ML20049J628
| ML20049J628 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 03/03/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20049J627 | List: |
| References | |
| NUDOCS 8203180517 | |
| Download: ML20049J628 (2) | |
Text
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UNITED STATES
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i NUCLEAR REGULATORY COMMISSION r,
j WASHINGTON. D. C. 20555
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SAFETY EVALUATION PILGRIM NUCLEAR POWER STATION, UNIT 1 DOCKET NO. 50-293 ADE00ACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES Author:
P. Prevatte INTRODUCTION AND
SUMMARY
l Boston Edison Company (BEC0/ licensee) was requested by NRC letter dated August 8,1979 to review the electric power system at Pilgrim Nuclear Power Station, Unit 1.
The review was to consist of:
l a) Determining analytically the capacity and capabilit) of the offsite power system and onsite distributions system to automatically start as well as operate all required loads within their required voltage ratings in the l
event of 1) an anticipated transient, or 2) an accident (such as LOCA) r 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 l
violating the requirements of General Design Criterion 17 (Appendix A to 10 CFR Part 50).
The August 8,1979 letter included NRC 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. BECO responded by letters dated September 24, 1979, October 16,1979, March 28, 1980, November 5,1980 and June 16, 1981, and by referencing previously submitted letters dated November 15, 1976, August 8,1977 and August 24, 1977.
A detailed review and technical evaluation of the submittals was performed by Lawrence Livermore Laboratory (LLL) under contract to the NRC, with general supervision by NRC staff.
This work is reported by LLL in Technical Evaluation Report (TER), " Adequacy of Station Electric Distribution System Voltages, Pilgrim Nuclear Power Station, Unit 1," dated December 1,1981. 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 General Design Criterion (GDC) 5 (" Sharing of Structures, Systems, and Components"), GDC 13 (" Instrumentation and Control"), and GDC 17 (" Electric Power Systems") of Appendix A to 10 CFR 50; IEEE Standart 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 the NRC letter to BECO dated August 8,1979.
l 8203180517 820303 l
PDR ADOCK 05000293 P
. ANALYSIS AND TEST FEATURES BECO analyzed each offsite source to the onsite distributions system under Also included anticipated maximum and minimum voltage and load conditions.
in the analysis was the effects on the Class 1E system when starting a large It has non-Class 1E load (reactor feedwater pump) during a LOCA condition.
been established that the emergency 4160V and 480V loads will operate within allowable limits for the worst cases analyzed.
The voltage analysis was verified by taking measuremer.ts on the Class 1E buses, with the unit operating the main generator and unit auxiliary The comparison showed that the transformers supplying the source of power.
calculated voltages for the Class 1E buses are within -1.56% and +0.24% of This close correlation verifies the accuracy of the the measured voltage.
analysis submitted.
A review of the licensee's submittals indicates that three sources of offsite power (startup transformers, shutdown transformer, and unit auxiliary transformer, with isolation from the main generator) are available to the Our review of the licensee's submittals indicates onsite distribution system.
that the likelihood of simultaneous failure of all onsite power sources This is in compliance under operating and postulated conditions is minimized.
with GDC 17 and is therefore acceptable.
I CONCLUSIONS We have reviewed the LLL Technical Evaluation Report and concur in the findings that:
BECO has provided verified voltage analyses to demonstrate that Class 1E 1.
equipment voltages remain within acceptable operating limits for the postulated worst case conditions involving electrical load and grid voltages.
BEC0's reaffirmation of compliance to GDC 17 is ac:eptable.
2.
The voltage analysis was verified by test and the close correlation showed 3.
the analysis to be accurate.
There is reasonable assurance that spurious separation from the offsite 4.
sources due to starting of a large non-Class 1E load or the bulk starting of Class 1E loads during a LOCA will not occur.
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