Results of the fifth periodic inspection of No. 2 plant in Mihama Power Station

The fifth periodic inspection of No. 2 plant in Mihama Nuclear Power Staton was carried out from March 20, 1979, to February 28, 1980. The results of inspection are outlined as follows. The check-up was carried out in consideration of the accident in Three Mile Island Power Station, but abnormality was not observed at all. The exposure dose of the workers during this periodic inspection is shown, and all the inspection works were accomplished within the dose value specified by the relevant law. The works carried out during this periodic inspection were as follows. The shape of the gripper finger of the fuel exchange crane was modified to avoid the interference with the spider vane of a secondary neutron source and the upper nozzle springs of fuel assemblies. As for the guide tubes of control rod clusters, 8 pulled out supporting pins were replaced with those of improved heat treatment and improved shape, and 16 defective deflection pins were replaced with those of improved heat treatment. All guide tube covers were replaced with those of improved shape. The signal of the abnormal low pressure in the reactor was added for automatically starting the emergency core-cooling system. 25 tubes of the steam generator were plugged because of cracking and leak. This is the report made by the Agency of Natural Resources and Energy in April, 1980. (Kako, I.)