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