ML20011F619

Forwards Analysis of Small Steamline Break Performance W/O Low Pressurizer Pressure Safety Injection North Anna Units 1 & 2 & Proposed Amends to Licenses NPF-4 & NPF-7 Re Rupture of Main Steam Pipe Analysis

ML20011F619
Person / Time
Site:	North Anna
Issue date:	02/26/1990
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20011F620	List: ML20011F619 ML20011F622 ML20011F623
References
90-046, 90-46, NUDOCS 9003070047
Download: ML20011F619 (3)

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VINGINIA Et,ECTHIC ANI) POWEH COMi*ANY Hicuuoxu,VinasutA caces February 26, 1990 United States Nuclear Regulatory Commission Serial No.

90 046 Attention: Document Control Desk NL&P/JYR:

Washington, D.C. 20555 Docket Nos.

50-338 50 339 i

License Nos. NPF-4 NPF-7 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY l

NORTH ANNA POWER STATION UNITS 1 AND 2 L

RUPTURE OF A MAIN STEAM PIPE PROPOSED OPERATING LICENSE AMENDMENT i

Licensee Event Report (LER) No. 89 018 00 identified that the instrument loop uncenalnty associated with the low pressurizer pressure safety injection setpoint may i

exceed the margin between the setpcint assumed in the accident analysis and the actual setpoint value under adverse environment conditions. The instrument loop uncertainty in an adverse environment is sufficiently large such that safety injection initiated by Mw pressurizer pressure could not be assured. The existing rupture of a main steam pipe analysis takes credit for low pressurizer pressure safety injection for certain small steam line break scenarios.

As noted in LER 89 018 00, a formal analysis was performed in which no credit was taken for low prescurizer pressure safety injection. This analysis confirms that other sources of automatic safety injection provide adequate protection when required, or that no safety injection is necessary.

During our review of the instrument loop uncertainty associated with LER 89-018-00, it was determined that the probability of malfunction of the low pressurizer pressure safety injection had increased, and hence, an unreviewed safety question existed as defined by 10 CFR 50.59. Accordingly, our analysis which shows that low pressurizer pressure safety injection is not required for small steam line breaks is being submitted for NRC approval per 10 CFR 50.59(c); along with a request for the appropriate license amendment per 10 CFR 50.90. Attachment 1 is a copy of our aforementioned analys"s and Attachment 2 is our proposed amendment to the operating licenses for North

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Anna Units 1 and 2.

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This request'has been reviewed and approved by the Station Nuclear Safety and Operating Committee, it has been determined that the proposed change does not constitute a significant hazard as defined in 10 CFR 50.92. The basis for our

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determination of no significant hazard is provided as Attachment 3.

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.Very truly yoijrs,.

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-W. L Stewart Senior Vice President - Nuclear

' Attachments l

1.

Analysis of Small Steamline Break Performance Without Low Pressurizer Pressure Safety injection, North Anna Units 1 and 2 2.

Proposed North Anna Units 1 and 2 Operating License Amendments 3.

Significant Hazards Determination cc:

U.S. Nuclear Regulatory Commission Region ll

- 101 Marietta Street, N.W.

Suite 2900 Atlanta, Georgia 30323 Mr. J. L. Caldwell NRC Senior Resident inspector North Anna Power Station t

Commissioner Department of Health Room 400 109 Governor Street Richmond, Virginia 23219 I

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COMMONWEALTHOFVIRGINIA )

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COUNTYOFHENRICO

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The foregoing document was acknowledged before me, in 'and for the County and Commonwealth aforesaid. today by W. L. Stewart who is Senior Vice President - Nuclear, of Virginia Electric and Power Company.

He is duly authorized to execute and file the foregoing document in behalf of that Company, and the statements in the document are true to the best of his: knowledge and belief.

Acknowledged before: me this

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My Commission Expires:

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