ML19317G813
| ML19317G813 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/11/1977 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| 1568, NUDOCS 8004010641 | |
| Download: ML19317G813 (3) | |
Text
I NRC PenM 195
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u.s. NUCLEAR REGULATORY ' MMISSION DOCKET NUM SE R vn m
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NRC,DISfTRIBUTION FOR PART 50 DOCKET MATERIAL FROM:
DATE OF DocuMEN7 TO:
Mr R W Reid Sacramento Municipal Ut. Disi 2-11-77
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Sacramento, C-h.f J J MattimOe DATE RECFtVED 2-14-77
@LE'TTER ONOTORIZED P R OP INPUT FORM NUMBER OF COPIES RECEIVED
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One Signed CCOPY DEfCRIPTION ENCLOSU RE
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Ltr re Our 1-7-77 ltr..... furnishing info cone
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carning list Of applicable thermal credits for y
future re ference.........
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SAFETY FOR ACTION /INFORMATION pwvTun 2-14-77 ehf ASSIGNED AD:
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BRANCH CHIEF.
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PROJECT MANAGERr Mrs a n t 4 PROJECT MANAGER:
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SYSTEMS SAFETY PLANT SYSTEMS SITE SAFETY &
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SCHROEDER BENAROYA DENTON & MUT.T FR i
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MIPC MACARRY ETREWOOD ERNST CASE KNICHT BALLARD HANAUER SIHWEIL OPERATING REACTORS SPANGLER HARLESS PAWLICKI STELLO I,
SITE TECH.
1 PROJECT MANAGEMENT REACTOR SAFETY OPERATING TECH.
GAMMILL BOYD ROSS
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EISENHITF STEPP P., COLLINS NOVAK
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SHAO HULMAN HOUSTON ROSZTOCZY
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BAER PETERSON CHECK
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BUTLER SITE ANALYSIS I
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gSMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 s street. Box 15830, sacramento, California 95813; (916) 452-3211 February 11, 1977
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Director of Nuclear Reactor Regulation
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El/gy Attention: Mr. Robert W. Reid, Chief i
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Operating Reactors, Branch 4 V. S. Nuclear Regulatory Comission
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Docket No. 50-312 Rancho Seco Nuclear Generating Station, Unit No. 1
Dear Mr. Reid:
Please refer to your letter of January 7,1977 requesting a list of applicable thermal margin credits for future reference on the Rancho Seco docket.
The evaluation of margins available to offset a potential NBR penalty resulting from fuel rod bow has resulted in the identi-
.fcation of-the following offsets for Rancho Seco:
1.
Flow Area Reduction Factor:
This factor, used in subchannel analyses, accounts for manufacturing variations in fuel rod pitch.
This factor has been shown to be equivalent to a 1% DNBR penalty.
2.
Densification Power Spike Penalty:
This penalty, 3.3% DNBR for Cycle 1 of Rancho Seco, has been shown to be no longer necessary.
3.
Reactor Coolant System Flow Rate in Excess of Design Flow Rate:
Based upon measurements taken prior to, and during, first cycle operation of Rancho Seco, the RCS flow rate is 108.6% of the design flow rate, with a maximum uncertainty of 3.5%.
(This increase in flow had con-servatively been estimated, W y,
ea alent to 4.0%
DNBR.)
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m Rr. Robert W. Reid February 11,1977 The initial rod bow penalty evaluation for Rancho faco was based upon the NRC bow prediction for B&W fuel (oC = 9 + 0.2 Ju~) and a linear interpolation of the Westinghouse data which indicates a.34%
penalty for full closure (P = 34 h).
Based upon a rod-to-rod gap (Co) of 138 mils, this results in the following DNBR penalties:
Previously Identified Burnup DNBR Penalty Offsets Net Penalty 15,000 8.2%
8.2%
0%
24,000 9.8%
8.2%
1.6%
33,000 11.2%
8.2%
3.0%
The Babcock & Wilcox Company is performing a thermal hydraulic analysis for licensing of Fuel Cycle 2.
This analysis should provide an acceptable method of accomodating the DNBR reductions for increased fuel burnup and will be included in our submittal for licensing of Fuel Cycle 2.
Sincerely yours,
. J. Mattimoe Assistant General Manager and Chief Engineer
.