TMI-14-136, Response to Request for Additional Information - Submittal of Relief Request RR-14-01 Concerning Alternative Root Mean Square (Rms) Depth Sizing Requirements

Response to Request for Additional Information - Submittal of Relief Request RR-14-01 Concerning Alternative Root Mean Square (Rms) Depth Sizing Requirements

ML14328A189
Person / Time
Site:	Three Mile Island
Issue date:	11/19/2014
From:	Jim Barstow Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TMI-14-136
Download: ML14328A189 (5)

Text

10 CFR 50.55a TMl-14-136 November 19, 2014 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Three Mile Island Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-50 N RC Docket No. 50-289

Subject:

Response to Request for Additional Information - Submittal of Relief Request RR-14-01 Concerning Alternative Root Mean Square (RMS) Depth Sizing Requirements

References:

1) Letter from J. Barstow (Exelon Generation Company, LLC) to U.S.

Nuclear Regulatory Commission, "Submittal of Relief Request RR-14-01 Concerning Alternative Root Mean Square (RMS) Depth Sizing Requirements," dated September 19, 2014

2) Letter from J. Lamb (U.S. Nuclear Regulatory Commission) to M. Pacilio (Exelon Generation Company, LLC), "Three Mile Island, Unit 1 - Request for Additional Information Regarding Relief Request RR-14-01 Concerning Alternative Root Mean Square Depth Sizing Requirements (TAC No. MF4873)," dated November 14, 2014 In the Reference 1 letter, Exelon Generation Company, LLC (Exelon) submitted a relief request associated with the fourth lnservice Inspection (ISi) interval for Three Mile Island Nuclear Station (TMI), Unit 1. TMI, Unit 1 proposed alternative Root Mean Square (RMS) depth sizing requirements in accordance with 10 CFR 50.55a(g)(5)(iii). In the Reference 2 letter, the U.S. Nuclear Regulatory Commission requested additional information. Attached is our response to this request.

There are no commitments in this letter.

Response to Request for Additional Information Relief Request RR-14-01 November 19, 2014 Page2 If you have any questions concerning this letter, please contact Tom Loomis at (610) 765-5510.

Respectfully, Jam

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Director - Licensing & Regulatory Affairs Exelon Generation Company, LLC

Attachment:

Response to Request for Additional Information cc: Regional Administrator, Region I, USNRC USNRC Senior Resident Inspector, TMI USNRC Project Manager, [TMI]

ATTACHMENT Response to Request for Additional Information

Response to Request for Additional Information Page 1 By letter dated September 19, 2014 (Agency Wide Document Access and Management System (ADAMS) Accession No. ML14262A002), the Exelon Generation Company, LLC (the licensee) submitted Relief Request RR-14-01 requesting the use of alternate root mean square (RMS) error criteria for sizing flaws that are greater than the requirements of American Society of Mechanical Engineers (ASME) Code Case N-695, "Qualification Requirements for Dissimilar Metal Piping Welds," (N-695) at Three Mile Island Nuclear Station, Unit 1.

The U.S. Nuclear Regulatory Commission staff requests that the licensee provide additional information to support RR-14-01 from the RMS depth sizing requirements of ASME Code and ASME Code Case N-695.

Question:

What are the thickness of Core Flood Nozzles A and B and their associated safe ends?

Response

Figure 1: Dimensions of Core Flood Nozzle and Safe-End The dimensions of both the "A" and "B" Core Flood Nozzles are shown in Figure 1.

Question:

Please describe the inner diameter surface conditions of the weld onlays for the core flood nozzle-to-safe end welds (e.g., machined, ground smooth, as-welded, etc.).

Response

The "A" and "B" Core Flood Nozzle Weld onlays are machined surfaces.

Response to Request for Additional Information Page 2 Question:

Figure 1, "Core Flood 11 8 11 Nozzle to Safe-End Weld (RCT0001 RC00098MWELD)," shows that the weld onlay is made of Alloy 82. Please confirm if the onlay is Alloy 82.

Response

Due to issues encountered during the planned Alloy 600 mitigation activities on the "8" Core Flood Nozzle, Alloy 82 was used instead of the Alloy 52M material originally planned for use. The final "8" Core Flood Nozzle weld onlay used Alloy 82 material.