ML14070A008

Request for Alternative W3-ISI-023, ASME Code Case N-770-1 Successive Examinations, Third 10-Year Inservice Inspection Interval

ML14070A008
Person / Time
Site:	Waterford
Issue date:	03/26/2014
From:	Doug Broaddus Plant Licensing Branch IV
To:	Entergy Operations
Wang A
References
TAC MF2815
Download: ML14070A008 (10)

Text

. UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 March 26, 2014 Vice President, Operations Entergy Operations, Inc.

Waterford Steam Electric Station, Unit 3 17265 River Road Killona, LA 70057-3093

SUBJECT:

WATERFORD STEAM ELECTRIC STATION, UNIT 3- REQUEST FOR ALTERNATIVE W3-ISI-023, ASSOCIATED WITH WELD EXAMINATION COVERAGE REQUIREMENTS SPECIFIED IN ASME CODE CASE N-770-1 (TAC NO. MF2815)

Dear Sir or Madam:

By letter dated September 26, 2013, Entergy Operations, Inc. (the licensee), submitted a request to the U.S. Nuclear Regulatory Commission (NRC) for an alternative to the inspection coverage requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, for seven full-penetration welds at the Waterford Steam Electric Station, Unit 3 (Waterford 3).

Specifically, pursuant to paragraph 50.55a(a)(3)(ii) of Title 10 of the Code of Federal Regulations (1 0 CFR), the licensee proposed an alternative, W3-ISI-023, to the weld examination coverage requirements specified in ASME Code Case N-770-1, "Alternative Examination Requirements and Acceptance Standards for Class 1 PWR [Pressurized-Water Reactor] Piping and Vessel Nozzle Butt Welds Fabricated With UNS N06082 or UNS W86182 Weld Filler Material with or without Application of Listed Mitigation Activities," as conditioned by 10 CFR 50.55a(g)(6)(ii)(F). The basis for the alternative is that complying with the specified requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. As part of the alternative, the licensee requested authorization to use the proposed alternative for the subject welds for 54 months following the spring 2014 refueling outage examinations.

The NRC staff has reviewed the subject request and concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(a)(3)(ii).

The use of alternative W3-ISI-023 provides reasonable assurance of structural integrity and leak tightness, and that complying with the specified requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Accordingly, the NRC staff authorizes the use of alternative W3-ISI-023 at Waterford 3 until the scheduled refueling outage in" the fall of 2018; not to exceed 54 months at weld temperatures of 525 degrees Fahrenheit or greater, between completion of subject weld volumetric I

examinations. The authorization is invalid for a specific weld, if service-induced flaws are detected in the weld.

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

The NRC staff's safety evaluation is enclosed. If you have any questions, please contact the NRC project manager, Alan Wang, at 301-415-1445 or via e-mail at alan.wang@nrc.gov.

Sincerely, 97~ Douglas A Broaddus, Chief Plant Licensing IV-2 and Decommissioning Transition Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Doqket No. 50-382

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 ASME CODE CASE N-770-1 SUCCESSIVE EXAMINATION ALTERNATIVE W3-ISI-023 ENTERGY OPERATIONS, INC.

WATERFORD STEAM ELECTRIC STATION, UNIT 3 DOCKET NO. 50-382

1.0 INTRODUCTION

By letter dated September 26, 2013 (Reference 1), Entergy Operations, Inc. (the licensee),

proposed an alternative to the inspection coverage requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, for seven full-penetration welds at the Waterford Steam Electric Station, Unit 3 (Waterford 3).

Specifically, pursuant to paragraph 50.55a(a)(3)(ii) of Title 10 of the Code of Federal Regulations (10 CFR), the licensee submitted to the U.S. Nuclear Regulatory Commission (NRC) alternative W3-ISI-023 proposing an alternative to the weld examination coverage requirements specified in ASME Code Case N-770-1, "Alternative Examination Requirements and Acceptance Standards for Class 1 PWR [Pressurized-Water Reactor] Piping and Vessel Nozzle Butt Welds Fabricated With UNS N06082 or UNS W86182 Weld Filler Material with or without Application of Listed Mitigation Activities," as conditioned by 10 CFR 50.55a(g)(6)(ii)(F).

The basis for the alternative is that complying with the specified requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

The requirement pertains to volumetric examination of nickel-based Alloy 82/182 dissimilar metal butt welds (DMBW) associated with the suction and discharge piping of the reactor coolant pumps (RCPs) at Waterford 3. As part of the alternative, the licensee requested authorization to use the proposed alternative for the subject welds for 54 months following the spring 2014 refueling outage examinations.

2.0 REGULATORY EVALUATION

The regulations in 10 CFR 50.55a(g)(6)(ii) state that the Commission may require the licensee to follow an augmented inservice inspection (lSI) program for systems and components for which the Commission deems that added assurance of structural reliability is necessary.

The regulations in 10 CFR 50.55a(g)(6)(ii)(F) require that licensees of existing operating pressurized-water reactors implement the requirements of ASME Code Case N-770-1, subject to the conditions specified in paragraphs (g)(6)(ii)(F)(2) through (g)(6)(ii)(F)(1 0), by the first Enclosure

refueling outage after August 22, 2011. Specifically, paragraph 10 CFR 50.55a(g)(6)(ii)F)(4) states that "[t]he axial examination coverage requirements of -2500(c) may not be considered to be satisfied unless essentially 100 percent coverage is achieved."

However, 10 CFR 50.55a(a)(3) states, in part, that alternatives to the requirements of 10 CFR 50.55a(g) may be used when authorized by the NRC if the applicant demonstrates that: (i) the proposed alternatives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements would result in hardship or unusual difficulty

• without a compensating increase in the level of quality and safety.

Based on analysis ofthe regulatory requirements, the NRC staff concludes that regulatory authority exists to authorize the proposed alternative pursuant to 10 CFR 50.55a(a)(3)(ii).

3.0 TECHNICAL EVALUATION

3.1 Licensee's Request for Alternative Components Affected ASME Code C.lass 1 dissimilar nietal piping welds containing Alloy 82/182, ASME Code Case N-770-1, Inspection Item B, unmitigated butt weld at cold leg operating temperature.

The dissimilar metal piping welds covered by this alternative are identified below:

Component ID Component Description 07-002 30" Reactor Coolant Pump (RCP) 1A Inlet Elbow (CS) to Safe-end (Cast SS)08-014 30" RCP 1A Outlet Safe-end (Cast SS) to Pipe (CS)09-016 30" RCP 1B Inlet Elbow (CS) to Safe-end (Cast SS)10-002 30" RCP 1B Outlet Safe-end (Cast SS) to Pipe (CS)11-002 30" RCP 2A Inlet Elbow (CS) to Safe-end (Cast SS)13-016 30" RCP 28 Inlet Elbow (CS) to Safe~end (Cast SS)14-002 30" RCP 28 Outlet Safe-end (Cast SS) to Pipe (CS)

Code Requirements The Waterford 3 Code of Record for the third 10-year lSI interval ending on June 30, 2017, is

• the 2001 .Edition through the 2003 Addenda of the ASME Code,Section XI.

The subject welds are Classified as _Inspection Item "B", Unmitigated butt weld at Cold Leg operating temperature approximately 525 degrees Fahrenheit rF) and less than 580 OF for which visual and volumetric examinations are required.

The regulations in 10 CFR 50.55a(g)(6)(ii)(F)(1) require that, "[l]icensees of existing, operating pressurized-water reactors as of July 21, 2011 shall implement the requirements of ASME Code Case N-770-1, subject to the conditions specified in paragraphs (g)(6)(ii)(F)(2) through (g)(6)(ii)(F)(1 0) of this section, by the first refueling outage after August 22, 2011."

The ASME Code Case N-770-1 requires successive examination of all Inspection Item B welds, as defined in Table 1 of the Code Case; every second inspection period not to exceed seven years after the baseline examination is performed using Section XI, Appendix VIII requirements.

The regulations in 10 CFR 50.55a(g)(6)(ii)(F)(4) state that "[t]he axial examination coverage requirements of -2500(c) may not be considered to be satisfied unless essentially 100 percent coverage is achieved." ASME Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI, Division 1 ,"allows a reduction in coverage due to interference or geometry as long as the overall coverage is greater than 90 percent.

Licensee's Reason for Request The licensee anticipates the ultrasonic testing (UT) examination of the subject welds in the spring of 2014 will not obtain essentially 100 percent of the required examination volume for axial flaw detection, as s~en in the 2009 results. In order to obtain additional coverage, the licensee would need to modify or replace the components.

Licensee's Proposed Alternative and Basis for Use

The licensee proposes to ultrasonically examine the subject welds at Waterford 3 to the extent provided in Table 1 of alternative W3-ISI-023 (Reference 1), in lieu of the Code Case N-770-1 examination coverage requirements. If the examination coverage of a subject weld in Table 1 is less than the weld with the bounding examination coverage (RCP outlet weld 08-014), then an additional relief request would be provided to the N~C following completion of these examinations for the specific subject weld. The licensee requests that the duration of the proposed alternative for the subject welds be granted for 54 months following the spring 2014 examinations based on the following information.

The licensee cited information previously provided in its letters dated December 16, 2012 (Reference 2), and in letter dated December 4, 2012 (Reference 3), indicating that its analyses had concluded a postulated initial flaw that is 16.7 percent through wall would grow to the ASME Code-allowable flaw size of 75 percent through wall in approximately 54 months from the inspection. These documents further state that the largest undetected flaw that could exist due to the examination limitations is 10 percent through wall, providing a margin of 6.7 percent. The licensee also states that based on the scheduled inspections in spring 2014, and obtaining examination coverage equal to or better than the most limiting coverage obtained in the 2009 examinations, the crack growth analysis supports operation of Waterford 3 for 54 months at normal operating temperature from the spring 2014 exams. The licensee plans to perform the examinations again during the fall 2018 outage. '

The licensee cited the NRC staff's safety evaluation approving alternative W3-ISI-020 dated May 31, 2013 (Reference 4), concerning the examination of the subject welds. In the safety evaluation, the NRC staff determined that fulfilling the examination requirements for axial flaws

_./

is not possible using current available technology and procedures. The NRC staff also concluded that complying with the specified requirement would require modification or replacement of the components, which would constitute a hardship.

The licensee stated that the equipment, procedure, and personnel utilized for the 2009 examinations were qualified in accordance with the requirements of ASME Code,Section XI, Appendix VIII, as implemented through the Performance Demonstration Initiative (POl) program, employing the best available technology for maximizing examination coverage of these types of welds, and that the examinations performed on the subject areas demonstrated an acceptable level of integrity. Furtherm*ore, the licensee stated that current methods of examination to be used in the 2014 outage are essentially unchanged since 2009, and continue to be the best available technology. The licensee concludes that in order to improve upon this examination coverage percentage, modification and/or replacement of the component would be required.

3.2 NRC Staff Evaluation Primary water stress-corrosion cracking (PWSCC) ot'nickel-based pressure boundary materials is a safety concern: Operational experience has shown that PWSCC can occur as the result of the combination of susceptible material, corrosive environment and tensile stresses, resulting in leakage and the potential for loss of structural integrity. The subject DMBWs meet these

• conditions and thus may be susceptible to PWSCC. The examination requirements of ASME Code Case N-770-1, as conditioned by 10 CFR 50.55a(g)(6)(ii)(F), are intended to provide reasonable assurance of the structural integrity and leak tightness of DMBWs through nondestructive examination.

The subject DMBWs are PWSCC-susceptible Alloy 82/182 weld metal joining mill-clad carbon steel to cast austenitic stainless steel safe-ends. The subject welds are located on the 30-inch inside diameter of the RCP suction and discharge piping. As shown in Table 1 of alternative W3-ISI-023 (Reference 1), the licensee claims 100 percent coverage for detection of circumferential flaws in the nickel-based alloy materials; however, coverage for detection of axial flaws is shown to be between 65 percent and 84.5 percent.

The NRC staff issued a safety evaluation approving alternative W3-ISI-020 dated May 31, 2013 (Reference 4), concerning the baseline examination of the subject welds listed above. In the safety evaluation, the NRC staff determined that fulfilling the essentially 100 percent examination requirements for axial flaws was not possible using currently available technology and procedures. The NRC staff also concluded that complying with the specified requirement would require modification or replacement of the components, which would constitute a hardship. Furthermore, the safety evaluation concluded that alternative W3-ISI-020 provides reasonable assurance of structural integrity and leak tightness for 54 months until the scheduled refueling outage in the spring of 2014, and that complying with the specified requirement would

. result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. As basis for this determination, the NRC staff finds that a 16.7 percent through wall flaw can reasonably be detected within the bounding coverage using the methodology described in altern~tive W3-ISI-020 and any flaw less than this may not be detected. The staff performed conservative analyses as part of the safety evaluation, and concluded a postulated, undetected initial flaw that is 16.7 percent through wall and connected to the inside diameter of the weld would not grow beyond the ASME Code-allowable flaw size of 75 percent through wall

in approximately 54 months at operating temperature. A discussion of the circumferential scan coverage for axial flaws, flaw location, and detectability, including component drawings and flaw calculation assumptions, is contained in the licensee's supplemental response to an NRC staff request for additional information dated December 16, 2012 (Reference 2).

For this safety evaluation, the NRC staff notes there have been no changes or modifications made to the welds since the previous NRC evaluation of alternative W3-ISI-020. Therefore, the NRC staff continues to find that complying with the specified requirement would require modification or replacement of the components, which would constitute a hardship.

Similar to the previous safety evaluation, the NRC staff continues to find that a 16.7 percent through wall flaw connecting to the inside diameter of the weld can reasonably be detected within the bounding coverage using the methodology described in alternative W3-ISI-023. The NRC staff further reviewed the licensee's flaw analysis assumptions and previous NRC staff calculations, confirming that a postulated initial flaw that is 16.7 percent through wall would not grow beyond the ASME Code-allowable flaw size of 75 percent through wall in approximately r 54 months, at operating temperature, from the inspection date. The staff notes that the staff's and licensee's calculations were performed on hypothetical flaws growing at operating temperatures. The scope of ASME Code Case N-770-1 only includes welds at operating temperatures greater than or equal to 525 °F. Therefore, the staff concludes that these calculations conservatively support an inspection frequency of no greater than 54 months at 525 oF or greater..

The licensee' stated that lSI examination of the subject welds during the 2014 outage will utilize the same methodology as the 2009 examinations, and will comply with the requirements of ASME Code,Section XI, Appendix VIII, as implemented through the PDI program for encoded ultrasonic linear phased array technology. The NRC staff finds this to be an acceptable approach for this configuration. The licensee also stated that it will submit a new relief request for any spring 2014 outage examination coverage that is less than the bounding weld coverage, used for the flaw calculation as defined above for the subject welds. The NRC staff concludes thatthis is acceptable, as bounding coverage is a main assumption of the staff's and licensee's hypothetical flaw analysis calculations.

Given the identified hardship, the results from the NRC staff's and licensee's hypothetical flaw evaluation, and the licensee's best effort examination, the NRC staff finds that the methodology proposed in alternative W3-ISI-023 for modified coverage requirements provides reasonable assurance of structural integrity and leak tightness for the 54 month period following the spring 2014 examinations ofthe subject welds. This determination assumes bounding examination coverage is obtained during the spring 2014 examinations and no flaws are detected. Based on the above, the NRC staff concludes that complying with the requirements of 10 CFR 50.55a(g)(6)(ii)(F)(4) by performing an ASME Code-compliant examination of the subject RCP DMBWs would result in hardship without a compensating increase in the level of quality and safety.

4.0 CONCLUSION

As set forth above, the NRC-staff determines that authorizing the use of alternative W3-ISI-023 provides reasonable assurance of structural integrity and leak tightness, and that complying

with the specified requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(a)(3)(ii). Therefore, the NRC staff authorizes the use of alternative W3-ISI-023 at Waterford 3 until the scheduled refueling outage in the fall of 2018; not to exceed 54 months

• at weld temperatures of 525 oF or greater, between completion of subject weld volumetric examinations. The authorization is invalid for a specific weld, if service-induced flaws are detected in the weld.

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

5.0 REFERENCES

1. Pellegrin, B., Entergy Operations, Inc., letter to U.S. Nuclear Regulatory Commission, "Waterford 3 Request for Alternative W3-ISI-023, ASME Code Case N-770-1, Successive Examinations," dated September 26, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13270A041 ).

2. Rich, Jr., C. E., Entergy Operations, Inc., letter to U.S. Nuclear Regulatory Commission, "Waterford 3 Supplemental Response to an NRC Request for Additional Information associated with W3-ISI-020, ~equest for Alternative to ASME Code Case N-770-1 Baseline Examination [TAC No. ME9801]," dated December 16, 2012 (ADAMS Accession No. ML12352A172).

3. Pyle, S. L., Entergy Operations, Inc., letter to U.S. NuClear Regulatory Commission, "Revised Request for Alternative AN02-ISI-007, Code Case N-770-1 Baseline Examination," dated December 4, 2012 (ADAMS Accession ML12340A449).

4. Markley, M. T., U.S. Nuclear Regulatory Commission, letter to Entergy Operations, Inc.,

"Waterford Steam Electric Station, Unit 3 -Request For Alternative W3-ISI-020, ASME Code Case N-770-1 Baseline Examination (TACNo. ME9801)," dated May 31, 2013 (ADAMS Accession No. ML13128A129).

5. Mason, M. E., Entergy Operations, Inc., letter to U.S. Nuclear Regulatory Commission, "Waterford 3 Request for Alternative W3-ISI-020, ASME Code Case N-770-1 Baseline Examination Request for Alternative," dated October 16, 2012 (ADAMS Accession No. ML12296A241).

6. Mason, M. E., Entergy Operations, Inc., letter to U.S. Nuclear Regulatory Commission, "Waterford 3 Response to an NRC Request for Additional Information associated with W3-ISI-020, Request for Alternative to ASME Code Case N-770-1 Baseline Examination

[TAC No. ME9801)," dated November 15, 2012 (ADAMS Accession No. ML12324A170).

7. Kalyanam, N., U.S. Nuclear Regulatory Commission, "Waterford Steam Electric Station, Unit 3, Verbal Authorization of W3-ISI-020," dated December 18, 2012 (ADAMS Accession No. ML13085A125).

8. Pacific Northwest National Laboratory, Technical Letter Report, "Evaluation of Licensee's Alternative to 10 CFR 50.55a(g)(6)(ii)(F) for Limitations to Volumetric Examinations of Dissimilar Metal Welds, Entergy Operations, Inc., Arkansas Nuclear One, Unit 2," dated April 23, 2013 (ADAMS. Accession No. ML13113A218).

Principal Contributor: Kyle Hanley Date: March 26, 2014

ML14070A008 *via email dated OFFICE NRR/DORULPL4-2/PM NRR/DORULPL4-2/PM NRR/DORULPL4-2/LA NRR!DE/EPNB/BC NRR!DORULPL4-2/BC NAME MOrenak AWang JBurkhardt TLupold* DBroaddus DATE 03/11/14 03/11/14 3/11/14 02/27/14 03/26/14