ML20127H010
| ML20127H010 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 01/13/1993 |
| From: | William Cahill, Woodlan D TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TXX-93021, NUDOCS 9301220145 | |
| Download: ML20127H010 (2) | |
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Log # TXX-93021 File i 10010 Ref # 10CFR50.34(b) 7UELECTRIC January 13, 1993
% Hlum J. Cubill, Jr.
tav.up 1 a e he d.k ou U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NOS. 50-445 AND 50-446 REQUEST FOR ADDITIONAI. INFORMATION ON RXE-89-002 VIPRE-01 CORE THERMAL-HYDRAULIC ANALYSIS METH00S REF:
TU Electric Letter TXX-89441, dated June 30, 1989, from Mr. William J. Cahill, Jr. to the USNRC Gentlemen:
This letter provides additional clarification regarding the subject topical report transmitted by the referenced letter.
The TV Electric DNB analysis methodology incorporates a retained, or
" generic", ONBR margin that can be used to offset penalties such as rod bow.
The available margin is the difference between the design DNBR acceptance limit and the NRC approved 95/95 DNBR correlation limit. An example is given below:
TUE-1 95/95 correlation limit 1.16 Retained margin
+A Design limit 1.16 + A In this example, the retained DNBR margin (A) is available to offset rod bow and other penalties. The retained margin (and the design limit) will be maintained such that there is always sufficient margin available for DNB penalties.
DNB penalties are calculated and tracked within TU calculations, using approved DNB analysis methodology as described in RXE-89-002.
With respect to the Core Operating Limits Report, Technical Specification 6.9.1.6 will be revised to reference the approved VIPRE modeling methodology as described in Topical Report RXE-89-002.
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l TXX-93021 Page 2 of 2 Should clarification or additional information be required, please contact Mr. Bob Dacko at (214) 612-8228.
Sincerely, William J. Cahill, Jr.
By:
6 O. R. Woodlan Docket Licensing Manager BSO/grp i
c-Mr. J. L. Milhoan, Region IV Resident inspectors, CPSES (2)