ML20070G501
| ML20070G501 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 03/06/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20070G497 | List: |
| References | |
| NUDOCS 9103120125 | |
| Download: ML20070G501 (3) | |
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UNITED STATES e
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SAFETY _ EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0.150 TO PROVISIONAL OPERATING LICENSE NO. DPR-16 GPU NUCLEAR CORPORATION AND JERSEY R RTRAL POWER &_ LIGHT COMPANY OYSTER CREEK NUCLEAR GENERATING STATION DOCKET NO. 50-219
1.0 INTRODUCTION
By letter dated December 18, 1989, GPU Nuclear Corporation (GPUN/the licensee) requested changes to the Oyster Creek Technical Specifications (TS).
GPUN submitted additional information by letters dated April 30, October 16 and November 16, 1990. The proposed TS will permit removal of seven main steam safety valves (SVs). The current electromatic relief valves (EMRVs) plant configuration includes 16 SVs and 5 The original design for Oyster Creek overpressure protection was based on ASME Section I,1962 Edition.
The ASME Section.I deals specifically with power boilers and not nuclear reactors.
(In 1962, there was no ASME Section III which deals with nuclear reactors.) This edition was interpreted to require that the safety valve capacity be such that all potentially-generated steam by the boiler (reactor vessel) be discharged without credit for fuel stoppage. 'The current versions of the ASME code allow (Sections I and III) credit for operating or safety controls in the boiler or nuclear reactor. GPUN proposes to take credit for the high flux scram and plans to remove 7 out of 16 safety valves provided at Oyster Creek.
The licenst.e wishes to remove the valves to 1) reduce worker radiation exposure associated with valve maintenance; 2) reduce the likelihood of inadvertent valve opening or leakage; and 3) to reduce maintenance costs.
2.0 EVALUATION At Oyster Creek, there are two emergency isolation condensers which are started-automatically on reactor high pressure. There are five electromatic relief valves (EMRVs). The turbine bypass capability-is 40%.
In addition to the above, there are 16 safety vajves provided. The combined relief and safety valve capacity is about 13x10 #/hr which is approximately 180% of the tutal i
steam flot. The probability of lifting SVs is low due to the availability of l
the isolation condensers and the five EMRVs. The EMRVs discharge to the torus 1
(suppression pool) and the SVs discharge to the drywell.
9103120125 910306 ADCCK0500tjj9 g
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- GPUN performed an overpressure protection analyses to verify that nine SVs are sufficient to meet the acceptance criteria for overpressure, protection.
The impact on ATWS response was also examined.
1 2.1-Overpressure protection-Main Steac Isolation Valve (MSIV) Closure With High Flux Scram, No Recirculation Pump Trip (RPT) (Nine SVs And No RPT)
The RETRAN-02 Mod 4 code was used for this analysis. GPUN has based the analysis on the initiation of a reactor scram by the high-neutron flux signal which is the second safety grade scram signal from the reactor protection system following MSIV closure.
It was assumed that the position switches of the MSIVs failed to scram the reactor. The analysis took credit for only nine SVs.
No credit was giver, to the five ENRVs, the RPT, or the isolation con-densers.
The results of these analyses demonstrate that the maximum p(ressure will remain below the 1375 psig limit.
For the inost severe transient closure of all MSIVs with a high neutron flux scram at PO%), the maximum vessel pressure is 1361 psig when only nine SVs are assumed to operate in the safety mode.
Since the calculated peak pressure 1361 psig is within the acceptance criterion of 1375 psig, the overpressure protection analysis is acceptable.
2.2 Anticipated Transient Without Scram (ATWS)-MSIV Closure ATWS (8 Safety Valves) With RPT A MSIV closure ATWS event with RPT was evaluated to assess the effect of removal of safety valves on transient response. The transient was analyzed with eight safety valves, five EMRVs and with RPT. The peak calculated pressure was 1282 psig which is well within the ASME service level C over-pressure limit (1500 psig) typically used as a guideline for ATWS analyses.
Since there are only nine safety valves instead of 16, the peak reactor pressure during the transient is increased. This increased pressure will cause a slight increase _in the amount of steam discharged to the pool initially through the EMRVs. The additional heet input is small because it is due primarily to the higher initial pressure spike. With the pool cooling system in operation (as procedures require during an ATWS) the containment pressure and temperature parameters are not expected to change significantly relative j
to the previous plant configuration.
GPUN performed overpressurization analyses consistent with SRP 5.2.2 to support its proposal to removal seven safety valves at Oyster Creek. The results were E
consistent with the NRC staff's acceptance criteria that pressure not exceed L
110% of design. The licensee also discussed the impact on ATWS response indicating no significant impacts. The GPUN proposal to remove seven safety valves from the current 16 safety valves is therefore acceptable. The changes proposed in Technical Specifications 2.3.F and 4.3 E reducing the number of safety valves and the bases are also acceptable.
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3.0 ENVIRONMENTAL CONSIDERATION
Pursuant to 10 CFR 51.21, 51.32 and 51.35, an environmental assessment and finding of no significant impact have been prepared and published in the Federal Register on February 26, 1991 (56 FR 7883). Accordingly, based upon the environmental assessment, we have determined that the issuance of the amendment will not have a significant effect on the quality of the l
human environment.
4.0 CONCLUSION
The staff has concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the will not-be endangered by operation in the proposed manner, and (2) public such activitics will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security nor to the health and safety of the public.
Principal Contributor:
G. Thomas Dated:
March 6, 1991 l
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