ML20210R256
| ML20210R256 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 08/26/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20210R248 | List: |
| References | |
| NUDOCS 9709020360 | |
| Download: ML20210R256 (3) | |
Text
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RAFETY EVALUATION BY THE OFFICE OF NUCI FAR REACTOR REGULATION
, RFLATED TO AMEN _NENT NO. 98TO FACILITY OPERATING LICENRF MPF 88 AND AucNmFNT NO. 76 TO FACILITY OPERATING LICENRK NPF-81 SOUTHERN NUCI FAR OPERATING COMPANY. INC.. ET AL.
VOGTLE Fl FCTRIC GENERATING PLANT. UNITS 1 AND 2 DOCKET NOS. 50-424 AND 50-425
1.0 INTRODUCTION
By letter dated June 13,1997, as supplemented by letter dated July 18,- 1997, Southem Nuclear Operating Company lInc., et al. (the licensee) proposed license amendments to change the Technical Specifications (TS) for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2. The proposal would change the presswiser safety valve (PSV) setpoint range in TS 3.4,10 from 2460 2510 psig to 2410 2510 poig. The TS Bases clarify that the current setpoint range is based on a nominal setpoint of 2485 psig with a tolerance of *1%. The proposed setpoint would be based on a nominal setpoint of 2460 psig (1% lower than the current setpoint) with a tolerance of *2%..The supplemental material did not change the no signifmant hazards finding or expand the scope of the original Federal Ba91 stet notice.
2.0 EVALUATION The proposed TS will lower the nominal setpoint of the PSV by 1% and increase the PSV setpoint tolerance by 1%. Therefore, the proposed changes will keep the upper limit of the PSV setting of 2510 pelg unchanged. However, the allowable lower limit will be reduced by 2%._ As a result,' the safety analyses conoeming peak reactor coolant system (RCS) pressure will not be affected. Only those transients for which it is conservative to minimize the RCS pressure are potentially impacted by the proposed changes.
The licensee has performed an evaluation of the effects of the proposed changes on the Vogtle
- safety analyses. This evaluation concluded that: (1) the proposed change of PSV settings has no effect on the analyses of Loss of Coolant Accident (LOCA) and Steam Generator Tube Rupture events since the PSVs are not modeled in these analyse 4 and (2) for transients for
' which it is conservative to minimize the RCS pressure; the pressurizer. Power Operated Relief Valves (PORVs) are assumed to automatically lift to maintain the RCS pressure below the revised minimum PSV opening setpoint of 2410 psig, and (3) the results of a reanalysis of the inadvertent operation of the Emergency Core Cooling System (ECCS) during power operation support an increase in the negative tolerance to -2% with' respect to the reduced nominal Nb24 D
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2-setpoint pressure of 2460 psig ( 3% with respect to the current nominal setpoint pressure of 2485 psig). This analyzed scenario represents a bounding case for evaluating the consequences for a lower PSV set point since the PORV setpoint is lower than the revised minimum PSV opening setpoint, The licensee has re analyzed the inadvertent operation of the ECCS based on the use of emergency operating procedures (EOPs) to make PORVs available by manually opening their associated block valves within 10 minutes of entering into the transient. This assumption has been validated by simulator test results which indicate that the operators have been successful in accomplishing this procedure in substantially less than 10 minutes. The Vogtle operators are trained in the use of these EOPs.
The Vogtle PORVs are designed to safety grade standards. The power supplies and instrumentation are Class 1E. To further assure the operability of the PORV for mitigating this event (inadvertent operation of the ECCS), the licensee has evaluated the equipment qualification test for the Vogtle PORVs to ascertain the cyclic performance rating. The qualification test included 1000 cycles at a rate of 20 cycles per minute. The results of the test enveloped the potential cycling predicted for the PORVs during this event. Therefore, The licensee concluded that the PORVs at Vogtle should be able to perform their function during the postulated inadvertent operation of the ECCS event without damage. The licensee also stated that the results of the reanalysis of the inadvertent operation of the ECCS event assuming 10 minutes time delay of the PORV opening indicated that there will be some water relief in liquid form through the PSVs during the event. Since the PSVs are generally designed for steam release, and under certain postulated conditions liquid relief may occur with the potential for causing damage to the valves, the staff evaluated the potential operating conditions of the PORVs and PSVs during the event (including the number of operating cycles for the PORVs and water relief through the PSVs).
Based on its evaluation, the staff finds that the PORVs and PSVs at Vogtle will be able to adequately perform their safety function during this event. The staffs basis for this assessment is that valves representative of those installed at Vogtle were tested in a program sponsored by the Electric Power Research Institute (EPRI) and documented in EPRI report number NP4628-SR, dated December 1982. The test was performed under full scale, full-flow test conditions which bound the expected operating conditions at Vogtle. These tests demonstrated the ability of the Vogtle PSVs and PORVs to perform their safety function of opening and closing for mitigating an inadvertent opera icn of ECCS event. Therefore, the proposed change modifying the PSV setpoint range from 2460-2510 psig to 2410 2510 psig in TS 3.4,10 is acceptable,
3.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Georgia State official was notified of the proposed issuance of the amendments. The State official had no comments.
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4.0 ENVIRONMENTAL CONSIDERATION
The amendments change requirements with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change
- in the types, of any effluent 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 (62 FR 38139_ dated July 16,1997).
Accordingly, the amendments meet the eligibility critsrla 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 cormection 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 endangered by operation in the proposed manner, (2) such activities will be conducted in compliance 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. C. Liang C. Hammer Date: August 26, 1997
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