ML19345G119
| ML19345G119 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 06/25/1974 |
| From: | Searls F PACIFIC GAS & ELECTRIC CO. |
| To: | Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| 6011, RO-DPR-7-74-2, NUDOCS 8103020500 | |
| Download: ML19345G119 (2) | |
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PAC I F' I C GAS AND E LE C T R,I C C O M PANY EOU6 l
77 BEALE STREET. SAN F R A N CI S CO. C A LI F O R N I A 9 410 6. (415 ) 781 4211 P R E D E RIC K T. S E A R LS m.s s e..
June 25,1974
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a Mr. Donald J. Skovholt a
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U. S. Atomic Energy Commission b j gg Washington, D. C. 20545 Re:
Docket No. 50-133 Humboldt Bay Power Plant
Dear Mr. Skovholt:
This report is submitted in accordance with the requirements of Section IX.H.2.a. (1) of the Technical Specificacions of License No.
Notification of this occurrence was made via phone to the office of the Director of Region V Regulatory Operations on the day of the oc-currence.
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Report Number:
DPR-7/74-2 Report Date:
6/25/74 DD Occurrence Date:
6/17/74 9k Facility:
Humboldt Bay Power Plant Unit No. 3, Eureka, California D/
s f( > \\ h Identification of Occurrence:
A condition occurred involving the trip setting of picoammeter No. 2 which was less conservative than the limit-ing setting established in the Technical Specifications Table VI-1.
I Description of Occurrence:
At 0700 hours0.0081 days <br />0.194 hours <br />0.00116 weeks <br />2.6635e-4 months <br />, while performing the daily l
picoammeter trip setting test, no trip was observed upon reaching 123%
on the No. 2 picoammeter.
The operator did not attempt to increase i
the trip setting beyond 123% since this is the maximum allowable devi-ation (120 + 3%) on a Hi Flux Trip.
The Shift Foreman was not fied and the test was repeated four times.
A high flux trip signal occurred within the specified trip tolerance limits during each of the repeat j
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O Mr. Lural J. Skovholt 2
June 25, 1974 Designation of Apparent Cause of Occurrence:
The picoammeter was ex-changed with the spare and a complete inspection performed.
The in-spection of the picomumeter revealed that the trip circuit and 150 volt internal power supply components had degraded to the point where set point drift could occur.
Analysis of Occurrence:
Had a high flux condition occurred, the reactor would have tripped as designed at 120 1 3% since only two of the three picoammeters are required to initiate a high flux reactor trip.
Corrective Action:
All degraded components were replaced and the picoammeter was bench tested in accordance with General Electric instruction manual procedures.
The daily trip test and routine inspection of the picoammeters has proven sufficient in the past to detect component degradation and no increase in surveillance is planned.
Failure Data:
This is the first failure of this type that has caused a trip setting to be outside of Technical Specification limits.
The unit involved was a General Electric catalogue No. 8NCOl picoammeter.
Very truly yours, e
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Mr. R. H. Engelken, Director Directorate of Regulatory Operations Region V P. O. Box 1515 Berkeley, California 94701 i
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