Results of the 8th regular inspection of Unit 1 in Fukushima No. 1 Nuclear Power Station

The 8th regular inspection of Unit 1 in the Fukushima No.1 Nuclear Power Station in fiscal 1981 was carried out from April 11, 1981, to January 8, 1982. Inspection was made on the reactor proper, reactor cooling system, instrumentation and control system, waste management, reactor containment, etc. By visual, disassembling, leakage, functional, performance and other inspections, the results were as follows. (1) Pitting corrosion was detected on the weld line of the main shell in a liquid waste concentrator. (2) Leakage was suspected in three fuel assemblies. Radiation exposure dose during the inspection was all below the permissible level. During the regular inspection, the following improvement works and others were done: the countermeasures to stress corrosion cracking (the repair of the emergency condensation system and of the boric-acid water injection system), safety reinforcement, the replacement of four main steam relief valves and of the steam-bleeding pipes and feed water heaters, and the repair of the liquid waste concentrator. (Mori, K.)