ML13133A114

Request for Additional Information, Relief Request 12-MN-004 Regarding Examination Coverage

ML13133A114
Person / Time
Site:	McGuire
Issue date:	05/22/2013
From:	James Kim Plant Licensing Branch II
To:	Capps S Duke Energy Carolinas
Kim J, NRR/DORL/LPL2-1, 415-4125
References
TAC MF0508, TAC MF0513, TAC MF0514, 12-MN-004
Download: ML13133A114 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 22, 2013 Mr. Steven D. Capps Vice President McGuire Nuclear Station Duke Energy Carolinas, LLC 12700 Hagers Ferry Road Huntersville, NC 28078 SUB~IECT: REQUEST FOR ADDITIONAL INFORMATION - MCGUIRE NUCLEAR STATION, UNIT 1, RELIEF REQUEST 12-MN-004 REGARDING EXAMINATION COVERAGE (TAC NOS. MF0508, MF0513 AND MF0514)

Dear Mr. Capps:

By application dated November 29,2012, Duke Energy (the licensee) requested relief from the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) for McGuire Nuclear Station, Unit 1. Relief Request 12-MN-004 covers ten welds for which the licensee was not able to achieve essentially 1OO-percent examination coverage because of materials and geometrical limitations. These welds were required to be examined in accordance with the Inservice Inspection (lSI) Plan for McGuire, Unit 1, Third 10-Year Inservice Inspection Interval.

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the licensee's submittal and determined that additional information is needed in order to complete our review. The enclosed document describes this request for additional information (RAI). A response to this RAI is requested to be provided by June 28, 2013.

Sincerely,

(~

James Kim, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-369

Enclosure:

RAI cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST 12-MN-004 REGARDING EXAMINATION COVERAGE MCGUIRE NUCLEAR STATION, UNIT 1 By letter dated November 29,2012 (Agencywide Documents Access and Management System (ADAMS) at Accession Number ML12355A149), Duke Energy (the licensee) requested relief from the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) for McGuire Nuclear Station, Unit 1. Relief Request 12-MN-004 covers ten welds for which the licensee was not able to achieve essentially 100-percent examination coverage because of materials and geometrical limitations. These welds were required to be examined in accordance with the Inservice Inspection (lSI) Plan for McGuire, Unit 1, Third 10-Year Inservice Inspection Interval. To complete its review, the Nuclear Regulatory Commission (NRC) staff requests the following additional information.

1. For the axial scan, confirm that the single-sided examination was performed for welds 1NV1F7908, 1NC1F-1493, 1NC1F-1613, 1NC1F-1615, 1N1231-1, 1NVP888-1, and

'I NV1 FW53-27. For the axial scan, confirm that the double-sided examination was performed for weld 1WL1F3063. For the circumferential scan, confirm that the single-sided examination was performed for welds 1NV1 F7908, 1NC1F-1493, 1NC1 F-1613, 1NC1F-1615, 1NVP888-1 and 1NV1 FW53-27. For the circumferential scan, confirm that the double-sided examination was performed for welds 1N1231-1 and 1WL1 F3063.

2. Section 2.3 of the relief request states that the applicable code requirement for weld 1NV1 F7908 is Table IWC-2500-1, Examination Category C-F-1, Item Number C5.20, Figure IWC-2500-7(a), and 100% volume coverage of Examination Volume C-D-E-F.

Section 9.3 of the relief request states that the applicable code requirement for weld 1WL1F3063 is Table IWC-2500-1, Examination Category C-F-1, Item Number C5.21, Figure IWC-2500-7(a),

and 100% volume coverage of Examination Volume C-D-E-F.

Sections 2.3 and 9.3 did not mention the surface examination and the licensee did not mention the surface examination in other subsections within Sections 2.0 and 9.0. However, Table IWC-2500-1 ofthe 1998 edition of the ASME Code,Section XI, requires surface and volumetric examinations to be performed for Item Numbers C5.20 and C5.21.

(a) Discuss whether the surface examination was performed on these two welds. If yes, discuss the examination results. If not, justify.

(b) Sections 2.0 and 9.0 did not mention a supplemental examination for these two welds, but was performed on other welds. Discuss why a supplemental examination was not performed on these two welds.

3. Welds 1NI231-1, 1NVP888-1, 1NV1FW53-27, and 1RCHP-IN are ASME Class 2 components and their nominal pipe size (NPS) is less than 4 inches. They should be examined in accordance with Figure IWC-2500-7(a). However, under the "Applicable Code Requirement" section of these

-2 welds, these welds were classified as Examination Category R-A, Item R 1.16 which would be examined in accordance with Figure IWB-2500-8(c} which is applicable for ASME Class 1 piping with a NPS of 4 inches and greater. Explain why Figure IWB-2500-8(c} is applicable to these four ASME Class 2 welds.

4. For some welds such as 1NC1F-1493, the licensee stated in Section 3.7 of the relief request that " ... Reactor Building Normal Sump monitoring and other leakage detection systems provide additional assurance that, in the event that leakage did occur through this weld, it would be detected and proper action taken ... " For other welds such as 1NV1 F7908, the licensee stated in Section 2.7 of the relief request that " ...visual observations performed during operator rounds provide additional assurance that in the event leakage did occur through this weld, it would be detected and proper action taken ..."

(a) Discuss the "other" leakage detection systems. Discuss whether and how the applicable Reactor Coolant System (RCS) leakage detection systems satisfy NRC Regulatory Guide 1.45, Revision 1, "Guidance on Monitoring and Responding to Reactor Coolant System Leakage" in terms of reliability, redundancy and sensitivity.

(b) Discuss the minimum leak rate that can be detected by the RCS leakage detection systems and any technical specification limits and administrative limits on the leakage from the subject five welds to which the operator will adhere.

(c) Discuss how soon the operator will be notified when leakage is detected.

(d) Discuss why the operator cannot visually examine welds 1NC1F-1493, 1NC1F-1613,

'I NC1 F-1615, 1NI231-1, 1NV'I FW53-27, and 1WL 1F3063 during his rounds (the welds are inaccessible for visual examination because they are located inside the containment?).

(e) Discuss why the RCS leakage detection systems cannot be used to detect potential leakage from welds 'I NV1 F7908, 1NVP888-1 and 'I RCHP-IN.

(f) Discuss whether the operator is required by procedure(s) to specifically visually examine welds 1NV1 F7908, 1NVP888-1 and 1RCH P-I N during his rounds. If no procedure is written for this task, discuss how reliable is the operator's visually examination of these welds during his rounds.

(g) Discuss how often the operator conducts his rounds for this task.

5. For welds 1NI231-1, 1NVP888-1, and 1NV1FW53-27, Westinghouse report, WCAP-14572, Revision 1-NP-A, 'Westinghouse Owners Group Application of Risk-Informed Methods to Piping Inservice Inspection Topical Report," Table 4.1-1 identifies intergranular stress corrosion cracking (IGSCC) as apotential degradation mechanism. For welds 1NC1F-1493, 1NC1F-1613, and 1NC1F-1615, WCAP report identifies thermal fatigue as a potential degradation mechanism. For weld 1RCHP-IN, the WCAP report identifies IGSCC and thermal fatigue as potential degradation mechanisms. The licensee did not identify the degradation mechanism for welds 1NV1 F7908 and 1WL1F3063.

(a) Discuss the potential degradation mechanism for welds 1NV1 F7908 and 1WL1F3063.

(b) Discuss whether actions have been taken to mitigate these degradation mechanisms, considering the operating parameters (e.g., pressures and temperatures), operating conditions (e.g., stagnant fluid, mechanical vibrations, thermal transients, thermal stratifications, and corrosive environment), and applied pipe stresses (are the stresses approaching the allowable stresses?).

-3 (c) If no actions have been taken to mitigate the potential degradation mechanism, discuss how the structural integrity of these five welds can be reasonably ensured in light of the deficiency in examination coverage.

(d) Discuss whether all the subject welds in the relief request will be examined in future lSI intervals as a way of monitoring their structural integrity.

6. Section 11.4 of the relief request stated that the radiographic testing performed on weld 1RCHP-IN during preservice inspection recorded a 0.042-inch tungsten inclusion which was accepted under the ASME Code,Section III, 1989 edition through the 2004 addenda and ASME Code,Section XI, 1998 edition through 2000 Addenda. It appears that the radiographic testing for weld 1RCHP-IN during the third lSI was preservice inspection.

(a) Discuss whether subsequent examinations have been performed on the weld to monitor the potential growth of the indication in the third lSI interval. If no, discuss whether the weld will be examined in the future lSI intervals to monitor the potential growth. Justify if subsequent examinations will not be performed.

(b) Section 11.3 of the relief request included applicable code requirements from the preservice inspection and WCAP-14572. The preservice inspection requirements are different from the WCAP-14572 requirements. Clarify which requirements are applicable to weld 1RCHP-IN.

7. The relief request is related to the limited examination coverage for the subject welds because the licensee is not able to achieve essentially 100 percent coverage. However, the relief request does not provide the material specification of the subject welds. Discuss the material specification for welds 1NV1F7908, 1NC1F-1493, 1NC1F-1613, 1NC1F-1615, 1NI231-1, 1NVP888-1, 1NV1 FW53-27, 1RCHP-IN and 1WL1F3063 in the relief request. The licensee needs to identify, at a minimum, the weld material type such as carbon steel, low alloy steel, or austenitic stainless steel. If information is available, provide specific filler material specification such as ER308L.

" "" ML13133A114 *via email OFFICE NRR/LPL2-1/PM NRR/LPL2-1/LA NRR/LPL2-1/BC NRR/LPL2-1/PM NAME JKim SFigueroa (SF)* EBrown for RPascarelli JKim DATE 05/22/13 05/14/13 05/22/13 05/22/13