ML19323C625

Forwards Inputs on Facility Fire Protection Review,Items 3.2.1 & 3.1.1B Re Fire Detection Sys for Drywell Detectors & Upgrading Existing Sys

ML19323C625
Person / Time
Site:	Monticello
Issue date:	05/02/1980
From:	Randy Hall BROOKHAVEN NATIONAL LABORATORY
To:	Ferguson R Office of Nuclear Reactor Regulation
References
NUDOCS 8005160402
Download: ML19323C625 (3)

Text

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800516n 40L BROOKHAVEN NATIONAL LABORATORY ASSOCIATED UNIVERSITIES, INC.

Upten. New Ycrk 11973 Department of Nuc!ect Energy , (516) 345-2144 May 2, 1980 i

Mr. Robert L. Ferguson Chemical Engineering U.S. Nuclear Regulatory Commission Washington, D.C. 20555 RE: Monticello, Fire Protection Review, Items 3.2.1(1) and 3.1.1B(2)

Dear Bob:

Attached are our inputs on items 3.2.1(1), Fire Detection Systems -

Drywell Detectors, and 3.1.1B(2), Fire Detection Systems - Upgrade Existing Systems for the Monticello plant.

Respectfully yours,

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Robert E. Hall, Group Leader Reactor Engineering Analysis i REH:EAM:sd l attachment cc.: W. Kato wo/att.

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MONTICELLO Fire Protection Review Item 3.2.1(1) - Fire Detection Systems - Drywell Detectors Item 3.2.1(1) of the Monticello SER indicates that the utility will evaluate the need for early warning fire detection in the drywell.

By letter dated February 29, 1980 Northern States Power Company responded to this item with the results of their evaluation. They indicated that:

The drywell is normally inerted with nitrogen whenever the reactor is in the run mode. Technical Specifications allow primary containment to be deinerted for a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period before and after a plant shutdown. De-inerting the drywell is only done when drywell entry is desired. Nomally this is only done during refueling outages.

The evaluation of the need for fire detectors in the drywell was completed by the Bechtel Power Corporation. As a result of this evaluation the need for detectors in the drywell was not demonstrated as being effective. The evaluation concluded that:

1. Fire detectors won't pick up incipient fires due to the large amount of air movement in this area.

2. There is a possibility that spurious fire detector actuation may be a problem during nomal plant operation. This would subject the plant to unnecessary shutdowns to investigate potential fires.

3. Large fires in the drywell would be detectable by other means, i.e.,

containment pressure, temperature or equipment alanns.

Based on these points, the licensee has concluded that fire detectors are not necessary in the drywell.

The original concern stated in the SER indicated that an unmitigated lube oil fire in the drywell could generate a sufficient amount of heat to damage elec-trical cabling which may affect the plant's shutdown capability. Because of this, the lack of fire detectors to give early warning of an incipient fire condition was considered inadequate. The licensee's conclusion that detectors are not necessary in this area was based largely on the operational character-istics of smoke detectors including the potential problems of sensitivity and false alarms associated with this type of installation.

The licensee's response on this item is considered unacceptable. If it can be shown that a fire in the drywell area will not affect safe shutdown capability the original concern will be mitigated and detectors will not be required. If it cannot be demonstrated, however, that a fire in the drywell will not affect safe shutdown capability, the original concern still remains and early warning detection in the drywell should be provided. We recommend that fire detectors be installed; the choice of fire detectors in this area should be carefully evaluated in order to determine the best type (s) of detectors which will pro-vide reliable, trouble free, early warning detection.

Item 3.1.1B(2) - Fire Detection Systems - Upgrade Existing Systems Item 3.1.1 was addressed in our input to you on February 13, 1980. This re-sponse is directed only on part B2.

Item 3.1.1B(2) of the Monticello SER indicates the licensee's proposal to up-grade the existing fire detection systems in the areas listed below by provid-ing electrical supervision and remote alarm capability.

Cable Spreading Room Standby Gas Treatment System Room Switchgear Areas Intake Structure MG Set Room By letter dated April 2,1980 the licensee responded to this item. They indicated that the systems were upgraded by providing supervision and remote alarming in accordance with NFPA 72D. The details of the fire alarm system was previously described in their letter of December 27, 1979.

The licensee's submittal also indicated that the existing fire detectors and the new fire detectors will be in-situ tested to assure the capability of the detectors as installed to respond to a fire in the early stages of growth.

The licensee's description of the system upgrading as referred to by SER item 3.1.1B(2) to provide electrical circuit supervision and remote alarm capabil-ity is considered acceptable. Tne licensee has not, as yet, submitted any information on the in-situ testing they have proposed to undertake to demon-strate the adequacy of the installed detectors. Upon receipt of this material the adequacy of the detection system to provide early warning will be evalu-ated.

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