ML13330A454
| ML13330A454 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 11/21/1984 |
| From: | Medford M SOUTHERN CALIFORNIA EDISON CO. |
| To: | Zwolinski J Office of Nuclear Reactor Regulation |
| References | |
| TAC-56067, NUDOCS 8411260214 | |
| Download: ML13330A454 (3) | |
Text
Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD, CALIFORNIA 91770 M.O.MEDFORD TELEPHONE MANAGER, NUCLEAR LICENSING November 21, 1984 (818) 5721749 Director, Office of Nuclear Reactor Regulation Attention:
Mr. J. A. Zwolinski, Chief Operating Reactors Branch No. 5 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Gentlemen:
Subject:
Docket No. 50-206 Increased Power Peakings San Onofre Nuclear Generating Station Unit 1
Reference:
Letter dated October 17, 1984, M. 0. Medford, SCE, to W. A. Paulson, NRC, Concerning Increased Power Peakings The reference letter provided a proposed change to the basis for Technical Specification 3.5.2 "Control Group Insertion Limits".
This change was proposed in connection with the safety evaluation for the Cycle 8 restart of San Onofre Unit 1. A recent three-way telephone conversation among parties from SCE, Westinghouse Nuclear Technology Division and NRC staff identified the need for additional information relating to the safety evaluation submitted with the proposed basis change. Specifically the NRC staff reviewer asked why the justification for the continued applicability of the small break LOCA analysis Is brief and does not contain numerical detail similar to the large break LOCA justification. In response, Westinghouse provided a verbal explanation which is reiterated below.
The large break LOCA analysis used FAH as an explicit input with other parameters to determine the magnitude of the chopped cosine power shape for the hot rod axial power distribution. In the small break LOCA analysis, however, FAH is not an explicit input. A conservative hot rod axial power distribution was input to the code directly. The actual power shape assumed is.provided in the attached figure. The peak linear power assumed in the small break analysis (14.2 Kw) is conservative with respect to the technical specification value (13.7 Kw).
Additionally, an implied FAH can be derived by determining the ratio of the average heat flux assumed in the hot rod and the average heat flux assumed in the core. This results in an implied enthalpy rise peaking factor of approximately 1.95.
8411260214 i841121 PDR ADOCK 05000206 PDR
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Mr. 3. A. Zwolinski
-2 The small break LOCA analysis was performed when the technical specification value for FAH was 1.75. Additionally, the peak linear power assumed is conservative. As discussed in Section 4.3 of the Safety Evaluation for the FAH increase, a reduction in FAH from 1.75 to 1.57 results in a less limiting LOCA situation. Therefore, the small break LOCA analysis is conservative and remains applicable for an FAH of 1.57.
If you have any questions or desire additional information, please call me.
Very truly yours, cc:
E. McKenna, NRC Project Manager B. D. McKenzie, Westinghouse Nuclear Technology Division
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