ML19321A694
| ML19321A694 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 06/27/1980 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO. |
| References | |
| NUDOCS 8007240073 | |
| Download: ML19321A694 (5) | |
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UNITED STATES i
NUCLEAR REGULATORY COMMISSION y
g WASHINGTON, D. C. 20655 n
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June 27, 1980 Docket No. 50-245 Mr. W. G. Counsil
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Nuclear Engineering & Operations Connecticut Yankee Atomic Power Co.
P.O. Box 270 Hartford, Conner '#:ut 06101
Dear Mr. Counsil:
We are continuing our review of the adequacy of station electric distribution system voltages for Millstone Unit No. I and have found that additional information described in the enclosure to this letter is needed. We request your response within 45 days of your receipt of this letter.
Sin erely.
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. Crutch iel,
'i e Operating Reactors Bra h #5 Division of Licensing
Enclosure:
Request for Additional Infonnation cc w/ enclosure:
See page 2 l
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8007240023
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Mr. W. G. Counsil June 27, 1980 cc w/ enclosure:
William H. Cuddy, Esquire Connecticut Energy Agency Day, Berry & Howard ATTN: Assistant Director Counseloi; at Law Research and Policy One Constitution Plaza Development Hartford, Connecticut 06103 Department of Planning and Energy Policy Anthony Z. Roisman 20 Grand Street i
Natural Resources Defense Council Hartford, Connecticut 06106 91715th Street, N. W.
Washington, D. C.
20005 Director, Technical Assessment Division Northeast Nuclear Energy Company Office of Radiation Programs ATTN: Superintendent (AW-459)
Millstone Plant U. S. Environmental Protection P. O. Box 128 Agency Waterford, Connecticut 06385 Crystal Mall #2 Arlington, Virginia 20460 Mr. Japes R. Himmelwright Northeast Utilities Service Company U. S. Environmental Protection P. O. Box 270 Agency
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Hartford, Connecticut 06101 Region I Office ATTN: EIS COORDINATOR Resident Inspector JFK Federal Building c/o U. S. NRC Boston, Massachusetts 02203 P. O. Box Drawer KK Niantic, Connecticut 06357 Waterford Public Library Rope Ferry Road, Route 156 Waterford, Connecticut 06385 First Selectman of the Towf.-
of Waterford Hall of Records 200 Boston Post Road Waterford, Connecticut 06385
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REQUEST FOR ADDITIONAL INFORMATION MILLSTONE #1 ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES i
Ref. 1: NRC letter (W. Cammill) to all Power Reactor Licensees, dated August 8, 1979 I
Ref. 2: Attr.chment 2 of Northeast Utilities letter (W. G. Counsil) to NRC (D. L. Ziemann), dated November 15, 1979 1.
Guidelines 1 and 7 (Ref. 1) require that a separate analysis be per-formed for all available connections to the offsite network and that the analysis be adequately documented for each condition analyzed.
Ref. 2 does not fully meet these requirements. To confirm the acceptibility of the voltage conditions on the station electric dis-tribution system, submit adequate voltage analysis documentation for those cases and conditions analyzed in Ref. 2 and additional documenta-tion specifically:
a.
Requirements of Guidelines 6 and 11 as well as 5 and 13 (Ref.1) must be included in each separate case analyzed.
These guidelines refer to the use of minimum and maximum expected grid voltages, maxi-mum loads assumed for each analyzed case, and a list of assumptions for each analyzed case.
b.
Supply the calculated voltages for all low-voltage AC (less than 480 volts) Class lE buses (include all available sources) for each case analyzed. Do these buses espply and instruments or control
-circuits as required by GDC 13'.
If so, is all equipment capable of sustaining the analyzed voltages without blowing fuses, overheating, and without affecting the equipment's ability to perform the required function?
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. c.
Per Guidelines 3 and 9 <xef. 1), compare the effect of starting and running the largest non-Class 1E load on all Class lE buses and loads with the required voltage range for normal operation e
of all Class 1E equipment (starters, contactors, motors, etc.)
for each available connection of offsite sources.
This comparison should occur after the Class lE buses are fully loaded.
d.
Ref. 2, Page 3, Item a identiiles that a source connection to the Class lE buses exists by backfeeding from the 345 KV switchyard through the main transformer and transformer NSST-1.'
A complete analysis is required for this source connection.
Ref. 2, Page 2, Paragraph 2 identifies the alternate offsite supply e.
as SDT-1 which is fed from a 23 KV feeder from Flanders 11 Y sub-station. An analysis is required for this available source con-nection or identify limiting conditions of operation. What is the normally expected voltage range of this 23 KV feeder?
f.
From the sketches of the auxiliary buses submitted in Ref. 2 (Millstone #1 and Millstone #2), it appears there are two possible source connections to the Class lE buses from transformers RSST-2 and NSST-2 (Millstone #2) via the link from transformer RSST-1.
An analysis is required for these source connections unless inter-Locks prevent the connection or limiting conditions of operations are identified.
2.
Ref. 2, Pages 3 and 4 identifies four separate conditions when thb +10%
overvoltage capability of the mouors on the 480-volt buses is exceeded.
Installation of overvoltage monitors is planned to initiate operator
A
' O corrective action.
Credit will be given for this corrective action only if the overvoltage monitors and alarms are Class lE, and in the interim period of correction the overvoltage condition does not shorten equipment life or affect the Class 1E equipment's ability to perform the required function.
Provide documentation which demonstrates the equip-ment can meet these overvoltage conditions.
3.
Ref. 2, Page 5, Paragraph 1 states that the setpoint of the second level of undervoltage protection will be reset to the new value of 336 KV (switchyard voltage). The design of the second-level of undervoltage protection must meet the requirements of IEEE 297-1971. Provide the undervoltage and time setpoints in terms of Class lE nominal bus voltage and compare these setpoints as required in Guidelines 10 and 12 (Ref. 1).
4.
Raf. 2, Page 5, Paragraph 2 refers to the addition of a second second-level of undervoltage protection when the transformer RSST-1 is carrying Millstone #2 shutdown loads and Millstone #1 Normal and LOCA loads.
The design of the second-level of undervoltage (NRC Staff Position 1, June 2, 1977 letter) is to protect all Class lE equipment from grid 4
voltage degradation under all modes of operation. Explain in detail why this second second-level protection scheme is necessary.
5.
Submit a voltage analysis which meets Guideline 2 (Ref.1); that is Unit #1 is experiencing an accident or anticipated transient with the simultaneous shutdown of Unit #2 for all available source conditions.
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