ML13309A100
| ML13309A100 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 02/20/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML13309A098 | List: |
| References | |
| NUDOCS 9102250322 | |
| Download: ML13309A100 (2) | |
Text
oft' REG UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 142 TO PROVISIONAL OPERATING LICENSE NO. DPR-13 SOUTHERN CALIFORNIA EDISON COMPANY SAN DIEGO GAS AND ELECTRIC COMPANY SAN ONOFRE NUCLEAR GENERATING STATION, UNIT NO. 1 DOCKET NO. 50-206
1.0 INTRODUCTION
By letter dated December 21, 1990, Southern California Edison Company (SCE) requested a change to the Technical Specifications (TS) appended to Provisional Operating License No. DPR-13 regulating operation of the San Onofre Nuclear Generating Station, Unit No. 1, located in San Diego County, California.
2.0 DISCUSSION In a letter dated December 21, 1990, SCE submitted a request to revise the San Onofre Unit 1 Technical Specifications (TS) to incorporate changes to maintenance and surveillance requirements that were necessitated by the addition of a redundant isolation valve on the outlet of the Volume Control Tank. The redundant valve was added during refueling outage 11 to reduce the likelihood of a single component failure from disabling both primary system charging pumps.
The associated TS changes consist of an addition to Section 3.3.1.B to regulate maintenance of the redundant isolation valves and the deletion of surveillance requirement 11 from Table 4.1.2. The surveillance requirement is associated with an electrical power transfer switch that was functionally replaced by the second isolation valve. The transfer switch was removed from the system as part of the modification.
3.0 EVALUATION During an Emergency Core Cooling System single failure analysis the licensee identified a potential scenario that could cause both charging pumps to fail following failure of any one of several components associated with the Volume Control Tank. During the postulated event, a charging pump would pump all the water out of the VCT and hydrogen overpressure gas from the tank would fill suction pipes to both charging pumps. Both charging pumps could become disabled from vapor binding until the hydrogen gas was manually vented at the pump.
Vapor binding of charging pumps could occur following failure of components associated with the following: (1) VCT level instrumentation that transfers 91 O225O322 910220 PDR ADOCK o5o00206 PDR6
-2 charging pump suction from the VCT to the Refueling Water Storage Tank (RWST) on low-low level in the VCT or (2) closure of the VCT isolation valve (MOV-1100C) on receipt of a low-low level signal.
To decrease the likelihood of the postulated failures described above, the licensee added a second valve (MOV-1100E) in series with MOV-1100C. The second valve installation includes independent VCT level instrumentation and an independent electric power source. An automatic electric power transfer switch which had been used to provide two sources of power for MOV-1100C was rendered superfluous by the modification and was removed.
Two changes were made to the TS to reflect the hardware modifications: (1)
Section 3.3.1.B.8 was added to permit removing either valve MOV-1100C or MOV-1100E from service for not longer than 72 consecutive hours to perform maintenance. This TS provision for maintenance of redundant components is a typical feature incorporated in the Standard Technical Specifications and is appropriate for this specific case. (2) Table 4.1.2 was revised to delete surveillance requirements for the MOV-1100C transfer switch that was removed by the modification.
An additional TS revision to correct an editorial error is also included in this amendment. The editorial error was inadvertently introduced by TS Amend ment 134. Amendment 134 deleted item 10 from Table 4.1.2.- The frequency for surveillance requirements of items 11, 12, and 13 in Table 4.1.2 was listed as "Same as Item 10 above". Included is this amendment is a restatement of the surveillance frequencies that were inadvertently omitted when item 10 was deleted.
4.0 ENVIRONMENTAL CONSIDERATION
This amendment involves changes with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20, or changes a surveillance requirement. The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, this amendment meets the eligibility criteria for categorial exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
5.0 CONCLUSION
We have concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: G. Kalman Dated: February 20, 1991