ML19269B783

Responds to NRC 780921 Rejection of Design Criteria for Installation of Ionization Detectors in Areas Containing Both Combustibles & Equipment/Cables Required for Safe Shutdown.Requests Approval of Schedule to Make Related Mods

ML19269B783
Person / Time
Site:	Rancho Seco
Issue date:	11/14/1978
From:	Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Reid R Office of Nuclear Reactor Regulation
References
NUDOCS 7811170117
Download: ML19269B783 (2)

Text

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QSMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT C 6201 s Street Box 15830, Sacramer,to, California 95813; (916) 452-3211 November 14, 1978 Director of Nuclear Reactor Regulation Attention:

Mr. Robert W. Reid, Chief Operating Reactors, Branch No. 4 U. S. Nuclear Regulatory Conmission Washington, D. C.

20555 Dccket No. 50-312 Rancho Seco Nuclear Generating Station, Unit No.1

Dear Mr. Reid:

In your September 21, 1978 letter to the District you stated that the District's design criteria with respect to installing ionization detectors only in areas containing both combustibles and equipment / cables required for safe shutdown is not in conformance with the provisions of BTP 9.5-1 Appendix A, and therefore not acceptable.

The District's design criteria was based on the assumption that a fire which could damage equipment / cable required for safe shutdown and cooldown required prompt fire detection, in the form of ionization detectors.

However, other equipment / cables that are safety related but are not required for safe shutdown and cooldown were not protected since their loss in a fire would not prevent safe shutdown and cooldown. This design criteria was based on Section IV A-2 of Appendix A to Branch Technical Position APCSB 9.5-1 " Guidelines for Fire Protection for Nuclear Power Plants Docketed Prior to July 1,1976" which stated that "The overall Fire Protection Program should be based upon evaluation of potential fire hazards throughout the plant and the effect of postulated design basis fires relative to maintaining ability to perform safety shutdown functions and minimize radioactive releases to the environment."

The District's proposed design accomplishes this and therefore is in agreement with Appendix A of Branch Technical Position 9.5-1.

However, the installation of the ionization detectors in all areas that contain combustibles and safety related equipment would improve the design and add a degree of conservative margin.

Therefore, as requested in your Septembar 21, 1978 letter, the District will have installed in all areas that contain combustibles and safety related equipment / cable ionization y

D detectors except for fire areas 37, 38, 69 and 71.

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Mr. Robert W. Reid November 14, 1978 proposed alternative protective measures for these areas which you accepted in your September 21, 1978 letter.

This agreement to install ionization detectors in all areas that contain safety related equipment and/or cable will require additional modifications that were not considered in the District's February 1,1978 letter to the NRC detailing the schedule that would be followed for install-ation of Fire Protection Modifications.

This letter was used as a reference in providing the schedule in the NRC's Fire Protection Safety Evaluation attached to Amendment No.19 for item 3.1.37 which requires this work to be completed by the end of the 1978 refueling outage.

However, this new commitment will require installing additional detectors in Fire Areas 34, 35, 39, 40, and 42.

The 1978 refueling outage is scheduled to start November 15, 1978 and be completed December 6,1978.

There is no way possible at this time to purchase the necessary equipment, have it installed and tested by the end of the 1978 refueling outage.

Therefore, the District requests that a schedule to have these detectors installed as soon as possible but not later than the end of the core four refueling which is scheduled for late 1979 or early 1980 be accepted by the NRC.

Sincerely yours,

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J. J. Mattimoe Assistant General Manager and Chief Engineer O

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