ML20052A841
| ML20052A841 | |
| Person / Time | |
|---|---|
| Site: | Vallecitos File:GEH Hitachi icon.png |
| Issue date: | 05/04/1977 |
| From: | Darmitzel R GENERAL ELECTRIC CO. |
| To: | Stello V Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20052A734 | List:
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| References | |
| FOIA-81-483 NUDOCS 8204290260 | |
| Download: ML20052A841 (2) | |
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NUCLEAR ENERGY G E,'l E R A L h E L E CT R I C gnoon,ys o,y,sion GENERAL ELECTRIC C o M PA N Y, VALLECITOS NUCLEAR CENTER, PLEAsANTON, C A LIFO R NI A 94566 PHONE: (415) 862 2211 TWX:
910-548 8481 May 4, 7 7].,.
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'7 Mr. Victor Stello, Director
% 'D Division of Operating Reactors Office of Nuclear Reactor Regulation
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U.S. Nuclear Regulatory Commission Washington, D. C.'20555
Reference:
License TR-1, Docket 50-70
Dear Mr. Stello:
During a routine startup of the General Electric Test Reactor (GETR) at the Vallecitos Nuclear Center (VNC) on April 24, 1977, the neutron detector power indicator channels were erroneously adjusted.
This resulted in overpcwer trip settings on the three nuclear instruments with overpower trip protection (2-out-of-3 coincidence) exceeding the limits of Table II of the GETR Technical Specifi-cations. This occurrence is considered reportable pursuant to Section 3.D.(1) of License TR-1.
The reactor startup was begun, and the reactor power was increased to 10 MW as i
indicated by picoammeter #2. A heat balance was performed, and the power was calculated to be 11.9 MW. As required by operating procedures, the picoammeters and the flux amplifier channe.ls were adjusted so that all instruments indicated the calculated power, and the flux amplifier channels and picoammeter #1 were placed in the 2-out-of-3 coincidence mode for overpower trip protection.
The power increase to 20 MW was then initiated.
During the power rise it was noted that both flux amplifier channel readings led the picoammeter indications.
Assuming an error in the flux amplifier indications, operating personnel adjusted the flux amplifier indicators to be consistent with the picoameter readings.
Upon reaching 20 MW as indicated by the nuclear instrumentation, a heat balance was perfomed which indicated a power level of 39.7 MW. The rise to full power was halted, and an investigation was initiated to determine the cause of the discrepancy between the instrumentation and the heat balance calculation.
8204290 W
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GENER AL $ ELECTRIC Mr. Victor Stello May 4, 1977 The investigation revealed that while at 11.9 MW both picoammeter indicators l
had been set on the second from the top range rather than the top range, and subsequently the instruments were read as though they had been set on the top range. Thus the picoammeter readings indicated a lower power than was actually the case.
As a result of this error and the subsequent adjustment of the flux amplifier indicators, the trip settings on the nuclear instruments exceeded the limitations Table II of the Technical Specifications. The 2-out-of-3 coincidence system l
was not effectively operative for a period of approximately 15 minutes.
All instrumentation was correctly adjusted before the startup was resumed.
No power, rate of power increase, or temperature limits for the reactor were exceeded l
during the power rise. Other scram protection, including redundant reactor inlet and outlet high temperature channels, remained operative throughout the startup.
This occurrence was reported to the Commission's Region V office by telepho~ne on April 25,1977.
In order to prevent recurrence of this situation, Standard Operating Procedures pertaining to the nuclear instrumentation and reactor startup will be reviewed and necessary revisions made. The establishment of a system of independent verification of actions that directly affect the setting of safety system trip points by licensed reactor operators will be included in the revision. We currently plan to complete this action by May 31, 1977.
A special lecture wi.ll be conducted for all licensed operators and trainees in order to review this occurrence and to emphasize the procedures for handling variability encountered in instrument responses. This additional training will be completed by June 30, 1977, and in addition, all future requalification lectures pertaining to nuclear instrumentation will include the same subject.
Sincerely, l
R. W. Darmitzel i
Manager Irradiation Processing Product Operation vcc cc:
R. H.Engelken, Director Office of Inspection and Enforcement Region V U.S. Nuclear Regulatory Commission Suite 202, Walnut Creek Plaza 1990 North California Boulevard Walnut Creek, Ca. 94596
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