ML20215J837
| ML20215J837 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 10/08/1986 |
| From: | Tucker H DUKE POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8610270206 | |
| Download: ML20215J837 (2) | |
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DUKE POWER GOMPANY P.O. BOX 33180 CHARLOTTE, N.C. 28242 HALH. TUCKER
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86 0CT IS Pl2: 3s October 8, 1986 Dr. J. Nelson Grace, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Re:
Catawba Nuclear Station, Unit 1 Docket No. 50-413
Dear Dr. Grace:
Please find attached a Revision to the Special Report dated September 9,1986 which concerned the automatic opening of a pressurizer power-operated relief valve.
Very truly yours, s
BA/
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Hal B. Tucker RWO/36/slb Attachment xc: Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
20555 NRC Resident Inspector Catawba Nuclear Station 8610270206 861008 PDR ADOCK 05000413 S
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Special Report Lifted Valve INC34 (NC PORV)
Circumstances Initiating the Transient:
l On August 10, 1986 during unit shutdown, the pressurizer PORV's were placed in the low pressure (L/P) mode without incident.
If Reactor Coolant (NC) System temperature is below 300 degrees F, placing the PORV's in the L/P mode reduces the lift setpoint to 400 psig and opens the backup nitrogen supply to the valve operator. During the shutdown, NC temperature fell below 300 degrees F and the nitrogen supply to valve INC34 (pressurizer PORV) opened. This was expected.
However, at the same time, valve INC34 also opened. This should not have occurred.
Reactor Coolant System pressure at this time was approximately 349 psig. Valve INC34 and its block valve were closed by the operator.
The valve remained closed until the valve and its associated circuitry were checked out.
Effect of PORV on the Transient:
Reactor Coolant System pressure was approximately 349 psig throughout this event.
There was no real pressure transient for the PORV to alleviate.
Corrective Action to Prevent Recurrence:
Personnel have recalibrated the instrumentation loop associated with valve INC34.
This action should prevent recurrence.
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