ML13077A390

Response to Request for Additional Information (RAI 54) Regarding Confirmatory Action Letter Response

ML13077A390
Person / Time
Site:	San Onofre
Issue date:	03/15/2013
From:	St.Onge R Southern California Edison Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC ME9727
Download: ML13077A390 (5)

Text

SOUTHERN CALIFORNIA Richard J. St. Onge I EiSONl Director, Nuclear Regulatory Affairs and E IO Emergency Planning An EDISON INTERNATIONAL Company March 15, 2013 10 CFR 50.4 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

Docket No. 50-361 Response to Request for Additional Information (RAI 54)Regarding Confirmatory Action Letter Response (TAC No. ME 9727)San Onofre Nuclear Generating Station, Unit 2

References:

1. Letter from Mr. Elmo E. Collins (USNRC) to Mr. Peter T. Dietrich (SCE), dated March 27, 2012, Confirmatory Action Letter 4-12-001, San Onofre Nuclear Generating Station, Units 2 and 3, Commitments to Address Steam Generator Tube Degradation

2. Letter from Mr. Peter T. Dietrich (SCE) to Mr. Elmo E. Collins (USNRC), dated October 3, 2012, Confirmatory Action Letter -Actions to Address Steam Generator Tube Degradation, San Onofre Nuclear Generating Station, Unit 2 3. Email from Mr. James R. Hall (USNRC) to Mr. Ryan Treadway (SCE), dated February 21, 2013, Request for Additional Information (RAls 53-67) Regarding Response to Confirmatory Action Letter, San Onofre Nuclear Generating Station, Unit 2

Dear Sir or Madam,

On March 27, 2012, the Nuclear Regulatory Commission (NRC) issued a Confirmatory Action Letter (CAL) (Reference

1) to Southern California Edison (SCE) describing actions that the NRC and SCE agreed would be completed to address issues identified in the steam generator tubes of San Onofre Nuclear Generating Station (SONGS) Units 2 and 3. In a letter to the NRC dated October 3, 2012 (Reference 2), SCE reported completion of the Unit 2 CAL actions and included a Return to Service Report (RTSR) that provided details of their completion.

By email dated February 21, 2013 (Reference 3), the NRC issued Requests for Additional Information (RAIs) regarding the CAL response.

Enclosure 1 of this letter provides the response to RAI 54.P.O. Box 128 San Clemente, CA 92672 041-Document Control Desk-2-March 15, 2013 There are no new regulatory commitments contained in this letter. If you have any questions or require additional information, please call me at (949) 368-6240.Sincerely,

Enclosure:

1. Response to RAI 54 cc: E. E. Collins, Regional Administrator, NRC Region IV J. R. Hall, NRC Project Manager, SONGS Units 2 and 3 G. G. Warnick, NRC Senior Resident Inspector, SONGS Units 2 and 3 R. E. Lantz, Branch Chief, Division of Reactor Projects, NRC Region IV ENCLOSURE 1 SOUTHERN CALIFORNIA EDISON RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RESPONSE TO CONFIRMATORY ACTION LETTER DOCKET NO. 50-361 TAC NO. ME 9727 Response to RAI 54 Page 1 of 3 RAI 54 In Reference 1, Figures 4-11 and 4-13, the maximum depths in Figure 4-11 have been divided by the Unit 3 cycle length of 0.926 years to yield the growth rates in Figure 4-13. The staff understands that Figure 4-13 should be simply a scaled version of Figure 4-11. Please explain why some of the data in Figure 4-11 are not shown in Figure 4-13; for example, the three flaws shown in Figure 4-11 with maximum depths ranging from 89 to 100% (AREVA resized).RESPONSE RAI Reference 1 is the Operational Assessment for SONGS Unit 2 Steam Generators for Upper Bundle Tube-to-Tube Wear Degradation at End of Cycle 16," prepared by Intertek APTECH for Areva, Report No. AES 12068150-2Q-1, Revision 0, September 2012.The wear rates shown in Figure 4-13 were computed by dividing the tube-to-tube wear (TTW)maximum depths by the operating cycle length. The Staff is correct to state that Figure 4-13 is simply a scaled version of Figure 4-11 in RAI Reference

1. A few data points for corresponding wear rates fell above the 100% through wall (TW) per years at power. Figure 4-13 has a vertical axis range of zero to 100% TW per years at power so these points are not seen.Attached are the same graphs in Figure 4-13 with the wear rate axis extended to 120% TW per years at power. The three data points mentioned in the RAI are now visible.Page 2 of 3 ETSS 27902.2 Sizing 120 A 110 0 100 CL 90.80-70.60 S so o40 50 230 10 0 0 50 100 150 200 250 300 350 400 450 500 550 600 650 Wear Index, Wi (%TW)AREVA Resized 120 110 100 90 80 70 9 6 0 5070.40 0 3020 10 0 0 50 100 150 200 250 300 350 400 450 500 550 600 650 Wear Index, WI (%TW)Figure 4-13 -Tube-to-Tube Wear Rate as a Function of Wear Index Page 3 of 3 A