ML19209C262

Responds to NRC 790808 Ltr Re Adequacy of Station Electric Distribution Sys Voltages.Util Conducting Voltage Study Using NRC-required Approach.Study Will Take Addl 60 Days for Completion

ML19209C262
Person / Time
Site:	Peach Bottom
Issue date:	10/05/1979
From:	Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Gammill W Office of Nuclear Reactor Regulation
References
NUDOCS 7910120302
Download: ML19209C262 (2)

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PHILADELPHIA ELECTRIC COMPANY 2301 M ARKET STREET P.O. BOX 8699 PHILADELPHIA. PA.19101 SHIELOS L. D ALTROFF ELacinic Pm o c son October 5, 1979 Re: Docket Nas. 50-277 50-278 Mr. William Gammill, Acting Assistant Dir<.ctor for Operating Reactorc Project Division of Operating Reactors U.S. Nuclear Regulatory Ccamission ,

Washington, DC 20555

Reference:

1) Letter S. L. Daltroff, PECO, to G. Lear, NRC, September 15, 1976. Responsa to NRC letter dated August 11, 1976.

2) Letter S. L. Daltroff, PECO, to G. Lear, NRC, July 21, 1977. Response to NRC letter dated June 2, 1977.

3) Application for Amendment of Facility Operating Licenses DPR-44 and DPR-56, Letter E. J. Bradley, PECO, te NRC, December 22, 1977.

Requested by NRC letter dated June 2, 1977.

Dear Mr. Gammill:

This letter is in response to your letter dated August 8, 1979, concerning the Adequacy of Station Electric Distribution Systems Voltages. Philadelphia Electric Company has addressed some of your concerns in our letters of September 15, 1976, July 21, 1977, and the amendment to Technical Specifications request of December 22, 1977. In this correspondence, we have established that our system as designed and tested meets GDC -

17. Further, in our amendment request dated December 22, 1977, we agreed to add a second level of under-voltage protection. We recently received NRC approval to implement this-modificatioc.

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Mr. W. Gammill

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'four request of August 8, 1979, requires a more rigorous analysis of our power syatem for effects of degraded "oltage conditions than was performed previously. Currently, our Electrical Engineering Division is conducting a voltage study using the rigorous approach detailed in your Enclosure 2. This study is of such depth that an additional 60 days will be required for its completion.

Your letter also asks that we verify the results of our analysis by tests. We are concerned about the safety and practienlity of conducting such a test on the plant electrical system under degraded voltage conditions. However, we will determine the feasibility of such tests after we have finished the degraded voltage study.

Additionally, your letter requested that we again review our electrical power system for effects on conditions which could result in simultaneous loss of both off-site power sources. We have conducted this review and confirm that our previous response is correct. Since our sources are physically separated and diverse in origin (One from the 220 kv system and one from the 500 kv system), no potential for violation of GDC - 17 has been identified.

Should you have any additional questions or desire to discuss the specifics of our design, please feel free to contact us.

Very truly yours,

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