ML20248D300

Suppl to 890817 Response to Station Blackout Rule,Addressing NRC Comments from Review Team Exit Meeting on 890818. Reliability Program for Gas Turbine Being Developed & Includes 95% Reliability Goal & Quarterly Turbine Testing

ML20248D300
Person / Time
Site:	Point Beach
Issue date:	09/26/1989
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-89-114 TAC-68586, TAC-68587, VPNPD-89-511, NUDOCS 8910040186
Download: ML20248D300 (3)

Text

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h .AV Wisconsin Electnc POWER COMPANY 231 W Michigan. Po. Box 2046. Mitwoukee. WI 53201 (414)221-2345

-VPNPD-89-511 NRC-89-114-September 26, 1989 Document Control Desk 10 CFR 50.63 U. S. Nuclear Regulatory Commission Mail Station Pl-137 Washington, D.C. 20555 Gentlemen:

DOCKET NOS. 50-266 AND 50-301 i SUPPLEMENT TO 10 CFR 50.63, TAC. NOS. 68586 AND 68587 j LOSS OF ALL ALTERNATING CURRENT POWER POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 On April 17, 1989, Wisconsin Electric submitted a letter to the NRC responding to 10 CFR 50.63, " Loss of All Alternating Current Power,"

for. Point Beach Nuclear Plant. On August 15 to 18, 1989, an NRC review team audited the documentation supporting the Wisconsin Electric. response to the Station Blackout Rule. This letter is a supplement to the Wisconsin Electric response dated April 17, 1989, and is intended to address the comments made by the NRC review team at the exit meeting on August 18, 1989. It provides additional information about the Point Beach Nuclear Plant alternate AC (AAC) power source, the loss of ventilation evaluations, the maintenance of emergency diesel generator (EDG) reliability, and quality assurance for non-safety equipment.

As stated in the April 17 letter, the AAC power source at Point Beach is a 20 MWe gas turbine generator.. The reliability of the gas turbine generator was calculated to be approximately 0.91 as determined by guidance from NSAC-108. Regulatory Guide (RG) 1.155 and NUMARC 87-00 state that the reliability of an AAC power system  ;

should meet or exceed 95 percent.

A reliability program for the gas turbine is being developed to improve the gas turbine generator reliability. The reliability program includes: establishment of the 95% reliability goal, testing on at least a quarterly basis, maintenance practices that support l the reliability goal, establishment of a QA program based on j guidance from Appendix A of RG 1.155, and identification of  !

responsibilities in the program. If achievability of the 95% goal cannot be demonstrated within two years of the receipt of the NRC SER on station blackout for Point Beach, the use of the gas turbine generator as an AAC power source will be reassessed at that time.

Also, all elements of the reliability program are expected to be implemented within two years.

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US NRC Document Control Desk September 26, 1989 Page 2 On August 24 and September 21, 1989, blackout load tests of the gas turbine generator were performed. During the tests, the gas turbine building ventilation was confirmed to be inadequate because the auxiliary power diesel generator overheated. The auxiliary diesel supplies power to the control systems and auxiliaries for the gas turbine generator. A modification is now-planned to improve the ventilation near the auxiliary power diesel generator. Another 8-hour duration test will be performed when the ventilation-modification is complete. The modification and testing should be complete by June 1990.

The station blackout loss of ventilation temperature calculations and equipment operability evaluations are about to be performed. As stated, it is expected that these evaluations will confirm that the temperature rises in the main areas of concern will not adversely .

affect equipment required to maintain both units in a safe shutdown condition for the required station blackout coping duration of eight hours. These evaluations were not performed earlier because we are not using the NUMARC 87-00 methodology and we prefer to do these evaluations in conjunction with evaluations being performed for NRC Generic Letter (GL) 88-20, " Individual Plant Examination for Severe Accident Vulnerabilities." We intend to perform detailed time-dependent, room-temperature analyses to assess the need to restore ventilation and the priority of restoration. These time-dependent analyses should be a more accurate method of determining temperatures and assessing true operability impact than the NUMARC 87-00 4-hour steady-state methodology. Also, it will be more efficient to perform these evaluations in conjunction with evaluations for GL 88-20. These evaluations will be completed by March 31, 1990.

The reliability of the Point Beach emergency diesel generators is i better than the target of 0.975. The reliability is verified by testing the units in accordance with Point Beach Technical Specifications. The reliability is maintained by annual maintenance on each unit and trouble-shooting as necessary. These methods for maintaining EDG reliability will be evaluated against the NRC recommendations for maintaining EDG reliability when NRC Generic j Issue B-56, " Emergency Diesel Reliability," is resolved. I A quality assurance program, based on the guidance from Regulatory  !

Guide 1.155 Appendix A, will be implemented for non-safety equipment used to cope with a station blackout. For Point Beach, the AAC j power source is an example of a non-safety system that would be relied upon to maintain safe shutdown of both units and would be included in the QA program.

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US NRC Document control Desk September 26, 1989 Page 3 During the Station Blackout Rule documentation review, we advised the NRC team members that there may be an error in the extremely severe weather data for Point Beach. This possible error in NUMARC 87-00 places Point Beach in extremely severe weather (ESW) group 4.

It is believed that Point Beach is more appropriately classified in ESW Group 1 or 2. Wisconsin Electric may amend the April 17, 1989, submittal if the data error is confirmed.

l We would be pleased to answer any questions regarding the above  !

information.

Very truly yours, ye y C. W.. Fay Vice President Nuclear Power Copies to NRC Regional Administrator - Region III NRC Resident Inspector