Part 21 Report - 1997-630
ACCESSION #: 9708050112
LICENSEE EVENT REPORT (LER)
FACILITY NAME: San Onofre Nuclear Generating Station Unit 2
PAGE: 1 OF 1
DOCKET NUMBER: 05000361
TITLE: Charging Subsystem Check Valve Failure
EVENT DATE: 06/26/97 LER #: 97-010-00 REPORT DATE: 07/28/97
OTHER FACILITIES INVOLVED: Unit 3 DOCKET NO: 05000362
OPERATING MODE: 1 POWER LEVEL: 100
THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR
SECTION:
50.73(a)(2)(i)
50.73(a)(2)(vii)
Other: Part 21
LICENSEE CONTACT FOR THIS LER:
NAME: R. W. Krieger, Vice President, Nuclear Generation
TELEPHONE: (714) 368-6255
COMPONENT FAILURE DESCRIPTION:
CAUSE: B SYSTEM: CV COMPONENT: V MANUFACTURER: K085
REPORTABLE NPRDS:
SUPPLEMENTAL REPORT EXPECTED: YES EXPECTED SUBMISSION DATE: 08/11/97
ABSTRACT:
On 6/26/97 while Unit 3 was shutdown for refueling, Edison found a check
valve in the Charging Subsystem that would not open completely. This
would cause the charging flow distribution to the Reactor Coolant System
to be different than that assumed in the safety analysis. Because of the
similarity of the Unit 2 Charging Subsystem, Edison immediately entered
the Technical Specification action statement. As a conservative action,
Edison also reduced Unit 2's power to about 90 percent, where charging
flow is not required for accident mitigation. On 6/28/97, Edison tested
Unit 2 and found that a similar check valve also would not open
completely. As required by the Technical Specifications, Edison shutdown
Unit 2 to repair the valve. Completion of that shutdown is being
reported as required by 10CFR50.73(a)(2)(i). Edison believes this valve
failure was caused by a design defect and is including 10CFR21
information in this report.
Edison replaced the faulty design valves in the charging injection lines
and auxiliary spray line in each unit with another type valve. Edison's
evaluation of the cause(s) is on-going. This LER will be revised.
Using an EPRI analysis program and actual, allowed, plant parameters,
Edison concluded that the condition resulted in a negligible increase in
plant risk and had no actual safety significance.
END OF ABSTRACT
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