ML20055A075
| ML20055A075 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 07/12/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20055A071 | List: |
| References | |
| NUDOCS 8207150453 | |
| Download: ML20055A075 (3) | |
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UNITED STATES f
s.,
h NUCLEAR REGULATORY COMMISSION
'y WASHINGTON, D. C. 20555
\\*****/SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR OYSTER CREEK NUCLEAR GENERATING STATION SUPPORTING AMENDMENT NO. 62 TO PROVISIONAL OPERATING LICENSE NO. DPR-16 GPU NUCLEAR CORPORATION AND JERSEY CENTRAL POWER & LIGHT COMPANY DOCKET NO. 50-219
1.0 INTRODUCTION
By letter dated August 27, 1981 GPU Nuclear Corporation and Jersey Central Power & Light Company (the licensees) requested an amendment to Provisional Operating License No.
DPR-16 for the Oyster Creek Nuclear Generating Station.
This amendment would authorize changes to the limiting set points for five electromatic relief valves for the Reactor Coolant System.
2.0 DISCUSSION AND EVALUATION Current Oyster Creek Technical Specifications (T/S) require the electromagnetic relief valve (ERV) opening setpoints to be less than or equal to 1085 psia.
A previous study to evaluate the structural response of the torus to the vent clearing effects during ERV discharge recommended lowering the opening setpoint of one ERV in each of two discharge lines to 1065 psia. This limited the number of initial valve lifts into a common discharge header to one valve, thus clearing the non-condensible gases from the pipe at a slower rate which reduces stresses on the torus. The remaining ERV's in each header would discharge into a pipe in which steam is flowing and would therefore cause lower stresses. Based upon the maximum pressurization rate which occurs during the limiting transient, a 20 psi margin was required between the two ERV opening septoints to ensure sufficient time difference between ERV openings to clear non-condensibles from the discharge pipe during blowdown.
A requirement from the TMI-2 lessons learned was to investigate methods to reduce the number of challenges to relief valves. One method to reduce relief valve challenges is to increase the opening setpoints. The licensee performed an analyses to determine if the Oyster Creek ERV opening setpoint could be raised to provide margin (operating pressure to opening setpoint pressure) similar to that which existed prior to lowering the setpoints on two of the ERV's; and in addition maintain a 20 psi opening s'etpoint separation to reduce torus stresses. The results show that the two lower opening setpoints could be increased from 1065 psia to 1085 psia and also that the three higher opening setpoints could be increased to 1105 psia.
8207150453 820712 PDR ADOCK 05000219 P
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Pressurization transients which result in relief valve actuation were reanalyzed with the revised setpoints and evaluated against the design criteria specified in the Technical Specifications. The design criteria used.for accepting the results of a pressurization transient are: (1) a peak pressure of less than the lowest safety valve (SV) setp61nt'for normal transients and 110% of reactor coolant pressure boundary design pressure for the limiting abnormal operational transient; and (2) a change in critical power ratio (ACPR) of less than 0.15, the ACPR for the previously calculated limiting transient (rod withdrawal error) for Oyster Creek.
The following pressurization transients were analyzed by the licensee:
turbine trip, main steamline isolation valve closure, loss of electrical load, loss of auxiliary power and loss of main condenser vacuum. The limiting pressurization transients are turbine trip and main steamline isolation valve closure. For the turbine trip transient the peak pressure was 1120 psia. The peak pressure for the main steamline isolation valve closure transient was 1135 psia.
Both the peak pressures from these transients are below the safety valve opening setpoint. The ACPR did not change for these transients.
The limiting abnormal pressurization transient is the turbine trip without bypass.
The resultant peak pressure was 1201 psia with a ACPR of.025.
The results of the transient analysis are acceptable since the design criteria speciffe'd above are not exceeded.
The limiting LOCA analysis for Oyster Creek is a large break which does not result in ERV actuation. Therefore, and ERV opening setpoint change has no effect on a large LOCA.
The limiting break size that results in ERV actuation is 1.0 sq. ft.
The increased ERV opening setpoints increases the calculated peak cladding temperature about 3 F.
The licensee states that this will not change the limiting break size or location nor result in ex-ceeding the 2200 F limit for clad temperature. We therefore, find the ERV opening setpoint increase effect on LOCA transients acceptable.
The licensee also performed an analysis to evaluate the affect of the pro-l posed ERV opening setpoint change on the hydrodynamic load along the header relief valve discharge pipes. The results show that the maximum hydro-dynamic load increased by 0.81% during the blowdown transient. This small increase will have a negligible impact on the torus structure, and is less than the original design with all ERV's opening at the same setpoint.
The overpressure analysis to determine compliance with the ASME Code (110%
of design pressure) is not affected by this ERV setpoint change. As discussed in the FSAR, the overpressure analyses takes no credit for reactor scram or ERV opening in verifying the design adequacy of the safety valves.
I Based on our evaluation, we conclude that the proposed changes to the technical specification, Section 2.2, Safety Limit-Reactor Coolant System Pressure are acceptable.
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3.0 ENVIRONMENTAL CONSIDERATION
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 impact. Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR ft.51.5(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.
4.0 CONCLUSION
We also conclude, based on the considerations discussed above, that:
(1) because the amendment does not involve a significant increase in the probability or consequences of accidents previously considered, does not involve a significant decrease in a safety margin, and does not create the possibility of an accident of a type different from i
any. evaluated previously, the amendment does not involve a significant hazards consideration; (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner; and (3) such activities will be conducted in compliance with'the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or the health and safety of the public.
5.0 ACKNOWLEDCMENTS The following NRC personnel contributed to this evaluation:
R. Frahm Date:
July 12, 1982
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