CNS-17-061, Third Ten-Year Inservice Inspection Plan, Limited Volumetric Examinations Response to NRC Requests for Additional Information

Third Ten-Year Inservice Inspection Plan, Limited Volumetric Examinations Response to NRC Requests for Additional Information

ML17362A042
Person / Time
Site:	Catawba
Issue date:	12/21/2017
From:	Simril T Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CNS-17-061
Download: ML17362A042 (6)

Text

tf~DUKE 11 Tom Simril

~ ENERGY Vice President Catawba Nuclear Station Duke Energy CN01 VP I 4800 Concord Road York, SC 29745 o: 803.701.3340 f: 803.701.3221 tom.simril@duke-energy.com CNS-17-061 December 21, 2017 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001

Subject:

Duke Energy Carolinas, LLC (Duke Energy)

Catawba Nuclear Station, Unit 1 and 2 Docket Numbers 50-413 and 50-414 Relief Request # 17-CN-001 Third Ten-Year lnservice Inspection Plan, Limited Volumetric Examinations Response to NRG Requests for Additional Information

References:

1. Letter from Duke Energy to the NRG dated May 25, 2017, ADAMS Accession No. ML17150A305

2. Letter from the NRG to Duke Energy dated November 29, 2017, ADAMS Accession No. ML17335A097 Reference 1 was submitted for the Catawba Nuclear Station, Units 1 and 2, Relief Request for Third Ten-Year lnservice Inspection Plan, Limited Volumetric Examinations. Reference 2 transmitted Requests for Additional Information (RAls) from the NRG associated with the relief request.

The purpose of this letter is to formally respond to the RAI questions contained in the November 29, 2017, letter. The enclosure to this letter constitutes Duke Energy's response to the RAls.

The format of the enclosure is to re-state each RAI question, followed by its associated response.

There are no regulatory commitments contained in this letter or its enclosure.

If you have any questions concerning this material, please call Dustin Yang at (803) 701-3084.

Sincerely,

~O'rA~

Tom Simril Vice President, Catawba Nuclear Station

Enclosure:

Requests for Additional Information, Relief Request#17-CN-001 www.duke-energy.com

'C Document Control Desk Page 2 xc (with enclosure):

C. Haney Region II Administrator U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Avenue NE, Suite 1200 Atlanta, GA 30303-1257 J. D. Austin Senior Resident Inspector U.S. Nuclear Regulatory Commission Catawba Nuclear Station M. Mahoney (addressee only)

Project Manager U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mailstop 0-8B1A Rockville, MD 20852

REQUESTS FOR ADDITIONAL INFORMATION RELIEF REQUEST# 17-CN-001 THIRD TEN-YEAR INSERVICE INSPECTION PLAN LIMITED VOLUMETRIC EXAMINATIONS DUKE ENERGY CATAWBA NUCLEAR STATION, UNITS 1 AND 2 DOCKET NOS. 50-413 and 50-414 RAl-01 Provide wall thickness, operating pressure and temperature for the welds listed in Section 1.0 of to this relief request.

Catawba response:

The wall thickness, operating pressure and temperature for the welds listed in Section 1.0 are as follows:

Nozzle Operating Operating Weld No. Description Nominal Wall Pressure Temperature Thickness 1NC22-WN7 14" Pressurizer Surge Line 1.406" 2235 PSIG 614.9°F 12" Residual Heat Removal 1NC22-WN8 1.125" 2235 PSIG 614.9°F Line 1NC24-WN9 6" Safety Injection Line 0.718" 2235 PSIG 614.9°F 2NC11-WN7 14" Pressurizer Surge Line 1.406" 2235 PSIG 616.7°F 12" Residual Heat Removal 2NC11-WN8 1.125" 2235 PSIG 616.7°F Line 12" Residual Heat Removal 2NC13-WN9 1.125" 2235 PSIG 616:7°F Line RAl-02 In the third 10-year ISi interval, were any through-wall leaks identified in the subject Class 1 piping welds during system leakage test conducted in accordance with Examination Category B-P of Table IWB-2500-1?

Catawba response:

In the third 10-year ISi interval, no through-wall leaks were detected on the subject Class 1 piping welds during system leakage tests conducted in accordance with Examination Category 8-P of Table IWB-2500-1.

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REQUESTS FOR ADDITIONAL INFORMATION RELIEF REQUEST# 17-CN-001 THIRD TEN-YEAR INSERVICE INSPECTION PLAN LIMITED VOLUMETRIC EXAMINATIONS DUKE ENERGY CATAWBA NUCLEAR STATION, UNITS 1 AND 2 DOCKET NOS. 50-413 and 50-414 RAl-03 Was the UT procedure used for the inservice inspection (ISi) demonstrated on a plant-specific CASS mockup having deep flaws in the outer two thirds of volume of the pipe wall thickness?

Catawba response:

No. During the previous (second) inservice inspection interval, procedure demonstration using plant-specific CASS mockup having deep inner flaws in the inner one third of volume was attempted unsuccessfully. Subsequently, CNS requested and received relief for this demonstration in Relief Request 04-CN-001, Revision 1 (ADAMS Accession No. ML051230324). During the third inservice inspection interval, calibration was performed using a calibration block made of SA-351 CFBA centrifugally cast stainless steel with axially and circumferentially oriented side-drilled holes.

RAl-04 Given the inability to inspect the required volume C-0-E-F of Figure IW8-2500-8, the inability to qualify the UT procedure and personnel, and the limited coverage of the proposed volume (i.e.,

less than 50 percent coverage of the outer two thirds of volume), provide the cumulative usage factor based on the actual plant operating cycles for each Class 1 weld listed in this relief request to ensure the structural integrity of unexamined volume of the weld.

Catawba response:

Cumulative Usage Factors (CUF) associated with actual plant operating cycles are not available. However, bounding values of CUFs associated with the total number of design transient events over plant life are reported for each ASME Class 1 weld location below. All CUFs satisfy the acceptance limits of the ASME Section Ill NB-3600 Code with significant margin.

Weld No. Description/Location Max CUF Allowable 1NC22-WN7 14" Pressurizer Surge Line / 18 0.276 1.0 1NC22-WN8 12" Residual Heat Removal Line / 18 0.044 1.0 1NC24-WN9 6" Safety Injection Line/ 1A 0.016 1.0 2NC11-WN7 14" Pressurizer Surge Line/ 28 0.276 1.0 2NC11-WN8 12" Residual Heat Removal Line / 28 0.044 1.0 2NC13-WN9 12" Residual Heat Removal Line / 2C 0.044 1.0 Page 2 of 4

REQUESTS FOR ADDITIONAL INFORMATION RELIEF REQUEST# 17-CN-001 THIRD TEN-YEAR INSERVICE INSPECTION PLAN LIMITED VOLUMETRIC EXAMINATIONS DUKE ENERGY CATAWBA NUCLEAR STATION, UNITS 1 AND 2 DOCKET NOS. 50-413 and 50-414 RAl-05 NRG report, NUREG/CR-7122 "An Evaluation of Ultrasonic Phased Array Testing for Cast Austenitic Stainless Steel Pressurizer Surge Line Piping Welds" published in March 2012 (ADAMS Accession No. ML12087A061) documents the latest NRG guidance for an effective inspection of CASS components from the OD. Furthermore, ASME Code Case N-824 "Ultrasonic Examination of Cast Austenitic Piping Welds From the Outside Surface Section XI, Division 1" that has been incorporated by reference in 10 CFR 50.55a (by Federal Register Notice 82 FR 32934, dated July 18, 2017 (which became effective on July 18, 2017)) with conditions provides improved requirements for inspecting CASS until a performance demonstration qualification and testing for CASS to be developed.

Discuss whether the licensee has considered implementing ASME Code Case N-824 or using NRG NUREG/CR-7122 guidance to improve the effectiveness of its CASS inspection in the next interval.

Catawba response:

The licensee intends to use ASME Code Case N-824 for future examination of these CASS welds in the next inspection interval.

RAl-06 The NRG staff notes that in Section 3.5 of this relief request, the licensee requested relief from 1-2220 of Appendix I while in Section 4.1, the licensee discussed impracticality of compliance associated with 111-2200 of Appendix Ill.

For consistency and clarification, identify the specific paragraph in the ASME Code,Section XI for which the relief is sought, and discuss impracticality associated with that specific paragraph in the ASME Code,Section XI.

• Catawba response:

ASME Section XI (1998/2000A), IWA-2232 requires that ultrasonic examinations shall be conducted in accordance with Mandatory Appendix I. Appendix I, 1-2220 (Welds in Piping) requires that "Ultrasonic examination procedures, equipment, and personnel used to detect and size flaws in piping welds shall be qualified by performance demonstration in accordance with Appendix VIII and no other 1-2000 requirements apply ." Appendix VIII, Vlll-3100 (Qualification Test Requirements) specifies qualification test requirements of performance demonstration for ultrasonic examination systems. Vlll-311 O (Detection) subsection (c) reads, "For piping welds whose requirements are in course of preparation, the requirements of Appendix Ill, as supplemented by Table 1-2000-1, shall be met." Since, the requirements for cast austenitic piping welds are in the course of Page 3 of 4

REQUESTS FOR ADDITIONAL INFORMATION RELIEF REQUEST# 17-CN-001 THIRD TEN-YEAR INSERVICE INSPECTION PLAN LIMITED VOLUMETRIC EXAMINATIONS DUKE ENERGY CATAWBA NUCLEAR STATION, UNITS 1 AND 2 DOCKET NOS. 50-413 and 50-414 preparation per Table Vlll-3110-1,and applicable per Vlll-311 O (a), the requirements of Appendix Ill, as supplemented by Table 1-2000-1, apply.

Therefore, relief was requested from the overall requirement to perform a procedure demonstration in accordance with Mandatory Appendix I, 1-2220. However, the specifics of the impracticality of compliance is detailed in Mandatory Appendix Ill due to the relationship of the Mandatory Appendices as described above.

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