ML13317A892
| ML13317A892 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 02/24/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML13317A891 | List: |
| References | |
| NUDOCS 8203050460 | |
| Download: ML13317A892 (4) | |
Text
ENC SURE-1 SAFETY EVALUATION SAN ONOFRE NUCLEAR GENERATING STATION UNIT 1 DOCKET NO. 50-206 ADEQUACY OF STATION-ELECTRIC DISTRIBUTION SYSTEM VOLTAGES INTRODUCTION AND
SUMMARY
Southern California Edison Company was requested by NRC letter dated August 8, 1979 to review the electric power system at San Onofre Nuclear Generating Station Unit 1. The review was to consist of:
a)
Determining analytically the capacity and capability of the offsite power system and onsite distribution system to automatically:
start as well as operate all required loads within their required voltage ratings in the event of 1) an antic-ipated transient, or
- 2) an accident (such as LOCA) without manual shedding of any electric loads.
b)
.Determining if there are any events or conditions which could result in the simultaneous or, consequential loss of both required circuits from the offsite network to the onsite electric distribution system and thus violatina the requirements of GDC 17.
The August 8.4 1979 letter included staff guidelines for performing the required voltage analysis and the licensee was further required to perform a test in order to verify the validity of the analytical results. SCE responded by letters dated May 1, 1980 and August 19, 1981.
8203050460 820224 PDR ADOCK 05000206
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- PDR,
- 30
-3 However, until Units 2 and 3 become operational, 224 kv is the maximum anticipated grid.voltage. The Class 1E loads that are designed to automatically start and operate during a LOCA are normally loaded through a sequencer.
For conservatism.the analysis was based on bulk loading all the Class 1E LOCA loads, and two 3500 hp feedwater pumps onto. the onsite distribution system. The results of the analysis indicate that the 4160 volt and 480 volt emergency. loads will operate within allowable limits with.single unit and three unit operation when supplied from the 230 kv grid.
The licensee has submitted a detailed description of the tests which will be performed to verify the voltage analysis.
The proposed testing program conformis to staff requirements.
The tests will be conducted during an outage scheduled to begin in March 1982 and the results of the tests will be provided to NRC upon completion.
CONCLUSIONS We have reviewed the LLL Technical Evaluation Report and concur in the findings that:
(1) SCE has"provided voltage analysis to demonstrate that Class IE equipment voltages will remain within acceptable operating limits for the postulated worst case grid voltage conditions.
-4 (2) The tests proposed by SCE will verify the voltage analysis accuracy.
(3), SCE's reaffirmation of compliance to GDC 17'requirements is acceptable.
(4) The two percent overvoltage condition that could exist under minimum bus loading and maximum grid voltage is not considered significant since any loading of equipment on the Class 1E buses will reduce the voltage to acceptable levels.
We, therefore, find the San Onofre Nuclear Generating Station Unit 1 design to be acceptable with respect to adequacy of station.electric distribution system voltage subject to the verification testing required above.
We shall address the verification testing in a supplement to this-report.
-2 Avdetailed review and technical evaluation of the submittals was performed by LLL under contract to the NRC, with general supervision by NRC staff.
This work is reported by LLL in Technical Evaluation Report (TER),
"Ade'quacy of Station Electric Distribution System Voltages, San Onofre Nuclear Generating Station - Unit 1," dated January 14, 1982 (attached).
We have reviewed this report and concur in the conclusions that the offsite power system and the onsite distribution system are capable of providing acceptable voltages for worst case station electric load and grid voltages.
EVALUATION CRITERIA The criteria used by LLL in this technical evaluation of the analysis includes GDC 5 ("Sharing of Structures, Systems, and Components"),
GDC 13 ("Instrumentation and Control"),
GDC 17 ("Electric Power Systems")
of Appendix A to 10 CFR 50; IEEE Standard 308-1974 ("Class 1E Power Systems for Nuclear Power Generating Stations"), ANSI C84.1-1977
("Voltage Ratings for Electric Power Systems and Equipment -60 Hz"),
and the staff positions and guidelines in NRC letter to SCE dated Aucust 8, 1979.
ANALYSIS AND TEST FEATURES SCE analyzed each offsite power source to the onsite distribution system under maximum and minimum load conditions with the 230 kv grid at maximum and minimum anticipated grid voltages of. 234.5 kv and 217.8 kv The maximum voltage is based on all three units operating..>