Windscale Separation Plants

Windscale II plant in the UK. In this the uranium and plutonium are back-extracted together in a first cycle of decontamination. They are then separated in a second cycle of solvent extraction and independent back-extraction. The factors affecting the choice of flowsheet type have been reviewed and criticality control is an important consideration in the process design.286... 

Huggard, A.J., Warner, B.F. 1963. Investigations to determine the extent of degradation of TBP/odorless kerosene solvent in the new separation plant, Windscale. Nucl. Sci. Eng. 17 638-650. 

Table 2.3 shows the estimated releases of 90Sr, 131I, 137Cs and 144Ce in the Nevada tests, the thermonuclear tests (H tests), the 1957 Windscale accident, the 1957 accident at a separation plant in the Urals... 

A solvent extraction process similar to Purex using TBP was developed by the Commissariat a I Energie Atomique [Gl] for use in the French plutonium separation plant at Marcoule. Since then, the Purex process has replaced the Butex process at Windscale [W3], has been used in the Soviet Union [Sll], India [S7], and Germany [S3], and by now is the universal choice for separation of uranium and plutonium from fission products in irradiated sUghtly enriched uranium. Fuel from the liquid-metal fast-breeder reactor (LMFBR) is also reprocessed by the Purex process, with modifications to accommodate the higher concentrations of plutonium and fission products. 

In 1942, the Mallinckrodt Chemical Company adapted a diethylether extraction process to purify tons of uranium for the U.S. Manhattan Project [2] later, after an explosion, the process was switched to less volatile extractants. For simultaneous large-scale recovery of the plutonium in the spent fuel elements from the production reactors at Hanford, United States, methyl isobutyl ketone (MIBK) was originally chosen as extractant/solvent in the so-called Redox solvent extraction process. In the British Windscale plant, now Sellafield, another extractant/solvent, dibutylcarbitol (DBC or Butex), was preferred for reprocessing spent nuclear reactor fuels. These early extractants have now been replaced by tributylphosphate [TBP], diluted in an aliphatic hydrocarbon or mixture of such hydrocarbons, following the discovery of Warf [9] in 1945 that TBP separates tetravalent cerium from... 

Following successful pilot-plant tests at Chalk River [N4], the Butex process was adopted for large-scale separation of plutonium, uranium, and fission products from natural uranium irradiated to low bumup at the Windscale plant of the U.K. Atomic Energy Authority [H8]. Even after its use in this application was replaced by the Purex process, the Butex process remained in use at Windscale for primary decontamination of high-bumup fuel until the 1970s. Then an explosion, probably due to reaction of nitric acid vnth solvent, terminated its use. 

A small amount of irradiated material had been supplied to the Canadians by the Americans, which could then be used to investigate the chemistry of plutonium. The basic research for the Windscale chemical processes was done at Chalk River, Canada, using some 20 milligrams of plutonium. One major result of the work was the demonstration that a separation of plutonium, uranium and fission products was possible by the use of suitable organic solvents. Numerous solvents were investigated and finally dibutyl carbitol was chosen. An experimental plant was built at Chalk River based on dibutyl carbitol and an aqueous phase flowing coimter-current in simple random-packed coluiims. Between October 1949 and April 1950 newly recruited members of the Windscale chemical staff worked at Chalk River to gain experience in the operation of the experimental plant. 

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