ML12125A297

Catawba Nuclear Station, Units 1 and 2 - Proposed Alternative Request Number 11-CN-001 for the Third Ten-Year Inservice Inspection Interval Response to NRC Request for Additional Information

ML12125A297
Person / Time
Site:	Catawba
Issue date:	05/03/2012
From:	Hamrick G T Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
11-CN-001, TAC ME7277, TAC ME7283
Download: ML12125A297 (9)

Text

Duke DUKE ENERGY CAROLINAS, LLCEueg Catawba Nuclear StationPlTEnergy, 4800 Concord RoadCarolinas York, SC 29745May 3, 2012 10 CFR 50.55aU.S. Nuclear Regulatory CommissionAttention: Document Control DeskWashington, DC 20555-0001Subject: Duke Energy Carolinas, LLC (Duke Energy)Catawba Nuclear Station, Units 1 and 2Docket Numbers 50-413 and 50-414Proposed Alternative Request Number 11-CN-001 for the Third Ten-YearInservice Inspection IntervalResponse to NRC Request for Additional Information(TAC Nos. ME7277 through ME7283)Reference: Letter from Duke Energy to NRC dated September 28, 2011The reference letter requested relief associated with limited weld examinations performedduring the Unit 1 End-of-Cycle (EOC) 17 Refueling Outage (RFO), the Unit 1 EOC 18 RFO, andthe Unit 2 EOC 16 RFO. On March 13, 2012, Requests for Additional Information (RAIs) wereelectronically received from the NRC. The purpose of this letter is to formally respond to theseRAIs. The enclosure to this letter contains Duke Energy's response. The format of theresponse is to restate each RAI question, followed by the response.This submittal document contains no regulatory commitments.If there are any questions or if additional information is needed, please contact L.J. Rudy at(803) 701-3084.Very truly yours,George T. HamrickInterim Site Vice PresidentEnclosure40(7www. duke-energy, com U.S. Nuclear Regulatory CommissionPage 2May 3, 2012xc (with enclosure):V.M. McCreeRegional AdministratorU.S. Nuclear Regulatory Commission -Region IIMarquis One Tower245 Peachtree Center Ave., NE Suite 1200Atlanta, GA 30303-1257G.A. Hutto, IIINRC Senior Resident InspectorU.S. Nuclear Regulatory CommissionCatawba Nuclear StationJ.H. Thompson (addressee only)NRC Project Manager (Catawba Nuclear Station)U.S. Nuclear Regulatory CommissionMail Stop 0-8 G9AWashington, DC 20555-0001

Enclosure

Duke Energy CorporationCatawba Nuclear Station, Units I and 2Relief Request #1 1-CN-001, Request for Additional Information NRC Request for Additional Information:In the subject RR, the licensee seeks relief from the requirements of the American Society ofMechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, forCatawba 1 and 2. The RR is requested for the remainder of the Third 1O-Year InserviceInspection (ISI) Interval for Catawba 1 and 2 (ending on July 15, 2014, and August 19, 2016 forCatawba 1 and 2 respectively), in which the licensee adopted the 1998 Edition, with the 2000Addenda, of Section XI of the ASME Code as the code of record for Catawba 1 and 2.In accordance with Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a(g)(5)(iii), the licensee has submitted the subject RR for relief for limited examinations in multipleASME Code Examination Categories. The ASME Code requires that 100 percent of theexamination volumes, or surface areas, described in ASME Code,Section XI, Tables IWB-2500-1, and IWC 2500-1 be performed during each interval. The licensee stated that achievinginspection of 100 percent of the ASME Code-required volumes or surface areas is impractical atCatawba 1 and 2.The regulation at 10 CFR 50.55a (g)(5)(iii) states that when licensees determine thatconformance with ASME Code requirements is impractical at their facility, they shall submitinformation to support this determination. The NRC staff will evaluate such requests based onimpracticality, and may impose alternatives, giving due consideration to the burden imposed onthe licensee.The NRC staff has reviewed the information provided by the licensee in RR-CN-001and findsthat the following additional information is needed to complete its review.For sections 2 through 12:1. Discuss any indications found during the examinations and their disposition.Duke Energy Response: All indications detected during the examinations were theresult of component geometry, were not associated withflaws in the component welds, and were acceptablewithout further evaluation. The indications weredispositioned using procedure guidance of probe skewing,use of higher angles and indication plotting.For sections 6, 9, 10 and 12:2. To determine the level of safety significance for each of the welds and/or attachmentsidentify which system(s) would be impacted by a leak or failure. The enclosures to thesubject RR provide this information for some of the welds and attachments, but not all.Duke Energy Response: The requested information is provided in the response toQuestion #3.Duke Energy CorporationCatawba Nuclear Station, Units I and 2Relief Request #11-CN-001, Request for Additional InformationEnclosure -Page 2 of 4

3. Provide a table or listing for each weld that lists the location and the systems.Duke Energy Response:This information is provided in the following table.Relief Weld ID System Location Flow DiagramRequest Number NumberSection (Copies Attached)Number6.0 1NI11-9 Safety Injection (NI) Piping from Safety CN-1562-1.3Injection Pumps 1A and1B9.0 ISGD-W261 Auxiliary Feedwater Steam Generator 1D CN-1592-1.1(CA) Auxiliary FeedwaterNozzle to Transition Ring10.0 1CA66-35 Auxiliary Feedwater Piping connecting to CN-1592-1.1(CA) Steam Generator 1AAuxiliary FeedwaterNozzle12.0 2NI70-4 Safety Injection (NI) Cold Leg "C" Piping CN-2562-1.3connecting to Valve2NI1754. The components in these sections are described as constructed of stainless steel. Areany of the subject components described in these sections constructed of cast stainlesssteel?Duke Energy Response:No.5. The difficulty in obtaining volumetric coverage on several of the subject welds in thesesections appears to be caused by use of fixed-angle probes with limited range availablefor scanning. Provide a discussion on alternative examination methods and techniquesthat are qualified to ASME Code,Section XI, Appendix VIII (e.g., phase-array ultrasonictechniques (line scan or raster)), that cover many angles to be used to enhance thecoverage of the subject welds described in these sections.Duke Energy Response:Use of manual or automated UT, phased array qualifiedunder ASME Section Xi, Appendix VIII would not increasecoverage due to the limitation created by the componentconfiguration. The use of any other technique availablewould incur the same physical scanning limitations.Therefore, use of phased array or any other techniques,whether automated or manual, would obtain no additionalcoverage.Duke Energy CorporationCatawba Nuclear Station, Units I and 2Relief Request #1 1-CN-001, Request for Additional InformationEnclosure -Page 3 of 4 For sections 4 and 5:6. For the Heat Exchanger Head-to-Flange Weld #1 ELDHX-HD-FLG, Summary NumberC1 .20.0003, it was noted that limitations were caused by the four physical scanninglimitations, all located on the S2 head side. Describe in detail the four limitations thatprevent performing the ASME Code-required examination.Duke Energy Response:The limitations encountered on this weld were two 2"diameter and two 34" diameter nozzles in close proximityto, and on one side of, the 9-1/2" diameter heat exchangerhead-to- flange weld. The nozzle welds completelycovered the adjacent base material on the Surface 2 headup to the toe of the weld for a total length of 15 inches. Thetotal weld length, including the limited inspection areas, is30 inches.The NRC question requests that a response be providedfor both sections 4 and 5. However, question 6 is specificto section 4, so a response for section 5 has not beenprovided.Duke Energy CorporationCatawba Nuclear Station, Units 1 and 2Relief Request #1 1-CN-001, Request for Additional InformationEnclosure -Page 4 of 4 I a 1 1. 1 11 1 11 1 il 1 1.I A I A I I In I A I IA I II I 12 I I~ I~yA8tl I i vl4IL1x1ýT=ZD-a=A* _A-TrAC,ATA-i 20ACI. 1A"'I~'T'khtLWhI-h -,ja -om am -VMINII A flsmll IAYISI -Wsat a".stKIW O CN- 1562-01 83 [ED~14 A (ýJ.-I S14 k7V oCA CONDITION 2CA CONDITION ILIa30gggg~a WhIN~AI~0.1.15AflAOFLOW l 03015 OFSAM limII) ST--* I A I A A I A I A I ' I A I .1 I IA I Sl IS I hA I CI

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