ML20117D705
| ML20117D705 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/26/1996 |
| From: | Rainsberry J SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9608290041 | |
| Download: ML20117D705 (2) | |
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fCf Southem Califomia Edison Company P. O. BOX 128 SAN CLEMENTE. CALIFORNI A92674-0128 August 26, 1996 A ' naiNssEnny reterso~=
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U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C.
20555 Gentlemen:
Subject:
Docket Nos. 50-361 and 50-362 Power Supply for Shutdown Cooling System Isolation Bypass Valves 2
San Onofre Nuclear Generating Station Units 2 and 3 4
Reference:
July 12, 1996, Letter from Mel B. Fields (NRC) to Harold B. Ray (Edison);
Subject:
Inverter Design for Shutdown Cooling System i
Isolation Bypass Valves This letter responds to the Safety Evaluation Report (SER) issued by the NRC on July 12, 1996 (Referenced), by providing the requested power supply permanent solution and its implementation schedule.
In the referenced SER the NRC concluded that the current design of the power supply (inverters) to the shutdown cooling system does not comply with a
applicable industry guidance, and that the modifications (the installation of 1
two additional selectable fuses per inverter) were not acceptable as a permanent solution. The NRC further concluded that the modifications did provide an acceptable level of safety in the interim until a pennanent i
solution could be implemented.
Southern California Edison (Edison) will either replace the inverters with DC/AC motor-generator sets or larger inverters, or replace the current valve actuator motor with a DC actuator motor.
Edison will engineer this change in accordance with its design process. The schedule for this design change includes the following:
1)
Conceptual engineering to address all issues and to validate the acceptability of the proposed design; the estimated time is 4 months.
This includes Edison internal review and approval, finding a reliable and qualifiable motor / generator set, qualified inverter, or environmentally qualified DC actuators.
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2)
Prepare the design change package and procure the material l
(including an estimated 6 months for manufacturing and delivery);
the estimated time is 10 months 1
This-includes preparation of design specifications; evaluation of supplier proposals; preparation of design changes; calculation -
changes; MOV design capability and calculation changes, and evaluation of impact on the Updated Final Safety Analysis Report, Design Basis Documentation, and Technical Specifications. This also includes the preparation of a submittal to the NRC and subsequent approval, if necessary.
3)
Final Design Engineering Review and Approval Phase; the estimated time is 2 months This includes multi-discipline review and approval (Station Technical / Construction / Maintenance / Operations review and approval) i Because the total time estimated to complete the design change process is i
16 months, Edison will schedule implem ntation of the design change to occur during the Cycle 10 refueling outage for each unit.
-If you have any questions on this matter, please call me.
I Sincerely, O
cc:
L. J.' Callan, Regional Administrator, NRC Region IV J. E. Dyer, Director, Division of Reactor Projects, Region IV K. E. Perkins, Jr., Director, Walnut Creek Field Office, NRC Region IV 1
J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 & 3 M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3
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