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MONTHYEARML20089A0072020-03-31031 March 2020 Verbal Authorization by the Office of Nuclear Reactor Regulation for Relief Request I4R-23 Project stage: Approval ML20092M0032020-03-31031 March 2020 Email Re Limerick Generating Station, Unit 1 (LGS) - Suppression Pool Relief Request Verbal Authorization Related to COVID-19 Issues Project stage: Approval ML20089A0012020-04-20020 April 2020 Issuance of Relief Request I4R-23 Associated with Pandemic-Related Issues - Examination of Containment Surfaces Requiring Augmented Examination (Category E-C) (EPID L-2020-LLR-0044 (COVID-19)) Project stage: Approval 2020-03-31
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Category:Letter
MONTHYEARML24339B7292024-12-18018 December 2024 Amd - Constellation - Adoption of TSTF-591 ML24318A9432024-11-13013 November 2024 – Notification of Conduct of Phase II Inspection of Title 10 of the Code of Federal Regulations 50.69, Risk-Informed Categorization and Treatment of Structures, Systems, and Components for Nuclear Power Reactor IR 05000352/20240032024-11-0808 November 2024 Integrated Inspection Report 05000352/2024003 and 05000353/2024003 ML24310A0062024-11-0808 November 2024 – Acceptance of Requested Licensing Action Modification to Technical Specifications 3.6.1.2 and Main Stem Isolation Valve Leakage Requirements Amendment ML24317A1432024-11-0404 November 2024 Constellation Energy Generation, LLC, 2024 Annual Report - Guarantees of Payment of Deferred Premiums ML24151A3842024-10-31031 October 2024 – Issuance of Amendment Nos. 264 and 226 Support to Digital Modernization Project Installation (EPID L-2023-LLA-0025) and Exemption from the Requirements of 10 CFR 50.62 ML24303A2782024-10-29029 October 2024 10 CFR 50.46 Annual Report ML24303A0902024-10-29029 October 2024 Operator Licensing Examination Approval ML24299A2642024-10-25025 October 2024 Response to Request for Supplemental Information Needed for Acceptance of Requested Licensing Action Regarding Primary Containment Leakage Technical Specifications IR 05000352/20240122024-10-17017 October 2024 Commercial Grade Dedication Inspection Report 05000352/2024012 and 05000353/2024012 RS-24-093, Response to Request for Additional Information - Alternative Request to Utilize Code Case OMN-32, Alternative Requirements for Range and Accuracy of Pressure, Flow, and Differential Pressure Instruments Used in Pump Tests2024-10-10010 October 2024 Response to Request for Additional Information - Alternative Request to Utilize Code Case OMN-32, Alternative Requirements for Range and Accuracy of Pressure, Flow, and Differential Pressure Instruments Used in Pump Tests ML24274A2372024-10-0707 October 2024 – Supplemental Information Needed for Acceptance of Requested Licensing Action Regarding Primary Containment Leakage Technical Specifications ML24278A3022024-10-0404 October 2024 Supplement to License Amendment Request to Revise Technical Specifications and Exemption Request from Requirements of 10 CFR 50.62 ATWS Rule to Support the Digital Modernization Project Installation - Rev Unit 2 Technical Spec ML24275A2442024-10-0303 October 2024 Reassignment of the U.S. Nuclear Regulatory Commission Branch Chief, Division of Operating Reactor Licensing ML24263A0032024-09-27027 September 2024 Generation Station, Units 1 and 2 – Regulatory Audit Plan Supporting Review of the Component Interface Module System of the Limerick Digital Instrumentation and Controls License Amendment Request (EPID L-2022-LLA-0140) (Redacted) ML24243A0482024-09-19019 September 2024 Generation Station, Unit Nos. 1 and 2 - Schedule Update for License Amendment Request to Replace Existing Safety-Related Analog Control Systems with a Single Digital Plant Protection System ML24215A4042024-09-18018 September 2024 Request for Withholding Information from Public Disclosure IR 05000352/20244202024-09-16016 September 2024 – Security Baseline Inspection Report 05000352/2024420 and 05000353/2024420 RS-24-090, Response to Request for Additional Information - Relief Request Concerning Extension of Permanent Relief from Ultrasonic Examination of Reactor Pressure Vessel Circumferential Shell Welds2024-09-12012 September 2024 Response to Request for Additional Information - Relief Request Concerning Extension of Permanent Relief from Ultrasonic Examination of Reactor Pressure Vessel Circumferential Shell Welds IR 05000352/20250102024-09-10010 September 2024 Information Request for Quadrennial Baseline Comprehensive Engineering Team Inspection; Notification to Perform Inspection 05000352/2025010 and 05000353/2025010 ML24255A8642024-09-0606 September 2024 Rscc Wire & Cable LLC Dba Marmon Industrial Energy & Infrastructure - Part 21 Retraction of Final Notification IR 05000352/20230022024-09-0404 September 2024 Reissued Integrated Inspection Report 05000352/2023002 and 05000353/2023002 IR 05000352/20240052024-08-29029 August 2024 Updated Inspection Plan for Limerick Generating Station, Units 1 and 2 (Report 05000352/2024005 and 05000353/2024005) ML24241A1952024-08-28028 August 2024 License Amendment Request for Modification to Technical Specification 3.6.1.2 and Main Steam Isolation Valve Leakage Rate Requirements ML24239A3972024-08-23023 August 2024 Rssc Wire & Cable LLC Dba Marmon - Part 21 Final Notification - 57243-EN 57243 ML24163A3902024-08-14014 August 2024 Request for Withholding Information from Public Disclosure ML24220A2392024-08-12012 August 2024 Correction to Technical Specification Page 3/4 3-11 in Amendment No. 225 IR 05000352/20240022024-08-12012 August 2024 Integrated Inspection Report 05000352/2024002 and 05000353/2024002 ML24222A6772024-08-0909 August 2024 Response to Request for Additional Information for Application to Revise Technical Specifications to Adopt TSTF-591-A, Revise Risk Informed Completion Time (RICT) Program Revision 0 and Revise 10 CFR 50.69 License Condition ML24204A0712024-07-29029 July 2024 Issuance of Amendment Nos. 263 and 225 Technical Specifications for Main Steam Line Tunnel Temperature ML24208A0962024-07-25025 July 2024 57243-EN 57243 - Rssc Wire & Cable LLC, Dba Marmon - Part 21 Notification ML24208A1592024-07-25025 July 2024 Regulatory Audit Plan Supporting Review of the System Development Portion of Limerick Digital Instrumentation and Controls License Amendment Request (EPID L-2022-LLA-0140) - Non-Proprietary ML24201A1662024-07-19019 July 2024 Response to Request for Additional Information for License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam L ML24199A1842024-07-15015 July 2024 RAI-LAR for Limerick EPID: L-2024-LLA-0079- Use This Version RS-24-070, Independent Spent Fuel Storage Installation, Nine Mile Point, Units 1 and 2, Quad Cities, Units 1 and 2, R. E. Ginna - Nuclear Radiological Emergency Plan Document Revisions2024-07-12012 July 2024 Independent Spent Fuel Storage Installation, Nine Mile Point, Units 1 and 2, Quad Cities, Units 1 and 2, R. E. Ginna - Nuclear Radiological Emergency Plan Document Revisions ML24180A1572024-06-28028 June 2024 Request to Return and Replace WEC Documents (EQ-EV-386-GLIM, EQ-QR- 433-GLIM, and APP-GW-GLR-611), to Meet 10CFR2.390 Request to Withdraw from Public Disclosure Requirements ML24170A7702024-06-20020 June 2024 Individual Notice of Consideration of Issuance of Amendments to Renewed Facility Operating Licenses, Proposed No Significant Hazards Consideration Determination, Opportunity for Hearing(Epid L-2024-LLA-0079) LTR 05000352/LER-2024-003, Core Operating Limits Report Thermal Limit Exceeded for Unit 1 Fuel Bundle GGK1232024-06-18018 June 2024 Core Operating Limits Report Thermal Limit Exceeded for Unit 1 Fuel Bundle GGK123 ML24166A1142024-06-14014 June 2024 Response to Requests for Additional Information (RAIs 15 Through 23) for License Amendment Request to Revise the Licensing and Design Basis to Incorporate the Replacement of Existing Safety-Related Analog Control Systems RS-24-061, Constellation Energy Generation, LLC, Response to NRC Regulatory Issue Summary 2024-01, Preparation and Scheduling of Operator Licensing Examinations2024-06-14014 June 2024 Constellation Energy Generation, LLC, Response to NRC Regulatory Issue Summary 2024-01, Preparation and Scheduling of Operator Licensing Examinations ML24165A2642024-06-13013 June 2024 License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam Line Tunnel Temperature TS 3/4.7.9 05000352/LER-2024-001, Leakage for the Unit 1 `B Outboard Main Steam Isolation Valve Exceeded Technical Specification Limit2024-06-10010 June 2024 Leakage for the Unit 1 `B Outboard Main Steam Isolation Valve Exceeded Technical Specification Limit ML24151A2882024-06-10010 June 2024 Request for Withholding Information from Public Disclosure ML24151A2012024-06-10010 June 2024 Request for Withholding Information from Public Disclosure 05000352/LER-2024-002, Invalid Actuation Due to a Trip of 1B Reactor Protection System Circuit Breaker2024-06-10010 June 2024 Invalid Actuation Due to a Trip of 1B Reactor Protection System Circuit Breaker ML24150A0242024-05-29029 May 2024 Notification of Commercial Grade Dedication Inspection (05000352/2024012 and 05000353/2024012) and Request for Information ML24149A2112024-05-28028 May 2024 Supplement to License Amendment Request to Revise Technical Specifications and Exemption Request from Requirements of 10CFR50.62 ATWS Rule to Support the Digital Modernization Project Installation ML24079A0762024-05-23023 May 2024 Issuance of Amendments to Adopt TSTF 264 IR 05000352/20243022024-05-20020 May 2024 Revised Initial Operator Licensing Examination Report 05000352/2024302 and 05000353/2024302 2024-09-06
[Table view] Category:Safety Evaluation
MONTHYEARML24339B7292024-12-18018 December 2024 Amd - Constellation - Adoption of TSTF-591 ML24204A0712024-07-29029 July 2024 Issuance of Amendment Nos. 263 and 225 Technical Specifications for Main Steam Line Tunnel Temperature ML23321A2362023-12-14014 December 2023 Issuance of Amendment Nos. 262 and 224 Adoption of TSTF-477, Revision 3 and Associated Technical Specification Changes ML23094A1792023-05-17017 May 2023 Amd Nos. 261 & 223 Alternate Seismic Approach for Risk-Informed Categorization & Treatment of Structures, Systems, Components for NPR & Denial of Proposed Alternative Defense in Depth & Pressure Boundary Component-Partial Denial SE Encl 4 ML23094A1712023-05-17017 May 2023 Amd Nos. 261 & 223 Alternate Seismic Approach for Risk-Informed Categorization & Treatment of Structures, Systems and Components for NPR and Denial Proposed Alternative Defense in Depth and Pressure Boundary Component ML23089A1242023-05-17017 May 2023 Issuance of Amd Nos. 261 & 223 Alternate Seismic Approach for Risk-Informed Categorization and Treatment of Structures, Systems a Components for NPR and Denial Proposed Alternative Defense in Depth and Pressure Boundary Component ML23114A2522023-04-28028 April 2023 Request to Use a Provision of a Later Edition of the ASME Boiler & Pressure Vessel Code, Section XI ML22348A1762023-03-0707 March 2023 Issuance of Amendment Nos. 260 and 222 Regarding Technical Specifications 3.3.7.4, Remote Shutdown System Instrumentation and Controls ML23005A0082023-02-23023 February 2023 Technical Specifications to Correct Non-conservative Technical Specification Table 3.3.2-1 for Main Steam Line Isolation Trip Function 1.G (EPID L 2020 Lla 0034) Amds. 259 and 221 ML22272A0372023-01-0303 January 2023 Issuance of Amendment Nos. 258 and 220 Regarding Technical Specifications 3/4.8.1, AC Sources-Operating and 3/4.5.1, ECCS-Operating ML22293B8052022-11-30030 November 2022 Constellation Energy Generation, Llc_Fleet - Request to Authorize Use Honeywell Mururoa V4F1 R Supplied Air Suits ML22090A0862022-04-29029 April 2022 Amendments to Adopt TSTF-541,Rev.2,Add Exceptions to Surveillance Requirements for Valves,Dampers Locked in Actuated Position ML22094A0012022-04-15015 April 2022 Constellation Energy Generation, LLC - Proposed Alternative for Repair of Water Level Instrumentation Partial Penetration Nozzles (Epids L-2021-LLR-0057 and L-2021-LLR-0058) ML22003A1862022-02-17017 February 2022 Issuance of Amendment Nos. 256 and 218 Technical Specification Changes Related to Technical Specifications Task Force (TSTF) Traveler 205-A, Revision 3, Revision of Channel Calibration, Channel Functional Test, and Related Definitions ML21347A0382022-01-13013 January 2022 Issuance of Amendments to Revise Reactor Coolant Leakage Requirements ML21277A2482021-11-16016 November 2021 Letter with Enclosure 4, Safety Evaluation for Transfer of Licenses and Draft Conforming License Amendments (Public Version) ML21280A0782021-10-27027 October 2021 Proposed Alternative to Use of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code Case N-893 (Epids L-2020-LLR-0147 and L-2020-LLR-0148) ML21181A0442021-09-28028 September 2021 Issuance of Amendment Nos. 253 and 215 Technical Specification Changes Related to Relocation of Pressure and Temperature Limit Curves to the Pressure and Temperature Limits Report ML21230A2062021-09-0303 September 2021 Proposed Alternative to Use ASME OM Code Case OMN-28 ML21172A2682021-09-0202 September 2021 Issuance of Relief Request I4r-24 Associated with Residual Heat Removal Heat Exchanger Category C-A and C-B Examinations for the Remainder of the Fourth 10-Year Isi Interval and Up to the End of the 60-Year Operating License ML21216A2202021-08-0505 August 2021 Proposed Alternative to Eliminate Certain Documentation Requirements for Pressure Retaining Bolting ML21166A1682021-06-25025 June 2021 ML21032A2702021-02-22022 February 2021 Issuance of Amendment Nos. 252 and 214, Revise Technical Specifications to Adopt Technical Specifications Task Force Traveler TSTF-582, Revision 0, RPV WIC Enhancements ML21013A0052021-02-0404 February 2021 Issuance of Amendments to Adopt Technical Specifications Task Traveler TSTF-568, Revise Applicability of BWR/4 TS 3.6.2.5 and TS 3.6.3.2 ML21028A6732021-02-0303 February 2021 Request to Use a Provision of Later Edition of the ASME Boiler and Pressure Vessel Code, Section XI (EPID L-2020-LLR-011 ML20322A0092020-12-10010 December 2020 Issuance of Alternative Requests 41-VRR-8 and 41-VRR-7 Regarding Certain Inservice Testing Program Requirements for Safety Relief Valves ML20255A0632020-12-0101 December 2020 Issuance of Amendment Nos. 250 and 212 Technical Specification Changes Related to Inservice Testing Program of the Safety Relief Valves ML20239A7252020-11-30030 November 2020 Issuance of Amendment Nos. 249 and 211 Adopt TSTF-484, Revision 0, Use of TS 3.10.1 for Scram Time Testing Activities ML20280A7572020-11-0505 November 2020 Revised Safety Evaluation of Relief Requests GVRR-8, 11 PRR-1, 90 PRR-1, and 47 VRR-2 Regarding the Fourth 10-Year Interval of the Inservice Testing Program (EPID L-2018-LLR-0384 Through EPID L-2018-LLR-0387) ML20287A1302020-11-0505 November 2020 Review of Quality Assurance Program Changes ML20269A2002020-09-30030 September 2020 Request to Use a Provision of Later Edition of the ASME Boiler and Pressure Vessel Code, Section XI (EPID L2020-LLR-0117 ML20232A1712020-09-0101 September 2020 Request to Use Alternative Code Case OMN-26 ML20160A4592020-08-0707 August 2020 Issuance of Amendment Nos. 248 and 210 Revise Technical Specifications to Support Implementation of 10 CFR 50.69 ML20141L6362020-07-10010 July 2020 Issuance of Amendments Based on TSTF-427,Allowance for Nontechnical Specification Barrier Degradation on Supported System Operability,Rev 2 ML20134H9402020-07-0808 July 2020 Issuance of Amendments Revising the High Radiation Area Administrative Controls ML20090B4102020-06-0202 June 2020 Issuance of Relief Request GVRR-9 Associated with Pandemic-Related Issues - Inservice Testing Interval Extension for Motor Operated Valves (EPID L-2020-LLR-0046 (COVID-19)) ML20113F0412020-04-30030 April 2020 Proposed Alternative to the Submittal Schedule for Certain Reports (COVID-19) ML20089A0012020-04-20020 April 2020 Issuance of Relief Request I4R-23 Associated with Pandemic-Related Issues - Examination of Containment Surfaces Requiring Augmented Examination (Category E-C) (EPID L-2020-LLR-0044 (COVID-19)) ML20098C9222020-04-0909 April 2020 Issuance of Amendment No. 245 Regarding Technical Specifications Change to Allow a One-Time Increase in Main Steam Isolation Valve Allowable Leakage Rate (EPID L-2020-LLA-0064) (Emergency Circumstances) ML20021A0702020-04-0606 April 2020 Issuance of Amendments to Delete License Conditions for Decommissioning Trusts ML19351E3762020-03-11011 March 2020 Issuance of Amendment Nos. 241 and 204 Revise Technical Specification 6.8.4.g to Extend Containment Integrated Leak Rate Test Frequency (EPID L-2019-LLA-007 ML20034F6372020-02-28028 February 2020 Issuance of Amendment Nos. 240 and 203 to Implement TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4B ML19331A7252020-02-14014 February 2020 Issuance of Amendments Revising Emergency Action Levels ML20028E3992020-02-0404 February 2020 Proposed Alternative to Use ASME Code Case N-879 ML19302E7002019-12-18018 December 2019 R. E. Ginna, LaSalle, Limerick, Nine Mile Point, Peach Bottom, and Quad Cities -Issuance of Amendments to Remove Table of Contents from Technical Specifications ML19207A0062019-10-0303 October 2019 Issuance of Amendment Nos. 237 and 200 Revise Technical Specifications to Allow Penetration Flow Path Isolation for Inoperable Isolation Actuation Instrumentation ML19269C5342019-09-27027 September 2019 Proposed Alternative to Use Encoded Phased Array Ultrasonic Examination Techniques ML19176A0332019-08-28028 August 2019 Issuance of Amendments to Adopt TSTF-564, Safety Limit MCPR ML19192A2442019-07-18018 July 2019 Proposed Alternative to Use ASME Code Cases N-878 and N-880 ML19078A0182019-05-24024 May 2019 Issuance of Amendment Nos. 235, 198, 14, 325, and 328 to Revise the Emergency Response Organization Staffing Requirements 2024-07-29
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April 20, 2020 Mr. Bryan C. Hanson Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
LIMERICK GENERATING STATION, UNIT 1 - ISSUANCE OF RELIEF REQUEST I4R-23 ASSOCIATED WITH PANDEMIC-RELATED ISSUES -
EXAMINATION OF CONTAINMENT SURFACES REQUIRING AUGMENTED EXAMINATION (CATEGORY E-C) (EPID L-2020-LLR-0044 [COVID-19])
Dear Mr. Hanson:
By letter dated March 28, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20088B022), Exelon Generation Company, LLC (the licensee),
submitted a request for relief from the requirements of the American Society of Mechanical Engineers Boiler & Pressure Vessel Code (ASME Code),Section XI, Subsection IWE, for the first period of the third 10-year containment inservice inspection interval for Limerick Generating Station (Limerick), Unit 1.
Specifically, pursuant to the requirements of Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(2), the licensee requested to postpone required ASME Code,Section XI inspections of submerged areas of the suppression pool liner and suppression pool vent system on the basis that complying with the specified requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
On March 31, 2020 (ADAMS Accession No. ML20089A007), the NRC verbally authorized the use of Relief Request I4R-23 at Limerick, Unit 1.
The NRC staff has determined that the proposed alternative in Relief Request I4R-23 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 the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, the NRC staff authorizes the proposed alternative at Limerick, Unit 1, for the first period of the third 10-year inservice inspection interval.
All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in the subject request for relief remain applicable, including third-party review by the Authorized Nuclear lnservice Inspector.
If you have any questions, please contact the Limerick Project Manager, V. Sreenivas, at 301-415-2597 or V.Sreenivas@nrc.gov.
Sincerely,
/RA/
James G. Danna, Chief Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-352
Enclosure:
Safety Evaluation cc: Listserv
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PROPOSED ALTERNATIVE REQUEST I4R-23 REGARDING CONTAINMENT SUPPRESSION POOL AUGMENTED INSPECTION REQUIREMENTS EXELON GENERATION COMPANY, LLC.
LIMERICK GENERATING STATION, UNIT 1 DOCKET NO. 50-352
1.0 INTRODUCTION
By letter dated March 28, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20088B022), Exelon Generation Company, LLC (the licensee),
requested relief from the requirements of the American Society of Mechanical Engineers Boiler
& Pressure Vessel Code (ASME Code),Section XI, Subsection IWE, for the first period of the third 10-year containment inservice inspection (ISI) interval for Limerick Generating Station (Limerick), Unit 1. Specifically, pursuant to the requirements of Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(2), the licensee requested to postpone required ASME Code,Section XI inspections of submerged areas of the suppression pool liner and suppression pool vent system on the basis that complying with the specified requirement would result in hardship or unusual difficulty, without a compensating increase in the level of quality and safety.
2.0 REGULATORY EVALUATION
Pursuant to 10 CFR 50.55a(g)(4), throughout the service life of a nuclear power facility, components that are classified as Class MC pressure retaining components must meet the requirements set forth in the ASME Code,Section XI, Subsection IWE, as incorporated by reference in paragraph (a)(1)(ii), subject to the conditions listed in 10 CFR 50.55a(b)(2)(ix). The ASME Code,Section XI, Subsection IWE, provides rules for ISI of Class MC pressure-retaining components and of metallic shells of Class MC containment structures. The appropriate edition of the code to be used for successive 120-month inspection intervals is determined pursuant to 10 CFR 50.55a(g)(4)(ii). Alternatives to the requirements of 10 CFR 50.55a(g)(4) may be authorized by the U.S. Nuclear Regulatory Commission (NRC) pursuant to 10 CFR 50.55a(z)(2) if the licensee demonstrates that complying with the specified requirement would result in hardship or unusual difficulty, without a compensating increase in the level of quality and safety.
Pursuant to 10 CFR 50.55a(g)(4)(ii), the licensees code of record for the third 10-year containment ISI interval is the 2007 Edition with 2008 Addenda of the ASME Code,Section XI.
Subparagraph IWE-2420, Successive Inspections, requires that when examination results detect flaws, areas of degradation, or conditions that require an engineering evaluation in accordance with IWE-3000 or IWE-2500(d), and the component is found acceptable for continued service, the areas shall be reexamined during the next inspection period in accordance with Table IWE-2500-1 (E-C). Table IWE-2500-1 (E-C), Examination Category E-C, Containment Surfaces Requiring Augmented Examination, Item E4.11, requires visual examination (VT-1) of identified surface areas each inspection period until the areas examined remain essentially unchanged for the next inspection period.
3.0 TECHNICAL EVALUATION
3.1 Licensees Proposed Alternative The licensees proposed alternative in Relief Request I4R-23 is applicable to submerged metal containment surfaces requiring successive inspections and augmented examination.
Specifically, the request applies to portions of the submerged areas of the suppression pool liner and submerged areas of the downcomers and is against the following examination requirements of the ASME Code,Section XI, Subsection IWE.
Subparagraph IWE-2420 requires that when examination results detect flaws, areas of degradation, or conditions that require an engineering evaluation in accordance with IWE-3000 or IWE-2500(d) and the component is found acceptable for continued service, the areas shall be reexamined during the next inspection period in accordance with Table IWE-2500-1 (E-C).
Table IWE-2500-1 (E-C), Item E4.11, requires visual examination (VT-1) of identified surface areas each inspection period until the areas examined remain essentially unchanged for the next inspection period.
The licensees proposed alternative corresponding to the above code requirements is a one-time deferral of the required inspections. The required inspections will be postponed and completed no later than the next refueling outage (Li1R19) in the spring of 2022. The alternative is requested for the duration of the first period of the third 10-year IWL ISI interval.
The licensee requested authorization for use of the proposed alternative pursuant to 10 CFR 50.55a(z)(2) on the basis that complying with the specified requirement would result in hardship or unusual difficulty, without a compensating increase in the level of quality and safety, due to the ongoing national emergency related to the COVID-19 pandemic.
In its request, the licensee noted that on March 13, 2020, the U.S. government declared a national emergency associated with the COVID-19 outbreak. In response to the outbreak, the Centers for Disease Control (CDC) recommended social distancing, which is defined as remaining out of congregate settings, avoiding mass gatherings, and maintaining distance (approximately 6 feet or 2 meters) from others when possible. The licensee noted that the inspections of containment surfaces require work in close spaces and cannot be completed while implementing the recommendation for social distancing. Due to the COVID-19 pandemic, and to comply with CDC guidance, the licensee requested relief associated with performing successive and augmented inspections of the suppression pool liner and downcomers during the spring 2020 refueling outage (Li1R18). These inspections are required by ASME Code,Section XI, IWE-2420(b), and Table IWE-2500-1 (E-C), Item No. E4.11. These inspections are required for locations that did not meet acceptance criteria during the previous inspection (spring 2016, LiR16) and were accepted for continued service by engineering evaluation. The licensee proposed to perform the required inspections during the next refueling outage (spring 2022, Li1R19).
During the spring 2016 refueling outage, an underwater inspection of 100 percent of the accessible areas of the suppression pool liner and downcomers was performed. The results of that inspection are as follows:
all areas of localized corrosion greater than 45 mils were recoated, the maximum depth of localized corrosion on the liner that was not recoated was 44.7 mils, the maximum depth of general area corrosion on the liner was 44 mils for the liner, and the maximum depth of localized corrosion identified on any downcomer was 35 mils.
In addition to the results from 2016, results from inspections during outages in 1996, 2004, 2012, and 2016 have been used to develop a general corrosion rate. This data has shown a corrosion rate of approximately 1 to 2 mils per year with a maximum rate of 3.6 mils per year between 2012 and 2016.
The licensee also developed site-specific acceptance criteria for the suppression pool and downcomers, which ensure the structural integrity of the components is maintained. Based on the analysis, the maximum allowable metal loss was determined to be 125 mils for the general area of the liner plate, 187.5 mils for localized areas, and 62.5 mils for the downcomers. Using the most recent data from the 2016 inspection and the corrosion rate of 3.6 mils, the licensee estimated the most restrictive location would be the downcomers and the metal loss at the beginning of the 2022 refueling outage on the downcomers would be 56.6 mils. This value is below the associated acceptance criteria of 62.5 mils.
3.2
NRC Staff Evaluation
The staff reviewed the information provided in the proposed alternative request and noted that the CDC has identified social distancing as a method for slowing the spread of the COVID-19 virus and noted that the subject inspections cannot be properly completed while following the social distancing guidelines. Therefore, completing the inspections as required would result in a hardship or difficulty.
In addition, the staff reviewed the licensees data and noted that an average corrosion rate of 1 to 2 mils per year, with a maximum rate of 3.6 mils, are reasonable corrosion rates for uncoated carbon steel components in the suppression pool environment. To add conservatism to its estimates, the licensee used the maximum corrosion rate it has identified since monitoring the suppression pool, which was measured during the last inspection (2016). The NRC staff notes that with this maximum corrosion rate (3.6 mils per year), the estimated metal loss at the beginning of the 2022 refueling outage would be less than the acceptance criteria for all locations. Although the maximum rate occurred during the most recent inspection, it is likely due to general fluctuations in corrosion rate and not an indication of an increasing trend in corrosion rate. However, in the unlikely case that the corrosion rate is accelerating, the analysis is still acceptable, because the liner plate locations have significant margin, and the submerged portions of the downcomers can continue to perform their intended function (direct drywell atmosphere and steam into the suppression pool), even if a small hole were to form in the submerged portion. Therefore, conducting the required inspections during the spring 2020 refueling outage will not provide an increase in quality or safety commensurate with the increased hardship.
Based on its review, the staff finds it is acceptable for the licensee to defer the required ASME Code,Section XI, IWE-2420(b) inspections of the submerged portions of the suppression pool and downcomers until no later than the spring 2022 refueling outage. The proposed alternative will provide reasonable assurance that the structural integrity and leaktightness of the containment suppression pool liner and downcomers will be maintained until the next scheduled refueling outage, when the required ASME Code inspections will be completed.
4.0 CONCLUSION
As set forth above, the NRC staff determines 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 the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, the NRC staff authorizes the proposed alternative at Limerick, Unit 1, for the first period of the third 10-year IWE ISI interval.
All other ASME Code,Section XI requirements for which the alternative was not specifically requested and authorized in this proposed alternative remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: B. Lehman M. Mitchell Date: April 20, 2020
ML20089A001
- by e-mail OFFICE NRR/DORL/LPL1/PM NRR/DORL/LPL1/LA NRR/DEX/ESEB/BC(A)* NRR/DSS/SCPB/BC*
NAME VSreenivas LRonewicz SKrepel BWittick DATE 04/ /2020 04/13/2020 04/07/2020 04/07/2020 OFFICE NRR/DORL/LPL1/BC* NRR/DORL/LPL1/PM NAME JDanna VSreenivas DATE 04/18/2020 04/20/2020