ML14328A249

Proposed Relief Request 13-MN-003

ML14328A249
Person / Time
Site:	Mcguire
Issue date:	11/26/2014
From:	Robert Pascarelli Plant Licensing Branch II
To:	Capps S Duke Energy Carolinas
Miller G
References
13-MN-003, TAC MF3477
Download: ML14328A249 (8)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 November 26, 2014 Mr. Steven D. Capps Vice President McGuire Nuclear Station Duke Energy Carolinas, LLC 12700 Hagers Ferry Road Huntersville, NC 28078 SUBJI;CT: MCGUIRE NUCLEAR STATION, UNITS 1 AND 2- PROPOSED RELIEF REQUEST 13-MN-003 (TAG NO. MF3477)

Dear Mr. Capps:

By letter dated February 6, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14055A402), as supplemented by letter dated July 29, 2014 (ADAMS Accession No. ML14224A011 ), Duke Energy Carolinas, LLC (the licensee) submitted RR 13-MN-003, to the U.S. Nuclear Regulatory Commission (NRC) a request for relief from the "Essentially 100%" volumetric coverage requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), S,ection XI for the third 10-year In service *Inspection (lSI) Program for McGuire Nuclear Station, Unit No. 2 (MNS2).

The NRC staff has reviewed the subject request and concludes, as set forth in the eoclosed safety evaluation, the NRC staff has determined that granting relief 1~-MN-003 pursuant to 10 CFR 50.55a(g)(5)(iii) is authorized by law and will not endanger life or property, or the common defense and security, and is otherwise in the public interest given due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.

Furthermore, the NRC staff concluded that the examinations performed to the extent practical provide reasonable assurance of structural integrity of the subject components. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(6)(i). Therefore, the NRC staff grants relief for the subject examinations of the components contained in 13-MN-003 at McGuire Nuclear Station, Unit 2, for the third 10-Year lSI inspection interval which ended on July 15, 2014.

All other ASME Code,Section XI, requirements, for which relief was not specifically requested and authorized herein by the NRC staff, remain applicable, including the third party review by the Authorized Nuclear In-service Inspector.

S.D. Capps If you have any questions, please contact the Project Manager, G. Edward Miller at 301-415-2481 or via e-mail at ed.miller@nrc.gov.

Sincerely, Robert J. Pascarelli, Chief Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-370

Enclosure:

Safety Evaluation cc w/encl: Distribution via ListServ

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST NO. 13-MN-002 DUKE ENERGY CAROLINAS, LLC MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 DOCKET NOS. 50-369 AND 50-370

1.0 INTRODUCTION

By letter dated February 6, 2014, and amended by letter dated July 29, 2014, (Agencywide Documents Access and Management System (ADAMS) Accession Numbers ML14055A402 and ML14224A011 respectively), Duke Energy Carolinas, LLC, (the licensee), submitted a request to the U.S. Nuclear Regulatory Commission (NRC) for relief from the "Essentially 100%"

volumetric coverage requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI for the third 10-year lnservice Inspection (lSI)

Program for McGuire Nuclear Station, Unit 2 (MNS2).

Specifically, pursuant to Title 10 of the Code of Federal Regulations (1 0 CFR) 50.55a(g)(5)(iii),

the licensee requested relief and to use alternative requirements for in-service inspection items on the basis that the code requirement is impractical due to access limitations caused by design for two welds in the Chemical and Volume Control System.

2.0 REGULATORY EVALUATION

The licensee has requested relief from ASME Code requirements pursuant to 10 CFR 50.55a(g)(5)(iii).

Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 co~ponents (including supports) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code, which was incorporated by reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein.

10 CFR 50.55a(g)(5)(iii), states in, part that, that licensees may determine that conformance with certain ASME Code requirements is impractical and that the licensee shall notify the Commission and submit information in support of the determination. A Determination of Impracticality, in accordance with this section, must be based on the demonstrated limitations experience when attempting to comply with the code requirements during the inservice inspection interval for which the request is being submitted. Requests for relief made in accordance with this section must be submitted to the NRC no later than 12 months after the expiration of the initial 120-month inspection interval or subsequent 120-month inspection interval for which relief is sought.

• 10 CFR 50.55a(g)(6)(i), states that the Commission will evaluate determinations under paragraph (g)(5) of this section that code requirements are impractical. The Commission may grant such relief and may impose such alternative requirements as it determines is authorized by law .and will not endanger life or property or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.

3.0 TECHNICAL EVALUATION

3.1 Requested Relief The licensee is requesting relief from the "Essentially 100 Percent" volumetric coverage requirements for two welds in the Chemical and Volume Control System of MNS2. These welds are described in Table 1.

Examination Item Size Claimed WeldiD Category Number (in.) Coverage Component Description 2ELDHX-HD-FLG C-A C1.20 9.5 79.80% Excess Letdown Heat Exchanger Head to Flange Dissimilar Metal Weld 2RCHPSS-OUT-1 R-A R1.11 4.5 62.50% Reciprocating Charging and Pump Suction Stabilizer R1.16 Piping Nozzle to Flange Weld Weld 2ELDHX-HD-FLG is a head to flange weld. The head is constructed of SS-304 stainless steel, the flange is SA-1 05-11 ferritic steel with a 3/16" T.K. SS 304 stainless steel overlay (on the ID). The weld is made of American Iron and Steel Institute (AISI) Type 310 stainless steel filler metal and the SS-304 (head to flange overlay) portion* of the weld used A lSI Type 308 filler metal.

• Weld 2RCHPSS-OUT-1 is between a forged stainless steel flange and nozzle, joined with ER308L filler.

Applicable ASME Code and RI-ISI Requirements The code of record for the Third 10-Year Inspection Interval at MNS2 is the ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through the 2000 Addenda.

The volumetric inspection coverage requirements for Weld 2ELDHX-HD-FLG are described in IWC-2500, Table IWC-2500-1, Examination Category C-A, Item Number C1.20 Figure IWC-2500-1 (a). ASME Code Section XI requires "essentially 100%" of the weld volume to be inspected.

Weld 2RCHPSS-OUT-1 is covered under the licensee risk-informed inservice inspection (RI-ISI) program. The NRC authorized the licensee's use of the RI-ISI Program for the Third 10-Year lSI Interval by letter dated June 12, 2002. (ML021480421 ). The volumetric inspection coverage requirements for Weld 2RCHPSS-OUT-1 in the RI-ISI program are described in WCAP-14572, Revision 1-NP-A, Supplement 2, Revision 1-NP-A, Table 4.1-1, Examination Category R-A, Item Number R1.11 and R1.16, using ASME Code Section XI Figure IWB-2500-8 (c).

The licensee's lnservice Inspection Plan allows the use of Code Case N-460 "Alternative Examination Coverage for Class 1 and Class 2 Welds", which requires greater than 90%

volumetric coverage of examination volume.

Duration of Proposed Alternative Relief Request 11-MN-03 covers the duration of the Third 10-Year lnservice Inspection Interval, which ended on July 15, 2014.

Basis For Relief UT of the welds 2ELDHX-HD-FLG and 2RCHPSS-OUT-1 were conducted using personnel, equipment, and procedures qualified in accordance with ASME Section XI, 1998 Edition with the 2000 Addenda. The licensee has examined the welds to the maximum extent possible utilizing approved examination techniques and equipment.

In addition to the above Code required volumetric examination, Reactor Building Normal Sump and Reactor Building Area Radiation Monitoring contribute to ensuring pressure boundary integrity by providing means to detect reactor coolant leakage and take prompt corrective actions.

For weld 2RCHPSS-OUT-1, system leakage tests are performed each inspection period in accordance with Table IWC-2500-1. Examination Category C-H requires a Visual, VT-2 examination to detect evidence of leakage. This test and VT -2 examination provides additional assurance of pressure boundary integrity. The Reciprocating Charging Pump Suction Stabilizer is located in the Reciprocating Charging Pump Room in the Auxiliary Building. The Reciprocating Charging Pump Room is part of Operator Rounds conducted once per shift.

Proposed Alternative Examinations None

3.2 Staff Evaluation The licensee has requested relief from the "essentially 100%" volumetric coverage requirements described in ASME Code Section XI and their RI-ISI program for two welds. However, the design configurations of the subject welds limit access for volumetric inspection. In order to effectively increase the examination coverage to meet ASME Code requirements, the welds would require design modifications. This would place a burden on the licensee.

Weld 2ELDHX-HD-FLG is a head to flange weld. The head is constructed of stainless steel, the flange is constructed of ferritic steel with a 3/16" stainless steel overlay on the ID. The weld is made of Type 310 stainless steel and the head to flange overlay portion of the weld used type 308 filler metal. While this is a dissimilar metal weld, the weld is a stainless steel alloy, not a nickel alloy, and is thus not considered highly susceptible to stress corrosion cracking. The licensee obtained volumetric inspection coverage of 79.8%. The entire ID was caved in the axial scans for circumferential flaws and the weld root area was covered by the circumferential

• scans for axial flaws. Additionally, the weld is normally .isolated. The weld is typically exposed to 100-120° F and 35-45 psi g. During startup, the maximum temperature seen just downstream of the Excess Letdown Heat Exchanger is approximately 165° F and the maximum pr~ssure seen is approximately 90 psig. Based on the resistant materials, the low operating temperatures and pressures, and the coverage obtained, there is reasonable assurance of structural integrity and leak tightness for weld 2ELDHX-HD-FLG.

Weld 2RCHPSS-OUT-1 joins a forged stainless steel nozzle to a forged stainless steel flange using stainless steel weld metal. The licensee obtained volumetric inspection coverage of 62.5 percent. The coverage included 50 percent of the ID surface for axial 'scans for circumferential flaws and 100 percent of the ID surface for circumferential scans for axial flaws. This weld typically exposed to approximately 85-95° F and 35-40 psig. Based on the resistant materials, the low operating temperatures and pressures, and the coverage obtained, there is reasonable assurance of structural integrity and leak tightness for weld 2RCHPSS-OUT-1.

In addition to the volumetric examinations, the licensee conducts the normal VT-2 examinations for signs of leakage during each outage. Finally, the licensee monitors the Reactor Building Sump and the Reactor Building Area Radiation levels. While these methods do not ensure leak tightness, they do contribute to component integrity by providing means to detect possible future leakage and allow prompt corrective actions, if it should occur.

The licensee has shown that it would be a burden to meet the ASME Code-required 100 percent volumetric examination coverage for the subject welds due to their design. Based on the volumetric coverage obtained for the two welds, the resistant material, and the low operating temperatures and pressures the NRC staff concludes that there is reasonable assurance of structural integrity of the subject components. Relief request 13-MN-003 thus meets the requirements for relief for impracticality described in 10 CFR 50.55a(g)(6)(i).

4.0 CONCLUSION

As set forth above, the NRC staff has determined that granting relief 13-MN-003 pursuant to 10 CFR 50.55a(g)(5)(iii) is authorized by law and will not endanger life or property, or the common defense and security, and is otherwise in the public interest given due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.

Furthermore, the NRC staff concluded that the examinations performed to the extent practical provide reasonable assurance of structural integrity of the subject components. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(6}(i). Therefore, the NRC staff grants relief for

• the subject examinations of the components contained in 13-MN-003 at McGuire Nuclear Station, Unit 2, for the third 10-Year lSI inspection interval which ended on July 15, 2014.

All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in the subject requests for relief remain applicable, including third-party review by the Authorized Nuclear lnservice Inspector.

Principal Contributors: S. Cumblidge, NRR Date: November 26 ' 2014

ML14328A249 *SE input OFFICE NRR/DORLILPL2-1 /PM NRRIDORL/LPL2-1 /LA NRRIDE/EPNBA/BC NRR/DORL/LPL2-1 /BC NAME GEMiller SFigueroa DAiley* RPascarelli DATE 11/25/14 11/25/14 11/10/14 11/26)14