ML13331B301
| ML13331B301 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 01/03/1991 |
| From: | Nandy F SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-88-011, IEB-88-11, NUDOCS 9101080080 | |
| Download: ML13331B301 (3) | |
Text
Southern California Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 January 3, 1991 F. R. NANDY TELEPHONE MANAGER. NUCLEAR LICENSING (714) 454-4504 U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C.
20555 Gentlemen:
Subject:
Docket No. 50-206 NRC Bulletin No. 88-11, Pressurizer Surge Line Thermal Stratification San Onofre Nuclear Generating Station, Unit 1 This letter reschedules our commitment regarding action item 1.d of NRC Bulletin No. 88-11, "Pressurizer Surge Line Thermal Stratification."
We were scheduled to provide our response to the action item by January 4, 1991.
However, our review of the Westinghouse generic response has revealed that an entirely new plant specific analysis will be required. The new due date and our justification for continued operation in the interim are presented below.
Background
Action item 1.d of the bulletin, which is dated December 20, 1988, requires all licensees of operating PWR's to update their stress and fatigue analyses for the pressurizer surge line to ensure compliance with applicable Code requirements. It requires this analysis to be completed no later than two years after receipt of the bulletin (January 4, 1991).
On November 8th and 9th of 1990, Westinghouse met with the NRC staff on behalf of the owners group formed to resolve this issue and informed them that a number of utilities will not be able to meet their due date regarding action item 1.d. The NRC staff responded that a request for extension would be required from each of these utilities, including an explanation for the extension, the revised due date and a statement that continued plant operation is justified. This information is provided below for SONGS 1.
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Document Control Desk January 3, 1991 Explanation for Extension Our review of the Westinghouse generic analysis revealed that SONGS 1 is not enveloped by this analysis. Westinghouse issued its "Generic Detailed Analysis for Pressurizer Surge Line Thermal Stratification," WCAP-12639 (Proprietary) and WCAP-12640 (Non-Proprietary) in June 1990. These reports categorized San Onofre Unit 1 with other Westinghouse plants with similar operating conditions and performed a generic ASME Code stress and fatigue analysis. The results of this analysis indicated that the surge lines comply with the ASME Code requirements. Utilities were expected to demonstrate that their plant is covered by the results of the Westinghouse analysis.
SCE received the reports in August 1990 and immediately initiated the plant specific analysis. Our calculations showed that the judgements used by Westinghouse in the generic analysis are not entirely bounding for SONGS 1.
Specifically, we found that the plant configuration assumed by Westinghouse is not conservative for SONGS 1.
Because of this unforeseen problem, our work scope has significantly increased. To respond to action item 1.d., we must perform independent plant specific calculations, instead of simply demonstrating that SONGS 1 is covered by the generic analysis.
Revised Due Date We expect to complete our fatigue analysis and submit our response to action item 1.d based on this analysis by November 30, 1991.
Justification for Continued Operation We submitted a Justification for Continued Operation (JCO) for at least 10 additional plant heatup/cooldown cycles with a letter dated June 1, 1989.
This information was submitted in response to action item 1.b of the bulletin.
By its July 31, 1990 letter, the NRC approved the JCO for short-term application. This JCO was based on a bounding analysis performed by Westinghouse, using input from 55 domestic PWR's. We have reviewed the JCO and have determined that its conclusions do not need to be modified. Since submitting the JCO, we have had four heatup/cooldown cycles. This indicates that the JCO should be valid for at least six more heatup/cooldown cycles (estimated to cover at least two more years of plant operation).
Document Control Desk January 3, 1991 Based on the above, it is acceptable for SCE to continue power operation until our forthcoming response to action item 1.d. of the bulletin has been submitted to and reviewed by the NRC.
If you have any questions, please call me.
Very truly yours, cc: J. B. Martin, Regional Administrator, NRC Region V C. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2 and 3 C. D. Townsend, NRC Resident Inspector, San Onofre Unit 1