ML20072F024
| ML20072F024 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/17/1994 |
| From: | Marsh W SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-M71194, TAC-M71195, NUDOCS 9408230173 | |
| Download: ML20072F024 (2) | |
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wAuen c mn,m MANAOf F4 OF #RJC.Lf: AR PitGut A TOAV Ar F AIF153 (794)454-4403 U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C.
20555 Gentlemen:
Subject:
Docket Nos. 50-361 and 50-362 Component Cooling Water System TAC Nos. 71194 and 71195 San Onofre Nuclear Generating Station i
Units 2 and 3
Reference:
(1)
Letter from Harold B. Ray (SCE) to the Document Control Desk dated December 30, 1992;
Subject:
Proposed Technical Specification Change No. NPF-10/15-418, Component Cooling Water Safety Related Makeup System, San Onofre Nuclear Generating Station, Units 2 and 3 (2)
Letter from W. C. Marsh (SCE) to the Document Control Desk dated September 7, 1993;
Subject:
Docket Nos. 50-361 and 50-362 Component Cooling Water System, TAC Nos. 71194 and 71195, San Onofre Nuclear Generating Station, Units 2 and 3 As requested by the NRC Project Manager for San Onofre Units 2 and 3, this letter provides information to the NRC to close the issues related to the Primary Plant Make-Up (PPMU) tank upgrade supporting Proposed Technical Specification Change No. NPF-10/15-418 (PCN-418), Reference (1).
DISCUSSION in Reference (2) Southern California Edison (Edison) reported that the PPMU tank T-056 for Unit 2 was upgraded during the Unit 2 Cycle 7 refueling outage.
This referenced letter also reported that Calculation M-DSC-280 documented the seismic upgrade analyses and American Society of Mechanical Engineers (ASME) code reconciliation, including a detailed explanation of the statistical and fracture mechanics analyses, for the Unit 2 tank.
This analysis and code reconciliation for the Unit 2 PPMU tank was performed because the welding on the Unit 2 PPMU tank shells did not meet the ASME Code requirements.
Therefore, it was necessary to demonstrate the welds were capable of withstanding a Design Basis Earthquake plus other simultaneous loads. Based on the radiography examination results, a statistical analysis was performed to establish the maximum possible defect size with a high confidence level. The statistical analysis was followed by a fracture OUC22 9408230173 940917 I
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Document Control Desk mechanics flaw evaluation that demonstrated the existing defects are acceptable with a substantial factor of safety.
Subsequent to the referenced letter the Unit 3 tank T-055 was upgraded during the Unit 3 Cycle 7 refueling outage. Also, during the outage'T-055 was inspected and similar weld conditions to those of the Unit 2 tank were found.
To disposition these findings a code reconciliation similar to the Unit 2 tank code reconciliation was performed for T-055.
This code reconciliation and the seismic upgrade analysis are documented in Calculation M-DSC-269.
T-055 was originally designed to the American Petroleum Institute (API) -620 Standard, 5th Edition, constructed and tested to the API-650 Standard, 5th Edition, and was classified as Quality Class III and Seismic Category II.
As documented by Calculation M-DSC-269, T-055 was upgraded with physical modifications to meet the requirements of Quality Class-II, Seismic Category I, and the ASME Section III Class 3 Code with the exception of an N-stamp and Code inspection. Materials, design, fabrication, installation, examination, testing, overpressure 3rotection, and welding requirements of the API codes were reconciled with tie requirements-of the ASME Code (1989 Edition with no Addenda).
Consistent with this upgrade, both T-055 and the Unit 2 tank, T-056, were added to the San Onofre ASME Code Section XI testing program.
Also, the administrative controls discussed in the referenced letter will remain in effect until the NRC approves PCN 418.
Please let me know if you have any questions or would like additional information.
4 Very truly yours, llY cc:
L. J. Callan, Regional Administrator, NRC Region IV K. E. Perkins, Jr., Director, Walnut Creek Field Office, NRC Region IV J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 & 3 H. B. Fields, NRC Project Manager, San Onofre Units 2 and 3
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