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, LLC Eueg Catawba Nuclear Station PlTEnergy, 4800 Concord Road Carolinas York, SC 29745 May 3, 2012 10 CFR 50.55a U.S. Nuclear Regulatory Commission Attention:

Document Control Desk Washington, DC 20555-0001

Subject:

Duke Energy Carolinas, LLC (Duke Energy)Catawba Nuclear Station, Units 1 and 2 Docket Numbers 50-413 and 50-414 Proposed Alternative Request Number 11-CN-001 for the Third Ten-Year Inservice Inspection Interval Response to NRC Request for Additional Information (TAC Nos. ME7277 through ME7283)

Reference:

Letter from Duke Energy to NRC dated September 28, 2011 The reference letter requested relief associated with limited weld examinations performed during the Unit 1 End-of-Cycle (EOC) 17 Refueling Outage (RFO), the Unit 1 EOC 18 RFO, and the Unit 2 EOC 16 RFO. On March 13, 2012, Requests for Additional Information (RAIs) were electronically received from the NRC. The purpose of this letter is to formally respond to these RAIs. The enclosure to this letter contains Duke Energy's response.

The format of the response 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. Hamrick Interim Site Vice President Enclosure 40(7 www. duke-energy, com U.S. Nuclear Regulatory Commission Page 2 May 3, 2012 xc (with enclosure):

V.M. McCree Regional Administrator U.S. Nuclear Regulatory Commission

-Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, GA 30303-1257 G.A. Hutto, III NRC Senior Resident Inspector U.S. Nuclear Regulatory Commission Catawba Nuclear Station J.H. Thompson (addressee only)NRC Project Manager (Catawba Nuclear Station)U.S. Nuclear Regulatory Commission Mail Stop 0-8 G9A Washington, DC 20555-0001 Enclosure Duke Energy Corporation Catawba Nuclear Station, Units I and 2 Relief 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 of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, for Catawba 1 and 2. The RR is requested for the remainder of the Third 1O-Year Inservice Inspection (ISI) Interval for Catawba 1 and 2 (ending on July 15, 2014, and August 19, 2016 for Catawba 1 and 2 respectively), in which the licensee adopted the 1998 Edition, with the 2000 Addenda, 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 multiple ASME Code Examination Categories.

The ASME Code requires that 100 percent of the examination 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 achieving inspection of 100 percent of the ASME Code-required volumes or surface areas is impractical at Catawba 1 and 2.The regulation at 10 CFR 50.55a (g)(5)(iii) states that when licensees determine that conformance with ASME Code requirements is impractical at their facility, they shall submit information to support this determination.

The NRC staff will evaluate such requests based on impracticality, and may impose alternatives, giving due consideration to the burden imposed on the licensee.The NRC staff has reviewed the information provided by the licensee in RR-CN-001and finds that 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 the result of component geometry, were not associated with flaws in the component welds, and were acceptable without further evaluation.

The indications were dispositioned 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 attachments identify which system(s) would be impacted by a leak or failure. The enclosures to the subject 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 to Question #3.Duke Energy Corporation Catawba Nuclear Station, Units I and 2 Relief Request #11-CN-001, Request for Additional Information Enclosure

-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 Diagram Request Number Number Section (Copies Attached)Number 6.0 1NI11-9 Safety Injection (NI) Piping from Safety CN-1562-1.3 Injection Pumps 1A and 1B 9.0 ISGD-W261 Auxiliary Feedwater Steam Generator 1D CN-1592-1.1 (CA) Auxiliary Feedwater Nozzle to Transition Ring 10.0 1CA66-35 Auxiliary Feedwater Piping connecting to CN-1592-1.1 (CA) Steam Generator 1A Auxiliary Feedwater Nozzle 12.0 2NI70-4 Safety Injection (NI) Cold Leg "C" Piping CN-2562-1.3 connecting to Valve 2NI175 4. The components in these sections are described as constructed of stainless steel. Are any of the subject components described in these sections constructed of cast stainless steel?Duke Energy Response: No.5. The difficulty in obtaining volumetric coverage on several of the subject welds in these sections appears to be caused by use of fixed-angle probes with limited range available for scanning.

Provide a discussion on alternative examination methods and techniques that are qualified to ASME Code,Section XI, Appendix VIII (e.g., phase-array ultrasonic techniques (line scan or raster)), that cover many angles to be used to enhance the coverage of the subject welds described in these sections.Duke Energy Response: Use of manual or automated UT, phased array qualified under ASME Section Xi, Appendix VIII would not increase coverage due to the limitation created by the component configuration.

The use of any other technique available would incur the same physical scanning limitations.

Therefore, use of phased array or any other techniques, whether automated or manual, would obtain no additional coverage.Duke Energy Corporation Catawba Nuclear Station, Units I and 2 Relief Request #1 1-CN-001, Request for Additional Information Enclosure

-Page 3 of 4 For sections 4 and 5: 6. For the Heat Exchanger Head-to-Flange Weld #1 ELDHX-HD-FLG, Summary Number C1 .20.0003, it was noted that limitations were caused by the four physical scanning limitations, all located on the S2 head side. Describe in detail the four limitations that prevent 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 proximity to, and on one side of, the 9-1/2" diameter heat exchanger head-to- flange weld. The nozzle welds completely covered the adjacent base material on the Surface 2 head up to the toe of the weld for a total length of 15 inches. The total weld length, including the limited inspection areas, is 30 inches.The NRC question requests that a response be provided for both sections 4 and 5. However, question 6 is specific to section 4, so a response for section 5 has not been provided.Duke Energy Corporation Catawba Nuclear Station, Units 1 and 2 Relief Request #1 1-CN-001, Request for Additional Information Enclosure

-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~yA 8 tl I i v l4 IL1x1ýT=ZD-a=A* _A-TrAC, ATA-i 20ACI. 1A"'I~'T'khtLWhI-h

-,ja -om am -V MINII A fls mll IAYISI -Wsat a".st KIW O CN- 1562-01 83 [ED~14 A (ýJ.-I S14 k7V o CA CONDITION 2 CA CONDITION I L I a3 0 gggg~a WhIN~AI~0.1.15AflAO FLOW l 03015 OF SAM 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

• i It + i J I 1 1 12 1 13 1 14 ,,i 10WO NO 4rrno159-1 1 19 h I t h-1 Li f-~' 25C~-SI, ~~aEi I L --.JI 1424 C3=4-I I-+-i -c.[4- -A --÷ i _<-4 IL~ ~C9-~ -+-9i:2: f= !-v C3:)-. H aNO~---~- Q w-@-C I -mm;- h-C;a

• Ha -~r P, 6wS CL4 : S*G i I-IH I I-~z C:"-c 5-- I~1A= C~OCO n&c P) --t .- T,- p Ptr I; R -! 1 a CA- .10-AAAAuL2t

'iHIu GA CONDITION 4 GA CONDITION I 0ý9 _PVý4Ft 1 1 1. 1 1 1CTLý m ,1 Fo W 10011,01OF UXKI01 FEOAE II~flf4H11AIiiil~t

'7H'~FIMTE4 II CAI-r-w _______________

A ITM I -I ý-- I I 3 4 b a .8, ...'11 .ý 0 --, & -1 2 1 b I 10 1 II 2u. 1 I A OR=M-140 EO aen CNOOA PEI 2 a 1 SM 1 o I I I -- "- .53 1 54 1 A.An.aOa.u.

an A n.m A a Af-Ala- -Al.-J9--AA.~~A ~ AMAW.~-6:o~~C=10A-CIE=a i 1..KAV~A~ CN-3NK2-I 3 I K H~i:L N[A.NaI0~ -~;r3 T~sro~ 1*K CATPns~~t3A AX3CLC7NAT~

~'T1aVr7 ~fZa~LL~ ~ o 1.50.I at a E1~m ~Cal K odoA M w~fa"i-n.KI~Le~I i -.D Itt Y., t .... \GA CONDITONZ SI DAAAA n~aAO CONDITION I ft ~ ~ ~ ~ i I t A AS A AMAASMQIIA MJ= 5CtEO r NCIAI IT 2 II I allt I 4 kOSIIA AAAA~t MA A AN CN-25627-I13 2 1 3 1 a I-I I c Ij i j, i