ML17334B313
| ML17334B313 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 06/26/1989 |
| From: | Will Smith INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG |
| To: | Davis A NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8907060185 | |
| Download: ML17334B313 (3) | |
Text
4C CE1ZRATED D3 BUTION DEMO?iS 4,TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:8907060185 DOC.DATE: 89/06/24 NOTARIZED: NO DOCKET Tj FACIL:50-315 Donald C.
Cook Nuclear Power Plant, Unit 1, Indiana 05000315 AUTH.NAME-AUTHOR AFFILIATION SMITH,W.G.
(formerly Indiana
& Michigan Ele RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
SUBJECT:
RO:on 890611,pressurizer PORV NRV-153 opened automatically.
DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR U ENCL
/
SIZE:
TITLE: 50.73/50.9 Licensee Event Report (LER), incident Rpt, etc.
NOTES:
R'ECIPIENT ID CODE/NAME PD3-1 LA STANG,J INTERNAL: ACRS MICHELSON ACRS WYLIE AEOD/DSP/TPAB DEDRO NRR/DEST/ADE 8H NRR/DEST/CEB 8H NRR/DEST/ICSB 7
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LTTR 43 ENCL 42
Indiana Michigan Power Company Coo< Krrc ea'(an!
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June 26, 1989
~ NDMMA NlCHlGAN POWER Donald C.
Cook Nuclear Plant Unit No.
1 Docket No. 50-315 License No.
DPR-58 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C.
20555 ATTN:
A. B. Davis
Dear Mr. Davis:
This report is being submitted in accordance with Technical Specification 3.4.9.3 action c. for Unit One.
During cold shutdown operation, pressurizer power operated relief valve (PORV) NRV-153 opened automatically on June 11, 1989, at 1141 hours0.0132 days <br />0.317 hours <br />0.00189 weeks <br />4.341505e-4 months <br />.
The PORV opened after starting Reactor Coolant Pump (RCP)
No.
13 during the Reactor Coolant System (RCS) filland vent procedure.
There were no other RCPs running at the time.
Prior. to the pump start, the RCS was at approximately 350 psig and 145'F with a steam bubble in the pressurizer.
The RCS pressure increased to approximately 370 psig after the pump start and the PORV opened.
The PORV closed after approximately two seconds and the RCS pressure stabilized at approximately 350 psig.
The highest recorded pressure during this event was approximately 370 psig, which is below the 400 psig pressurizer PORV setpoint limit of Technical Specification 3.4.9.3.
The pressurizer PORV setpoints are (385 psig + 15) and the minimum pressure for operation of the RCPs during filland vent operations is 325 psig (to which we add 25 psig due to instrument uncertainties).
This gives an effective operating window of 20 psig.
Information supplied by the RCP vendor indicates that a pressure change of 30-40 psig could be expected when starting an RCP.
The problem of a very small operating window is recognized within the industry and potential resolutions are being pursued, A previously reported Unit Two event, which occurred on March 4,
- 1987, also involved problems caused by instrument uncertainties.
In that event the operators were controlling a gradual pressure increase based on a channel that was indicating 385 psig.
The redundant channel was indicating higher and the associated PORV was actuated when the Unit Two PORV setpoint of 420 psig + 15 psig was reached.
It was subsequently determined that both channels of pressure instrumentation were within allowable instrument tolerances.
We are currently in the process of having the PORV setpoints recalculated by the NSSS vendor using a refined method which should result in slightly higher setpoints and a larger operating window.
We are also studying the use of narrow range pressure instrumentation for cold overpressure PORV control to remove some of the instrument uncertainties and allow a higher setpoint.
Consideration was given to lowering the RCS pressure at which RCPs are
- started, but the RCP vendor has supplied information which warns that seal damage could occur if a RCP is started at less that 325 psig. It is therefore not desirable to start the RCPs at a pressure of less than 350 psig due to p'ressure instrument uncertainties.
Respectfully, W.
G. Smith, Jr.
Plant Manager cc:
D.
H. Williams, Jr.
A. B. Davis, Region III M. P. Alexich P.
A. Barrett R.
F. Kroeger NRC Resident Inspector J.
F.
Stang R.
C. Callen G. Charnoff, Esq.
Dottie Sherman, ANI Library D. Hahn INPO PNSRC A. A. Blind S. J.
Brewer / B.
P.
Lauzau