ML18026B085

Forwards Request for Addl Info Re Adequacy of Station Electric Distribution Sys Voltages.Assessment of in-plant Voltages,Discussion of Approach to Resolve Condition & Estimate for Submittal of Design Info Requested in 45 Days

ML18026B085
Person / Time
Site:	Browns Ferry
Issue date:	06/19/1984
From:	Vassallo D Office of Nuclear Reactor Regulation
To:	Parris H TENNESSEE VALLEY AUTHORITY
References
NUDOCS 8407100320
Download: ML18026B085 (4)

Text

June 19, 1984 Docket Nos. 50-259/260/296 Re:

Browns Ferry Nucl ear Pl ant, Units 1, 2 and 3

Mr. Hugh G. Parris Manager of Power Tennessee Valley Authority 500A Chestnut Street, Tower II Chattanooga, Tennessee 37401

SUBJECT:

ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES - VERIFICATION TESTING DISTRIBUTION NRC PDR Local PDR ORB¹2 Reading DEisenhut OELD SNorris RClark WLong ELJordan JNGrace ACRS (10)

Gray File MSrinivasan Your letter of March 19, 1984 responded to our request for additional information of January 6,

1984 on the above subject.

As discussed with your staff, your response did not resolve the consequences of a potential over-voltage condition under some conditions when using the backup 161 KV offsite power source.

This letter formalizes the request for additional information discussed with your staff; the analysis requested is identified in the enclosure to this letter.

You are requested to review this potential over-voltage condition.

Within 45 days of receipt of this letter, please 'provide your assessment of the inplant voltages, a discussion of the general approach you plan to follow to resolve this potential condition and an estimate of when you expect to submit design information on any proposed modifications.

This request for additional information is specific to one licensee.

The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required under P.L.96-511.

Sincerely, Original signed by/

Enclosure:

As stated Domenic B. Vassallo, Chief Operating Reactors Branch ¹2 Division of Licensing cc w/enclosure:

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Mr. Hugh G. Parris Tennessee Valley Authority Browns Ferry Nuclear Plant, Units 1, 2 and 3

CC:

H. S. Sanger, Jr., Esquire General Counsel Tennessee Valley Authority 400 Commerce Avenue E 11B 330 Knoxville, Tennessee 37902 Mr. Ron Rogers Tennessee Valley Authority 400 Chestnut Street, Tower II Chattanooga, Tennessee 37401 Mr. Charles R. Christopher

Chairman, Limestone County Commission Post Office Box 188

Athens, Alabama 35611 U. S. Environmental Protection Agency Region IV Office Regional Radiation Representative 345 Courtland Street, N.

W.

Atlanta, Georgia 30308 Resident Inspector U. S. Nuclear Regulatory Commission Route 2, Box 311

Athens, AlabBNa 35611 Mr. Donald L. Williams, Jr.

Tennessee Yal 1ey Authority 400 West Summit Hill Drive, W10885 Knoxville, Tennessee 37902 Ira L. Myers, M. D.

State Health Officer State Department of Public Health State Office Building Montgomery, Alabama 36130 Mr. H. N. Culver 249A HBD 400 Commerce Avenue Tennessee Yalley Authority Knoxville, Tennessee 37902 James P. O'Reilly Regional Administrator Region II Office U. S. Nuclear Regulatory Commission 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 George Jones Tennessee Valley Authority Post Office Box 2000

Decatur, Alabama 35602 Mr. Oliver Havens U. S. Nuclear Regulatory Commission Reactor Training Center Osborne Office Center, Suite 200 Chattanooga, Tennessee 37411

ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES BROWNS FERRY NUCLEAR PLANT, UNITS 1, 2 AND 3 DOCKET NOS. 50-259/260/296

References:

1.

TVA letter, L. M. Mills to H. R. Denton, NRC, March 19, 1984.

2.

TVA letter, L. M. Mills to H. R. Denton, NRC, September 22, 1983.

3.

TVA letter, L. M. Mills to H.

R. Denton, NRC, April 9, 1981, TVA BFNP TS 156.

4.

NRC letter, W. Gammill to TVA, "Adequacy of Station Electrical Distribution Systems Voltages," August 8, 1979.

Discussion:

References 1,

2 and 3 are in response to Reference 4.

We are concerned with the situation of the 161 KV grid, which we understand is nominally maintained between 166 and 168 KV.

Your analysis shows that the switchyard voltage must be maintained above 166 KV to assure adequate voltage to the safety loads in the event of maximum electrical loading during an accident situation.

Your testing shows that with the switchyard at 166 KV, the 480V safety loads can be subjected to voltages in excess of their ratings (Reference 3 shows that at no load, 533V is possible).

These loads are normally powered by the unit generator or the 500 KV grid.

Anal ses Re uested Show that the 480V equipment (by looking at the most limiting equipment) will not have its service unjustifiably shortened by the described over-voltage conditions so as to cause failure during a later accident situation.