ML20052D549
| ML20052D549 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 04/12/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20052D547 | List: |
| References | |
| NUDOCS 8205060577 | |
| Download: ML20052D549 (2) | |
Text
UNITED STATES g
"g NUCLEAR REGULATORY COMMISSION r,,
WAStlifJGTOfJ, D. C. 20555
%,l..... }y y SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 44 TO FACILITY OPERATING LICENSE NO. NPF-3 THE TOLEDO EDIS0N COMPANY THE CLEVELAND ELECTRIC ILLUMINATING COMPANY DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO. 1 DOCKET N0. 50-346 Introduction By letter dated March 23, 1979, the Toledo Edison Company (TECo) proposed several amendments to the Davis-Besse Unit No.1 operating license. One of these proposed amendments would allow a modification of the containment isolation signals for th reactor coolant pump (RCP) seal injection and return lines and for the reactor coolant system (RCS) makeup line.
Discussion A loss of offsite power at Davis-Besse will cause tripping of the reactor, main turbine, and all RCPs. Code safety valves will open to relieve high pressure in the steam generator caused by the load rejection, and auxiliary feedwater flow will be initiated immediately upon loss of the RCPs. TECo states that these events can cause an RCS cooldown and depressurization sufficient to actuate High Pressure Injection (actuates at pressures less than 1620 psig). This low RCS pressure signal also serves to isolate containment, which includes isolation of the RCP seal injection and return lines and the RCS makeup line. However, TECo states that isolation of seal cooling at RCS pressures greater than 450 psig may damage the seals and subsequently cause their failure. TECo also states that the cooldown following a loss of offsite power can lead to pre'ssurizsr level dropping sufficiently to uncover the heaters. TEco is proposing that the isolation signal for these lines be changed from 1620 psig to 420 psig RCS pressure. This will assure continued RCP seal cooling on a loss of offsite power and help control RCS volume so that adequate pressurizer level is maintained.
Evaluation The effect upon the RCP seals due to loss of seal cooling has been described by TECo in a letter dated December 28, 1979. On the basis of our preliminary review of this infomation, we consider that isolation of seal cooling for Davis-Besse on a loss of offsite power is undesirable since seal damage could result causing primary coolant leakage into containment equivalent to a small break loss of coolant accident. We also consider that loss of makeup flow due to system isolation on a loss of offsite power is undesirable 8205060577 820412 PDR ADOCK 05000346 P
since loss of pressurizer level indication could result.
Pressurizer level should remain within the indicating band during anticipated transients to assure that the operators are provided with complete information to guide their actions.
We find that changing the isolation signal for the RCP. seal injection and return lines from 1620 psig to 420 psig is acceptable since this would help assure RCP operability over a wider range of plant conditions.
We also find that the change in the makeup line isolation signal is acceptable since this will help in maintaining pressurizer level within the indicating range. Diversity in isolation signals is maintained with this modification since the high reactor building pressure (4 psig) isolation signal is retained. Thus, protection from fission product release through these lines during a loss of coolant accident will be adequately provided by this diversity.
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 the amendment.
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 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 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:
April 12, 1982 l
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