ML20064F120
| ML20064F120 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 11/22/1978 |
| From: | David Williams ARKANSAS POWER & LIGHT CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| 2-118-12, NUDOCS 7811280232 | |
| Download: ML20064F120 (2) | |
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-Q ARKANSAS POWER & LIGHT COMPANY POST OFRCE BOX 551 UTTLE ROCK. ARKANSAS 72203 (501)371-4000 November 22, 1978 2-118-12 Director of Nuclear Reactor Regulation ATTN:
Mr. J. F. Stolz, Chief Light Water Reactors Branch #1 U. S. Nuclear Regulatory Commission Washington, D. C.
20555
Subject:
Arkansas Nuclear One-Unit 2 Docket No. 50-368 p License No. NPF-6 Conformance to GDC-17 (File:
2-6012, 2-1510)
Gentlemen:
Our letter of November 6,1978, transmitted our interim commitment which was intended to alleviate the Staff's concerns in regard to conformance of ANO-2 to GDC-17. As a result of conversations with the Staff, subsequent to the above letter, the following clarification is provided.
The total loading set to automatically transfer to Startup Transformer #2 (SU2), will not result in a loading of SU2 that would result in a loss of SU2 due to overheating and will na result in unacceptable voltages at the safety buses under worst case grid conditions and plant auxiliary load conditions.
k To date, we have not completed our analyses which substantiates the maximum loading on SU2 which will not result in an undervoltage condition at the safety buses considering worst case grid conditions. We have, however, completed analysis which substantiates 34 MVA as an acceptable loading within these constraints. Therefore, until we have completed all analyses, we will consider 34 MVA as a maximum.
Controls, to implement this commitment by Mode 2 operation, will be adminis-trative in the form of the plant procedures and will function as follows:
Analyses will be performed to determine possible breaker combinations that would allow loads (within the above limits) to automatically transfer to SU2. These breaker combinations will be incorporated in our plant procedures as the only allowable breaker combinations. Should we desire possible different combinations, analyses will be performed and, provided the com-bination meets the above criteria, incorporated in the procedures.
O0 q, 6 O " Q c
.oO MEMBEA MiOOLE SOUTH UT1uTIES SYSTEM
Mr. J. F. Stolz November 22, 1978 To date, the " worst case" breaker combination is as follows:
I l
Bus Breaker Position Load Al Pull to Lock (PTL) 0 A2 PTL 0
H1 PTL 0
H2 PTL 0
2A1 PTL 0
2A2 Availabic to Close 10 MVA 2H1 PTL 0
2H2 Available to Close 18 MVA This breaker arrangement allows 28 MVA to automatically transfer to SU2, which is below the 34 MVA maximum.
Verification of breaker alignments will be as stated in our letter of November 6, 1978, on the above subject.
If a postulated LOCA was to occur at ANO-2 concurrent with an automatic transfer to SU2, all running 4160 volt loads would be 'shed ~and"the safety loads would be sequenced onto the 4150 volt Buses.
In the above breaker arrangement, 2A1 will be in pull-te-lock, 2DG1 will sup,cly safety bus 2A3 and SU2 will supply buses 2A2 and 2A4.
Very truly yours, Daniel H. Williams Manager, Licensing DHW:JTE:vb
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