Curium recovery

Sill et al. [26] have discussed a spectrometric method for the determination of americium and other alpha-emitting nuclides, including curium and californium, in potassium fluoride-pyrosulfate extracts of soils. Sekine [27] used a-spectrometry to determine americium in soils with a chemical recovery of 60-70%. Joshi [28] and Livens et al. [29] have discussed methods for the determination of241 americium in soils. 

This collection of the state-of-the-art papers emphasizes the continuing importance of industrial-scale production, separation, and recovery of transplutonium elements. Americium (At. No. 95) and curium (At. No. 96) were first isolated in weighable amounts during and immediately after World War II. Berkelium and californium were isolated in 1958 and einsteinium in 1961. These five man-made elements, in each case, subsequently became available in increasing quantities. 

An initial experiment involving the treatment of small irradiated Pu/Al targets for the production of americium 243 and curium 244 was carried out in France in 1968 (2). The chemical process was based essentially on the use of a system comparable to the Talspeak system. After plutonium extraction by a 0.08 M trilaurylammonium nitrate solution in dodecane containing 3 vol % 2-octanol, the actinides (americium, curium) were coextracted with a fraction of the lanthanides by a 0.25 M HDEHP -dodecane solvent from an aqueous solution previously neutralized by A1(N0 ) x(0H)x and adjusted to 0.04 M DTPA. The actinides were selectively stripped by placing the organic phase in contact with an aqueous solution of the composition 3 M LiN0 -0.05 M DTPA. While this experiment achieved the recovery of 150 mg of americium 243 and 15 mg of curium 244 with good yields, the process presented a drawback due to the slow extraction of Al(III) which saturates the HDEHP. This process was therefore abandoned. 

A research and development program on the recovery and purification of potentially useful by-product actinides from the nuclear fuel cycle was carried out some years ago in the Federal Republic of Germany as part of the "Actinides Project" (PACT). In the course of this program, procedures for the recovery of neptunium, americium and curium isotopes from power reactor fuels, as well as procedures for the processing of irradiated targets of neptunium and americium to produce heat-source isotopes, have been developed. The history of the PACT Program has been reviewed previously (1). Most of the PACT activities were terminated towards the end of 1973, when it became evident that no major commercial market for the products in question was likely to develop. 

Ross, R. G. Wiggins, J. T. "Preparation of Curium-Americium Oxide Microspheres by Resin-Bead Loading", paper presented at Symposium on Industrial Scale Production-Separation-Recovery of Transplutonium Elements, 2nd Chem. Congr. North American Continent, Las Vegas, NV, 1980. 

Bigelow, J. E. Collins, E. D. King, L. J. "The "Cleanex" Process A Versatile Solvent Extraction Process for Recovery and Purification of Lanthanides, Americium, and Curium," Actinide Separations, ACS Symp. Series, No. 117, 1980, 147-155. 

Recovery of Americium—Curium From High-Activity Waste Concentrate by In-Canyon-Tank Precipitation as Oxalates... 

Modifications to this process can be made to effect recovery of neptunium, americium, curium, californium, strontium, cesium, technetium, and other nuclides. The efficient production of specific transuranic products requires consideration of the irradiation cycle in the reactor and separation of intermediate products for further irradiation. 

Plutonium is manufactured in megagram quantities neptunium, americium, and curium in kilogram quantities californium in gram amounts berkelium in 100-milligram amounts and einsteinium in milligram quantities. Chemical separations play a key role in the manufacture of actinide elements, as well as in their recovery, and analysis in the nuclear fuel cycle. This collection of timely and state-of-the-art topics emphasizes the continuing importance of actinide separations processes. 

The Cleanex Process A Versatile Solvent Extraction Process for Recovery and Purification of Lanthanides, Americium, and Curium... 

H. T., "Flowsheet for Recovery of Curium from Power Reactor Fuel Reprocessing Plant Waste," BNWL-1831, Battelle Pacific Northwest Laboratory, Richland, WA (197 ) ... 

The americium and curium isotopes formed during irradiation of nuclear reactor fuels are diverted into the high-level waste (HLW) stream during fuel reprocessing. The HLW is thus the biggest potential source for these elements, and R+D activities to develop a process for the recovery of Am and Cm from HLW were started in 1967. A major condition was that the process to be developed must not essentially increase the waste amount to be processed further, must not use strongly corrosive reagents, and must be compatible with the final waste solidification procedure. 

Chemical separation. Current concepts for high-efficiency separation of actinides call for improved plutonium recovery, coextraction of uranium and neptunium with subsequent partitioning by valence control, and extraction of amercium and curium from the HAW stream. There are a number of major problems to be solved before a technically feasible process will be available. 

Each of these elements may be used for production of nuclear fuel or other purposes. The recovery efficiency for uranium is reported as 99.87% and for plutonium 99.36%-99.51% (NEA 2012). The extended PUREX includes separation of neptunium and technetium as well as recovery of americium and curium that are also separated from each other by additional extraction stages as given in detail in the flowsheet (NEA 2012). The advanced UREX-i-3 process generates six streams after separation uranium for re-enrichment Pu-U-Np for mixed oxide fuel c for managed disposal Am-Cm to be used as burnable poisons and for transmutation high-heat-generating products (Cs and Sr) and a composite vitrified waste with all other fission products. Some fuel types may require preliminary steps like grinding to enable their dissolution. 

Only HDEHP has found large-scale use for the recovery and separation of americium however, other organophosphorus acids have been evaluated. Bis(2-ethylhexyOphenylphosphonic acid (HEH0P) was used to separate americium and curium from transcurium elements contained in 1 m HCI [52]. 

---