ML20126B682

Proposed TS Change 176 to License DPR-36,modifying TS 3.19 & 4.6 for Consistency W/Change in Normal Operating Position of LPSI motor-operated Isolation Valves from Closed to Open

ML20126B682
Person / Time
Site:	Maine Yankee
Issue date:	12/15/1992
From:	Frizzle C Maine Yankee
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20126B685	List: ML20126B682 ML20126B691
References
CDF-92-164, MN-92-128, NUDOCS 9212220173
Download: ML20126B682 (4)

Text

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December 15, 1992 HN-92-128 CDF-92-164 Proposed Change No. 176 UNITED STATES NUCLEAR REGULATORY COMMISSION Attention: Document Control Desk Washington, DC 20555

References:

(a) License No. DPR-36 (Docket No. 50-309)

(b) USNRC Letter to all LWR Licenses dated February 23, 1980 (c) MYAPCo letter to USNRC dated March 9, 1981 (FMY-81-37) d) USNRC Letter to MYAPCo dated April 20, 1981 e) MYAPCo letter to USNRC dated July 6, 1981 (fHY-81-lGO) f) USNRC Letter to MYAPCo dated July 10,1%1 g) USNRC Letter to HYAPCo dated August 24, 1984 (h) MYAPCo Letter to USNRC dated riarch 23, 1992 (MN-92-24)

Subject:

Proposed Technical Specificatic: Change No.176 - Low Pressure Safsty injection System Periodic Ter. ting Gentlemen:

Maine Yankee hereby submits, pursuant to 10 CFR 50.90, this application to amend sections of the Maine Yankee Technica? Specifications. This proposed change modifies Technical Specifications 3.19 and 4.6 to be consistent with the change in normal operating position of the low ;,ressure safety injection (LPSI) motor operated isolation valves (LSI-M-ll, 21 end 31) from closed to open. The proposed change is conservative in that additiora1 actions previously permittea if check valve barriers exceeded their leakage specification are eliminate 5. The. change would result in Maine Yankee specificetions becor 2 3 more consistent with standard CE Technical Specifications.

A description of the proposed changes and a summary of the Significant Hazards evaluation is presented in Attachment A. As discussed in the attachment, this change does not involve a significant increase in the probability or consequences of an accident previously evaluated, create the possibility of a new or different kind of accident from any accident previously evaluated, or involve a significant reduction in a margin of safety. Thus, based on this evaluation, it is concluded that there is reasonable assurance that operation of the Maine Yankee plant, consistent with the proposed Technical Specifications, will not impact the health and safety of the public.

Revised Technical Specification pages 3.19-2, 4.6-1, 4.6-2,4,6-3 and 4.6-5 are included as Attachment B.

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[ili!lllu til}(OC UNITED STATES NUCLEAR REGULATORY COMMISSION MN-92-128

Attention: Document Control Desk Page Two This proposed change has been reviewed and approved by the Plant Operation and Review Committee. The h Clear Safety Audit and Review Committee has also reviewed this submittal. A representativo of the State of Maine is being informed of this request by a copy of this letter.

We request that this proposed change be made effective within 30 days after i,

issuance.

Very truly yours, g

Charles D. Frizzle President and Chief Executive Officer WBD/ jag Attachments c: Mr. Thomas T. Martin Mr. E. H. Trottier Mr. Charles S. Marschall Mr. Clough Toppan STATE OF MAINE Then personally appeared before me, Charles D. Frizzle, who being duly sworn did state that he is President and Chief Executive Officer of Maine Yankee Atomic Power Company, that he is duly authorized to execute and file the foregoing request in the name and on behalf of Maine Yankee Atomic Power Company, and that the statements therein are true to the best of his knowledge and b ief.

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i ATTACHMENT A

] Qescription of Proposed Chanoes f Maine Yankee's low pressure safet injection system is desi ned to deliver i borated water to the reactor vessel to ffood and cool the core upon fepressurization i of the reactor coolant system following a loss-of-coolant accident. Two isolation

check valvos and a third thermal barrier check valve all located in the containment j building form the isolation barrier between the RCS and the low pressure piping of

the LPSI system. The motor operated valves (LSI-M-11, 21 and 31) are located outside

containment in the containment spray building.

1

! In the past, Maine D.nkee has operated with LSI-N-11, 21 and 31 shut providing

! an additional barrier between the RCS and the low pressure LPSI system. These valves served as a containment isolation barrier in response to industry EVENTS V accident concerns raised in Reference (b). These concerns were later resolved with the installation of a second isolation check valve and the inclusion of inservice leakage '

i testing requirements in the Technical Specifications, Refarences (c), (e), and (f).

The present Surveillance Specification 4.6.A.2.f requires -leak testing of the  !

check valve barriers defined in Specification 3.19. A.4. If Barrier (a) or Barrier i (b) is leaking greater than its respective specification, the reactor may be made or j remain critical for up to 30 days provided the affected ECCS line Motor Operated

, Valve remains closed. If both Barrier (a) and Barrier (b), in the same loop, are leaking greater than their respective specifications, the reactor shall not be made or remain critical for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

! This proposed change revisos the acceptance criteria of Specification 4.6.A.2.f i

to be consistent with the change in position of these valves by retaining the Condition 1 acceptance criteria as the surveillance test acceptance criteria and by deleting the Condition 2, 3 and 4 acceptance criteria. The Condition 4 additional i

action has been incorporated into the Specification 3.19.A.4 Remedial Action. In addition, the Exception associated with Specification 4.6.A.1.b has been deleted to be consistent with alignment of these valves in the open position. With the valves ,

, o)en, prohibitions on testing are no longer relevant since the valves will not be l slut due to check valve leakage.

Maine Yankee's Probabilistic Ris.t Assessment (PRA) indicates a slight reduction in core damage probability when operating with these valves open.

! for Specifications 3.19 and- 4.6 indicate the valves remain- Theshut present bases except - for

, surveillance testing. These basis section paragraphs are deleted by this pro)osed I

change as the valves are normally aligned in the open position consistent wit 1 the -

l PRA.

Sionificant Hazards Evaluation

! Maine Yankee has evaluated - these proposed changes to the Technical

' Specifications to s)ecifically address operation with LSI-M-II.- 21 and 31. open against the standarcs of 10 CFR S0.92, and have been determined not to involve a significant hazards consideration. These proposed changes do not:

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1.* Involve a significant increase in the probability or consequences of an accident previously evaluated. The FSAR accidents requiring ECCS actuation currently require active functions from an SIAS signal to eleven injection valves in order to inject water into RCS cold legs. The proposed change considers aligning valves LSI-M-ll, 21 and 31 in their

open position. By positioning the LSI valves open, the chances of single active failure is eliminated for these valves, system operation is simplified, and the probability of ECCS functioning properly on demand is improved.

The safety class boundary of the ECCS System will not be affected by the 4 proposed change. The current ANS 51.1/ ANSI 18.2 Standard requires two in-line check valves as the boundary between 50-1 and SC-2 for the RCS and ECCS interface. Periodic testing for each pressure boundary check valve is required. At Maine Yankee, this design requirement is met by three in- l line check valves. The first two check valves from the RCS are combined -

to form Barrier "A" and the third check valve forms Barrier "B". Leakage monitoring is required by Technical Specification 4.6.A.2.f. Also, PRA analyses conclude this configuration results in a slight decrease in core damage probability. Thus, the probability of an accident previously analyzed in the FSAR is aqt increased.

2. Create the possibility of a new or different kind of accident from any previously evaluated. No unanalyzed FSAR accident would be created by this valve alignment change. The postulated ECCS spillage in LOCA accidents would be unaffected. Containment isolation and system safety classification remain unchanged. The possibility of malfunctions in ECCS equioment and control circuits would be reduced principall oecause there would be fewer active components which could contribute a single active

, failures.

3. Involve a significant reduction in a margin of safety. The Maine Yankee leak test history on the barrier check valves provides a basis for discontinuing the use of the LSI M0Vs as backup barriers. The leakage data collected rince 1982 indicates that the check valves have not approached the Technical Specification 4.6 allowed leakage rates. This l data shows that the three series check valves are adequately providing the I

overpressure protection required by NRC.

By making the ECCS systems more passive, Maine Yankee is enhancing the probability of successfully mitigating the consequences of FSAR accidents.

Maintaining the injection valves in their open position ensures proper i system flow and improves the reliability of delivering water to the i unbroken RCS loops in a LOCA event. This alignment will not affect rates of spillage currently analyzed for FSAR accidents and thus the margin of safety is preserved.

Based on the discussion above, it is concluded that there is reasonable assurance that operation of the Maine Yankee plant, consistent with the proposed l Technical Specifications, will not endanger the health and safety of the public.

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