ML20078R229
| ML20078R229 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 10/31/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20078R176 | List: |
| References | |
| TAC-48375, TAC-48376, TAC-483775, NUDOCS 8311140435 | |
| Download: ML20078R229 (3) | |
Text
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p UNITED STATES y.
NUCLEAR REGULATORY COMMISSION a-
- y WASHING TON, D. C. 20555 t
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT N0.78 TO FACILITY DPERATING LICENSE N0. DPR-24 AND AMENDMENT N0. 82 TO FACILITY OPERATING LICENSE NO. DPR-27 WISCONSIN ELECTRIC POWER COMPANY POINT BEACH NUCLEAR PLANT, UNIT NOS. 1 SAND 2 DOCKET NOS. 50-266 AND 50-301 INTRODUCTION By letter dated April 27,1982(Ref.3),asmodifiedMarch 23, 1983 (Ref. 1),
Wisconsin Electric Power Company (WEPC) requested a revision to the Point Beach Unit Nos.1 and 2 Technical Specifications (item 10 of Table 15.3.5-1) to change the undervoltage setpoint and the trip time delay of the loss of voltage relays. The proposed changes are in response to the ' staff's Safety Evaluation dated January 6, 1982 (Ref. 2) on the interim change request for the degraded voltage relay setpoints..
In Reference 2, the staff identified that the existing setpoints of the loss of voltage relays would not adequately protect the Class 1E equipment from grid undervoltage during the time delay of degraded voltage relays. Sub-sequently, in a letter dated April 27, 1082 (Ref. 3), the licensee identified that they had misinterpreted the characteristic curves of the loss of voltage and load shedding relays and submitted an application to amend the Technical Specifications. The time delays for 0 volts and also 90% of the voltage setpoints were changed for both sets of loss of voltage relays. Before the completion of the staff review of the proposed changes to the Technical Speci_fications, the licensee proposed to change the type and the setpoints of the loss of voltage relays per their letter dated June 1,1982 (Ref. 4).
This necessitated a revision to the proposed changes to the Technical Speci-fications which had been submitted by the licensee in Reference 1.
EVALUATION The present Technical Specifications list 2450 volts 3% (min. 57% of 4160) as the setpoint for the 4.16 kV loss of voltage relays. The associated time delay is 0.3 seconds for 0 volts and 1.2 second for 90% of the voltage setting with a 5% drift. Since the one minute rating of all Class 1E motors is 75% terminal voltage (approximately 72% of respective bus voltage),
and the time delay of degraded voltage trip setpoint is a maximum of 60 seconds, the equipment is not adequately protected against undervoltage in the bus voltage range between 57% and 72% of 4160 volts for about one' minute. This has been discussed in detail in Reference 2.
Also, since the existing loss 8311140435 031031 PDR ADOCK 05000266 P
.. of voltage relays are induction disc type with inverse time undervoltage characteristics, they cannot be set to a voltage / time curve that would provide tr,ip above 72% of bus ~ voltage and still permit starting large motors with the minimum calculated 4160 volt _ bus voltage (Ref. 4). The licensee has, therefore, selected a definite trip time, solid state relay-(ITE-270) which is capable of achieving both the above requirements. The Technical Specification change
.(Reference-1) proposes the loss of voltage relay setpoint to be 3220 volts
.2% (min. 3220 - 64 = 76% of 4160 volts) with a maximum time delay of 1 sec.
i 10% from 0-to 100% of-voltage ~ setting. The proposed voltage setpoint will protect Class IE equipment from any undervoltage below its one minute rating with a 4% safety margin and pr: event spurious trips when starting large motors.
.The revised. time delay tolerance of both the 4.16 kV and 480 V loss of voltage
. relays is based on the correct interpretation of the voltage / time characteristic curves as identified by the licensee in Reference 3.
Therefore, the relays will be accurately calibrated for the correct tolerance and spurious trips will not result.
Based on the above evaluation, the staff finds that the proposed changes to the. Technical Specifications (item 10 of Table 15.3.5-1) will" ensure adequate protection of Class IE equipment from grid undervoltage conditions and are therefore' acceptable.
Environmental Consideration We have determined that the amendments do 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 amendments involve an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 651.5(d)(4), that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of the amendments.
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 the amendments will not be inimical to the common defense and. security or to the health and safety of the public.
Date:.0ctober 31, 1983 Principal Contributor:
T. Colburn I. Ahmed
/,..
- References 1.
WEPC Letter (C. W. Fay) to NRC.(H. R. Denton) dated March 23, 1983.
2.
NRC Letter (T. G. Colburn) to WEPC (Sol Burstein) dated January 6,1982.
3.
WEPC Letter-(C. W. Fay) to NRC (H. R.-Denton) dated April 27 1982.
- 4. 'WEPC Letter (C. W. Fay) to NRC (H. R. Denton) dated June.1 1982.