ML20095L606
| ML20095L606 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 08/06/1984 |
| From: | Mangan C NIAGARA MOHAWK POWER CORP. |
| To: | Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| (55(E)-84-24), (NMP2L-0121), (NMP2L-121), NUDOCS 8408300365 | |
| Download: ML20095L606 (2) | |
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- i., - a" Y NIAGARA NUMOHAWK NIAGARA MOHAWK POWER CORPORATION /300 ERIE BOULEVARD WEST. SYRACUSE. N.Y.13202/ TELEPHONE (315) 474-1511 s
August 6, 1984 (NMP2L 0121)
Mr. R. W. Starostecki, Director U.S. Nuclear Regulatory Commission Region I Division of Project and Resident Programs 631 Park Avenue King of Prussia, PA 19406 Re: Nine Mile Point Unit 2 Docket No. 50-410
Dear Mr. Starostecki:
Enclosed is a final report in accordance with 10CFR50.55(e) for the problem concerning the sizing of Residual Heat Removal System safety valves.
This problem was reported via telecon with S. Collins of your staff on July 6, 1984.
Very truly yours,
[
C. V. Mang Vice President Nuclear Engineering & Licensing JM:ja Enclosure
'xc: Director of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 Project File (2) 8408300365 840806 PDR ADOCK 05000410 S
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lygf NIAGARA'M0 HAWK POWER CORPORATION NINE MILE POINT - UNIT 2 DOCKET N0. 50-410-I
- Final Report for a Problem Concerning the Sizing of Residual Heat Removal System Safety Valves
-(55(e)-84-24)
Descriptior.-of the Problem-
'The problem concerns the sizing of-safety valves 2RHS*SV34A,8 and 2RHS*SV62A,8 which are located on the steam supply piping to the residual heat removal system heat exchangers.
The safety valves provide overpressure protection for the heat exchangers in the event that the upstream pressure control valves, 2RHS*PV21A,B, fail in a wide _open position. The total relieving capacity of the safety valves is-approximate'y 413,000 lb/h/ loop.
It was determined that each pressure control valve could pass a maximum of approximately 1,100,000 lb/h/ loop in a wide open position. This difference in the capacity of the safety valves and pressure control valves could result in a significant overpressure condition within the heat exchanger and connecting piping, valves and instrumentation.
This overpressure-condition could result-in the heat exchanger / Residual. Heat Removal System not performing its design function.
Analysis'of Safety Implications This problem could have resulted in the loss of the A and/or'B loop of the Residual Heat Removal System.
Therefore, if the problem was to have remained uncorrected, it could have adversely affected the safety of operation of the plant.
Corrective Action The pressure control valve internals will be modified so that they will not pass flow in excess'of the capacity of the safety valves. This modification involves the replacement of the cage within each pressure control valve and will be completed by December 3, 1984.
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