Reprocessing plants Hanford

U.S. plants. The principal U.S. reprocessing plants are listed in Table 10.3, together with their main process features. All use some form of the Purex process. In 1979, the only ones operating were the Savannah River and Idaho plants of the U.S. Department of Energy (DOE). The Hanford plant had been used primarily for recovery of plutonium and uranium from irradiated natural uranium, but was versatile and had been used, for example, for Thorex... 

Neutralized waste may develop another problem. Sludge will be formed that will carry most of the radioactivity and will eventually settle. That happened at Hanford, Savannah River, and at the Nuclear Fuel Services plant at West Valley, New York, the first commercial reprocessing plant, which is now out of operation. Considerable problems will have to be solved there to transfer the waste entirely from the storage tanks to a final treatment facility. 

Only 4-5 % of the utilized nuclear fuel worldwide is reprocessed. Commercial, nonmilitary, reprocessing of nuclear fuel takes place in France, Japan, India and the United Kingdom. Other reprocessing plants defined as defense-related are in operation and producing waste but without discharges. For example in the USA, at the Savannah River Plant and the Hanford complex, about 83 000 m and 190 000 m, respectively, of high-level liquid waste was in storage in 1985. 

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 These early extractants have now been replaced by tributylphosphate [TBP], diluted in an aliphatic hydrocarbon or mixture of such hydrocarbons, following the discovery of Warf [9] in 1945 that TBP separates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... 

Variants of the Purex (Pu-U Reduction Extraction) process are the most widely used plutonium-reprocessing schemes worldwide. Purex on the industrial scale began at the US Savannah River Plant in 1954 and replaced the Redox process at the Hanford works in 1956 every country that has produced significant quantities of plutonium has exploited the method. In Purex, the organic extractant is tributyl phosphate (TBP). In addition to optimum com-plexation properties for nuclear analytes of interest, TBP has a low aqueous solubility and is chemically and radiolytically stable. The density of TBP (0.98 g/cm ) is so close to that of water that it is common to dilute it in a lower density solvent. It is completely miscible with common organic solvents (e.g., kerosene, n-dodecane) at ordinary temperatures. 

At the Hanford plant, a variety of irradiated fuel elements require safe storage prior to reprocessing. Arrays of such subcritical units may be safely stored in water if a water gap between units, s ifficient to inhibit excess neutron interaction, is provided. The size of the gap is limited by the composition of the unit, the k-effec-tive of the unit and the maximum k-effective permitted for the array. In the past, a computer calculation has often been necessary to determine array safety but a simple relationship for determining safe unit spacing for less than complete isolation has been developed which can be used in many studies and which can reduce computer calculation. 

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