CONP-9110117- DE92 005283 Second international Conference Uranium Hexafluoride Handling Compiled by Conference Staff William G. Pollard Auditorium Oak Ridge, Tennessee October 29-31,1991 Prepared by the Oak Ridge National Laboratory managed by Martin Marietta Energy Systems Inc. for the U.S. DEPARTMENT OF ENERGY under Contract No. DE-AC05-84OR21400 FOREWORD The United States Department of Energy, Oak Ridge Field Office, and Martin Marietta Energy Systems, Inc., arc co-sponsonng this Second International Conference on Uranium Hexafluoride Handling. The conference is offered as a forum for the exchange of information and concepts regarding the technical and regulatory issues and the safety aspects which relate to the handling of uranium hexafluoride. Through the papers presented here, we attempt not only to share technological advances and lessons learned, but also to demonstrate thai we are concerned about the health and safety of our workers and the public, and are good stewards of the environment in which we all work and live. Increasing levels of environmental awareness and concern on the part of the general public, as well as increasingly stringent governmental controls and regulations, place every greater emphasis on the need for safety in handling and processing of uranium hexafluoridc in all phases of the nuclear fuel cycle. The increasingly restrictive public climate in which the industry operates requires that we maintain a continuing scrutiny of our operations, procedures, and attitudes, and that we demonstrate continuing improvement in all aspects of safe handling of uranium hexafluoride. The present conference is a step in that direction. These proceedings are a compilation of the work of many experts in that phase of world-wide industry which comprises the nuclear fuel cycle. Their experience spans the entire range over which uranium hexafluoridc is involved in the fuel cycle, from the production of UF6 from the naturally-occurring oxide to its re-convcrsion to oxide for reactor fuels. The papers furnish insights into the chemical, physical, and nuclear properties of uranium hcxafluoridc as they influence its transport, storage, and the design and operation of plant-scale facilities for production, processing, and conversion to oxide. The papers demonstrate, in an industry often cued for its excellent safety record, continuing efforts to further improve safety in all areas of handling uranium hexafluoride. C. R. Barlow, Co-Chairman Martin Marietta Energy Systems, Inc. J. R. Russell, Co-Chairman DOE Field Office Conference Staff Contents Laying the Foundation: Properties of UFf Aspects of Uranium Chemistry Pertaining to UF, Cylinder Handling R.L.Rittcr.E.i. Barber 3 Chemical Aspects of Cylinder Corrosion and a Scenario for Hole Development E. J. Barber 9 Health Physics Considerations in UF, Handling J. C. Bailey 21 Uranium Facilities: An International Overview Urcnco's Experience of UFt Handling F. Saclmans, C. Scane J. Christofzik, 29 18 Years Experience on UF4 Handling at Japanese Nuclear Fuel manufacturer H. Fujinaga, N. Yamazaki N. Takebe 37 Safety Provisions for UF, Handling in the Design of a New UF, Conversion Plant S. P. Bannister 45 Implementation of Conduct of Operations at Paducah Uranium Hexafluoride (UFt) Sampling and Transfer Facility S. R. Pernod 53 Uranium Facilities: Improvements in Safety and Operations Uranium Hexafluoride: A Manual of Good Practice, ORO-651 Revision 6 R. H. Dyer 55 UFS Overfilling Prevention at Eurodif Production Georges Besse Plant J. M. Reneaud 59 Reuse of Activated Alumina J. E. Hobcnsack 73 Operations: Safety in Cylinder Handling Alternative Method of Retesting UF( Cylinders R. Christ 77 Temporary Patching of Damaged UF6 Cylinders A. L. Cardenas 79 Uranium Hexafluoride—Liquid Thermal Expansion, Elusive Eutcctic with Hydrogen Fluoride, and Very First Production Using Chlorine Trifluoride G. P. Rutledge 85 UF4 Cylinder Lifting Equipment Enhancements J. M. Hortel 93 Operations: Analyzing for Safety Autoclave Nuclear Criticality Safety Analysis D. M. D'Aquila, Robert W. Tayloc, Jr. 99 A Probabilistic Safety Analysis of UF4 Handling at the Portsmouth Gaseous Diffusion Plant G. J. Boyd, S. R. Lewis, R. L. Summit! 107 A Nuclear Criticality Safety Assessment of the Loss of Moderation Control in 2 1/2- and 10-Ton Cylinders Containing Enriched UF6 R. L. Newvahner, W. A. Pryor 115 Cylinders: Storage and Maintenance The Ultimate Disposition of Depleted Uranium Hexafluoride T. R. Lemons 123 .An Update on Corrosion Monitoring in Cylinder Storage Yards H. M. Henson 131 UFS Cylinder Inspections at PGDP G. W. Lamb, W. N. Whinnery 135 VI Radiation Dose Rates from UF, Cylinders P. J. Friend 137 Radiation Levels on Empty Cylinders Containing Heel Material C. W. Shocklcy 145 Cylinders: Regulations and Testing The Legal Status of UF(-Cylinder Testing and Licensing in Gennany (and Europe) K.E.Wieser,A.Tictze 149 Fire Testing of Bare Uranium Hexafluoride Cylinders W.A.Pryor 159 Modelling of the Thermal Behaviour of 48-Inch Cylinders D. C. Clayton, T. J. Hayes, E. Livesey, J. Lomas, M. Price 163 High Temperature Experiments on a 4-Ton UF, Container—TENERDFE Program C. Casselman, B. Durct, J. M. Seiler, C. Ringot, P. Warnicz 169 Poster Session UF, Cylinder Fire Test S. H. Park 179 Development of a UF6 Cylinder Transient Heat Transfer/Stress Analysis Model W.R. Williams 181 Cyl nder Monitoring Program J. H. Alderson 183 Reaction of Aluminum with Uranium Fluorides and Oxyfluorides J. M. Leitnaker, R. W. Nichols, B.S. Lankford 185 Fire Testing of Bare Uranium Hexafiucride Cylinders W. A. Pryor 195 VII Metamoqphosis: Phases of UFt R. H. Dyer 197 Fire Exposure to Empiy 30B Cylinders K.T.Ziehlke !99 Conceptual Design for PSP Mounting Bracket G. H. Ransom. R. C. Stein 203 Refurbishment and Modification of Existing Protective Shipping Packages (for 30-inch UF4 Cylinders) Per USDOT Specification No.USA-DOT-21PF-lA W. R. Housholder 207 UF6 Tiedowns for Truck Transport—Right Way/Wrong Way F. W. Stout, Jr. 213 Implementation of Conduct of Operations at Paducah Uranium Hexafluoride (UF4) Sampling and Transfer Facililty S. R. Penrod 223 Cylinders: Valve Studies One-Inch Valve for UF4 Containers Packing-Nut Failure: Cause of the Problem and Suggesetcd Solutions T. A. Barlow 227 Cylinder Valve Packing Nut Studies S. C. Blue 229 Testing of One-Inch UF6 Cylinder Valves Under Simulated Fire Conditions P. G. Elliott 235 Transportation: Operations and New Standards Overseas Shipments of 48Y Cylinders R. T. Tanaka. A. S. Furlan 245 The Design,Fabrication and Maintenance of Semi-Trailers Employed in the Highway Transport of Weight-Concentrated Radioactive Loads D. S. Huffman 253 Quality Assurance and the Transport of UFt N. L. Ravcnscroft 259 vni Lessons Learned UFB Pressure Excursions During Cylinder Heating P. G. Brown 265 Incidents of Chemical Reactions in Cell Equipment N. M. Baldwin, C. R. Barlow 271 Breached Cylinder Incidcni at the Portsmouth Gaseous Diffusion Plant R. A. Boelens 277 Investigation of Breached Depleted UF6 Cylinders ~ J. H. DeVan 279 Cracked Lifting Lug Welds on Ten-Ton UF6 Cylinders R. E. Doming II 289 Acknowledgments 295 IX Laying the Foundation: Properties of UF6 ASPECTS OF URANIUM CHEMISTRY PERTAINING TO UF4 CYLINDER HANDLING R. L. Ritter and E. J. Barber Uranium Enrichment Organization Martin Marietta Energy Systems, Inc. Oak Ridge, Tennessee USA ABSTRACT 100 000 er CRITICAL POINT 330 2°C •lib ami Under normal conditions, the bulk of UF6 in storage cylinders will be in the solid state with an 10000 overpressure of gaseous UFS well below one atmosphere. Corrosion of the interior of the - SOLID cylinder will be very slow, with formation of a TRIPU POINT M QJ°C small amount of reduced fluoride, probably U:F9. I 497 »lm SUBLIMATION POINT 6f)<»C The UOj-HF-H;O phase diagram indicates that I 00 dm reaction of any inlcaking water vapor with the VAPOtt solid UF6 will generate (he solid material [H,O]:(U(OH)4F4) in equilibrium with an aqueous HF solution containing only small amounts of uranium. The corrosion of the steel cylinder by I I I I I I I I I I I I these materials may be enhanced over that 100 ISO 200 260 TEMPERATURE. °C observed with gaseous anhydrous UF6. Fig. 1. UFt phase diagram. NOMENCLATURE The phase diagram for pure UF6, in which the R Rate of penetration of steel by UF6 logarithm of the pressure is shown as a corrosion, mil/day function of temperature, is presented in Fig. 1; the data shown are those of Oliver et al.(2) T Temperature, K Several important points can be made from this diagram. At room temperature, UF6 is a solid which exhibits a small but significant vapor INTRODUCTION pressure, about 80 torr. The sublimation temperature (the temperature at which the vapor Uranium hexafluoride (UF6) is employed in many pressure of the solid is one atmosphere) is phases of the nuclear industry. Therefore, we S6A°C. The relatively high vapor pressure of should be familiar with any physical or chemical UF6 makes it by far the most volatile uranium- properties which affect safe use and storage of containing compound known, which is, of this material. The basic physical and chemical course, the principle reason that UF6 is properties of UF6 were summarized by Baiber(l) employed in most of (he world's uranium in a paper presented at this conference three years isolopic enrichment plants. At temperature and ago, so these will not be considered in detail in pressure conditions above those of the triple this paper. However, a few of the most important point, (the point at which soiid, liquid, and of these basic properties will be briefly discussed vspor can all coexist and which occurs for UF5 to serve as an introduction for the remaining at 64.02°C and 1.497 atmospheres), a liquid material to be presented.