ML20090F893
| ML20090F893 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 04/29/2020 |
| From: | Undine Shoop Plant Licensing Branch II |
| To: | Catherine Nolan Duke Energy Progress |
| Buckberg P | |
| References | |
| EPID L-2019-LLR-0072 | |
| Download: ML20090F893 (11) | |
Text
April 29, 2020 Mr. Christopher Nolan, Vice President Nuclear Regulatory Affairs, Policy &
Emergency Preparedness Duke Energy, LLC 526 South Church Street, EC-07C Charlotte, NC 28202
SUBJECT:
H. B. ROBINSON STEAM ELECTRIC PLANT UNIT NO. 2 - RELIEF REQUEST RA-19-0138 REGARDING PROPOSED ALTERNATIVE TO ASME CODE SECTION XI VOLUMETRIC EXAMINATION FREQUENCY REQUIREMENTS (EPID L-2019-LLR-0072)
Dear Mr. Nolan:
By letter dated July 23, 2019, as supplemented by letter dated March 4, 2020, Duke Energy Progress, LLC (the licensee) submitted a request to the U.S. Nuclear Regulatory Commission (NRC) for relief from certain requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, at the H. B. Robinson Steam Electric Plant (Robinson) Unit No. 2.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1), in relief request RA-19-0138, the licensee proposed an alternative volumetric examination schedule for the reactor vessel cold leg nozzle-to-safe end dissimilar metal butt welds on the basis that the alternative provides an acceptable level of quality and safety.
The NRC staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(1). Therefore, the NRC staff authorizes the use of relief request RA-19-0138 for up to, and including, the fall 2022 refueling outage (RO-33) in the fifth 10-year inservice inspection interval at Robinson Unit No. 2, which began on July 21, 2012, and is scheduled to end on February 18, 2023.
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 Inservice Inspector.
If you have any questions, please contact the Robinson Project Manager, Andrew Hon, at (301) 415-8480 or by email to Andrew.Hon@nrc.gov.
Sincerely,
/RA/
Undine Shoop, Chief Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-261
Enclosure:
Safety Evaluation cc: Listserv
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST RA-19-0138 REGARDING REACTOR VESSEL COLD LEG NOZZLE-TO-SAFE END DISSIMILAR METAL BUTT WELDS INSERVICE INSPECTION DUKE ENERGY PROGRESS, LLC H. B. ROBINSON STEAM ELECTRIC PLANT UNIT NO. 2 DOCKET NO. 50-261
1.0 INTRODUCTION
By letter dated July 23, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19204A082), as supplemented by letter dated March 4, 2020 (ADAMS Accession No. ML20064G768), Duke Energy Progress (the licensee) requested relief from certain requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI. In Relief Request RA-19-0138, the licensee proposed an alternative schedule for the volumetric inservice inspection (ISI) of the reactor vessel (RV) cold leg nozzle-to-safe end dissimilar metal (DM) butt welds at the H. B. Robinson Steam Electric Plant Unit No. 2 (Robinson).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1), the licensee proposed an alternative volumetric examination schedule for the RV cold leg nozzle-to-safe end DM butt welds on the basis that the alternative provides an acceptable level of quality and safety.
2.0 REGULATORY EVALUATION
Pursuant to 10 CFR 50.55a(g)(6)(ii)(F), all holders of operating licenses or combined licenses for pressurized-water reactors (PWRs) as of August 17, 2017, shall implement the requirements of ASME Code Case N-770-2, Alternative Examination Requirements and Acceptance Standards for Class 1 PWR Piping and Vessel Nozzle Butt Welds Fabricated With UNS N06082 or UNS W86182 Weld Filler Material With or Without Application of Listed Mitigation Activities,Section XI, instead of ASME Code Case N-770-1, subject to the conditions specified in paragraphs (g)(6)(ii)(F)(2) through (13) of 10 CFR 50.55a, by the first refueling outage after August 17, 2017.
Pursuant to 10 CFR 50.55a(z), alternatives to the requirements of paragraphs (b) through (h) of 10 CFR 50.55a, or portions thereof, may be used when authorized by the Director, Office of Nuclear Reactor Regulation. A proposed alternative must be submitted and authorized prior to implementation. The licensee must demonstrate that (1) the proposed alternative would provide an acceptable level of quality and safety or (2) compliance with the specified requirements of 10 CFR 50.55a would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
3.0 TECHNICAL EVALUATION
3.1 Background
By letter dated December 28, 2010 (ADAMS Accession No. ML103010406), the NRC reviewed the licensees propriety inspection results (ADAMS Accession No. ML083470836) and flaw evaluations (ADAMS Accession No. ML083470837), and found that the licensees determination for continued service was acceptable, because (a) the detected flaws in the RV hot and cold leg nozzle-to-safe end DM butt welds were verified to be subsurface flaws, which resulted from the welding fabrication process, and (b) the successive examinations of the RV hot and cold leg nozzle-to-safe end DM butt welds would monitor the existing fabrication flaws to ensure that the structural integrity of the affected nozzles is maintained.
3.2 Component Affected ASME Code Class 1 RV cold leg nozzle-to-safe end DM butt welds (i.e., loop A, loop B, and loop C) are affected. In accordance with Table 1 of ASME Code Case N-770-2, the licensee classified the RV cold leg nozzle-to-safe end DM butt welds as Inspection Item B.
The details provided by the licensee about the RV cold leg nozzle-to-safe end DM butt welds materials of construction and fabrication are summarized below:
The low alloy steel SA-336 nozzle forging was machined, and cladding consisting of 309 or 308 grade stainless steel filler metal was applied to the inside diameter (ID) surface of the nozzle.
A weld bevel on the nozzle was machined and buttered with Alloy 182 filler metal prior to fit-up and welding to SA-182 Type F316 stainless steel safe end by Alloy 82 filler metal.
Intermediate post-weld stress relief was applied after the nozzle cladding and safe end DM welding with a half hour hold time.
The cold and hot leg nozzles were welded to the RV shell, and the RV ID cladding was back-welded.
The completed RV with the nozzles and safe ends attached were heat treated for 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> at 1,150 degrees Fahrenheit (°F).
The licensee stated that the cold leg normal operating temperature is 547.6 °F, and normal operating pressure is 2,250 pounds per square inch absolute (psia). The ID of the cold leg nozzle-to-safe end DM butt welds is 27.50 inches with a wall thickness of 2.50 inches.
3.3
Applicable Code Edition and Addenda
The code of record for the fifth 10-year ISI interval is the 2007 Edition with 2008 Addenda of the ASME Code.
3.4 Duration of Relief Request The licensee submitted RA-19-0138 for the remainder of the fifth 10-year ISI interval up to, and including, the fall 2022 refueling outage (RO-33). The fifth 10-year ISI interval began on July 21, 2012, and is scheduled to end on February 18, 2023. The licensee stated that the fifth 10-year ISI interval has been extended from February 19, 2022, to February 18, 2023, in accordance with ASME Code,Section XI, IWA-2430.
3.5 ASME Code Requirement The ASME Code requirements applicable to this request originate in Section XI, Table IWB-2500-1. In accordance with 10 CFR 50.55a(g)(6)(ii)(F), the NRC has mandated an augmented inspection for the RV cold leg nozzle-to-safe end DM butt welds to implement the requirements of ASME Code Case N-770-2 with conditions specified in paragraphs (g)(6)(ii)(F)(2) through (13) of 10 CFR 50.55a.
In accordance with Table 1 of Code Case N-770-2, the RV cold leg nozzle-to-safe end DM butt welds classified as Inspection Item B are required to be volumetrically examined every second inspection period and not to exceed 7 calendar years.
3.6 Proposed Alternative The licensee proposed an alternative schedule for the volumetric ISI of the RV cold leg nozzle-to-safe end DM butt welds. The proposed schedule is to perform the volumetric examination of the RV cold leg nozzle-to-safe end DM butt welds in the fall 2022 refueling outage (RO-33) and not to exceed 9 calendar years from the prior ISI, which was completed in the September 2013 refueling outage (RO-28).
3.7 Basis for Use of Alternative The licensee stated that the proposed alternative allows for a coordinated schedule for the RV cold leg nozzle-to-safe end DM butt welds examination and the planned inspection of the RV shell welds and internals. By this coordination, removal of the RV lower internal (i.e., core barrel) assembly, which is required for access to the inside of the RV and the cold leg nozzles to perform these examinations, occurs once. The removal of the core barrel is considered a critical lift due to various reasons such as weight of the component, tight clearances involved, risks associated with equipment damage, and risk of personnel exposure to excessive radiation emitted by the assembly.
As discussed below, the licensees basis for the proposed alternative relied on (1) acceptable results from prior inspections of the RV nozzle-to-safe end DM welds, (2) a primary water stress corrosion cracking (PWSCC) flaw tolerance evaluation to demonstrate reasonable assurance of the structural integrity of the RV cold leg nozzle-to-safe end DM butt welds until the next proposed inspection, and (3) a fatigue flaw analysis by a cumulative usage factor (CUF) approach to demonstrate the growth of the existing subsurface flaws is unlikely.
3.7.1 Results of Prior ISI of RV Cold Leg Nozzle-to-Safe End DM Butt Welds The results of the licensees inspection activities on the RV cold leg nozzle-to-safe end DM butt welds during and after the October 2008 refueling outage (RO-25) are summarized as follows:
During the October 2008 refueling outage (RO-25), a qualified phased array ultrasonic test (PAUT) was performed on the RV cold leg nozzle-to-safe end DM butt welds from the ID surface in accordance with the Electric Power Research Institute (EPRI) Material Reliability Program (MRP)-139, Primary System Piping Butt Weld Inspection and Evaluation Guideline, and essentially 100 percent coverage of the required examination volume was achieved. The results from PAUT and supplemental eddy current testing confirmed the presence of two adjacent unacceptable subsurface axial flaws in the loop B RV cold leg nozzle-to-safe end DM butt weld. The flaws were treated as one subsurface flaw with a length of 1.5 inches and depth of 1.254 inches according to the ASME Code,Section XI, IWA-3300 proximity rule and were evaluated for continued service. The licensee did not find additional unacceptable flaws in the loops A, B, and C RV cold leg nozzle-to-safe end DM butt welds.
In the February 2012 refueling outage (RO-27), a reexamination of the loop B RV cold leg nozzle-to-safe end DM butt weld was performed in accordance with MRP-139, and the results were compared to the October 2008 refueling outage (RO-25) examination results. The licensee neither observed any changes to the characteristics of the existing subsurface axial flaws initially identified in the loop B RV cold leg nozzle-to-safe end DM butt weld in 2008 nor found additional unacceptable flaws in the loop B RV cold leg nozzle-to-safe end DM butt weld.
In the September 2013 refueling outage (RO-28), the licensee performed an augmented inspection of the loops A, B, and C RV cold leg nozzle-to-safe end DM butt welds in accordance with ASME Code Case N-770-1, as mandated by 10 CFR 50.55a(g)(6)(ii)(F) with conditions. For the loop B RV cold leg nozzle-to-safe end DM butt weld, the results from the September 2013 examination were compared to the refueling outages of October 2008 (RO-25) and February 2012 (RO-27) examinations. The licensee neither observed any changes to the characteristics of the existing subsurface axial flaws initially identified in the loop B RV cold leg nozzle-to-safe end DM butt weld in 2008 nor found additional unacceptable flaws in the loops A, B, and C RV cold leg nozzle-to-safe end DM butt weld.
Based on the above inspection results, the licensee concluded that the existing subsurface axial flaws in the loop B RV cold leg nozzle-to-safe end DM butt weld were dormant fabrication flaws, and no additional unacceptable flaws were present in the loops A, B, and C RV cold leg nozzle-to-safe end DM butt welds.
In addition, operating experience has shown that the RV cold leg nozzle-to-safe end DM butt welds, as compared to the RV hot leg nozzle-to-safe end DM butt welds, are less prone to PWSCC. The licensee stated that even though several unacceptable subsurface axial flaws were identified in three RV hot leg nozzle-to-safe end DM butt welds at Robinson, in October 2008, the subsequent examinations of the RV hot leg nozzle-to-safe end DM butt welds in February 2012, fall 2015, and fall 2018, showed no evidence of growth of these existing flaws and no presence of any other unacceptable flaws. Thus, based on Robinson operating experience, it is unlikely that the existing subsurface axial flaws in the loop B RV cold leg nozzle-to-safe end DM butt weld would grow.
3.7.2 PWSCC Flaw Tolerance Analyses Additional support for the acceptability of extending the examination interval for the loops A, B, and C RV cold leg nozzle-to-safe end DM butt welds is contained in the licensees plant-specific flaw tolerance analyses documented in Attachment 3 of RA-19-0138, Westinghouse LTR-SDA-18-016-NP, Revision 0, Technical Justification to Support the Extended Volumetric Examination Interval for H. B. Robinson Unit 2 Reactor Vessel Inlet Nozzle to Safe End Dissimilar Metal Welds. The licensee used industry guidance in EPRI MRP-287, Primary Water Stress Corrosion Cracking (PWSCC) Flaw Evaluation Guidance, for its flaw tolerance analyses.
The licensee stated that it performed plant-specific flaw tolerance analyses to demonstrate that postulated ID axial and circumferential flaws in the DM welds would not grow to the ASME Code allowable flaw size between the planned examinations (i.e., between the September 2013 refueling outage (RO-28) and the fall 2022 refueling outage (RO-33)). Based on Robinson operational data and anticipated refueling outages scheduled between September 2013 and fall 2022, the licensee projected the plant to operate at full power for 9 effective full power years between the proposed examinations. The flaw tolerance analyses were performed for the RV cold leg nozzle-to-safe end DM butt weld locations.
Potential PWSCC growth through the Alloy 82/182 weld material was evaluated using the normal operating temperature and pressure at the RV cold leg nozzle, the normal operating steady state piping loads, and weld residual stresses (WRSs). The licensee stated that the WRSs in the RV cold leg nozzle-to-safe end DM butt welds were computed using a plant-specific finite element analysis. In calculating WRS distributions, the licensee conservatively assumed 50 percent ID weld repairs at the time of construction. The finite element analysis modeling included a portion of the low alloy steel nozzle, the stainless steel safe end, a portion of the stainless steel piping, the DM weld attaching the nozzle to the safe end, and the stainless steel weld attaching the safe end to the piping.
In Figures 7-1 and 7-2 of Attachment 3 to RA-19-0138, the licensee provided the PWSCC crack growth curves through the thickness of the welds for both an axial and a circumferential flaw, respectively. The flaw tolerance analysis shows that the licensees calculated allowable axial ID surface-connected flaw (i.e., 0.285-inch deep or 11.4 percent through thickness of weld) and allowable circumferential ID surface-connected flaw (i.e., 0.985-inch deep or 39.4 percent through thickness of weld) would not grow to the allowable ASME Code flaw size limit of 75 percent in less than 9 years. Therefore, the licensee concluded that the results justify the requested extension of the next examinations as proposed in RA-19-0138. Given the capabilities of qualified PAUT and supplemental eddy current testing, the above allowable flaws would have been detected in the last inspection performed in the September 2013 refueling outage (RO-28).
3.7.3 Fatigue Flaw Analysis The licensee stated that the CUF of 0.0007 referenced in RA-19-0138 for the loop B RV cold leg nozzle-to-safe end DM butt weld location is documented in Combustion Engineering, Inc.
Report CENC-1111, Analytical Report for Carolina Power and Light Reactor Vessel, published in January 1967. The CUF was determined considering the design transients projected for the life of the plant as documented in CENC-1111.
Robinson has a Fatigue Monitoring Program, which tracks the cyclic loading and transients introduced by normal, test, and upset condition operations. Since the most recent inspection of the RV cold leg nozzle-to-safe end DM butt welds in 2013, Robinson has experienced a total of 40 transient conditions (i.e., plant heat-ups, cooldowns, loadings/un-loadings, and reactor trips).
This sum of actual transients is bounded by the design transients considered in CENC-1111 and is expected to remain bounded for the duration up to the next proposed volumetric examination in 2022. Therefore, it is unlikely that the existing subsurface flaws in the loop B RV cold leg nozzle-to-safe end DM butt weld would become ID surface-connected and subject to potential PWSCC growth.
3.8
NRC Staff Evaluation
The NRC staff has evaluated RA-19-0138 pursuant to 10 CFR 50.55a(z)(1). The staff focused on whether the alternative (i.e., accepting deferral of the volumetric examination for the RV cold leg nozzle-to-safe end DM butt welds from fall 2020 to fall 2022) provides an acceptable level of quality and safety. To reach a conclusion, the NRC staff performed independent flaw tolerance analyses and fatigue assessment for the bounding case of the Robinson RV cold leg nozzle-to-safe end DM butt welds.
3.8.1 NRC Staffs Fatigue Assessment The NRC staff assessed whether there exists a potential for the existing subsurface axial flaws in the loop B RV cold leg nozzle-to-safe end DM butt weld to grow and become ID surface-connected by the transient loading conditions during the proposed period between inspections (i.e., from September 2013 to fall 2022). The NRC staff verified that:
The licensees original design fatigue analyses determined a 0.0007 CUF at the loop B RV cold leg nozzle-to-safe end DM butt weld location. The NRC staff finds that this component location experiences a very low level of cyclic stresses and that the potential for the existing subsurface axial flaws to grow by cyclic stresses to become ID surface-connected is low.
The licensees Fatigue Monitoring Program reported that the loop B RV cold leg nozzle-to-safe end DM butt weld location has experienced a total of 40 transient occurrences from the heat-ups, cooldowns, loadings/un-loadings, and reactor trips since September 2013. The NRC staff finds that the accumulated plants actual transient occurrences reported by the licensee are bounded by the design-basis transient occurrences considered in the original design fatigue analysis and are expected to remain bounded even if they are combined with the postulated transient occurrences until fall 2022.
Therefore, the NRC staff finds that the impact of fatigue on the growth of the existing subsurface axial flaws to become ID surface-connected is significantly low. The NRC staff applied risk insights to assess safety implications of continued operation of the piping with the existing embedded fabrication axial flaws that could become ID surface-connected PWSCC as discussed below.
3.8.2 NRC Staffs Independent PWSCC Flaw Tolerance Analyses The NRC staff performed independent flaw tolerance analyses to evaluate whether the projected growth of assumed PWSCC surface-connected flaws in the loop B RV cold leg nozzle-to-safe end DM butt weld during the proposed period between inspections (i.e., from the September 2013 refueling outage (RO-28) to the fall 2022 refueling outage (RO-33)) would exceed the ASME Code allowable flaw size limit. The staff began by evaluating aspects of the licensees flaw tolerance analyses - specifically, the assumed initial defects, the characterization of WRSs, and the methodology for calculating PWSCC growth, for inclusion in the staffs independent analyses. Of note:
For the postulated initial defect size, the licensee used an aspect ratio of 10 for the circumferential flaw and an aspect ratio of 2 for the axial flaw. The NRC staff finds that postulated depth and aspect ratios that the licensee used are reasonable and consistent with the recommendations in EPRI MRP-115. The NRC staff, therefore, considered two cases in its independent analyses: (a) the initial flaws proposed by the licensee and (b) the existing subsurface axial flaws that are postulated as ID surface-connected PWSCC.
The axial and hoop WRS distributions provided in RA-19-0138 assumed a 50-percent ID weld repair. To develop these WRS distributions, the licensee used finite element analysis, which involves (1) modeling as-built geometry of the nozzle-to-safe end DM weld and safe end-to-pipe weld and (2) simulating the steps of the fabrication and welding process. The NRC staff notes that Section 3.6, Attributes of an Acceptable Residual Stress Analysis, of EPRI MRP-287 identifies the expectation that a 50-percent ID weld repair would be used to support analysis for NRC review. Based on these attributes, the NRC staff found the licensees calculated WRS distributions to be acceptable and utilized the licensees calculated WRSs in its independent analyses.
For Alloy 82/182, the licensee used the 75th percentile crack growth rate data for Alloy 182 based on EPRI MRP-115. The NRC staff finds that MRP-115 is a generally acceptable source for PWSCC growth flaws for Alloy 82/182 weld metals, and thus, is adequate for this analysis. The NRC staff, therefore, utilized the same PWSCC growth rates for Alloy 82/182 in its independent analyses.
For circumferential flaws, the NRC staffs analyses confirmed the licensees conclusion that the structural integrity of the RV cold leg nozzle-to-safe end DM butt welds would be maintained through the period of the proposed volumetric inspection extension. In addition, the NRC staffs analyses for the circumferential flaws show a significant margin exists in time for the postulated flaw to grow to the ASME Code allowable depth limit of 75 percent.
For axial flaws, the NRC staffs analyses found the existing subsurface flaw, if assumed an ID surface-connected flaw, could grow to exceed the ASME Code allowable depth limit of 75 percent and cause leakage within the proposed period between volumetric inspections (i.e.,
September 2013 to fall 2022). However, an axially-oriented flaw in the DM weld is bounded by low-alloy steel or stainless steel on either end. Since a PWSCC type flaw will not propagate into the stainless steel or the low alloy steel adjacent to the DM weld, an axially-oriented flaw cannot grow sufficiently large in length to cause rupture of the weld and adjacent piping system. Thus, the NRC staff applied risk insights to assess safety implications of piping with axial flaws that exceed the allowable limit, as discussed below.
3.8.3 Risk Insights Consideration The NRC staff considered risk insights to assess the results of its independent confirmatory analysis since the axial flaws do not exhibit adequate margin to the ASME Code-allowable depth limit of 75 percent. The NRC staffs risk insights were based on (1) prior volumetric and surface examinations and system leakage testing, (2) level of conservative inputs to the analysis to account for uncertainties, (3) leakage or failure of the welds that could lead to a concern for a loss-of-coolant accident, (4) existing plant leak detection and monitoring systems, and (5) operating experience.
While the NRC staffs analysis found that an axially-oriented PWSCC type flaw with conservative inputs could cause leakage during the period of the extended inspection interval, any such leakage would be small due to the morphology of PWSCC type flaws and will not directly challenge the safety of the plant. Further, the licensee has existing plant procedures such as plant walkdowns and leakage monitoring systems for the reactor coolant system, which provide added defense-in-depth measures to monitor the leaktightness of the RV cold leg nozzle-to-safe end DM butt welds.
The NRC staff also recognizes several conservative assumptions in the flaw tolerance analyses.
The primary conservatism is that the analyses assume that PWSCC has already initiated in the RV cold leg nozzle-to-safe end DM butt welds and has already grown to the depth of the existing fabrication flaws after the last volumetric inspection. If the postulated crack would have grown to become through-wall thickness of the DM welds, evidence of leakage would have been detected by the ASME Code system leakage test and associated visual examination (VT-2) performed every refueling outage. The licensee confirmed that there has been no leakage detected in the loop B RV cold leg nozzle-to-safe end DM butt weld.
Finally, the growth of an axial flaw would be limited in length by the width of the weld. Beyond the weld, the base materials of the pipe and the RV nozzle are not susceptible to the PWSCC degradation mechanism, and therefore, the axial flaw cannot grow sufficiently large in length to cause rupture of the weld. Thus, the likelihood of a loss-of-coolant accident occurring due to axial PWSCC flaws in the RV cold leg nozzle-to-safe end DM butt welds is low.
Therefore, based on the above application of risk insights, the NRC staff finds that there is reasonable assurance that the licensees proposed alternative has a minimal, if any, impact on safety.
4.0 CONCLUSION
As set forth above, the NRC staff determines that the proposed alternative provides an acceptable level of quality and safety for the RV cold leg nozzle-to-safe end DM butt welds by providing reasonable assurance that the structural integrity of the subject DM butt welds will be maintained. Accordingly, the NRC staff concludes that the licensee has adequately addressed all regulatory requirements set forth in 10 CFR 50.55a(z)(1). Therefore, the NRC staff authorizes the use of Relief Request RA-19-0138 for up to, and including, the fall 2022 refueling outage (RO-33) in the fifth 10-year ISI interval of Robinson Unit No. 2, which began on July 21, 2012, and is scheduled to end on February 18, 2023.
All other ASME Code,Section XI requirements for which relief was not specifically requested and authorized herein by the NRC staff remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributors: A. Rezai J. Tsao Date: April 29, 2020
- by e-mail OFFICE NRR/DORL/LPL2-2/PM NRR/DORL/LPL2-2/LA NRR/DNRL/NPHP/BC*
NAME PBuckberg LRonewicz MMitchell DATE 04/03/2020 04/02/2020 03/25/2020 OFFICE NRR/DORL/LPL2-2/BC NRR/DORL/LPL2-2/PM NAME UShoop AHon DATE 04/28/2020 04/29/2020