ML13326A642
| ML13326A642 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/20/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML13326A640 | List: |
| References | |
| TAC-43464, NUDOCS 8105010559 | |
| Download: ML13326A642 (1) | |
Text
Attachment 1 05F UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION REPORT SAN ONOFRE NUCLEAR GENERATING STATION (UNIT 1.)
PRIMARY COOLANT SYSTEM PRESSURE ISOLATION VALVES (WASH-1400, EVENT V) 1.0 Introduction The Reactor Safety Study (RSS), WASH-1400, identified in a PWR an intersystem loss of coolant accident (LOCA) which is a significant contributor to risk of core melt accidents (Event V).
The design examined in the RSS contained in-series check valves isolating the high pressure Primary Coolant System (PCS) from the Low Pressure Injection System (LPIS) piping.
The scenario which leads to the Event V accident is initiated by the failure of these check valves to function as a pressure. isolation barrier.
This causes an overpressurization and rupture of the LPIS low pressure piping which results in a LOCA that bypasses containment.
In order to better define the Event V concern, all light water licensees were requested by 10 CFR 50.54(f) letter,.dated February 23, 1980, to identify valve configurations of concern and prior valve test results, if any.
By letter dated March 14, 1980, the licensee responded to our request and this information was subsequently transmitted to our contractor, the Franklin Research Center for verification that the licensee had correctly identified the subject valve configurations.
2.0 Evaluation In order to prepare the attached Technical Evaluation Report (TER) it was necessary that the contractor verify and evaluate the licensee's response to our February 1980 letter. The NRC acceptance criteria used by Franklin were based on WASH-1400 findings, probabilistic analyses and appropriate Standard Review Plan requirements..With respect to the verification of the licensee's response to our information request, the Franklin evaluation was based on FSAR information, ISI/IST site visit data, and other previously docketed information.
The attached Franklin TER correctly identifies the subject valve configurations.
3.0 Conclusion Based on our review of the Franklin TER we find that the valve configurations of concern have been correctly identified.
Since periodic testing of these PCS pressure isolation valves will reduce the probability of an intersystem LOCA we, therefore, conclude that the requirement to test these valves should be incor porated into the.plant's Technical Specifications.
Dated:
April 20, 1981