ML20079M118
| ML20079M118 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 12/29/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20079M099 | List: |
| References | |
| NUDOCS 8401270186 | |
| Download: ML20079M118 (2) | |
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g UNITED STATES
!4 NUCLEAR REGULATORY COMMISSION
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 73 TO FACILITY LICENSE NO. DPR-35 BOSTON EDIS0N COMPANY PILGRIM NUCLEAR POWER STATION DOCKET N0. 50-293 1.0 Introduction By letter dated April 5, 1983, Boston Edison Company (licensee) reauested that the liniting safety system setting of Technical Specification Item 2.2.8 of Appendix A be changed from "1095 psig 11 psig" to " Normal set-point will be selected between 1095 and 1115 prig.
All valves shall be set at this nominal setpoint 11 psi."
This change would allow an increase of the safety / relief valve (SRV) setpoint by 20 psi and a return to normal operating dome pressure in the next cycle, while still increasing the simmer margin by 10 psi over its present value. Operating data demonstrates that an increase in the valve simmer margin (difference between normal plant operating pressure and the SRV setpoint) will reduce the probability of pilot valve leakage.
II. Evaluation The licensee provided a study performed by the General Electric Company (GE) to evaluate the safety effects of raising the SRV setpointsmby 30 psi (10 psi more than requested here). The safety analysis for Pilgrim Cycle 6 was used for determining which transients are limiting. The increase in SRV setpoint affects only those events which result in valve actuation to limit the system pressure. The generator load rejection with bypass failure is the most severe reactor isolation event. The results of the GE analysis based on an increase of 30 psi indicated that the peak pressure would be within 110% of the system design pressure and that the operating MCPR limits established are acceptable with the new setpoints.
A design basis LOCA (large break LOCA) would cause system pressure decay during the accident, and the increse in SRV setpoint would have no effect on the results. However, for small breaks, the reactor would remain pressurized until initiation of the automatic depressurization systerr and the increase in SRV setpoint wnuld result in a slight increase it inventory loss through the break.
The results of the small break L0tA' analysis showed a 7 F increase in ocak clad temperature (PCT) from 1875 F to 1882 F due to the increase of 30 psi in SRV setpoint.
This PCT is still well below the 2200 F PCT limit established by 10 CFR 50.46(b)(1) and is, therefore, acceptable.
8401270186 031229 ER ADOCK 05000293 PDR
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General Electric also evaluated the effects of a 30 psi increase in SRV setpoint on the RCIC and HPCI systems and determined that they would be capable of providing adequate flow with the higher setpoint, i
We have reviewed the licensee's submittal and find that the results of l
the GE study are appropriate for a 30 psi increase in SRV setpoint and would not constitute a significant decrease in safety margin. The reouested i
increase o# 20 psi would have less effect on the PCT than a 30 psi increase.
Therefore, we conclude that the proposed amendnent is acceptable.
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III.
Environmental 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 actinn which is 1
insignificant from the standpoint of ' environmental impact and, pursuant to j
10 CFR 551.5(d)(4), that an environmental impact statement, or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
j IV. Conclusion We have 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, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendnent will not be inimical to the common defense and security or to the health and safety of the public.
I Principal Contributor:
C. Liang Dated:
December 29, 1983 i
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