ML20126A898

Responds to NRC Telcon Request for Addl Info on Design Rept for Station Blackout/Electrical Safeguards Upgrade Project, Transmitted Via Util 901127 & s.Bldg D5/D6 Designed to Preclude Postulated Fire Exhaust

ML20126A898
Person / Time
Site:	Prairie Island
Issue date:	12/15/1992
From:	Parker T NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
TAC-M80659, TAC-M80660, NUDOCS 9212210289
Download: ML20126A898 (3)

Text

a Northern States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401 1927 Telephone (617) 33055CV)

December 15, 1992 10 CFR Part 50 Section 50.63(c)(d)

U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 PRAIRIE IS1AND NUCLEAR CENERATING PLANT Docket Nos. 50-282 License Nos. DPR 42 50-306 DPR 60 Reply to a Request for Information on Design Report for the Station Blackout / Electrical Safeguards Upgrade Project (TACd40s. M80659/80660)

References:

1) Letter from Thomas M Parker, Northern States Power Compt.ny, to U S Nuclear Regulatory Commission dated November 27, 1990 titled " Design Report for the Station Blackout / Electrical Safeguards Upgrade Project"

2) Letter from Thomas M Parker, Northern States Power Company,to U S Nuclear Regulatory Commission dated Deccaber 23, 1991 titled " Design Report for the Station Blackout / Electrical Safeguards Upgrade Project,a Revision 1 On November 27, 1990 we submitted for NRC Staff review the Design Report (Reference 1) for our project to add two safeguards emergency diesel generators, to upgrade the safeguards electrical distribution system, and to upgrade the #121 cooling water pump to become a. swing safeguards pump.

In response to various requests for additional information from the Staff, we submitted for NRC Staff review Revision 1 of the Design Report (Reference 2).

On November 30, 1992, a conference call between NRC Staff and NSP personnel was held in order that the Plant Systems Branch reviewers might better understand our design. This letter provides a written response to the following request for information: Describe the HVAC system arrangements which prevent an " air contamination abnormality" associated with one diesel generator, such as a fire, from causing inoperability of the other diesel

-generator.

RESPONSf, The Prp gggD,6Buildinghasbeendesignedandarrangedtoprecludeengine 9212210289 921215 PDR ADOCK 05000282 g P PDR .

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b Nodhen1 States Power Company USNRC Decembe*r 15, 1992 Page 2 of 3 j exhausts, a postulated fire exhaust, or other air contaminants emanating from I one unit from causing an effect on the other unit. As described below, inlets  ;

are segregated from exhausts / outlets by both elevation and orientation to '

preclude air system contamination. See Design Report Figures- 4 2, 4 6, 4-7, and 4 8. .,

D/G Elgetrical Bu1} dine HVAC Systgg Fresh air inlet is on the north side of the D5 side of the D5/D6 Building and on the south side of the 06 side of the D5/D6 Building, both at the i 735' elevation with the corresponding exhausts to the atmosphere at the 755' elevation.

D/C Encine Room IIVAC System Fresh air inlets for both D5 and D6 engine rooms are on the wast side of i the D5/D6 Building at the -711' elevation, which is 44 feet below the various ventilation system exhausts, with the corresponding exhausts to the atmosphere at the 755' elevation.

D/G Radiator Cooling Fresh air inlets for the D5 engine radiators are on the west and north sides of the D5/D6 Building at the 718' elevation. Fresh air inlets for-the D6 engine radiators are on the west and south side of the D5/D6 Building at the 718' elevation, which is 37 feet below the various ventilation system exhausts. -The corresponding exhausts'to the atmosphere are at the 755' elevation.

D/G Encine Combustion Air Inlets.

Combustion air inlets to the engines. for both DS and D6 engines are located within the respective D5 or D6 radiator rooms,- The combustion air  ;

inlets to the engines share the same. source of air as1 described for the radiator cooling, so that the inlets are 37 feet below the various ventilation system exhausts.

D/G Encine Exhausta Each engine exhausts _ through the exhaust piping routed through each engine room up to-the exhaust stack at the1771' elevation. There is-one exhaust

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stack for each engine for a total:of four, Repeating, the D5/D6 Building has-been designed and arranged to preclude engine exhausts, a postulated fire exhaust, or other air contaminants emanating from one unitifrom causing an effect on the other unit. This clarification will be included in Revision 2 of the Design Report.

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l 14 rthern States Power Company USNRC December 15, 1992 Page 3 of 3 Picase contact us if you have any questions related to this response.

l})l\t s'in Tiomas M Parker Director of Nuclear Licensing Nuclear Generation c: Regional Administrator Region 111, NRC __

Senior Resident Inspector, NRC NRR Project Manager, NRC J E S11 berg

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