ML13326A848
| ML13326A848 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 05/01/1992 |
| From: | Ray H SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML13326A849 | List: |
| References | |
| NUDOCS 9205040220 | |
| Download: ML13326A848 (2) | |
Text
Southern California Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 HAROLD B. RAY TELEPHONE SENIOR VICE PRESIDENT May 1, 1992 714-4S8o4400 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Amendment Application No. 205 Moderator Temperature Coefficient Change Request San Onofre Nuclear Generating Station Unit 1 (SONGS 1)
Enclosed is Amendment Application No. 205 requesting changes to Appendix A to the Facility Operating License No. DPR-13 for SONGS 1, Technical Specifications. The proposed changes are necessary to resolve an inconsistency between the stated Technical Specification basis for Moderator Temperature Coefficient (MTC) and the MTC value used in the Main Steam Line Break (MSLB) event analysis. The changes will ensure that the MTC Technical Specification bounds all accidents including the MSLB event, as stated in the basis for MTC Technical Specification.
Amendment Application No. 205 (consisting of Proposed Change No. 255) requests changes to Technical Specifications Section 3.9, "MODERATOR TEMPERATURE COEFFICIENT (MTC)," Section 3.3.3, "MINIMUM BORON CONCENTRATION IN THE REFUELING WATER STORAGE TANK (RWST) AND SAFETY INJECTION (SI) LINES AND MINIMUM RWST WATER VOLUME," and Section 3.5.2, "CONTROL ROD INSERTION LIMITS."
BACKGROUND During recent investigative work on UFSAR Chapter 15 reanalysis, SCE discovered an inconsistency between the stated basis for the MTC limit in Technical Specification 3.9 and the MSLB as analyzed for Cycle 11.
In accordance with their standard analysis methodology for evaluating MSLB events, Westinghouse used an MTC value for MSLB that was less limiting than the Technical Specification limit.
The Westinghouse methodology establishes the MTC for MSLB by using core design limits on fuel burnup. This is based on the assumption by Westinghouse that the MTC Technical Specification is not intended to apply to the MSLB event.
Our position is that the MTC limit in the Technical Specification should bound all events including the MSLB event. We have discussed the identified inconsistency and our approach for its resolution with the NRC.
The NRC has concurred with our position, and has directed us to submit the amendment 92050402A 02000206 PDR ADPDR
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Document Control Desk
-2 application requesting the applicable changes to the Technical Specification.
In the interim, we have taken appropriate measures to ensure that plant operation remains within the licensing basis using our conservative approach.
CHANGES TO TECHNICAL SPECIFICATIONS The proposed change to Technical Specification 3.9 involves a reduction to the current end-of-cycle MTC limit.
To accommodate this revision to the MTC value, changes are also necessary to Technical Specification limits for safety injection line minimum boron concentration and shutdown margin. These proposed changes are discussed in detail in the enclosed amendment application. A Westinghouse report which contains results of calculations using the revised MTC value has not yet been issued, and will be submitted to the NRC by May 15, 1992.
We request that the NRC act on the enclosed amendment application by July 15, 1992. The revised MTC limit is currently being controlled administratively, and is expected to be exceeded in late July 1992.
NRC action on this amendment request by July 15, 1992 will preclude a plant shutdown in late July, based upon our conservative interpretation of the Technical Specifications. We are prepared to discuss this matter further with the NRC staff and to provide any additional information that may be necessary to facilitate the expedited approval.
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