Features in the aspect of materials in reprocessing plants

The process of the reprocessing plant installed in Rokkasho, Aomori Prefecture, by Japan Nuclear Fuel Service Co., Ltd. is the Purex wet process experienced in Japan and abroad, and which can obtain the uranium and plutonium products of high purity at high recovery rate. This process is to melt spent fuel with nitric acid, and extract and separate uranium, plutonium and fission products from the obtained solution by utilizing the difference in chemical properties. The yearly amount of treatment of the reprocessing plant of this company is 800 t uranium. In order to ensure the safety in the reprocessing plant that handles the solution with high radioactivity, the function of confining radioactive substances in definite areas is demanded. For the purpose, the machinery, equipment and piping containing radioactive substances are made of the materials having the corrosion resistance against nitric acid, and welded structure is adopted to prevent leakage. Negative pressure is maintained in waste gas treatment facilities in relation to cells, and in the cells in relation to the building. The outline of the facilities, the materials of the main machinery and equipment, and the applied technologies are reported. (K.I.)