ML13309A257
| ML13309A257 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/26/1992 |
| From: | Rosenblum R SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9207010046 | |
| Download: ML13309A257 (2) | |
Text
Southern Caifornia Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 R. M. ROSENBLUM June 26, 1992 TELEPHONE MANAGER OF (714) 454-4505 NUCLEAR REGULATORY AFFAIRS U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Refueling Water Storage Tank Evaluation Update San Onofre Nuclear Generating Station Unit 1 (SONGS 1)
Reference:
Letter, R. Ornelas, SCE to NRC, "Request for Relief from ASME Section XI Articles Applicable to Refueling Water Storage Tank Leakage," April 26, 1992 Enclosed is an update of the SONGS 1 Refueling Water Storage Tank (RWST) evaluation. The original evaluation was provided to the NRC as Attachment A to our request for relief (see reference) from the repair provisions of Article IWA-5250 of Section XI of the ASME Boiler and Pressure Vessel Code as applicable to the RWST. In that submittal, we had committed to update the RWST evaluation once the calculation results were finalized, and as more current RWST inspection data became available.
The enclosed evaluation is an updated version of the Attachment A included in the referenced submittal.
It contains results of a detailed stress evaluation utilizing tank corrosion data obtained subsequent to the previous submittal.
In addition, the enclosed document contains information pertaining to areas of NRC concern, such as the potential for accelerated corrosion due to crevice cracking, leakage into the tank foundation area, and results of a UT scan test to determine the size of the smallest detectable defect. These changes are denoted by change bars on the margin of the enclosed document.
The format of the previously submitted evaluation document has been retained with the exception of the "Analysis Results" section. This section has been essentially replaced by a newly created Summary Report containing results of the new stress evaluation. The Summary Report is included as an attachment to the enclosure.
9207010046 920626 10L PDR ADOCK0 PPDRI/
Document Control Desk June 26, 1992 Results of the new evaluations using the reduced tank shell thickness show that the tank continues to meet the required seismic and structural design criteria, that the tank's ability to perform its safety functions will not be compromised by the defects or seepage, and that the tank continues to be operable. Therefore, the conclusion reached in our earlier submittal that the tank requires no repairs at this time remains valid.
We plan to permanently shutdown SONGS 1 following Cycle 11 operation, and maintain the spent fuel in the Unit 1 spent fuel pool following the shutdown.
We are currently evaluating the need for the RWST to perform a long-term shutdown function. If the tank is determined to be needed, repairs will be performed as required.
Please contact me if you have any questions regarding the enclosure, or if you require any additional information.
Very truly yours, Enclosure cc:
J. B. Martin, Regional Administrator, NRC Region V George Kalman, NRC Senior Project Manager, San Onofre Unit 1 J. 0. Bradfute, NRC Project Manager, San Onofre Unit 1 C. W. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2&3 bcc:
(See attached sheet)