ML13310B408
| ML13310B408 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 05/17/1984 |
| From: | Medford M SOUTHERN CALIFORNIA EDISON CO. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TAC-42131, NUDOCS 8405210324 | |
| Download: ML13310B408 (2) | |
Text
Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 M.O. MEDFORD TELEPHONE MANAGER. NUCLEAR LICENSING May 17, 1984 (213) 572-1749 Director, Office of Nuclear Reactor Regulation Attention: D. M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Gentlemen:
Subject:
Docket No. 50-206 Clarification to Amendment No. 115 San Onofre Nuclear Generating Station Unit 1
Reference:
Letter K. P. Baskin (SCE) to H. R. Denton (NRC), December 5, 1983, Amendment No. 115 By the referenced letter, Southern California Edison Company submitted Amendment No. 115 to Provisional Operating License No. DPR-13 for the San Onofre Nuclear Generating Station, Unit 1. Amendment No. 115 consisted of Proposed Change No's. 128 and 129 to the Technical Specifications.
This letter is to submit a clarification regarding paragraph 3.8.A.3(a) of Proposed Change No. 128. The NRC staff has questioned the basis for selecting a flow rate of >400 gpm through the residual heat removal system, during Mode 6 operation when there is high water level in the refueling pool and the reactor vessel head has been removed. The basis for this particular number is discussed in the following paragraphs.
The minimum flowrate of 400 gpm was derived from boron stratification considerations. A Westinghouse evaluation concludes that 400 gpm provides sufficient turbulent mixing in the active pipe to prevent the stratification phenomenon. In addition, it is our conclusion that this 400 gpm flow provides the necessary turbulent mixing to minimize the effects of any boron dilution incident.
With regard to decay heat removal, it is clear from the Basis given in Proposed Change No. 128 that it is not necessary to specify a certain number of gallons per minute of RHR flow as a permanent requirement for the entire refueling operation. It is only necessary to provide sufficient circulation that the water in the reactor pressure vessel remains below 1400F. This is quite effectively achieved by monitoring the RCS/RHR temperatures, as required by the plant procedures. The San Onofre Unit 1 procedures specifically require that the water temperature in the RHR return line from the.RCS be recorded and displayed continuously in the control room.
940521O324 940517 PDR ADOCK 05000206.*
P
-PDR'
Mr. D.
May 17, 1984 In addition, Table 4.1.1, Item 5 of the Technical Specifications requires a channel check once per shift of the RCS temperature measuring instrumentation. These methods are considered adequate to ensure that the required cooling flow is available and Mode 6 temperature conditions are not exceeded.
If you have any further questions, please contact me.
Very truly yours, cc:
J. B. Martin, Regional Administrator, U.S. NRC Region V J.. 0. Ward, Chief Radiological Health Branch State Department of Health Services A. E. Chaffee (USNRC Resident Inspector, Units 1, 2 and 3)
USNRC Document Control Desk (Washington, D.C. 20555)