NL-07-2108, Response to NRC Request Regarding Alternative ISI-ALT-08

Response to NRC Request Regarding Alternative ISI-ALT-08

ML073180031
Person / Time
Site:	Hatch
Issue date:	11/13/2007
From:	George B Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-07-2108
Download: ML073180031 (5)

Text

Southern Nuclear Operating Company, Inc.

Post Office Box 1295 Birmingham. Alabama 35201-1295 Tel 205.992.5000 SOUTHERN'\

COMPANY November 13, 2007 Energy to Serve Your WorldS" Docket No.: 50-321 NL-07-2108 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant - Unit 1 Response to NRC Request Regarding Alternative ISI-ALT-08 Ladies and Gentlemen:

Pursuant to your electronic mail request dated October 15, 2007, Southern Nuclear Operating Company (SNC) hereby provides its response concerning the projected fluence value for the limiting axial weld. ISI-ALT-08 (letter NL-07-0270, dated March 8, 2007) was submitted to extend the authorization for the elimination of the RPV circumferential shell weld examinations required by ASME Code through the renewed license period of extended operation (PEO) at Plant Hatch-Unit 1. The NRC request and the SNC response are provided in the enclosure to this letter.

This letter contains no NRC commitments. If you have any questions, please advise.

Sincerely,

~~~Manager, Nuclear Licensing BJG/MNW/daj

Enclosure:

1. Response to NRC Request Regarding Alternative ISI-ALT-08

U. S. Nuclear Regulatory Commission NL-07-2108 Page 2 cc: Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. D. R. Madison, Vice President - Hatch Mr. D. H. Jones, Vice President - Engineering RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Dr. W. D. Travers, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Hatch Mr. J. A. Hickey, Senior Resident Inspector - Hatch

Edwin I. Hatch Nuclear Plant - Unit 1 Response to NRC Request Regarding Alternative ISI-ALT-08 Enclosure 1

Enclosure 1 Response to NRC Request Regarding Alternative ISI*ALT*08 Restatement of NRC Request RE: Proposed Alternative for RPV Circumferential Weld Examinations, NL-07 0270 There is one more piece of data that is needed in order to authorize the request to extend the RV circumferential weld relief out through the end of the period of extended operation: SNC is requested to provide the updated 49.3 EFPY projected f1uence value for the limiting axial welds at Hatch 1 that were calculated using the NRC-approved RAMA fluence methodology. 49.3 EFPY is now the number of EFPYs corresponding to the end of the period of extended operation.

The reason we need this new end-of-Iife fluence for the axial welds is because the BWRVIP-05 provisions for eliminating circ. weld examination relief are based on the assumption that the limiting axial weld failure frequency would remain less than 5.0 EE-06 per reactor-year through the end of the period of extended operation. In order to demonstrate this, the licensee needs to provide a valid axial weld f1uenee value that results in an axial weld Mean RT-NOT value of less than 114 degrees F.

This request is similar to our original RAI on ISI-ALT-08, where we requested this data for the eire. welds. All we need is the new updated 49.3 EFPY limiting axial weld f1uence value.

E1 - 1

Enclosure 1 Response to NRC Request Regarding Alternative ISI-ALT-08 SNC Response for Plant Hatch - Unit 1 The projected fluence value calculated by RAMA for the limiting axial weld at the end of the period of extended operation (PEG) at Hatch 1 is 0.220 X 1019 n/cm 2 ,

with the end of the PEG being defined at 49.3 EFPY.

The Hatch Unit 1 mean RTNOT of 63.1 OF for the limiting axial weld is bounded by the mean RTNOT of 114°F assumed in the analysis to demonstrate an RPV failure frequency of approximately 5E-06 per reactor year.

Hatch 1 End of PEO 49.3 EFPY LimitinSI Axial Weld Fluence 0.220 (10 19 n/cm2) l\RTNOT (OF) 113.1 RTNOT(U) (OF) -50 Mean RTNOT CUF) 63.1 E1 - 2