ML19317G983
| ML19317G983 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/21/1978 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8004020642 | |
| Download: ML19317G983 (5) | |
Text
- 4o REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
DISTRIBUTION FOR INCOMING MATERIAL 50-312 REC: REID R W ORG: MATTIMOE J J DOCDATE: 02/21/78 NRC SACRAMENTO MUN UTILITY DISTRIC DATE RCVD: 02/27/78 DOCTYPE: LETTER NOTARIZED: NO COPIES RECEIVED
SUBJECT:
LTR 1 ENCL 40 FORWARDING
SUMMARY
OF ANALYSIS IN RESPONSE TO NRC REQUEST NO 5.
POSITION 3, RE ANALYSIS OF A MODERATE ENERGY LINE BREAK IN RESPECT TO FIRE HAZARD ANALYSIS.
PLANT NAME: RANCHO SECO (SMUD)
REVIEWER INITIAL:
XJM DISTRIBUTOR INITI AL:
- DISTRIBUTION OF THIS MATERIAL IS AS FOLLOWS ******************
FIRE PROTECTION INFORMATION (AFTER ISSUANCE OF OL).
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SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S Street, Box 15830, Sacramento, Califomia 95813; (916) 452-3211 February 21, 1978
,9mt Director of Nuclear Reactor Regulation 8
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( Q pg r,[,,' ~/ ' ' s Attention: Mr. Robert W. Reid, Chief Operating Reactors, Branch 4 U. S. Nuclear Regulatory Conmission N 7,'
Washington, D. C.
20555
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i A.f Docket No. 50-312 Rancho Seco Nuclear Generating Station, Unit No. 1
Dear Mr. Reid:
Our letter of February 1,1978 transmitted the District's responses to NRC requests for additional information regarding the Rancho Seco Fire Hazard Analysis.
The District's response to NRC Request No. 5, Position No. 3, stated that an analysis of a moderate energy line break would be sub-mitted by March 1,1978.
Enclosed with this letter are forty (40) copies of a summary of our analysis.
Sincerely yours,
. 7M J. J. Mattimoe Assistant General Manager and Chief Engineer Enclosures O
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- SACRAMENTO MUNICIPAL UTILITY DISTRICT RANCHO SECO NUCLEAR GENERATING STATION, UNIT N0. - l RESPONSE TO REQUEST NO. 5, POSITION NO. 3 0F
. NUCLEAR REGULATORY COMMISSION REQUEST FOR liiF0RMATION REGARDING ENCLOSURE 1 0F NRC TO SMUD LETTER DATED JANUARY 18, 1978 TITLED REQUEST FOR ADDITIONAL INFORMATION 4
February 21, 1978
NRC REQUEST FOR INFORMATION NRC REQUEST N0. 5:
The response to PF-ll in your letter dated August 1,1977, is unacceptable because the concern is not only for routine hydrant maintenance, but also for situations where hydrants are damaged by vehicles or mechanical failure.
Certain of these failures would cause the loss of all water suppression capability in the turbine building or auxiliary building.
It is our position that:
(1) the valves in the lines feeding these buildings from the main Toop be locked open or control room electrical supervision be provided, (2) curb valves be installed on the hydrants whose failure could cause the loss of suppression water to the auxiliary building or the turbine building, and (3) a moderate energy line break analysis be done for fire protection piping for safety related areas where the primary and backup suppression is fed from a common pipe to assure that sufficient water can be supplied to the water suppression systems under such conditions.
APCS Branch Technical Position 3-1 should be used to determine the crack size to be assumed.
RESPONSE TO POSITION N0. 3 0F NRC REQUEST N0. 5:
The moderate energy line break analysis performed by the District evaluated the impact of the postulated break on the performance of the two basic types of water protection in safety related areas.
1.
An analysis of the effects of a pipe break aijacent to the most remote fire hose station protecting safety related equipment showed that the performance of the hose stream was not impaired.
The analysis considered operation of the electric driven fire pump only since it produces slightly less head than the redundant diesel driven fire pump.
The analysis considered all piping system friction losses from the pump to the hose nozzle for combined flow, as applicable, of the hose nozzle and the postulated crack.
With the crack in the most adverse location, the hose stream exceeded 60 gpm with a pressure at the base of the nozzle in excess of 100 psi which is considered very acceptable.
2.
An analysis of the effects of the postulated break on the wet pipe sprinkler systems showed that the perfonnance of the system was :ot impaired.
The analysis considered operation of the electric driven fire pump only for the reasons outlined above.
The analysis considered a crack occurring in the 8" main,just upstream of the laterals to the various Auxiliary Building systems.
,. The analysis considered ' operation of all sprinkler heads (35 total) in the grade level electrical penetration area of Fire Area 34 (the largest single hazard).
With the postulated crack present, flow to the sprinklers was '10ll gpm providing a design density of 0.33 gpm per square foot for the 3070 square foot area covered.
This flow rate significantly exceeds the requirements for all areas of the Auxiliary Building, even ordinary hazard, Group 3 occupancies.
(Reference NFPA Fire Protection Handbdok,14th Edition, Tables14-14B, Pages 14-46.) Therefore, the presence of a moderate energy crack does not have a significant adverse effect on this and other safety related areas.
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