ML091210549

Request for Additional Information (RAI) Regarding Nuclear Energy Institute Topical Report Material Reliability Program (MRP) Technical Basis for Preemptive Weld Overlays for Alloy 82/182 Butt Welds in Pressurized Water Reactors (MRP-169)

ML091210549
Person / Time
Site:	Mcguire, McGuire, Nuclear Energy Institute
Issue date:	05/13/2009
From:	Jacqueline Thompson Plant Licensing Branch II
To:	Brandi Hamilton Duke Energy Carolinas
Thompson, J.H. NRR/DPR/PSPB 415-1119
References
MRP-169, TAC MD8005
Download: ML091210549 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 13, 2009 Mr. Bruce H. Hamilton Vice President McGuire Nuclear Station Duke Energy Carolinas, LLC 12700 Hagers Ferry Road Huntersville, NC 28078

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION (RAI) REGARDING NUCLEAR ENERGY INSTITUTE TOPICAL REPORT MATERIAL RELIABILITY PROGRAM (MRP) TECHNICAL BASIS FOR PREEMPTIVE WELD OVERLAYS FOR ALLOY 82/182 BUTT WELDS IN PRESSURIZED WATER REACTORS (MRP-169)

(TAC NO. MD8005)

Dear Mr. Hamilton:

By letter dated September 7, 2005, the Nuclear Energy Institute (NEI) submitted for the U.S.

Nuclear Regulatory Commission (NRC) staff's review Topical Report erR), "Material Reliability Program [MRP]: Technical Basis For Preemptive Weld Overlays For Alloy 82/182 Butt Welds in PWRs [Pressurized Water Reactors] (MRP-169)." The purpose of this letter is to request that Duke Energy Carolinas, LLC (Duke), provide certain information to assist the NRC staff in completion of the review of TR MRP-169. The NRC staff has determined that this additional information is needed to complete the review of this TR.

A positive outcome of the NRC staff's review of TR MRP-169 would provide the technical basis for the NRC staff to approve licensee requests for alternatives to the American Society of Mechanical Engineers, Boiler and Pressure Vessel Code requirements to use optimized weld overlays (OWOLs) to mitigate Alloy 82/182 dissimilar metal butt welds. Operating experience has demonstrated that these welds are susceptible to primary water stress corrosion cracking in reactor coolant system piping.

During an October 23,2008, public meeting to discuss TR MRP-169, the NRC staff stated that it would need to complete certain activities as part of its review of TR MRP-169, including independent weld residual stress and flaw growth analyses of the OWOL design. To perform its independent analyses, the NRC staff needs actual plant configuration and OWOL design data.

The purpose of these analyses is to verify the effectiveness of the OWOL.

By letters dated September 18 and October 9, 2008, Duke submitted a contingency relief request for the full structural weld overlay of the hot leg nozzles at McGuire Nuclear Station, Unit 1 (McGuire 1). Duke SUbsequently found that it did not need the relief request (RR) and withdrew the RR request because no indications were found in the hot-leg nozzles at McGuire 1. However, the NRC staff understands from discussions with Duke, that they had also completed a stress analysis and design calculations for other OWOLs. Providing the NRC staff with this stress analysis and these design calculations will support NRC staff review of TR MRP-169.

B. Hamilton -2 It is our understanding that Duke is providing the requested information to the NRC staff in support of the efforts of NEI regarding TR MRP-169 and that this information is not submitted with respect to any pending licensing action at McGuire. Please provide your response within 45 days of this letter.

Sincerely, Jon Thompson, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-369 and 50-370 Project No. 689

Enclosure:

Request for Additional Information cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION TOPICAL REPORT MATERIAL RELIABILITY PROGRAM (MRP): TECHNICAL BASIS FOR PREEMPTIVE WELD OVERLAYS FOR ALLOY 82/182 Bun WELDS IN PRESSURIZED WATER REACTORS (MRP-169)

NUCLEAR ENERGY INSTITUTE PROJECT NO. 689 By letter dated September 7,2005 (Agencywide Documents and Access Management System Accession No. ML052520325), the Nuclear Energy Institute submitted for the U.S. Nuclear Regulatory Commission (NRC) staff's review Topical Report (TR) "Material Reliability Program

[MRP]: Technical Basis For Preemptive Weld Overlays For Alloy 82/182 Butt Welds in PWRs

[Pressurized Water Reactors] (MRP-169)."

By letters dated September 18 and October 9,2008, Duke Energy Carolinas, LLC (Duke),

submitted a contingency relief request (RR) for the full structural weld overlay (FSWOL) of the hot-leg nozzles at McGuire Nuclear Station, Unit 1 (McGuire 1). Duke subsequently found that it did not need the RR and withdrew the RR because no indications were found in the hot-leg nozzles at McGuire 1. The NRC staff is requesting that the following information regarding these FSWOLs be provided by Duke in support of the NRC staff review of TR MRP-169:

1. Geometry of reactor vessel hot-leg nozzle, safe-end, and pipe, including cladding and buttering. This geometry should include bevel and weld land details.

2. Materials and material properties to be used (fUll stress-strain curves used in analysis if possible; yield and ultimate strengths for each material are needed at a minimum)

3. Sequencing of welding, cladding or buttering, and heat treatment of original Alloy 82/182 dissimilar butt welds and safe-ends, including assumed root pass grind-out and re-weld.

4. Geometry, material properties, locations, and process steps of repairs made, if any, in the Alloy 82/182 dissimilar metal weld, the adjacent nozzle, or safe end.

5. In-process stress relieving heat treatment parameters.

6. Weld overlay materials, including extent and thickness of stainless steel buffer layer if any.

7. Optimized weld overlay (OWOL) geometry (if unavailable at this time, provide recommended OWOL geometry for the NRC's initial analysis).

Enclosure

-2

8. FSWOl geometry. This geometry is needed to compare the stress analysis for the aWOL design.

9. Weld overlay pass direction and sequence (1 weld head vs. multiple weld heads, sequence of weld passes, and direction of the weld pass).

10. Weld pass energy input (voltage, current, arc efficiency, and weld pass speed).

11. Weld inter-pass cooling temperature.

12. Convective heat transfer coefficient used for outside diameter and inside diameter surfaces.

B. Hamilton -2 It is our understanding that Duke is providing the requested information to the NRC staff in support of the efforts of NEI regarding TR MRP-169 and that this information is not submitted with respect to any pending licensing action at McGuire. Please provide your response within 45 days of this letter.

Sincerely, IRA!

Jon Thompson, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-369 and 50-370 Project No. 689

Enclosure:

Request for Additional Information cc w/encl: Distribution via Listserv Distribution:

PUBLIC RidsNrrDorlLpl2-1 Resource LPL2-1 R/F ESullivan (hard copy)

RidsNrrLAMO'BrienResource RidsNrrPMTMenshaResource RidsNrrPMJThompsonResource RidsAcrsAcnw MailCTRResource RidsNrrDorlDprResource Rids OgcRpResource RidsRgn2MailCenter Resource RidsNrrPmdaResource Accession Number* ML091210549 OFFICE NRR/LPL2-1/PM NRR/LP2-1/LA NRR/LPL2-1 /BC NAME JThompson MO'Brien MWong (SRohrer for) (RMartin for)

DATE 4/27/2009 5/6/09 5/13/09 OFFICIAL RECORD COpy