On abnormalities and failures in nuclear power stations in fiscal 1983

The number of the abnormalities and failures reported by electric power companies to the Agency of Natural Resources and Energy on the basis of the relevant laws was 27. When these 27 abnormalities and failures were classified according to the main causes due to management factors, those due to improper design management were 4 cases, those due to improper manufacturing management were 8 cases, those due to improper construction management were 2 cases, those due to improper maintenance management were 10 cases, and others were 3 cases. Among these 27 abnormalities and failures, those occurred during the operation of reactors were 16 cases, and those discovered during the stop for regular inspection were 11 cases. The 16 cases occurred during the operation of reactors were classified into 11 cases which caused the automatic stop by the action of protection equipment and 5 cases in which abnormality was discovered by patrol and inspection, and reactors were stopped for the repair. The 11 cases discovered during the stop for regular inspection were 6 cases of the damage of the heating tubes of steam generators, 2 cases of the damage of the supporting pins for control rod guide tubes. There was no effect of radioactivity to surrounding environment. Besides, 45 minor failures were reported. (Kako, I.)