ML20077A893

Application for Amend to License DPR-35,revising Suppression Chamber Water Level Operating Range,Increasing & Revises Water Level Recorder Range in Response to Commitment from Insp 50-293/91-201

ML20077A893
Person / Time
Site:	Pilgrim
Issue date:	11/22/1994
From:	Boulette E BOSTON EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20077A897	List: BECO-94-128, Application for Amend to License DPR-35,revising Suppression Chamber Water Level Operating Range,Increasing & Revises Water Level Recorder Range in Response to Commitment from Insp 50-293/91-201 ML20077A899
References
BECO-94-128, NUDOCS 9411280134
Download: ML20077A893 (4)

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10CFR50.90 .

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Boston Edison Pdgrim Nuclear Power Station l Rocky Hdi Road Plymouth _. Massachusetts 02360 j

E. T. Boulette PhD Senior Vice Preedent - Nuclear November 22, 1994 BECo Ltr. #94- 128 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Docket No. 50-293 License No. OPR-3_5 Proposed Change to Technical Specifications Suppression Chamber Water Level Boston Edison Company proposes the attached changes to Appendix A of Operating License No.

DPR-35 in accordance with 10CFR50.90. This proposed change revises the suppression chamber water level operating range, increasing it 2, and revises the water level recorder range in response to a commitment from inspection 91-201 (BECo Letter dated March 10,1992).

The requested change is described in Attachment "A" The revised Technical Specification pages are in Attachment "B". Attachment "C" provides the existing pages marked-up to show the proposed change.

We request a review of this change as soon as reasonably possible. This proposed change will allow the cperators greater maneuvering flexibility in the operation of Pilgrim Station.

/ ~3 C?r StotdM1 E. T. Boulette, PhD l

Commonwealth of Massachusetts)

County of Plymouth)

Then personally appeared before me, E. T. Boulette, who being duly sworn, did state that he is Senior Vice President - Nuclear of Boston Edison Company and that he is duly authorized to execute and file the submittal contained herein in the name and on behalf of Boston Edison Company and that the statements in said submittal are true to the best of his knowled e d belief.

My commission expires: MAR 4 - 1999 [// bl -

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1 cc: ' Mr. Rf Eaton, Project Manager Division of Reactor Projects -I/II Mail Stop: 14D1

,U. S. Nuclear Regulatory Commission 1 White Flint North 11555 Rockville Pike Rockville, MD 20852 U.S. Nuclear Regulatory Commission Region 1 475 Allendale Road King of Prussia, PA 19406 Senior Resident inspector Pilgrim Nuclear Power Station Mr. Robert M. Hallisey, Director Radiation Control Program Center for Communicable Diseases Mass. Dept. of Public Health 305 South Street Jamaica Plain, MA 02130 i

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Attachment A to BECo Letter 94-J23 Page 1 of 2 Proposed Cha_n,qe This proposed change to Section 3.7.A.1.m and its associated bases increases the Suppression Chamber (Torus) water level operating range from -6 to -3 inches to -6 to -1 ir'ches. The downcomer submergence is correspondingly revised from 3.0 - 3.25 feet to 3 feet - 3 feet 5 inches. This represents an increase of 2 inches. Also Table 3.2.F for the recorder range for the Suppression Chamber water level is revised from 0-32 inches to -7 to +7 inches.

The specific changes are identified by change bars in the margins of the proposed pages in Attachment "B, and by the marked-up current Technical Specification pages in Attachment "C".

Reason for Chanae in our March 10,1992 response to the Systems Based instrumentation and Control Inspection No. 50-293/91-201 (NRC letter dated January 6,1992), we committed to evaluate the feasibility of increasing the water level operating range. All necessary calculations have been completed and we have determined the torus water level operating range can be increased by 2 inches. This change refiacts the inspection commitment.

Increasing the operating range for the Suppression Chamber water level will allow plant operators greater maneuvering flexibility while maintaining a sufficient margin of safety. The current 3 inch range for the torus water level requires frequent operator manipulations, (filling or draining), especially during testing of Emergency Core Cooling Systems. Increasing the range to 5 inches will reduce the manipulations plant operators are required to make to maintain the appropriate water level.

The level transmitters were replaced with a smaller span (14 inches) for better accuracy since accuracy is related to span. The recorder scale was replaced due to this change.

Safety Evaluation and Determination of No Sianificant Hazards Considerations The Code of Federal Regulations (10CFR50.91) requires licensees requesting an amendment to provide an analysis, using the standards in 10CFR50.92, that determines whether a significant hazards consideration exists. The following analysis is provided in accordance with 10CFR50.92 for the proposed amendment to increase the Suppression Chamber water level operating range by 2 inches.

1. The operation of Pilgrim Station in accordance with the proposed amendment will not involve a significant increase in the probability or consequences of an accident previously identified.

The probability of an accident is not increased by this proposed change because there is no relation between the Suppression Chamber water level operating range and the probability of an accident.

The consequences of an accident previously identified are not increased. The Suppression Chamber is an accident mitigating device. Increasing the water level operating range has been analyzed and does not significantly increase the structural loads and the calculated stress levels remain within Mark i Acceptance Criteria.

Attachment A to BECo Letter 94,128 Page 2 of 2 We~ have reviewed the FSAR Containment Analyses and concluded that the safety margin is not affected. An increase in water level enhances the Suppression Pool's ability to mitigate an accident by providing more water for use by emergency cooling systems. The higher water level increases the heat sink capabilities resuiting in lower torus water temperatures from steam blowdowns. There is a minor reduction in the free air volume of the torus which has a negligible effect on containment post accident pressures. Therefore, there is no significant increase in the probability or consequences of an accident previously identified.

The change in water level recorder range does not involve an increase in the probability or consequence of an accident because the new recording range accounts for instrument loop uncertainties and is thus more conservative than the previous range.

2. The operation of Pilgrim Station in accordance with the proposed amendment will not create the possibitry of a new or different kind of accident from any accident previously analyzed.

An increase in the Suppression Chamber water level operating range does not create a new or different kind of accident from any accident previously analyzed because the Suppression Chamber is an accident mitigating device. The Suppression Chamber serves as the heat sink for any postulated transient or accident condition when the primary heat sink (main condenser) is unavailable and as a source of water for the Core Standby Cooling Systems. The structural affects of the increase in water volume have been analyzed and do not significantly effect the Mark I containment loads.

Revising the water level recording range is more conservative than that previously used and does not create the possibility of a new or different kind of accident.

3. The operation of Pilgrim Station in accordance with the proposed amendment will not involve a significant reduction in the margin of safety.

Operation with an increased Torus water level does not affect the structure and attached piping of the Pilgrim Suppression Chamber and does not significantly affect the calculated stress levels; therefore, there is no significant reduction in the margin of safety.

The change in the water level recording range is due to replacing the transmitter with a smaller span. The change from 0 to 32 inches to -7 to +7 inches enhances resolution and accuracy of the water level instrument loop.

l This proposed change has been reviewed and approved by the Operations Review Committee and l reviewed by the Nuclear Safety Review and Audit Committee.

l Schedule of Chance I

This change will be implemented within 30 days following BECo's receipt of its approval by the l Commission. l l

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