plutonium and neptunium conversion using modified direct denitration l. k. felker nuclear science...
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Plutonium and Neptunium Conversion Using Modified Direct Denitration
L. K. FelkerNuclear Science and Technology DivisionOak Ridge National Laboratory
Actinide and Fission Product Partitioning and TransmutationEighth Information Exchange MeetingLas Vegas, NevadaNovember 9-11, 2004
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Schematic of MDD Test Equipment
S c r u b b e r
C o n d e n s e r
P u m pC o n d e n s a t eC o l l e c t i o n
F e e dT a n k
O f f - g a s
R o t a r y K i l n F u r n a c e
A i r p u r g e
O x i d e P r o d u c t
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Photograph of MDD Test Equipment
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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/cm3
Cerium oxide in the condensate removed by filtration
Acidic condensate recycle was investigated and proved successful
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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/cm3
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Acknowledgements
Technical Direction: Emory Collins
Equipment Design: Ray Vedder
MDD Operation: Ray Vedder and Ron Brunson
Funding: DOE Office of Nuclear Energy through AFCI SeparationsJim Laidler, National Technical Director
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