ML19345G106
| ML19345G106 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 01/31/1975 |
| From: | Crane P PACIFIC GAS & ELECTRIC CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| 1222, NUDOCS 8103020402 | |
| Download: ML19345G106 (2) | |
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Director N
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U. S. Nuclear Regulatory Commission
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Washington, D. C. 20555 Re:
Docket No. 50-133
Dear Sir:
Pursuant to Section IX.H.2.b. (2) of Appendix A to the Humboldt Bay Unit No. 3 Facility Operating License, we are hereby notifying you that the setpoint of one of the two suppression chamber vacuum relief valves was found to be out of tolerance in the non-con-servative direction.
The setpoint of the suppression chamber vacuum relief valves should be 2.0+0.5 inches of water as specified in Section III.B.5.c.
of the Technical Specifications.
During the monthly operational test on January 3, 1975 it was discovered that both valves were sticking and that the setpoint of one of the valves was out of tolerance at 3.0 inches of water.
The one out of tolerance setpoint did not render the suppression chamber vacuum relief protection system inoperable because the second redundant valve operated within the specified l
tolerance.
Both valves had been tested satisfactorily on December 10, 1974 following the routine maintenance which was performed on them in November during the 1974 regularly scheduled refueling outage.
Immediately following the discovery of the setpoint drift on Janu-ary 3, 1975 both valves were inspected and found to be clean and not damaged, although it appeared that there was inadequate dry lubricant on the discs and seats.
Both valves were re-lubricated and retested satisfactorily with no seat to disc sticking.
The relief valves were retested again a week later on January 10, 1975 and operated satis-factorily.
There has been one previous incident of setpoint drift of these valves due to sticking of the disc and seat, and this was re-ported in the Unit No. 3 semi-annual operating report for the period P00R ORIGINAL.
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Director January 31, 19,75 Division of Reactor Licensing Page 2 January 1, 1969 through June-30, 1969.. The corrective action taken as a result of this first incident has elimi).ted the sticking problem, provided sufficient lubricant is applied following valve maintenance.
Based on the satisfactory retest of January 10 and the application of adequate lubricant, the testing frequency has been returned to monthly.
The relief valves are 4-inch vacuum reliefs model 364 series manufactured by Varec Company.
There was no activity released, no per-sonnel exposure or injuries, no off-site consequences nor damage to the facility as a result of this incident.
Very truly yours, Aq
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CC:
Mr. R. H. Engelken, Director Office of Enforcement and Inspection Region V
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