Recovery from power reactor fuels

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. 

Koch, G. "Recovery of by-product actinides from power reactor fuels and production of heat-source isotopes",... 

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

Recovery of By-Product Actinides from Power Reactor Fuels and Production of Heat Source Isotopes... 

The present paper reviews the processes which were designed by IHCH for the recovery of raw-material actinides from power reactor fuels and for the production of heat-source isotopes, and describes the state of development which has been reached. 

K4. Koch, G. Recovery of Actinides from Power Reactor Fuel, Report KFK-976, 1969. 

Origins. Most of the radioactive waste at SRP originates in the two separations plants, although some waste is produced in the reactor areas, laboratories, and peripheral installations. The principal processes used in the separations plants have been the Purex and the HM processes, but others have been used to process a variety of fuel and target elements. The Purex process recovers and purifies uranium and plutonium from neutron-irradiated natural uranium. The HM process recovers enriched uranium from uranium—aluminum alloys used as fuel in SRP reactors. Other processes that have been used include recovery of and thorium (from neutron-irradiated thorium), recovery of Np and Pu, separation of higher actinide elements from irradiated plutonium, and recovery of enriched uranium from stainless-steel-clad fuel elements from power reactors. Each of these processes produces a characteristic waste. 

This Symposium has been organized about new concepts, new systems, and new developments in actinide separations methodology. Much of the work reported here is based on fundamental actinide chemistry developed since the Manhattan Project days. The chapters in this volume describe ion exchange, solvent extraction, precipitation, pyrochemical, photochemical, and other methods of actinide separations as well as application of these separation methods to power reactor fuel reprocessing and recovery of actinides from waste solutions. 

The operations and facilities include ore exploration (not included in NFCIS list), mining, ore processing, uranium recovery, chemical conversion to UO2, UO3, UF4, UFg, and uranium metal, isotope enrichment, reconversion of UF to UO2 (after enrichment), and fuel fabrication and assembly that are all part of the front end of the NFC. The central part of the NFC is the production of electric power in the nuclear reactor (fuel irradiation). The back end of the NFC includes facilities to deal with the spent nuclear fuel (SNF) after irradiation in a reactor and the disposal of the spent fuel (SF). The spent fuel first has to be stored for some period to allow decay of the short-lived fission products and activation products and then disposed at waste management facilities without, or after, reprocessing to separate the fission products from the useful actinides (uranium and plutonium). Note the relatively large number of facilities in Table 2.1 dedicated to dealing with the spent fuel. Also listed in Table 2.1 are related industrial activities that do not involve uranium, like heavy water (D2O) production, zirconium alloy manufacturing, and fabrication of fuel assembly components. 

Influence of the downstream plants. Up to now, we have regarded the coal gasification reactor with the waste heat recovery system as an isolated unit. In the event that the gas generated is intended to be used as fuel gas, for example in a combined power station, this approach is justified. If, however, the gas is to be used as synthesis gas, the effect of the downstream units must be taken into consideration. In such cases it is necessary to feed the gas to a CO shift conversion unit in order to obtain the C0/H2 ratio required for the synthesis process. Apart from gasification at atmospheric pressure, which requires an intermediate compression step, it has proved advisable to locate the CO shift conversion directly downstream of the gasification section. A stage in which dust particles are removed from the gas is situated between these two units. It is assumed that exergy losses do not occur in this unit. 

Radioactive waste treatment applications have been reported [3-9] for the laundry wastes from nuclear power plants and mixed laboratory wastes. Another interesting application of reverse osmosis process is in decontamination of boric acid wastes from pressurized heavy water reactors (PHWRs), which allows for the recovery of boric acid, by using the fact that the latter is relatively undissociated and hence wdl pass with water through the membrane while most of the radioactivity is retained [10]. Reverse osmosis was evaluated for treating fuel storage pool water, and for low-level liquid effluents from reprocessing plants. 

The RCCAs of a reactor control protection system (CPS) are the most important elements of the reactor maintenance safe operation, which ensure control of reactor core power level and fast reactor core transfer from initial condition to sub critical condition during the accident. Share of RCCA in fuel reloading cost is 1-1,2%. However for CR materials choice it is necessary to take into account a possibility of inexpensive RCCA recovery or disposal. 

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