ML20023A878
| ML20023A878 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 09/24/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20023A871 | List: |
| References | |
| NUDOCS 8211010012 | |
| Download: ML20023A878 (2) | |
Text
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UNITED STATES e,
t, NUCLEAR REGULATORY COMMISSION j
,,i WASHINGTON, D. C. 20555 e
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 76 TO FACILITY OPERATING LICENSE NO. OPR-39 COMMONWEALTH EDISON COMPANY ZION STATION,' UNIT 1 DOCKET NO. 50-295 Introduction By telecopied letter dated September 23, 1982, the Comonwealth Edison Company (the licensee) requested a temporary change to the Technical Specifications appended to Facility Operating License No. DPR-39 for the Zion Station, Unit No. 1.
The change would allow the 1B charging pump to be inoperable for an additional three day period (until 1440 hours0.0167 days <br />0.4 hours <br />0.00238 weeks <br />5.4792e-4 months <br /> on September 29, 1982).
The current Technical Specifications allow one of the two centrifugal charging pumps, also used for high head safety injection following an accident, to be inoperable for seven days. The 1B pump was declared inoperable at 1440 hours0.0167 days <br />0.4 hours <br />0.00238 weeks <br />5.4792e-4 months <br /> on September 19, 1982 due to the pump shaft failure. The licensee has been working two 10 hour1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> shifts each day to repair the pump but it is projected that an additional three days will be required to install a replacement shaft and test the pump.
Discussion The Zion ECCS includes low pressure pumps, Safety Injection (SI) pumps (1500 psig shut off head) and high head pumps (centrifugal charging pumps). The t
plants FSAR small break LOCA analyses included credit for one SI pump and one high head ECCS pump..
For very small breaks (pressure remaining above 1500 psig) the SI pumps are not called upon.
For larger, small breaks (1200 to 600 psig) both the SI pump and the high head pump are used.
For large breaks the low head (RHR) pumps and the accumulators provide the required f
ECCS flow.
l In the event of a small LOCA, resulting in a pressure between 1200 and 600 psig, and the worst single failure (Bus 149 which powers the operable centii-fugal charging pump), only 2 SI pumps and no charging pumps would be available.
i' This would result in a reduction in ECCS flow of approximately 25%.
l 8211010012 820924 PDR ADOCK 05000295 P
. Evaluation Consnonwealth Edison has provided information from Westinghouse sensitivity studies which indicate that reduction in ECCS flow would result in less than a 250 F increase in Peak Clad Temperature (PCT) assuming operating at full power. Since the FSAR small break LOCA analysis indicates a PCT of 1747'F, the 250 F increase would result in a PCT of 1997'F which is below the 10 CFR 50.46 limit of 2200*F and the administrative limit of 2050*F.
There are three additional considerations favoring the approval of the requested change. These are:
(1) the licensee has indicated that more recent Westinghouse ECCS evaluation models would demonstrate additional margin to the PCT criteria, (2) the request is for operation without the centrifugal charging pump for only l
three additional days, and (3) additional measures are being taken to increase the reliability of the remainder of the ECCS.
Based on the information provided by the licensee we conclude that operation in the proposed manner would not result in exceeding the Commission regulation I
(10 CFR 50.46) in the event of a LOCA with a single failure. We, therefore, find the proposed change acceptable and conclude that it would not result in an undue risk to the health and safety of the public.
I Environmental Consideration We have determined that the 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 the amendment involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 551.5(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.
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Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated, does not create the possibility of an accident of a type different from any evaluated previously, and does not involve a significant reduction in a margin of safety, 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 Commission'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.
Date:
September 24, 1982 Principal Contributors:
D. Wigginton G. Holahan
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