Water chemistry experience at the Shimane nuclear power station unit 2 and application of the unit 1

The Shimane nuclear power station No. 1 unit (NS-1) is a 460-MWe BWR power station that has been operating for over 10 years at a primary piping system dose rate of less than 0.5 mSv/h. The occupational radiation exposure has been kept low by holding the amount of crud brought into the nuclear reactor from the feedwater as low as possible. Meanwhile, the Shimane No. 2 unit (NS-2) has been designed on the basis of experience gained from NS-1 to attain even lower dose rate for both the primary piping system and the occupational exposure. Because of the techniques used to control the chemistry of the reactor water and the amount of radioactive deposits in the primary piping system developed at NS-1 and elsewhere in Japan for advanced BWRs, NS-2 is expected to remain a plant with exceptionally low radiation levels. (author)