Depleted Uranium Hexafluoride (DUF 6 ) Storage, Conversion, and Management in the U.S.

1. Depleted Uranium Hexafluoride (DUF6) Storage, Conversion, and Management in the U.S. Gerald G. Boyd Presented at the Russian-American Workshop on Management of Depleted Uranium Assistant Manager for Environmental Management U.S. Department of Energy Oak Ridge Operations December 9–10, 2002 Moscow, Russia

2. Depleted Uranium (DU) Is a Legacy of Uranium Enrichment

3. Worldwide DU Inventory* Inventory (MTU) Storage form Enricher United States France (COGEMA and Eurodif) Urencoa United Kingdom (BNFL) Russia Japan Republic of Korea China 480,000 190,000 16,000 30,000 460,000 10,000 200 2,000 UF6 U3O8 UF6 UF6 UF6 UF6 UF6 UF6 aUrenco operates plants in Germany, the Netherlands, and the United Kingdom. *Source: Management of Depleted Uranium, OECD Nuclear Energy Agency and International Atomic Energy Agency, report number ISBN 92-64-19525-4, 2001.

4. DOE Inventory of DUF6 TotalDUF6(metric tons) Total Cylinders Location Paducah, Kentucky Portsmouth, Ohio Oak Ridge, Tennessee Total 36,910 16,041 4,683 57,634 450,000 198,000 56,000 704,000 Location of DUF6 storage sites

5. The U.S. DUF6 Management Program Involves Three Primary Activities • Cylinder storage, surveillance, and maintenance • Conversion of DUF6 to a more stable chemical form for use or disposal • Development of beneficial uses of DU

6. 1. Cylinder Storage, Surveillance, and Maintenance • Inspect cylinders for degradation • Restack cylinders to improve drainage and to allow thorough inspections • Repaint cylinders to arrest corrosion • Build new cylinder yards Cylinder Management 57,634cylinders 704,000 MTof DUF6 The cylinder management program is responsible for safely storing DOE’s DUF6 inventory at Paducah, Portsmouth, and East Tennessee Technology Park sites until the DUF6 is used or disposed of

7. How DUF6 Is Stored • DUF6 is typically stored in carbon steel cylinders that hold 9–12 metric tons of DUF6 • The 14-ton-capacity cylinders (12 metric tons) are 12 ft (3.7 m) long by 4 ft (1.2 m) in diameter • Cylinders are initially filled to 95% capacity with liquid DUF6, which is allowed to cool over several days. As the liquid cools, it forms a solid that fills approximately 60% of the internal cylinder volume

8. DUF6 Storage in the U.S. Approximately 704,000 metric tons of DUF6 is stored in ~57,600 steel cylinders at three sites in the U.S. DUF6 is stored horizontally in carbon steel cylinders that hold 9–12 metric tons of DUF6. The cylinders are stored in large outdoor areas called “cylinder yards” A program of regular surveillance and maintenance activities ensures the safety of continued cylinder storage

9. Deteriorating Storage Conditions Cause Environmental and Safety Concerns The advanced age of some cylinders and the way in which the cylinders were stored have created a potential environmental and safety hazard Concerns include • Breaches • Rust and corrosion • Yard conditions • Water damage • Ground contact While DUF6 does not present as significant a radiological hazard as other radioactive materials, it is a potential chemical hazard if not properly managed

10. DUF6 Cylinder Leakage A small number of cylinders have leaked over the last 40 years; leaking cylinders are repaired, and material that leaks onto the ground is removed Chemical Reactions During Leakage If a cylinder leak (breach) occurs and the DUF6 is exposed to water vapor in the air, uranyl fluoride (UO2F2) and hydrogen fluoride (HF) are formed. The uranyl fluoride is a solid that plugs the leak, limiting further escape of DUF6. Release of the hydrogen fluoride gas to the atmosphere is also slowed by the plug formation Breach (leak) in a DUF6 cylinder

11. Surveillance and Maintenance Program Activities The day-to-day management of the DUF6 cylinders includes actions designed to cost-effectively improve their storage conditions • Performing regular inspections and general maintenance of cylinders and storage yards • Restacking and respacing the cylinders to improve drainage and to allow for more thorough inspections • Repainting ends of skirted cylinders and repainting cylinder bodies as needed to arrest corrosion • Constructing new concrete cylinder storage yards and reconditioning existing yards from gravel to concrete to improve storage conditions

12. 2. DUF6 Conversion Full cylinders go to conversion plants at Portsmouth and Paducah DU product, aqueous HF, empty cylinders Government-owned and contractor-operated facilities will convert DOE’s DUF6 inventory located at the storage sites to some other stable chemical form acceptable for transportation, beneficial use/reuse, and/or disposal • DUF6 cylinder receipt, inspection, and processing • Cylinder preparation for DUF6 vaporization • Conversion to uranium oxide using Framatome’s dry conversion process • Product storage limited to less than 6 months • Transportation and disposal of uranium oxide • Marketing of HF

13. Conversion of DUF6 to a More Stable Form DOE has recently awarded a $558M contract to convert and dispose of 704,000 metric tons of DUF6 • Contract awarded August 29, 2002, to Uranium Disposition Services, LLC • Framatome ANP • Duratek Federal Services • Burns and Roe • Contract is for • Design, construction, and 5-year operation of two facilities located at the gaseous diffusion plants at Portsmouth, OH, and Paducah, KY • Surveillance and maintenance of cylinder inventory • Shipment of UF6 cylinders from Oak Ridge, TN, to Portsmouth, OH • DU product (DU3O8) sent for disposal, if no reuse is found • Construction to start by July 31, 2004 • Contract provides incentives for reuse of DU

14. 3. Development of Beneficial Uses of DU Depleted Uranium Uses Research and Development Program MarketableProducts Develop beneficial uses of DUF6 conversion plant products DU is a potentially valuable energy resource Goal: Reduce costs by avoiding transportation and disposal costs • Fundamental research • Prototype fabrication and demonstration of near- commercial technology • Focus on DOE system-wide uses and cost reductions • Industry/university cooperation • International collaboration • Reduction of regulatory and institutional barriers

15. Beneficial DU Uses That Consume the Inventory, But Have Low Market Value, $/t DU • Geologic repository DU surrounding the wastepackage provides a chemical barrier to spent nuclear fuel (SNF) • SNF and high-level-waste casks New DU concrete and steel cermet materials enable smaller, lighter-weight casks

16. Beneficial, Innovative Material Uses That Have High Intrinsic Value, $/t DU (Royalties from licensing these materials will lower overall DU disposition costs) • Catalysts • Semiconductors • Electrodes for hydrogen production • Batteries • Fuel cells • Others Solar Panel Installed at ORNL Roof Test Facility

17. Development of Beneficial Uses of DU A Depleted Uranium Uses Research and Development Program has been initiated to explore beneficial uses of DU and other materials resulting from conversion of DUF6 DOE is committed to exploring the safe, beneficial use of DU and other materials (e.g., fluorine and empty carbon steel cylinders) resulting from conversion of DUF6 for the purposes of resource conservation and cost savings. Accordingly, a Depleted Uranium Uses Research and Development Program has been initiated. This program explores the risks and benefits of many DU uses

18. Back-up Slides

19. Where DUF6 Is Stored in the U.S. The UF6 at the three sites is stored in cylinders in large outdoor areas called "cylinder yards" at the three gaseous diffusion plants where it was produced DUF6 cylinder yards DUF6 is stored at the gaseous diffusion plant locations

20. Routine Surveillance and Maintenance Program Activities A cylinder yard worker vacuums debris from the skirt of a DUF6 storage cylinder Measuring cylinder wall thickness The skirted ends of DUF6 cylinders after being painted to arrest corrosion