ML13179A116

Request for Relief ANO1-ISI-022 from ASME Code Examination Requirements for Pressure-Retaining Welds in Piping; Fourth 10-Year Inservice Inspection Interval

ML13179A116
Person / Time
Site:	Arkansas Nuclear
Issue date:	07/24/2013
From:	Markley M Plant Licensing Branch IV
To:	Entergy Operations
Kalyanam N
References
TAC ME9148
Download: ML13179A116 (8)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 July 24, 2013 Vice President, Operations Arkansas Nuclear One Entergy Operations, Inc.

1448 S.R. 333 Russellville, AR 72802

SUBJECT:

ARKANSAS NUCLEAR ONE, UNIT 1 - REQUEST FOR RELIEF AN01-ISI-022 FROM ASME CODE, SECTION XI VOLUMETRIC EXAMINATION REQUIREMENTS FOR THE FOURTH 10-YEAR INSERVICE INSPECTION INTERVAL, FIRST PERIOD (TAC NO. ME9148)

Dear Sir or Madam:

By letter dated July 25,2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12207A594), as supplemented by letter dated May 16,2013 (ADAMS Accession No. ML13136A142), Entergy Operations, Inc. (Entergy, the licensee),

submitted Request for Relief AN01-ISI-022 from certain requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, at Arkansas Nuclear One (ANO), Unit 1. The licensee's request is applicable to the fourth 10-year inservice inspection (lSI) interval, first period, which began on May 31,2008, and ended on May 30,2011.

During ultrasonic examination of the pressure retaining welds in piping,22-060 and 22-064, greater than 90 percent coverage of the required examination volume could not be obtained as required by Code Case N-460. In several locations, it was determined that the examinations were impractical due to interference or geometry. As required by paragraph 50.55a(g)(5)(iv) of Title 10 of the Code of Federal Regulations (10 CFR), Entergy has submitted the basis for the determination of impracticality to the U.S. Nuclear Regulatory Commission (NRC) for review and approval within 12 months after the expiration of the 120-month inspection interval.

The NRC staff has reviewed the licensee's submittals and concludes that ASME Code examination coverage requirements are impractical for Welds22-064 and 22-060. The staff concludes 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), and is in compliance with the requirements of 10 CFR 50.55a with the granting of this relief. Therefore, the NRC staff grants relief for the subject examinations of the components contained in Request for Relief AN01-ISI-022 for the ANO, Unit 1, fourth 10-year lSI interval, first period.

The NRC staff has further determined that granting AN01-ISI-022 in accordance with 10 CFR 50.55a(g)(6)(i) 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.

- 2 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 Inservice Inspector.

If you have any questions, please contact the Project Manager, Kaly Kalyanam at 301-415-1480 or via e-mail at Kaly.Kalyanam@nrc.gov.

Sincerely,

~. L&~~ -4?e>V Michael T. Markley, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-313

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. AN01-ISI-022 FOR THE FIRST PERIOD OF THE FOURTH 10-YEAR INSERVICE INSPECTION INTERVAL ENTERGY OPERATIONS, INC.

ARKANSAS NUCLEAR ONE. UNIT 1 DOCKET NO. 50-313

1.0 INTRODUCTION

By letter dated July 25, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12207A594) as supplemented by letter dated May 16, 2013 (ADAMS Accession No. ML13136A142), Entergy Operations, Inc. (Entergy, the licensee),

requested that the U.S. Nuclear Regulatory Commission (NRC) grant Request for Relief AN01-ISI-022 from the essentially 100 percent weld examination coverage requirements specified in American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, 2001 Edition through the 2003 Addenda for two Class 1 welds in the makeup and purification system at Arkansas Nuclear One (ANO), Unit 1. The licensee's request is applicable to the fourth 10-year inservice inspection (lSI) interval, first period, which began on May 31, 2008, and ended on May 30, 2011.

Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(6)(i),

the licensee requested relief for lSI items on the basis that the code requirement is impractical.

2.0 REGULATORY EVALUATION

The licensee has requested relief from ASME Code requirements for the inspection of two Class 1 piping welds pursuant to 10 CFR 50.55a(g)(6)(i).

Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 components (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 lSI interval and subsequent lSI intervals Enclosure

-2 comply with the requirements in the latest edition and addenda of Section XI of the ASME Code, 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.

The regulations in 10 CFR 50.55a{g){5)(iii) state, in part, that licensees may determine that conformance with certain code requirements is impractical and that the licensee shall notify the Commission and submit information in support of the determination.

The regulations in 10 CFR 50.55a{g){6)(i) state, 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.

Based on the above, and subject to the following technical evaluation, the NRC staff concludes that regulatory authority exists for the licensee to request and the Commission to grant the relief requested by the licensee.

3.0 TECHNICAL EVALUATION

3.1 The Licensee's Relief Request Welds Covered Under Relief Request The two welds covered under AN01-ISI-022 are 2.5 inch nominal pipe size (NPS 2.5),

Inspection Category B-J welds. Under the risk-informed lSI program the welds are designated Risk Category RA. Both welds are considered Item Number R1.11, "Elements Subject to Thermal Fatigue," and weld 22-060 is also considered Item Number R1.16, "Elements Subject to Intergranular or Transgranular Stress Corrosion Cracking (IGSCC or TGSCC)."

Table 1: Welds Covered Under Relief Request AN01-ISI-022

, WeldlD Inspection Item Cumulative Component Description Number Coverage Obtained (Percent)22-064 B9.11, (R1.11) 87.8 ASTM SA-312, TP-316 Pipe-to- ASTM A-403, WP 316 Elbow Weld using ER316L Weld metal 22-060 B9.11, (R1.11/16) 50 ASTM SA-312, TP-316 Pipe-to-ASTM A-182, F-316 Valve Weld using ER316 and E316 Weld Metals 3.2 ASME Code Requirements Both welds are covered under ASME Code,Section XI, Table IWB-2500-1, Examination Category B-J, "Pressure Retaining Welds in Piping," Item Number 89.11.

- 3 Item Number 89.11 requires a volumetric examination of circumferential piping welds nominal pipe size 4 inches or larger, as depicted in Figures IW8-2500-8. Item 89.11 requires that "essentially 100 percent" of the weld be examined. ASME Code Case N-460 clarifies that "essentially 100 percent" allows a reduction in Class 1 examination coverage, provided the reduction is less than 10%.

The subject welds are NPS 2.5, but are still volumetrically examined as part of the risk-informed lSI program. The licensee was authorized to use a risk-informed lSI program in the safety evaluation dated June 2,2010 (ADAMS Accession No. ML101170127). The authorized risk informed lSI program utilizing Code Case N-716 which is based, in large part, on NRC approved Electric Power Research Institute (EPRI) TR-112657 (ADAMS Accession No. ML013470102).

3.3 Applicable Code Edition The Code of record for the fourth 10-year inspection interval at ANO-1 is the 2001 Edition of the ASME Code,Section XI through the 2003 Addenda. ANO-1's fourth 10-year lSI interval began on May 31,2008, and is ongoing.

3.4 Relief Requested Pursuant to 10 CFR 50.55a(g)(6)(i), the licensee requests relief from the requirements of ASME Code,Section XI, Table IW8-2500-1. Examination Category 8-J, which requires that the inspections cover essentially 100 percent of the weld, as permitted by ASME Code Case N-460, when performing volumetric examinations of welds22-064 and 22-060.

3.5 8asis for Relief (as stated by the licensee)

During ultrasonic examination of the piping welds listed in Table 1, greater than 90%

coverage of the required examination volume could not be obtained as required by Code Case N-460.

Access for axial scanning was limited on the upstream side of weld 22-064 at top dead center due to interference of a weld-o-Iet and on the downstream side of weld 22-064 at bottom dead center due to interference of an adjacent pipe run.

Access was limited to single side on weld 22-060 due to pipe-to-valve configuration for both axial and circumferential scans. See Table 1 [letter dated July 25, 2012] for additional information.

Class 1 piping and components are often designed with welded joints such as nozzle-to-pipe, pipe-to-valve and pipe-to-pump which can physically obstruct a large portion of the required examination volume. For the weld 22-060, the examination was performed after the 10 CFR 50.55a mandatory implementation date for Appendix VIII of Section XI, and Code coverage percentages, provided, reflect what is currently allowed by qualified Appendix VIII techniques.

Appendix VIII qualified PDI [Performance Demonstration Initiative] procedures have demonstrated that sound beams may potentially be attenuated and

- 4 distorted when required to pass through austenitic weld metal. Still, the PDI qualified methods employ the best available technology for maximizing examination coverage of these types of welds. Examination was extended to the far side of the weld to the extent permitted by geometry, but this portion of the examination is not included in the reported coverage for welds examined under PDI and Appendix VIII rules.

Entergy has used the best available and EPRI approved techniques to examine the subject piping welds. To improve upon these examination coverage percentages, modification and/or replacement of the component would be required. Consistent with the ASME [Code] Section XI sampling approach, examination of the subject welds, when combined with examinations that have been performed on other welds within the same Examination Category, is adequate to detect generic degradation, if it existed, therefore demonstrating an acceptable level of integrity.

3.6 Proposed Alternative Examinations (as stated by the licensee)

No alternative testing is proposed at this time. Entergy has examined the subject welds to the extent practical and will continue to perform pressure testing and VT -2 visual examination in accordance with ASME Section XI requirements to compliment the limited examination coverage after each refueling outage.

3.7 NRC Staff Evaluation The ASME Code requires essentially 100 percent volumetric and surface examinations for selected ASME Code,Section XI, Table IWB-2500-1, Examination Category B-J pressure retaining welds in piping. However, complete volumetric examinations are restricted by materials and weld configurations. These conditions preclude the licensee from obtaining full volumetric examinations. The welds would require design modifications to obtain essentially 100 percent coverage. Imposition of the ASME Code-required volumetric examinations would therefore impose a burden on the licensee.

Welds22-064 and 22-060 are a Class 1, NPS 2.5, schedule 160 (=0.375 inch thick), welds in the makeup and purification system. Both welds are located in the high-pressure injection piping to reactor coolant system piping on the discharge side of "An reactor coolant pump. Both welds were ultrasonically inspected with an ASME Code,Section IX, Appendix VIII qualified procedure using a combination of 45, 60 and 70 degree shear waves.

Weld 22-064 joins an austenitic elbow to austenitic pipe with austenitic weld metal. The inspection of weld 22-064 obtained 83.8 percent coverage for circumferential flaws, 91.9 percent coverage for axial flaws, with a cumulative coverage of 87.8 percent. Coverage was limited due to a weld-o-Iet and an adjacent run of piping that obstructed access to the weld.

The NRC staff has determined that the coverage obtained was sufficient to have found large circumferential cracks if they had been present. While it is possible for axial cracks to be hidden in the region obstructed by nearby piping, there is no operating experience showing leaks in austenitic welds in the makeup and purification system in operating power plants. While a lack of previous cracking does not preclude future degradation, this lack of operating experience,

- 5 coupled with the coverage obtained, provides reasonable assurance of the system's structural integrity.

Weld 22-060 joins an austenitic pipe to austenitic valve using austenitic weld metal. The licensee was able to obtain 50 percent coverage (for both axial and circumferential flaws) for the inspection of weld 22-060. Coverage was limited due to the configuration of the valve, only permitting inspections from the pipe side of the weld. The NRC staff has determined that the coverage obtained was sufficient to have found circumferential and axial cracks on the pipe side of the weld with reduced reliability for the heat affected zone on the valve side of the weld had they been present. As with Weld 22-064, there is no operating experience showing leaks in austenitic welds in the makeup and purification system in operating power plants.

The NRC staff concludes that the examinations performed and the lack of cracking found in makeup and purification system piping in other nuclear power plants over decades provide reasonable assurance of structural integrity of the subject components. The licensee has shown that it is impractical to meet the ASME Code-required volumetric examination coverage for the subject welds due to the design geometry of the welds.

4.0 CONCLUSION

The NRC staff has reviewed the licensee's submittals and concludes that ASME Code examination coverage requirements are impractical for Welds22-064 and 22-060. The staff concludes 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), and is in compliance with the requirements of 10 CFR 50.55a with the granting of these reliefs. Therefore, the NRC staff grants relief for the subject examinations of the components contained in AN01-ISI-022 for the fourth lSI interval at ANO, Unit 1. The staff has further determined that granting AN01-ISI-022 in accordance with 10 CFR 50.55a(g)(6)(i) 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.

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 Inservice Inspector.

Principal Contributor: J. Cumblidge Date: July 24, 2013

-2 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 Inservice Inspector.

If you have any questions, please contact the Project Manager, Kaly Kalyanam at 301-415-1480 or via e-mail at Kaly.Kalyanam@nrc.gov.

Sincerely,

/ra! (BSingal for)

Michael T. Markley, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-313

Enclosure:

Safety Evaluation cc w/encl: Distribution via ListServ DISTRIBUTION:

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DATE 6/26/13 7/24/13 OFFICIAL RECORD COpy