ML19331C033
| ML19331C033 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 08/01/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19331C030 | List: |
| References | |
| NUDOCS 8008140069 | |
| Download: ML19331C033 (3) | |
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UNITED STATES 8
NUCLEAR REGULATORY COMMISSION o
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION AMENDMENT NO. 72 TO LICENSE NO. DPR-44 AND AMENDMENT NO. 70 T0 LICENSE N0. DPR-56 PEACH BOTTOM ATOMIC POWER STATION UNITS 2 AND 3 PHILADELPHIA ELECTRIC COMPANY 00CKET NOS. 50-277 AND 50-278 Introduction In its letter dated August 1,1978, the Philadelphia Electric Conpany (PECo) requested an amendment to the licenses for the Peach Bottom Atomic Power Station Units 2 and 3 to increase the maximum suppression pool temperature during normal plant operation from 90 F to 95 F.
That request was made to allow for potentially high river water temperatures during the summer months which might result in suppression pool temper-atures in excess of Technical Specification limit.
Because of the recent heat wave over a large part of the continental United States, the suppression pool temperatures are nearing the existing Technical Specification limit.
Discussion l
The Technical Specifications for the Pc h Bottom plant require that:
(1) in the event that the suppression pool temperature exceeds 90 F during normal plant operation, the plant shall be in a cold shutdown l
condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />; (2) in the event that the suppression pool temperature exceeds 100 F during testing which adds heat to the pool, the pool temperature shall be reduced below 90 F in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or the l
plant shall be in a cold shutdown condition in the subsequent 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />; l
(3) in the event that the suppression pool tenperature reaches 110 F, the reactor shall be scrammed and power operation shall not be resumed f
until the pool temperature is reduced below 90 F; and (4) in the event that the suppression pool temperature reaches 120 F during reactor isolation conditions, the reactor shall be depressurized to less than 200 psig at normal cooldown rates. These requirements stem from the l
initial conditions assumed in the containnent response analyses for loss-of-coolant accident (LOCA) and safety-relief valve (SRV) discharge transients.
In its submittal, PECo requested that the 90 F limit be increased to 95 F and provided analyses of the design basis LOCA and SRV discharge events which consider the revised limit.
Evaluation With respect to LOCA transients, the principal considerations are (1) the containment design pressure and temperature, (2) the pressure and temper-ature envelope used for the environmental qualification of equipment 8008140Ch
located within the containnent, (3) the net positive suction head (NPSH) for the Energency Core Cooling System (ECCS) pumps, and (4) the nexinom suppression pool temperature for steam condensation.
To address these considerations, PECo submitted the original suppression chamber response analyses for Peach Bottom, which used the 90 F initial condition, and compared it to similar analyses for the Browns Ferry plant, which used d 9b'f limit.
Based on this comparison, PECo concluded that the resultant change is in the order of 5 F (with a corresponding pressure change of approximately 0.5 psi).
Both analyses were perforned using assumptions for containnent response analyses which are acceptable to the staff (Standard Review Plan, Section 6.2.1.1.C).
Further, we concur that these analyses are reasonably com-parable.
Based on the conparison presented, we conclude that the resultant cor,tainu;nt response for Peach Bottom with an initial pool temperature of 95*F will be well within the design values of 56 psig and 281*F and the change in the envelope used for environmental qualification will be insignificant.
With respect to NPSH, PECo submitted a comparison of the mininum required NPSH for the ECCS pumps with that obtained with the minimum containment pressure.
These analyses indicate that there is at least a two to three psi margin in the NPSH. These analyses hypothetically assumed a m'ximum pool temperature of 202 F in conjunction with a O psig centainment pressure, in accordance with the requirements of Regu'latory Guide 1.1, and are, therefore, acceptable.
The original design basis LOCA for the Peach Bottom plant was predicated on naintaining the pool temperature below 170 F to assure complete con-sideration of the steam evolving from the postulated break and the subsequent removal of heat from the containment via the suppression pool and the Residual Heat Removal (RHR) system. The 170*F limit was based on data from the Bodega Bay and Humboldt Bay test facilities which formed the original basis for the containment design, as described in the plant's Final Safety Analysis Report (FSAR).
The suppression pool temperature response in the licensee's submittal and the FSAR show a peak pool temperature of approximately 190 at 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> af ter the postulated acci-dent for mini'num cooling capability. Ilowever, steaming from the break ends much earlier in the transient (i.e., within minutes) and subsequent heat removal from the core to the pool is via subcooled ECCS water.
The pool temperature reached 170 F at approximately 1.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> for an initial pool temperature of 90 F and approxinately 15 minutes sooner for an initial pool temperature of 95"F, still well after steaming has stopped.
Further, recent tests in the Mark I Full Scale Test Facility (General Electric topical report NEDE-24539) have indicated condensation effective-ness at pool temperatures above 170 F.
Therefore, we conclude that the
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. proposed change will not adversely affect the condensation effectiveness or the heat removal capability of the containment system.
With regard to SRV discharge transients, the limiting event is a stuck-open valve.
In its submittal, PECo presented revised pool temperature transients for the SRV discharge events.
For the limiting event, the controlling parameter is the time of reactor scram.
Since the Technical Specification requirement for reactor scram at a pool tenperatsre of 110*F has not been changed, we conclude that the proposed char.ge will not significantly affect the SRV discharge transients.
Summary Based on the evaluation described above, we conclude that the proposed increase in the maxinum suppression pool temperature during normal plant operation from 90 F to 95 F will not adversely affect the containment design basis and is, therefore, acceptable.
Environmental Consideration We have determined that the amendments do 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 nede this determination, we have further concluded that the amendments involve an action which is insignificant from the standpoint of environnental inpact aand pursuant to CFR 51.5(d)(4), that an environmental inpact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of the amendments.
Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the anendnents do not involve a significant increase in the probability or consequences of accidents previously considered and d not involve a significant decrease in a safaty margin, the amendments not involve a significant hazards consideration, (2) there is reason-u'le assurance that the health and safety of the public v.ill not be
- t. idangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Connission's regulations and the issuance of the amendnents will not be inimical to the common defense and security or to the health and safety of the public.
Dated: August 1, 1980
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