of several small supervisors should be able to tion should be shared between computers, which are consider- customize and modify their unit operations for the total ably less expensive and easier to process screens without in-depth operation to flow smoothly from replace than a single large knowledge of computer pro- start to finish. Thus, a common computer, provides several gramming. information data base should be layers of back-up processor accessible from a variety of power should power fluctua- Control System Concept. processors and software lan- tions, contamination, or other Because process operators guages. Because process param- facility problems cause a com- possess by far the greater control eters derived during one opera- puter to fail. Although small intelligence, the control system tion may be of value in a subse- computers lack the speed com- should serve as an extension of, quent process, such information mon to large systems, personal rather than a replacement for, should by readily available. computers with 80386- and their capabilities. Operators For example, during plutonium 80486-type processors have stabilize the environment by processing, the amount of oxalic proved to be fast enough to exerting an intelligence and acid added by a technician to handle most industrial process- flexibility that far exceed the complete the precipitation step ing situations. qualities of even the most ad- directly affects the performance vanced computers. Thus, the of the downstream waste evapo- control system’s function would rator, a system operated by be to increase the operators’ different technicians. ability to interact with a process.

Nibate Recovery 53 Process Measurement and Control (continued)

However, the control system Current Development Of the control projects in should be sufficiently flexible Projects. NMT-2 presently has progress, ATLAS has by far the to accommodate unforeseen under way several process most advanced capabilities. circumstances because most control and measurement Designed to encompass most processes have a finite life projects that embody the fea- of the unit operations on the expectancy, and modifications tures specified above: the Nitrate Recovery flow sheet for may be required to meet new enhanced evaporator process, Complex 21, ATLAS presents processing needs. The control the metal preparation line, the control challenges common to system should be layered so that Advanced Testing Line for large, multiple process plants. it has at least two back-up modes Actinide Separations (ATLAS), To meet these challenges, three of operation, one of which and the multipurpose cascade 80386- and 80486-based Compaq would be a manual override dissolvers. These projects use computers running the 0S/2 capability to ensure that all similar computer hardware and operating system are networked operations continue even with- software and similar input/ together to run a commercial out computer control. Preserva- output hardware. control software package. tion of the excellent manual The enhanced evaporator Each computer is located near a control operations at TA-55 is process, which is a technology different unit operation, and a essential because of their proven common to both TA-55 and network link to other areas of track record and their contribu- Complex 21, has more than two TA-55 allows system design and tion to the training effort. dozen inputs and has operated supemision to be performed successfully for more than 2 outside the laboratory. Each years. The system throughput is piece of input/output hardware nearly double that previously uses a commercially supplied achieved, and the number of software driver. A network operators required has been security system tracks man- reduced by half. The data- power usage and helps ensure Iogging capability has proved that only qualified personnel are valuable for the diagnosis of allowed access to the system. process upsets.

S4 Nuclear Materials Technology Divk[on Annual Rcvlew “Designed to encompass most of the unit operations on the Nitrate Recovery flow sheet for Complex 21, ATLAS presents control challenges common to large, multiple process plants.”

All ATLAS operators have NMT-2 has developed a clear been trained to create their own methodology for upgrading Los custom control screens. A Alamos’ process capabilities to complete, automatic data- include a process measurement logging capability allows large and control system of the type quantities of information to be described here. The transition collected for on-line or post- from computerized process process analysis. ATLAS in- control to automation of the cludes both batch and recipe process itself requires careful control capabilities, and an on- deliberation based on experience line statistical quality control gleaned from work with simpler package will be incorporated to systems. Future processing assist operators in process systems should be designed diagnostics. A complete super- with control system constraints visory process alarm system is in mind. The challenges pre- available. Development time has sented by Complex 21 demand been reduced to a minimum by that technical developments be the use of proven, commercially based on sound engineering and available technology. scientific experiences. NMT-2 has made the required invest- ment in the area of process control and automation as part of our continuing effort to meet the needs of the nuclear weap- ons complex. +

Nitrate Recovery 55 NITRATE R E C O V ER Y

Process Chemistry by Gordon D. Jarvinen NuclearMaterialsProcessingGroup:NitrateSystems

The innovative separations The ongoing RD&D work Many of the accomplishments chemistry needed for the DOE in the nitrate systems group described briefly here are the to accomplish its goals of (NMT-2) covers a broad range of result of collaborations with other cleanup of the nuclear weapons activities, from short-term groups in the Nuclear Materials complex and more efficient improvements in operating Technology Division, groups operations in Complex 21 guar- processes to Iong-term efforts to from other Laboratory divisions, antees that research, develop- obtain fundamental knowledge and employees of other DOE ment, and demonstration of separation processes and facilities, universities, and indus- (RD&D) activities in process metal coordination chemistry. trial firms. chemistry at Los Alamos will The improvements in operating remain essential. The next processes that can be imple- Sortiizg,Decotztailziizatiotz,ami generation of production facili- mented in the near future will be Dissolution. Several new tech- ties, regardless of type or loca- incorporated into the baseline nologies related to the first step tion, will integrate advances in flowsheet for Complex 21. The in the plutonium recove~ pro- separations technology with on- longer range RD&D efforts will cess are in various stages of line sensors and computer provide alternative processing development. control systems to increase methods that enhance the Com- safety, reduce personnel radia- plex 21 baseline. The following . Magnetic separation of tion exposure, minimize waste, paragraphs summarize recent certain finely divided pluto- and improve product quality progress by tracking the flow of nium-containing solids into a and yieId. Developments at the a plutonium-containing residue small fraction that is relatively Los Alamos Plutonium Facility through the nitrate recovery rich in plutonium and a large will to the prototype sys- operation, which includes the fraction that can be discarded as tems to be integrated into the following steps: low-level waste has been demon- reconfigured production com- strated on a process scale, using plex. Even now, the cleanup of a ● sorting, decontamination, a commercially available open- wide variety of actinide-contami- and dissolution, gradient device. After separa- nated wastes and sites within the ● feed pretreatment, tion, the plutonium-rich fraction DOE complex requires the Qmetal ion separations, can be dissolved and the pluto- ability to tailor separations “ product preparation, nium recovered by aqueous chemistry to address widely ● recycling of reagents, and processing methods. different conditions. ● waste treatment.

56 Nuclear Materials Tduwlogy Division Annual Review “Developmentsat theh AlamosPlutoniumFacilitym“ll leadto theprototypesystm to be integratedintothe reconfigzwedp~oductioncomplex.”

Results from preliminary tests Feed Pretreatment. Fluoride is Metal Ion Separations. using a high-gradient magnetic usually present in the nitric acid A number of investigations are separation system are very solutions from the dissolvers contributing to efforts to facili- encouraging. Advantages of the because is tate the separation of plutonium high-gradient system relative to added to increase the disso- and americium ions from aque- the open-gradient device include lution rate of plutonium oxide. ous solutions. the capability to separate smaller Presently, aluminum nitrate is particles and operate on added to complex the fluoride ● Reillex HPQ is a aqueous suspensions, to prevent interference with polyvinylpyridine-based anion . An electrolytic cell con- the subsequent ion exchange exchange polymer developed at structed in a plutonium glove- purification of the plutonium. Los Alamos in collaboration with box line now enables researchers An octaazacryptand synthesized Reilley Industries. For several in NMT-2 to examine the use of by INC-4 appears to bind fluo- years this polymer has been the silver(I) /silver(II) couple to ride very selectively and routinely used at TA-55 for the promote the dissolution of strongly, even in the presence ion exchange purification of plutonium oxide in nitric acid of a great excess of nitrate. plutonium in nitric acid solu- under relatively mild conditions. NMT-2 is testing the use of this tions. Recently, we found that ● Collaborators in the Isotope material to remove fluoride from resin in use for 3 years and and Structural Chemistry Group, the processing solutions and to beginning to lose effectiveness INC-4, have found that eliminate the need to add alumi- could be largely regenerated by siderophores and synthetic num nitrate, which adds to the treatment with 1 M sodium analogues of siderophores show volume and complexity of the hydroxide. The regenerated promise in the removal of ac- waste solutions. resin showed improved kinetics tinide contamination from soils of plutonium sorption relative and surfaces. The siderophore to new resin, and the improved enterobactin was found to be kinetics of the regenerated more effective than 0.1 M nitric material is being studied in the acid and a variety of other hope of improving the kinetics chelating agents in dissolving of new resin as well. an aged plutonium hydroxide polymer.

Nitrate Recovery 57 Process Chemistry (continued)

● Spectroscopic studies of ● The use of chelating poly- These promising initial results plutonium nitrate complexes in mers and extractants sorbed on indicate a need for further aqueous and organic solutions polymeric supports to remove examination of the use of such sorbed on ion exchange mem- plutonium and americium from contractorsto extract plutonium branes are providing more the ion exchange effluent and the and americium from waste and information on the plutonium oxalate filtrate solutions is being process streams. complexes involved in the ion investigated. Duolite C467 exchange process. Careful (made by Rohm & Haas) shows Product Prep-zratiom Our group analysis of the visible spectra of promise for reducing the amount has been responsible for two plutonium(~) in 1 to 13 M nitric of plutonium remaining in the important contributions in the acid indicates that three major oxalate filtrate to quite low area of product preparation. complexes or groups of com- levels. We are also studying plexes are present in various several novel extractants of . A recently completed concentrations of nitric acid. The actinides [tetradentate new-generation metal prepara- complex that exists at intermedi- bis(acylpyrazolones), tridentate tion line is now in operation. ate nitric acid concentrations has triphosphoryl and phosphoryl/ It produces plutonium metal not been previously studied, but N-oxide Iigands, and octadentate from plutonium oxide by two- the intensity of its absorption tetrahydroxamates] for applica- step hydrofluorination to pluto- spectrum correlates with the tion in process operations. nium tetrafluoride followed by distribution coefficient of reduction to metal using cal- plutonium on anion ex- ● We tested the liquid-liquid cium. The new design incorpo- change resin as a function of extraction capability of a mem- rates computer-controlled nitric acid concentration. Thus, brane contactor module sold equipment to minimize labor- this unstudied species may be by Hoechst-Celanese using intensive operations and subse- the complex most crucial to the tributylphosphate in an aromatic quent neutron exposure. We ion exchange sorption process. solvent to extract uranium are testing use of a stirred-bed Further studies include measure- from nitric acid. Under test fluorinator to reduce hydrogen ments of ultraviolet, visible, and conditions, the 25-centimeter fluoride consumption and nuclear magnetic resonance moduIe performed as the yield a free-flowing product. spectra images. equivalent of one to two-and-a- half theoretical stages.

58 Nuclear Materials Teclmdogy Dividon Annual Review “The ATLAS facility is being used to examine the recycling by evaporation ofa considerable portion of the nitric acid used in nitrate recovery operations.”

We examined a technique that The major advantage of the Recycling by evaporation will eliminates the corrosion prob- hydroxide precipitation is the significantly reduce the volume lems caused by iodine by using much lower concentration of of nitrate effluents that must be a carbon dioxide laser to initiate plutonium remaining in the treated by the Waste Treatment the plutonium tetrafluoride/ supematant solution. The Facility (TA-50). The Los calcium reaction. Helium tubes decomposition of formamide Alamos-developed high-acid in the furnace monitor the alpha- and urea homogeneously gener- sensor will allow rapid monitor- neutron reaction in plutonium ates hydroxide in the nitric acid ing of nitric acid concentration in tetrafluoride, thus improving solution. Unlike precipitations the distillate. process control. Presently, an using alkali or alkaline earth alternative method is under hydroxide solutions, formamide ● The recycling of hydrogen investigation for the recycling and urea decomposition gener- fluoride in metal preparation of unreacted hydrogen fluoride ates a readily filterable solid. line operations, described previ- in which sorption occurs in a Because the bench-scale studies ously under Product Prepanz- stirred bed of . have been quite promising, this tion, is also an important accom- Such a method would eliminate method will be compared with plishment in this area. the need for the large volume of oxalate precipitation in the aqueous potassium hydroxide course of operations on the Waste Treatment. Although solution now used to trap the Advanced Testing Line for waste treatment activities are excess hydrogen fluoride. Actinide Separations (ATLAS). described in another chapter, some nitrate recovery operations . Downstream waste treat- Recycling of Reagents. The are directly applicable to this ment operations will benefit recycling of reagents used in increasingly important concern. from an investigation of the plutonium processing will result homogeneous precipitation in reduced waste production. ● Some residues generated of plutonium hydroxide during processing operations as an alternative to precipitation are presently processed without of plutonium(III) oxalate after ● The ATLAS facility is being being considered “waste.” elution of plutonium from the used to examine the recycling by ion exchange column. evaporation of a considerable portion of the nitric acid used in nitrate recovery operations.

Nitrate Recovery 59 Process Chemistry (continued)

For example, cotton cloths used ● We are collaborating with The implications of process to clean glove boxes often be- Rockwell International in the chemistry studies and technol- come partially nitrated and can preliminary testing of a molten ogy innovations are enormous contain significant quantities of salt reactor for destroying rags, for the nuclear weapons corn- plutonium. At present, the paper, plastic, and other com- plex of the next century. The regulatory situation prohibits bustible materials contaminated contributions of the nitrate incineration. With the agree- with plutonium. A molten salt systems group at Los Alamos ment of state regulators, we are system based on calcium dichlo- will continue to play a major now testing a thermal decompo- ride/calcium difluoride or role in the development of sition operation to reduce the sodium chloride/potassium acceptable plutonium proces- inventory of nitrated rags and chloride is being considered sing capabilities. + generate a solid residue that can because both salt systems are be leached to recover plutonium wastes generated from the should the amount warrant the oxygen sparging of effort. electrorefining salts or from the multiple-cycle direct oxide reduction process. Substantial waste reductions, in addition to the voIume reductions resuIting from the destruction of the organics, could be achieved by multiple use of these salts. This “thermal treatment” method may prove acceptable where incineration is prohibited.

60 Nuclcar Materials Tmkolo~ Division Annual Review NITRATE R E C O V ER Y Systems Integration by Bill McKerley NuclearMaterialsProcessingGroup:NitrateSystems

Los Alamos efforts to These activities can be For example, the fluoride added develop and demonstrate conducted successfully only to facilitate the nitric acid disso- efficient and effective nuclear if researchers in several areas lution of oxide may result in materials processing and combine their efforts to resolve higher levels of plutonium in the recovery technologies applica- the complex issues involved in ion exchange effluence because ble throughout the DOE com- plutonium recovery operations. fluoride interferes with pluto- plex have already been proved Therefore, the Nuclear Materials nium. This conflict can be beyond the bench, or pilot, Processing Nitrate Systems resolved by integrating the scale. Research, development, Group, NMT-2, conducts an process elements through appro- and demonstration work at the innovative process engineering priate planning and by develop- Los Alamos Plutonium Facility program that brings together ing prototype integrated experi- at TA-55 centers around three specialists in process chemistry, mental facilities. The concept primary activities: process analytical chemistry, and integrating the various processes process control. in plutonium recovery opera- ● optimizing existing pro- The conduct of many opera- tions is successfully demon- cesses to minimize waste gen- tions within DOE’s nuclear strated in the Advanced Testing eration and operator exposure, weapons and nuclear power Line for Actinide Separations ● developing additional programs requires many differ- (ATLAS), a testing facility that treatment or polishing opera- ent processing steps, and process can process and recover a wide tions that will convert a large upsets in one operation can variety of actinide-bearing scrap. fraction of the total waste vol- adversely affect other operations. Such a broad capability is neces- ume to benign effluents that sary because each process in the can be discharged with reduced recovery operation produces its impact on the environment, and own unique plutonium-contami- ● evolving new technologies nated residue, such as metal that will result in significantly shavings, crucibles, oxides, lower total waste generation and pyrochemical salts, and ash. reduce operator exposure.

Nitrate Recovery 61 Systems Integration (continued)

ATLAS plays a dominant role The solid operating data in such DOE programs as com- provided by ATLAS experi- plex reconfiguration and radio- ments will accomplish primary isotope recycle and recovery. It goals in waste minimization incorporates such technologies and will support activities in as enhanced process control and the reconfiguration of the DOE on-line analytical chemistry to complex. Furthermore, ATLAS, optimize the plutonium recovery other equipment and instrumen- process and to minimize waste tation at the Plutonium Facility, produced at the source and and the integrated systems reduce waste treatment and approach at Los AIamos storage requirements. Waste is ensure the smooth transfer further reduced by coupling of information among Labora- such optimized processing with tory scientists and personnel improved processing methods at other DOE sites. + in dissolution, ion exchange, precipitation, waste polishing, and final treatment techniques. Once these technologies have been properly demonstrated on ATLAS, they can be easily integrated into the current processing facilities at Los Alamos, the Rocky Flats Plant, and Westinghouse Hanford.

62 Nuclear Materials Technology Division Annual R.xicw CHLORIDE RECOVERY Chloride Recovery Overview by Joel Williams NuclearMaterialsProcessingGroup:ChlorideSystems

Many of thepmcesses Current chloride recovery A method that shows great planned for the Complex 21 projects that support Complex 21 promise is the use of gas chro- Plutonium Processing Facility cover a broad range of activities. matography to analyze the are chloride-based unit opera- In the area of aqueous chloride organic stream. Private industry tions. These include americium processing, the most important has long used this technique extraction from the feed metal, process improvement is the safely and reliably for just such electrorefining of the impure alternative diluent work for applications. metal, dissolution in HC1media, solvent extraction. This work Other major projects currently aqueous chloride purification has been ongoing for approxi- under way that will impact the using solvent extraction and ion mately a year and replaces design of any new facility in- exchange, precipitation, calcina- tetrachloroethylene (TCE), an clude tion of the precipitate to oxide, environmentally objectionable 1. dissolution studies to and conversion of the oxide to chemical, with an acceptable quantify process efficien- metal through multiple cycle organic diluent for tributyl cies for a variety of direct oxide reduction. phosphate. This work uses matrices, These unit operations can be dodecane as the primary diluent 2. additional work on chlo- grouped into two major catego- with decanol as a phase modi- ride ion exchange, and ries: high-temperature, molten- fier. The most significant opera- 3. the application of sensors salt, pyrochemical processes and tional effect of this change has for process monitoring and the more conventional chloride- been the reversal of the light and control. based aqueous operations. A heavy phases from the replace- For some of this work, we are brief review of chloride recov- ment of the TCE. As a result, collaborating with the process ery operations, as envisioned extensive cold testing has been development section of the for the Complex 21 Plutonium required to confirm the perform- Nuclear Materials Processing— Processing Facility, includes all ance of the centrifugal contractors Nitrate Systems Group. This of the aforementioned processes with the new diluent system. approach has allowed our except americium extraction The use of an alternative aqueous chloride operations to and electrorefining. For pur- diluent has created the need for use research being done to poses of process grouping, a more sophisticated technique support ATLAS in the nitrate these two unit operations are for evaluating the composition area. included in the site-return of the organic phase. processing discussion.

Chloride Recovesy 63 Chloride Recovery Overview (continued)

Future plans for the aqueous The sole pyrochemical Once demonstrated, this same chloride operations include the process included in the chlo- diagnostic technique can be replacement of virtually an ride recovery portion of the implemented in any process that entire glove box line. The experi- Complex 21 flow sheet is the uses chIorine as a reagent or that mental chloride extraction line multiple cycle direct oxide may generate chlorine as a by- (EXCEL) project calls for the reduction (MCDOR) operation. product. Because the technique removal of the existing solvent This process for converting oxide is noninvasive, we need only a extraction glove boxes and their from aqueous operations to simple modification of the off- replacement with chloride- metal has undergone several gas piping to implement the compatible, plastic-Iined boxes significant changes during the technology. as the start of this upgrade. past few years. The introduction Optimization of the MCDOR Another part of our long- of chIorine sparging to convert process is under way to reduce range plan is to incorporate on- the reaction by-product, calcium overall cycle time, further n~ini- line analytical techniques and oxide, to the calcium chloride mize waste generation, and specialized process diagnostics. process salt has resulted in improve the purity of the metal Because of special materials dramatic reductions in waste. product. The off-gas monitoring requirements in a chloride In addition, the use of chlorine in system has already been dis- environment, the development high-temperature operations has cussed as one of the optimization of wet chemistry techniques and opened the door to new tech- efforts. Automation of feed other noninvasive methods such nologies such as in situ genera- preparation, handling, and as sensors and spectrophotomet- tion of the plutonium trichloride introduction into the reaction ric measurements must be necessary in americium cell is under current develop- modified and adapted to the extraction. ment. The aim of this effort is glove boxes that will use the new This technology improvement to improve MCDOR through technologies. These new diag- has also required the develop- increased product consistency nostic and process-monitoring ment of more sophisticated off- and decreased personnel radia- capabilities will be incorporated gas monitoring capabilities. The tion exposure. Additional into unit operations as they are use of a newly installed spectro- automation will configure and demonstrated and will become a photometric technique for operate cells and remove and part of the design of any new detecting chlorine will become produce the final products. Complex 21 facility. an important tool for optimizing the regeneration step of the MCDOR process.

64 NucIear Materials Tcchnolugy Division Amual Revkw “The implementation ofa universal salt system for all pyrochemical operations has long been a goal of our process development.”

After the completion of a set The implementation of a operations, such as oxygen of reductions, the chlorination universal salt system for all sparging of electrorefining salts, of the to calcium pyrochemical operations has have also resulted in changes in chloride results in a salt excess. long been a goal of our process the composition of the feed to This salt, however, is free of the development. Calcium chloride recovery. Although all of the impurities found in commer- has been implemented as the individual unit operations have cially available calcium chloride salt-of-choice in americium been fully demonstrated, no and could be used to produce extraction and is currently being evaluation has been made of the product metal with the same demonstrated in electrorefining. overall, integrated flow sheet chemical composition as the Potential advantages of a univer- performance. Not only will such feed oxide. An initial set of sal salt include consolidation of a demonstration confirm the experiments to determine some pyrochemical unit opera- high level of confidence for product metal purity produced tions, simplification of the success, but also the use of the mixed results. Most of the metal aqueous recovery flow sheet, exact feed stream specified for showed no increase in impurity and reduction in the volume Complex 21 will demonstrate the levels compared with the feed of aqueous solutions processed direct applicability of the entire oxide. Some runs, however, because calcium chloride is flow sheet for the future facility. showed elevated levels of impu- significantly more soluble in The purpose of this program rities that were not in the feed HCI media than the sodium is the demonstration of each material. In the future, careful chloride/potassium chloride sequential process step: evaluation of product purity salts historically used in ameri- 1. americium extraction of the requirements will be necessary cium extraction and site-return feed metal, to produce a product with the electrorefining. 2. electrorefining, same chemical composition as A program is being devel- 3. recovering all chloride- the feed oxide. oped to demonstrate an inte- based residues, and grated chloride processing 4. converting the recovered scheme. However, production- product oxide to metal in scale aqueous chloride process- MCDOR. ing is relatively new; and changes in the pyrochemical

Chloride Recovery 65 Chloride Recovery Overview (continued)

I The goals of this work include Issues not fully evaluated in In conjunction with processing, the evaluation of process effi- the existing flow sheet include materials control and accountabil- ciencies on a known feed, the the requirements for analytical ity (MC&A) requirements must demonstration of an integrated or nondestructive assay equip- be carefully evaluated before flow sheet for residue recovery, ment, materials surge-capacity finalizing any process flow she&. and the conversion of oxide to requirements, critical process As part of MC&A requirements, metaI based on the pyrochemical equipment redundancy require- we will need surge capacity and processing of that feed. This ments, and the effect of differing assurance of safeguards for such demonstration will identify reliability, availability, and excess material storage. problems and provide an oppor- maintainability (RAM) character- The integrated demonstration tunity for process improvement. istics of the specific operations. of the chloride flow sheet will Overall waste generation One of the significant problems provide information and insight rates will be determined from a with Building 371 at Rocky Flats into these areas and help identify specified throughput of typical was the incompatibility of some potentially significant problems. + I site-return feed. This will give process unit operations. This more accurate information to building could not perform at its help specify waste stream con- design capacity because unit tent and quantities. Such infor- operations with different RAM mation will be invaluable in histories were implemented in sizing waste-handling require- lock-step fashion. ments and may identify poten- tial problems with specific waste constituents. By taking this approach, the program wilI exactly duplicate the waste- stream characteristics expected from the Complex 21 flow sheet.

66 Nuclear Materials Technology Divklon Annu.d Review c H LO R I D E RECOVERY In Situ Chlorination of Plutonium Metal by Eduardo Garcia NuclearMaterialsProcessingGroup:ChlorideSystems

Introduction Furthermore, the reaction be- Unfortunately, although the Plutonium trichloride is used tween chlorine and plutonium chlorination reaction is very as a reagent in the molten salt metal is expected to be much highly thermodynamically extraction (MSE) and more efficient than the reaction favored, the reaction is so exo- electrorefining (ER) processes. between phosgene and pluto- thermic that there must be Presently, plutonium trichloride nium dioxide, thus smaller careful control of chlorine flow is made by combining pluto- amounts of gas are needed to rates in order to prevent un- nium oxide and highly toxic generate equivalent amounts of wanted temperature excursions. phosgene. Because of this plutonium trichloride. Prelimi- In the direct chlorination of toxicity, an alternative synthetic nary work shows the feasibility plutonium metal for purification route to plutonium trichloride is of in situ chlorination for produc- purposes, the reaction tempera- highly desirable. By making ing the required plutonium ture can be maintained at accept- plutonium trichloride during the trichloride. able levels by proper flow processes in which it is used, control of the chlorine.* with less toxic reagents, we can Approach Another concern that gain in overall safety, decrease In the conventional MSE chlorination of plutonium waste generation, reduce radia- process, quantities of calcium metal introduces, and a concern tion exposure, and reduce the chloride, plutonium trichloride, of pyrochemistry in general, is number of accountability steps. and plutonium metal are loaded that of materials compatibility. A simple way to accomplish into a crucible. In situ chlorina- Chlorine gas is a highly corro- this goal is by direct reaction of tion generation, however, elimi- sive oxidizing agent, but molten elemental plutonium and chlo- nates the need to add plutonium plutonium metal is a highly rine. Alhough chlorine is a toxic trichloride at the beginning of a corrosive reducing agent. material, it is an order of magni- run and will be accomplished by tude less toxic than phosgene. sparging chlorine gas through the molten plutonium. Concep- tually, the chemical reaction is ve~ straightforward and simple:

2 Pu + 3 cl —> 2 ruc~. *T.R.Jarosch,J. B.Scaade,andS.D.Fink, SavannahRiverLaboratory,unpublished researchconductedatLosAlamosNational Laboratory,1991.

Chloride Rerovery 67 In Sitn Chlorination of Plutonium Metal (continued)

This kind of environment pre- tantalum crucible never comes in Another advantage is that no sents materials compatibility contact with chlorine gas. additional glove boxes and space problems because materials There are two possible meth- for separate MSE oxidant synthe- that can withstand highly ods by which contact between sis would be required. Because oxidizing conditions are usually chlorine and plutonium can be very little, if any, chlorine will chemically incompatible with maximized. One of these wouId escape from the furnace during highly reducing conditions and involve redesign of the crucible in situ generation of plutonium vice-versa. to increase contact time between trichloride in MSE, gas scrubber There are two possible the two reagents and minimize waste that is normally generated solutions to this problem. The the amount of unreacted chlo- from these processes will be first is to use magnesia crucibles rine escaping from the melt. The minimized to a large extent. because they have demonstrated second method uses stirring This process will not increase the minimal chemical attack in while sparging, which maintains personnel radiation exposure plutonium pyrochemical pro- intimate contact between the gas normally received from the MSE cesses and are, of course, inert to and the metal throughout the process but will, of course, chlorination. A magnesia cru- melt, thus optimizing the reac- eliminate the exposure received cible has the disadvantage of not tion. from a separate plutonium being reusable because it must Znsitu production of pluto- trichloride synthesis procedure. be broken in order to recover the nium trichloride for MSE would MSE is the logical process for product. have several benefits. It would investigating in situ chlorination The second solution is to use reduce accountability steps because of the simplicity of the tantalum crucibles, which are currently required for separate process. Electrorefining is currently used in MSE, because plutonium trichloride produc- another process that would they are reusable. Tantalum, or tion. Although chlorine is a toxic benefit from in situ generation of any other metal, would seem material, it is much less toxic plutonium trichloride, but the inappropriate as container than the phosgene currently increased number and con~plex- material because it is attacked used, and the reaction with the ity of the mechanical compo- readily by chlorine at elevated metal is predicted to be much nents render this process less temperatures. However, it may more efficient, reducing both the suitable. After in situ generation be possible to have a complete time required to effect the reac- has been perfected for MSE, the reaction between the chlorine tion and the amount used. knowlege and experience gained and plutonium metal so that the will be applied to ER. +

68 Nuclear Materials Technology Division Annual Ret+?w CHLORIDE RECOVERY Opportunities for Magnetic Separation Applications in Complex 21

Larry R. Avens, Laura A. Worl, and Karen J. deAguero NuclearMaterialsProcessingGroup: ChlorideSystems NuclearMaterialsTechnologyDivision F. Coyne Prenger, Walter F. Stewart, and Dallas D. Hill AdvancedEngineeringTechnologyGroup, MechanicalandElectronicEngineeringDivision TabZe1. Magneticsusceptibility of selected compounds and elements. The Magnetic Separation Process Compound/Element Susceptibility,10+ Magnetic separation is a physi- I?aramagnetic cal separation process that segre- FeO ...... +7200 gates materials on the basis of FezO~...... +3586 magnetic susceptibility. Because CrZOa...... +1960 the process relies on physical —. .GULL.- .-.-...... ,.,,,...... ,=...... +2370 properties, separations can be “*-P~- ...... ;.,..-...t...... :...... :.:...:::::...... - +1760 achieved while producing a *’. rn.A...... p...... :.:.:...... !t...... ,.....+1000 minimum of secondary waste. .-— 1GO:.:..;::...-..::.;...... ,..:...:..., ...... +730 .—.— .— — .- When a paramagnetic particle N~::...... +66U IIE+L!. encounters a nonuniform magnetic +“ ‘U ....:...... :...... +610 -.“ .-..” ..’” ,- . .. - field, the particle is urged in the . ..,.::..Jf f**...-.....,...... +409 ——.. --- direction in which the field gradi- @~~":::~""".>:"::.:;":"""""""""""""""""::"""""`"".:":.'""’173 ent increases. Diamagnetic par- ‘h...... +134 .-.— ticles react in the opposite sense. ELEO:.::...... :.:...... :...... :.:...... :...... +40 When the field gradient is of Ca ...... +40 sufficiently high intensity, para- Al ...... +16 magnetic particles can be physi- Diamagnetic cally captured and separated from Si ...... 4 extraneous material. Graphite ...... -6 Because all actinide compounds MgO...... lO are paramagnetic (Table 1), mag- CaO...... l5 netic separation of actinide-con- Th02...... -16 taining mixtures is feasible. Mag- MgF2...... ,...... netic separation on recycle pluto- CaF2...... -28 nium chemical process residues Si02...... -30 has been demonstrated on an NaCl ...... 3O open-gradient magnetic separator. A1203...... -37 The advent of reliable supercon- K Cl ...... -39 ducting magnets makes magnetic CaC~...... -54 separation of weakly paramagnetic Calz...... -109 species attractive.

Chloride Recovery 69 Opportunities for Magnetic Separation Applications in Complex 21 (continued)

Fig. 2. Dingrmnojn roll-or drum-type Feed Hopper )nagrreficseparator. 1’,,. ..!.~ $.,..:.:..-,.:;,,. .,,:.,.:/.- FeedTray Magnetic Separation Methods () Although numerous magnetic ~;;’1:. separation methods exist, the two we have selected for our ~-~:.:::,:::t Ma~ work are the magnetic-roll, or ,_Drum ,]: drum-type separator, and the ...’+, . . -- >-’1;_..,$, high-gradient magnetic separa- ..-.. . F,_.-< ,, / tor (HGMS). The usefulness of Thin Stainless ...... A ‘;::? Snlitter Steel Belt .... the open-gradient separator used ..-... ‘:, in the early work is limited by its low processing rate. A diagram of a roll separator is shown in Fig. 2. In practice, a ““’’’ty+ powder is delivered onto a thin belt that moves over rollers. The front roller is fabricated from a The roll separator we are The HGMS method is used to permanent magnet. Ferromag- cunently using contains the separate magnetic fractions from netic and sufficiently paramag- latest in permanent magnet gases or liquids. A diagram of netic particles are attracted to the technology: a neodymium-iron- the method is shown in Fig. 3. magnet and adhere to the belt in boron rare-earth magnet. The Most commonly, the feed is the region of the magnet. As the roll is constructed of rare-earth slurried with water and passed belt moves away from the magnetic disks separated by through a magnetized volume. magnet, the ferromagnetic and ferromagnetic spacers. This Field gradients are produced in paramagnetic particIes disen- generates high fieId gradients the magnetized volume by a gage from the belt and are on the surface of the roll. The ferromagnetic matrix material. collected in a catch pan. Diamag- roll separator has been installed The matrix can be steel wool, netic and nonmagnetic particles in a glove box for a demonstra- steel balls, foam, etc. pass over the magnetic roller tion with actual residues. relatively unaffected and are collected in a different catch pan. The operation results in a sepa- ration.

70 Nuclear Matericd.sTethnology Division Annual Review Feed Fig. 3. Simplified HGMS Diagram. Suspension Water An :“a”.~?+i;a <,:N. .,:-..:: ..-9/”\ >--- !<; ,=.,.,:,. /.Z., .>. ,- .., L -,.*: >- -, >.. :.:< .:/. Pv%.

Magnetic Separation Applica- tions in Complex 21 Several applications of Flux magnetic separation will be Return examined for Complex 21: Shell Stainless 1. concentration of recycled- Matrix Steel Wool plutonium, chemical Canister processing residues, 2. extraction of actinides from liquid wastes, and 3. development of reusable magnetic gas filters. We have shown that chemical process residues, such as reduc- tion slags, crucibles, graphite, and silica, can be segregated into Ferromagnetic and paramag- Higher fields offer the possibil- a plutonium-rich and a pluto- netic particles are extracted from ity of a broader range of HGMS nium-lean fraction. The pluto- the slurry while the diamagnetic applications than is afforded by nium content of the lean fraction fraction passes through the conventional electromagnets, from these demonstration magnetized volume unaffected. which are limited by the satura- experiments is sufficiently low The magnetic fraction is flushed tion of iron. in plutonium that it is from the matrix later when the For our HGMS work at Los uneconomical to recover the magnetic field is reduced to zero Alamos, we have a laboratory- plutonium value. Therefore, the or the matrix is removed from scale l-inch-bore, cross-field, plutonium lean fraction can be the magnetized volume. conventional magnet and a discarded directly in grout. Much higher electromagnetic larger, warm-bore supercon- Processing of dry residues is fields are routinely available ducting magnet. important not only for Complex- with today’s superconducting 21 processing but also for vol- magnet technology. ume reduction of the current DOE backlog.

Chloride Recovery 71 Opportunities for Magnetic Separation Applications in Complex 21 (continued)

HGMS might also be useful as Benefits of Magnetic Separation Magnetic filtration of fluid a selective filter for fluid waste in Complex 21 waste may be a method to cut generated during actinide The benefits of interjecting transuranic (TRU) effluents from chemical processing. Our mag- magnetic separation as a head- DOE facilities to near zero. This netic separation model predicts end unit operation include the would greatly reduce waste that HGMS can reduce the generation of only a very small treatment cost. actinide concentration in liquid volume of secondary waste. The Magnetic gas filters on glove waste streams by several orders ability to concentrate the actin- box process exhaust would also of magnitude. ides from extraneous materials An identified need in ura- before processing begins yie~-1 nium and plutonium operations more efficient recovery~ ra--’ =G:%;i.hi:i is the reusable filter for glove tion. This is true be u~e r must be chan ed. A r~usable box and hood exhaust. A reus- (acid) use is redu ? isso t“ w filter based & ‘“ able high-efficiency magnetic of more conce~?ate~geeds ne appea=e=$~?~- filter for paramagnetic particu- yields more centrated sol - A ,.- - ‘-B -.-. ‘i late appears feasible, but only a tions to ion chan e or solvent ‘.’ ‘‘- ~ F & small amount of work has been extraction nit oper%%_=—- ‘“” # conducted in this area. Because 1 s extr ous-rnateriaP–= & is leache an \ ;::::~c$~::~;!’+ ‘ ‘“


72 Nuclear Materials Tcchnolwg Division Annual Review “Acooperativeresearchand developmentagreementwas recentlysignedwithAWC/Lockheedtoexamineparamagnetic separationfor soildecontamination.”

Project Status The conventional HGMS unit The superconducting HGMS Cold testing of the roll separa- at Los Alamos is currently being is due in Los Alamos very soon. tor has been completed and it used in cold testing. Through After cold testing and model has been installed in a glove box. the use of development, one of the HGMS Soon, process demonstration will 1. various nonradioactive separators will be relocated for begin. The roll separator repre- surrogate materials with plutonium residue processing sents a pilot-scale demonstration different magnetic tests. for this technology. Data ob- susceptibilities, There are other important tained from this unit can be used, 2. different surrogate particle aspects of magnetic separation to design and fabricate a full- sizes, work at Los Alamos that do not scale processing unit with virtu- 3. parameter variation such strictly involve Complex 21. ally any number of separation as flow rate, solids loading A cooperative research and stages and processing rates. in the slurry, fluid viscos- development agreement was ity, etc. recently signed with AWC/ 4. magnetic matrix param- Lockheed to examine paramag- eters, and netic separation for soil decon- 5. magnetic field strength, tamination. In addition, a soil a performance-based HGMS decontamination study with model is being developed. Rocky Flats is anticipated. The hope is that given a separa- Use of HGMS to segregate tion problem, we will have the underground storage-tank ability to select the processing waste, a problem at the criteria that will achieve a Hanford site, is also being necessary per-formance level. studied. + Currently, numerous experi- ments must be conducted to determine optimum performance.

Chloride Recovery 73 CHLORIDE RECOVERY Oxygen Sparging by Eduardo Garcia NuclearMaterialsProcessingGroup:ChlorideSystems

Introduction Although this earlier effort had concentrated on actinide separation Before the advent of oxygen and not specifically on plutonium recovery, it was still a good sparge as a recovery process, foundation on which to build. calcium salt was used to strip Air sparging of salts was replaced by oxygen sparging in which plutonium from salt residues. a controlled mixture of oxygen and argon was used to provide In the resulting sodium chlo- improved process control. As new information was gained, process ride/potassium chloride salts, parameters were continually changed in order to improve perfor- excess calcium produced metal- mance. Oxygen sparging has now almost completely replaced lic and potentially pyrophoric calcium salt stripping as the method of choice for treating alkali metals. These waste salts, electrorefining salt residues. though below the economic discard limit, did not meet Approach Waste Isolation Pilot Plant Oxygen sparging has been used to treat salt residues, mainly (WIPP) criteria because of their from electrorefining, on the kilogram scale. Sodium chloride/ potentially pyrophoric nature. potassium chloride or calcium chloride salts derived from this To make these molten waste process contain plutonium in the form of dissolved plutonium salts acceptable to WIPP, work trichloride as well as some uncoalesced metal. To minimize the was started in 1988 on air quantity of material that must be treated to recover this plutonium, sparging because with this and thereby minimize waste from the recovery process, plutonium process any pyrophoric material is concentrated into a fraction of the volume of the residue salt by would be converted into a more oxygen sparging. The major portion of the salt is thereby made inert oxide. In the course of suitable for discard. Concentration of the plutonium is accom- these experiments, it was noted plished by oxidation of the soluble chloride species into an in- that even further plutonium was soluble oxide species. Chemical reactions of interest are as follows: being recovered than before. Literature* surveys revealed that 2PUC4 + 202—> 2PU02 + 3C12 oxygen sparging work had been conducted as early as the 1960s. 2PUC13+ 02 —> 2PUOC1 + 2C;

2PUOCI + 02 —> 2PU02 + C12 * L.J. MullinsandJ. A. Leary, “MoltenSaltMethodofSeparationof AmericiumfromPlutonium,”U.S PatentNo.2,420,639(1967).

74 Nuclear Materials Technology Division Annual Review “Oxygen sparging has now almost completely replaced calcium salt stripping as the method ofchoice for treating electrorefi”ning salt residues.”

Oxygen sparging has under- Plutonium oxychloride is more easily handled in the aqueous gone several modifications and hydrochloric acid recovery process. In 1991, work was started on indeed continues to evolve as efforts to maximize plutonium oxychloride production with respect information and experience to plutonium dioxide. This effort resulted in a closer look at the gained are applied towards chemistry and kinetics of the oxygen sparging process. The first process optimization. However, thing that became clear was that the product is not at chemical the basic process has remained equilibrium because plutonium metal and plutonium dioxide cannot the same. coexist in chemical equilibrium. Depending on the limiting reagent, This basic procedure typically the equilibrium products of a mixture of metal and dioxide should results in a multilayered prod- be either metal and i3-plutoniumsesquioxide or cx-plutonium uct. At the bottom of the cru- sesquioxide and plutonium dioxide. Another mystery was the cible can be found metallic location of plutonium oxychloride in a layer below plutonium plutonium, usually poorly dioxide. Because plutonium dioxide has a density of 11.5 g/cc, coalesced. Above the metal is a significantly higher than that of plutonium oxychloride at 8.8 g/cc, solidified “black salt” matrix it should sink to the bottom of the molten salt. layer that contains plutonium In order to overcome the perceived kinetic barriers to the reaction dioxide, plutonium oxychlonde, between plutonium and plutonium dioxide, a procedure for stirring and plutonium metal. Above was added to the basic process. The anticipated chemistry was this black layer is usually a brownish layer of plutonium Pu + 3PU02 —> 2P~03 dioxide that is considered part of the “black salt” layer. Finally, Pu,O, + CaCl, —> 2PuOCI i- CaO the uppermost layer that makes up 5070to 75’%oof the bulk Pu,O, + 2NaCl —> 2PuOCI + N~O. volume is the “white salt” that contains only very small Stirring did indeed eliminate plutonium dioxide in cases where amounts of plutonium and there was a metal excess. The product typically consisted of a well- is suitable for discard. coalesced metal button, a “black salt” layer (plutonium oxychloride) that had a pronounced blue-green color, and a “white salt” layer.

Chloride Recovery 75 Oxygen Sparging (continued)

The chemistry occurring during stirring in the case of calcium found below the oxide layer chloride salts was as expected. However, in the case of sodium even though it is much less chloride, the actual chemistry is dense than plutonium dioxide. Furthermore, the variability of Pu + PuO, + 2NaCl —> 2Na + 2PuOC1. the size of the oxide layer can be understood because it is a func- After stirring, a second oxygen sparge oxidizes the pyrophoric tion of the amount of metallic sodium that deposits on the furnace head. uncoalesced plutonium metal in Oxygen sparge experiments on clean calcium chloride salts the electrorefining salts that containing pure plutonium trichloride revealed that onIy plutonium seems to vary widely. dioxide is produced when plutonium trichloride reacts with oxy- gen. The large amounts of plutonium oxychloride in oxygen- Future Work sparged electrorefining salts can be attributed only to the presence An improvement to the of pIutonium metaI in those saIts. A possible reaction scheme that process will be made by adapt- explains experimental observations has been theorized below. ing a chlorine spectrophotomet- When the salts are first melted, some coalescence of metal occurs, ric in-line detector developed for but a large fraction of elemental plutonium remains suspended in a multiple cycle direct-oxide %lack salt” layer. After sparging is initiated, plutonium dioxide reduction, thereby providing begins to precipitate and initially is intimately mixed with pluto- real-time analytical capabilities nium metal in the black salt layer. Some of the plutonium dioxide for detecting chlorine. A by- will be in sufficiently close contact to react and produce plutonium product of the oxygen sparge oxychloride. Although the mixture is probably not adequate to process is chlorine, and a dimin- cause a complete reaction between all the precipitated oxide and ishing concentration of this metal, some of it will be in sufficiently close contact to produce chemical substance in the off-gas plutonium oxychloride. As the sparging continues and plutonium stream will signal completion of dioxide continues to precipitate, the %lack salt” layer becomes so the run. Eventually this detector viscous that plutonium dioxide begins to pileup on top of the will be connected to a computer “black salt” layer. This is the oxide layer that was usually observed that will automatically terminate in traditional oxygen sparging. The material in the “black salt” oxygen flow. layer is a mixture of plutonium metal, plutonium oxychloride, and plutonium dioxide. These have all been observed by powder x-ray diffraction. This scheme explains why plutonium oxychloride is

76 Nuclear Materials Technology Divfdon Amud Review Fig.1.Closed-looprecyclingsystem.


MSE El n Lm;R

Plutonium oxychloride is Molten salt extraction is envisioned as a baseline process for easier than plutonium dioxide to Complex 21. Residue salts from this process contain dissolved recover by aqueous chloride plutonium trichloride but very little metal. Because oxygen methods. This was the initial sparging requires plutonium metal as a reagent to produce pluto- impetus for optimization of nium oxychloride, oxygen sparging would not be a process of plutonium oxychloride produc- choice for the closed-loop recycling system described above, but a tion. There is now another similar process could be used. Instead of using elemental oxygen to reason for producing a homoge- produce a plutonium oxide species, calcium oxide can be used neous plutonium oxychloride according to product. If plutonium trichlo- ride can be produced from PuC~ + CaO —> PuOC1 + CaC12. plutonium oxychloride, then a closed-loop recycling system can There is no oxidation agent in this reaction; therefore, plutonium be setup as shown in Fig. 1. If must remain in the +3 oxidation state, and no plutonium dioxide the conversion step can be will be produced. With calcium chloride salts, all the compounds accomplished with a minimum are soluble except plutonium oxychloride, so a clean reaction can be of waste generation, then this expected. In several successful experiments that used sodium closed-loop system will lower chloride/potassium chloride salts, calcium oxide remained in the overall waste generation associ- “black salt” layer. An issue that must still be addressed is ameri- ated with plutonium trichloride cium separation. synthesis and recovery. J?relimi- To produce plutonium trichloride from plutonium oxychloride, nary experiments using ammo- americium must first be separated. Otherwise, unacceptably high nium chloride to convert pluto- levels of radiation exposures will be encountered. Separation does nium oxychloride to plutonium occur with oxygen sparging where the americium remains in the trichloride are very encouraging. “white salt.” We have not yet explored americium separation with calcium oxide. +

Chloride Recovery 77 CHLORIDE RECOVERY

Materials Development for Pyrochemical Applications in the Weapons Complex Reconfiguration by Keith M. Axler NuclearMaterialsProcessingGroup:ChlorideSystems

Introduction Specifically, this testing com- Each pyrochemical process Currently, a large contribu- bines the abilities to conduct performed in the weapons tion to the volume of contami- experimental work both with complex presents a different nated waste is from nonreusable reactive gases and with salt and set of materials requirements. crucibles and ancillary furnace alloy systems containing actinide Among other considerations, components that fail in service. elements. the criteria for materials selec- The objective of our work is to 2. State-of-the-art analytical tion are based upon the process identify alternative construction and metallographic capabilities thermal profile, chemical materials that will reduce waste in support of research on radio- composition, and the functions by providing extended service active materials are fully opera- of internal furnace components. and that will improve process tional at Los Alamos. Additionally, product purity quality by remaining nonreactive 3. NMT Division maintains specifications are carefully in the chemical system. the most advanced capabilities considered in materials selec- Compared with analogous for thermodynamic modeling of tion because of the strictly industrial studies, materials complex chemical systems. defined tolerances for specific development for plutonium Computer modeling is used to elements in our product. applications presents exceptional evaluate potential candidate An evaluation process has considerations because of the materials from a standpoint of been designed to use time and reactivity of plutonium and the chemical thermodynamics. resources and to obviate unnec- hydroscopic salts. With an Thermodynamic modeling also essary experimental use of extensive array of capabilities, serves in process optimization plutonium. This is accom- the Nuclear Materials Technol- studies to identify effects caused plished through a demonstrated ogy (NMT) Division at Los by variances in process condi- series of tests. Alamos is uniquely suited to tions. 1. First, an evaluation of conduct materials development current materials performance research in this field. Candidate Materials Evalua- is conducted. This often re- 1. The Los Alamos plutonium tion: Methodology quires examination of the final facility is the only currently The criteria for alternative product to characterize materi- operating laboratory equipped materials are defined by the als interactions. for complete experimental specific conditions of the se- testing of materials for pluto- lected process application. nium pyrochemistry.

78 Nuclear Materials Technology Oivlsion Annual Rwicw “...intlwexaminationof productmetalinplutonium electrorefi”ning,electronmicroscopyrevealedan oxychlon”de surfacephaseassoctitedwith theuncoalescedmetal.”

2. Computer modeling is 5. Finally, successful candi- In addition, failed compo- then conducted to determine the dates are then demonstrated nents are examined to identify viability of candidate materials in service application. This the mechanisms of corrosion based on system thermodynam- provides thoroughly docu- that define the microstructural ics. Computer models are mented performance for final properties desired in a viable constructed for each pyro- consideration. candidate. Materials selection chemical process and reflect the for the multiple cycle, direct chemical environments in which Evaluation of Current Materials oxide reduction of plutonium the candidates must perform. Performance. dioxide presents one example. 3. If positive results are Current incompatibilities Based upon the characteristic obtained in the modeling, “cold” between pyrochemical systems corrosion mechanisms of chlo- testing is conducted to partially and construction materials are rine gas and liquid plutonium, confirm the modeled predictions identified by studying the metallographic techniques were by compatibility testing without reaction products of the selected used to interpret their relative plutonium. This includes high- processes. Interactions with the contributions to the corrosion of temperature salt containment crucible or furnace hardware are internal furnace hardware. and thermal cycling tests. indicated by the appearance of This data narrowed the field of 4. If promising performance interfering species in the prod- candidate materials by establish- has been indicated in the initial ucts. For example, in the exami- ing required microstructural stages of the evaluation process, nation of product metal in characteristics. work will proceed with “hot” plutonium electrorefining, testing of the candidate. At this electron revealed an stage, small-scale exposure tests oxychloride surface phase are conducted with plutonium in associated with the uncoalesced chemical environments simulat- metal. This observation was ing actual service conditions. consistent with the partial reduction of components predicted by com- puter modeling.

Chloride RJXOvery 79 Materials Development for Pyrochemical Applications in the Weapons Complex Reconfiguration (continued)

Computer modeling Processes are modeled with Many candidates that appear System thermodynamic alternate materials for crucibles promising because of their calculations are used to provide and ancillary furnace compo- thermodynamic stability have a cost-effective initial evaluation nents.2~ The modeIing results been disqualified because of of candidates. Many proposed reveal possible side reactions their inability to maintain integ- containment materials have been with the crucibles or the hard- rity through a sufficient number disqualified by thermodynamic ware. Verification tests have of thermal cycles. Cold testing models and dramatic savings been conducted to establish the also includes salt release tests in realized by obviating experimen- viability of the computer modeIs. which compatibility with molten tal evaluations. These computer This involved the experimental pyrochemical salts is examined. models utilize rigorous calcula- confirmation of results obtained tions to predict equilibrium in the modeling.4 In addition to Hot Testing compositions based on free- utilizing these computer codes Experimental work with energy minimization for com- to evaluate candidate materials, plutonium is indicated only for plex, heterogeneous chemical they are used to model phase candidates that have performed systems. The models require equilibria in higher-order sys- well in the previous stages of the input in the form of Gibbs tems to aid in process optimiza- campaign. Small-scale crucibles energies for all possible species tion.5$ of the candidate material are and phases as welI as initial fabricated and tested by their use composition, temperature, and Cold Testing in the containment of liquid pressure. Large data banks,] Thermal cycling tests are plutonium and molten salt over which are updated on a continu- particularly valuable in the extended time. ous basis, provide the required evaluation of coated materials. Also at this stage, differential thermodynamic data. To date, we have examined an thermal analysis has been con- extensive matrix of refractory ducted to determine the rate and coatings, prepared by a variety extent of the candidate material’s of deposition techniques.7 reactivity with plutonium.8

80 Nuclear Materials Technology Divls!on Annual Revk.w References 1.T. L Barryetal.,MTDATA Handbook: “ The importance of minimizing radioactive waste Documentation for the NP.LMetallurgical and Thermochemical Databank, NationalPhysical volumes continues to promote interest in alternate Laboratory,Teddington,UK(1989). construction materials” 2.L.M.Bagaasenetal.,“Investigationsof CoatedRefractoryMetalsforPlutonium Containment,”Trans. Am. Nucl. Soc. 62,240- 241 (1990).

3. KM. Axler, “ReportonSpecial MetallurgicalProblems,”LosAlamos NationalLaboratoryinternaldocument NMT-3:91-164(1991). Demonstration work Summary Demonstration involves using The importance of minimiz- 4. K.M.AxlerandR.LSheldon,“The EffectofInitialCompositiononPuOC1 the candidate material to con- ing radioactive waste volumes FormationintheDirectOxideReductionof struct components used in continues to promote interest in PuO,;’JournalofNuclear Materials, ~ 183- actual pyrochemical processing. alternative construction mater- 185,1992. Currently, several candidates are ials. As work continues in this 5. A.M. Murrayetal.,“Thermodynamic under evaluation in this ad- area, we will develop a suite of ModelingandExperimentalInvestigationsof theCsC1-Ca~-PuCl,System,”RockyFlats vanced stage of materials materials for pyrochemical technicalreleaseRFP-4480,presentationat selection: operations that will provide theThird Int. Symp. Molten Salt Chem. and 1. Carbon-saturated tantalum extended service without com- Techrol., Paris,France,July1991. is being tested for use in the promising product quality. 6. K M.Axleretal.,“CalculatedPhase multiple cycle direct oxide As part of our investigations, EquilibriafortheCaC~-KCl-MgC~System,” reduction process. This material we are collaborating with scien- NPLreportDMM(D) 123, National Physical Laboratory, Teddington, UK (1991). will also be tested in advanced- tists in related fields to remain concept electrorefining and in apprised of current develop- 7. K. M. Axler, Los Alamos National the americium extraction process ments in advanced materials. Laboratory internal document NMT-3:91-144 (1991). performed on aged plutonium. One example is the recent indus- 2. Silicon nitride is being trial collaboration with W.R. 8. K. M. Axler and E. M. Foltyn, “High- Temperature Materials Compatibility Testing tested for use in reactive gas Grace & Co. and CERMET on the of Refractory Crucible Materials: TaC, Y20J, sparging during the in situ advanced processing of thorium- YzOj-coatedMgO, and BN,” Los AJamos regeneration of spent salts. based ceramics.9 Other joint National Laboratory report LA-11586-MS (September 1989). 3. High-density yttria is investigations have included being used in plutonium studies of engineered materialsl” 9. R Brezny, R. W. Rice, and K. M. Axler, and refractory ceramics” “Thoria: A Candidate Material for Use in electrorefining. Pyrochemical Processing,” presentation at the Other materials are at more involving scientists at Lawrence 1992 Ann. Meet.Am. Ceram. Soc., April 1992. preliminary stages of evaluation Livermore National Laboratory, for selected applications. These Westinghouse Savannah River 10. KM. Axler, G. D. Bird, and P. C. Lopez, “Evaluation of Corrosion Resistant include carbon-saturated nio- Laboratory, and Westinghouse Materials for Use in Plutonium bium and yttria-stabilized Science and Technology Pyrochemistry,” Proc. 180thMeet. zirconia. Center. + .Hectroclrem.Soc. (1991). 11. P. C. Lopez et al. “Investigation of Silicon Nitride Performance in Plutonium Systems for Application in Pyrochemistry;’ Los Alamos National Laboratory report LA- 12322-MS,1992. ChkidelZemv5y 81 CHLORIDE RECOVERY Pyrochemical Integrated Actinide Chloride Line (PINACL) by James A. McNeese NuclearMaterialsProcessingGroup:ChlorideSystem

NMT-3 has identified a need Our current pyrochemical The design and reconfigura- to develop a glove box process process facility was developed tion will be done by stages. First, and development facility, the for production support through- we will specify general glove box Pyrochemical Integrated Actin- put and not as a development/ conditions for atmosphere, work- ide Chloride Line (PINACL), as demonstration facility. Some of station size, material transport a means of totally integrating the glove boxes were transferred systems, utility needs, and esti- pyrochemical process technol- from TA-21 after several years mated floor-space usage. The ogy. This versatile system will of use and then installed into resultant design will be a modu- facilitate process development TA-55. With the changing lar glove box system. This modu- and technology enhancement for missions and modes of operation lar concept will allow enough processes that will be included at TA-55, the present facility is versatility to continually change or have the potential for inclu- not adequate for present priori- the configuration of the layout sion in the Complex 21 ties, which include process (removing and replacing glove reconfiguration effort. PINACL development and demonstration boxes) to meet the needs of will include design features for Complex 21, development of projects and demonstration goals. minimizing space requirements, new methods for pyrochemical We are beginning the conceptual personnel exposure, and waste separations, basic chemistry design of the project. Design, generation while maximizing investigations of current pro- fabrication, and installation will personnel efficiency, material cesses, and development of take several years to complete. throughput, process reliability, diagnostic techniques for molten Facility integration is closely safeguards and security, and salt systems. We are designing a tied to process chemistry integra- safety. Process automation will versatile process facility that will tion efforts. Pyrochernical pro- be used where beneficial. State- adequately test chemistry, cessing has always had the goal of-the-art analytical nondestruc- equipment, and processing of becoming a stand-alone opera- tive array equipment for moni- techniques for pyrochemical tion that would treat all of its toring and controlling the pro- processes and that will incorpo- residues and recycle its reagents cess will be incorporated into the rate automation testing facilities to reduce dependence on the design. This facility will be used within the facility. aqueous recovery processes. as a test bed for bench-scale through production demonstra- tion for pyrochemical processes and processing techniques.

82 Nuclear MatwialsTcchnology DivMon Annual Revkw “PINACL will include design features minimizing space requirements, personnel exposure, and waste generation while maximizing personnel efficiency, material throughput, process reliability, safeguards and security, and safety.”

Historical pyrochemical opera- Our approach is to develop Success of the concept will tions used different salt systems equipment that is compatible depend on the actual process ‘ and process chemistries for each with use of the salt product from efficiencies and product purities individual process. Currently, MCDOR and to demonstrate the from the systems. Finding a we are perfecting a common salt feasibility and effect of this salt method of shaping the regener- system that will tie all the in the other operations. From a ated salt is also a topic that will pyrocemical operations together gross chemistry standpoint, be addressed. The feed salt to into an integrated system. there is no difference in recycled the ER process is presently a cast Studies for several years have salt, but small impurities re- cylinder that is smaller than the shown that calcium chloride can moved from the salt during the MCDOR crucible. Methods for be used in the molten salt extrac- reduction step in the MCDOR casting the salt after regeneration tion (MSE) process and, in the process may contribute to salt or a method for loose-salt- electrorefining (ER) process. behavior differences. loading into the ER cell will be The major pyrochemical salt The salt from MCDOR is developed. In the interim, salt user has been calcium chloride enriched in calcium chloride will be loaded as pieces into an in direct oxide reduction (DOR). because initial impurities are ER cell and melted. Additional This process has been improved reduced into the product metal salt will then be added to the and now is the present multiple during the first reduction. As molten salt. cycle direct-oxide reduction the salt is reused, some impuri- Chemistry-based concepts are (MCDOR) process that is a net ties are introduced from corro- also being combined with equip- calcium chloride generator. sion of the equipment and ment-based integration schemes. Salt produced in the MCDOR occasionally the salt product is In addition, process systems can process can be used in MSE and completely friable and does not and will be combined in future ER because each process has hold a cast shape. These con- development efforts. A recent been demonstrated using the cerns must be addressed by example of this concept has been calcium chloride system. determining the cause and the new initiative to combine effect of the observed behavior. separate Complex 21 processes Process and product purity data into one operation. This opera- will be collected and analyzed tion will combine several differ- when the tests are completed on ing process chemistries so that the MSE and ER processes using we can take advantage of the salt from the MCDOR process. consecutive processing sequence.

Chloride Recovery 83 Pyrochemical Integrated Actinide chloride Line (PINACL) (continued)

The individual processing steps The benefit will be to develop a are combined into a sequential system of processes that can be single-location processing flow demonstrated as a module and array that will minimize han- that can be inserted into the dling operations, waste genera- design of the Complex 21 flow tion, and operator exposure. sheet while using less floor and Automation techniques will be glove box space for a separate applied to repetitive operations processing flow sequence. + where feasible. The intent of this project is to address a pertinent Complex 21 mainline processing sequence and to develop han- dling techniques and operational flows into a coherent whole.

84 Nuclear Materials Technology Division Annual Review w ASTE MANAGEMENT Waste Management Overview by Larry R. Austin NuclearMaterialsProcessingGroup:NitrateSystems

Introduction In addition, discharges from this 2. The waste management All waste streams generated facility must meet the federal location has several steps wheree in the site return, recovery, and Clean Air and Water Act, and acceptable technologies, have manufacturing areas are sent to solid waste shipped off site must been shown to be “production the waste management area. meet transportation and Waste ready” but do not exist today. The waste management part of Isolation Pilot Plant Waste 3. The waste management the baseline flow sheet is divided acceptance criteria. location has numerous operating into two main areas. The first Flow sheet Considerations steps as shown by the number of waste management area handles The waste management part boxes on the flow sheet. the liquid wastes, and the second of the flow sheet has been one of 4. Within the DOE complex, area processes and treats solid the more difficult parts to fewer technology development wastes. develop for several reasons. programs are aimed at solving As a rule, processing opera- 1. The development of the some of these difficult problems. tions that would involve the flow sheet depends, to some On the positive side, for most recovery and recycle of usable extent, on the amount and type of the waste management flow materials would not be a part of material that is being sent to sheet, the operations are rela- of the waste management area. the waste management area. tively straightforward, and the These operations would be The feed streams to the waste development programs are included in the appropriate part management location are the under way. of the site return, recovery, or discharges from the manufactur- manufacturing areas. Waste ing, site return, and recovery management is one of the more areas. Thus, the flow sheet for critical areas: All materials these sites must be sufficiently processed in this area must developed to define discharges comply with all DOE, state, and so that the technical details of the federal treatment, storage, and development programs in the disposal regulations. waste management flow sheet can be addr%sed.

Waste Management 85 Waste Management Overview (continued)

Critical Flow Sheet Concerns There are numerous alterna- Also, radiolysis might generate On the baseline flow sheet, tives and backups for CAI, but hydrogen gas that can push free the areas of critical technological one of the problems is that none liquid from the cement matrix concern for waste management of the alternatives would replace and rew.dtin surface water. are the destruction of waste CAI dh-ectly. For example, Of the several alternatives to organics and the immobilization existing methods for destroying cementation, none are now of residues and liquids for hazardous liquid organics would “production ready.” shipment to WIPP. The tech- not perform very well on solid Four technical areas will be nology of choice for destroying organic waste. Therefore, tech- highlighted with feature articles waste organics is controlled air nology development for destroy- under the waste management incineration (CAI). The major ing organic waste is made more section. These are super criticaI reason for the technical uncer- difficult. water oxidation, waste stream tainty is concern over the ability The second major concern is monitoring, and waste stream of sites to obtain licensing and immobilization or fixation. The polishing (removal of heavy permits for CAI. Several sites baseline technology for fixation metals). + are planning to obtain licenses is cementation. This process is and permits to perform CAI, but very sensitive to the composition if these efforts are unsuccessful, of the material to be immobi- the Complex 21 facility would lized. If the cement sets too not be able to operate. rapidIy, the cement can easiIy dewater after a few months.

86 Nuclear Materials Techn&gy Division Annual Review WASTE MANAGEMENT Destruction of Hazardous Wastes by Supercritical Water Oxidation by Steven J. Buelow PhotochemistryandPhotophysicsGroup

Introduction Under these conditions, In principle, any organic Supercritical water oxidation water is a fluid with densities compound—that is, any com- (SCW()) is a relatively 10w- high enough for reasonable pound composed of carbon and temperature process that de- process throughput to be other elements such as hydro- stroys a wide variety of hazard- achieved, but its transport gen, nitrogen, , ous chemical wastes effectively properties are like those of a sulfur, and the halogens— can and efficiently. It is applicable gas, allowing rapid chemical be completely oxidized to rela- to the destruction of most or- reaction. tively innocuous products. ganic compounds and some Supercritical water is a Because water is the reaction inorganic and therefore could unique solvent medium in medium, the process can be used be used to destroy toxic organic which oxidation can take place for a variety of organic wastes waste and to treat contaminated at temperatures lower than containing water or for water water, soil, and sludges. A those of incineration, limiting contaminated with organic SCWO system can treat aqueous the production of unspecified compounds. The optimum streams containing organics in nitrogen oxides and char. The concentration of organic com- relatively low concentrations reaction is carried out entirely pound in water depends on the (dO%) and offers complete in an enclosed pressure vessel heats of oxidation of the particu- control over emissions, thus containing dilute reactants, so lar organic compounds present meeting the Environmental that the heat of reaction is ab- and the engineering design of Protection Agency’s concept sorbed by the solvent and the the apparatus. An engineering of a “totally enclosed treatment” temperature can be maintained tradeoff to be considered in the facility. at any desired level, typically in design of a plant is the organic In SCWO, the waste is mixed the range of 400”C to 650”C. concentration that generates with an oxidant (oxygen, air, or Rapid oxidation occurs within enough heat to maintain the ) in water at seconds or minutes and pro- reaction but not more heat than pressures and temperatures duces simple products (ideally, can readily be removed from the above the critical point of water carbon dioxide, water, and processing vessel. (374°C and 218 atm). nitrogen).

Waste Management 87 Destruction of Hazardous Wastes by Supercritical Water Oxidation (continued)

Pure or highly concentrated This work evaluates reactor AIl effluents can be contained organic wastes can be diluted design, determines destruction and collected so that they can with water. Conversely, fuel or efficiencies and products of be tested before release to the other organic wastes can be destruction, and models chemi- environment; unreacted oxygen added to contaminated water. cal and physical processes in can be segregated and recycled, Other factors that influence the supercritical water. Some of our and energy can be recovered and engineering design include the results concerning reactor opera- used to heat incoming waste. residence time in the reactor tion for several waste streams, in A number of different reactor (determined by the chemical particular, mixing of organic designs have been proposed and kinetics of oxidation of the wastes and oxidizers, destruc- put into practice, including both waste), the physicaI state of the tion of explosives, and treatment vessel and tubular reactors. waste and its oxidation products, of Hanford waste simulants are A great range of sizes appears and the amounts of waste to be summarized here. to be possible for SCWO plants. processed. Standard pressure-vessel tech- Our current research at Los Reactor Design and Operation nology can be used to provide Alamos National Laboratory A general schematic for an both small mobile units and aims to determine the advan- SCWO reactor is shown in Fig. 1. permanent medium-sized tages or problems with using The waste, oxidant, and fuel surface installations for process- SCWO to treat high-risk wastes. (if needed) are compressed, ing of laboratory or manufactur- Such wastes include explosives, preheated, mixed, and injected ing wastes. Plants with very propellants, and the complex into the reactor, which ideally large capacities have also been mixed wastes found in the converts the waste to water, proposed. These plants consist underground storage tanks at carbon dioxide, nitrogen, salts, of a cylindrical heat exchanger Hanford, Washington. and insoluble solids. The reactor and reaction vessel emplaced in temperatures and pressures are the ground by using oil-field typically 400”C to 650”C and 250 drilling technology. to 350 atm. The solid, liquid, and gaseous effluents are sepa- rated, depressurized, and if needed, post-processed.

88 Nuclear MateAals Technology Divlslon #mmJa) Review Fig. 1. SimplijSedschematic of supercritical water oxidation unit.

- Power Water Cooling supply

Waste/ Reactor Water 400-650”C Heat Exchanger 250-350 atm.

L Solids Preheater a Separator I Accumulator

Gas Liquid r Remote Computer Separator Control H20 E 7 Pump ?

To date, our experiments Temperatures are measured The total flow was 1 gaL/h at have examined tubular reactors. using thermocouples attached 273 atm. The acetone concentra- Our largest SCWO unit has a to the outside of the reactor tion after mixing was 2 wt’YO, capacity of 50 gal./day, is tubing. For the test shown in and oxygen was present at twice transportable, and operates by Fig. 2, the acetone/water and the stoichiometric concentration remote control by computer.’ oxygen/water feed streams needed to convert the acetone to All important operating param- were mixed and then heated to carbon dioxide and water. At a eters, such as temperature, the desired temperature by distance of 10 ft, a temperature pressure, and flow rate, are direct, electrical-resistance plateau occurred (Fig. 2) because continuously monitored and heating of the first 20 ft of the of the behavior of water near the recorded. The unit is modular reactor; heaters on the last 35 ft critical temperature. In this so that reactors of various of the reactor helped to balance temperature range, the heat designs can be easily inter- conductive heat losses. capacity of water is relatively changed. Fig. 2 shows the large, and the temperature rise temperature distribution along decreases with constant heating. a 55-ft-long tubular reactor measured during a test using acetone as a surrogate waste.

Waste Management 89 Destruction of Hazardous Wastes by Supercritical Water Oxidation (continued)

800 i Fig. 2. Renctor-tube te)nperuturcas a function of distance from the reactor inlet under steady-state eonditious. The total flo7uwas1 gaL/h at 273 afn;. The ncefone concentmfion nfter nlixitlg was 2 zut%,and oxygen wns present at fu)jce the stojchio~jlefricconcentration needed to convert the ncetone to carbon dioxide wzdwater.

o 10 20 30 40 50 Axial Distance(ft)

At a distance of about 15 to 20 ft Analysis of the aqueous effluent Hexane, oxygen, and water are (450”C to 700”C) the reaction rate yielded a destruction efficiency not miscible at low temperatures of acetone with oxygen in- for acetone of 99.99985% under and in the subcritical portion of creased, and the temperature these conditions. the reactor, they remain sepa- rose more rapidly because of the Mixing the waste and oxygen rated into three phases, produc- energy release from the oxida- before heating the fluid is conve- ing an explosive mixture. This tion reaction. The lack of further nient and allows the oxidation problem does not occur when temperature increase after 20 ft reactions to begin at lower the waste/water and oxidizer/ indicates that most of the oxida- temperatures (which may dimin- water streams are heated above tion reaction was complete and ish pyrolysis reactions). How- the critical temperature before that the temperature slowly ever, it is not safe to do so for all being mixed. decreased from the heat loss wastes. Similar tests using 2’%0 Figures 3 and 4 show the through the reactor insulation. hexane solutions produced temperature distributions along Because the reactor was not detonations in the first several a reactor with separate preheater cooled, the maximum tempera- feet of the reactor and in a room sections for the waste and oxi- ture is determined by the heat temperature filter located up- dant under steady- state condi- content of the waste and the heat stream of the reactor. tions. The preheater are 12 and capacity of the fluid. A heat 13 ft Iong for the feed streams, exchanger at the end of the and are heated by direct electri- reactor rapidly cooled the efflu- cal resistance. Oxidation occurs ent to ambient temperature. in a 6-ft insulated tube following the mixing region.

90 Nuclear Materials Technology Division Annual Review 700 Fig. 3. Reactor-tube temperatures as a @CfiOn ofdisfance from the oxygen 600 preheater tube inlet. The totalfi’owwas ~ 500 Mixed lgal./h at 248 atm. The acetone concen- 0- fration after mixing was 3 wt’%,and P3 400 ,-S------:-:-.-*.-J oxygenwas present at twice the Hexane - -z--— @ ,/’ . H %—- - .stoichiometricconcentrationneeded to 8 300 F 1 .,~’O,xygen convert the acetone to carbon dioxide /’ - and water. s~(jo ;’ ,) t’ / 100 ,’” /’ ~ ,’ /

700 1 Fig. 4. Reactor-tube temperaturesas a function of distance from the oxygen preheater tube inlet. Thetotalftowwas ~ 500 1.1 gal./h at 253atm. The acetone 0 concentration aftermixingwas2,5 _] --——. ,-,---<,/ ------, g 400 + .Ar-ntnnn ------./ wt%, and oxygen was present at 1.5 .“” .”,,” --- $ ,8,------times the stoichiometricconcentration g 300 ,/’ Oxy~en needed to convert the hexane to carbon g ‘i ,,,,’ , / dioxide and water, + 200 /’ ,/’ / 100 1 /“ ,’ ,,’ // o I I I I I I I I 1 I 1 0 2 4 6 8 10 12 14 16 18 20 AxialDistance(R)

For tests using acetone (Fig. 3), At mixing temperatures below to determine which materials we heated the acetone and 450”C, a temperature increase can be safely mixed in the sub- oxygen feed lines above 450”C after mixing did not occur and critical region. However, we before mixing in order to initiate acetonewas not effectively suspect this may be a problem a rapid oxidation reaction. The destroyed. The hexane oxidation only for volatile, water-insoluble, heat of reaction released after rate was noticably faster. For flammable organics such as mixing increased the fluid hexane, the temperature reached hexane. Furthermore, the prob- temperature from 450”C to a maximum only 4 in. after the lem may not occur when air is 650”C within 12 in. of the mixer mixer. used as the oxidant because a and produced rapid and com- Thus far, we have not tested pure oxygen phase will not be plete destruction of the acetone. a wide range of organic wastes present in the subcritical region.

Waste Management 91 Destruction of Hazardous Wastes by Supercritical Water Oxidation (continued)

TabIe I. Results for the SCWO Explosive

PETN RDX TNT NQ Initial cone. (ppm) 3.8 2.6 35.2 65.5 1700. Destruction efficiencies >0.9825 >0.99 >0.9992 >0.9998 >0.9999 NO~a 0.187 0.124 0.101 0.366 0.0003 NO: 0.060 0.053 0.141 0.285 0.0004 aGiven as fraction of initial nitrogen.

Destruction of Explosives We have investigated the used as the oxidizer and was The traditional disposal feasibility of oxidation in mixed with the feedstock methods for explosives are open- supercritical water as an alterna- containing explosive before the air burning and open detonation. tive method for the destruction fluids were heated, In all cases, Regulatory agencies, however, of explosives and propellants.2 the oxidizer was in excess of are likely to prohibit these In Table I, the destruction effi- that needed to convert the methods because of the associ- ciencies for five explosive com- explosive to carbon dioxide, ated uncontrolled air emissions, pounds—pentaerythritol water, and nitrogen. Typical in particular the huge quantities tetranitrate (PETN), experimental conditions were of unspecified nitrogen oxides cyclotetramethylene pressures near 340 atm, reactor that are commonly formed. In tetranitrarnine (HMX), temperatures near 600”C, and addition to conventional forms cyclotrimethylene trinitramine residence times near 7s. For all of explosives wastes, soils and (RDX), trinitrotoluene (TNT), of the explosives investigated, groundwater at manufacturing and nitroguanidine (NQ) in the aqueous effluents did not plants and military bases have supercritical water—are given contain detectable amounts of been contaminated with explo- along with the fraction of the explosives. The measured sives from normal operating initial nitrogen converted to destruction efficiencies were procedures. Incineration with nitrate and nitrite in the Iimited by the sensitivity of the the associated air pollution may aqueous effluent. The initial analysis method (50 ppb) and be used for decontamination of concentrations of the explosives the low initial concentration of such soils, but few satisfactory were kept Iow, less than half the explosives, Carbon dioxide and economic methods exist for their room-temperature solubili- and nitrous oxide were identi- decontamination of ground ties, to prevent precipitation and fied in the gaseous effluents water. accumulation of explosive mate- using Fourier transform infra- rial in the feed line; leading to the red s-pectroscopywith a reactor. Hydrogen peroxide was mult~passwhi~~ceil.

92 NuclearMatwialsTechnolo~Divis[onAnnualIklcw Fig. 5. Reacfion of TATB in water. The pressure rise because of the heating of fhj water has been subfracfed.

80 13


Carbon monoxide, , , and nitrogen diox- 40 ide were not observed. We estimate detection limits for these species as a fraction of starting weight to be 0.1 for 20 PETN and HMX to 0.005 for NQ. It is interesting to note the wide variation in the fraction of initial nitrogen that is converted to 0 nitrate and nitrite ions. For TNT, the amount of nitrogen con- verted to nitrates and nitrite is 260 280 300 320 340 over 60’%0,whereasfor NQ it is Temperature (oC) less than 0.1%. The amount of nitrate and nitrite produced also The first approach uses To determine the pressure rise varies with reactor temperature slurries to continuously feed caused by the rea;tion of the and oxidizer concentration. This high concentrations of explosives explosive, a baseline test using an chemistry is being investigated into a supercritical water reactor. equal quantity of water in the further in order to minimize To evaluate the hazards associ- absence of the explosive is per- nitrate and nitrite production. ated with heating slurries above formed. The difference in the Destroying explosives using the critical temperature, we are measured pressures at a particu- SCWO at concentrations at or examining the behavior of small lar temperature for the two tests below the volubility limits is not pzuticlesof explosives as they is the pressure of the gases pro- practical except for the treatment are heated in water. These duced by the reaction of the of contaminated ground water. experiments are performed explosive. This pressure differ- In order to increase the through- using a small batch reactor ence gives a qualitative measure put of the destruction process for (200pi). A small quantity of of both the extent and the rate bulk explosives, other methods explosive is added to 100 ml of of the reaction of the explosive. for introducing the explosives water, with the balance of the Fig. 5 shows preliminary into the supercritical water reactor volume filled by air. results for the behavior of reactor are being developed. The pressure is measured at 1-s triaminotrinitrobenzene We are currently investigating intervals as the reactor is heated. (TATB) as it is heated. two alternatives.

WasieMamgment 93 Destruction of Hazardous Wastes by Supercritical Water Oxidation (continued)

For small quantities (<7 mg) of We then processed the products SCWO has been identified as TATB, the reaction proceeds of the hydrolysis through a an attractive method of slowly as the water is heated, supercritical water reactor, nonselectively destroying the producing a controlled release of producing carbon dioxide, organic components of the energy. For quantities greater water, nitrous oxide, and nitro- complexant concentrate waste than 13 mg, the reaction starts at gen. For HMX and NQ solutions before that waste is fed into the slightly higher temperatures but with starting concentrations Grout Treatment Facility or the proceeds much more rapidly. between 1 and 8 wt%, this two- Hanford Waste Vitrification In the 8-to-10-mg range, the step treatment produced over Plant Feed. behavior is not reproducible and 99.99970destruction of the Although SCWO has been probably depends on the mor- explosive and less than 1 ppm proved efficient for the removal phology of the particle. These total organic carbon (TOC) in the of organic matter, the ability to preliminary results indicate that liquid effluent. We are examin- treat highly concentrated inor- the behavior of the slurries may ing the possible problems, such ganic waste streams has not been vary and that the slurry particles as self-heating, associated with fully demonstrated? In the case can react rapidly. Such uncer- hydrolyzing large pieces of of the Hanford tank wastes, tainties raise concerns about explosives. Thus far, none have thermodynamic calculations using slurries to feed been encountered. show that the nitrate already supercritical water reactors. present in the wastes can serve The second method for as an oxidant for organics and introducing large quantities of Treatment of Hanford Waste other oxidizable compounds explosives into a supercritical Simulants such as ferrocyanides. Prelimi- water reactor involves process- Storage tanks at the Hanford nary experiments indicate that ing the explosive by hydrolysis reservation in Washington nitrate may be an acceptable at ambient pressures and low contain millions of gallons of oxidant for other components of temperatures (50°C to 100”C). mixed wastes composed of the waste. Thus far, we have demonstrated highly concentrated soluble that NQ, HMX, and nitrocellu- inorganic compounds and Iose can be decomposed rapidly organic components. into water-soluble nonexplosive products through hydrolysis under basic conditions.

94 Nuclear Materials Technulcgy Division Anntul Revkw Fig. 6. Schemafic of SCWO reactor check with salt separator. valve

relief valve Feed Heated Reactor Pump 1/4” OD, 0.083” wall 2 ft. long alloy C276.


HeatedSalt-Separator filter, 140 p 48 CC wire mesh 316L SS 150 cc cooling Surge Vessel/ water Sample 1 Reservoir . . Reactor*Dump Collection

To explore the feasibility A schematic of the apparatus During the experiment, the of SCWO treatment of the used for this experiment is effluent was collected and Hanford tank wastes, a simu- shown in Fig. 6. The heated measured for volume and pH. lant was prepared and treated. portion of the reactor consists At the end of the experiment, The constituents of the of a short linear tube that flows the reactor tube was drained into simulant (Table II) are mainly into a heated salt separator. the salt separator. The separator sodium nitrate (5 wt%), with The reactor is mounted verti- was then cooled and the contents some organic matter (sodium cally so that precipitating solids collected. The system was acetate and EDTA), other will settle into the separator. washed with water, followed sodium salts (chloride, sulfate, The mass flow rate was 7 g/ by a 1.0 N sulfuric acid solution. and bicarbonate), heavy metals rein, producing a 51-s residence Finally, solids were filtered from (chromium and nickel), alumi- time in the reactor. The forma- the rinse solutions, dried, and num nitrate, and nuclides of tion and breakdown of plugs weighed. concern (cesium and during the experiment pro- strontium). duced some temperature and pressure fluctuations at about 508°C and 286 atm.

Waste Management 95 Destruction of Hazardous Wastes by Supercritical Water Oxidation (continued)

Table II. Results of Hanford Waste Simulant Processing

Experiment/ Feed Effluent Brine Rinse Rinse Solids Constituent Water Acid mg/1 mg/1 mgll mgll mg/1 l-w Volume (L) ---- 0.347 0.023 0.202 0.206 ---- pH 7.0 6.3- 6.4 12.4 10.0 ------Cs 5.5 0.2 41.6 0.7 0.3 BDL Na 19100 71-72 254000 2360 473 BDL Sr 6.0 BDL 1.10 1.90 0.60 1240 Al 463 0.2 1800 20.8 20.4 24600 Cr 12.9 0.55-0.64 340 21 5.3 14.5 Fe BDL BDL BDL 0.9 12.5 1330 12.8 BDL BDL 6.20 5.70 193 N@N’ 37420 156-167 491000 3990 806 ---- 681 8.5 11300 85.7 ------N:! BDL 46-59 38600 382 ------Acetate 2220 1-3 100 211 ------TOC 4300 1-7 23 157 50 ---- TIC 4 75-127 0.1 203 0.1 ----

The results from processing The aluminum concentration This result is illustrated in Fig. 7, the Hanford waste simulant are was reduced by 99.95’ZOand the which shows the constituent given in Table II. The content of chloride concentration was distribution in the various the sodium, nitrate, and organic reduced by 98.7Y0. Most of the streams. The large fraction of matter in the effluent was constituents were recovered in the aluminum and strontium in reduced by over 99.5Y0 from the the brine. the solid phase suggests that feed. Strontium concentrations they formed insoluble aluminum in the effluent were below oxide and strontium carbonate. detection limits whereas the cesium concentration was reduced by over 96Y0.

96 Nuclear Materials TechnologyDivision AnnualReview Fig. 7. Partitioning of constituents for processed Hanford waste simulant.


. - -1 Ni Al N03. Na Cs Sr Cr cl Constituent

Chloride and bicarbonate most Aluminum and nickel were The results presented in this likely precipitated as sodium difficult to remove by rinsing and paper show that explosives such salts. The majority of the so- were not fully recovered. as HMX, PETN, RDX, TNT, and dium and cesium likely precipi- It is possible that oxides of these NQ can be rapidly destroyed by tated as nitrates. The pH of the metals caused the plugging. reaction in supercritical water. brine was quite high (12.4), The problems associated with possibly because of the precipita- Summary introducing large concentrations tion of sodium hydroxide and The use of SCWO to treat of explosives into a supercritical bicarbonate. The feed pH was hazardous wastes such as organic water reactor have not yet been 7.0 whereas the pH of the efflu- compounds, explosives, and fully solved. The use of slurries ents varied from 6.3 to 6.4. After mixed wastes has been investi- may be viable, but preliminary processing for 30 rein, plugs gated. This relatively low- experiments indicate unpredict- began to form in the heated temperature process has been able behavior. reactor tube, and the experiment proposed as a means of destroy- was halted after 50 min. ing both fuels and oxidants, with full control of effluents.

Was(e Management 97 Destruction of Hazardous Wastes by Supercritical Water Oxidation (continued)

Preprocessing the explosives Cesium was also efficiently References using hydrolysis in low-tem- removed (>90Yo),indicating a 1. R. D. McFarland, G. R.Brewer, and C K. Refer, “Design and Operational perature basic solutions has significant waste reduction and Parameters of Transportable Supermitical been demonstrated for NQ and the potential of SCWO for Water Oxidation Waste Destruction Unit,” HMX. A Hanford underground- activity reduction of the Los Alamos National Laboratory report LA-12216-MS(December 1991). storage tank waste simulant radiocesium in mixed wastes. was prccessed successfully Tests of different reactor designs 2. S.J. Buelow,R. B.Dyer, C. K-Refer, using SCWO. At temperatures showed that volatiIe, flammabIe J. Atencio, and J. D. Wander, “Destruction of Propellant Components in Supcrcritical near 500”C, over 99.5’%oof the organics that are immiscible in Water;’ Proceedings of JANNAFSafety and organic matter, sodium, and water can be safely processed Environmental Protection Subcommittee nitrate are removed from the in a supercritical water reactor. Workshop, Tyndall Air Force Base, Florida, March 27-28,1990,CPfA Publication 540, reactor effluent. The resulting Our results for hexane oxidation March (1991). waste brine (nearly 1.4 kg/liter demonstrate that separate of sodium nitrate) was less than preheating of such organics 3. T. T. Bramlette, B.E. Mills, K.R. Hencken, M. E. Brynildson,S. C. Johnston, J. M. Hruby, 3% (by volume) of the total and of the oxidant before H. C. Feernster, B.C. Odegard, and volume processed. mixing allows for safe and M. Modell, “Destruction of DOE/DP efficient destruction of the Surrogate Wastes with SuperCriticalWater organic compound. + Oxidation Technology;’ Sandia National Laboratones report SAND90-8229(1990).

98 Nuclear Materl.ds Technology Division Annual Review WASTE MANAGEMENT Waste Stream Monitoring by Rick Day Nuclear Materials Processing Group: Nitrate Systems

In light of the new regula- A Waste Stream Monitoring Characterization of the liquid tions and restrictions imposed on Program has been initiated waste streams (acid, caustic, and facilities for discharge or transfer using experts from NMT-2, industrial) that leave TA-55 is of liquid waste, the ability to NMT-3, NMT-7, NMT-8, and being performed by CLS-1. monitor, ensure SNM account- CLS-1 to address the technical The analyses being per- ability, and characterize waste challenges. The pro~am’s formed include streams is crucial. As a lead DOE emphasis is on 1. radiochemistry, facility for the development of 1. determining the volumes 2. trace elements using induc- special nuclear materials process of liquid waste generated at tively coupled plasma-emission technology, TA-55 has a respon- TA-55/PF-4 in a given time spectrometer (ICP-ES) and sibility to set a standard in the period; inductively coupled plasma- DOE complex for effluent moni- 2. identifying suitable sam- mass spectrometry (ICP-MS), toring and control for environ- pling techniques for representa- 3. ion chromatography to mental protection. Waste solu- tive sampling, accurate flow determine anions, and tions generated from plutonium measurements, temperatures, 4. chemical oxygen demand processing need to be character- and so forth; (COD). When instrumentation ized. Flow rates need to be 3. characterizing the compo- becomes available, total organic monitored to ensure regulatory sition of the various liquid waste carbon will replace COD. All the comliance and to confirm that a streams; and results are entered into a spread- minimum amount of waste is 4. applying the appropriate sheet for tracking purposes. generated. We also need to verify instrumentation to allow TA-55 the extent of waste reduction to properly respond to waste achieved through process opti- monitoring requirements both mization initiatives. now and in the future.

Waste Management 99 Waste Stream Monitoring (continued)

Thirteen flow meters are in To monitor the various An inductively coupled ICP-MS place at various locations outputs of the waste stream will be acquired to complement throughout the basement of system, an industrial PC-based the ICP-ES currently on site to PF-4 to monitor the solution control system has been installed aid in the monitoring of the flows generated by the various with access in the operations waste streams. The process processes. To track total gamma center. Four data concentrators control is upgraded continually activity, sodium iodide gamma capable of accepting 32 input to ensure monitoring of new detectors have been placed at channels and providing up to locations and instrumentation as various locations on the process 8 output channels are routed they are added. New level piping in the PF-4 basement. To through single communication sensors will be installed on the handle the unscheduled flow cables to the operation center. surge tank to provide more into the industrial waste line that TA-55 is implementing accurate measurements. This goes to the waste-handling appropriate instrumentation proactive approach to waste facility at TA-50, a surge tank and methods to ensure better management will demonstrate was installed in the basement monitoring of waste streams. our commitment to minimizing immediately preceding the the environmental impact of our point where this line leaves the operations while optimizing facility. plutonium recovery. +

100 Nuclear Materials Technology Division Annual Redew WASTE MANAGEMENT

Waste Treatment: Chelating Polymers for Removal of Heavy Metals from Aqueous Waste Streams by Gordon D. Jarvinen Nuclear Materials Processing Group: Nitrate Systems

A]temativetec~olo~es are The separation properties of the The exploratory work done urgently needed for the treat- polymer-supported ligands are by our R&D team has demon- ment of waste waters to reduce being evaluated to allow a strated the effectiveness of this the concentration of contaminat- complete engineering assess- approach to cleaning up waste ing metal ions to meet increas- ment of these polymer systems waters. Collaborators in this ingly stringent regulatory limits in combination with complemen- work include the Los Alamos and to decrease waste disposal tary technologies Laboratory groups INC-1,CLS-1, costs. We are developing a and to compare them with MST-7, and EM-7; Reilly Indus- series of polymer-supported, competing technologies. tries; the University of New ion-specific extraction systems These new polymer materi- Mexico; Texas Tech University; for removing actinides and other als can provide a cost-effective New Mexico State University; hazardous metal ions from waste replacement for sludge-inten- and the University of Tennessee. water streams. Our work focuses sive precipitation treatments Removal of metal ions from primarily on metal contaminants and yield effluents that meet aqueous solution is a major (especially plutonium and more stringent discharge re- industrial activity that includes americium) in waste streams quirements. At Los Alamos, we processes such as water soften- from TA-55, at the Waste Treat- are striving for a 95’70reduction ing, hydrometallurgical recovery ment Facility at TA-50, and at the of low-level sludge volume and from ores, and detoxification of Rocky Flats Plant. We are testing a 50?10reduction in transuranic waste waters and contaminated ligands to identify the com- (TRU) sludge volume at TA-50. natural waters. The concept of pounds having the required These systems could also be attaching metal-ion-specific selectivity and binding constants applied at Rocky Flats, Hanford ligands to polymers is an impor- to remove the target metal ions and other DOE facilities. tant approach to solving such from the waste streams. Selected problems and has received ligands are then incorporated considerable attention over the into poly-meric structures that past 20 years. Separations will allow ready separation of involving transition metals have the target metal ions from the dominated the work in this area. waste water stream.

Waste Management 101 Waste Treatment: Chelating Polymers for Removal of Heavy Metals from Aqueous Waste Streams (continued)

Relatively little work has In many of the waste streams to The pM value is defined as been done for the actinides and be addressed, the target metal log[Th], where [Th] is the lanthanides, with the exception ion is present in very low con- amount of free thorium remain- of a rather large body of work centration compared with metals ing in solution at any given pH dealing with the use of chelating such as sodium, potassium, starting with equal quantities of polymers to recover uranium calcium, magnesium, and iron. metal and chelator (both in from seawater. Chelating poly- solution). In this case we are mers are the basis of a number of Polyhydroxamate Chelators treating 1 ppb, a typical pluto- successful industrial separations We have evaluated several nium concentration in the including removing calcium to polyhydroxamate chelators for TA-50 waste-stream influent. part-per-billion levels from brine their ability to bind thorium The figure ih.strates the poten- and removing radioactive ce- and have obtained preliminary tial of these chelators, at near- sium from alkaIine waste waters. rewdts with plutonium. neutral pH and above, for Reducing the concentration Some results for thorium reducing the amount of pluto- of a target metal ion to the are shown in Fig. 1. nium in low-level waste streams desired level will require that Desferrioxamine-B (DFB) to levels well below 2pCi/liter the chelating polymer have a is a naturally occurring for plutonium 235. The value of binding strength that is high chelator that is commercially 2pCi/liter has appeared in at enough to accomplish the de- available, and OZ-118 is a least one EPA proposal as a sired separation. However, in new synthetic chelator pre- limit for aIpha-emitting isotopes the presence of other cations, the pared by Prof. A. Gopalan, in drinking water. These ligand wilI require a large our collaborator at New Mexico calculations indicate that upon selectivity if the target metal ion State University. attachment of these chelators to is to overcome the competition solid supports, it should be from these other cations for the possible to reduce the amount Iigand binding sites. of plutonium to extremely low levels.

102 Nuclear Materials Techndow Division Annual Retlcw Fig. 1. Calculafionsfor amount of uncompleted thorium in the presence of 18 polyhydroxamate chelatorsindicatethat thorium and plutonium can be reduced OZ-118— to very low kvels. 16

H #4

12 30 pCi/L limitfor Pu


2 4 6 8 10 12 pH

Polyhydroxamate chelators Iron is typically found in waste Gopalan’s group has also syn- such as those illustrated above waters at part-per-million levels, thesized the compound 02-184, are selective for highly charged which may be enough to saturate which has a rneta-xylenebridge metal ions such as plutonium the polymeric chelating resin in place of the propylene bridge and americium(III). Therefore, with iron. This behavior might of 02-118. The thonum(~)-and they are not likely to bind metals be expected for the chelator DFB, iron(III)-binding constants of this such as magnesium, calcium, or which has evolved in microbial compound have been measured sodium even in the presence of systems to bind iron(III) in the and show that this compound large excesses of these metals, as environment. However, the indeed binds thonum(IV) 3.5 is often the case in waste process tetrahydroxamate chelators have orders of magnitude more streams. However, they would been designed to be selective for strongly than iron(III). We normally be expected to bind plutonium over iron(HI). expect plutonium to bind iron(III) as well as or better than even more strongly to 02-184 plutonium. than thorium; therefore, 02-184 should have even larger selectivity for plutonium (IV) over iron (III).

Waste Management 103 Waste Treatment: Chelating Polymers for Removal of Heavy Metals from Aqueous Waste Streams (continued)

Bis(acylpyrazolones) with High The extraction system was also We have attached some of these Selectivity for Tetravalent highly selective for plutonium compounds to poIymers such as Actinides over thorium. The high polybenzimidazole through the The l,3-diketones have been selectivity for tetravalent R“ group on the methylene extensively studied as extractants actinides over iron(III) results carbon. The extraction properties for actinide and lanthanide ions. from the very slow kinetics of of these chelating polymers is The linking of multiple 1,3- iron extraction. The selectivity under investigation. diketone units to give compounds of these compounds has potential . A A with increased bi~ding constants uses in novel sensors and separa- SYnthetic Methods for Prepara- for divalent metal ions, uranium tions, and a patent applicati~n t~onof Chelating Polymers (VI), and some Ianthanide ions has been filed. The major synthetic methods has been reported. However, Because these systems have used in the preparation of chelat- data on metal complexation for demonstrated an enhanced ing polymers are such compounds are rather selectivity and high binding 1. polymerization of limited. In a systematic study constants for tetravalent actinides, functionalized monomers, seeking to enhance actinide ion they will be evaluated for 2. polymerization of binding by preorganization, we removing plutonium from nonfunctionalized have synthesized a series of the waste streams. At pH >2, monomers followed by acylpyrazolone ligands linked they will also be evaluated for chemical modification, with four to eight methylene removing americium(lTI). 3. graft polymerization of a units (see Fig. 2) and have functionalized monomer investigated their complexation Malonamides on a prepared polymer, chemistry. A liquid-liquid extraction and A large increase in selectivity process proposed by French 4. physical entrapment of (>103)for plutonium and workers for removing trivalent hydrophobic chelating thorium over uranium, actinides from PUREX waste extractants during poly americium(III), europium(III), streams based on malonamides, merization or iron(III), and aluminum(III) was RR’NC(0) CH(R’’)C(O)NRR’, postpolymerization. found relative to closely related has potential advantages over bidentate compounds. the TRUEX process.

104 NucIcar Materials Technology Division Annual Revkw Fig.2. Bis(acylpyrazolones) have a high selectivityfortetravalentactinicles. ‘hw’-w,.

We have used all of these routes Our approach is to improve the Copolymerization with other in our exploratory studies. Most performance of the polymer monomers can incorporate other of our polymer extractants will beads by designing several new features. Hydrophilic groups be prepared by attachment of features into the polymer struc- can be incorporated into the ligands to a prepared polymer, ture. The surface area will be grafted chains so they will such as polybenzimidazole. increased by graft polymeriza- extend freely into the aqueous However, we feel the graft tion of chelating groups onto the medium. The kinetics of binding polymerization route will yield surface. This arrangement differs will be enhanced by these chains, chelating polymers with some from that of standard chelating which are essentially water greatly improved properties. polymers in that a long chain of soluble but bound to a polymer These materials will be chelating groups will extend base. Other factors can be discussed in more detail below. away from the surface rather designed into the graft polymer than be fixed into the rigid such as spacer groups to opti- Advanced Chelating Polymers interior of the resin. mize chelation. We have an approach that The flexibility of the long The ultimate in selectivity of will advance chelating polymers chains will have several benefits complexation can be achieved by beyond current technology. over fixed sites. Frequently two use of a ligand preorganized for Chelating polymers are cross- or more chelating sites are a specific metal ion at each Iinked, insoluble, porous required to bind a metal. In rigid functionalized site in the grafted polymer beads with functional polymers, many sites may be polymer chain. For example, chelating groups. They have unable to chelate because nearby this ligand could be one of the high surface areas and exchange Iigands are not oriented properly tetrahydroxamates discussed capacities that range from less to allow chelation and many over or a crown ether with acidic than 0.1 to about 10 meq/g. sites are unavailable. Long, arms developed to encapsulate a flexible chains of Iigands will particular ion. In this case, make many more sites available. cooperation between binding sites located at different points along the chain or on different chains would not be required. +

Waste Management 105 106 Nuclear Materials Technology Divldon Annual Re\lew






1(X3 Nuclear Materials TIAUIOIOWDivision Anmml Review NMT-DO NUCLEAR M ATE R IALS TECH N O LO GY

DIVISION I --== \\

~, , _.,,, .—. L—l . I I IK Division Leader Deputy Division Leader Delbert R. Harbur Da~a C. Christensen

Nuclear Materials Technol- The Division Office manage- Approximately 5 percent of our ogy Division conducts scientific ment team works directly under people are postdoctoral appoin- and technical work within the the division leader and deputy tees, graduate research assis- nine operating groups shown in division leader to provide pro- tants, or undergraduate summer the organizational chart. The title grammatic and administrative students. The remainder of our of each group indicates the support to the division’s staff employees provide very neces- group’s major functions or re- and management. One of the sary administrative and nontech- sponsibilities. However, most team’s most important tasks is to nical management and support of our groups carry out a variety maintain effective communicat- functions for the division. of efforts to support our national ion between NMT Division and Materials science has a defense and energy programs, other Laboratory divisions, multidisciplinary focus that re- and most groups conduct active Laboratory program offices, and quires insight and support from research programs to support upper management. The man- many different professional dis- their main technological or pro- agement team also works closely ciplines. Included among our grammatic emphasis. Our oper- with funding agencies and other staff are chemists, metallurgists, ating groups range in size from external organizations. The real physicists, mathematicians, ce- approximately 20 to nearly 70 strength of NMT Division is our rarnists, and engineers with employees. people. At present, NMT Divi- many specialities. Almost all of The NMT Division Office, sion employs approximately 500 our staff members have scientific along with group managers, people, including part-time and or engineering degrees; 72 per- provides technical leadership, temporary employees. More cent have either a Ph.D. or M.S. managerial guidance, and ad- than 87 percent of the division’s in their respective specialties. ministrative support to the employees are staff members or Our technicians also represent division’s operating groups. technicians, the vast majority of a wide range of disciplinary in- The Division Office is also a focal whom are working on scientific terests, including mechanical, point for nuclear materials issues or technical activities. chemical, and materials within the Laboratory. Along technology. with materials and chemistry staff elsewhere in the Laboratory, the NMT Division Office pro- vides overall direction and lead- ership to the Laboratory’s materials and chemistry efforts.

Group Profik 109 NMT-1


Our group has 28 employees: 7 staff members, 13 technicians, 1 support per- son, 5 consultants, I graduate research Group Leader assistant, and 1 postdoctorate Kenneth Chidester researcher. 1 Iu Deputy Group Leader Walter A. Stark

The Nuclear Fuels Technol- Our nuclear-fuels-develop- The Fuel Research Section studies ogy Group, NMT-1, specializes ment laboratories support a high-temperature performance of in research, development, irra- wide range of R&D activities, various fuel/cladding combina- diation testing, and fabrication including phase transformations tions. Knowledge of high-tem- of uranium- and plutonium- and diagrams, high-temperature perature interactions is essential based fuels. Our group diffusion studies; fueI/liner/ to choices of new ceramic-fuel/ backs up the disciplines of cladding/coolant capability refractory-alloy combinations for chemicaI synthesis, ceramic measurements, kinetics of high- use at high temperatures and/or fabrication, and metallurgy temperature interactions, devel- high burnups. We are currently with expertise in materials char- opment of novel synthesis and developing and characterizing acterization, analytical chemis- fabrication methods, refractory high-melting-point carbide com- try, nondestructive examination, alloy weld development, irradia- pounds for nuclear propulsion and quality assurance. We ini- tion testing, and postirradiation reactors. Before commitments tiate high-risk/high-payoff re- analysis of fission products can be made to reactor designs search and development for migration, fission gas release, that call for various fuel types, national advanced reactor pro- swelling, and thermochemical fuel cladding combinations must grams. An example is the devel- interactions. be tested. We test ex-pile compat- opment and fabrication of Our group has four sections: ibility and in-reactor performance high-quality pelleted uranium Fuel Research, Fuel Develop- on such combinations as nio- nitride for the SP-1OOspace ment, Fuel-Pin Assembly, and bium, rhenium, and tungsten power reactor. We develop ad- Materials Characterization. with uranium nitride and ura- vanced fuel and cladding fabri- nium carbide. cation techniques, measure fundamental properties, build fuel pins for irradiation testing, analyze performance, and dem- onstrate fabrication procedures. Our ultimate goal is to turn over demonstrated fuel technologies to private industry for potential commercial development.

110 Nuclear Materials Technology Oivls[on Annual Review “The Nuclear Fuels Technology Group, NMT-1, specializes in research, development, irradiation testing, and fabricatiorzof uranium- and plutonium-based ceramic fuels.”

Fuel-development activities Thirty-five atmosphere-con- Our Materials Characteriza- include researching advanced trolled gloveboxes, powder- tion Section examines fuel and processes and fabricating fuel preparation equipment, four cladding components for ad- for terrestrial- and space-based automatic pellet presses, three vanced fuels and heat-source reactor concepts. NMT-1 has large-capacity synthesis fur- programs, as well as plutonium developed and supplied pelleted naces, and three large-capacity metal and alloy samples for uranium nitride fuel for the sintering furnaces are available weapons programs. This section SP-1OOspace reactor and for production. A small-scale also provides general photo- uranium carbide for the 1iquid- fabrication line is also available graphic support to other NMT metal fast breeder reactor. We for developing novel fabrication groups. Capabilities include are currently developing a techniques. ceramography, metallography, cryochemical process to fabricate Our Fuel-Pin Assembly x-ray diffraction, residual gas spherical fuels for space propul- Section develops and qualifies analysis, surface area analysis, sion reactors. We synthesize refractory alloy welds, anneals and image analysis. + oxide feedstocks to carbide or cladding components, and fabri- nitride powders by carbothermic cates fuel pins for irradiation reduction at up to 15 kg per week. testing of pin-type reactor con- We can fabricate up to 15 kg per cepts. Up to 60 full-length fuel week of nitride or carbide fuel pins per week can be loaded pellets or 30 kg per week of oxide with fuel pellets, welded, fuel pellets by conventional cold cleaned, annealed, wire- pressing and sintering. wrapped, examined, and pack- aged for shipment. Fabrication techniques include vacuum- annealing, electron-beam and gas-tungsten arc welding, profilometry, eddy current testing, gamma scanning, and x-radiography.

Group Profiles 111


NMT-2 has 73 empIoyees:22staff members,1 limited-termstaffmember, 37 technicians,4 supportpersonnel, DeputyGroupLeader 1 databasemanager,6 Laboratory BillJ. McKerley associates,1 Laboratoryconsultant, GroupLeader and1postdoctoralresearcher. LarryR Austin

The Nuclear Materials Third, we support the Los Our primary process flow sheet Processing Group (Nitrate Alamos Plutonium Facility by consists of nitric acid/hydroflu- Systems), NMT-2, develops recovering and purifying pluto- oric acid dissolution or leaching and demonstrates processing nium from scrap residues and followed by purification with technology for plutonium and producing a pure metal that can anion exchange. The plutonium other actinides by primarily be used for weapons fabrication in the concentrated ion exchange using aqueous-based operations. development activities. The ma- eluate is precipitated with oxalic Our mission has three major jor goals of these efforts are to acid, then filtered, dried, and components; First, we support improve process safety and effi- thermally decomposed to form the Department of Energy (DOE) ciency, including minimization plutonium oxide. The plutonium complex by developing new and of all wastes leaving our facility. oxide may then be converted to a improved methods for pluto- We possess the facilities and tetrafluoride by reaction with I-IF nium recovery that are safe, effi- expertise to demonstrate on a and reduced to metal by calcium cient, and environmentally production scale the recovery in a high-temperature reduction sound. Second, we demonstrate and purification of plutonium furnace. new operations on a sufficiently from a wide range of contami- Our group’s research, devel- large scale to make them attrac- nants and scrap matrices. Our opment, and demonstration ef- tive to the plutonium facilities of feed materials also consist of forts directly support all major the future, thus improving fu- residues generated at off-site processing operations at TA-55. ture overall operational effec- facilities. Frequently, these tiveness and efficiency. facilities do not have the special- ized capabilities to handle the more exotic contaminants, and consequently we provide this service for the DOE complex.

112 Nuclear Matt.riak Technology Divis[on Annual Review “The Nuclear Materials Processing Group (Nitrate Systems), NMT-2, develops and demonstrates processing technology for plutonium and other actinides by primarily using aqueous-based opera tions. ”

We continue to improve our In the area of waste minimi- The ATLAS uses a distributed understanding of the underlying zation, we are developing selec- process-control scheme based on chemistry of all the processes, tive extraction systems to reduce a PC network running a process- which enables us to improve radionuclides in aqueous waste control software package, and operations. Our process-devel- streams to very low levels. In ad- analytical support provides near opment activities are concen- dition, we are evaluating oppor- real-time results for both the ac- trated in four major areas: tunities to recycle many of our tinide and impurity content of reagents, such as nitric acid, to the various streams that are used 1) process chemistry, also reduce the waste streams to optimize process efficiency. 2) process analytical chemistry, leaving TA-55. All of these tech- Integrating all of the major 3) process monitoring and nologies arebeing developed and aqueous unit operations, along control, and tested in the Advanced Testing with the process control and the 4) process engineering. Line for Actinide Separations analytical support, is a first for (ATLAS). This integrated pilot the industry. It will be used to Scientists in these major areas plant operation, housed in six optimize process efficiency for focus on specific projects. For interconnected gloveboxes, minimizing waste generation. example, a sensor for high-acid encompasses all the major unit Progress in these areas results in concentrations was developed operations currently used for purer product, decreased waste by our personnel and was the nitrate aqueous processing generation, and lower personnel selected as one of the top 100 of actinide scrap. These include radiation exposure. These activi- developments of the year, dissolution, anion exchange, ties have far-reaching potential earning an RD1OOaward. precipitations (oxalate, peroxide, for aiding modernization and and hydroxide), calcination, and environmental cleanup efforts evaporation for waste treatment. within the DOE complex and in industry. +

Group Profiles 113 NMT-3

N U C L t ~ 1< MATE R IA LS P R O C E SS I N G:

CHLORIDE SYSTEMS &i azI Ourgroup has 52 employees:17 technical Group Leader staff:members,30technicians,1support ,-loel—.—.D. Williams I person,2 postdoctoralresearchers~~d DeputyGroupLeader 2 Labassociates. S. MarkDinehart

For the most part, the Within the group, the scrap Long-range plans in the NucIear Materials Processing recovery activities center around area of aqueous recovery Group, NMT-3, (Chloride the use of hydrochloric acid include at-line analytical capa- Systems), supports the residue media as the basis for process bilities. One such technique, elimination program at the chemistry. Dissolution of scrap gas chromatography, is already Rocky Flats plant and process matrices, including actinide being evaluated as support for development and demonstration metal, results in a solution that the solvent-extraction process. for Complex 21. However, we is processed through either Recent changes to this process also have an important role in solvent extraction or chloride have necessitated sampling and the weapons program at the Lab. ion exchange. The solution assay analysis of the organic stream to Within the group, we are de- is the determining factor; rich assure proper composition. Gas veloping an integrated approach soIutions go through solvent chromatography, a technique to chloride-based processing extraction for purification, and used widely in industry, pro- technologies. This encompasses lean solutions go through ion vides an at-line analysis that both the aqueous systems and exchange. A new set of corro- will help assure optimal process the high-temperature, molten sion-resistant, Kynar-lined performance. salt systems. New equipment, gloveboxes have been installed Improved diagnostic and new reagents, and advanced to contain the solvent-extraction monitoring techniques have process diagnostics are all being equipment. Development work also been incorporated into the incorporated into this integrated of the new dodecane/decanol/ pyrochemical operations. The approach. We have also broad- tributyphosphate-extraction sys- use of a spectrophotorneter to ened the emphasis of our weap- tem is well underway. These sol- monitor chlorine in the off-gas ons program support activities vent extraction glove boxes will from the multicycle direct-oxide to incIude demonstration of new begin processing scrap from the reduction process is an excellent equipment and technologies for TA-55 vault in late FY92. Further exampIe. Enhanced diagnostic removal of low levels of actin- upgrades to the aqueous chlo- techniques, such as the use of a ides from process streams. ride processing line include new, high-temperature reference corrosion-resistant boxes to electrode in electrorefining, are house the ion-exchange process also being explored. and, eventually, a set of gloveboxes for off-gas scrubbing and other process/facility inter- face support.

114 Nuclear Matcrids Technology Di\isionAmud Rmicw “For the most part, the Nuclear Materials Processing Group, NMT-3, (Chloride Systems), supports the residue elimination program at the Rocky Flats plant and process development and demonstration for Complex 21. However, we also have an im- portant role in the weapons program at the Lab.”

Process optimization, through Specific goals of this work in- This change is a natural out- improved monitoring capabili- clude the definition of the rela- growth of our efforts in the ties, is one of the benefits we ex- tionship between gas flow rates areas of waste minimization pect this work to facilitate. and the production of the pluto- and programmatic support of Process development in the nium trichloride, and the subse- the WRD&T activities within area of pyrochemistry includes quent americium extraction. the Lab. The recovery capabili- not only equipment improve- During the past 3 years, Savan- ties required to support the ments but also the definition of nah River person-nel performed weapons program provide an process parameters. One ex- foundation experiments for this excellent test bed for demon- ample is the in situ chlorination work at Los Alamos. strating new techniques for the work in the molten-salt extrac- Finally, we are expanding removal of the very low-level tion process. This uses pluto- the emphasis of our direct weap- actinides present. Although we nium trichloride as the oxidant ons program support to include have just implemented this to extract decay-product ameri- the incorporation of the latest change in direction, we believe cium from plutonium metal. recovery technologies for deal- the work in this area will point Rather than adding the oxidant ing with low levels of actinides. the way to the future for as a separate reagent, we are Complex 21. + evaluating the use of gaseous chlorine sparged through the molten metal to generate the plu- tonium trichloride.

Group Profiles 115 NMT-4 N U CLEAR I t M ATE R IALS I MEASURE M E NT & ACCOUNTABILITY ; ~z Group Leader Ourgrouphas35employees:12staff Raymond P. Wagner members,21 technicians,and2 support DeputyGroupLeader personnel. DennisL. Brandt

N’uclear Materials Mea- Our nuclear materials control We operate two neutron surement and Accountability, activities include coordinating counters, five gamma-ray assay NMT-4, is a service group that and acting as the focal point for counters, five gamma-ray isoto- uses nondestructive assay internal and DOE audits, origi- pic counters, and seven calorim- methods to measure nuclear nating and maintaining process- eters. Our Instrumentation materials at the TA-55 Pluto- accountability flow diagrams, Section maintains and calibrates nium Facility. Our group also investigating and resolving in- these instruments, as well as the helps TA-55 comply with Los ventory differences, interacting accountability instruments used Alamos and regulatory agency with the Laboratory’s Program in the process lines. policies regarding nuclear mate- Director for Safeguards Assur- We are installing and operat- rials accountability. Successful ance, and verifying that TA-55 ing robotic and automated sys- accountability of nuclear materi- personnel are trained to use tems to increase our throughput als results in quality process material surveillance procedures. of assayed materials, as well as controls, increased production, Our group is responsible for de- to enhance safety and security. timely availability of nuclear termining and investigating any A full-scale automated assay sys- materials, and increased safety shipper/receiver differences. tem (robotic calorimeter, and safeguards. Nondestructive assays are es- RbobCal) is being used to assay Specifically, we provide sential to any safeguards pro- process materials. An automated services in nuclear materials gram. They confirm and verify low-level solid waste handling control and accountability, the presence and stated quanti- and measuring system is being nondestructive assay, and ties of nuclear materials. We also built. + measurement control. use NDA measurements in isoto- pic blending operations.

116 Nuclear M.mmialsTechnology Civision Annual Review NMT-5 PLUTONIUM M ETA LLU RGY

.,. Ourgrouphas54employees:19staff . . - members,31technicians,2 officesup- 1 III port,2 graduateresearchassistants,”and GroupLeader DeputyGroupLeader 2 Laboratoryassociates. MichaelF. Stevens RuebenL. Gutierrez

The plutonium Metallurgy Our Fabrication Section con- In addition to pit fabrication Group, NMT-5, is a multi- structs the prototype pits that are capabilities, the fabrication disciplinary organization en- primarily used in Nevada Test section maintains a unique gaged in prototype weapon pri- Site research. We use modern facility for manufacturing mary fabrication, metallurgical casting, machining, and assem- isotope detector packages, used and chemical properties studies bly technology to provide in postshot diagnostic studies. of plutonium and other actin- war-reserve-type plutonium This facility features a robot-op- ides, and surveillance and stock- components in support of this erated, isotope-powder filling pile evaluation technologies in highly important Laboratory station, unique within the DOE support of Laboratory and the activity. We are constantly weapons complex. Besides accu- Department of Energy (DOE) upgrading and expanding our rately manufacturing these weapons programs. Our group capabilities in fabrication, as detectors, our studies of radia- is principally supported through exemplified by our installations tion-exposure reduction to work- the Laboratory’s weapons re- of advanced vacuum-induction ers resulting from the use of this search, development, and testing casting and Nd:YAG laser-weld- robot wiLlserve as a pilot study programs, although significant - ing (1-kW, pulsed) systems. for the appropriate use of other technology support and devel- Our flexibility in metal process- such automated stations in the opment efforts are funded ing and fabrication serve as an complex of the future. through production and surveil- excellent proving ground for de- The Process Research and lance and environmental restora- velopment of modern complex, Development Section continues tion sources from within DOE. or Complex-21, methodologies. to expand its role in weapons A major new functional respon- safety, surety, and reliability sibility for the Plutonium Metal- research. We are completing lurgy Group will be to perform installation of a comprehensive pit evaluation studies on stock- furnace system for simulated pile return pits. accidental fire testing of nuclear primaries in vacuum, inert gas, and oxidizing atmospheres.

Group Profiles 117 “The Plutonium Metallurgy Group, NMT-5, is a multi-disci- plinory organization engnged in profofype weapon primary fab- rication, metallurgical and chemical properties studies of plufoniwn and ofher acfinides, and surveillance and stockpile evaluation technologies in supporf of Laboratory and the De- parfnlenf of Energy (DOE) weapons programs.”

In the meantime, we continue to Our Actinides Chemistry To complement this work, we conduct fire-resistance tests for and Physics Section continues have adapted our capabilities in engineering qualification of not world-recognized work ranging Fourier transform infrared spec- only Los Alamos system designs, from fundamental surface chem- troscopy (lTIR) to quantify the but also designs from the United istry to solid-state physics re- presence of contaminants on Kingdom, with whom we share search on the actinides. We have plutonium and other metal sur- other nuclear safety technology. extended our findings on the faces. In addition, we continue In a simiIar vein, we will also be nature of radio-frequency fundamental studies into the conducting safety verification plasmas to develop unique mechanisms of surface chemical tests in support of Lawrence methods for removing trace reactions and the electronic Livermore National Laboratory quantities of actinides from the structure of plutonium, the systems presently in the stock- surface of various substrates, actinides, and their compounds. pile. Our materials scientists are providing a decontamination We are also responsible for also conducting various experi- method that produces little or no the successful installation and ments in order to elucidate the waste stream. The push to elimi- operation of the 40-mm gas/ consequences of aging on the nate chlorofluorocarbons (CFCS) powder launcher at the Pluto- properties of pIutonium and to in manufacturing has led us to nium Facility. The launcher will extend these findings to support study the use of supercritical offer DOE researchers a unique weapon-reuse studies. carbon dioxide as a solvent for opportunity to investigate ilzsitu residue surface oils on pluto- dynamics mechanical properties nium, as well as preliminary of plutonium. Data from such studies into the use of aqueous testing will enable weapon cleaning agents, such as deter- design codes to more accurately gents and other surfactants, to predict performance. + remove residues.

118 Nuclear Materials Technology Division Annual Ret’iew NMT-6 ACT I N I D E MATE R IALS I — --—-— C H E M ISTRY

Our group has 24 employees: 14 techni- cal staff members, 8 technicians, 1 office support person, and 1 graduate re- search assistant. Inorderto accomplish ourgroup’smultidisciplinarymission, ml I la ourscientificstaff’sexpertiseranges GroupLeader DeputyGroupLeader broadlyin inorganicandphysicalchem- KyuC. Kim ThomasW. Blum istry,materialsscience,andchemical engineering.

The Actinide Materials Our group focuses on new and Chemistry Group, NMT-6, con- emerging technologies and on ducts fundamental and applied improving existing technologies research in actinide chemistry to with strong emphasis on waste develop and maintain diverse reduction, safety, environmental scientific expertise and capabili- improvement, and efficiency. ties and to apply the technology Our group has established base in support of nuclear mate- broad collaborations with other rials proc~s~ingand process de- groups, implemented new and velopment activities in Nuclear improved recovery and purific- Materials Technology (NMT) ationprocess concepts and ad- Division. vanced diagnostic techniques, Technical and scientific tasks and applied our research exper- are distributed between the Pro- tise, especially in spectroscopy cess Chemistry and Advanced and thermodynamics. In addi- Separation Concepts sections. tion, we are active in technology Main activities include organo- transfer and consultation with actinide chemistry, plutonium other nuclear materials produc- chlorination and fluorination, tion sites and other national plutonium thermochemical stud- laboratories. + ies, process control and diagnos- tic development, actinide spectroscopy, waste gas treat- ment, and chemical and physical plutonium separation and purifi- cation technology development.

Group Profiles 119 NMT-7


Ourgrouphas39employees:10staff =~ DeputyGroupLeader members,28technicians,and1support GroupLeader CharlesL. Foxx person. CarolL.Sohn

Nuclear Materials Manage- We manage the secured vault Our coordination of nuclear ment, NMT-7, manages the in which nuclear materiaIs not in materiaIs includes diverse activi- movement of nuclear materials process are stored. This opera- ties in support of programmatic within the TA-55 boundaries. tion includes safely introducing requirements. We have devel- Group programs include waste and removing material and oped a site-wide nuclear materi- management, nuclear materials maintaining the required docu- als model that forecasts future storage, roasting/blending, ship- mentation. In addition, we inventories of scrap and waste ping/receiving of nuclear mate- blend, sample, roast, and con- generation and that examines rials, and coordination of nuclear solidate various feed materials the impacts of new technologies materials. for metal preparation and aque- on the TA-55 Plutonium Facility. Waste management is one of ous recovery. In support of the model, we have our most important functions at We also coordinate the ship- created a waste generation data NMT-7. Our handling of liquid ping and receiving of nuclear base that provides detailed infor- waste ensures that acidic and materials, including packing and mation about waste origins. We caustic waste solutions meet the unpacking shipments in compli- are initiating electronic transmis- applicable discard limits and are ance with the current Depart- sion and generation of the volu- suitable for processing by the ment of Energy regulations. We minous records associated with Laboratory’s central waste treat- routinely ship and receive prod- our operations. + ment plant. Our solid waste ac- uct and process feed materials, tivities involve cement fixation scrap, analytical samples, and of the treated liquid wastes that waste. meet pertinent discard limits. In addition, we develop the proce- dures to meet Waste IsoIation Pilot Project certification requirements for solid waste.

120 Nuclear Materials Tcclmology DivlslunAmual RLW%?W NMT-8 TA-55 FACILITIES MANAGE M E NT

/ L. I

Ourgrouphas51employees:11staff L, ! DeputyGroupLeader members,15technicians,19support GroupLeader RichardA. Brie.smeister personnel,and6 casualemployees. DavidJ. Post

The TA-55 Facilities Man- Our site administration re- agement Group, NMT-8, over- sponsibilities include warehouse sees all engineering operations operations, safety operations, and maintenance at the TA-55 change rooms, access control, plant and manages the engineer- telecommunications, computer ing design and construction of systems, equipment inspections, new facilities and renovations of and financial management. We existing facilities. also communicate on behalf of NMT Division with the Opera- tional Security and Safeguards Division and the Laboratory’s protective force. +

Group Profiles 121 NMT-9 HEAT SOURCE l— I TECH N O LOGY

GroupLeader Ourgrouphas38 employees,9 staff RoyWayneZocher members, 22 technicians,4 support personnel,and3 casualemployees.

The Heat Source Technol- Processing of Plutonium 238, These heat sources will ther- ogy Group, NMT-9, has long- which began at Los Alamos in mally stabilize scientific equip- term experience with the late 1950s, has expanded to ment and critical valves during radioisotope heat-source devel- include the missions. opment for terrestrial and space 1. design of radioisotope Our group evaluates the e~ectricalgenerators. Heat - heat sources, high-temperature and impact re- sources developed at Los 2. development of fuel sponse of candidate heat-source Alamos have been used on ra- fabrication processes, materials, incIuding graphite dioisotope thermoelectric gen- 3. fabrication of a variety composites, noble metal alloys, erators (RTGs) to supply of heat-source fuel forms, fuel simulant, and alternative in- electrical power for NASA 4. safety tests and postmor- sulating materials. We are also spacecraft, including the Pioneer tem examinations of investigating methods to decon- 10 and 11, Voyager 1 and 2, tested heat sources, taminate and return the Galileo, and Ulysses deep-space 5. safety assessments of material to the national stock- exploration missions. Some of radioisotope power pile. the spacecraft also required generators, and Our group recently ceased small radioisotope heaters, de- 6. heat-source materials fabrication of mW-generator veloped and produced at Los research, development, (MWG) heat sources that are Alarnos, for thermal input to and service evaluation used in RTGs for weapon com- critical components. for space and terrestrial ponents, but we will continue to applications. perform stockpiIe surveillance Our group is supporting the on these heat sources. We are upcoming Cassini mission by currently transferring the mW 1. requalifying the general- stockpile surveillance and stor- purpose, heat-source age characteristics activities at (GPHS) fuel-fabrication General Electric Pinellas Plant to process, Los Alamos, + 2. performing independent safety assessments on the components and RTGs to be used, and 3. fabricating lightweight, radioisotope heater units.

122 Nuclear Materials Technology Division Annual Rmicw A WAR DS




Duringthe year,NMTDivision’speopleachievedmanynotable scientificand technicalaccomplishmentsandreceivedawards recognizingtheirefforts.Someof our employeeswhowererecognized fordistinguishedcontributionsin scientificor technicalareasarelisted here.The individualswithinNMTDivisionwhowereawardedpatents duringthe yearare listedalso.Here,too,we applaudtheseindividuals fortheircontributionsin areasthathavehigh potentialto benefitnot onlythe Laboratorybut ournation.

H. L..Nekimken (NMT-2), FY 1991 R&D 100 Award for development of the “Optical High-Acidity Sensor,” (issued September 1991).

H. L. Nekirnken (NMT-2), Federal Laboratory Consortium Award for Excellence in Technology Transfer for 1992 (issued February 1992).

H. L. A?ekimken(NMT-2), “Optical High Acidity Sensor,” S-72,805, S.N. 07/770,388 (patent application filed October 3, 1991).

Q. Fernando, N. Yanagihara, J. T. Dyke,K. Vemulapalli, (NMT-2), “Forn~ationof Rare Earth Carbonates Using Supercritical Carbon Diox- ide,” U.S. Patent 5,045,289 (issued September 3, 1991).

S. F. Fredric Marsh (NMT-2), Member of the DOE Red Team (Phenom- enology Subteam) assigned to provide an independent assessment of WHC plans and strategy for the Hanford Tank Waste Project to Leo Duffy, DOE Headquarters.

S. F. FredricMarsh (NMT-2), Member of DOE delegation sent to France, August 26-30, 1991, to evaluate French technology that might be applicable to the Hanford Site Restoration Project, at the request of John Tseng, DOE Headquarters.

124 Nuclear MakiakT&mology Divklon Annual Ibxiew S. F. FredricMarsh (NMT-2), Invited presenter of “The Effects of Exter- nal Gamma Radiation and ZrzSituAlpha Particles on Five Strong-Base An- ion Exchange Resins,” at the 1987 Godon Research Conference on Reactive Polymers, Ion Exchangers, and Adsorbants, Newport, Rhode Island, Au- gust 19-23,1991.

S. F. Fredric A&rsh (NMT-2), One of three invited Los Alamos partici- pants to the Fint Hanford Separations Science Workshop, Richland, Wash- ington, July 23-25, 1991.

S. L..Yarbro (NMT-2) ATW Chemistry Team Leader, Accelerator Trans- mutation of Waste Program.

Heat Source Technology Group (NMT-9), 1991, National Aeronautics and Space Administration, Group Achievement Award for Galileo Safety for Contributions to Design, Analysis, Testing, and Documentation required to ensure safe use of radioisotopic thermoelectric generators and radioisotope heater units for the Galileo Ulysses missions.

R. W.Zocher (NMT-9), Certificate of Recognition for Achievements in “Nuclear Fuel Elements,” US Patent No. 5,002,723 (issued March 26, 1991).

Awards, Honors, Patenb 125 126 Nuclear Materials Technology DivMon Annual Review P U B LI CAT I O N S

127 P U B LI CAT I O N S

Another important component of our scientific and technical effort is the communication of results and conclusions to our sponsors and the scientific community at large. During the past year, our staff published many scientific papers and reports (listed on the following pages). Documents of unlimited distri- bution cannot cite classified or limited access publications. For this reason, this is not a complete listing of NMT-Division publications.

Nuclear Fuels Technology (NMT-1)

In the following publications list, the single underline identifies the author as a group member. If you would like to contact any of these authors, please write to them in care of the Nuclear Fuels Technology Group, Mail Stop E505, Los Alamos National Laboratory, Los Alamos, New Mexico 87545.

1. “Advancing Liquid Metal Reactor Technology with Nitride FueIs:’ R. B. Baker, R. D. Legget, W. F. Lyon, R. B. Matthews, InternationalFast Re- nctors and Related Fuel Cycles, Los AIamos National Laboratory document LA-UR-90-4343 (December 1990).

2. “Reactor Fuel Production in Western Europe;’ R. B. Matthews, H. T. Blair, K. M. Chidester, SAIC Study of Western European Reactor Capa- bilities, Los Alamos National Laboratory document LA-UR-91-0481 (Febru- ary 1991).

3. “Ceramic Fuel Development For Space Reactors,” R. B. Matthews, Cenun.Bull. 71,96 (January 1992).

4. “Experimental Investigation of Uranium Dicarbide Densification and The Influence of Free Carbon Diffusion,” K. M. Chidester, Thesis, Los AIamos National Laboratory document LA-11954-T (April 1991).

5. “Review of Experimental Observations About the Cold Fusion Effect,” E. K. Storma Fusion TechrzoL20,433 (December 1991).

6. “Carbide Fuels For Nuclear Thermal Propulsionl’ R. B. Matthews, H. T. Blair, K. M. Chidester, K. V. Davidson, W. A. Stark Jr., E. K. Storms, Proc. AIAA/NASA/OAl/Advanced SEI Technologies, Los Alamos National Laboratory document LA-UR-91-2317 (July 1991).

7. “Effect of Fuel Geometry on the Lifetime-Temperature Perfor- mance of Advanced NucIear Propulsion Reactors,” E. K. Storms, D. L. Hanson, W. L. Kirk, P. Goldman, Proc. AMA/NASA/OAI/Advmzced SE] Technologies, Los AIamos National Laboratory document LA-UR-91- 2428 @IIY 1991).

128 Nuclear MatwialsTcchnoIogy Oivision Annual Review 8. “SP-1OOSeptember Quarterly Report;’ C. W. Hoth, N. A. Rink, Jet Propulsion Laboratory, Los Alamos National Laboratory document LA-I-JR-91-3199(October 1991).

9. “Behavior of ZRC 1-X and UYZR 1-Y Cl-X in Flowing Hydrogen at Very High Temperatures,” E. K. Storms, Los Alamos National Labora- tory document LA-12043-MS (January 1992).

10. “Relationship Between Surface Curvature and Local Active-To- Passive Transitions During Oxidation,” D. P. Butt, Proc. Am. Cerarn. Soc., Los Alamos National Laboratory document LA-UR-92-0307 (January1992).

11. “Directional Zone Sintering In UCZCompacts,” K. M. Chidester, Proc. of the Am. Cerarn. Society, Los Alamos National Laboratory document LA-UR-92-0111 (January 1992).

12. “Diffusion of Carbon Through The Niobium Carbides (Niobium Carbide and Diniobium Carbide),” R. W. Schmude, T. C. Wallace, Nuclear Materials, pending, Los Alamos National Laboratory document LA-UR-92- 0016 (January 1992).

Nuclear Materials Processing: Nitrate Systems (NMT-2)

In the following publication list, the single underline identifies the author as a group member. If you would like to contact any of these authors, please write to them in care of the Nuclear Materials Processing: Nitrate Systems Group, Mail Stop E501, Los Alamos National Laboratory, Los Alamos, New Mexico 87545.

1. “Evaluation of Different Solvent Extraction Methods for Removing Actinides From High Acid Waste Streams,” S. L. Yarbro, S. B. Schreiber, S. L. Dunn, and J. D. Rogers, Los Alamos National Laboratory document LA-I-JR-91-3253(1991).

2. “Homogeneous Precipitations for Separations and Waste Treat- ment,” S. L. Yarbro, S. B. Schreiber, and S. L. Dunn, Los Alamos National Laboratory document LA-UR-91-2409 (1991).

3. “Los Alamos Technology Office Assessment of the Rocky Flats Plant Criticality Alarm System,” D. Smith, S. Vessard, R. E. Malenfant, and A. F. Muscatello, Los Alamos National Laboratory document LA-UR- 91-1118 (1991).

Publications 129 P U B LI CAT I O N S

4. “Optical High Acidity Sensor,” B. Jorgensen and H. Nekimken, 1992 ResearchFIigldighfs (1992).

5. “Report on Indicators for Optical High-Acidity Sensor,” B.Jorgensen, H. Nekimken, and D. Sellon, internal NMT Division report (1991).

6. “Separation Studies of Yttrium(III) and Lanthanide(III) Ions with 4-Benzoyl-2,4-dillydro-5-methyl-2-phenyl-3H-ppazol-3-tMon and TrioctylphosphineOxideUsinga RoboticExtractionSystem:’W Nekimken, B. F.Smith,G. D. larvinen,C.S.Bartholdi,revisionsubmitted to Solwwf Exfr. Ion Exck,(January1992).

7. “Synthesis of Lanthanide Carbonate Using Supercritical Carbon Dioxide,” Q. Fernando, N. Yanagihara, J. T. Dvke. J. Less-CovvnonMet. 167 (1991).

8. “Advanced Testing Line for Actinide Separations (ATLAS),” S. L. Yarbro, S. B. Schreiber, N. G. Pope, R. Dav, 1992 Resem’chHighlights (1992).

Nuclear Materials Processing: Chloride Systems (NMT-3)

In the following publication list, the single underline identifies the author as a group member. If you would like to contact any of these authors, please write to them in care of the Nuclear Materials Processing: Chloride Systems Group, Mail Stop E511, Los Alamos National Laboratory, Los Alamos, New Mexico 87545

1. “An Investigation into the Spectroscopic and Intercalative Proper- ties of Hydrogen Neptunyl Phosphate,” P. K. Dorhout, P. G. Eller, A. B. Ellis, K. D. Abney, R. J. Kissane, and L. R. Avens, Inorg.Ckrn. 28,2926 (1990).

2. “Magnetic Separation as a Plutonium Residue Enrichment Pro- cess,” L. R. Avens, U. F. Gallegos, and J. T. McFarlan, Sep.Sci. TechnoL 25, 1967 (1990).

3. “Synthesis and Characterization of Bis(pentamethyl- cyclopentadienyl) Uranium(IV) and Thorium(IV) Compounds Containing the Bis(trimethylsilyl) Ligand,” S. W. Hall, J. C. Huffman, M. M. Miller, L. R. Avens, C. J. Burns, and A. P. Sattelberger, submitted to Organomet. (January 1992).

130 Nuclear MaterialsTechnology Oivislon Annual Rmlew 4. “The Reaction of Dibenzylmercury with Secondary F’hosphines:Phosphorus-Phosphorus Bond Formation Versus Benzyl Substi- tution,” J. T. Yeh, L. R. Avens, and J. L. Mills, Phosphorus, Sulfur Silicon Relaf. Elem. 47,319 (1990).

5. “Transuranic Organometallics: The Next Generation;’ L. R. Avens, B. D. Zwick, and A. P. Sattelberger, Submitted to ACS Books (1990).

6. “Calculated Phase Equilibria for the CaC~-KCl-MgC~ System,” K. M. Axler, N. J. Pugh, T. G. Chart, H. Daniels, and G. S. Perry, National Physical Laboratory Report DMM(D) 123 (December 1991), National Physi- cal Laboratory, Teddington, UK.

7. “Evaluation of Corrosion Resistant Materials for Use in Plutonium Pyrochemistry,” K. M. Axler, G. D. Bird, and P. C. Lopez, Proc. 180thMeef- ing Elecfrochern. Soc. (1991).

8. “Investigations of Coated Refractory Metals for Plutonium Process- ing,” L. M. Bagaasen, G. L. DePoorter, and K. M. Axler, Trans.Am. Nuc/. Soc. 62,240 (1990).

9. “VolubilityStudies of the Ca-CaO-CaC~ System,” K. M. Axler. Los Alamos National Laboratory report LA-11960-T (July 1991).

10. “VolubilityStudies of the Ca-CaO-CaC~ System,” K. M. Axler and G. L. Del?oorter, Materials Science Forum, Vol. 73-75 (1991), Proc. Third ln- fernafional Symposium on Molten Salt Chemisfy and Technology, Paris, France (June 1991).

11. ‘The Effect of Initial Composition on PuOC1Formation in the Direct Oxide Reduction of PuOz,”K. M. Axler and R. I. Sheldon, ]. Nucl. Mater. 187,183-185 0992).

12. ‘Thermodynamic Modeling and Experimental Investigations of the CsC1-CaC~-PuC~System,” E. M. Foltyn, R. N. Mulford, K. M. Axler, J. M. Espinoza, and A. M. Murray, J. NUCLMater. 178,93-98 (1991).

13. ‘The Structure of

14. “Kynar PVDF assists Los Alamos Labs with Plutonium Recovery Process,” S. M. Dinehart, J. Chem. Process Equip. Des. (1991).

15. ‘Preparation and Structural Characterization of the First Bismuth 1mideComplex Bi3(OtBu)7(NSiMeq),”N. N. Sauer and E. Garcia, submitted ]. Am. Chem. Soc. 0991).

131 P U B LI C AT I O N S

16. “Shock Initiation of I?entaerythritol Tetranitrate Crystals: Steric Effects Due to Plastic Flow,” J. J. Dick, E. Garcia, and D. C. Shaw, Proc. APS 1991 Top.Conf. on Shock Compression of Condensed Matter, Williamsburg, Vir- ginia (June 1991).

17. “Structure and Initial Characterization of 4,6-Bis-(5-amino-3-nitro- IH-1,2,4-triazol-l-y) -5-nitropyrimidine,” K.-Y. Lee, E. Garcia, and D. Barnhart, Los Alamos National Laboratory report LA-12248-MS (March 1992).

18. “Structure of the Laser Host Material LiYF,,” E. Garcia and R. R. Ryan, submitted Acta Crystogra. Sect. C (1991).

19. “Structure of3-Amino, 5-Nitro-l,2,3-Triazole, ~H,N,02,” E. Garcia and K.-Y. Lee, accepted Acta Crystogra. Sect. C. (1991).

20. “Structure of the Hydrazinium Salt of 3-Amino, 5-Nitro-l,2,4- Triazole, Nz~.C#$N~Oz,” E. Garcia, K.-Y. Lee, and C. Storm accepted Acta Crystogra. Sect. C (1991).

21. “Radiometallating Antibodies and Autogenic Peptides,” J. A. Mercer-Smith, J. C. Roberts, D. Lewis, D. A. Cole, S. L. Newmyer, L. D. Schulte, P. L. Mixon, S. A. Schreyer, S. D. Figard, T. P. Burns, D. J. McCormick, V. A. Lennon, M. Hayashi, and D. K. Lavallee, Nezo Trends in Rmfiophmvnaceufical Synthesis, Quality, Assurance, and Regulatory Control, A.M. Emran, Ed. (Plenum Press, New York, 1991).

22. “Synthesis of 4-Alkyl-4-(4-methoxyphenyl)cyclohex-2-en-l -ones and 5-Alkyl-5-phenyl-1, 3-Cylohexadienes from Bis(tricarbonylchromium)-Coordinated Byphenyls,” L. D. Schulte, R. D. Rieke, B. T. Dawson, and S. S. Yang, J. Am. Chem. Soc. 112,8388-8398 - (1990).

23. “Energy Transfer in the “Inverted Region,” Z. Murtaza, A. P. Zipp, L. A. Worl, D. Graff, and T. J. Meyer, J. Am. Chenz.Soc., 113,5113-13 (1991).

24. “Local States in One-dimensional CDW Materials; Spectral Signa- tures for Polarons and BipoIarons in MX Chains,” B. I. Swanson, R. J. Donohoe, L. A. Worl, A. Bulou, C. A. Arrington, J. T. Gammel, A. Saxena, and A. R. Bishop, Mol. Cryst. .Liq.Cryst. 194,43-53 (1991).

25. “Metal-to-Ligand Charge-Transfer (MLCT) Photochemistry: Ex- perimental Evidence for the Participation of a Higher Lying MLCT State in Polypyridyl Complexes of Ruthenium(II) and (II):’ R. S. Lumpkin, E. M. Kober, L. A. Worl, Z. Murtaza, and T. J. Meyer, }. Phys. Chem. 94,239- 43 (1990).

132 Nuclear Materials Technology Division Annual Revimv 26. “Mixed-halide MX Chain Solids: Effect of Chloride Doping on the Crystal Structure and Resonance Raman Spectra of IPt(en),Br,llPt(en),l(CIO,),,”S. C. Huckett,R.J. Donohoe,L. A. Worl, A. Bulou,C. J. Burns,J. R. Laia,D.Carroll,andB. I. Swanson,Chem.Mater. 3,123-7 (1991).

27. “On the Origin of the Resonance Raman VIDispersion and Fine Structure of [Pt(en)2J[Pt(en),Br2](C10,),(PtBr),” S. Huckett,R.J. Donohoe,~ A. Worl, A. Bulou,andB. I. Swanson,SyrzthMet. 42,2773-6 (1991).

28. “Photoinduced Electron and Energy Transfer in Soluble Poly- mers,” S. M. Baxter, W. E. Jones, E. Danielson, L. A. Worl, and T. J. Meyer, Coord.Che?n.Rev. 111,47-71 0991).

29. “Photophysical Properties of Polypyridyl Carbonyl Complexes of Rhenium(I)~’ L. A. Worl, R. Duesing, P. Y. Chen, L. Della Ciana, and T. J. Meyer, J. Chem.Soc., Dalton Trans. (150fh Anniu. Celebration Issue) 849- 58 (1991).

30. “Polarons and Bipolarons in Weak-lD CDWSolids: Spectral Stud- ies of Local States in [Ptn(en)211Ptw(en)2Br21(C IOA)qand [ptn(en)2][pt~(en)m](C10,),,” R. J. Donohoe, L. A. Worl, B. I. Swanson, and A. Bulou, Synfh. Met. 42,2749-52 (1991)

31. “Production and Storage of Multiple, Photochemical Redox Equivalents on a Soluble Polymer,” L. A. Worl, G. F. Strouse, J. N. Younathan, S. M. Baxter, and T. J. Meyer, }. Am. Chem. Soc. 112,7571-8 (1990).

32. “Spectroscopic Studies of Polaron and Bipolaron Defects in the Strongly Localized CDW Solid [PtU(en)2][PtW(en),C~](C10,), R. J. Donohoe, L. A. Worl. A. Bulou, B. I. Swanson, J. Gammel, and A. R. Bishop, Synth.Met. 42,2745-8 (1991).

33. “Ultragap Edge States in Mixed Halide Chain Solids,” B. I. Swanson, R. J. Donohoe, L. A. Wcn-l,J. T. Gammel, A. Saxena, I. Batistic, and A. R. Bishop, A, Synfh. Met. 42,2733-8 (1991).

Publications 133


Nuclear Materials Measurement and Accountability (NMT-4)

In the following publication list, the single underline identifies the author as a group member. If YOUwould like to contact any of these authors, pIease write to them in care of the Nuclear Materials Measurement and Account- ability Group, Mail Stop E513, Los Alamos National Laboratory, Los Alamos, New Mexico 87545.

1. “A Versatile Passive/Active Neutron Coincidence Counter for In-Plant Measurements of Plutonium and Uranium:’ J. R. Wachter, J. E. Stewart, R. R. Ferran, H. O. Menlove, E. C. Horley, J. Baca, and S. W. France, European Safeguards Research and Development Corporation, Avignon, France, Los Alamos National Laboratory document LA-UR-91- 1566 (1991).

Plutonium Metallurgy (NMT-5)

In the following publication list, the single underline identifies the author as a group member. If you would like to contact any of these authors, please write to the Plutonium Metallurgy Group, Mail Stop E506, Los Alamos National Laboratory, Los Alamos, New Mexico 87545.

1. “A Generalized Model of Heat Effects in Surface Reactions, Part 1: Model Development,” J. C. Martz. D. W. Hess, and E. E. Petersen, Los AIamos National Laboratory document LA-UR-92-190, submitted to ]. AppL PhyS. (1992).

2. “A Generalized Model of Heat Effects in Surface Reactions, Part 2: Application to Plasma Etching Reactions;’ J.C. Martz, D.W. Hess, and E. E. Petersen, Los Alamos National Laboratory document LA-UR-92-346, submitted to J. Appl. Phys. (1992).

3. “A Mass Spectrometric Analysis of CFi/O, Plasmas: Effect of Oxygen Concentration and Plasma Power,” J. C. Martz, D. W. Hess, and W. E. Anderson, Plnsma Chem. Plasma Process. 10,261 (1990).

4. “A Plasma-Chemistry-Based Plutonium Contamination Removal Process~’ J. C. Martz, WeaponsComplex Monitor. 1(26),6 (1990).

5. “Alternative Solvents for Cleaning Plutonium: Thermodynamic and Kinetic Considerations,” J. M. Haschke and S. J. Hale, Los Alamos National Laboratory report LA-12255-MS (March 1992).

6. “An )(I?SStudy of the Electronic Structure of Am Metal and Am Dihydride;’ L. E. Cox, T.W. Ward, and R. G. Haire, Phy. Rev. B: Condensed Matter (accepted).

134 Nuclear Materials Technology Division Annual Re\icw 7. “Characterization of Hypervelocity-Microparticle-Impacts (HMI) Utilizing Scanning Electron Microscopy,” J. I. Archuleta, Los Alamos National Laboratory report LA-UR 91-2063 (July 1991).

8. “Core-Level and Valence-Band X-ray Photoelectron Diffraction in UO,(1OO),”L. E. Cox and W. P. Ellis, Solid State Commun. 78,1033 (1991).

9. “Debye-Wailer Factors of d-Phase PuO,g~AIO,Kbetween 15 and 90 K,” A. C. Lawson, J. Vaninetti, J. A. Goldstone, R. I. Sheldon, and & ~ in LANSCE Experiment Reports, Los Alamos National Laboratory re- port LA-12194-PR (October 1991), p. 128.

10. “Demonstration of Plutonium Etching in a CFq/OzRF Glow Discharge,” J. C. Martz. D. W. Hess, J. M. Haschke, J. W. Ward, and B. F. Flamm, J. Nucl. Mater. 182,277(1991).

11. “Elastic Properties of Materials by Pulsed Neutron Diffraction,” A. C. Lawson, A. Williams, J. A. Goldstone, D. T. Eash, R. J. Martinez, J. I. Archuleta, D. J. Martinez, B. Cort, and M F. Stevens, ]. Less-Common Met. 167,353-363 (1991).

12. “Electronic Structure of Hydrogen and Oxygen Chernisorbed on Plutonium: Theoretical Studies:’ O. Eriksson, Y. G. Hao, B. R. Cooper, G. W. Fernando, L. E. Cox, T.W. Ward. and A. M. Boring, Phys. Rev. B 43, 4590 (1991).

13. “Electronic, Structural, and Transport Properties of (Almost) Rare-Earth-LilceActinide Hydrides,” J. W. Ward, B. Cort, J. A. Goldstone, A. C. Lawson, and L. E. Cox, in TrarzsuraniumElements: A FIalj-Centuy, American Chemical Society (May 1992).

14. “Hydrolysis of Plutonium: The Plutonium-Oxygen Phase Diagram,” J. M. Haschke, in Transuranium Elements: A Half-Centuy, American Chemical Society (May 1992).

15. “IBM-PC Software for Analysis of Internal Friction Peaks to Obtain Relaxation Time Spectra,” J. R. Cost, Los Alamos National Labora- tory document LA-UR-91-2430, September 1991.

16. “Kenetics of Helium Outgassing from FCC-Stabilized Plutonium,” J. C. Kammer and J. R. Cost, Los Alamos National Laboratory document LA-UR-91-1445 (1991).

17. “Magnetic Structures of Actinide Materials by Pulsed Neutron Diffraction,” A. C. Lawson, J. A. Goldstone, J. G. Huber, A. L. Giorgi, J. W. ConanL A. Severing, B. Cort, and R. A. Robinson, J. AppL Phys. 69(8), 5112-5116 (1991).

Pubkatiom 135


18. “Mechanical After-Effect Studies of Oxygen Relaxation in YBaz:’ J. R. Cost and T. Stanley, Los Alamos National Laboratory document - LA-UR-91-2736 (September 1991).

19. “MechanicalAfter-EffectStudiesof OxygenRelaxationin YBazC~Ozd”R. CostandJ. T. Stanley.LosAlamosNationalLaboratory documentLA-UR-911569(1991).

20. “Neutron Diffraction Study of Alpha, Beta, and Gamma Phases of ,” J. A. Goldstone, A. C. Lawson, B. Cort, and E. Foltyn, in LANSCE Experiment Reports, Los Alamos National Laboratory report LA- 12194-PR (October 1991).

21. “Partial Pressure Analysis of CFqOzPlasmas,” J. C. Martz, D. W. Hess, and W. E. Anderson, in Plasma Surface Interactions and Process- ing of Materials, O. Auciello et al., Eds., (Kluwer Academic Publishers, Netherlands, 1990).

22. “Plutonium Dry Machining,” M. R. Miller, Los Alamos National Laboratory document LA-UR-91-2261 0991).

23. “Structures of the Three Phases of PaDP” J. W. Ward, B. Cort, J. M. Haschke, A. C. Lawsoq R. B. Von Dreele, and J. C. Spirlet, in LANSCE Experiment Reports, Los Alamos National Laborato”~report LA-12194-PR (October1991).

24. “Tantalum Etching in Fluorocarbon/Oxygen RF Glow Dis- charges,” J. C. Martz, D. W. Hess, and W. E. Anderson, ]. Appl. Phys. 67, 3609 (1990).

25. “Vibrational Properties of PuH<” J. A. Goldstone, A. C. Lawson, J. Eckert, L. Diebolt, B. Cort, l.W. Ward and 1.M. Haschke, in LANSCEEx- periment Reports, Los Alamos National Laboratory report LA-12194-PR (Oc- tober 1991).

Actinide Materials Chemistry (NMT-6)

In the folIowing publication list, the single underline identifies the author as a group member. If you would like to contact any of these authors, please write to them in care of the Actinide Chemistry Group, Mail Stop E51O,Los Alamos National Laboratory, Los Alamos New Mexico 87545.

1. “A Small-Scale Study on the Dissolution and Anion-Exchange Re- covery of Plutonium from Rocky Flats Plant Incinerator Ash:’ T. W. Blum, R. G. Behrens, V. J. Salazar, and l?. K. Nystrom, Los Alamos National Labo- ratory report LA-11747-PR (June 1991).

136 Nuclear Malwi.IlsTcchnology Divlslon kmual Rm&v 2. ‘The Irreversible Adsorption of Plutonium Hexafluoride,” G. M. Cam~bel~ Los Alamos National Laboratory document, Chern.Eng. Commun., in press.

3. “A Kinetic Study of the Equilibrium Between Dioxygen Monofluoride and Dioxygen Difluoride,” G. M. Campbell, ]. HuorirzeChem, 46,357-366 (1990).

4 ‘Trimethylborane,” W. Rees, M. Hampton, S. W. Ha11,and J. Mills, A. P. Ginsberg, editors, Inorg.Synth. 27,339 (TexasTech University, 1990).

5. “vibrational Properties of Actinide (U, Np, Pu, Am) Hexafluoride Molecules,” K. C. Kim and R. N. Mulford, J. Mof. Sfruct. 207,293 (1990).

6. “Sublimation Studies of NpO,F,,” P. D. Kleinschmidt, K. H. Lau, and D. L. Hildenbrand, submitted to J. Chern.Phys. (1990).

7. “Free Energy of Formation of CS,PUC1,and CsPu,C~,” M. A. Williamson and P. D. Klein~chmidt, submitted to the}. A?ucl.ivlafer. (1992).

8. “A Chemical Exchange System for Isotopic Feed to a Nitrogen and Oxygen Isotope Separation Plant,” T. R. Mills, M. G. Garcia, R. C. Vandervoort, and B. B. McInteer, Sep. Sci. TechnoL 24,415 (1990).

9. “Silicon Isotope Separation by Distillation of Silicon Tetrafluonde,” T. R. Mills, Sep. Sci. Technol. 25 (3), 335 (1990).

10. “PracticalSulfurIsotopeSeparation by Distillation:’ T. R. Mills, Sep.Sci. TechnoL25(13-15), 1919 (1990).

11. “Synthesis of Liquid-phase Dioxygen Difluoride,” T. R. Mills, J. Fluorine Clzem.52(3), 267 (1991).

12. “Superheavy Isotope Enrichment Using a Carbon Isotope Enrich- ment Plant,” B. B. McInteer and T. R. Mills, Sep. Sci. Techrzol., 26(5), 607 (1991).

13. ‘Thermodynamics Modelling and Experimental Investigation of the CsC1-CaC~-PuC~System,” E. M. Folytn, R. N. R. Mulford, K. M. Axler, J. M. Espinosa, and A. M. Murray, J. NUCLMater. (1990).

14. “Cooperative Two-Photon Induced Chemical Bond Formation during a KrFzCollision to form KI-F,”T. O. Nelson and D. W. Setser, Chem. Phys. L.eff., 170,430 (1990).

15. “Two-Photon Direct Laser-Assisted Reaction between Xe and ClY:’ J. Qin, T. O. Nelson, and D. W. Setser, J. Phys. Chem., 95,5374 (1991).

Publications 137 P U B L! CAT I O N S

16. “QuenchingConstants of KrF(B,C) by Krand Xeand the KrF(B,C) Equilibrium Constant:’ W. Gadomski, J. Xu, D. W. Setser, and ~ Nelson, Che~. Phys. Left. 189,153(1992).

17. “interpretations of the Two-Photon Laser-Assisted Reactions of Xe with Cl, Fz,CIF, and Kr with Fz,”T. O. Nelson, D. W. Setser, and J. Qin, j. Phys. Chem. submitted (1992) KSU.

18. “Quenching Rate Constants of the Xe(5ps6p)Excited States and the Associative Ionization Reaction of the Xe (5p56s[3/2],)Atoms:’ T. O. Nelson and D. W. Setser, J. Phys. Chem., submitted (1992).

19. “F-Element Compound Synthesis Employing Powerful Halogenat- ing Agents,” P. G. Eller, S. A. Kinkead, and J. B. Nielsen. 50th Anniversary of the Discovery of the Transuranium Elements, Nonseries ACS Book, 1991, Ac- cepted. Los Alamos National Laboratory document LA-UR-90-2712 (1990).

20. “A New Synthesis of XeOF4,”J. B. Nielsen, S. A. Kinkead, P. G. Eller, Inorg. Chem. 29,3621 (1990).

21. “Synthesis of New Perfluorotertiary Amines Containing Geminal Pentafluorosulfanyl, SF~,Groups:’ J. B. Nielsen, J. S. Thrasher, ). Fh{orine Chem. 48,407 (1990).

22. “New Syntheses of Xenon Hexafluoride, XeFb and Xenon Tet- rafluoride, XeFq,”J. B. Nielsen, S. A. Kinkead, J. D. Pu~son,and P. G. Eller, I~lorg.Chem. 29,1779 (1990).

23. “Studies on Advanced Oxidizer Systems Containing the Fluoroperoxide Moiety,” S. A. Kinkead, P. G. Eller, and J. B. Nielsen, Los Alamos National Laboratory document LA-UR-90-651 (1990).

24. “Synthesis and Identification of (NH4)ZPUC1Gand (NH,)zUClband Preparation of PuC~,” J. Nielsen, S. A. Kinkead, and P. G. Eller, 50fh Anni- versary of the Discovery of the Transuranium Elements, Nonseries ACS Book, 1991, Los Alamos National Laboratory document LA-UR-90-2692 (1990).

25. “Direct Comparison of Low Light Level Detectors: The Imaging PMT and CCD,” D. K. Veirs, J. W. Ager III, and G. M. Rosenblatt, to be submitted (1992).

26. “15NNuclear Magnetic Resonance Spectroscopy Studies of the Nitrate Complexes of Thorium;’ S. W. Hal~ L. R. Avens, D. K. Veirs, and B. D. Zwick, to be submitted (1992).

27. “Spatially-Resolved Raman Studies of CVD Diamond Films;’ ]. W. Ager III, D. K. Veirs, and G. M. Rosenblatt, Phys. Rev. Sect. B 43,6491 (1991).

138 Nuclear Materials Technol~ Division Annual Review 28. “Materials Characterization by Imaging Raman Spectroscopy,” D. K. Veirs, J. W. Ager III, and G. M. Rosenblatt, Adv. Compos. Mater. 19, 1043 (1991).

29. “Raman and Resistivity Investigations of Carbon Overcoats of Thin Film Media - Correlations with Tribological Properties,” B. Marchon, N. Heiman, M. R. Khan, A. Lautie, J. W. Ager III, and D. K. Veirs, J. Appl. Phys. 69,5748 (1991).

30. “Vibrational Raman Characterization of Hard-Carbon and Dia- mond Films:’ J. W. Ager III, D. K. Veirs, B. Marchon, N.-H. Cho, and G. M. Rosenblatt, Applied Spectroscopy in Maferial Science, D. D. Saperstein, Ed., Proc. SPIE 1437,24 (1991).

31. “Spectrophotometric Investigation of the Pu(IV) Nitrate Complex Sorbed by Ion Exchange Resins,” S. F. Marsh, R. S. Day, and D. K. Veirs, Los Alamos National Laboratory report LA-12070 (June 1991).

32. “Mapping Materials Properties with Raman Spectroscopy Utiliz- ing a Two-Dimensional Detector,” D. K. Veirs, J. W. Ager III, E. T. Loucks, and G. M. Rosenblatt, Appl. Opt. 29,4969 (1990).

33. “Chemical Structure and Physical Properties of Diamond-Like Amorphous Carbon Films Prepared by Magnetron Sputtering,” N.-H. Cho, K. M. Krishnan, D. K. Veirs, M. D. Rubin, C. B. Hopper, B. Bhushan, and D. B. Bogy, ~.Mater. Res. 5,2543 (1990).

34. “TransientSubcriticalCrack-GrowthBehaviorin Transformation- ToughenedCeramics,”R. H. Dauskardt,D. K. Veirs,W. C. Carter,and R.O.Ritchie,Acta Mefall. Mater. 38,2327 (1990).

35. “Laser Heating Effects in the Characterization of Carbon Fibers by Raman Spectroscopy,” J. W. Ager III, D. K. Veirs, J. Shamir, and G. M. Rosenblatt, ). AppL Phys. 68,3598 (1990).

36. “Raman Characterization of High Temperature Materials using an Imaging Detector,” G. M. Rosenblatt and D. K. Veirs, HighTemp. Sci. 26,31 (1990).

37. “Mapping Chemical and Physical Properties of Advanced Materi- als Using Spatially-Resolved Raman Spectroscopy,” D. K. Veirs, J. W. Ager III, and G. M. Rosenblatt, Proc. Twelfth International Conference on Raman Spectrosc., J. R. Durig and J. F. Sullivan, Eds. (John Wiley and Sons, Chichester, 1990), p. 898.

38. “Interference Effects in the Raman Spectroscopy of Thin Films,” G. M. Rosenblatt, J. W. Ager III, and D. K. Veirs, Raman Spectrosc., J. R. Durig and J. F. Sullivan, Eds. (John Wiley and Sons, Chichester,

Publication 139 P U B LI CAT I O N S

Nuclear Materials Management (NMT-7)

In the following publication list, the single underline identifies the author as a group member. If you would like to contact any of these authors, please write to them in care of the Nuclear Materials Management Group, Mail Stop E524, Los Alamos National Laboratory, Los Alamos, New Mexico 87545.

1. “Addressing Mixed Waste in Plutonium Processing,” D. C. Christensen and C. L. Sohn, Proc. Spec. Symp. EvzergingTechnol. for Hazard. WasteManage., Am. Chern. Soc., Atlanta, Georgia, 8-11 (October, 1991).

2. “Waste Management: A Integrated Modeling Aproach for Ana- lyzing Change in NWC Production Processes;’ D. C. Christensen, C. L. Sohn, T. M. Helm, and T. J. Fansh, Proc. 7fh Annu. Dep. Energy Model Conf., Oak Ridge, Tennessee, (October 1991).

3. ‘Treatment of Off-Spec Cemented Waste at LANL,” G.W. Veazev, to be published in Proc. Workshop Radioacf. Hazard. and/or Mixed Wasfe Man- age. (ORNL), Knoxville, Tennessee, Los Alamos National Laboratory docu- ment LA-UR-90-4389 (December 1990).

4. ‘The Cement Solidification Systems at LANL,” G.W. Veazev, to be published in the Proc. Workshop Radioacf. Hazard. and/or Mixed Waste Man- age. (OR.AUJ,Knoxville, Tennessee, Los Alamos National Laboratory docu- ment LA-UR-90-4161 (December 1990).

5. “Radiolysis Effects in Gypsum Cements Used for Fixation of TRU Wastes;’ G.W. Veazev and P.D. Shalek,-to be published in Issue 21 of Wasfe Mmmgemenf Research Absfracfs, IAEA, (1992).

6. “Modular Plutonium Processing Facility Simulation,” K.M. Gruetzmacher, P.K. Nvstrom, T.F. Yarbro, and C. Alton Coulter, Los AIamos National Laboratory document LA-UR-91-1807 (1991).

140 Nuclear Materials Tcchamlogy Dirlslon Annual Rcvtew Heat Source Technology (NMT-9)

In the following publication list, the single underline identifies the author as a group member. If you would like to contact any of these authors, please write to them in care of the Heat Source Technology Group, Mail Stop E502, Los Alamos National Laboratory, Los Alamos, New Mexico 87545.


1. ‘Twinnin gin Monoclini Beta Phase Plutonium:’ T. G. Zocco, R. I. Sheldon, and H. F. R.izzo,). Nzfcl.Mater. 183,80-88 (1991).

2. “Correction to the Uranium Equation of State,” R. I. Sheldon and R.N. R. Mulford, ]. Nucl. Mater. 185,297-298 (1991).

3. The Effect of Initial Composition on PuOC1Formation in the Di- rect Oxide Reduction of Pu02,” K. M. Axler and R. L Sheldon, to be pub- lished in]. Nucl. Mater.


“Milliwatt Generator Project, April 1986- March 1988/’T. W. Latimer and G. H. Rinehart, Los Alamos National Laboratory report LA-12236-PR (in press).

Group Profiles 141 142 Nuclear MaterLdsTcchnology Division Annual Re\lcw

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