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.
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