Plutonium and Neptunium Conversion Using Modified Direct Denitration L. K. Felker Nuclear Science and Technology Division Oak Ridge National Laboratory Actinide and Fission Product Partitioning and Transmutation Eighth Information Exchange Meeting Las Vegas, Nevada November 9-11, 2004

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 2 Development of Direct Denitration  Initial development work on uranyl nitrate conversion to uranium oxide  Direct denitration produced a low-surface-area glassy product  Product would require further processing to obtain desired ceramic properties  Ceramic properties should be comparable to oxide obtain by ammonium diuranate (ADU) process  Incorporation of an additive to the uranyl nitrate solution produced oxide with desired ceramic properties; thus named the Modified Direct Denitration (MDD) process

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 3 Why Direct Denitration?  Spent fuel processing produces a number of purified product streams  Typical product is in nitric acid solution  Conversion to solid form needed for recycle, storage, or disposal  Direct conversion to oxide with proper ceramic properties for recycle ideal Reactors Chemical Processing Fuel Fabrication

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 4 Scope of MDD Study  Establish capability to prepare oxides by MDD method on a laboratory scale  Convert Pu/Np product fractions from nitrate solutions to oxides via the MDD method  Co-convert U/Pu and other uranium mixtures to oxides via the MDD method  Determine ceramic properties of the oxide products for comparison with fuel fabrication specifications

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 5 Schematic of MDD Test Equipment

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 6 Photograph of MDD Test Equipment

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 7 Cerium Nitrate Testing  Established basic parameters: - Furnace temperature - Incline angle - Tube rotation rate - Air purge - Vacuum  Established operational parameters - Feed concentration - Feed addition rate - Material balances - Condensate carryover - Condensate recycle

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 8 Cerium Testing Results and Observations  A slight incline angle resulted in stable temperature, steady off-gas rate, and constant product rate  Concentrated feed reduced evaporative loading of the furnace  Air purge adjusted to move vapors but limit entrainment  Material balances complicated by accumulation of oxide inside furnace tube  Good acid balance between feed and condensate  Cerium oxide product was agglomerated but easily broken by sieving  Average particle size in the range of 200 μm  Tap density of cerium oxide measured to be ~0.7 g/cm 3  Cerium oxide in the condensate removed by filtration  Acidic condensate recycle was investigated and proved successful

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 9 Plutonium Conversion Results and Observations  Feed contained lower than desired Pu conc and higher H + conc  Dilute feed resulted in higher off-gas rate and increased entrainment  Pu loss to the condensate was ~1%  With neutralization and filtration, Pu in condensate reduced by a factor of ~300  Pu oxide product was free- flowing powder with tap density of ~3 g/cm 3

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 10 Future Direction  Test Pu nitrate conversion at higher Pu concentration  Investigate the co-conversion of U/Pu solutions  Investigate the co-conversion of U/Pu/minor actinide solutions

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 11 Acknowledgements Technical Direction: Emory Collins Equipment Design: Ray Vedder MDD Operation: Ray Vedder and Ron Brunson Funding: DOE Office of Nuclear Energy through AFCI Separations Jim Laidler, National Technical Director