Oxide Rocky Flats

An overview is presented of plutonium process chemistry at Rocky Flats and of research in progress to improve plutonium processing operations or to develop new processes. Both pyrochemical and aqueous methods are used to process plutonium metal scrap, oxide, and other residues. The pyrochemical processes currently in production include electrorefining, fluorination, hydriding, molten salt extraction, calcination, and reduction operations. Aqueous processing and waste treatment methods involve nitric acid dissolution, ion exchange, solvent extraction, and precipitation techniques. 

Dissolution. Plutonium is solubilized in nitric acid solutions at Rocky Flats. The feed material consists of oxide, metal and glass, dissolution heels, incinerator ash and sand, slag, and crucible from reduction operations. The residues are contacted with 12M HNO3 containing CaF2 or HF to hasten dissolution. Following dissolution, aluminum nitrate is added to these solutions to complex the excess fluoride ion. 

Results on the first four examples given in Table 17.10 are from the literature [10, 30-32]. The last two provide the results on Ceramicrete waste forms. The transuranic (TRU) combustion residue was obtained originally from Rocky Flats. It was fully calcined for safe transport to ANL. Therefore, all organics and combustibles were completely incinerated, and that step enhanced the Pu concentration. The U-Pu oxide mixture was a... 

Separations research at the Rocky Flats Plant (United States) has found ways to significantly improve Pu recovery from HNO waste streams by using extraction chromatography. Several extractants, including TBP (tribu-tylphosphate), TOPO (tri- -octylphosphine oxide), DHDECMP (dihexyl N,N-diethylcarbamoylmethylenephosphonate), and CMPO (octylphenyl-N,N-diisobutylcarbamoylmethylphosphine oxide) and their mixtures supported on Amberlite XAD4 and anion exchange resins (Dowex 1x4 and Amberlite IRA 938), were evaluated for their ability to remove low concentrations of plutonium from 7 M acid nitric [71-73],... 

Differences of 2% in keff have also been observed in analyzing the first set of bulk-oxide add-on experiments at Rocky Flats. For configuration IB described in report No. RFP-2868, KENO yielded a kgff of 1.016 O.OOS using the NITAWL data and a keff of 0.998 0.005 using the ROLAIDS data. 

Critical experiments, ptisored by the U.S. Nuclear Regulatory Commission, were performed at the Critical Mass Laboratory at Rockwell International s Rocky Flats Plant in Golden, Colorado to provide accurate crificality data for low-enriched damp uranium oxide (Uj0 ) systems. 

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