ML13317A623
| ML13317A623 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/01/1981 |
| From: | Moody W Southern California Edison Co |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-05-11.A, TASK-5-11.A, TASK-RR NUDOCS 8106050355 | |
| Download: ML13317A623 (2) | |
Text
Southern California Edison Company P. 0.
BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD, CALIFORNIA 91770 W. C. MOODY TELEPHONES MANAGER, NUCLEAR LICENSING (213) 572-1817 June 1, 1981 (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 Washington, D.C. 20555 Gentlemen:
Subject:
SEP Topic V-11.A San Onofre Nuclear Generating Station Unit 1 Your letter dated January 7, 1981, forwarded a revised evaluation of SEP Topic V-11.A, Electrical, Instrumentation and Control Features for Isolation of High and Low Pressure Systems. Although your letter made no reference to our letter of September 22, 1980, it is assumed that the comment provided in that letter had been considered in the preparation of the revised evaluation.
The revised evaluation still does not accurately describe the plant design. Therefore, enclosed is a proposed redraft of the first paragraph on page 4 of the revised evaluation. Additional comments are also provided in the enclosure.
If you have any questions on this matter, please let me know.
Very truly yours, Enclosure 80605o555
ENCLOSURE V-11.A Electrical, Instrumentation and Control Features for Isolation of High and Low Pressure Systems.
- 1. The first paragraph on page 4 of the evaluation should be revised to read as follows:
"The long-term recirculation system uses the charging pumps in series with the recirculation pumps to provide water from the containment sump to each RCS cold leg.
Isolation is provided by an MOV in each of the three branches. These MOVs are in series with the RCP seal injection flow control valves. In addition, there is a check valve at the discharge of each of the charging pumps. The MOVs are opened using a manual switch and have no interlocks to prevent opening when RCS pressure is above SIS design pressure. The flow control valves are normally open during operation to provide seal injection to the RCPs.
All lines are designed for full RCS pressure."
- 2. The purpose of this SEP topic is to ensure proper isolation of systems with a lower pressure rating than the RCS. As noted in comment 1 above, the recirculation path from the charging pump discharge is designed to RCS pressure. In fact, during normal operation, these lines are pressurized to RCS pressure. Therefore, this system should not be included in the scope of this topic.
- 3. Although the description of the Chemical and Volume Control System (CVCS) on pages.4 and 5 of the evaluation is correct, the conclusions of the evaluation are not appropriate. The CVCS is operated continuously during normal operations. As such, the piping is open to RCS pressure on a continuous basis. The letdown portion of the system is orificed inside containment. These orifices prevent RCS pressure from affecting the low pressure portions of the system. Moreover, downstream of the orifices is the pressure relief valve RV 206 which relieves to the pressurizer relief tank inside containment. There is therefore, no need for pressure interlocks on the letdown valves, since CVCS overpressurization is prevented by the system design.
The discharge of the CVCS is designed for RCS pressure. It is therefore, not a low pressure system and should not be addressed as part of this topic evaluation.