United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 80-41: Failure of Swing Check Valve in the Decay Heat Removal System at Davis-Besse Unit No. 1

                                                           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. 

Page Last Reviewed/Updated Tuesday, November 12, 2013