1st quarter 2001 TheLos Actinide Alamos National Research Laboratory N u c l e a r M Quarterlya t e r i a l s R e s e a r c h a n d T e c h n o l o g y

Researcher Provides a Historical Perspective for Plutonium Heat Sources In This Issue We begin the seventh year of Actinide Research Quarterly For more than 30 years, by focusing on Los Alamos has designed, major programs in 4 developed, manufactured, NMT Division. The Pit Manufacturing and tested heat sources for publication team Project Presents Many radioisotope thermoelectric also welcomes its Challenges generators (RTGs). These new editor, Meredith powerful little “nuclear “Suki” Coonley, who is 6 batteries” produce heat assuming the position Can Los Alamos from the decay of radioac- while Ann Mauzy Meet Its Future Nuclear tive isotopes—usually takes on acting Challenges? plutonium-238—and can management provide electrical power duties in IM-1. 9 and heat for years in Detecting and satellites, instruments, K.C. Kim Predicting Plutonium and computers. Aging are Crucial to continued on page 2 Stockpile Stewardship

12 Pit Disassembly and Conversion Address a ‘Clear and Present Danger’

14 Publications and Invited Talks

Newsmakers

15 Energy Secretary Spencer Abraham Addresses Employees artist rendering of Rover Pathfinder on Mars from NASA/JPL

Nuclear Materials Technology/Los Alamos National Laboratory 1 Actinide Research Quarterly

This article was contributed by Gary Rinehart (NMT-9) Early development efforts from the Each Multihundred Watt RTG provided about 157 mid-1960s through the early 1970s focused watts of power at the beginning of the mission. on fuel forms for space applications. The first, To meet the larger power requirements of plutonia-molybdenum-cermet (PMC), was the Galileo, Ulysses, and Cassini missions in used on the Pioneer 10 and 11 missions to the late 1970s, Los Alamos developed the Jupiter and Saturn and the Viking Lander General Purpose Heat Source (GPHS). This missions. PMC was fabricated by hot-pressing RTG contained 572 silicon germanium ther- microspheres of molybdenum-coated plutonia moelectric couples into hockey-puck-shaped discs, which were inside a thermoelectric then stacked and encapsulated in a converter and pro- refractory alloy. vided 285 watts of During the same period, Los Alamos electrical power at developed a medical-grade fuel for use in the beginning. cardiac pacemakers and early artificial hearts. The heat source The fuel in the artificial hearts was made of 90 for these RTGs con- percent enriched plutonium-238 and provided sisted of 18 GPHS up to 50 watts of power. Some of the early modules. Each module pacemakers are still in use; some have been had four fueled clads returned to Los Alamos’ Plutonium Facility and each cylindrical for recovery. fueled clad contained a hot-pressed 150- A General Purpose Heat gram pellet of Source (GPHS) fueled plutonium-238 dioxide clad. encapsulated in an iridium-tungsten container. Los Alamos fabricated the 216 GPHS fueled clads used on the Cassini mission. Each iridium clad contained a sintered iridium powder frit vent designed to release the helium generated by the alpha particle decay of the fuel. The iridium is compatible with Los Alamos developed As electrical power requirements for plutonium dioxide at temperatures greater a General Purpose spacecraft increased during the 1970s, so did than 1,773 K and melts at 2,698 K. Heat Source (GPHS) in the need to increase the power density of the In addition to developing RTGs to provide the late 1970s to meet heat source. Using “inert” materials such as electrical power to operate instruments, Los the larger power molybdenum proved unattractive. Los Alamos Alamos also designed and fabricated heater requirements of the began investigating fuel forms that used pure units to keep equipment operating in the Galileo, Ulysses, plutonia, which can generate more power in deep-freeze of space. The Light Weight and Cassini a smaller, lighter package. Radioisotope Heater Unit (LWRHU) provided space missions. The first pure plutonia fuel form one thermal watt of heat and was used on the developed at Los Alamos was the Galileo and Cassini spacecraft and Mars Multihundred Watt (MHW) for the RTGs used Pathfinder Rover. At the heart of this heater on the Voyager 1 and 2 missions to Jupiter, unit was a platinum-30 percent rhodium Saturn, Uranus, and Neptune. The heat source fueled clad containing a hot-pressed was a 100-watt hot-pressed sphere of plutonia 2.67-gram pellet of plutonium-238 dioxide. encapsulated in iridium. Twenty-four heat Los Alamos has also fabricated a large sources were contained within the RTG. Heat number of heat sources for the weapons was converted to electrical power by 312 program. From 1981 to 1990 more than 3,000 silicon-germanium thermoelectric couples. Milliwatt Generator (MWG) heat sources were

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fabricated and shipped to the Pinellas, Fla., A significant amount of the heat source plant for assembly into the MWG-RTG. These fuel in the Los Alamos inventory, including the RTGs were used in devices that reduce the Russian material and fuel from disassembled possibility of accidental detonation from a terrestrial heat sources, must be purified nuclear warhead. Each of the Milliwatt before it can be fabricated into new heat Generator heat sources had a nominal power sources. Heat source fuel was previously of 4.0 to 4.5 watts. Los Alamos is currently recycled and purified at Savannah River. recovering fuel from excess MWG-RTGs and Los Alamos is qualifying a plutonium-238 performing shelf-life and stockpile surveil- aqueous recovery lance on both the MWG heat source and the process in its pluto- MWG-RTG. See Actinide Research Quarterly, nium facility to Winter 1994, “Milliwatt Surveillance Program provide feed for the Ensures RTG Safety and Reliability.” heat-source fabrica- Historically, reactors at Savannah River tion process. produced all of the United States’ plutonium- A new glove-box 238 until the late 1980s. With the shutdown of line is being installed the Savannah River reactors, the United States for this work and the has had to purchase plutonium-238 dioxide full-scale aqueous from Russia to supplement U.S. inventories recovery process is for future NASA space missions. Recently, the expected to become DOE has proposed that plutonium-238 be pro- operational this fiscal duced at the Advanced Test Reactor (ATR) in year, which will have the capacity to purify A Light Weight Idaho and the High Flux Isotope Reactor 5 kilograms of plutonium-238 per year. In Radioisotope Heater (HFIR) at Oak Ridge National Laboratory. addition, Los Alamos has the capability of Unit (LWRHU) before fabricating more than 5 kilograms of final assembly. The heat source consists of a plutonium-238 into heat sources per year. graphite aeroshell, These improvements to the plutonium pyrolytic graphite facility will ensure that Los Alamos can fully thermal insulators, and support future NASA requirements. The a platinum-rhodium Europa Orbiter mission, scheduled for launch fueled clad. A sintered in 2006, and the Solar Probe mission, scheduled platinum powder frit vent for launch in 2007, will each require approxi- is electron-beam-welded mately 3 kilograms of plutonium-238 if a into the end cap of the Stirling radioisotope power system were fueled clad to release used. If RTGs are used, approximately helium generated by the 8 kilograms of plutonium-238 will be alpha decay of the fuel. required for each mission. Over the next decade, several Mars exploration missions will carry LWRHUs, which will require approximately 0.3 kilogram of plutonium-238 per mission. In the long term—the next 20 to 35 years—NASA is expected to need 2 to 5 kilograms of plutonium-238 per year for its space missions.

The Mars Pathfinder Rover contained three Light Weight Radioisotope Heater Units (LWRHUs).

Nuclear Materials Technology/Los Alamos National Laboratory 3 Actinide Research Quarterly

Pit Manufacturing Project Presents Many Challenges This article was contributed by David Mann and Sean McDonald, Central to the function of a thermonuclear final assembly of the nuclear and nonnuclear NMT-5 weapon is a plutonium pit, the trigger that ini- components. Complicating matters are the tiates the sustained nuclear reaction. Los changes that have had to be made in a substan- Alamos’ experience in making pits dates back tial number of these processes because of the more than 50 years, to the Manhattan Project. unavailability of the original equipment, Since that time, the Lab has produced a small the need to comply with new environmental number of pits—about a dozen a year—for regulations, or the ability to take advantage research purposes and underground testing of improved equipment. in Nevada. By comparison, the number of pits NMT has faced a number of challenges produced yearly at the now-closed Rocky in setting up these capabilities. The first and Flats defense plant near Denver was in probably most significant challenge has been the thousands. to set up a formal manufacturing operation— In 1993, the Department of Energy (DOE) with all its controls, infrastructure, and requested that Los Alamos develop the manu- restrictions—in an existing research and facturing capabilities to produce war-reserve development facility, and to do so without pits as part of the stockpile stewardship pro- completely disrupting the existing programs. gram. The designation “war reserve” means To manufacture pits to the same specifications that the components meet the specifications as Rocky Flats, each of the more than 100 pro- required for use in a stockpiled nuclear cesses involved has had to be installed, tested, weapon. Los Alamos was chosen in part and proven to function as it did at Rocky Flats. because it has the nation’s only full-capability Currently, more than 98 percent of these pro- plutonium facility. DOE plans call for Los cesses have been installed and used in the A casting furnace in Alamos to develop the capability to make development program designed to prove the operation. 20 to 50 pits a year eventually. effectiveness of either new procedures or sig- Los Alamos nificant modifications to procedures used at established the Pit Rocky Flats. Manufacturing With the suspension of underground testing Project to coordinate following the advent of the Nuclear Test Ban the activities of the Treaty, scientists currently have no way to many divisions across prove absolutely that any production changes the Laboratory do not affect the pits. Because of this, each pro- involved in pit cess that has undergone any significant change manufacturing. With must go through a formal process qualification support from many plan, which consists of a series of experiments Lab divisions—Engi- designed to capture the possible variables of neering Sciences and the new system. The process qualification plan Applications (ESA), is followed by an independent statistical analy- Materials Science and sis of the data by D Division before the process Technology (MST), is fully approved. Chemistry (C), and The development program consists of 10 Decision Applications development pits, each of which tests one or (D—the Nuclear more areas of concern to physicists or design Materials Technology engineers. As part of the development pro- (NMT) Division is gram, researchers will test the fabrication and developing and assembly processes to identify and solve implementing potential problems that may occur in the sub- processes that sequent qualification and production lots. The range from casting development program also includes training the plutonium to the personnel in nuclear manufacturing processes,

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providing destructive evaluation results for when it becomes too contaminated to process feedback where this information can’t effectively clean the components. be obtained nondestructively, and establishing As a long-term solution, a new method an assembly information database for Los using carbon dioxide as the cleaning agent is Alamos manufacturing methods suitable for being developed to completely replace the predicting process yields for actual solvent cleaning system. This will allow the production runs. plutonium components to be cleaned in an The development pits will be followed by a environmentally benign method, producing series of qualification pits, which will be made negligible waste. completely to war-reserve specifications. These In addition to a multitude of manufacturing pits will be used in the certification program. challenges, NMT faces two challenges in the One of the manufacturing challenges is quality arena. A technical challenge is to pro- the selection of process materials to be used vide a more formal method than what was during fabrication, many of which have used at Rocky Flats for qualifying processes changed over the years. To remedy this, the and documenting the qualification. War Reserve Materials Compatibility Board A regulatory challenge is to institute a (WRMCB) has been established to evaluate quality-assurance system that meets the DOE’s process materials for use in war-reserve manu- strenuous requirements for war-reserve com- facturing. The WRMCB reviews historical data ponents, and to do so without the substantial obtained from Rocky Flats to make a determi- resources that were devoted to the quality nation on whether or not a process material is department at Rocky Flats. To meet the regula- compatible for use with plutonium or other tory challenge, small, specialized teams have war-reserve metals. If there isn’t enough his- been formed to qualify processes and write a torical information to make a determination, documented manufacturing manual. the WRMCB commissions a compatibility Despite the large number of challenges study to be performed by the Materials facing the pit manufacturing process, the Testing Laboratory in C-ACT. project has had many successes and is on Another challenge for project researchers schedule to meet all of the major milestones has been the changing environmental regula- for producing a certifiable pit by 2003 and a tions controlling the use of organic solvents. fully certified pit by 2007. At Rocky Flats, plutonium components were This is a significant achievement, cleaned with trichloroethane, which is now particularly in light of last spring’s Cerro banned by the Montreal Protocols. Another Grande Fire, during which the plutonium solvent, trichloroethylene (TCE), is currently facility was completely shut down for several being used, but it is a suspected carcinogen. weeks. The first pit produced following the Besides its potential health risk, TCE is fire was made on schedule just weeks after the extremely costly to dispose of when it’s con- facility reopened. A second pit was produced taminated with plutonium. several weeks later to test the quality- and NMT Division is resolving these issues production-control systems. with a multilevel approach. NMT-11, in The next stage of development is to conjunction with C-PCS, has developed a complete the process qualification plans and hydrothermal technique for destroying TCE implement formalized work instructions for by reducing it to water, carbon dioxide, and each process. These will be completed by the hydrochloric acid. To reduce the amount of April 2002 milestone, along with all of the sup- TCE produced while this system is being port and quality systems necessary to satisfy installed, NMT-5 and C-ACT have developed war-reserve requirements for documentation a cleaning system that reduces by 75 percent and quality. the amount of solvent used. The groups are also developing a method to recycle the TCE

Nuclear Materials Technology/Los Alamos National Laboratory 5 Actinide Research Quarterly

Editorial Can Los Alamos Meet Its Future Nuclear Challenges? Balancing the Need to Expand Capabilities While Reducing Capacity

Editor’s note: Tim George is head of the Nuclear Los Alamos also maintains significant Materials Technology (NMT) Division. In this, his capabilities for actinide research and processing first editorial for Actinide Research Quarterly, he in a much older facility, the Chemistry and discusses some of the challenges facing the division. Metallurgy Research (CMR) Building, which opened in 1952. The CMR Building consists of Since the early 1980s, the vast array of seven wings that house two banks of hot cells, Department of Energy (DOE) facilities once laboratories designed for actinide materials NMT Division Director devoted to the study and use of actinide mate- science and analytical chemistry, and unique Tim George. rials has undergone a dramatic restructuring. capabilities for working with actinide metals. Sites such as Mound, Ohio; Pinellas, Fla.; The seven wings of the CMR Building Hanford, Wash.; and Rocky Flats, Colo., which originally contained more than 50,000 square The opinions in this editorial are the once formed the backbone of the nation’s feet of nuclear laboratory space. By 2001, how- author’s. They do not necessarily represent the opinions of weapons complex, have either closed outright ever, degradation of critical support systems Los Alamos National Laboratory, or exchanged well-defined production and resulted in a suspension of activities in one the University of California, the Department of Energy, or the support missions for goals of decontamination wing, increasingly stringent requirements for U.S. government. and decommissioning. operational safety resulted in suspension of DOE’s remaining active sites are handicapped operations in a second, and planned decommis- in the near term by deteriorating nuclear and sioning of a third wing reduced the amount of high-hazard facilities, and infrastructure bud- usable nuclear laboratory space to approxi- gets that in most cases are inadequate to mately 28,000 square feet. address a half-century of accumulated liabilities. In the 1990s, Los Alamos embarked on an Although also burdened with its share of aggressive program of upgrades to ensure con- aging facilities, Los Alamos is unique in that it tinued safe operation of the CMR Building continues to operate the nation’s only full-service through 2010. By early 2001, approximately plutonium facility. Building PF-4, which is $76 million had been spent on the CMR located at TA-55, is both the newest (it opened in upgrades, of which about one-half consisted 1978) and only remaining facility in the DOE of urgent maintenance items, with the balance complex with the capability to conduct opera- directed toward upgrading building systems tions with all isotopes and chemical forms of to meet regulatory requirements and to ensure plutonium, as well as other actinides. These continued safe operations. diverse capabilities are packed into approxi- Planned and completed upgrades included mately 80,000 square feet of nuclear HEPA filter replacement in operational wings, laboratory space. upgrades to the fire protection system, improvements to exhaust stack monitoring systems, major upgrades of facility electrical systems, and safety-driven improvements to the building personnel accountability system.

The CMR Building, which opened in 1952 and consists of seven wings that house two banks of hot cells, laboratories designed for actinide materials science and analytical chemistry, and unique capabilities for working actinide metals.

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Recent experience has demonstrated that substantial additional maintenance will be required to reduce the probability of unplanned outages resulting from the failure of aging and obsolete building systems. Together, the Plutonium Facility and the CMR Building represent a lifeboat for preserving the nation’s most critical nuclear technologies until they can be transitioned to the facilities of the future. In the near term, an increasing workload in support of production and sup- port missions is competing for limited CMR and PF-4 floor space. These missions currently include pilot production of nuclear defense components; surveillance of defense components; fabrication of components used in subcritical experi- ments; small-scale production of plutonium heat sources, analytical standards, and In the case of the Plutonium Facility, the The entrance to the advanced nuclear fuels; materials surveillance; outlook is for increased facility maintenance TA-55 Plutonium development and implementation of tech- and operational costs as the facility ages. Facility. nologies for materials disposition; and Because PF-4 has operated for nearly 25 years investigative research. with no comprehensive plan for capital Of these missions, the most difficult to reinvestment and with limited budgets for prioritize is investigative research. However, facility maintenance and operation, unplanned history has repeatedly demonstrated that outages will become increasingly common as aggressive programs to understand today’s components in key facility systems reach the bench-top curiosities are the only certain end of their design lifetimes. means to avoid being on the wrong end of In addition, facility resources are stretched tomorrow’s technological surprises. even further by requirements to meet regula- The challenge then, for the Nuclear tory and operational standards that were not Materials Technology (NMT) Division, which in place, or even envisioned, at the time the operates both PF-4 and the CMR Building, is facility was constructed. twofold: to ensure continued success in cur- The goal of reducing excess capacities rent and future programmatic missions, and while preserving and expanding technical to preserve and expand technical capabilities capabilities will be much more difficult to while reducing the space and resources achieve than completion of well-defined devoted to excess capacities. programmatic assignments. The most critical factors to ensuring The key factors to success in this area are NMT’s success in completing programmatic by nature subjective. Assumptions must be assignments are adequate and sustained bud- made on the probabilities of increased or gets for facility operations and maintenance. decreased program requirements for the Although the CMR upgrades project has outputs of various processes. Predictions must addressed the most critical deficiencies in the also be made on the significance and opera- facility, additional investment will be required tional requirements of emergent technologies, to address the failure of aging and obsolete such as room-temperature ionic liquids, that nonsafety-related systems. offer the promise of reducing the need for, or even replacing, current separations processes.

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Both sets of assumptions and predictions Significant questions remain as to how must then be compared with existing facility long PF-4 and the CMR Building can be configurations to identify specific laboratories expected to remain operational given current and glove boxes (currently devoted to excess and expected facility budgets and when new process capacities) that may be suitable for facilities will be available to house trans- reconfiguration. Finally, funds must be itioned operations. Questions also remain identified to reconfigure these laboratories about the long-term effects of compromises for other uses. necessary to maintain production, program- With sufficient budget, there are matic support, research, and development significant opportunities to reclaim the within the limited space available in these space occupied by excess process capacities. two facilities. In PF-4, for example, which was originally Given the long lead time needed for designed as the nation’s premier actinide construction of nuclear facilities and the lim- research and development facility, a portion ited remaining lifetime of the CMR Building, of the facility remains configured to separate decisions must be made soon on the size, and purify relatively large quantities of location, and capabilities of the DOE’s plutonium and other actinides. reconfigured nuclear complex. Although these capabilities made At Los Alamos, work needs to accelerate significant contributions to the nation’s on replacing the CMR Building with a new defense in the early 1980s, it is unlikely that facility (or a set of smaller, cheaper facilities), they will ever again be required to operate on and on development and implementation of that scale. Consolidation of the separations the Integrated Nuclear Park (INP) concept processes into a smaller footprint offers the proposed by Gen. John Gordon, head of the potential to free up space that can then be National Nuclear Security Administration used to support increasing programmatic (NNSA). The INP, if implemented, would workloads, emergent technologies, or waste consolidate all Los Alamos nuclear opera- reduction and treatment processes required to tions into one area. meet new regulatory standards.

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Detecting and Predicting Plutonium Aging Are Crucial to Stockpile Stewardship This article was contributed by David Clark and During the past decade we have seen Within this new environment, the Joseph Martz, unprecedented changes in the world’s political Department of Energy (DOE) has implemented G. T. Seaborg climate. The end of the Cold War, the breakup the Science-Based Stockpile Stewardship Institute, NMT of the former Soviet Union, strategic arms Program, which relies on the use of methods Division reduction treaties—all have contributed to other than nuclear testing to ensure the safety, a decrease in nuclear arms buildup. These security, and reliability of the stockpile. These changes notwithstanding, nuclear weapons methods include advanced diagnostic equip- technology continues to play a key role in ment, data from critical new experiments, reducing the global nuclear danger. enhanced computational power, and retaining However, the configuration of the the very best scientists and engineers at the weapons complex is far from static. The size nation’s nuclear research facilities. and number of nuclear weapons within the Several new missions are growing in U.S. arsenal have been dramatically reduced, importance, including the analysis and surveil- nuclear testing has been curtailed, the weap- lance of weapon systems and the associated ons in the stockpile are aging, and downsized measurement of the effects of aging on the fabrication facilities are being tightly inte- weapons in the stockpile. grated and focused as much on maintaining capability as on delivering small numbers of new components.

A qualitative Understanding Materials Aging representation of the is Key for Early Warning of Component connection between Performance changes in atomic Stockpile Issues structure, microstruc- ture, material properties, and component perfor- Material mance. The onset of Properties potential aging effects in plutonium is included along the Microstructure time axis. The goal is to identify the signatures of aging at the earliest possible ∆t time. This require- Atomic ment has driven the void swelling program to atomic Structure and nanoscale phase stability scientific

Cumulative Change He bubble formation? investigations. surface corrosion He ingrowth Time

Nuclear Materials Technology/Los Alamos National Laboratory 9 Actinide Research Quarterly

Stockpile Surveillance Plutonium Aging The Stockpile Surveillance Program Detecting and predicting age-induced ensures that the stockpile is free of defects that changes in nuclear materials are perhaps the may affect performance, safety, or reliability. most challenging and technically engaging The surveillance program has two elements: aspects of Science-Based Stockpile the Stockpile Evaluation Program and the Stewardship. Indeed, “science-based” arises Enhanced Surveillance Campaign. principally from this need, as opposed to a The first element, stockpile evaluation, “production-based” alternative or the provides examinations and assessments of “test-based” strategy used in years past. Analy- war-reserve stockpile weapons and components. sis, prediction, and mitigation of aging effects The second element, enhanced surveillance, are key to ensuring long-term functionality. provides the means to strengthen the However, changes in weapon performance Stockpile Evaluation Program to meet the as a result of aging represent the end in a series challenges of maintaining an aging stockpile of events that began years or decades earlier. in an era of no nuclear testing. Enhanced Changes occur first in the fundamental (or surveillance also provides lifetime assessments atomic-scale) properties of the materials within and predictions for Stockpile Life Extension the weapon—properties such as composition, Program (SLEP) planning. crystal structure, and chemical potential. The goal of the Enhanced Surveillance Changes are later found in the applied behav- Campaign is to protect the health of the ior of these materials—behaviors such as stockpile by screening weapons systems for density, compressibility, strength, and chemical manufacturing and aging defects to identify reaction rates. units that need to be refurbished. It also will be Only when the applied properties have used to predict material and component aging sufficiently changed can we anticipate their rates as a basis for annual certification, refur- impact on weapon performance. Therefore, the bishment scope and timing, and nuclear needs of the stewardship program have driven weapon complex planning. Results of the our studies toward nanoscale scientific investi- work will be used to make improvements to gations. The essence of this approach can be the basic surveillance program. seen in the illustration on page 9, where Because nuclear weapons will be retained changes at the atomic scale precede changes at in the stockpile for lifetimes beyond our expe- the microscopic or macroscopic scale, which rience, the DOE needs to be able to determine lead to changes in material properties, and when stockpile systems must be refurbished or ultimately, in device performance. reconditioned. If new refurbishment capability Analyzing, predicting, and mitigating is needed, the DOE needs to know when these aging effects in pits, specifically plutonium capabilities must be operational and what the pits, are key to ensuring long-term safety and required capacity should be, if the capacity for reliability in the primary stage of nuclear existing facilities is adequate, and when poten- weapons. We are studying the many changes tial refurbishment for the various stockpile that result from aging, including engineering systems must be scheduled. and physics performance characteristics such The DOE also needs to have a basis on as equation of state, spall and ejecta formation, which to characterize the functional reliability strength, density, geometry, corrosion resis- of aged components, which is part of the tance, and nuclear reactivity. annual assessment process.

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Our understanding of plutonium aging is The Enhanced Surveillance Campaign complicated by the fact that plutonium dis- and the needs of the Science-Based Stockpile plays some of the most complex physical and Stewardship Program have supported the chemical properties of any element in the peri- development of new science and technology, odic table. Aging mechanisms that can cause including resonant ultrasound measurements changes in fundamental plutonium material of the plutonium modulus, X-ray absorption and mechanical properties include the spectroscopy and neutron-scattering measure- in-growth of decay products, uranium recoil ments of plutonium structure, microstructure damage and associated void formation, void and surface characterization, positron annihi- swelling, changes in density, phase stability lation spectroscopy, isochronal annealing concerns, changes in surface chemistry, and a studies of radiation damage, dynamic prop- variety of environmental changes, including erty measurements, and new theoretical thermal cycling. models of radiation damage effects. Developing advanced characterization These tools will be useful in making tools to measure changes in these properties stockpile life-extension decisions, will expand our nuclear materials knowledge determining when or if a Modern Pit base and form the basis for computational Manufacturing Facility will be built, and for models necessary for predictive assessment. the weapon systems’ annual certification to We have adopted a dual strategy of using the president. data obtained from the oldest available pits and validated accelerated aging experiments using plutonium-238-spiked alloys to charac- terize the physics, engineering, and materials properties of plutonium. Accelerated aging alloys can be qualified by comparing them with normal alloys and the oldest pits. Changes in key properties can be predicted by modeling anticipated aging effects, especially radiation damage within the plutonium lattice. Measurement of these key pit properties will be used to determine age- related changes and to validate models.

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Pit Disassembly and Conversion Address Contributors to this a ‘Clear and Present Danger’ project are: Timothy Nelson (NMT-15 group For five decades, the world’s superpowers A major part of the Laboratory’s pit leader), Steven sought to increase the number of weapons in disassembly and conversion responsibilities McKee (NMT-15 their nuclear stockpiles. With the end of the is the Advanced Recovery and Integrated deputy group leader), Cold War and the advent of strategic arms Extraction System (ARIES), a state-of-the art Chris James (U.S. reduction treaties and agreements, the United prototype glove-box line operated at the Pit Disassembly and States and Russia are committed to retiring TA-55 Plutonium Facility by NMT-15. Conversion project thousands of weapons from their stockpiles. The ARIES line converts plutonium into leader), Stan But peace poses a dilemma: What should be an unclassified form that can be stored in Zygmunt (U.S./ done with the hundreds of tons of weapons- sealed containers and examined by interna- Russian Conversion grade plutonium removed from these tional nuclear material inspectors. The project leader), dismantled weapons? technology has been demonstrated to mini- Douglas Wedman In 1994, the National Academy of Sciences, mize waste and reduce worker exposure. Data (ARIES project in the report “Management and Disposition of collected from ARIES is being used to help leader), and Excess Weapons Plutonium,” called the exist- design the PDCF at Savannah River. David Kolman ence of this excess material “a clear and ARIES incorporates a variety of basic (Pit Disassembly and present danger to national and international and applied research, and development and Conversion Research security.” The safe disposal of surplus plutonium demonstration activities, including gas-solid and Development is key to the U.S./Russia arms-reduction effort. kinetics, materials corrosion, glove-box and project leader) The heart of the disposition program is pit container decontamination, pit machining disassembly and conversion, which is led by operations, plutonium-conversion processes, Los Alamos. The technology includes disman- tritium removal from contaminated plutonium, tling pits, the core of nuclear weapons; actinide electrochemistry, and long-term converting the plutonium from pits into a storage packaging. form suitable for use as an actinide ceramic Evaluation techniques used at ARIES materials, mixed-oxide fuel; providing include nondestructive assay, classified-part technical support for the design of the Pit sanitization, and advanced separation. Disassembly and Conversion Facility (PDCF) The work requires expertise in a variety of at Savannah River, slated to open before 2010; disciplines, including materials science, engi- managing the Russian Federation pit disas- neering, chemistry, physics, robotics and A flow chart of the sembly and conversion; and supporting the automation, and software development. ARIES glove-box line. Russian Federation nuclear fuel activities. Housed in a sequential series of glove boxes, ARIES consists of five modules, each designed to carry out a specific function. Each module incorporates advanced technologies that increase operational efficiency. Hydride- The process begins when a pit is introduced Dehydride Plutonium Pit Disassembly Furnace Metal into the system. The pit enters the pit bisection Product module, where it is bisected by a tool that Assay works like a pipe cutter. The pit may also be disassembled using a lathe. However, unlike traditional lathes, the pit bisection tool and the Oxide advanced lathe operations produce minimal Conversion Plutonium waste chips. From here, the pit undergoes a Oxide Canning and plutonium removal and conversion process. O2 Decontamination

Incoming Plutonium Removal Pit Assay and Conversion

12 Nuclear Materials Technology/Los Alamos National Laboratory 1st quarter 2001

To convert plutonium into an oxide ARIES has been form—the preferred product form for mixed- supported since 1995 oxide fuel (MOX)—the plutonium from the pit by the DOE Office of is oxidized in the direct metal oxidation Fissile Materials (DMO) furnace. In some pits, the plutonium Disposition, now may be removed by a reaction with hydrogen, known as NN-60 in which forms plutonium hydride powder. The the National Nuclear powder is thermally treated to form a metal Security Administra- puck that releases the small amount of hydro- tion. It was dedicated gen for reaction with more plutonium. To con- in September 1998. vert plutonium metal to oxide, the puck also The ARIES line then can be processed through the DMO furnace. went through a series Researchers currently are investigating other of “hot” tests and oxide conversion processes, including one completed its first that involves a hydride/nitride process integrated demonstra- and oxidation. tion, a three-month production-type A Fanuc robot Once the plutonium has been converted run that included seven pit types, in positions a welded into either an oxide or a metal, it is packaged September 1999. ARIES material can for leak testing before to meet Department of Energy (DOE) long- Since its first integrated demonstration, the decontamination. This term storage criteria. This packaging involves ARIES line has been upgraded to allow for an fully automated system three containers, two of which are hermetically increase in the size of the container. This reduces worker sealed and leak-checked. Before the first her- change required adjustments to the nonde- exposure during the metically sealed container can be removed structive assay instruments and robot, electro- packaging of plutonium from the glove-box line, researchers electrolyti- lytic decontamination fixture, and inner and oxide. The system is cally clean the surface using a process similar outer container welding station. undergoing extensive to electropolishing. Other upgrades performed since 1999 preinstallation testing at An electrolyte that consists of a sodium include the development of a pit disassembly TA-46 and should be sulfate and water solution uses electricity to lathe, a process control system for the lathe, operational within the induce a chemical reaction that removes a uni- and a process-control system for the TA-55 Plutonium Facility by the end of form layer of material and any contaminants hydride/dehydride process. December. on the cans. This module minimizes waste by ARIES is being readied for a second recycling the electrolyte. integrated demonstration later this year. After After the metal or oxide is packaged, a this demonstration, researchers will install a series of robotically operated nondestructive second set of upgrades that includes a fully assay instruments confirms the quantity of automated packaging line, developed with plutonium in each package. These measure- Sandia National Laboratories; a part sanitiza- ments are important for nuclear security and tion process; a uranium cleaning and burning safeguards; similar techniques will be used by glove-box line; two new direct-metal oxidation international inspectors to confirm the pack- furnaces; a laser-ablation inductively coupled age contents without having to open them. plasma mass spectrometer for elemental The pit bisector and hydride/nitride analysis; and uranium nondestructive processes were collaborative efforts between assay equipment. Los Alamos and Lawrence Livermore National The upgrades also will include Laboratory. Currently, NMT-15 and NIS-5 are modifications to the special recovery line working with the Russian Federation to that removes tritium contamination from develop a similar nondestructive assay plutonium and adapting robotics for system for use in Russia. pit handling in conjunction with lathe operations.

Nuclear Materials Technology/Los Alamos National Laboratory 13 Actinide Research Quarterly Publications and Invited Talks

Attention, authors: Have you published a paper, book or book Bailey, G., E.A. Bluhm, J.L. Lyman, R.E. Mason, Mitchell, J.N., R.A. Pereyra, W.B. Hutchinson, chapter, or given M.T. Paffett, G.P. Polansky, G.D. Roberson, L.A. Morales, T.G. Zocco, and J.E. Vorthman, aninvited talk? Please M.P. Sherman, K. Veirs, and L.A. Worl, “Gas “Microstructural and Phase Characterization of Generation from Actinide Oxide Materials,” Cimmaron Test Material,” Los Alamos National send the particulars to Los Alamos National Laboratory report LA-13781- Laboratory report LA-13779-MS (January 2001). [email protected] and MS (December 2000). we’ll publish your cita- Reimus, M.A.H., and G.L. Silver, “Metals for the tion in a future issue Balkey, J.J., and R.E. Wieneke, “Transuranic Waste Containment of Nitric Acid Solutions of Plutonium- of ARQ. Management at Los Alamos National Laboratory,” 238,” J. Radioanal. Nucl. Chem. 242, 265-277 (1999). Nuclear Energy—Journal of the British Nuclear Energy Society 40 (1), 53-58 (2001). Ronquillo, R., “Preparation of a Glovebox for Cast- ing Plutonium Enriched with 238Pu,” in Abstracts of Jordan, H., “Analysis of Aircraft Crash Accident of Papers of the American Chemical Society 220, Pt.1, WETF,” Los Alamos National Laboratory report p. U210 (August 2000). LA-13799-MS (January 2001). Scoates, J.S., and J.N. Mitchell, “The Evolution of Jordan, H., “Seismic Performance Requirements on Troctolitic and High Al Basaltic Magmas in Protero- WETF,” Los Alamos National Laboratory report zoic Anorthosite Plutonic Suites and Implications for LA-13798-MS (January 2001). the Voisey’s Bay Massive Ni-Cu Sulfide Deposit, Econ. Geol. 95, 677-701 (2000). Martinez, B.T., “WITS — Waste Data Collection with Our Palms at Our Fingertips,” Los Alamos National Sheldon, R.I., G.H. Rinehart, S. Krishnan, and Laboratory document LA-UR-00-4028, in Proceedings P.C. Nordine, “The Optical Properties of Liquid of Spectrum 2000, International Conference on Cerium at 632.8 nm,” Mater. Sci. Eng. B 79, 113-122 Nuclear and Hazardous Waste Managment, (2001). CD-ROM (August 2000). Silver, G.L., “Pu(IV) Polymer Formation,” Los Miller, D.A., W.R. Thissell, D. MacDougall, and Alamos National Laboratory document LA-UR-00- J.J. Balkey, “Effect of Repeated Compressive 2506 (to be published in J. Radioanal. Nucl. Chem.). Dynamic Loading on the Stress-Induced Martensitic Transformation in Niti Shape Memory Alloys,” Los Wong, A.S., “Chemical Analysis of Plutonium-238 Alamos National Laboratory document LA-UR-00- for Space Applications,” in Space Technology and 384 (June 2000). Applications International Forum 2001 552, (February 2001).

Fellows Prize: David Clark (NMT-DO) is one of three technical staff members named 2000 Lab Fellows Prize winners. The Fellows Prize recognizes high-quality published research in science and Newsmakers engineering having a significant impact on a particular field or discipline. Clark was recognized for his outstanding contributions to the understanding of the molecular behavior and solution chemistry of actinide ions. Recipients of the award received a $3,000 check and a certificate from Director John Browne.

High school talk: As part of NMT’s outreach activities, Derek Gordon (NMT-14) recently gave a talk on nuclear energy to juniors at St. Michael’s High School in Santa Fe. His talk covered the Los Alamos ARIES program and the current U.S.–Russia collaborations on weapons dismantlement and the use of mixed-oxide fuels.

Pollution Prevention Award: A team from NMT-9 has earned a 2000 Pollution Prevention Award from the Lab’s Environmental Stewardship office for its development of an improved process to isolate plutonium oxide from scraped fuel. Plutonium-238 is used in heat sources and heat units for NASA deep-space missions. The innovation has cut the recovery waste stream by more than 75 percent and is helping the Lab move closer to meeting the DOE’s 2005 pollution prevention goals. Team members include. Gerald Allethauser, Jason Brock, Amy Ecclesine, Paul Moniz, Jonetta Nixon, Maria Pansoy-Hjelvik, Kevin Ramsey, Mary Ann Reimus, Mary Remerowski, and Gary Silver.

14 Nuclear Materials Technology/Los Alamos National Laboratory 1st quarter 2001

New Energy Secretary Addresses Los Alamos Employees

Editor's note: The following excerpts are from reliability of weapons without testing them, Energy Secretary Spencer Abraham's April 19 and yet, that’s precisely what we are doing all-hands meeting at Los Alamos. now. It’s really an astonishing technical and scientific enterprise, and it calls for the same … Los Alamos has a history that is a qualities of genius that this facility has un- special one and, perhaps, can best be described leashed throughout its history. as humbling to all of us. I’m sure when you think about the people in whose footsteps you At the same time, our mission have followed—the Oppenheimers, the Tellers, today is broader and more difficult and others, it’s on one hand inspiring and on because we have added counter- the other hand kind of overwhelming. I sus- proliferation and nonproliferation to pect that’s a daunting challenge, but I believe our traditional missions of deterrents that the people working here today are every as we attempt to reduce a host of bit as able and talented as those who preceded threats to our nation. I can’t think of you, and we look forward to accomplishing anything more compelling in terms great things together. of a mission or one that calls upon a greater degree of technical excellence You look at what has happened and what than those that we confront today. Los Alamos has been able to contribute to mankind, and in my judgment those benefits … I consider nothing that I have are incalculable, whether it was victory for the in terms of responsibility more Allies in the second world war or it was vic- important then the duty that I share tory for the West in the Cold War. But for you, with the secretary of defense to cer- breakthrough science would take place in tify to the president, along with our another country. But for you, supercomputing Lab directors, the fitness of our would be a technology for us to purchase stockpile. … What I’ve tried to con- abroad, not develop and refine here at home. vey to the White House and to the photo by LeRoy N. Sanchez And, but for the people who’ve worked at this other policymakers is the significant facility, we would now be living in the 55th importance of the stockpile stewardship pro- Energy Secretary year of the Cold War, instead of enjoying the cess that we are so integrally tied up with here Spencer Abraham. eleventh year of the peace dividend. in the department and the NNSA. In an era where we don’t test, as you know better than … But we don’t live in a totally peaceful anybody does, the work that we do to certify world, even though the Cold War may be over. is the most critical component in many It’s still a dangerous place. Our stockpile, the respects of America’s national security weapons that are built and maintained, is a that we have. result of no small measure of the work that’s here, remain the vital factor that ensures the Our deterrent capability is only premised stability of America’s national security in a on the belief on the part of the rest of the changing and dangerous world. As much as world that the weapons we have will work in we admire the work of the scientists who a reliable fashion. If we don’t test those brought us the first weapons—Fat Man and weapons, but in fact work through the science- Little Boy—it is clear that your scientific con- based stockpile program to try to ensure that tributions are no less important than theirs. reliability, then the work you’re doing is prob- ably as central as anything could possibly be … Gen. Gordon has pointed out to me that to the long-range security of this country. our labs are today again exploring territory that is virtually as uncharted and complex as It is my hope and my plan to work that which was opened up by the scientists of together with John Gordon to make sure that the Manhattan Project. No one in history, as sufficient resources are provided to be able to far as I know, has ever tried to confirm the do that work in the fullest sense. …

Nuclear Materials Technology/Los Alamos National Laboratory 15 Actinide Research Quarterly

Newsmakers Department of Energy Secretary Spencer Abraham recently made his first visit to Los Alamos since becoming energy secretary. One of his stops was TA-55, where he was given a les- son on how to work in a glove box and an overview of the Laboratory’s plutonium pit fabrica- tion program. He also was trained and performed a step in the pit fabrication and certification process. “What the trip today has so far done is reinforce my pride in and confidence in the people who work in our labs,” Abraham said. “I wanted to come here early to just reinforce my already-held opinion of the quality of work done here and to try to assess some of the needs so I could be a more effective participant in the [national security] reviews.” Abraham later told reporters he is working closely with NNSA Administrator Gen. John Gordon to identify chal- lenges the DOE faces and how it can work with the National Security Council, Department of Defense, and other agencies. One of those challenges, he said, is long-range strategic decisions as to the U.S.’s nuclear forces, the nation’s stockpile of nuclear weapons in relation to nonprolif- eration, and counter- proliferation programs. Gen. Gordon accom- panied Abraham on his April 19 visit.

See page 15 for excerpts from Abraham’s

all-hands meeting. photo by LeRoy N. Sanchez

Nuclear Materials Technology Division Los Alamos Mail Stop E500 NATIONAL LABORATORY Los Alamos National Laboratory LALP-01-121 Los Alamos, New Mexico 87545 Phone (505) 667-2556/Fax (505) 667-7966

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The Actinide Research Quarterly highlights recent achievements and ongoing programs of the Nuclear Materials Technology (NMT) Division. We welcome your suggestions and contributions. If you have comments, suggestions, or contributions, you may contact us by phone, mail, or e-mail ([email protected]). ARQ also can be read on the World Wide Web at: http://www.lanl.gov/Internal/divisions/NMT/nmtdo/AQarchive/AQindex/ AQindex.html.

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16 Nuclear Materials Technology/Los Alamos National Laboratory