ML20079C809

Forwards Application to Amend to License DPR-16,changing Reduced APLHGR Limits When Redundant Core Spray Loop Not in Svc

ML20079C809
Person / Time
Site:	Oyster Creek
Issue date:	06/18/1991
From:	J. J. Barton GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20079C810	List: ML20079C809 ML20079C812 ML20079C820
References
C321-91-2157, NUDOCS 9106260140
Download: ML20079C809 (3)

Text

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8 g GPU Nuclear Corporation 1[Ma Q gf Post Ofhce Box 388 Route 9 South Forked River, New Jersey 087310388 609 971 4000 Water's Direct Dial Number:

June 18,1991 C321-91-2157 U. S. Nuclear Regulatory Commission Attna Document Control Desk Washington, DC 20555 Gentlemen Subjects Oyster Creek Nuclear Generating Station (OCNGS)

Docket No. 50-219 Technical Specification Change Request (TSCR) No. 160, Revision 2 References (1) GPUN letter dated 1/26/89 (2) GPUN letter dated 8/14/90 (3) NRC letter dated 3/29/91 In response to NRC staff concerne for ensuring 10CFR50.46 compliance, GPU Nuclear proposed changes (Refs. 1, 2) to Specifications 3.4.A.3, 3.4.A.4, and 3.4.D.2 of the Oyster Creek Technical Specifications (TS). The proposed change to reduce Average Planar Linear Heat Generation Rate (APLHGR) limits when a redundant Core Spray loop is out of service would ensure 10 CFR 50.46 criteria are met for each action statement of the applicable Limiting Condition for Operation-(LCO). Also, GPUN proposed clarifications to the associated bases to explain the existing seven day romedial action requirement when one Core Spray loop is declared inoperable. Pending NRC Staff approval, GPUN changed operating procedures to implement these more restrictive remedial actions as proposed.

By letter dated March 29, 1991, the NRC staff stated:

"This proposed change, however, does not address the concern ruised by the currently existing LCO that allows reactor operation up to a period of 7 days with only one operable core spray system. It should be emphasized here that a break in the pipe between reactor vessel and the core spray check valve in one loop while the other loop is inoperable results in complete loss of safety function, and has the

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potential to lead-to an unmitigated (Loss-of-Coolant Accident) LOCA. In the associated bases of the TS, the licensee attempted to justify continued use of the existing Lc0 by relying on the argument that the probability of a pipe break between the reactor vessel and the core spray check valve in the operable core I spray loop (approximately 28 feet of 6 inch pipe) I compared to the total pipe in the reactor coolant pressure boundary is very emall. The low probability

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1 argument that the licensee used to address tnis particular concern is not acceptable. This is because '

plant operation with an entire core spray loop out of j service does not meet the staff position that i operation should not continue with ECCS equipment out of service unless the remaining ECCS configuration is <

capable of limiting the consequences of any LOCA (without-an assumed additional single failure) to less than the consequsnees of the licensing basis LOCA.

During a conference call on 4/18/91, GPUN discussed with the NRC staff the reasons for the proposed change to the TS. Briefly, the original licensing basis for Oyster Creek established one main and one booster pump from one core spray loop providing_the required core cooling flow post LOCA. Further, seven days were allowed to restore an inoperable core spray loop, because each loop contained a redundant main and booster pump. Modifications were made in 1975 to power one set of redundant pumps in each Core Spray loop by each diesel generator (DG). This was done to correct single failure vulnerabilities, especially, the case of a Core Spray line break and the failure of a DG, These modifications were described initially in our letter dated 7une 24, 1975, Finfrock (JCP&L) to Lear (NRC) which addressed License condition 2.D.1 incorporated by Amendment No. 8. Although this scenario was explicitly considered in establishing physical plant changes we did not believe a change to the TS remedial action was necessary nor did the NRC Staff require it.

Currently, GPUN has demonstrated that one main and one booster pump-from one loop, and one main pump from the other loop provides the required flow to meet 10 CFR 50.46 acceptance criteria. With one loop inoperable, a 10%

reduction in APLHGR limits and flow from the other Core Spray loop (one main and one booster pump) would still provide the required flow during the seven day allowed outage time.

The existing' Oyster Creek TS allows reactor operation for seven days with one Core Spray loop inoperable providing the remaining loop has no inoperable components. This TS does not consider a break in the operable core Spray loop piping concurrent with the inoperable Core Spray loop.

The TS does consider, however, a single failure within the Core Spray operable loop and provides for this single failure concurrent with a break i in other piping systems which form the reactor coolant pressure boundary.

Therefore, the current Oyster Creek TS has a different basis from that whien is now being suggested by the NRC staff.

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In summary, the proposed TS addresses the original NRC concerns for meeting flow requirements when one Core Spray loop is operable. GPUN has implemented these restrictions even though the TS does not reflect them.

We are not proposing a change to the remedial action for an inoperable loop. We consider this action to be reasonable and, in fact, the original licensing basis of the plant.

The postulation of a pipe break in the operable Core Spray loop concurrent with the other loop inoperable represents a new license requirement.

Since this licensing basis change would be an issue with or without consideration of our proposed TS, we recommend that this issue be addressed separately by the NRC Staff. GPUN is examining the core damage frequency contribution of Core Spray line breaks separate from other LOCAs in the Individual Plant Examination (IPE). The results from this analysis can provide a technical basis for evaluating this issue via our IPE submittal.

In order to facilitate the correction of deficienclea in the current TS, please issue the TS amendment with the revised enclosed pages. These pages include changes from the con.pletion of a 13R modification to the Automatic Depressurization System logic. These changes are editorial in nature as defined in SlFR7744,Section I.C.2.e.(i), and therefore have no effect on the safety evaluation justifying the proposed amendment or on the corresponding no significant hazards consideration conclusions. In order to avoid confusion, we are submitting TSCR 160, Rev. 2, which supercedes in its entirety our previous submittal (Ref. 2). If you prefer to discuss this matter further, please contact Mr. Michawl Laggart, Corporate Licensing Manager.

neerely, /

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3arton

({/e' resident Oyster Creek and Director JJB/DJ/ pip cc Administrator, Region 1 Senior NRC Resident Inspector Oyster Creek NRC Project Manager