ML20244D959
| ML20244D959 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 08/19/1988 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML20244D945 | List: |
| References | |
| GL-84-15, TAC-00092, TAC-00093, TAC-00094, TAC-92, TAC-93, TAC-94, NUDOCS 8904240224 | |
| Download: ML20244D959 (4) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF SPECIAL PROJECTS
- SUPPORTING AMENDMENT NO.153 TO FACILITY OPERATkNG LICENSE NO. DPR AMENDMENT NO.149 TO FACILITY OPERATING LICENSE NO. OPR-52 AMENDMENT NO.124 TO FACILITY OPERATING LICENSE NO. DPR-68 l
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TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT, UNITS 1, 2 AND 3 i
DOCKETS NOS. 50-259, 50-260 AND 50-296
1.0 INTRODUCTION
The staff has determined that the risk from station blackout is such that early actions to improve diesel generator reliability would have a significant safet By letter dated July 2, 1984 the NRC issued. Generic Letter
-(GL) y benefit.84-15 which contained proposed actions to improve and maintain diesel generator reliability.
GL 84-15 contained recommendations for changes to the Technical Specifications (TS) to reduce the number of fast starts and improve reliability.
By letter dated May.29, 1987, the Tennessee Valley Authority (TVA) (the licensee) submitted a TS change as recommended by GL 84-15 for the Browns
-Ferry Nuclear Plant (BFN) Units'1, 2 and 3.
Upon initial staff review it was apparent that the proposed amendments did not require the same level of testing as the. proposed TS in GL 84-15 when only one offsite power source is l.
operable and when one of any of the units' diesel generators, shutdown bus, j --
5-KY shutdown board or diesel auxiliary board are inoperable.
After discussions with tfie NRC staff, the licensee, by letter dated April 13, 1988, proposed additional TS changes which clarify the original application to better implement the recommendations of the generic letter.
2.0 EVALUATION The proposed changes to the BFN TS would prevent excessive testing and improve l
reliability of the diesel generators.
The proposed changes include the i
j following:
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. 1.
Delete the requirements for diesel generator testing whenever an emergency core cooling system (ECCS) train becomes inoperable.
TS 4.5.A.2, 4.5.B.3, 4.5.B.5, 4.5.B.6, 4.5.B.12, 4.5.C.2.b, 4.5.C.2.c, and 4.5.4.
2.
TS 4.9.B.1, 2, 3, 4, 5, and 6 require the remaining diesel generators and other electrical equipment to be tested "immediately and daily thereafter" whenever another diesel generator or other electrical equipment is inoperable.
These specifications would be changed to require testing within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and verify power availability for the associated or remaining boards within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter.
3.
Administrative chang'es to add Table 4.9.A which specifies diesel generator testing frequencies and reliability program. TS 4.9.A.1.a, Table 4.9.A, and 6.9.2.7.
4.
Restrict the requirement for diesel generator fast starts to once per 184 days. TS 4.9.A.1.a.
5.
Require a log book to record diesel generator starts.
TS 4.9.A.1.a.
The following pages would be revised only to provide proper pagination:
Units 1 and 2, pages 3.9/4.9-3, -18, -19, 21 and -22; Unit 3, pages 3.9/4.9-3, -17, -18, -19, -20, and -21.
The requirement to test the diesel generators whenever an ECCS train fails as stated in GL 84-15, will result in the excessive testing and degradation of the diesel engines.
Failures experienced in the ECCS and residual heat removal (RHR) service water systems have no mechanistic connection with the performance of operable diesel generators and therefore additional testing of the diesel generators is not required.
The current TS require the remaining diesel generators or other TS listed electrical equipment be tested "immediately and daily thereafter" whenever another TS listed power source is declared inoperable.
TVA has proposeo to nodify this requirement to require diesel testing within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and verification.of availability of power for the associated or remaining board (s) within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter.
The immediate testing currently required by the TS subjects the diesel engine to undue wear and stress on the engine parts. TVA states that a 24-hour interval will reduce unnecessary starting and stopping of equipment and eliminate cold fast diesel I
startups. TVA also states that the associated boards will be verified in terms of correct breaker alignment and indicated power availability from the control room.
The staff has evaluated these proposed changes and has determined that because no mechanistic relationship exists between the operability of an l
w
i individual power supply and the failure of other TS listed equipment, immediate testing is not necessary and, in fact, proper pre-lubrication before diesel startups should improve the reliability of the diesel generators. The proposed changes are also consistent with the frequency recommended in GL 84-15 and are, therefore, acceptable.
The proposed normal periodic surveillance testing frequency would be dependent upon test failure experience on a per diesel generator basis.
This change is consistent wfth GL.84-15 and does not relax the current regular testing fre-quency. The present surveillance interval is monthly and the longest interval allowed by the new requirement will be once per 31 days. The staff has deter-mined that the proposed surveillance frequencies will not adversely affect diesel generator performance, and is, therefore, acceptable.
The requirement for fa't start testing has been proposed to be limited to once per 184 days as recommended in GL 84-15.
Fast-start testing results in incremental degradation of the diesel engines and is therefore in opposition to diesel generator reliability and availability.
However, it is felt that fast-start tests should not be totally eliminated because of the need for such a capability during a design basis accident. The proposed change to cold fast diesel starting once per 184 days is, therefore, acceptable.
To provide additional diesel generator reliability the licensee has proposed changes to the TS to incorporate performance specifications which encompass aspects of the existing requirements for surveillance testing of diesel generators. stipulated in Regulatory Guide 1.108 and t..e qualitative recommendations of NUREG/CR-0660." The proposed changes are identical to the performance specifications recommended in GL 84-15 and are, therefore, accep-table.
The proposed changes to the TS are consistent with GL 84-15.
They provide positive improvements to diesel generator reliability.
Based on the above, the staff has concluded that the proposed changes to the TS will enhance plant safety, and are therefore, acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
The amendments involve a change to a requirement with respect to installation l
or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements.
The staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a
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- proposed finding that these amendments involve no significant hazards consider-ation and there has been no public comment on such findino. Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement nor environmental assessment need be prepared in connection with the issuance of these amendments.
4.0 CONCLUSION
The Commission made a proposed determination that the amendment involves no significant hazards consideration which was published in the Federal Register (52 FR 49232) on December 30, 19d7 and consulted with the State of Alabama.
No public comments were received and the State of Alabama did not have any comments.
The staff has conclud'ed, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's re-gulations, and (3) the issuance of the amendments will not be inimical to the common defense and security nor to the health and safety of the public.
Principal Contributor:
John Stang, T. Rotella Dated:
August 19, 1988
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