ML13308A646

Forwards Fire Protection Review Responding to Items 3,7 & 10 & Licensee .Automatic Power Backup Should Be Supplied for Fire Alarm Sys

ML13308A646
Person / Time
Site:	San Onofre
Issue date:	05/13/1980
From:	Hail R Brookhaven National Lab (BNL)
To:	Ferguson R Office of Nuclear Reactor Regulation
References
TAC-48143 NUDOCS 8005220512
Download: ML13308A646 (5)

Text

REGULATORYTNFORMATION DISTRIBUTION SYTEM (RIDS)

ACCESSION NBR:8005220512 DOCDATE: 80/05/13 NOTARIZED: NO DOCKET #

FACIL:50-206 San Onofre Nuclear Station, Unit 1, Southern Californ 05000206 50-361 San Onofre Nuclear Station, Unit 2, Southern Californ 05000361 50-362 San Onofre Nuclear Station, Unit 3, Southern Californ 05000362 AUTH,NAME AUTHOR AFFILIATION

HAILRE, Brookhaven National Laboratory RECIP.NAME RECIPIENT AFFILIATION FERGUSONfR,L, Assistant Director for Plant Systems

SUBJECT:

Forwards fire protection review responding to Items 3,7 & 10

& licensee 800123 Itr,Automatic power backup should be supplied for fire alarm sys, DISTRIBUTION CODE: A006S COPIES RECEIVED:LTR I ENCL j SIZE:.

TITLE: Fire Protection Information (After Issuance of OP, Lic,)

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL ACTION:

05 BC Ot W..,

4 4

INTERNAL: 0 1

1 02 NRC PDR I

1 09 I&

2 2

12 AUXIL SYS BR 2

2 14 PLANT SYS BR 5

5 19 WAMBACH 1

1 20 MURANAKAR 1

1 OELD 1

0 EXTERNAL: 03 LPDR 1

1 04 NSIC 1

1 22 ACRS 16 16 MAY 23 1980

31.

TOTAL NUMBER OF COPIES REQUIRED: LTTR ENCL

ULD f1~ UBROOKHAVEN NATIONAL LABORATORY ASSOCIATED UNIVERSITIES, INC.

Upton, New York 11973 Department of Nuclear Energy (516) 345-2144 May 13, 1980 Mr. Robert L. Ferguson Chemical Engineering U.S. Nuclear Regulatory Commission Washington, D.C. 20555 RE:

San Onofre, Fire Protection Review

Dear Bob:

The attached evaluation has been made at the request of Leo Derderian.

It involves our response to items 3, 7 and 10 and the licensee's letter of January 23, 1980.

Respectfully yours, Robert E. Hall, Group Leader Reactor Engineering Analysis REH:EAM:bf attachment cc.: W. Benaroya wo/att.

W. Kato M. Levine E. MacDougall 8005220 31.&

San Onofre Fire Protection Review Item 3 The fire suppression system power supplies should be automatically transferred to the on-site diesel generators upon loss of offsite power.

Response

The present design of the electric system at San Onofre, Unit 1 is such that upon loss of normal offsite power, manual actions are required to return power to the station (4i e., energization of the 4 kV buses) from either the alternate source of offsite power, or the onsite diesel generators. The time required to perform all manual actions, and verify the automatic actions, is approximately two minutes. If the main generator disconnect switch DC drive motor fails, the switch must be opened manually increasing the total time to seven minutes.

Once the 4 kV buses are energized, no additional manual actions are required to return the fire protection systems to service. Since under normal circumstances the fire protection system would only be out of service for approximately two minutes (seven minutes for worst case) and since no additional manual actions are required to restore the systems to service, the existing design is consider ed acceptable for supplying power to the fire protection systems following loss of normal pffsite power for the following reasons:

a. The fire water system at San Onofre Unit 1 will be interconnected to the Units 2 & 3 fire water system. Since the Units 2 & 3 diesel driven fire pump will automatically start on a low pressure demand signal regardless of the availability of offsite power, fire water pumping capabilitisfor Unit 1 will be available without performing any manual actions.

b. In the lube oil reservoir and conditioner area, the 480 volt room walls, the north wall of the turbine building, and the general area coverage is protected by a fusible link wet-pipe sprinkler system, in addition to the other systems in the area. As specified in a) above, fire pumping capabil ity is available so that given a complete loss of offsite power and a fire in this area, the sprinkler system would be available for fire protection even during the 2-7 minutes it would take to restore power to Unit 1.

c. For the areas where the combustible material is cable insulation (switch gear rooms and vital bus cabinet) the 2-7 minute outage of the fire pro tection systems is considered acceptable based on the fact that these areas involve slow burning, smoldering fires which would not cause a significant amount of damage during the short time period.

d. The area of the Station Service Transformers 2 & 3 involves a fire hazard associated with 2308 lb. of cable insulation and 534 gal. of oil.

The postulated fire is ignition and spillage of transformer oil from one of

.the two transformers (267 gal.)

The fire suppression system is intended

to protect surrounding cables and other equipment in the vicinity of the transformers. Since this is an open area, it has been determined that the unmitigated fire occurring for a short duration (7 minutes) is not expected to damage these cables and equipment. It has also been shown that the loss of the area will not prevent a safe shutdown of the station. For these reasons, the 7 minute outage is determined to be acceptable for this area's fire detection and suppression systems.

The manual switchover to emergency power for the fire alarm system is unaccept able. Since the plant safety systems have to be manually switched to emergency power it is assumed that the diesel generators are not of §ufficient size to pick up the entire electrical load of the plant.

If the diesels had this capability automatic transfer switches would be provided for the safety systems. Since the fire alarm systems are not necessary for a plant operations, the system may not be manually transferred to emergency power in a situation of critical power requirements.

The fire alarm system protects highly critical areas of the plant required for safe shutdown. A time delay of from 2 to 7 minutes does not comply with our interpretation of the rule 10CFR Part 50 - II F "Automatic Fire Detection where "prompt modification and alarm" is required. We recommend that automatic power back-up be supplied for the fire alarm system; this can be a battery or diesel generator system where no manual transfer is required.

This recommendation is applicable to the items in 3.1.1 of the SER, but it is not by itself an asterisked item of the SER.

Item 7 Provide the basis for using a temperature alarm setpoint of 2800F for the line type heat detection system of the Cable Tray Fire Detection System in the Lube Oil Reservoir and Conditioner Area.

Response

The cable trays in this area contain power and control cables with ratings up to 266 F. Hot spots and cab e fires are only expected to occur at or near the rated value. A setpoint of 280 F provides sufficient margin to minimize the likelihood of spurious action yet is adequate to protect the cables from a fire both in ternal and external to the cable trays.

The 2800F temperature alarm setpoint for the Cable Tray Fire Detection System in the Lube Oil Reservoir and Conditioner Area is acceptable but we recommend that final acceptance of 3.1.5(B) be withheld until the recommendations-intBNL letter dated April 16, 1980 are complied with.

Item 10 Provide design drawings and detailed description of the Reactor Coolant Pump Lube Oil Drain Pans and Spray Shields. Will the system completely enclose all-

pressurized portions of lube oil piping associated with the RCP's? Where will the oil be drained to? Can the drains handle the entire inventory of 1 RCP?

Response

Enclosed drawings (5154154, 5154155) are provided for your review. The pressur ized portions of the lube oil piping will be completely enclosed. Thessphere sump pump will convey spilled oil to the decontaminationddrain tank (D-26).

This tank has a capacity of 350 cubic feet (approximately 2700 gals.).

Since each reactor coolant pump has lubricating oil inventory of less than 250 gallons, the radioactive waste system can easily accommodate a spill from any one pump.

The above referenced drawings were reviewed and found acceptable except for the collection point. The licensee wants to use a containment sump instead of a vented closed container. We recommend that the licensee modify their design to include the vented closed container. Based upon-the above review and recommenda tion, the first part of 3.1.15h Oil Collection System is acceptable.