ML20029B390
| ML20029B390 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 03/04/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20029B389 | List: |
| References | |
| NUDOCS 9103070188 | |
| Download: ML20029B390 (3) | |
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O A, P,'I NUCLEAR REGULATORY COMMISSION UNITED STATES '
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SAFETY EVALUATION BY THE OFFICE OF WCLEAR REACTOR REGULAT_I_0)!
RELATED TO AMENDMENT NO.149 TO PROVISIONAL OPE! ~ 71G LICENSE NO. OPR-16 GPU NUCLEAR CORFORATION AND JERSEY CENTRAL 00MT5 LIGHT COMPANY OYSTER CREEK FJCLEAR GENERATING STATION 00cKFT NO.60-219
1.0 INTRODUCTION
Pursuant to 10 CFR 50.59, GPU Nuclear Corporation (GPUN, the licensee), operator of the Oyster Creek Nuclear Generating Station (OCNGS), submitted on July 10, 1990, aTechnicalSpecification(TS)ChangeRequestNo.188. This is a change request to Appendix A of the Provisional Operating License No. OPR-16. The change request proposes to reduce the low condenser vacuum reactor scram setpoint in Table 3.1.1 from 23 ir W s ug vacuum to 20 inches Hg vacuum and revises the bases to support the new setpoiot.
2.0 EVALUATION The low vacuum reactor scram provides protection to the condenser, turbine, and an anticipated loss of the reactor heat sink.
In the Final Safety Analysis Report (FSAR) Chapter 15, Section 15.2.5, there is a statement " A le-of condenser vacuum results in a loss of the main decay heat sink for the
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A turbine trip occurs at 22" Hg vacuum, and a reactor scram at 23" HG vacuum. This event behaves similarly to a turbine trip with bypass failure, since the bypass to the condenser is automatically blocked upon receiving the loss of vacuum at 10" Hg vacuum. Relief valves and the Isolation Condensers are used to remove decay heat. The loss of condenser vacuum is considered to be a transient of moderate frequency."
The TS Bases 3.1, page 3-1-4, has a statement, "A low condenser vacuum scram trip of 23" Hg has been provided to protect the main condenser in the event that vacuum is lost. A loss of condenser vacuum would cause the turbine stop valves to close, resulting in a turbine trip transient. The low condenser vacuum trip anticipates this transient and scrams the reactor. The condenser is capable of receiving bypans steam until 7" Hg vacuum thereby mitigating the transient and providing a margin." The TS 7" Hg vacuum bypass steam block does not agree with the 10" Hg vacuum stated in the FSAR.
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The licensee's pur?ose for changing the low vacuun reactor scram setpoint from equal or greater tian 23" Hg vacuum to 20" Hg vacuus is to reduce the high possibility of a spurious reactor scram when backwashing the condenser in the-sumer, when the condenser cooling water is at its highest temperature, while maintaining full load on the turbine, generator, and reactor.
The licensee.does not take credit for the low condenser vacuum reactor trip in the FSAR, Chapter 15, Section 15.2.5 analysis nor in any other transient analysis in the FSAR.
With the new setpoint of 20" Hg vacuum, the reactor scram will occur after the turbine trip of 22" Hg vacuum.
Since the turbine trip also scrams the reactor the low condenser vacuum reactor scram is now a backup to the turbine trip. The actual reactor scrorn would then occur at 22" Hg vacuum when the turbine trips, instead of the present condenser vacuum setpoint of 23" Hg.
The turbine trip without bypass bounds the loss of condenser vacuum trip.
- The licensee has performed an analysis using a computer code (RELAP5 H002) to evaluate several degraded condenser coolant and increased air 'eakage events and concluded that a setpoint~of 20" Hg condenser vacuum had little or no impact upon condenser protection as compared to 23" Hg vacuum.
Based on the above, the staff concludes that the change of the condenser low vacuum reactor trip setpoint from 23" Hg vacuum to 20" Hg vacuum is acceptable.
However, the value of steam bypass block in the FSAR of 10" Hg vacuum should be corrected to-agree with the value in the TS of 7" Hg vacuum.
3.0 ENVIRONMENTAL CONSIDERATION
-The amendment changes a requirement 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 amendment involves 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 signif-icant increase in' individual or cumulative occupational rediasion exposure.
The Comission has previously issued.a proposeu finding that the amendment
. involves no significant hazards consideration, and there has been no public c
coment on such finding. - Accordingly, the amendment meets 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 amendment.
4.0 CONCLUSION
The Comission has concluded, based on the considerations discussed above, that-(1) there is reasonable assurance that the health and safety of the public I
l c Eill not be endangered by operation-in the-proposed manner. (2) such activities will be conducted:in compliance with the Comission's regulations, and (3) the
_ issuance of-the amendment will not be inimical to the comon defense and security
-nor to the health and safety of the public.
Principal-_ Contributor:
F. Paulitz Dete:; March 4, ~ 1991 I
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