ML20237F344
| ML20237F344 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 09/21/2020 |
| From: | James Danna Plant Licensing Branch 1 |
| To: | Moul D NextEra Energy Seabrook |
| Poole J, NRR/DORL/LPLI, 415-2048 | |
| References | |
| EPID L-2020-LLR-0055, EPID L-2020-LLR-0056, EPID L-2020-LLR-0057 | |
| Download: ML20237F344 (6) | |
Text
SEABROOK STATION, UNIT NO. 1 - AUTHORIZATION OF ALTERNATIVE (RELIEF REQUEST 3IIR-7) FROM CERTAIN REQUIREMENTS OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS BOILER AND PRESSURE VESSEL CODE (EPIDs L-2020-LLR-0055, L-2020-LLR-0056, AND L-2020-LLR-0057)
LICENSEE INFORMATION Licensee: NextEra Energy Seabrook, LLC Licensee Address: Mr. Don Moul Executive Vice President, Nuclear Division and Chief Nuclear Officer NextEra Energy Seabrook, LLC Mail Stop: NT3/JW 15430 Endeavor Drive Jupiter, FL 33478 Plant Name and Unit: Seabrook Station, Unit No. 1 Docket No.: 50-443 APPLICATION INFORMATION Submittal Date: April 5, 2020 Submittal Agencywide Documents Access and Management System (ADAMS) Accession No.: ML20097A021 Supplement Date(s): NA Supplement ADAMS Accession No.: NA Licensee Proposed Alternative No. or Identifier: Relief Request 3IIR-7 Applicable Regulation: Title 10 of the Code of Federal Regulations (10 CFR)
Section 50.55a(z)(2)
Applicable Code Requirements: American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, IWA-2430(d)(1), IWB-2412 (Inspection Program B), and ASME Code Case N-770-5, as mandated by 10 CFR 50.55a(g)(6)(ii)(F) with conditions. It should be noted that the requirements in 10 CFR 50.55a(g)(6)(ii)(F) were revised by Federal Register Notice 85 FR 26540 dated June 3, 2020, and that the requirements in ASME Code Case N-770-5 shall be implemented with conditions instead of ASME Code Case N-770-2, at no later than 1 year after June 3, 2020. Therefore, this safety evaluation
refers to ASME Code Case N-770-5 in place of the licensees submittal citing of ASME Code Case N-770-2.
Applicable Code Edition and Addenda: The 2004 Edition with No Addenda of the ASME Code,Section XI Brief Description of the Proposed Alternative:
In Relief Request 3IIR-7, the licensee proposed to defer the following third inservice inspection (ISI) interval examinations from the April 2020 refueling outage (OR20) to the fall 2021 refueling outage (OR21) at Seabrook Station, Unit No. 1 (Seabrook).
Volumetric examinations of the pressurizer circumferential shell-to-head weld and intersecting portions (1 foot each) of longitudinal shell-to-head welds, per Examination Category B-B in Table IWB-2500-1 of the ASME Code,Section XI Visual examinations of reactor vessel (RV) interior surfaces, RV interior attachment welds, and core support structure surfaces, per Examination Categories B-N-1, B-N-2, and B-N-3, respectively In addition, the licensee has determined that in order to be in compliance with the regulatory requirements and the provisions of the ASME Code,Section XI, IWB-2412(b) and Code Case N-770-5, the licensee is required to volumetrically examine the RV hot leg nozzle-to-safe end dissimilar metal (DM) butt weld SE-301-121-H D (classified as Inspection Item E in Table 1 of Case N-770-5) during each of the three subsequent inspection periods after application of mechanical stress improvement (MSIP). In order to complete its third subsequent reexamination during the units current inspection period and interval, the licensee determined that it requires U.S. Nuclear Regulatory Commission (NRC) approval to extend the current inspection period and interval by 6 weeks beyond what the licensee would be permitted to do under its current licensing basis such that the units fall 2021 refueling outage would fall within the current inspection period and interval.
The licensee stated that Seabrook is currently in the third ISI interval, which began on August 19, 2010, and was originally scheduled to end on August 18, 2020. The proposed alternative in 3IIR-7 is requested to extend the Seabrook third ISI interval by 6 weeks beyond the ASME Code,Section XI, IWA-2430(d)(1) allowed extension of 1 year for the components identified in Section 1.0 of 3IIR-7. NRC approval of this alternative allows for the third ISI interval to end at the conclusion of the fall 2021 refueling outage. This extension will neither affect the start of the fourth ISI interval, which is scheduled to begin on August 19, 2020, and end on August 18, 2030, nor impact the overall schedule of ISI examinations at Seabrook.
The licensee stated that NRC approval of the proposed alternative in 3IIR-7 allows for a coordinated schedule for the examination of mitigated weld SE-301-121-H D, Examination Categories B-N-1, B-N-2, and B-N-3 RV interior items and remaining mitigated RV hot and cold leg nozzle-to-safe end butt welds to be performed in fall 2021 refueling outage. Thus, removal of the RV lower internal (i.e., core barrel) assembly, which is considered a critical lift and is necessary for examination access to the inside of the RV, occurs once rather than twice within 5 years.
The licensee reported that hardship is due to the ongoing Coronavirus Disease 2019 (COVID-19) pandemic. To minimize the risk of viral transmission to Seabrook personnel, the
licensee has to limit the offsite inspection personnel entering the plant, and it must implement social distancing between onsite workers. Further, there has been increasing uncertainty that the licensee would have appropriate augmented support workers needed to assist with these examinations. Accordingly, the licensee determined that performing the subject examinations to meet the above ASME Code schedule requirements would not provide an increase in the level of quality and safety necessary to compensate for the hardship imposed by performing these examinations during the COVID-19 pandemic.
For additional details on the licensees submittal, please refer to the document located at the ADAMS accession number identified above.
REGULATORY EVALUATION Regulatory Basis: 10 CFR 50.55a(z)(2)
Adherence to Section XI of the ASME Code is mandated by 10 CFR 50.55a(g)(4). Paragraph 50.55a(g)(4) of 10 CFR states, in part, that ASME Code Class 1, 2, and 3 components must meet the requirements, except the design and access provisions and the pre-service examination requirements, set forth in Section XI of editions and addenda of the ASME Code that are incorporated by reference in 10 CFR 50.55a(a)(1)(ii).
Pursuant to 10 CFR 50.55a(g)(6)(ii)(F), licensees of existing operating pressurized-water reactors (PWR) shall implement the requirements of ASME Code Case N-770-5, 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 ActivitiesSection XI, Division 1, instead of ASME Code Case N-770-2, subject to the conditions specified in paragraphs (g)(6)(ii)(F)(2) through (16) of 10 CFR 50.55a, by no later than 1 year after June 3, 2020.
Section 50.55a(z) of 10 CFR states that alternatives to the requirements of paragraphs (b) through (h) of Section 50.55a 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 would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Pursuant to 10 CFR 50.55a(z)(2), the licensee submitted its proposed alternative on the basis that 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.
TECHNICAL EVALUATION The NRC staff reviewed Relief Request 3IIR-7 pursuant to 10 CFR 50.55a(z)(2). On April 8, 2020 (ADAMS Accession No. ML20101H391), the NRC staff verbally authorized the use of Relief Request 3IIR-7. In its verbal authorization, the NRC staff determined that the proposed alternative to defer the subject examinations until the fall 2021 refueling outage, 6 weeks beyond the August 18, 2021, deadline to meet the ASME Code inspection schedule requirements is technically justified. The staffs written evaluation below documents the technical basis for the NRCs verbal authorization.
Reasonable Assurance of Structural Integrity The NRC staff considered whether the licensees proposed alternative provides reasonable assurance of structural integrity and leaktightness of the RV hot leg nozzle-to-safe end DM butt weld (SE-301-121-H D) based on: (1) the operating experience associated with MSIP for mitigating cracking; (2) the post mitigation examinations results; and (3) other inspections monitoring leak tightness. The NRC staff verified that:
- 1) The licensee mitigated the RV hot leg nozzle-to-safe end DM butt weld, which had flaws, by MSIP in October 2009. MSIP altered the residual stresses in the inner through-wall region of the weld to compression. The operating experience has shown that application of MSIP inhibits the growth of existing flaws and the initiation of new flaws in the weld.
- 2) In April 2011 and 2014, following the MSIP, the licensee volumetrically examined the RV hot leg nozzle-to-safe end DM butt weld. These examinations found no growth of existing flaws and no evidence of new flaws in the weld.
- 3) The licensee performed the ASME Code-required system leakage testing accompanied with visual examination (VT-2) and regular walkdowns during the plants ascension to full power to monitor the leaktightness of the RV hot leg nozzle-to-safe end DM butt weld.
No evidence of a through-wall leak has been identified.
The NRC staff found that, given the existence of compressive residual stresses in the inner through-wall region of the weld resulting from the MSIP and the favorable examination results after MSIP, the licensees proposed 6-week inspection deferral beyond that allowed by the ASME Code is acceptable and provides reasonable assurance of the structural integrity for the RV hot leg nozzle-to-safe end DM butt weld.
The licensee reported in its submittal that the subject pressurizer welds, RV interior items, and core support structure have all been examined for the past two ISI intervals with no relevant indications identified. Based on its independent review of industry operating experience for PWR internal component aging degradation, the NRC staff independently confirmed that the RV interior items and core support structure have not exhibited aging degradation that would prompt a structural integrity concern based on a 6-week ISI deferral. The NRC staff identified that the pressurizer shell-to-head circumferential and intersecting long-seam pressure boundary welds have not shown any active degradation in the PWR fleet, and these types of low alloy steel pressure-retaining vessel materials are not prone to any aging mechanism that would result in the formation of new flaws during their design life. The NRC staff noted that the licensee also continues to perform the ASME Code-required system leakage testing and associated VT-2, as described above, providing additional assurance of structural integrity.
Based on its review of the information above, the NRC staff found that the licensees proposed 6-week inspection deferral beyond that allowed by the ASME Code, provides reasonable assurance of the structural integrity for all the components addressed in the licensees proposed alternative.
Basis for Hardship The NRC staff determined that the licensee adequately documented the conditions resulting from COVID-19 that could pose health hazards to personnel if examinations of the subject components were performed during the April 2020 refueling outage to meet ISI schedule
requirements. Specifically, the licensee needed to limit the number of personnel entering the site, and it needed to implement social distancing between onsite workers to minimize the risk of viral transmission. The NRC staff acknowledges that these precautions are necessary to protect Seabrook personnel who are relied on to safely operate the plant. The NRC staff noted that performance of the subject examinations requires that personnel work in close proximity to one another, which is contrary to Federal guidelines for protecting workers from viral transmission. The NRC staff also acknowledges that this pandemic has resulted in uncertainty that augmented support workers would even be available to assist with the ISI activities needed to complete these examinations during the April 2020 refueling outage.
As the ongoing COVID-19 pandemic is of sufficient severity and magnitude to warrant an emergency determination under Section 501(b) of the Robert T. Stafford Disaster Relief and Emergency Assistance Act, 42 U.S.C. Sections 5121-5207, and the U.S. Center for Disease Control has determined that COVID-19 poses a serious public health risk, the NRC staff finds that the licensees hardship justification is acceptable.
In summary, considering the component structural integrity findings documented above, the NRC staff determined that performing the subject examinations to comply with the ASME Code schedule requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
CONCLUSION As discussed above, the NRC staff has determined that complying with the subject requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. The licensees proposed alternative provides reasonable assurance of the structural integrity for the subject components. The NRC staff concludes that the licensee has adequately addressed the regulatory requirements in 10 CFR 50.55a(z)(2).
Therefore, the NRC staff authorizes the use of the proposed alternative described in Relief Request 3IIR-7 for Seabrook until the next planned ISI during refueling outage OR21 scheduled for fall 2021.
All other ASME Code,Section XI requirements for which an alternative was not specifically requested and approved in this proposed alternative remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributors: A. Rezai C. Sydnor Date: September 21, 2020 Digitally signed by James James G. G. Danna Date: 2020.09.21 Danna 16:45:51 -04'00' James G. Danna, Chief Plant Licensing Branch 1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
ML20237F344 OFFICE NRR/DORL/LPL1/PM NRR/DORL/LPL1/LA NRR/DNRL/NVIB/BC NAME JPoole LRonewicz MMitchell DATE 08/25/2020 08/25/2020 08/07/2020 OFFICE NRR/DNRL/NPHP/BC NRR/DORL/LPL1/BC NAME HGonzalez JDanna DATE 08/18/2020 09/21/2020