RS-15-222, Response to Request for Additional Information Follow-up Clarification Regarding Relief Request 13R-14

Response to Request for Additional Information Follow-up Clarification Regarding Relief Request 13R-14

ML15211A530
Person / Time
Site:	LaSalle
Issue date:	07/30/2015
From:	Gullott D Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-15-222
Download: ML15211A530 (6)

Text

RS-1 5-222 10 CFR 50.55a July 30, 2015 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 LaSalle County Station, Units 1 and 2 Facility Operating License Nos. NPF-1 1 and NPF-1 8 NRC Docket Nos. 50-373 and 50-374

Subject:

Response to Request for Additional Information Follow-up Clarification Regarding LaSalle County Station Relief Request 13R-14

References:

1) Letter from D. M. Gullott (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "Proposed Alternative to the Examination Requirements for Nozzle-to-Vessel Welds and Inner Radii Sections in Accordance with 10 CFR 50.55a(z)(1)," dated January 29, 2015 (ADAMS Accession No. ML15030A175)

2) Letter from D. M. Gullott (Exelon Generation Company, LLC) to U. S. Nuclear Regulatory Commission, "Response to Request for Additional Information Regarding LaSalle County Station Relief Request 13R-1 4," dated June 8, 2015 (ADAMS Accession No. ML15160A611)

3) Email from B. Vaidya (U. S. Nuclear Regulatory Commission) to L. A. Simpson (Exelon Generation Company, LLC) and D. M. Gullott (Exelon Generation Company, LLC), "LaSalle Units 1 and 2, TAC Nos. MF5654 and 5655, FOLLOW-UP RAI," dated June 30, 2015 In Reference 1, Exelon Generation Company, LLC (EGC) submitted relief request (RR) 13R-1 4 for LaSalle County Station (LSCS), Units 1 and 2. RR I3R-14 is intended to apply American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (ASME Code), Code Case N-702, "Alternative Requirements for Boiling Water Reactor (BWR) Nozzle Inner Radius and Nozzle-to-Shell Welds," to reactor pressure vessel nozzles at LSCS. EGC supplemented Reference 1 with a letter dated June 8, 2015 (Reference 2).

In Reference 3, the U. S. Nuclear Regulatory Commission (NRC) provided a follow-up RAI related to its review of RR 13R-1 4. Attachments 1 and 2 of this letter provide the requested information.

July 30, 2015 U. S. Nuclear Regulatory Commission Page 2 There are no regulatory commitments contained within in this letter.

Should you have any questions concerning this letter, please contact Ms. Lisa A. Simpson at (630) 657-2815.

Respectfully, Z 2 ~~Oe~ '-

David M. Gullott Manager Licensing Exelon Generation Company, LLC Attachments:

1) Response to Request for Additional Information

2) Structural Integrity Associates, lnc. Report No. 1400187.401, Revision 0, Response to NRC RAI Regarding Stress Corrosion Cracking (SCC) Initiation Time cc: NRC Regional Administrator, Region Ill NRC Senior Resident Inspector, LaSalle County Station Illinois Emergency Management Agency Division of Nuclear Safety

ATTACHMENT 1 Response to Request for Additional Information By letter to the U. S. Nuclear Regulatory Commission (NRC) dated January 29, 2015, Exelon Generation Company, LLC (EGC) submitted relief request (RR) 13R-14 for LaSalle County Station (LSCS), Units 1 and 2 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15030A175). RR 13R-1 4 is intended to apply American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (ASME Code), Code Case N-702, "Alternative Requirements for Boiling Water Reactor (BWR) Nozzle Inner Radius and Nozzle-to-Shell Welds," to reactor pressure vessel nozzles at LSCS. EGC supplemented RR 13R-1 4 with a letter dated June 8, 2015.

In an email dated June 30, 2015, the NRC provided a follow-up RAI related to its review of RR l3R-14.

NRC RAI-1 Follow-up Clarification The June 8, 2015, response to the NRC RAI provides proprietary and non-proprietary nozzle stress reports (Attachments 3 and 4) and probabilistic fracture mechanics (PFM) reports (Attachments 5 and 6) to support the January 29, 2015, relief request 13R-1 4. Attachments 5 and 6 do not mention the stress corrosion cracking (SCC) initiation time. The December 19, 2007 SE on BWRVIP-1 08, "Technical Basis for the Reduction of Inspection Requirements for the Boiling Water Reactor Nozzle-to-Vessel Shell Welds and Nozzle Blend Radii," states [on page 8], "The original BWRVIP-108 report assumed that the nozzle weld cladding is non-susceptible to SCC and applied a factor of 5 to the curve based on cast austenitic stainless steel weld data as the mean SCC initiation curve in the PFM analyses. Since this assumption was not justified, the staff requested that the BWR VIP use a mean curve without the factor of 5 in this evaluation. This change increased the P(FIE) for nozzle significantly." Since the December 19, 2007, SE on BWRVIP-108 is based on the PFM results using a mean SCC initiation curve without the factor of 5, please confirm that the PFM analyses of Attachments 5 and 6 are consistent with the December 19, 2007, SE approach regarding the SCC initiation time.

EGC Response The SCC initiation time used in the PFM reports (Attachments 5 and 6) of the EGC RAI response dated June 8, 2015, is 8.42E19

• This input is consistent with the NRC SE for BWRVIP-108 dated December 19, 2007.

The Structural Integrity Associates, Inc. Report confirming this response is provided in .

Page 1 of 1

ATTACHMENT 2 Structural Integrity Associates, Inc."

Report No. 1400187.401, Revision 0 Response to NRC RAI Regarding Stress Corrosion Cracking (SCC) Initiation Time 2 pages follow

C structural Integrity Associates, Inc.

5215 Neityer Ave.

Suite 210 San Jose, CA 95138-1025 Phone: 408978.8200 Fax: 4089784964 wwv struc nt corn wu@stfuchnt cern July 27, 2015 Report No. 1400187.40 LRO Quality rogram:

P Ms. JoAnn Shields LaSalle County Generating Station - Exelon Corporation 2601 North 21 Road Marseilles, Illinois 61341-9757

Subject:

Response to Nuclear Regulatory Committee (NRC) Request for Additional Information (RAL) Regarding Stress Corrosion Cracking (SCC) Initiation time.

I. Structural Integrity Calculation Package: Probability of Failure for LaSalle Unit 2 Ni Ao:zle-io-Shell-Welds and Nozzle Blend Radii Regions, Revision 2, SI File Number 1400 187.302.

2, Sakti, Evaluation of Proprietary EPRJ Report: BWR Vessel and internals Project, Technical Basis for the Reduction ofInspection Requfi-emenis for the Boiling Water Reactor no::le-to-17essel S/ic/I J EclLfs and Noz:Ie inner Radius IBJTRVIP-]08j. EPRI PROPRIETARY INFORMATION.

3. BWRVIP Report. "BWR Reactor Pressure Vessel Shell Weld Inspection Recommendations (BWRVIP-05): Electric Poer Research Institute TR-105697, September 1995. EPRI PROPRIETARY INFORMATION.

This letter is to response to Nuclear Regulatory Committee (NRC) Request for Additional Information (RAI) regarding Stress Corrosion Cracking (SCC) initiation time used in analyses for probability of failure for LaSalle Unit 2 NT nozzle-to--shell welds and nozzle blend radii regions [1]. The objective of this letter is to confirm that the approaches used in the analyses documented in Reference I are consistent with the approach approved in the Safety Evaluation (SE) report dated December 19, 2007 [21 in regard to SCC initiation time.

The SCC initiation time used by SI is 0.842 xI020cr'0 , per Reference 3 where or is the applied stress. and is used in calculating the probability of failure for LaSalle Unit 2 NI nozzle-to-shell-welds and nozzle blend radii regions documented in Reference I.

Tall-Free 877-474-7693 Akra0H Ae!n,1X Chote,NC ChaeTh 330-899-9753 512-533-9191 704-7-5554 423-553-1180 Clcago, L Dwyr, CO Sn D$eo,CA San Joxe, CA akCIege, PA Toronto, Canada 877-474-7693 303-792-0077 858-4554350 408418.8200 814454-7776 905429-981?

JoAnn Shields July 27, 2015 Report No, 1401187,401.R0 Page 2 of 2 If you need further information, please do not hesitate to contact Structural integrity Inc.

Prepared by: Verified by:

1I7f AiJ Jim Wu July 27, 2015 Wilson Wong July 27, 2015 Consultant Engineer Approved by:

Stan Tang July 27, 2015 Associate C structural Integrity Associates, Ir,c