ML19249A020
| ML19249A020 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 07/26/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19249A015 | List: |
| References | |
| NUDOCS 7908170566 | |
| Download: ML19249A020 (3) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION W '/
c WASHINGTON. D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.10 TO FACILITY OPERATING LICENSE NO. NPF-5 GEORGIA POWER C0f9ANY OriLETHORPE ELECTRIC MEMBERSHIP CORPORATION ffJNICIPAL ELECTRIC ASSOCIATION OF GECRGIA CITYOFDALTON,GEORGd EDWIN I. HATCH NdCLEAR PLANT, UNIT NO. 2 DOCKET NO. 50-366 I ntroduction By letter dated July 23, 1979, Georgia Power Company (the licensee) proposed a change to t'he Technical Specifications appended to Operating License No.
NPF-5 for the Edwin I. Hatch Nuclear Plant Unit No. 2.
The change increases the Liniting Condition for Operation on Drywell Average Air Tenperature fren 135 F to 145 F.
The change was requested because the licensee has encounte ed difficulty in naintaining the volumetric average temperature belcw this lin t, particularly during the sunner season.
Evaluation The current Technical Specifications require that in Mode 1, 2 or 3 operation, the drywell average air temperature shall not exceed 135 F.
This value is one of the assuned initial conditions for evaluating the containment response to a LOCA to ensure that the structure's design limits are not exceeded. The licensee's analysis of the effect of the 10 F increase in drywell average air temperature would result in a short-tern post-LOCA containnent pressure increase of 1 psi or less.
We have reviewed the licensee's request as well as the initial analysis of containment response to a design basis accident as described in Section 6.2 of the Hatch Unit No. 2 FSAR. We have previously verified the analytical results of the 1icensee's model, (see NL' REG-0411), and determined that an input value of 135 F drywell air temperature yields a calculated peak drywell pressure of 57.5 psig.
Thus an input value of 145 F would yield a naxinum containnent pressure of <53.5 psig, which is still less than :.he ASME Code allowable pressure of 62 psig.
The licensee's subnittal also addressed the effect of local tenperatures on the environnental qualifications of safety related equipment which night be affected by the proposed 145'F linit.
His subnittal stated that he has established regional tenperature linits based on equipment qualifications.
In discussions with the licensee he indicated that these linits are lower than
- hose for which the ecuipnent is qualified for nomal operation.
7D 0817 0 S6 6 m 9 t, 295 Further, he stated that tenperature will be nonitored and naintained to assure a satisfactory long-tern environnent for components within the drywell.
We have reviewed the licensee's discussion of environmental qualification of equipnent as well as data on temperature profiles within the drywell, as discussed in the Staff's Safety Evaluation supporting Amendnent No. I to NPF-5.
Since the Technical Soecification on average drywell temperature is a volunetric average, the effect of a 10 F average increase on local temperatures within the drywell will not be linear.
Thus, local tenperatures nay increase on the order of 20-30 F at certain locations. The effect of increased terperatures over a long period of time would accelerate aging of safety related equipnent.
Since data on local temperatures is not available, we suggested to the licensee that the increased linit of 145 F average drywall air tenperature be pernitted only until the first refueling outage of Hatch Unit No. 2.
It is our judgenent that the effect of the increased temperature 1init until the first refueling outage would have negligible effect on aging, since the actual elevated tenperatures will occur only during seasons of expecially hot weather, i.e., only a few days per year. This tenporary change would thus pernit the licensee to continue operation of the facility while concurrently designing and performing appropriate nodifications to reduce the air tenperature in the drywell. He agreed.
In view of the foregoing we find the licensee's request as nodified by the staff to be acceptable.
The acceptability is based on the calculated peak containment pressure being within Code allowable and the insignificant effect of increased tenperature on aing of equipment during t he few days of es,ecially hot weather that will be experienced.
Environnental Considerations 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 inpact.
Having made this determination, we have further concluded that the amendment involves an acticn which is insignificant from the standpoint of environmental inpact and pursuant to 10 CFR Section Sl.5(d)(4) that an environmental inpact statenent or negative declaration and environnental impact appraisal need not be prepared in connection with the issuance of this anendnent.
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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 accidents previously considered and does not involve a significant decrease in a safety -:1rgin, 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 ininical to the ccomon defense and security or to the health and safety of the public.
Dated:
July 26, 1979 g
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