ML18142A836
| ML18142A836 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 02/11/1977 |
| From: | White L Rochester Gas & Electric Corp |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| Download: ML18142A836 (5) | |
Text
U.se NUCLEAR REGULATORY C ISSION NRC>ORA 1 5 (2 78)
CIRC DISTRIBUTION FoR PART 50 DOCKET MATERIAL DOCKET NUMBER 50-244 FILE NUMBER TO:
-Mr. A. Schwencer FROM:
Rochester Gas
& Electric Co.
Rochester, New York L. D. White Jr.
DATE OF DOCUMENT
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2/11/77
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DATE RECEIVED 2/16/77
/(LETTER ORIGINAL
~QCOPY DESCRIPTION
'0 NOTOR I2 E D
-ISUNCLASSIFIED PROP INPUT FORM ENCLOSURE NUMBER OF COPIES RECEIVED
. One sz.gned Ltr. furnishing response to our 1/12/77 request for information on fuel rod bowing'nd on DNBR margins presently available.
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PLANT NAME R. E. Ginna No.
1 SAFETY ASSXGNED AD!
FOR ACTION/INFORMATION Schwencer 2
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ROCHESTER GAS AND ELECTRIC CORPORATION o
89 EAST AVENUE, ROCHESTER, N.Y. 14649 LEON D. WHITE, JR.
VICE RRESIOENT TELEPHONE AREA cooE 7ld 546.2700 February ll, 1977 Director of Nuclea'r Reactor Regulation Attention:
Mr. A. Schw'en'cer, Chief Opexating Rea'ctors Branch 0'!
U.S. Nuclea'r Regulatory Commission Washington, D.C.
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Dear Mr. Schwencer:
>r,O 1I This letter is in res'ponse
'to your reques f
. ~2, 1977 for information on fuel'od bowing and on D h rh ns presently available.'e have 'reviewed our fuel design in de il with our
- supplier, Westingho'use 'Elec'tric Corporation, and have obtained the DNBR margins which 'are pres'ently available.
Protection against reaching DNB ratios less than 1.30 is provided in two plant protec'tion setpoints, the 'underfrequency trip set-point. and the'vertemperature aT setpoint.
The underfrequency trip provides'rotection for the loss-of-flow design basis accident while the ovex'temperature 5T trip provides protection for other potentially limiting DNB rel'ated transients.
Thepresent Technical Specification limit for the underfrequency trip setpoint is 57.5 Hz, however a
change 'in the Tec'hn'ic'al Spec'ification limit to 55 Hz was requested by application dated November',
1976.
The analysis supporting this application showed a minimum DNBR during the loss of flow accident of 1.615 for a trip setpoint of 55 Hz and a frequency decay rate of 5 Hz/sec
, for a margin of 24.2% to a DNBR of 1.30.
In addition, mar-gins 'are available 'in the'NBR analysis for the thermal diffusion coefficient'f 3'.'0% and for the 'pitch 'reduction of 3.3%.
- Thus, a total margin of 30.5% is available 'for the'oss of flow design basis accident.
The analysis supporting sel'ection of the Technical Specification limit on the oVertemperature
'nT trip setpoint was originally performed for Cycle '3 and was submitted to the'RC on February 16, 1973.
In this analysis a 9.9%
DNBR penalty for densification heat flux spike and a
10.0%
DNBR penalty for fuel rod flattening wer'e incorporated.
As neither'f the'se 'pen'alties're.
required now, they provide for a margin of 19.9%.
In addition, thether'mal diffusion coefficient and pitch reduction margins are 'availabl'e, yiel'ding a total margin of 26.2%.
Analysis for Cycl'e 5, submitted to the NRC on March 26, 1975, resulted in a slight increa'se in theovextemperature 6T trip setpoint, thereby using 4.0%, of the DNBR margin.
Inasmuch as the overtemperature bT has not been changed since 'the 'Cycle 5 analysis, a
DNBR margin of 22.2%
is now available.
ROCHESTER GAS AND ELECTR ORP.
February ll, 1977 To Mr. A. Schwencer, Chief Operating Reactors Branch 41 SHEET NO.
2 In addition to reviewing the DNBR margins available, we have reviewed fuel inspection data.
As discussed in our letter of August 18,
- 1976, no fuel rod bowing has be'e'n seen in television examination of fuel assemblies with assembly aver'age burnups in excess of 2S,000 MWD/MTU.
Any assessment of potential DNBR penalties should, in our opinion, be consistent with thes'e 'actual measured data.
In summary, DNBR margins of at least 22.2% are available.
In addition, no fuel rod bowing has bee'n observed in Ginna 9 grid, stainless steel guide tube, 14 x 14 fuel.
Very truly yours, L.D. Whi e, Jr.
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