ML19249C768
| ML19249C768 | |
| Person / Time | |
|---|---|
| Site: | North Anna, 07001976  |
| Issue date: | 09/14/1979 |
| From: | Brown S VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Parr O Office of Nuclear Reactor Regulation |
| References | |
| RTR-REGGD-01.059, RTR-REGGD-1.059 723, NUDOCS 7909180486 | |
| Download: ML19249C768 (3) | |
Text
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Vepco September 14, 1979 Mr. Harold R. Denton, Director Serial No. 723 Office of Nuclear Reactor Regulation PSE&C/CES:adw:mc Atten: Mr. O. D. Parr, Chief Light Water Reactors Branch No. 3 Docket Nos. 50-404 Division of Project Management 50-405 U.S. Nuclear Regulatory Commission Washington, D. C.
20555
Dear Mr. Denton:
Our letter Serial No. 039 of February 6,1979 advised you of our intention to inform you continually of Company positions which are not in accordance with individual Regulatory Guides. This letter advises you of the Company position on Regulatory Guide 1.59, Revision 2,
" Design Basis Floods for Nuclear Power Plants" for the North Anna 3 and 4 units.
Comoany Position
~
North Anna Units 3 and 4 are not in full compliance with Regulatory Guide 1.59, Revisien 2.
The subject revision to the Regulatory Guide refers to the ANSI Sta.'
J N170-1976, " Standards for Determining Design Basis Flooding at Power Reactor Sites," as the document which should be used to develop the Probable Maximum Flood at inland loca-tions. The Combined Events Criteria, Section 9 of the referenced ANSI Standard, is the section to the Regulatory Guide where full compliance is not achieved.
In Section 9.2 of the ANSI Standard, a listing of ade-quate design basis combinations of flood-causing events is presented.
It is our position that both Section 9.2.1, which discusses Inland Streams, and Section 9.2.3, which discusses Enclosed Bodies of Water, are applicable to the North Anna site. Both Section 9.2.1 and 9.2.3 present several alternative combinations of meteorological events and both sections state that several alternatives should be mathematically tested.
The combination of events used in the Revised Analysis -
Probable Maximum Flood, Appendix J to the North Anna Units 1 and 2 Final Safety Analysis Report is the only combina-tion among the three alternatives listed in Section 9.2.1 which we consider applicable to N]rth Anna Units 3 and 4.
The combination used was:
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.4 Mr. Harold R. 'enton 2
J 1.
Mean monthly (base) flow 2.
Median soil moisture 3.
Antecedent rain = 50 percent of PMP 4.
PMP 5.
40 mph wind speed used for critical direction and length of effective fetch.
The combinations of events described in Section 9.2.3. have not been tested. These combinations of events are:
Alternative I 1.
One-half PMF 2.
Surge and eiche from the worst regional hurricane or windstorm <ith wind wave activity.
3.
100-year or maximum controlled level of water body, whichever is less.
Alternative II 1.
PMF 2.
25-year surge and seiche with wind wave actirity.
3.
100-year maximum controlled level of water body, whichever is less.
Alternative III 1.
25-year flood 2.
Probable maximum surge and seiche with wind wave activity.
3.
100-year or maximum controlled level of water body, whichever is less.
Initial inspection would indicate that the combination of events used in the Revised Analysis would be chosen as the most severe however, mathematical analyses have rc+ been performed for ver-i fication.
This position will be placed on file and will be included in the Final Safety Analysis Report for these units.
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.a Mr. Harold R. Denton 3
We would be pleased to discuss this position with you at your convenience. Should you wish to meet with us to discuss this posi-tion, or if you have any questions please contact us.
ry/ruly yours4/
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Senior Vice President Po'wer Station Engineering and Construction N w:0