ML19317D763
| ML19317D763 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/17/1977 |
| From: | DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML19317D758 | List: |
| References | |
| RO-269-77-06, RO-269-77-6, NUDOCS 7912100526 | |
| Download: ML19317D763 (1) | |
Text
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DUKE POWER COMPANY OCONEE UNIT 1 0
Report No.:
R0-269/77-6 Report Date: March 17, 1977 Occurrence Date:
February 25, 1977 Facility:
Oconee Unit 1, Seneca, South Carolina Identification of Occurrence: Failure of a HPI letdown isolation valve lHP-5, which is also a Reactor Building containment isolation valve Conditions Prior to Occurrence: Unit at 98 percent full power Lescription of Occurrence:
On February 25, 1977, Reactor Building containment isolation valve, lHP-5, failed in the normal ES closed position. This valve is located in the reactor coolant letdown line for the High Pressure Injection System and provides containment isolation upon an ES actuation. A work request was issued to investigate the problem, and within one hour the valve was opened by bypassing the control solenoid.
The valve was then manually operable and a person was assigned to close the valve if necessary.
During the incident, the pressurizer level increased above the station operating limit of 300 inches, therefore, a reactor shutdown was initiated. Within fifteen minutes the pressurizer level was within the operating limits and the shutdown was terminated. Valve lHP-5 was repaired and its operability verified within the four hours as specified by Technical Specification 3.6.4.6.1.
Apparent Cause of Occurrence:
l This incident resulted from the electrical failure of the solenoid coil.
Inalysis of Occurrence:
l l
Technical Specification 3.6.4.b.1 specifies that a containment isolation l
valve may be inoperable provided that the inoperable valve is restored to operable status within four hours. Valve lHP-5 was verified operable within this time period.
In the event that containment isolation had been required during the brief interval valve lHP-5 was inoperable, the redun-dant valves lHP-3 and lHP-4 would have closed upon an ES actuation.
Con-tainnent integrity was not affected by this incident and therefore it is l
concluded that the health and safety of the public was not affected.
Corrective Action:
The solenoid of valve lHP-5 was bypassed allowing the valve to be manually operated by an air regulator. A person was assigned to close the valve if this action was needed while the lHP-5 controls were bypassed.
The solenoid coil was replaced. The valve was tested and returned to service.
Further corrective action is considered unnecessary.
191210 0 SM
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