ML20033C290
| ML20033C290 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 11/16/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20033C284 | List: |
| References | |
| NUDOCS 8112021003 | |
| Download: ML20033C290 (2) | |
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UNI TED STATES NUCLEAR REGULATORY COMMISSION C
WASINGTON, D. C. 20555
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.8 g n -[f SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 77 TO FACILITY OPERATING LICENSE N0. UPR-33 AMENDMENT N0. 73 TO FACILITY OPEP.ATING LICENSE NO. DPR-52 TEN.1ESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-259 AND 50-260 1.0 Introduction By letter dated September 17,1931 (TVA BFNP TS 166) the Tennessee Valley Authority (the licensee or TVA) requested changes to the Technical Specifications (Appendix A) appended to Facility Operating License Nos. DPR-33 and DPR-52 for the Browns Ferry Nuclear Plant, Unit Nos.1 and 2.
The proposed amendments and revised Technical Specifications would modify the conditions under which start buses 1A and 1B must be operational.
2.0 Discussion On September 3, 1981, we issued Amendment Nos. 75 and 74 to Facility Licenses Nos. DPR-33 and DPR-52 to reflect the major modifications made to the auxiliary electrical systems for Browns Ferry Unit Nos.1 and 2.
The nodifications were made during the 6 month refueling-maintenance outage of Unit 1 and during the June 1981 shutdown of Unit 2.
Besides the significant improvements to the elec-trical system, the modif; cations resolved two generic issues - the adequacy of station electric distribution systen voltages and degraded grid protection for class lE power systems.
The Technical Specifications on the auxiliary electrical equipment approved by Amendment Nos. 75 and 72 were those submitted by TVA.
The requirements on start bus operability were the same as existed prior to the elec-trical modifications.
After the amendments were issued, TVA noted that these Technical Specifications would require shutting down both Units 1 end 2 within six hours upon the loss of one start bus.
TVA's cited justification is that present Technical Specification on the start buses is unnecessarily restrictive because, with the recently completed electrical modifications, start bus opera-bility is not related to using the 500 KV system (which is now the principal source of offsite power) or the 161 KV system (now a second backup source of off-site power).
3.0 Evaluation These changes primarily effect the availability of the start buses (l A,18) and relate these buses to their power supply (common station service transformers A & B).
The start buses are not safety related but under some plant lineups are used as a power supply to the shutdown buses which provide offsite power sources to the 4 KV shutdown boards (safety related).
The normal plant lineups would use the 500 KV unit station service transforners TUSS 1B and 28 through a KV unit board 1A, IB, 2A and 28 as the primary and alternate sources of power to 8112021003 011116 DR ADOCK 05000
, the shutdown buses.
Under these circumstances the start buses would serve as a third source of offsite power to the shutdown buses.
(This and other transfer schemes were provided by TVA in their April 9,1981 submittal.) Under plant lineups wherG both 500 KV sources of offsite power are not available the Technical Specifica-tions contain requirements to require either start bus operability or other means to insure that at a minimum at least two sources of offsite power are always available to shutdown buses 1 and 2.
These requested changes to Technical Speci-fications do not increase availability of offsite power to the class lE equip-ment but ctill provides at least two rources of offsite power to the shutdown buses under all operating conditions and meets the requirements of GDC 17.
The change in surveillance requirement 4.9.B(1) from inoperable to operable clariffes the 3.9.B(1) LC0 and covers the operability requirements if only one source of offsite power is available.
The proposed changes to the Technical Specifications are acceptable.
4.0 Environmental Considerations 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 made this detennination, we have further concluded that the amendments involve an action which is insignificant from the standpoint of en.vironmental impact and pursuant to 10 CFR 51.5(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 amendments.
5.0 Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the,Srobability or consequences of accidents previously considered and do not involve a significant decrease in a safety margin, the amendments do 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 Comission's regulations and the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated: November 16, 1981
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