Check Plan for Equipment Past Its Check Period at Hamaoka Nuclear Power Station Reactors No. 3, 4 and 5 and Investigation of Check Record
October 12, 2010
Chubu Electric Power Co.,Inc.
Following cases of inadequate maintenance management at other companies, Chubu Electric Power's Hamaoka Nuclear Power Station Reactor No. 3 has undergone a periodic safety management review by the Japan Nuclear Energy Safety Organization. The review revealed that the check on some equipment had been performed later than the check period required for that equipment.
Having learned this fact, Chubu Electric Power conducted an investigation on pieces of equipment subject to periodic licensee's inspection at Reactors No. 3, 4 and 5 to determine whether they had passed their check periods. The results indicated that, because of input errors (incorrect data input, or failure to register equipment number) concerning the check dates on the check plan control table, which determines specific equipment check dates based on check periods, there are currently 27 pieces of equipment (16 at No. 3, 11 at No. 4 and none at No. 5) that are past their check periods. These pieces of equipment are all valves, etc., that drain water during checks and do not need to be operated during accidents. Additionally, visual checks we have conducted at this time indicate no irregularities, and checks of similar devices recently also found no deterioration. Based on these and other results, Chubu Electric Power has concluded that equipment soundness has been maintained at this time and that it is possible to continue using the equipment without performing an overhaul until the periodic check that is coming up in the near future.
Additionally, in cases like this where equipment is found to have passed its check period, we decide whether to allow extending that check period after conducting an evaluation of such extension, but in the course of the investigation it was determined that the rules for equipment soundness evaluation processes were not adequately clear (for example, the valve check period requirements were vague and the rules for managing evaluation records were unclear and therefore the records were not saved).
Chubu Electric Power has summarized the results of our investigation of the situation and reported it today to the Nuclear and Industrial Safety Agency. In return, the agency has directed Chubu Electric Power to determine the causes of check period input errors, etc., and establish recurrence prevention measures; to establish improvement measures, such as clarifying procedures for extending and evaluating check periods; to conduct similar investigations on equipment other than that subject to periodic licensee's inspection and on equipment at Reactors No. 1 and 2; and to report by November 30, 2010. Chubu Electric Power intends to respond appropriately as directed by the agency.