ML20211A217

Part 21 Rept Re Outside Containment Flooding Analysis Calculation.Initially Reported on 860407.Calculation Revised to Evaluate Lines Previously Exempted from Analysis & Flood Barriers Constructed Around Listed Areas

ML20211A217
Person / Time
Site:	Beaver Valley
Issue date:	10/07/1986
From:	Garfinkel P STONE & WEBSTER ENGINEERING CORP.
To:	Taylor J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
References
REF-PT21-86-333-000 PT21-86-333, PT21-86-333-000, TAC-62939, NUDOCS 8610150031
Download: ML20211A217 (3)

Text

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STONE 6 WEBSTER ENGINEERING CORPORATION 245 SUMMER STREET, BOSTON. M ASSACHUSETTS ADDRESS ALL CORRESPONDENCE TO P.O. BOX 2325. BOSTON. MA 02107 W U, TELEX 94 0001 R et C NSrRUCTioN C ' "" "'"~ "" "I ."I.Irion.

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Mr. James M. Taylor October 7, 1986 Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, DC 20555 NOTIFICATION OF DEFECT BEAVER VALLEY POWER STATION UNIT 2 DUQUESNE LIGHT COMPANY Stone & Webster Engineering Corporation (SWEC), pursuant to the provisions of 10CFR21, hereby provides notification of a " defect" concerning the Beaver Valley Power Station Unit 2, principally owned by Duquesne Light Company (DLC), and for which SWEC is providing both engineering and construction services.

In accordance with the reporting requirements of Section 21.21(b)(3), the following information is submitted:

1. Name and address of the individual informing the Commission:

Mr. P. Garfinkel Director of Engineering Stone & Webster Engineering Corporation P.O. Box 2325 Boston, MA 02107

11. Identification of the facility, or the basic component supplied for such facility, which contains a defect:

Beaver Valley Power Station Unit 2 Outside Containment Flooding Analysis Calculation lii. Identification of the firm constructing the facility or supplying the basic component which contains a defects Basic component supplied by Stone & Webster Engineering Corporation, Boston, Massachusetts iv. Nature of the defect and the safety hazard which could be created:

The Engineering Assurance Hazards Program Audit identified an unjustified assumption in the design basis of the outside containment flooding analysis. Project Technical Procedure 2BVM-114, " Essential Systems, Components, and Instrumentation 8610150031 861007 DR ADOCg o900 g ll}

f ,

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[ Required for Safety Functions," establishes the design basis for

evaluating the flooding effects of postulated piping failures required by Standard Review Plan Section 3.6-1. A statement in the flooding design basis assumed that 100 percent of process fluid above 2120F will flash ' to steam as it flows out of a double ended pipe rupture. This assumption was not conservative

. because an analysis of a main feedwaer line rupture demonstrated that only 25 percent of the process fluid will flash to steam.

l The analysis of a main feedwater line rupture in the Service

? Building conservatively assumes that the volume of the condenser hotwell is deposited on the 780'-6" floor. The resulting flood height in ' the plant vital switchgear area (Service Building elevation 730'-6") submerges several essential components including the 480 V vital switchgear cabinets and jeopardizes safe shutdown capability. This represents a major reduction in the degree of protection provided to the public health and 4 safety and could create a substantial safety hazard.

1 i v. Date on which information of such defect was obtained

! October 7, 1986 4

vi. In the case of a basic component which contains a defect, the number

-and location of all such components in use at, supplied for or being j supplied for facilities subject to the regulation

I Beaver Valley Unit 2 is , to date, the only project for which SWEC has applicable engineering and design responsibility determined to have this defect.

Should this information change, j this report will be amended accordingly.

I vii. Corrective action which has been taken). name of individual or organization responsible; and length of time taken- to complete the

actions i The outside containment flooding analysis calculation has been revised to evaluate lines previously exempted from analysis, I and Project Procedure 2BVM-114 was revised to correct' the j unjustified assumption in the design basis. To mitigate the flooding effects of a main feedwater line break in the Service j Building, the following construction changes are being implenented i

f o Flood barriers will be constructed around all Service Building vent duct floor penetrations at elevation 780'-6";

l o Four doors will be gasketed; i

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3 o Flood barriers will be installed around the bottom row of breakers in affected 480 V vital switchgear cabinets; and o A blowout panel will be relocated to mitigate flooding effects.

viii. Advice related to the defect that has been given to purchasers or licensees No other action apart from that specified above.

NRC has been previously advised of this problem by DLC Technical Audit No.

50 (Hazards Analysis Program) dated April 7, 1986, and which is referenced in NRC Inspection Report 50-412/86-23. Additionally, DLC provided ' NRC Region I with a notification pursuant to 10CFR50.55(e) on September 18, 1986.

If you require any further information, please contact Mr. R. B. Bradbury at (617) 589-1291.

44 P. Garfinkel Director of Engineering i

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