ML20214A276

Requests Withdrawal of Request for Exemption from 10CFR50, App R,Section III.G.2.b in Case of Emergency Diesel Generator Ventilation Exhaust Openings.In Lieu of Exemption, Util Requests NRC Review & Approval of Listed Encls

ML20214A276
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	05/08/1987
From:	Yundt C PORTLAND GENERAL ELECTRIC CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20214A279	List: ML20214A276 ML20214A294
References
GL-86-10, TAC-55831, TAC-63463, NUDOCS 8705190365
Download: ML20214A276 (3)

Text

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David W. Cockfield Vice President, Nuchar May 8, 1987 Trojan Nuclear Plant Docket 50-344 Licenso NPF-1

~ U.S. Nuclear Regulatory Commission ATTN: Document Control Dock Washington DC 20555

Dear Sir:

Exemption Roquests From Title 10 Code of Federal Regulations, Part 50 (10 CFR 50)

Appendix R Information relative to two 10 CFR 50 Appendix R oxomption requests submitted previously by Portland Conoral Electric Company (PCE) is contained horoin.

PCE has roovaluated the need for one of those exemptions and concluded that it is no longer necessary. The exemption roquest in question is for Fire Area T1, as described in PCE's October 16, 1986 submittal. That lottor contained a pro-posed reviolon to Section 5.2.3 of Topical Report PCE-1012 (Volume II), Fire Protection Plan - 10 CFR 50 f.ppendix R Review. Additional review of this incuo and discusolone with Mossrs. Stang and Chan of your staff, have confirmed that the emersoney diocol generator (EDC) exhaust openingo do satisfy the requiro-monts of Section III.C.2 of 10 CFR 50 Appendix R. Thorofore, we hereby withdraw our roquent for an exemption from Appendix R,Section III.C.2.b in the caso of the EDC ventilation exhaust openings.

In lieu of an exemption, in accordance with Conoric Lotter 86-10, Section 3.1.2 PCE roquesto Nuclear Regulatory Commission (NRC) staff review and approval of the adequacy of:

1. Attachment 1, Evaluation Concerning Sudden Closure of Both EDCo' Ventilation Exhaust Openings,

2. Attachment 2, description of an automatic sprinkler system installed to protect the EDC ventilation exhaust openings from an exposuro fire in the Turbino Duilding railroad bay, and

3. Attachment 3 excerpto from PCE-1012 (Volumo I), Firo Protection Plan -

Program Doncription, Sections ?.4.7.1, 3.4.7.5, and 3.4.7.6. Theco sections contain the firo hazards analysis of Fire Arono T1, TS, and T6. Thoso areno are tho 45-ft clovation Turbino Building railroad bay and EDC rooms.

8705190365 870508 PDR ADOCK 05000344 8{g F PDR

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D W Geriew-d BectricCoraxu1y Document Control Desk May 8, 1987 Page 2 Please note that Section 5.2.3 of the Appendix R Review report will not be revised as indicated in the October 16, 1986 lotter. The exemption request for Fire Area T1 will remain as indicated through Amend:.ent 1.

In regard to the second exemption request, Attachment 4 provides a description of the redesign of the water curtain between Fire Areas A4 and A4a. A fourth sprinkler head is to be added below the lowest cable tray.

This sprinkler head is planned to be installed by December 31, 1987, but in no case later than June 1988 per the NRC's letter of April 10, 1987 which addresses implementation schedules for fire protection modifications.

We would be pleased to discuss any questions or comments you may have regarding this information.

Sincerely, Ar Attachment c: Mr. John B. Martin Regional Administrator, Rvgion V U.S. Nuclear Regulatory Commission Mr. R. C. Barr NRC Resident Inspector Trojan Nuclear Plant Mr. David Kish, Director State of Oregon Department of Energy

Trojan Nuclear Plant Document Control Desk Docket 50-344 May 8, 1987 License NPF-1 Attachment 1 EVALUATION CONCERNING SUDDEN CLOSURE OF BOTH EMERGENCY DIESEL GENERATORS' (EDGs) VENTILATION EXHAUST OPENINGS Although each EDC room is an independent fire area, an exposure fire in the Turbine Building railroad bay has the potential to cause exhaust paths for both EDGs to be secured by closure of their respective fire dampers.

A calculation of the EDG rooms with one exhaust path inoperable showed that temperatures reach an unacceptable level in minutes. However, there are conservatisms in the calculations which indicate response time for operator action is available. They are as follows:

1. The initial room temperature is assumed to be 116*F. This is only possible with the engines running for an extended period, at load, and in summer design conditions. This means that the fans would be running, which produce an outlet velocity of over 1200 f t/ min. It would have to be an extremely large fire plume to overcome the exhaust flow such that the temperature reaches the point at which the dampers shut.

2. All of the heating loads from the engine, generator, and exhaust piping to ambient are assumed to be instantaneous, which is not the case. Due to the mass of the engine, especially, it takes nearly 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of loaded running to approach those values.

3. No credit was given for increased airflow from the other fan due to pressurization of the room by the supply fan.

In any event, the approach followed was to prevent a fire in the train bay from escalating to the point that exhaust damper closures for redun-dant EDG rooms would occur. Suppression system actuation occurs at 135'F whereas the fire damper closure would not occur until 160*F or higher.

The location of the damper fusible links relativo to the sprinkler heads results in the heads sensing the increasing temperature first. There-fore, the fire would be extinguished prior to actuating damper closure.

As an added precaution, Plant Emergency Fire Procedures are being revised to requiro Operations personnel to verify EDG exhaust dampers open in the event of a fire in the Turbine Building railroad bay. These revisions will be completed by December 31, 1987.

In conclusion, the EDG fire areas meet the requirements of 10 CFR 50, Appendix A. General Design Criterion 3, Fire Protection, and 10 CFR 50, Appendix R.Section III.G.2.

DJM/mc/1120P