ML19345G110
| ML19345G110 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 01/03/1975 |
| From: | Crane P PACIFIC GAS & ELECTRIC CO. |
| To: | Goller K Office of Nuclear Reactor Regulation |
| References | |
| 142, RO-DPR-7-74-5, NUDOCS 8103020450 | |
| Download: ML19345G110 (3) | |
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Mr. Kar1 R. Go1ler
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Docket No. 50-133 c
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Dear Mr. Goller:
h This report is submitted in accordance with Section*fX.
H.2.a. (2) of the Technical Specifications of License No. DPR-7.
Notification of this occurrence was made via phone to office of the Director of Region V Regulatory Operations on December 26, 1974.
Report Number DPR-7/74-5 Report Date January 3, 1975 Occurrence Date December 24, 1974 Facility Humboldt Bay Power Plant, Ulit No. 3 Eureka, California Identification of Occurrence:
During the reactor startup of December 24, 1974 it was discovered that the feedwater control valve air supply was closed rendering the feedwater control valve unavailable for remote operation.
This valve is part of the high pressure core flooding system.
Description of Occurrence:
On October 30, 1974 the reactor was shutdown for a regularly scheduled refueling and maintenance outage.
During the initial startup following this outage, the feedwater control valve did not respond to an open signal from the operating console.
During this phase of the startup the reactor was at 1000 psig and approximately P00R ORIGINAL S
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k_I Mr. Karl R. Goller 2
January 3, 1975 40 MNt with the turbine bypass valves controlling reactor pressur '
(10% open).
An immediate investigation was made and the problem was traced to the control valve air supp?.y valve'which was closed rendering the control valve inoperable except in manual at the valve location.
The air supply was restored to normal, but the feedwater control valve could not be opened soon enough to keep the reactor from tripping on low reactor water level even though the control operator had started to insert control rods to reduce the flow of steam through the bypass valves and thus the feedwater flow requirement.
Designation of Apparent Cause of Occurrence:
During the outage the control valve and the controls were inspected.
Apparently following the inspection of the control system', which was done after the valve inspection, the control air supply valve was left in the closed posi-tion.
This was a maintenance error as normal practice is to restore the control system to operation prior to reporting off of the equip-ment.
Analysis of Occurrence:
Assuming that the high pressure core flooding system had been required to function due to a loss of coolant accident, it could have been made available by manually operating the feedwater control valve at the valve location in the auxiliary equipment room.
In addition, Ehe two low pressure core flooding systems were available and operable if they had been required to function.
Corrective Action:
The personnel responsible for controls maintenance have been cautioned to return systems worked on to an operable condi-tion before reporting clear of the equipment.
Following maintenance of the feedwater control valve or its control system, operations per-sonnel will be required to check the operability of the feedwater control valve by observing its movement at the valve as the console controls are manipulated.
This operability check of the feedwater valve and control circuit will also be added to the Cold Startup Check List, which is conducted prior to startup following all extended maintenance outages.
Failure Data:
Not applicable - maintenance error.
Very truly yours,
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Itr. R. H.
Engelken, Director Directorate of Regulatory Operations Region V
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