ML20215N893

Application for Amends to Licenses NPF-11 & NPF-18,revising Tech Specs to Lower MSIV Closure Signal from Reactor Pressure Vessel (RPV) Level 2 to RPV Level 1,per NUREG-0737, TMI Action Plan Item II.K.3.16.Fee Paid

ML20215N893
Person / Time
Site:	LaSalle
Issue date:	10/23/1986
From:	Allen C COMMONWEALTH EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
Shared Package
ML20215N895	List: ML20215N893 ML20215N910
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.K.3.16, TASK-TM 2292K, NUDOCS 8611100039
Download: ML20215N893 (5)

Text

v i% ' - ) One Fwst Nabonal Piara. Chcago, IEnois

%" Address Reply to: Post Omco Box 767 CheeDo, Illinois 60600 0767 October 23, 1986 i

Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulator Commission Washington, DC 2055

Subject:

LaSalle County Station Units 1 and 2 Proposed Amendment to Technical Specification for Facility Operating License Nos. NPF-ll and NPF-18

.MSIV Group I Isolation Signal to Level 1 from Level 2 NRC Docket Nos. 50-373 and 50-374

Dear Mr. Denton:

Pursuaat to 10 CFR 50.90, commonwealth Edison proposes to amend Appendix.A, Technical Specification, to Facility Operating License Nos.

NPF-ll and NPF-18. These changes are being submitted for your staff's review and approval. Attachment A provides the background and discussion for the proposed changes.

l. The proposed change is enclosed in Attachment B. The attached

! change has received both on-Site and Off-Site review and approval. We have reviewed this amendment request and find that no significant hazards consideration exists, our review is documented in Attachment C.

Commonwealth is notifying the State of Illinois of our request for this amendment by transmitting a copy of this letter and its attachments to the designated State Official.

In accordance with the provisions of 10 CPR 50.170, a fee remittance in the amount of $150.00 is enclosed.

Please address any questions you may have concerning this matter to this office.

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Mr. H. R. Denton October 23, 1986 Three (3) signed originals and thirty-seven (37) copies of this transmittal and its attachments are provided for your use.

Very truly yours, C. M. Allen Nuclear Licensing Administrator im Enclosure Attachments (A): Background and Discussion (B): Technical Specification Change to NPF-ll and NPF-18 (C): Evaluation of Significant Hazards Consideration cc: J. G. Keppler, Region III Resident Inspector - LSCS M. C. Parker - State of IL (IDNS)

SUBSCRIBED AND to befogq his day of {10 tol , 1986

-3 - OL(h Notary ensiic y 2292K

ATTACHpBNT A BACKGROUND AND DISCUSSION REFERENCES (1): 10 CFR 50.62, ATWS Rule (2): Modification 1-2-84-61 (3): QUAD l-83-008, Analysis Report-MSIV Design Modification I (4): NURBG-0737, TMI Action Plan Requirements (5): P&ID M-66 sheets 1,2,3, and 4.

(6): SIL No. 367, RPV Water Level Setpoint for MSIV closure (7): 10 CFR 50.49, EQ Rule BACKGROUND:

The Group 1 (Main Steam Isolation Valves and drains) isolation closure signal on lower reactor vessel level is presently at RPV Level 2 (-50 inches). BWR/6 reactors have a Main Steam Isolation Valve (MSIV) closure at RPV Level 1 (Reference (6)).

The objective of Item II.K.3.16 of reference (4) is to reduce the potential challenges and failures of SRVs. In response to this requirement, the BWR Owners Group submitted the results of a feasibility study and evaluation of various actions and modifications which might reduce the challenges and failures of SRVs. One of these actions was a recommendation to lower the MSIV closure signal from RPV level 2(-50 inches) to RPV level 1(-129 inches).

In reference 1, the NRC specified requirements to reduce the risk from postulated ATWS events. Lowering the main steam isolation valve closure signal from RPV level 2 to RPV level I will assist in mitigating postulated ATWS events.

DISCUSSION To justify the setpoint change, an analysis of the impact on the safety analysis was performed (reference (3)). LOCA analyses for three break sizes were performed. To support this change of MSIV closure setpoint the Technical Specifications must be revised as shown on Attachment A.

The Group 1(MSIVs and main steam drains) isolation from reactor vessel level has been changed from level 2 to level 1. All other requirements (surveillence intervals, action statements, etc.) remain the same for the reactor vessel level instruments. In addition, the instrument air i

i

~(nitrogen) supply to the MSIVs must also remain available to reactor level 1 since the MSIVs fail closed on loss of air. The valves associated with this instrument nitrogen supply are: two(2) air compressor suction valves, 1(2)IN001A&B; two(2) air compressor dryer blowdown valves, 1(2)IN074, 1(2)IN075; and one(1) air compressor discharge valve, 1(2)IN017. The instrument nitrogen valves and their arrangement are shown on the drawings listed in reference 5. The design modifications as described above will maintain condenser availability for a longer period of time during power coastdown. This allows more energy to be released to the main condenser (and removed from the primary containment). The net effect is added manual response time for the reactor operator and a lesser challenge to the integrity.of the suppression pool structures. By removing this energy, the reactor system safety is improved from the standpoint of reducing SRV challenges (and the potential for stuck open SRVs), and mitigating (along with other systems) the consequences of ATWS events. Therefore based on the above discussion and on the analysis performed in reference 3 lowering of the MSIV isolation setpoint to level I has insignificant impact to UPSAR chapter 6 and 15 events in terms of vessel pressure, core inventory, and fission product release. This change to the Technical Specifications will therefore have no significant reduction in the margin of safety.

Basis Figure B 3/4 3-1 has'been changed; l

l 1) to reflect the lowering of the MSIV isolation setpoint.

l

2) to correct admin.49trative errors, and

3) to eliminate the instrument manufacturers listing from the drawing. Information concerning the instrument manufacturers is readily obtainable from other controlled plant documents, such as, the architect engineers instrument listing and the station procedures.

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1 ATTAC19ENT B PROPOSED CHANGE TO APPENDIX A TECHNICAL SPECIFICATIONS TO OPERATING LICENSE REVISED PAGES:

NPP-ll NPF-18 3/4 3-11 3/4 3-11 3/4 3-15 3/4 3-15 3/4 3-18 3/4 3-18 3/4 3-20 3/4 3-20 Insert Insert 3/4 6-26 3/4 6-29 B 3/4 3-7 B 3/4 3-7 l

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