ML20211P690
| ML20211P690 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 02/24/1987 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 86-477B, NUDOCS 8703020416 | |
| Download: ML20211P690 (3) | |
Text
l VIRGINIA ELECTRIC AND l'OWER COMPANY Hacitwonn,VanoixrA 20201 W.L.STEWANT Vaca Passinswy Nect. man orsmations February 24, 1987 United States Nuclear Regulatory Commission Serial No.
86-477B Attention: Document Control Desk E&C/BSD/KKD/psj :0139 Washington, D.C.
20555 Docket Nos.
50-338 50-339 License Nos.
NPF-4 NPF-7 Centlemen:
VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 PROPOSED LICENSE AMENDNENT-CDC4 ADDITIONAL INFORMATION Virginia Electric and Power Company requested an amendment, to Operating License Nos. NPF-4 and NPF-7 for the North Anna Power Station Units 1 and 2, by letter dated November 6,
1986 (Serial No. 86-477A). The November 6, 1986 letter also transmitted the supporting technical evaluations, including Westinghouse Electric Corporation Report, " Technical Bases for Eliminating Large Primary Loop Pipe Rupture as a Structural Design Basis for North Anna Units 1 & 2," WCAP-11163. The proposed amendment would add a license condition stating that the design of the reactor coolant pump and steam generator supports may be revised in accordance with our November 6, 1986 submittal.
Discussions were held between members of our respective staffs concerning our requested license change during telephone conferences on January 23, 1987 and February 5,1987.
The NRC requested additional information during these discussions. The attachment to this letter restates the two specific NRC questions and provides our response to one question and a commitment to provide a response to the second question by March 12, 1987.
Virginia Electric and Power Company appreciates your continued efforts in this matter.
Very truly yours, W. L. Stewart Attachment
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8703020416 870224 PDR ADOCK 05000338 i
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cc:
U. S. Nuclear Regulatory Commission 101 Marietta Street, N.W.
Suite 2900 Atlanta, CA 30323 Mr. J. L. Caldwell NRC Senior Resident Inspector North Anna Power Station
ATTACHMENT NRC REQUEST FOR ADDITIONAL INFORMATION CONCERNING REDESIGN OF CERTAIN COMPONENT SUPPORTS NRC REQUEST (1) Provide the reason for the difference in values of stress between Table 3-8 of WCAP-11163 and Table 1 of Attachment 3 to the November 6, 1986 Virginia Electric and Power Company letter (Serial No. 86-477A).
RESPONSE
(1) The calculated stresses in Table 3-8 of WCAP-11163 are combinations of deadweight, pressure and seismic loads, but do not include loads for mainsteam, feedwater and remaining reactor coolant system branch line ruptures. This combination of loads has been presented in previous Westinghouse WCAPs 9558 and 9787 referenced in our letter dated August 5, 1986 (Serial No.86-477).
The faulted values in Table 1 of Attachment 3 to our November 6, 1986 letter are a combination of deadweight, pressure, and the square root of the sum of the squares (SRSS) of Safe Shutdown Earthquake (SSE) and remaining governing pipe ruptures. This final term is not included in the WCAP values. This explains the difference in the two tables.
NRC REQUEST (2) Provide additional information on the capacity and margins of safety for RCS support system snubbers, rigids, steam generator and reactor coolant pump support structures and their anchorages for the following five (5) scenarios (similar to Table 3 of Attachment 3).
(a) existing support configuration during LOCA (b) existing support configuration without LOCA but with remaining pipe ruptures (c) proposed support configuration, same as (b) above (d) existing support configuration, loaded with pressure,
- thermal, deadweight and SSE.
(e) proposed support configuration, same as (d) above.
RESPONSE
(2) Our response will be provided by March 12, 1987.