ML15223A762
| ML15223A762 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 12/01/1981 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | Parker W DUKE POWER CO. |
| References | |
| NUDOCS 8112220067 | |
| Download: ML15223A762 (4) | |
Text
pEUIBER 0'IK DISTRIBUTION:
NSIC ACRS-10 Docket File-3 ORB#4 Rdg HOrnstein NRC PDR DEisenhut EBlackwood L.PDR PWagner Gray File TERA RIngram Dockets Nos. 50-269, 50-27Sri nivasan RPrevatte and 50- 28 7 ELD AEOD IE-3 Mr. William 0. Parker, Jr.
Vice President - Steam Production Duke Power Company P. 0. Box 33189 422 South Church Street Charlotte, North Carolina 28242
Dear Mr. Parker:
We have reviewed your January 31, 1980 and June 4, 1980 submittals regarding the adequacy of offsite power systems and degraded grid voltage, which were in response to NRC letters dated August 8, 1979 and May 5, 1980.
Our review has determined that sufficient detail has not been provided to enable us to complete our evaluation. There fore, we request that you provide, Within 45 days of your receipt of this letter, responses to the enclosed request for additional Infor mation.
Because of the scope of this request, it may be advantageous to conduct a conference call between NRR, NRR Consultants (EG&G) and members of your organization to clarify what information is needed. Please contact your NRC Project Manager to establish such a call if you deem one to be desired or if you have any other questions on this subject.
Since this request is related qnly to the Oconee Nuclear Station, the response affects fewer than ten resppndants and therefore, 0MB clearance is not required under P. L.96-511.
Sincerely, John F. Stolz, Chief Operating Reactors Branch 764 Division of Licensing
Enclosure:
Request for Additional Information cc w/enclosure:
See next page ORB#4:D C-0RB#4:DL OFFICE su.n..
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OFFICIAL RIECORD COPY IusGPo). 1981-335-S
Duke Power Company cc w/enclosure(s):
Mr. William L. Porter Duke Power Company P. 0. Box 33189 422 South Church Street Office of Intergovernmental Relations Charlotte, North Carolina 28242 116 West Jones Street Raleigh, North Carolina 27603 Oconee County Library 501 West Southbroad Street Walhalla, South Carolina 29691 Honorable James M.'Phinney County Supervisor of Oconee County Walhalla, South Carolina 29621 Regional Radiation Representative EPA Region IV 345 Courtland Street, N.E.
Atlanta, Georgia 30308 Resident Inspector U.S. Nuclear Regulatory Commission Route 2, Box 610 Seneca, South Carolina 29678 Mr. Robert B. Borsum Babcock & Wilcox Nuclear Power Generation Division Suite 220, 7910 Woodmont Avenue Bethesda, Maryland 20814 Manager, LIS NUS Corporation 2536 Countryside Boulevard Clearwater, Florida 33515 J. Michael McGarry, III, Esq.
DeBevoise & Liberman 1200 17th Street, N.W.
Washington, D. C. 20036
E4r URE REQUEST FOR ADDITIONAL INFORMATION REGARDING THE ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES OCONEE UNITS 1, 2, AND 3 References
- 1. Duke Power letter, William 0. Parker, Jr. to Harold R. Denton, dated January 31, 1980
- 2. Duke Power letter, William 0. Parker, Jr. to Harold R. Denton, dated June 4, 1980
- 1. The scenario at Oconee where an outage of one startup transformer can automatically cause a remaining transformer to overload by 167% and bus voltages to drop below 85% is alarmingly similar to the situation which occurred at Arkansas Nuclear One. As ESG loads are added (Ref. 1, Fig. 4) motor voltages in some instances could be below 80%. At this voltage level, the staff is aware from reports at Millstone that some MCC contactors did not pick-up and this caused control transformers to overload and control fuses to blow.
Also, if degraded voltages are sustained, motor heaters and possibly some motor circuit overcurrent protective devices will open and ESG loads will be dropped. Provide justification supported by analysis and data that substantiates your claim that there will not be spurious operation of controls, breakers or blown fuses (if used) during the postulated low voltage condition at the motors.
- 2.
On page 4, paragraph 2 of Ref. 2, you indicate that the ESG motors can operate at 80% voltage for four hours with minimal loss of life. The staff is unable to corroborate this statement with published information.
Provide your analysis, manufacturer's data and references to enable the staff to verify this statement. Data submitted should include manufacturer's curves of motor undervoltage versus temperature rise at rated loads, Arrhenius plots of expected life versus temperature, speed/
torque curves, or results of tests performed by you or others.
- 3. In your January 31, 1980 submittal, response #5 states that MCC fuses will not blow when motors are operated at 90% nominal voltages (worst case condition of the Oct. 29, 1979 analysis). The worst case condition of the June 4, 1980 submittal produced voltage levels substantially lower than those produced by the October 29, 1979 analysis. Have the fuses, motor contactors, and control transformer been tested at these lower voltages to substantiate the statement in Ref. 2, page 5, paragraph III 4?
-2
- 4.
Justify that the motor-operated-valves will perform satisfactorily at the lowest voltages experienced at the 208 volt MCC's noted in the Reference 2 tables.
- 5. Provide your estimated date for submitting the results of your testing of valves and valve operators under degraded voltage (Ref. 2, page 4, paragraph 3).
- 6. Are there other 1E equipment such as battery chargers or electronic equipment which could impose a more severe voltage limitation on the IE buses then the motors?
- 7. In Reference 2, Figures 1-4, 7, and 8, does the per unit voltage motor base take into account the feeder voltage drop from MCC to the motor? If not, then the per unit'values in this column are overstated and-should be recalculated considering feeder voltage drop.
- 8. What is the minimum pick-up voltage and hold-in voltage of the MCC contactors as determined by the manufacturer's tests (Ref. 2, Page 5, paragraph 4 and Ref. 1, item 3).
- 9. When the voltages of Ref. 2, tables 1 and 2 were recorded, what was the load on the distribution buses.
(The load on the distribution buses should have been at least 30%.)
- 10.
What assurances can you give that there will be close correlation between calculated and actual voltages at Units 1 and 2, based on the results of the Unit 3 correlation tests.
- 11. Avoltageanalysis using either CT4 or CT5 as the source of the 4160 volt ESG power for three units should be provided.
- 12. The proposed reduction in second-level undervoltage protection setpoints from 88% to 77% (80%-3% relay tolerance) is unacceptable unless manufacturers documentation or testing results by Duke Power Company can be provided for NRC revtew that clearly demonstrate that all Class 1E equipment can operate continuously at this degraded voltage level without damage or a significant reduction in.equipment life.