ML20148S259

Forwards Revised Response to NRC Re Violations Noted in Insp Rept 50-289/96-201.Corrective Actions:Util Is Proceeding to Implement Revs to Abnormal Transient Procedure 1210-07 to Limit LPI & Bs Flow Rates Where Necessary

ML20148S259
Person / Time
Site:	Three Mile Island
Issue date:	06/27/1997
From:	Keaten R GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
50-289-96-201, 6710-97-2283, NUDOCS 9707080146
Download: ML20148S259 (3)

Text

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Robert W. Keetes Vice President o.- ~** Engineering I GPU Nucleer, Inc.

\ One Upper Pond Roed NUCLEAR Persippany, NJ 07054-1095 Tel 201316 7112 Fox 201-31s-7431 June 27,1997 6710-97-2283 U.S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, DC 20555 ,

Gentlemen:

Subject:

Three Mile Island Nuclear Station, Unit I (TMI-1)

Operating License No. DPR-50 Docket No. 50-289 .

GPU Nuclear Response to inspection Repon 96-201 By letter dated June 23,1997, we transmitted the GPU Nuclear response to Inspection ,

Report (IR)96-201. The purpose of this letter is to amend that response to revise the planned corrective action for URI 96-201-14 " Adequacy of Safety Evaluation of FSAR Change (Section E.1.3.2.2.b). Namely, GPU Nuclear intends to modify operating procedures to restore conformance to the licensing basis rather than propose changes to the licensing basis as described in the June 23,1997 response.

i If you have any questions on this amended response, please contact us.

Sincerely, j 4

R. W. Keaten /

Vice President & Director /

Engineering WGH y Attachment cc: Administrator, Region I TMI Senior Resident Inspector TMl Senior Project Manager lilEIElEIHhE,Ellli 9707000146 970627 PDR ADOCK 05000209 G PDR

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PageIof2 URI 96-201-14. " Adequacy of Safety Evaluation of an FSAR Change (Section E.1.3.2.2 b)"

A. Description of the Finding: I Safety Evahiation (SE) No, 115403-004, Rev. O, did not identify that, because the required Net Positive Suction Head (NPSH) for the Decay Heat Removal (DHR) Pumps would not be met widiout I taking credit for containment overpressure, the probability of occurrence of malfunction of the DHR Pumps previously evaluated in the safety anal) sis report may be increased, and thus, a potential Unresiewed Safety Question (USQ) as defined in 10CFR50.59 was involved.

I B. Discussion:

i Safety Evaluation SE-Il5403-004, Rev. O, considered that the assumption of no credit for containment overpressure above the sump vapor pressure only applied to the licensing basis accident

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analysis condition of 3000 gpm Low Pressure injection (LPI) flow rate and 1500 gpm RB Spray flow '

rate, and adequate NPSH was demonstrated at these conditions. A flow rate limited to 3300 gpm by  ;

Abnormal Transient Procedure ( ATP) 1210-7, "Large Break LOCA Cooldown," was considered to be beyond the liccasing basis as presently defined by the TM1-1 FSAR and the NRC Safety Evaluation  ;

Report (SER) dated July 11,1973 for TMI-1. Since this condition was interpreted as being beyond the licensing basis, it was determined that use of conservative but more realistic assumptions in terms of containment overpressure was acceptable.

The existing licensing basis only addresses the accident analysis assumed LPI flow rate of 3000 gpm. l Safety Evahiation i15403-004, Resision 0, recognized that ATP 1210-7 allowed a higher LPI flow rate. This higher LPI flow rate provides additional margin beyond the accident analysis value in tenns of core cooling (10 CFR 50.46) concerns. The value used for the assumption on containment overpressure was conservative but reflected an expected Reactor Building response to the postulated design basis accident. Safety Evaluation 115403-004, Resision 0, determined the NPSH available to the DHR Pumps to be adequate at both the 3000 gpm accident analysis value and the 3300 gpm procedurally limited flow vr.lue. The calculated NPSH available for the DHR Pumps at conditions of 3300 gpm LPI and 1500 gpm RB Ta now was approximately 0.5 ft. (0.22 psi)less than required with no adi! f:: atamment overpressure based on a 1990 calculation and the associated safety evaluation. Abnormal Transient Procedure (ATP) 1210-07, "Large Break LOCA Cooldown," directs the operator to turn ofTthe RB Spray Pumps at a RB Pressure of 4.0 psig. Under this condition there is an excess available NPSH of 2.9 ft. Thus, additional NPSH margin is provided when considering the expected plant and operator response to the postulated design basis accident. No immediate j corrective actions were required since this condition only involves a reduction in the margin included l in the NPSH determination and does not represent a safety or operability issue.  !

While applying containment overpressure could legitimately be viewed as a design control concern under Appendix B to 10 CFR 50, at the preliminary enforcement conference on May 22,1997, GPU Nuclear questioned u hether SE No. I15403-004, Res ision 0, should have determined diat an unresiewed safety question existed by considering assumptions beyond the licensing basis. Safety Evaluation 115403-004, Revision 0, explicitly documented the rationale substantiating the safety evaluation conclusions, and conservatively incorporated instrument c Tor not presiously considered in the licensing basis. GPU Nuc1 car requested further consideration and guidance from the NRC StafT on this question. We suggested that safety evaluations should be performed in a manner consistent with licensing basis assumptions because the objective of those evaluations is to determine whether a change preserves the plant's licensing basis. Based on additional discussion with NRC Staff, GPU Nucicar understands that it is the NRC's position that use of containment overpressure for the 3300 gpm LPI flow rate is a desiation from the existing licensing basis. GPU Nuclear understands that 10CFR50.59 and USQ criteria interpretation is an evolving issue and is continuing to develop based on issuance of NRC document, SECY 97-035. We are participating in various industry groups related to this issue and continue to monitor these activitics to fully understand how to more efTectively address 10 CFR 50.59 criteria.

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I Accordingly, GPU Nuclear will establish and implement corrective actions which will ensure the LPI l pumps would have adequate NPSH available consistent with the existing licensing basis requirement i of no credit for containment overpressure other than the assumption of containment pressure equal to j; the vapor pressure of the sump water, as approved by NRC in Safety Evaluation Repon dated July 11, 1973. These corrective actions will restore compliance with the existing licensing basis.

C, Corrective Actions:

GPU Nuclear is proceeding to implement revisions to Abnormal Transient Procedure (ATP) 1210-07, "Large Break LOCA Cooldown", to limit LPI and BS flow rates where necessary to ensure that these pumps are operated under conditions where adequate NPSH is available without credit for containment overpressure. Evaluations supponing this procedure change will ensure that system safety functions and associated licensing basis requirements are maintained.

This corrective action will restore the existing licensing basis and climinate any potential for a USQ that may exist as a result of tle resised profile evaluated in Safety Evaluation 115403-004, Revision D.

D. Schedule for Completion of Corrective Actions:

The revisions to Procedure ATP 1210-07 and the supponing safety evaluation are being completed to i suppon stan-up from the present outage. Associated changes to engineering and design documentation will be completed by July 31,1997, I

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