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SSINS No.: 6835 Accession No.: 8008220260 IN 80-41 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 November 10, 1980 Information Notice No. 80-41: FAILURE OF SWING CHECK VALVE IN THE DECAY HEAT REMOVAL SYSTEM AT DAVIS-BESSE UNIT NO. 1 Description of Circumstances: On October 9, 1980 the resident inspector at the Davis-Besse facility was informed that the licensee had performed leak rate tests and identified excessive leakage through Decay Heat Removal System check valve CF-30. Valve CF-30 is the inboard one of two in-series check valves that is used to isolate the reactor coolant system from the low pressure decay heat removal system. On further investigation the licensee found that the valve disc and arm had separated from the valve body and was lodged just under the valve cover plate. The two 2 5/8 x 5/8 inch bolts and locking mechanism for the bolts that holds the arm to the valve body were missing and have not been located. The CF-30 valve is a 14-inch swing check valve manufactured by Velan Valve Corporation. The cause of the failure has not been identified. The test that was in progress when the failure was identified was being conducted in response to a letter from Darrell G. Eisenhut, Office of Nuclear Reactor Regulations to all Light Water Reactor Licensees, LWR Primary Coolant System Pressure Isolation Valves, February 23, 1980. This Information Notice No. is provided as an early notification of a possibly significant matter that is still under review by the NRC staff. It is expected that recipients will review the information for possible applicability to their facilities. No specific action or response is requested at this time. If NRC evaluations so indicate, further licensee actions may be requested or required. No written response to this Information Notice No. is required. If you have any questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
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