ML13317A675
| ML13317A675 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/28/1981 |
| From: | Moody W Southern California Edison Co |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0098, RTR-NUREG-0737, RTR-NUREG-737, RTR-NUREG-98, TASK-03-06, TASK-2.B.4, TASK-3-6, TASK-RR, TASK-TM NUDOCS 8110010348 | |
| Download: ML13317A675 (10) | |
Text
Southern California Edison Company P. 0.
BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 W. C. MOODY TELEPHONES MANAGER, NUCLEAR LICENSING September 28, 1981 (213) 572-1817 (213) 572-1806 Director, Office of Nuclear Reactor Regulation Attention: D. M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing U. S. Nuclear Regulatory Commission CO Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 SEP Topic 111-6 Seismic Design Considerations a
San Onofre Nuclear Generating Station Unit 1 In meetings with the NRC Staff on July 30 and September 14, 1981, we discussed certain modifications to the north extension and west heater platform of the turbine building. In a meeting on September 25, 1981, additional modifications to the north extension column connections were discussed. The purpose of this letter is to document our commitments with respect to modification of these structures.
The north extension and west heater platform will be modified by adding structural bracing to some of the building columns. These modifications will be implemented by June 1, 1982 or we will shut down the plant until the modifications are complete.
On the north extension the connections of the five southernmost columns will be modified to ensure that these connections are capable of developing the full plastic moment of the columns. Details of these modifications are shown on the enclosed-drawings. The three northernmost columns will not be modified, as discussed with the NRC Staff, since deflection of these columns is limited by adjacent structures such that the columns will not go inelastic. Modifications to the connections of the five columns are scheduled to be implemented by October 18, 1981.
P dc 500206
Mr. D. M. Crutchfield
-2 With the modifications to the connections as discussed above, it is concluded that the north extension will be capable of withstanding an earthquake in excess of 0.67g Housner without structural failure. This conclusion is based on the provisions for ductility of structures in NUREG/
CR-0098, Development of Criteria for Seismic Review of Selected Nuclear Power Plants. Following the addition of the structural bracing to the north extension and west heater platform, these structures will be capable of withstanding an earthquake in excess of 0.67g Housner with no consideration of ductility.
The modifications to the north extension connections ensure the
.availability of the systems and equipment required to implement what has been identified as the alternate means for removing decay heat which was described in Enclosure 3 to our August 11, 1981 letter. This alternate means is comprised of feeding the primary system using the charging pumps and the long term recirculation lines and bleeding the primary system through the pressurizer power operated relief valves. As discussed with the NRC Staff, analyses have been performed to demonstrate that there is sufficient time for the operator to implement the required actions. At the September 25, 1981 meeting, the NRC Staff expressed an interest in knowing whether procedures exist for this feed and bleed operation. In response to this question we advised the staff that actions taken in response to Item II.B.4 of NUREG 0737 include the creation of Station Operating Instruction S01-1.8-1, entitled Inadequate Core Cooling, which specifies the use of such a feed and bleed procedure under conditions of inadequate core cooling. This procedure was implemented in April 1981.
If you have any additional questions on this matter, please let me know.
Subscribed on this _ __ day of 1981.
Very truly yours, By W. C. Moody Manager, Nuclear Licensing AGNES CRABTREE 40 NOTARY PUBLIC - CALIFORNIA PRINCIPAL OFFICE IN LOS ANGELES COUNTY Subscribe nd sw orn to pefore me this* 4f dy of.y 1981.
My Commission Exp. Au.2,098 Notar ublic in and for the County of Los Ageles, State of California
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