ML19317G980
| ML19317G980 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 08/01/1977 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8004020640 | |
| Download: ML19317G980 (10) | |
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U.S. NUCLEAQ C EIULATCnv cob
.SION DOCKET NUMBE R
.n NRC DISTRIBUTION roR PART 50 DOCKET MATERI AL Tc.
FROM:
DATE OF DOCUMENT Robert W. Reid Sacramento Municipal Utility Dist.
8/1/77 Sacramento, CA oATE RECEivEo J. J. Mattimoe 8/4/77 JirgETTE R ONOTORIZED PROP INPUT PORM NUMBER OF COPIES RECEIVED dCRIGINAL (EDNCLAS$1 PIE D aCoPv i 6/ A AJeD DESCRIPTION ENCLOSU RE Enclosed additional info requested in ltr or 4/15/77 concerning fire pro tection.
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DISTRIBUIION OF FIRE PROTECTION INFO PER S.SHEPPARD 9-22-76 FOR OPERATING REACTORS e
7 Rancho Seco Nuclear Generating Station Unit No. 1 RBT 8/5/77 san.IY FOR ACTION /INFORMATION BRANCH CHIEF:( 3 )
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esuuo SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S Street, Box 15830, sacramento, California 95813; (916) 452-3211 u-August 1,1977 y
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Director of Nuclear Reactor Regulation Attention: Mr. Robert W. Reid, Chief EY
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Operating Reactors, Branch 4 O
C4 1977, 3 U. S. Nuclear Regulatory Commission
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Rancho Seco Nuclear Generating 5
Station, Unit No.1
Dear.Mr. Reid:
Please refer to your letter of April 15, 1977 wherein you requested that the District furnish the NRC with additional information regarding fire protection for the Rancho Seco Nuclear Generating Station, Unit No. 1.
Enclosed with this letter are 40 copies of our response to your request for information.
Sincerely yours,
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J. J. Mattimoe Assistant General Manager and Chief Engineer Enclosures
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i SACRAMENTO MUNICIPAL UTILITY DISTRICT RANCHO SECO NUCLEAR GENERATING STATION, UNIT NO. 1 RESPONSE TO:
NUCLEAR REGULATORY COMMISSION REQUEST FOR INFORMATION REGARDING ENCLOSURE 2 0F NRC TO SMUD LETTER DATED APRIL 15, 1977 TITLED STATEMENTS OF STAFF POSITION SACRAMENTO MUNICIPAL UTILITY DISTRICT RANCHO SEC0 GENERATING STATION DOCKET NO. 50-312 s
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NRC REQUEST FOR INFORMATION NRC ITEM PF.1 -' EMERGENCY BREATHING APPARATUS (RANCHO SECO)
NRC Staff Position:
Provide sufficient air masks for the operating crew and fire brigade with the two spare bottles for each required mask, and an emergency air supply of at least six hours.
This capability may consist of either an air compressor, air tanks of sufficient capacity or a sufficient supply.of charged air bottles. The charging equipment should have a charging rate that is adequate to assure a continuous supply of charged bottles.
Response
A fire brigade of three members shall be maintained on site at all times.
In addition, during normal working hours, a backup fire brigade of eight (8) trained personnel will be available.
The air masks and s re bottles which the District currently has are s
adequate for this crew.
For a backup air supply, the District will purchase a compressor which will have a capacity of 5 cfm and will be capable of recharging a 30-minute rated air tank every eight (8) minu tes.
Please refer to the District's Fire Hazard Analysis Report submitted under separate letter dated August 1,1977 for a discussion regarding implemer.tation of plant modifications for fire protection.
NRC ITEM PF.2 - EMERGENCY VENTILATION EQUIPMENT DUCTWORK (RANCHO SECO)
NRC Staff Position:
The ductwork stored in the Battery Charger and Panel Distribution Room should be moved to another area which is readily accessible.
Response
The District has no objection to relocating the ductwork as requested.
An investigation will be conducted to locate an area where there is a relatively low fire risk and easier accessibility to the ductwork.
Please refer to the District's Fire Hazard Analysis Report submitted under separate letter dated August 1,1977 for a discussion regarding implementation of plant modifications for fire protection.
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,' NRC ITEM PF.3 - ESTABLI HMENT OF FIRE AREAS (RANCHO SECO)
NRC Staff Position:
Separate fire areas enclosed by floors, walls, and ceilings having a minimum three-hour fire rating should be established. These fire areas should be selected as much as practicable, such that safety-related equipment is isolated from significant fire hazards and redundant safety-related equipment is in separate fire areas.
Penetrations through the fire barriers should be sealed to prevent fire spread through a penetration.
Response
Please refer to the District's Fire Hazard Analysis Report dated August 1,1977 for identification of the fire areas.
The District proposes to upgrade, install and/or test the cable tray penetration fire stops in walls separating safety related equipment to provide the resistance rating required by the fire loading shown in the Fire Hazard Analysis.
However, this work cannot be accomplished in the one year requested.
It will be.necessary to install a numbe. of fire stops in the Reactor Building and we propose to do this work during the second refueling outage currently scheduled for the fall of 19/8. Attempting to do the work sooner would require an extensive unit outage.
The modifications required to upgrade the plant security systems (and fire door supervision) will require installing new raceways in the majority of the Auxiliary Building cable tray penetrations.
It is the District's opinion that delaying upgrading the Auxiliary Building cable tray fire stops until completion of the security system modifi-cations will result in improved fire stop integrity since breaching the upgraded stops will be avoided. Therefore, the District does not plan to start this work until the security systems are complete, which is currently scheduled for August 1978.
NRC ITEM PF.4 - LOCATION AND FILLING OF FUEL OIL STORAGE TANK (RANCHO SECO)
NRC Staff Position:
To prevent safety-related equipment within the plant yard from being disabled by a possible fire at the diesel generator storage tank location during filling operations, one of the following should be accomplished:
(a) Move the fill location so that a tank truck fire cannot affect safety-related equipment, or (b) Provide fixed protection designed to prevent the safety-related equipment from being damaged by a fuel oil fire.
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. Response:
The District proposes to relocate the fill and vent connections for Diesel Fuel Oil Storage Tank T-887B to plant Coordinates N62 + 80, E33 + 95.
Please refer to the District's Fire Hazard Analysis Report submitted under separate letter dated August 1,1977 for a discussion regarding implementation of plant modifications for fire protection.
NRC ITEM PF.S - CABLES IN CONCEALED C G LING SPACE-COMPUTER ROOM (RANCHO SECO)
_NRC Staff Position:
A fixed fire suppression system should be provided in the concealed ceiling space of the computer room.
Response
The NRC staff's concern about accessibility of cables above the computer room ceiling is well founded. To rectify this problem, the District proposes to remove the suspended ceiling, thus, making the cable fully accessible for manual fire suppression techniques.
Please refer to the District's Fire Hazard Analysis Report submitted under separate letter dated August 1,1977 for a discussion regarding implementation of plant modifications for fire protection.
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- CABLES IN CONCEALED CEILING SPACE-AUXILIARY BUILDING CORRIDORS NRC Staff Position:
Provide a fire suppression system that is adequate to effectively control a fire in this area and to prevent it from involving more than one safety division, such as an automatic fixed water spray.
Additionally, provide a fire barrier or fire stop between the two divisions of cabling in the concealed corridor ceiling space.
Response
The District does not agree with the NRC staff regarding the adequacy of the sprinklers in the corridors.
Tests conducted on September 23, and 24, 1975 in Rautaruukki Oy's Factory, Raahe, Finland, were intended to answer the questions:
1.
"Is a standard sprinkler installation with 57 C sprinklers able to extinguish a fire in a cable duct where layers of cables on several cable trays on top of each other prevent the water distribution from a sprinkler direct to the burning cables?"
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"How far will the fire spread before the sprinkler installation gets the situation under control?"
The conclusions state in part:
1.
"A" standard sprinkler installation is. capable of extinguishing a fire in cables in a cable room or a cable-duct, even if there are several tra: '. on top of-each other and the cables form thick, dense layers on :ne trays. _ No cable layer can be watertight; water will always flow through the cable layers to the cables on the lower trays. Additionally, Test No. III showed that the fire will be put out also below a steel plate.
Without carrying out additional
' tests it cannot be predicted how cables with polyethylene and rubber insulation would.have performed in Test No. III.
In Test No. I and II also such cables would have been extinguished with all probability. _ No statements regarding the fire behavior and extinguishing of oil filled cables can be made on behalf of this test."
2.
"The fire in a sprinkler protected cable duct will not spread downwards nor to the cable trays on the opposite side of the gang-way."
These tests were conducted in a duct whose configuration was almost identical to the Rantno Seco corridors-(6.56 feet wide by 6.56 feet-high duct versus 8 feet wide by 10 feet high corridor).
The duct had trays stacked six deep up both sides which were densely filled with highly flammable (PVC) cable.
Sprinklers were installed at the top center of the duct on 13' centers.
The Rancho Seco sprinklers are on center distances ranging from 8'to 12'.
These tests clearly show that the sprinklers installed at Rancho Seco are adequate and that fixed water spray providing direct impingement
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of water on all cables is not necessary for effective fire suppression.
Due to its length, the report is not being included in this response; however, copies are available in the District's Office for review by the NRC staff if they desire.
Please refer to the District's Fire Hazard Analysis Report submitted under separate letter dated August.1,1977 for a discussion regarding separation in Fire Areas 29 and 36.
i NRC ITEM PF.7 - SUPERVISION OF CO2 SYSTEM MAIN SHUT 0FF VALVE (RANCHO SECO) i I
NRC Staff Position:
The main _ shutoff valve on the CO2 system tank should be electrically.
j supervised or locked open with the key under management control.
Response
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The District proposes to modify the fire protection system monitoring provisions such that the CO2 system main shutoff valve will be electri-cally supervised and alarmed in the control room both visually and -
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Please refer to the District's Fire Hazard Analysis Report submitted under separate letter dated August 1,1977 for a discussion regarding implementation of plant modifications for fire protection.
NRC ITEM PF.8 - LOCKING OR ALARMING OF DOCRS THROUGH FIRE BARRIERS (RANCHO SECO)
NRC Staff Position:
All doors in the fire barriers protecti a :afety related areas should be alarmed with a time delay so that if :.2 door is left open, the control room is notified.
Response
The District proposes to alarm all doors in fire barriers of safety related areas as defined in the Fire Hazard Analysis Report dated August 1,1977.
The alarm signal will be annunciated on the same console as is being installed for monitoring doors essential for security.
This console will be manned by the security personnel and they will have total responsibility for door control.
This work will be completed in conjunction with the modifications required for the upgraded security systems which is currently scheduled for August 1978.
NRC ITEM PF.9 - CABLE PENETRATION FIRE STOP TEST (RANCHO SECO)
NRC Staff Position:
The fire stops should be tested to demonstrate a fire rating equivalent to the rating required for the fire barrier in which the penetration is used.
The tests should be performed or witnessed by a representative of a qualifitd independent testing laboratory.
The tests should be performed in accordance with ASTM E-119, with the following exceptions:
(1) The cables used in the test should include the cable insulation materials used in the facility.
(2) The test sample should be representative of the worst case con-figuration of cable loading, cable tray arrangement and anchoring, and penetration fire stop size and design.
The test sample should also be representative of the cable size in the facility.
Testing of the penetration fire stop in the floor configuration will qualify the fire stop for use in the wall configuration also.
(3) Cable penetrating the fire stop should extend at least three feet on the unexposed side and at least one foot on the exposed s1}de.
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- (4) The fire stop should be tested in both directions unless the fire stop is symmetrical.
(5) The fire stop should be tested with a pressure differential across it that is equivalent to the maximum pressure differential a fire stop in the plant is expected to experience.
(6) Temperature levels of the cable insulation, cable conductor, cable tray or conduit, and fire stop material should be recorded for the unexposed side of the fire stop.
(7) Acceptance criteria - the test is successful if:
a.
The cable penetration fire stop has withstood the fire endurance test without passage of flame or ignition of cables on the unexposed side for a period equal to the required fire rating, and b.
The temperature levels recorded for the unexposed side are analyzed and demonstrate that the maximum temperatures are sufficiently below the cable insulation ignition temperature, and c.
The fire stop remains intact and does not allow projection of water beyond the unexposed surface during the hose stream test.
If tests which have already been performed meet the above position, the licensee should provide the results of the tests to show that the above position is met.
Response
The District is currently implementing a program to test the fire stop designs used in the Rancho Seco plant.
Resulting test data will be forwarded to the NRC as soon as it is available.
NRC ITEM PF.10 - ELECTRICAL PENETRATION AREA SPRINKLER SYSTEMS (RANCHO SECO)
NRC Staff Position:
The automatic wet-pipe sprinkler system in the penetration areas should be modified to provide a directed water spray on the cabling.
Response
The test discussed under Item PF.6 clearly shows that standard sprinklers are effective in suppressing fires in cable trays stacked at least six rows deep, even when they are densely filled and with solid steel partitions installed between them.
Based on this test data, the District cannot agree with the NRC staff's concern.
We do not propose to take any action on this item.
. NRC ITEM PF.ll - CURB VALVES ON YARD-LOOP HYDRANTS (RANCHO SECO)
NRC Staff Position:
Curb valves should be provided for those yard loop hydrants which cannot be isolated without also causing loss of suppression capability protecting safety-related equipment.
Response
There is only one hydrant on the yard main system that is contiguors to laterals supplying suppression systems in safety-related areas.
Our insurer, NELPIA, requires that we cycle all fire system vahes closed and open once each year to verify operability.
Therefore, any curb valve installed would see approximately the same duty cycle as the hydrant it isolates.
We would anticipate as much maintenance on the curb valve as would be required for the hydrant. Additionally, protection would have to be interrupted for a significant period of time to install a curb valve.
The District does not feel the possible benefit of having a curb valve justifies the outage required to install it.
Therefore, no action is planned.
NRC ITEM PF.12 - FIRE DETECTORS IN CONTROL ROOM CABINETS (RANCHO SECO)
NRC Staff Position:
Smoke or heat detectors should be provided in each safety-related cabinet and console in the control room / computer room area.
Response
The District proposes to install smoke or heat detectors in control or computer room cabinets which contain wiring or devices required for shutdown or cooldown of the reactor.
Please refer to the Fire Hazard Analysis Report, Response to Question No. 26, for a discussion of the effects of postulated fires in the control / computer room cabinets of concern.
Also, please refer to the District's Fire Hazard Analysis Report submitted under separate letter dated August 1,1977 for a discussion regarding implementation of plant modifications for fire protection.
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