Experiences of occupational dose reduction at the Fugen nuclear power station

Occupational radiation dose has been effectively suppressed by efforts against both internal and external exposure in the Fugen nuclear power station. The tritium internal dose is completely suppressed by developments of high sensitivity tritium monitors with hollow fiber radon filters, comfortable tritium protection suits, and established working procedure for equipment maintenance of the heavy water system. The internal occupational dose has been suppressed to a negligible level comparing to the external dose. The external occupational dose had increased with dose rates of the primary cooling system. Establishment of radiation work procedure for maintenance works and development of chemical decontamination has been effectively saving the external occupational dose. The chemical decontaminations carried out in 1989 and 1991 are the first applications to the whole primary cooling system of operating power stations in Japan. This paper describes these efforts and effects on occupational dose reduction in Fugen. (author)