Windscale reprocessing plants

A second source of plutonium, dispersed more locally, is liquid effluent from fuel reprocessing facilities. One such is the fuel reprocessing plant at Windscale, Cumbria in the United Kingdom where liquid waste is released to the Irish Sea(6). Chemical analysis of this effluent shows that about one percent or less of the plutonium is in an oxidized form before it contacts the marine water(7). Approximately 95 percent of the plutonium rapidly adsorbs to particulate matter after discharge and deposits on the seabed while 5 percent is removed from the area as a soluble component ). Because this source provided concentrations that were readily detected, pioneering field research into plutonium oxidation states in the marine environment was conducted at this location. 

Irish Sea, site impacted by Windscale Reprocessing Plant and reference sites, 1977 EPA 1984... 

A cluster of cases of childhood leukemia has been found in West Cumbria (Forman et al., 1987). As a result, an exhaustive reexamination has been made of the emissions from the Windscale piles and the adjacent Sellafield reprocessing plant, including those before,... 

Sources and Amounts of Plutonium in the Environment. Since 1945 approximately 3300 kg of plutonium has been injected into the environment, mostly (>90Z) from atmospheric explosions of nuclear weapons. This corresponds to about 380 kCi total alpha radioactivity. The addition to this amount by releases from nuclear power operations is much smaller the major continuing addition is ca. 0.1 kCi per month released to the Irish Sea from the British nuclear reprocessing plant at Windscale. About 2/3 of the plutonium from nuclear explosions would be formed into highfired oxides which would be rather inert chemically. However, the remainder, created during the explosion as single atoms via the U(n, J ) U(28 ) Pu... 

For the larger oxide-fuelled PFR, collocation of the reactor and its associated fuel plants was not practicable. The larger quantities of fuel involved favoured the industrial scale involvement of British Nuclear Fuels, whose Magnox reactor fuel reprocessing plant at Sellafield would provide the initial plutonium inventory. It was, therefore, decided that the PFR oxide fuel fabrication plant would be built and operated by BNFL at Sellafield and that fuel would then be transported to Dounreay as completed assemblies ready, after inspection and adjustment of the coolant flow control gags, for irradiation. The small experimental fast reactor fuel fabrication plant was moved from Dounreay to the AEA s Windscale Laboratory, adjacent to BNFL Sellafield, to provide R D support to the main fuel fiibrication plant and to supply small batches of experimental variants for incorporation by BNFL into DMSA clusters and driver fuel assemblies. 

The rate of dissolution of these reaction products is slow (1.5-2 fig/day per 50-70 mg of solids). Lai and Goya 147) showed that at least 90% of these plutonium aggregates had a diameter <0.01 jum. However, it must be stressed that these forms do not necessarily represent those forms which would be produced as a result of an accidental release from a nuclear power plant or as a result of controlled release from nuclear fuel reprocessing facilities such as those which occur at Windscale in England. 

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... 

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. 

British Nuclear Fuels pic (BNFL) provide a complete nuclear fuel cycle service with its sites at Springfields (AGR/Magnox Fuel Fabrication) near Preston and Sellafield (MOX Fuel Fabrication and Reprocessing) in Cumbria. BNFL also generates electricity using Magnox Reactors at Sellafield (Calder Hall) and Chaplecross in Scotland. This paper provides an overview of the Windscale Vitrification Plant (WVP) and reviews the major safety issues associated with vitrification operations. The practicalities of vitrification of Pu using the current WVP process are briefly discussed. 

The Windscale Vitrification Plant vitrifies high level (highly active) liquid waste arising from reprocessing operations at Sellafield. The plant operates two identical vitrification lines with a current combined throughput of 350 product containers per year. A third line is currently under construction and will commence operation in the year 2000. The key safety function of the plant is to convert mobile material into a solid immobile form which can be more easily managed, stored, and transported. 

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