ML20248C928
| ML20248C928 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 05/29/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20248C923 | List: |
| References | |
| NUDOCS 9806020278 | |
| Download: ML20248C928 (2) | |
Text
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.gk UNifED STATES g
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NUCLEAR REGU.LATORY COMMISSION 2
WASHINGTON, D.C. 20066-0001 f
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.198 TO FACILITY OPERATING LICENSE NO. DPR-71 AND AMENDMENT NO. ??8 TO FACILITY OPERATING LICENSE NO. DPR-62 CAROLINA POWER & LIGHT COMPANY BRUNSWlCK STEAM ELECTRIC PLANT. UNITS 1 AND 2 DOCKET NOS. 50-325 AND 50-324 1.0 INTROD_UCTION By "BSEP-95-0561, Application for Amends to Licenses DPR-62 & DPR-71,modifying RPS Electrical Protective Assemblies Channel Functional Test Surveillance Interval in TS [[SR" contains a listed "[" character as part of the property label and has therefore been classified as invalid.,per GL 91-09|letter dated November 15,1995]], Carolina Power and Light (CP&L) proposed a revision to the Technical Specifr:ations (TS) for Brunswick Steam Electric Plant (BSEP), Unit Nos.1 and 2.
The revision pertains to modification, of the channel functional test interval for the Electrical Protective Assemblies (EPAs) in the Reactor Protection System (RPS). This proposed change is a TS line item improvement per guidance in Generic Letter (GL) 91-09, " Modification of Surveillance Interval for the Electrical Protective Assemb'ies in Power Supplies for the Reactor Protection System." The proposed TS change includes TS 4.8.2.5 and asociated TS Bases.
When performing an EPA surveillance test at power operation, a half scram is expected by design. The half scram is obtained from power interruption while performing a " dead bus transfer" of the RPS bus to the alternate power supply. In the past, licensees have experienced problems resetting the half scram, resulting in inadvertent scrams and group isolations. This result challenges safety systems and eventually could cause system degradation. By the proposed change, EPA testing will be performed with the unit in cold shutdown, thereby reducing the possibility of inadvertent trips and challenges to safety systems. Also, the licensee reported by phone on October 14,1997, that the logic cards were upgraded during February 1997 with third generation logic cards with low set point drift, which can support the change in surveillance interva! irom every six months to every cold shut down.
2.0 EVALUATION Redundant EPAs are provided to monitor the output of each RPS motor-generator (MG) set power source. Breakers located between the MG sets and the RPS are tripped upon sensing an abnormal MG set output voltage or frequency. This protects the RF'S from the effsets of continuous operation with a degraded power source. Because the RPS is not qualified for operation under degraded power source conditions, the EPAs preclude the potential for RPS l
system failures or failure of other safety actions due to abnormal MG set electrical output conditions.
The EPA channel functional test requires the licensee to transfer power for the RPS from the associated MG sat to the alternate power supply. Because the transfer of RPS power involves a " dead-bus transfer," power is momentarily interrupted, which causes a half scram or group isolations. As an altemative, the licensee couM perform tests without a bus transfer, but this 9006020278 990529 PDR ADOCK 05000324 P
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2 procedure also results in a momentary interruption of power to the RPS when each EPA channel is tripped during the channel functional test. At many boiling-water reactor (BWR) plants, licensees have encountered problems with the reset of the half-trip resulting in inadvertent scrams and group isolations that challenge safety systems.
The Niagra Mohawk Power Corporation provided an analysis for the Nine Mile Point Plant in a proposal submitted on December 15,1988, that calculated the safety risks and benefits of the TS change to the RPS EPA surveillance interval. Also during the review of a similar TS change for Dresden Nuclear Power Station, the staff concluded that this TS change applies generically for BWRs as line item TS improvement. This conclusion formed the basis for the staff's issuance of Generic Letter (GL) 91-09 to provide the guidance for increasing the surveillance interval for EPA testing. Based on this guidance, the licensee proposed that the test interval for the EPAs be changed from every 6 months to each time the p! ant is in cold shutdown for a period of more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> unless performed in the previous 6 months. Also, the latest revision of the BWR standard Techn; cal Specifications (STS) requires EPA ter.ing in accordance with the guidance in GL 91-09. Therefore, the staff finds the licensee's propored change to TS 4.8.2.5 acceptable as it is consistent with the previous staff approval.
The licensee also proposed corresponding changes to the TS Bases that would reflect the change to TS 4.8.2.5. The staff finds these changes acceptable.
Based upon a review of the licensee's submittal, the staff concludes that the proposed change to the BSEP Units 1 and 2 TS for EPA surveillance testing is consistent with the BWR STS and GL 91-09 guidance and as such will reduce the likelihood of inadvertent trips and challenges to safety systems. Therefore, the change to the TS and associated Bases is acceptable.
3.0 STATE CONSULTATION
in accordance with the Commission's regulations, the State of North Carolina official was notified of the proposed issuance of the amendments. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a surveillance requirement. The NRC 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 proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (61 FR 34887). 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 or environmental assessment need be prepared in connection with the issuance of the amendments.
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endarigered by operation in the proposed manner, (2) such activities will be conducted la com'pliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor. S. Salicrup Date:
May 29,1998