Purpose: To decrease the exposure dose upon operation, maintenance and disassembly of a nuclear power plant by applying impact shocks to radioactive nuclides-containing oxides deposited to instruments and pipeways of the nuclear power plant and peeling off the oxides therefrom. Method: Into cleaning water for the instruments and pipeways of a nuclear power plant, particulate substances approximately of the same specific gravity as that of the cleaning water are added and circulated. The oxides containing radioactive nuclides deposited to the instruments and the pipeways are thus applied with impact shocks by the particulate substances and peeled off from the instruments and the pipeways. Then, after separating the particulate substances, the oxides in the cleaning water are filtered to clean the cleaning water. The generation of radioactive wastes can thus be supported, whereby the exposure dose upon operation, maintenance and disassembly of the nuclear power plant can be decreased. (Moriyama, K.). Saito,-Masayuki.
