ML19207C497
| ML19207C497 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 08/14/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19207C495 | List: |
| References | |
| SER-790814, NUDOCS 7909120047 | |
| Download: ML19207C497 (3) | |
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UNITED STATES 3%
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ga j SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT N0. 70 TO FACILITY OPERATING LICENSE N0. DPR-57 GEORGIA POWER COMPANY OGLETHORPE ELECTRIC MEMBERSHIP CORPORATION MUNICIPAL ELECTRIC ASSOCIATION OF GEORGIA CITY OF DALTON, GEORGIA EDWIN I. HATCH NUCLEAR PLANT UNIT N0. 1 DOCKET NO. 50-321 Introduction By letter dated May 22, 1979 as supplemented by letters dated June 4 and 25, 1979, Georgia Power Company (licensee) proposed a change to the Technical Spec-ifications appended to Operating License No. DPR-57 for the Edwin I. Hatch Nuclear Plant Unit No.1.
The change would modify the Limiting Conditions for Operation arid the Surveillance Requirements associated with the Reactor Protection System (RPS) Power Supply to reflect the addition of an electric power monitoring system on the output of each power supply. The actions taken by the licensee are directly related to the Commission's ORDER for modifi-cation of License and the Connission's interim EXEMPTION to certain require-ments of General Design Criterion (GDC-2) of Appendix A to 10 CFR 50, both of which were issued on August 7, 1978.
Backaround During review of Edwin I. Hatch 2 Operating License application, the staff questioned the capability of the Class lE reactor trip system (and other Class lE systems and components powered from the RPS power supply) to accommodate the effects of possible sustained abnormal voltage and frequency conditions from the non-Class lE reactor trip system power supply. These abnomal conditions could be caused by possible, though unlikely, combinations of undetectable single failures and by the effects of earthquakes.
These abnormal conditions could result in damage to the Class lE systems and com-ponents with the attendant potential loss of capability to perform their intended safety function.
The specific concerns were in regard to conformance with GDC-2 (seismic capability) and GDC-21 (single failure).
Since the disign of the RPS power supply for Hatch Unit No. I was identical to Hatch Unit No. ?, the staff, on its cwn initiative, issued an Order for Modification of license and required periodic surveillance on the power supplies in order to allay, at least temporarily, the specific concerns with regard to single failures.
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, Simultaneously, temporary Exemption to GDC-2 was granted until the next refueling outage to permit the licensee time to obtain and install equipment necessary to achieve full conformance with GDC-2. The basis for allowing such an exemption included consideration of:
reported failures due to the seismic events which have been experienced; the unlikelihood of occurrence of the series of undetected failures which would lead to an unsafe condition; and the implementation of surveillance.
Evaluation On January 10, 1979, the licensee met with the NRC to discuss the conceptual design of an electric power monitoring system. The licensee's fomal submittal was dated May 22, 1979. Another meeting was held June 13, 1979. We have reviewed the design details of the licensee's proposal, including electrical drawings and equipment specifications that were provided.
The licensee has proposed to install an electric power monitoring system on each of the three sources of power for the RPS (i.e., M-G sets A and B, and the Alternate Source).
Each system will consist of two identical and redundant channels.
Each channel will include a power monitoring module and a breaker. When abnormal power is detected, the circuit breaker is tripped.
Either channel independently protects the RPS from abnormal electric power.
Each power monitoring module will detect over-voltage, under-voltage, and under-frequency conditions.
The under-voltage and under-frequency monitoring equipment includes time delay features, for which the licensee had proposed settings of 2.15 seconds and 2.25 seconds respectively. We indicated that this delay could not be allowed unless it was shown that no damage from abnormal power would result. The licensee has agreed to set all time delays to zero pending NRC approval of different value(s).
We find that the protection of the RPS is initiated automatically. This protection cannot be lost by any single component failure.
Each channel of the monitoring system is physically and electrically independent of any other channel. The equipment involved is seismically qualified as Category 1 in conformance to IEEE Standard 344-1975.
The design is testable and the licensee has proposed functional testing semi-annually and a calibration frequency of once every refueling outage. Such a frequency is the same as that approved for similar Class lE equipment and has been determined to be adequate.
We have reviewed the Limiting Conditions for Operations specifications and the surveillance specifications and find them adequate.
We conclude that no single component failure can cause the RPS to be exposed to electric power of unacceptable quality such that safety related equipment con-nected to the RPS would not be protected from power which is outside their range of qualification. The equipment involved is qualified such that seismic events are not expected to lead to failures. In view of these considerations, we conclude that the proposed electric power monitoring systems are acceptable.
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. Environmental Considerations We have determined that this amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that this amendment involves an action which is insignificant from the standpoint of environmental impact, and pursuant to 10 CFR Section Sl.5(d)(4) that an environmental impact statement, or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
Conclusion We have concluded that:
(1) because the amendment does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, the amendment does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Cornission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Dated: August 14, 1979 4k 077 0