ML20004D970
| ML20004D970 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 06/01/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20004D968 | List: |
| References | |
| NUDOCS 8106100421 | |
| Download: ML20004D970 (4) | |
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UNITED STATES Ih)et[oj NUCLEAR REGULATORY COMMISSION i
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WASHINGTON. O. C. 20555 r-t a
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,d SAFETY EVALUATION D. C. COOK NUCLEAR PLANT, UNIT NOS.1 AND 2 DOCKET NOS. 50-315 AND 50-316 ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES INTRODUCTION AND
SUMMARY
Indiana and Michigan Electric Company (IMECo) was requested by NRC letter dated August 8,1979, to review the electric power system at D. C. Cook Nuclear Plant Units 1 and 2.
The review was to consist of:
(a) Determining analytically the capacity and capability of the offsite power system a.1d the onsita distribution system to autcutica'.ly start as well as operate all required safety loads within their required voltage ratings in the event of (1) an anticipated transient, or (2) an accident (such.as LOCA) without manual shedding of any electric. loads.
(b) Determining if there are any events or conditions which could result in the simultaneous or, consequential loss of both required circuits from the offsite network to the onsite electric distribution system and thus violating the requirements of GDC 17.
The August 8,1979 letter included staff guidelines for performing the required voitage analysis and the licensee was further required to perfomi a test in order to verify validity of the analytical results.
IMECo responded by letters dated December 17, 1979, May 28, 1980, and January 27, 1981. A detailed review and technical evaluation of the submittal was performed by EG&G under contract l
to NRC, and with general supervision by NRC staff. This work was reported in qlD(_,/OCtlN
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W EG&G's Technical Evaluation Report (TER), " Adequacy of Station Electric Distri -
bution System Voltages D. C. Cook Nuclear Plant Unit Nos. I and 2," dated April 1981 (attached). 'de have reviewed' these reports and concur in the conclusions that upon completion of the installation of the second level of undervoltage relays on 4ky buses A and 0 of units 1 and 2 and modification of the existing first level loss of voltage relays on the 4ky buses the offsite power system and onsite distribution system will be capable of providing acceptable voltages at the terminals of the Class lE equipment for worst case station electric load and grid voltages.
EVALUATION CRITERIA The criteria used by EG&G in this technical evaluation of the analysis includes GDC 5 (" Sharing of Structures, Systems, and Components"), GDC 13 ("Instrumenta.
tion and Control"), and GDC 17 (" Electric Power Sys'tems") of Appendix A to 10 CFR 50; IEEE Standard 308-1974 (" Class lE Power Systems for Nuclear Power Generating Stations"); ANSI C84.1-1977 (" Voltage Ratings for Elecjric Power Systems and Equipment - 60 HE"); and the staff positions and guidelines in the NRC letter to IMECo dated August 8, 1979.
ANALYSIS AND TEST FEATURES IMECo analyzed each offsite power source to the onsite distribution system under extremes of load and offsite voltage conditiens to determine the terninal voltages i
to the Class lE equipment. The worst case Class 1E equipment terminal voltages occur under the following conditions.
l l
. 1.
The maximum voltage occurs when the 69kV " alternate" source is at its maximum expected value (72.45kv) and supplying the minimum load.
2.
The minimum steady state voltage occurs when the 345 " preferred" source is at its minimum expected value (347kv) and supplying accident loads on one unit and shutdcwn loads on other unit.
3.
The worst case transient voltages occurs when the 345ky " preferred" source is at its minimum expected value (347kv) and supplying accident loads on one unit and shutdown loads on the other unit and the accident loads are.
bulk started.
It has been established that emergency 4ky loads would operate within allowable limits for the worst case conditions noted above.
IMECo has verified that the 69ky source does not have sufficient capacity to supply both safety trains on unit i and 2 concurrently and maintain voltages to equipment above 90%.
Technical Specification changes have been submitted that will administratively limit the loading on this power source to maintain at least 90% voltage under steady state conditions.
The voltage analysis was. verified by measuring, during a startup of unit 2, while unit 1 was at power, the voltage, current and phase angle reading of the preferred and alternate offsite station buses and the unit 2 auxiliary Suses. The comparison showed that the calculated voltages for the Class lE buses are within 2% of the measured bus voltages for unit 2.
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correlation verifies the adequacy of the analysis submitted. The results are applicable to Unit 1 based on similar loading conditions and onsite distribu-tion systems.
CONCLUSIONS We have reviewcl the EG&G Technical Evaluation Report and concur in the findings that:
1.
IMECo has provided verified voltage analyses to demonstrate that the Class lE equipment terminal voltages remain within acceptable operating. limits for the postulated worst case conditions.
2.
The tests to verify the analysis was valid and showed the analysis to be accurate.
3.
IMECo's reaffirmation of compliance with GDC 17 requirements is acceptable.
4.
The above conclusions are based on the completion"6'f the proposed codifica-tions for the first and second level undervoltage relays. GI&E should verify completion of the proposed modifications.
5.
The Technical Soccification changes proposed by IMECc will limit the loading on the 69kv alternate source of power to prevent undervaltage conditions on the Class lE distribution system.
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E G c G.n..-.
FORu EG&G494 (Eev 1179)
INTERIM REPORT Accession No.
Report No. EGG-EA-5339 Revision 1 Contract Program or Project
Title:
Selected Operating Reactors Issues Program (III)
Subject of this Document:
Adequacy of Station Electric Distribution System Voltages, D. C. Cook Nuclear Plant, Unit Nos. 1 and 2 Typn of Document:
Technical Evaluation Report Author (s):
D. A. Weber Data of Document:
April 1981 Responsible NRC Individual and NRC Office or Division:
Paul C. Shemanski, Division of Licensing Tnis document was prepared primari!y for preliminary or internal use. it has not received full review and approval. Since there may be substantive changes, this document should-not be considered final.
EG&G Idaho. Inc.
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