ML20216B969
| ML20216B969 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 03/06/1998 |
| From: | Nunn D SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20216B974 | List: |
| References | |
| NUDOCS 9803130234 | |
| Download: ML20216B969 (3) | |
Text
l < N' som m m ure -
l B
EDISON Vice President l
An EDISONINTLRNATIONAL Company March 6, 1998 U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C.
20555 Gentlemen:
Subject:
Docket Nos. 50-361 and 50-362 Amendment Application Nos. 175 and 161 Proposed Change Number 490 Change to Technical Specification 3.4.12,1
" Low Temperature Overpressure Protection (LTOP)"
San Onofre Nuclear Generating Station, Units 2 and 3
References:
- 1. NRC Inspection Report IR-95-201, December 21, 1995 2.
Letter from Mel B. Fields (NRC) to H.B. Ray (SCE),
dated July 12, 1996;
Subject:
Inverter design for Shutdown Cooling System Isolation Bypass Valves
- 3. Letter from Jack L. Rainsberry (SCE) to the Document Control Desk (NRC), dated August 26, 1996;
Subject:
Docket Nos. 50-361 and 50-362, Power Supply to Shutdown Cooling System Isolation Bypass Valves, i
San Onofre Nuclear Generating Station, Units 2 and 3 i
Thisletteristo-informtheNRCoftheSouthernCaliforniaEdison(SCE)
Company's plans to replace the shutdown cooling (SDC) system isolation bypass valve inverters with transfer switches and to request a License Amendment to eliminate the reference to the inverters in Technical Specification (TS) 3.4.12.1 " Low Temperature Overpressure Protection (LTOP) System."
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During the weeks of October 16 and October 23, 1995, the NRC's Office of Nuclear Reactor Regulation completed the second phase of an Integrated Performance Assessment of the San Onofre Nuclear Generating Station, Units 2 A
and 3.
This phase of the assessment consisted of on-site observations by a team of eight individuals in the areas of safety assessment / corrective action, operations, engineering, maintenance, and plant support.
The~results of the on-site assessment were integrated with those obtained during the team's preliminary in-office documentation review and were summarized in NRC Inspection Report IR 95-201, dated December 21, 1995, Reference 1.
A weakness identified in the Inspection Report was the licensee had not adequately resolved an issue associated with the capacity of the inverters for the shutdown cooling bypass valves.
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Document Control Desk ~,
By Reference 2, on July 12, 1996, the NRC issued a Safety Evaluation Report (SER),." Inverter Design for Shutdown Cooling System Isolation Bypass L
Valves." For the reasons detailed in the SER, the staff concluded that the t
l current design of the inverters does not comply with applicable industry I
guidance, and the licensee's modifications are not acceptable as a permanent solution. The staff further concluded that the steps taken by the licensee to improve the reliability of these inverters, primarily the installation of two l
additional selectable fuses per inverter, provides.an acceptable level of l,
safety in the interim until a permanent solution can be implemented.
In the letter dated August 26, 1996, Reference 3, SCE committed to either replace the. inverters with AC/DC motor-generator sets or with larger inverters, or to replace the current valve actuator with a DC actuator motor.
However, after further consideration and evaluating several options, SCE decided to install manual transfer switches to provide selectable AC power to l
l the SDC system isolation bypass valves HV9377 and HV9378. A detailed discussion of this change and the preliminary 10 CFR 50.59 safety evaluation is included as Attachment F to the enclosed License Amendment Request.
Amendment Reauest Enclosed are Amendment Application Numbers 175 and 161 to Facility Operating Licenses NPF-10 and NPF-15, respectively, for the San Onofre Nuclear Generating Station Units 2 and 3.
These amendment applications consist of Proposed Change Number 490 (PCN-490). PCN 490 is a request to revise TS j
3.4.12.1~to'not mention the inverter since it is being eliminated. The i
associated Bases change to B 3.4.12.1 is included for your information.
SCE requests approval of Amendment Application Numbers 175 and 161 by December 1,1998, to support replacing the SDC System Isolation Bypass Valve inverters with manual switches during the Cycle 10 refueling outages.
Currently, the Unit 2 Cycle 10 refueling outage is scheduled to start in December,1998 and the Unit 3 Cycle 10 outage is scheduled to start in March, 1999.
l l
Because this Technical Specification change is connected to a plant l
modification, SCE requests this amendment be issued effective at Unit 2 upon removing the SDC system inverters from Unit 2, and effective at Unit 3 upon l
removing the SDC system inverters from Unit 3.
Implementation is requested to be within 30 days of the effective date or prior to restoring power to HV9337 or HV9338 following the installation of the manual transfer switches for each unit, whichever is the shorter time.
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Document' Control Desk If you have any questions or would like additional information on this subject,- please let me know.
Sincerely, i
~ C.
Dwight E. Nunn Vice President Enclosure cc:
E. W. Merschoff, 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 Oneire Units 2 & 3 M. B. Fields, NRC Project Manager, San Onofre lir,its 2 and 3 S. Y. Hsu, Department of Health Services, Radf alogic Health Branch
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