ML19323B726

Requests Util Confirmation of Conclusion of Encl GE Study, DC Power Supply Failure. List of Equipment Available for Large & Small Recirculation Loop Discharge & Suction Breaks Should Be Included in Response

ML19323B726
Person / Time
Site:	Browns Ferry
Issue date:	04/25/1980
From:	Ippolito T Office of Nuclear Reactor Regulation
To:	Parris H TENNESSEE VALLEY AUTHORITY
References
NUDOCS 8005140141
Download: ML19323B726 (3)

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APRIL 2 5 1980 Docket Mos. 50-259 50-260 and 50-296 Mr. Hugh G. Parris Manager of Power Tennessee Valley Authority 500A Chestnut Street Tower II Chattanooga, Tennessee 37401 i

Dear Mr. Parris:

SUSJECT: EFFECT OF A DC POWER SUPPLY FAILURE ON ECCS PERFORMANCE It has generally been recognized that the loss of a direct current (DC) power supply could disable several emergency core cooling system couponents and thereby could result in a limiting single failure condition for some breaks. The enclosed letter report was submitted to the NRC staff by the General Electric Conpany to provide a definitive, generic, reference analysis of the effects of DC power supply failures on ECCS confonnance t

calculations. The NRC staff is reviewing the analysis which conpares the peak cladding temperatures associated with various postulated DC power supply failure (ECCS egipment availability) cases to the peak cladding tenveratures for a HPCI (small break) failure and LPCI infection valve (large break) failure cases. Since the study was based on plant design infctmation which may have been incomplete or out-of-date, some uncer-tainty exists whether the worse ECCS system availability combinations have been identified for your operating BWRs. Accordingly, in order that we may have an adequate level of assurance that the systems con-binations assumed in the generic analysis are conservative for Browns Ferry Units Nos.1, 2 amd 3, we request that you confinn the conclusion of the reference study regarding the minimum ECCS equipment _ availability with a DC power supply failure. Include in your response a list of the ECCS equipment that would be available for large and small (1) recircula-tion loop discharge breaks, and (2) recirculation loop suction breaks.

The listing of equipment available should take into account not only DC power supply failure, but also loss of equipment due to water spillage.

Please provide a schedule for your response within 30 days of the receipt of this letter.

2-APRIL 2 5 1980 Mr. Hugh G. Parris This request for generic infersation was approv'ed by GA0 under clearance number B-180225(579018); this clearance expires October 31, 1980.

Sincerely,

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/7 o, Chief Operating Reactors Branch #3 Division of Operating Reactors

Enclosure:

General Electric Cocpany letter (R. E. Engel) to USNRC (P. S.

Check), "DC Power Source Failure for BWR/3 and 4 " dated Noyesber 1, 1978.

cc w/ enclosure:

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Mr. Hugh G. Parris APRIL 2 5 1980 cc:

H. S. Sanger, Jr., Esquire General Counsel Tennessee Valley Authority 400 Commerce Avenue E 118 33 C Xnoxville, Tennessee 37902 Mr. Ron Rogers.

Tennessee Valley Authority 400 Chestnut Street, Tower II Chattanooga, Tennessee 37401 Mr. H. N. Culver 249A HSD 400 Coranerce Avenue Tennessee Valley Authority Knoxville, Tennessee 37902 Robert F. Sullivan U. S. Nuclear Regulatory Cocnission P. O. Box 1863 Decatur Alabama 35602 Athens Fublic Library South and Forrest Athens, Alaba:na 35611 l

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GENERAL 4 ELECTRIC wuctuan susaav P FI O J E C T S DIVISIO N GENERAL ELECTRIC COMPANY,175 CURTNER AVE., SAN JOSE, CALIFORNIA 95125 MC 682, (408) 925-1153

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November 1, 1978 REE- 054 ' 8 7

MFN -410-78 U.S. Nuclear Regulatory Commission Division of Operating Reactors Washington, D.C. 20555 Attention:

P.S. Check, Chief Reactor Safety Branch Operational Technology

SUBJECT:

DC Power Source Failure For BWR/3 and 4 A recent concern expressed by members of your staff is the effect of a direct current (DC) power source failure on the currently approved 10CFR50.46 conformance calculations for operating BWR/3's and 4's.

The General Electric Company has conducted a study of this concern and has documented the results in Attachment 1 to this letter. An additional concern expressed was the lack of a peak cladding temperature (PCT) versus break area curve in the small break region which could be applied to operating BWR/3's and 4's.

This concern is also covered in Attachment 1.

The study was performed with the 1977 approved model and input changes using bounding assumptions to provide a generic result applicable to all operating BWR/3's and 4's.

The results of the study shor that there is an increase in PCT for small breaks; however, the FCT remains less than 1950 F.

For large breaks, the PCT was not affected. Also, the ma.ximum average planar linear heat generation rate (MAPLHGR) is not affected for any plant.

If you have any questions or comments, please i:ontact R. T. Hill of my staf f t

. b'?b on (408) 925-3255.

Sincerely, L-9 R. E. Engel, Manager p

Operating Licenses I

1. h Safety and Licensing Operation l

Attachment cc:

F. D. Coffman R. H. W. Woods

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1 ATTACHMENT 1 DC P0k'ER SOURCE FAILURE FOR Bk'R 3 AND 4 i

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