ML17283A085

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LaSalle, Units 1 and 2 - Issuance of Amendment Nos. 226 and 212 - Revise Technical Specification 5.5.13, Primary Containment Leakage Rate Testing Program, for Permanent Extension of Leak Rate Test Frequencies (CAC MF8700 and MF8701; L-2016-
ML17283A085
Person / Time
Site: LaSalle  Constellation icon.png
Issue date: 11/16/2017
From: Bhalchandra Vaidya
Plant Licensing Branch III
To: Bryan Hanson
Exelon Generation Co, Exelon Nuclear
Vaidya B K, NRR/DORL/LPLIII
References
CAC MF8700, CAC MF8701, EPID L-2016-LLA-0021
Download: ML17283A085 (50)
v • d • e


Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 November 16, 2017 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:

LASALLE COUNTY STATION, UNITS 1 AND 2 -ISSUANCE OF AMENDMENTS RE: REVISION OF TECHNICAL SPECIFICATIONS 5.5.13, "PRIMARY CONTAINMENT LEAKAGE RATE TESTING PROGRAM," FOR PERMANENT EXTENSION OF TYPE A AND TYPE C LEAK RATE TEST FREQUENCIES (CAC NOS. MF8700 AND MF8701; EPID L-2016-LLA-0021)

Dear Mr. Hanson:

The U.S. Nuclear Regulatory Commission (NRC or Commission) has issued the enclosed Amendment No. 226 to Renewed Facility Operating License No. NPF-11 and Amendment No. 212 to Renewed Facility Operating License No. NPF-18 for the LaSalle County Station (LSCS), Units 1 and 2, respectively.

The amendments revise the licensing basis in response to your application dated October 26, 2016 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML 16300A200), as supplemented by letters dated February 16, July 17, August 8, September 2, October 3, and November 8, 2017 (ADAMS Accession No. ML17048A255, ML17200C944, ML17220A168, ML17270A274, ML17277A219, and ML 173128441, respectively).

The amendments revise Technical Specification 5.5.13, "Primary Containment Leakage Rate Testing Program," to allow for the permanent extension of the Type A Integrated Leak Rate Testing and Type C Leak Rate Testing frequencies, to change the documents used by LSCS to implement the performance-based leakage testing program, and to delete the information regarding the performance of the next LSCS Type A tests to be performed.

Additionally, the amendments delete Conditions 2.D.(e) and 2.D.(c), respectively, of the LSCS Units 1 and 2 Renewed Facility Operating Licenses regarding conducting the third Type A test of each 10-year service period when the plant is shut down for the 10-year inservice inspection.

B. Hanson A copy of the Safety Evaluation is also enclosed.

A Notice of Issuance will be included in the Commission's biweekly Federal Register notice. Docket Nos. 50-373 and 50-37 4

Enclosures:

1. Amendment No. 226 to NPF-11 2. Amendment No. 212 to NPF-18 3. Safety Evaluation cc: Listserv Sincerely, ,~<k -~ Bhalchandra K. Vaidya, Project Manager Plant Licensing Branch Ill Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 EXELON GENERATION COMPANY, LLC DOCKET NO. 50-373 LASALLE COUNTY STATION, UNIT 1 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 226 Renewed License No. NPF-11 1. The U.S. Nuclear Regulatory Commission (the Commission) has found that: A. The application for amendment filed by the Exelon Generation Company, LLC (the licensee), dated October 26, 2016, as supplemented by letters dated February 16, July 17, August 8, September 2, October 3, and November 8, 2017, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's regulations set forth in 10 CFR Chapter I; B. The facility will operate in conformity with the application, the provisions of the Act, and the regulations of the Commission; C. There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations set forth in 1 O CFR Chapter I; D. The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E. The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.

Enclosure 1 2. Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment and paragraph 2.C.(2) of the Renewed Facility Operating License No. NPF-11 is hereby amended to read as follows: (2) Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A, as revised through Amendment No. 226, and the Environmental Protection Plan contained in Appendix B, are hereby incorporated in the renewed license. The licensee shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan. In addition, the license is amended by changes as indicated in the attachment to this license amendment, and paragraph 2.D.(e) of the Renewed Facility Operating License No. NPF-11 is hereby amended to read as follows: (e) DELETED 3. This license amendment is effective as of the date of its issuance and shall be implemented within 60 days from the date of issuance.

FOR THE NUCLEAR REGULATORY COMMISSION David J. Wrona, Chief Plant Licensing Branch Ill Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Date of Issuance:

November 1 6 , 2 O 1 7

Attachment:

Revised License and Technical Specification Pages UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 EXELON GENERATION COMPANY, LLC DOCKET NO. 50-374 LASALLE COUNTY STATION, UNIT 2 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 212 Renewed License No. NPF-18 1. The U.S. Nuclear Regulatory Commission (the Commission) has found that: A. The application for amendment filed by the Exelon Generation Company, LLC (the licensee), dated October 26, 2016, as supplemented by letters dated February 16, July 17, August 8, September 2, October 3, and November 8, 2017, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's regulations set forth in 10 CFR Chapter I; B. The facility will operate in conformity with the application, the provisions of the Act, and the regulations of the Commission; C. There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations set forth in 1 O CFR Chapter I; D. The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E. The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.

Enclosure 2 2. Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment and paragraph 2.C.(2) of the Renewed Facility Operating License No. NPF-18 is hereby amended to read as follows: (2) Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A, as revised through Amendment No. 212, and the Environmental Protection Plan contained in Appendix B, are hereby incorporated in the renewed license. The licensee shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan. In addition, the license is amended by changes as indicated in the attachment to this license amendment, and paragraph 2.D.(c) of the Renewed Facility Operating License No. NPF-18 is hereby amended to read as follows: (c) DELETED 3. This license amendment is effective as of the date of its issuance and shall be implemented within 60 days from the date of issuance.

FOR THE NUCLEAR REGULATORY COMMISSION David J. Wrona, Chief Plant Licensing Branch Ill Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Date of Issuance:

November 1 6, 2 O 1 7

Attachment:

Revised License and Technical Specification Pages ATTACHMENT TO LICENSE AMENDMENT NOS. 226 AND 212 RENEWED FACILITY OPERATING LICENSE NOS. NPF-11 AND NPF-18 DOCKET NOS. 50-373 AND 50-374 Replace the following pages of the Renewed Facility Operating Licenses and Appendix A, Technical Specifications pages, with the enclosed pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change. Remove License NPF-11, Page 3 NPF-11, Page 10 NPF-18, Page 3 NPF-18, Page 10 TS Pages TS 5.5-12 TS 5.5-13 License NPF-11, Page 3 NPF-11, Page 10 NPF-18, Page 3 NPF-18, Page 10 TS Pages TS 5.5-12 TS 5.5-13

Programs and Manuals 5.5 5.5 Programs and Manuals 5.5.12 5.5.13 Safety Function Determination Program CSFDP) (continued)

b. A loss of safety function exists when, assuming no concurrent single failure, and assuming no concurrent loss of offsite power or loss of onsite diesel generator(s), a safety function assumed in the accident analysis cannot be performed.

For the purpose of this program, a loss of safety function may exist when a support system is inoperable, and: 1. A required system redundant to system(s) supported by the inoperable support system is also inoperable; or 2. A required system redundant to system(s) in turn supported by the inoperable supported system is also inoperable; or 3. A required system redundant to support system(s) for the supported systems described in b.l and b.2 above is also inoperable.

c. The SFDP identifies where a loss of safety function exists. If a loss of safety function is determined to exist by this program, the appropriate Conditions and Required Actions of the LCO in which the loss of safety function exists are required to be entered. When a loss of safety function is caused by the inoperability of a single Technical Specification support system, the appropriate Conditions and Required Actions to enter are those of the support system. Primary Containment Leakage Rate Testing Program a. This program shall establish the leakage rate testing of the primary containment as required by 10 CFR 50.54(0) and 10 CFR 50, Appendix, J, Option B, as modified by approved exemptions.

This program shall be in accordance with the guidelines contained in NEI 94-01, "Industry Guideline for Implementing Performance-Based Option of 10 CFR 50, Appendix J," Revision 3-A, dated July 2012, and the conditions and limitations specified in NEI 94-01, Revision 2-A, dated October 2008, as modified by the following exception: (continued)

LaSalle 1 and 2 5.5-12 Amendment No. 226/212 Programs and Manuals 5.5 5.5 Programs and Manuals 5.5.13 Primary Containment Leakage Rate Testing Program (continued)

1. The potential valve atmospheric leakage paths that are not exposed to reverse direction test pressure shall be tested during the regularly scheduled Type A test. The program shall contain the list of the potential valve atmospheric leakage paths, leakage rate measurement method, and acceptance criteria.

This exception shall be applicable only to valves that are not isolable from the primary containment free air space. b. The peak calculated primary containment internal pressure for the design basis loss of coolant accident, Pa, is 42.6 psig. c. The maximum allowable primary containment leakage rate, La, at Pa, is 1.0% of primary containment air weight per day. d. Leakage rate acceptance criteria are: 1. Primary containment overall leakage rate acceptance criterion is~ 1.0 La. During the first unit startup following testing in accordance with this program, the leakage rate acceptance criteria are~ 0.60 La for the combined Type Band Type C tests, and~ 0.75 La for Type A tests. 2. Air lock testing acceptance criteria are: a) Overall air lock leakage rate is~ 0.05 La when tested at Pa. b) For each door, the seal leakage rate is~ 5 scf per hour when the gap between the door seals is pressurized to~ 10 psig. e. The provisions of SR 3.0.3 are applicable to the Primary Containment Leakage Rate Testing Program. (continued)

LaSalle 1 and 2 5.5-13 Amendment No. 22sn12 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 226 TO RENEWED FACILITY OPERATING LICENSE NO. NPF-11 AND AMENDMENT NO. 212 TO RENEWED FACILITY OPERATING LICENSE NO. NPF-18 EXELON GENERATION COMPANY, LLC LASALLE COUNTY STATION, UNITS 1 AND 2 DOCKET NOS. 50-373 AND 50-37 4

1.0 INTRODUCTION

By application dated October 26, 2016 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML 16300A200), as supplemented by letters dated February 16, July 17, August 8, September 2, October 3, and November 8, 2017 (ADAMS Accession No. ML 17048A255, ML 17200C944, ML 17220A168, ML 17270A274, ML 17277A219, and ML 17312B441, respectively), Exelon Generation Company, LLC (EGC or the licensee), requested changes to the licensing bases for the LaSalle County Station (LSCS), Units 1 and 2. The proposed amendments revise Technical Specification

{TS) 5.5.13, "Primary Containment Leakage Rate Testing Program," to allow for the permanent extension of the Type A Integrated Leak Rate Testing (ILRT) and Type C Leak Rate Testing frequencies, to change the documents used by LSCS to implement the performance-based leakage testing program, and to delete the information regarding the performance of the next LSCS Type A tests to be performed.

Additionally, the amendments delete Conditions 2.D.(e) and 2.D.(c), respectively, of the LSCS Units 1 and 2 Renewed Facility Operating Licenses regarding conducting the third Type A Test of each 10-year service period when the plant is shut down for the 10-year inservice inspection (ISi). The supplemental letters dated February 16, July 17, August 8, September 27, October 3, and November 8, 2017, provided additional information that clarified the application, did not expand the scope of the application as originally noticed, and did not change the U.S. Nuclear Regulatory Commission (NRC) staff's original proposed no significant hazards consideration determination as published in the Federal Register on February 14, 2017 (82 FR 10597). Enclosure 3 1.1 Background The license amendment request (LAR) proposes changes to TS 5.5.13, "Primary Containment Leakage Rate Testing Program," consistent with Nuclear Energy Institute (NEI) 94-01, Revision 3-A, "Industry Guideline for Implementing Performance-Based Option of 1 O CFR [Title 1 O of the Code of Federal Regulations]

Part 50, Appendix J," July 2012 (ADAMS Accession No. ML 12221 A202)," and the conditions and limitations specified in NEI 94-01, Revision 2-A, October 2008 (ADAMS Accession No. ML 100620847).

The proposed changes would allow the maximum interval for the ILRT to extend permanently from once in 10 years to once in 15 years. The LAR also proposes to extend the maximum primary containment isolation valve local leakage rate test (LLRT) frequency from 60 months to 75 months. Consistent with the guidance in NEI 94-01, Revision 3-A, and the limitations and conditions for NEI Technical Report (TR) 94-01, Revision 2-A, the proposed changes would permit the performance-based primary containment ILRT, also known as a Type A test, maximum interval to be extended from no longer than 1 O years to no longer than 15 years, provided acceptable performance history and other requirements stated in the report are maintained.

Consistent with NEI 94-01, Revision 3-A, the proposed change would also permit the maximum interval for containment isolation valve LLRTs, also known as Type C tests, to be extended from 60 to 75 months. The licensee justified the proposed TS changes by providing historical plant-specific containment leakage testing program results and containment in-service inspection (GISI) program results and a supporting plant-specific risk assessment, consistent with the guidance in NEI 94-01, Revision 3-A, and the conditions and limitations contained in NEI 94-01, Revision 2-A. The NRC staff reviewed this LAR and provides the following evaluation regarding the acceptability of the requested changes for continued assurance that containment leak-tight integrity will be maintained.

The LAR also requests to extend the Type C local leak rate test interval up to 75 months. Section 3.8 of this safety evaluation (SE) addresses the review of the GISI results, related operating experience, and historical plant-specific containment leakage test results at LSCS to determine a basis to support the requested extension of the Type A test interval.

Section 3.9 of this SE provides the NRC staff evaluation of the licensee's risk assessment.

2.0 REGULATORY EVALUATION

The NRC staff has used the following documents to determine the acceptability of this LAR:

  • The regulation under 1 O CFR Part 50.54(0) requires primary reactor containments for water cooled power reactors be subject to the requirements set forth in Appendix J to 1 O CFR 50, "Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors." Appendix J includes two options: "Option A -Prescriptive Requirements," and "Option B -Performance-Based Requirements," either of which may be chosen by a licensee for meeting the requirements of the Appendix.

Until October 26, 1995, the only option available was the "Prescriptive Requirements." The testing requirements in 1 O CFR Part 50, Appendix J ensure that leakage through containments or systems and components penetrating containments does not exceed allowable leakage rates specified in the TSs, and that integrity of the containment structure is maintained during the service life of the containment. The licensee requested to adopt Option B for meeting the testing requirements of Appendix J, and the NRC staff has issued the associated amendments (Amendment No. 110 for Unit 1 and Amendment No. 95 for Unit 2) by letter dated March 11, 1996 (ADAMS Accession No. ML021130158).

The regulation under 10 CFR Part 50, Appendix J, Option B specifies performance-based requirements and criteria for preoperational and subsequent leakage rate testing. These requirements are met by: (1) performance of Type A tests to measure the containment system overall integrated leakage rate; (2) Type B pneumatic tests to detect and measure local leakage rates across pressure-retaining leakage-limiting boundaries such as penetrations; and (3) Type C pneumatic tests to measure containment isolation valve leakage rates. After the preoperational tests, these tests are required to be conducted at periodic intervals based on the historical performance of the overall containment system (for Type A tests), and based on the safety significance and historical performance of each penetration boundary and isolation valve (for Type Band C tests) to ensure integrity of the overall containment system as a barrier to fission product release. The leakage rate test results must not exceed the maximum allowable leakage rate (La) with margin, as specified in the TSs.

Pa, is 1.0% of primary containment air weight per day." The TS also provides the leakage rate acceptance criteria for the Type A, and Type Band Type C tests stating, in part, that "[p]rimary containment overall leakage rate acceptance criterion is~ 1.0 La. During the first unit startup following testing in accordance with this program, the leakage rate acceptance criteria are 0.60 La for the combined Type B and Type C tests, and 0. 75 La for Type A tests." Option B also requires that a general visual inspection of the accessible interior and exterior surfaces of the containment system, for structural deterioration which may affect the containment leak-tight integrity, must be conducted prior to each Type A test and at a periodic interval between tests.

  • Section V.8.3 of 1 O CFR 50, Appendix J, Option B, requires that the regulatory guide or other implementation document used by a licensee to develop a performance-based leakage testing program must be included, by general reference, in the plant TSs. Furthermore, the submittal for TS revisions must contain justification, including supporting analyses, if the licensee chooses to deviate from methods approved by the Commission and endorsed in a regulatory guide.
  • Revisions 2 and 3 of NEI 94-01 have been reviewed by the NRC and approved for use. The final SE for Revision 2, issued by letter dated June 25, 2008 (ADAMS Accession No. ML081140105), states that NEI 94-01, Revision 2 describes an acceptable approach for implementing the optional performance-based requirements of 1 O CFR 50, Appendix J, Option B. Revision 2 of NEI 94-01 incorporates the regulatory positions stated in NRC Regulatory Guide (RG) 1.163, "Performance-Based Containment Leak-Test Program," September 1995 (ADAMS Accession No. ML003740058), and includes provisions for extending Type A intervals up to 15 years. The NRC staff concluded that NEI 94-01, Revision 2, is acceptable for referencing by licensees proposing to amend their containment leakage rate testing TSs, subject to six specific limitations and conditions listed in Section 4.1 of the NRC staff's SE for NEI 94-01 Revision 2. The final approved version, NEI 94-01, Revision 2-A, was published on November 19, 2008, and includes the NRC staff's SE. The NRC staff's assessment of the six limits and conditions for this amendment request are discussed in Section 3.4 of this SE.
  • Revision 3 of NEI 94-01 provides guidance for extending Type C local leak test (LLRT) intervals beyond 60 months. The NRC found NEI 94-01, Revision 3, acceptable for referencing in licensee application as documented in the final SE dated June 8, 2012 (ADAMS Accession No. ML 121030286), subject to two specific limitations and conditions listed in Section 4.0 of the SE. The final approved version, NEI 94-01, Revision 3-A, was published in July 2012 and includes the NRC staff's SE. The NRC staff's assessment of the two limits and conditions for this amendment request are discussed in Section 3.5 of this SE.
  • The regulation under 1 O CFR 50.55a, "Codes and standards," contains the GISI program requirements that, in conjunction with the requirements of Appendix J, ensure the continued leak-tight and structural integrity of the containment during its service life.
  • The regulation under 10 CFR 50.65(a), "Requirements for monitoring the effectiveness of maintenance at nuclear power plants," states, in part, that the licensee "shall monitor the performance or condition of structures, systems, or components, against licensee-established goals, in a manner sufficient to provide reasonable assurance that these structures, systems, and components, as defined in paragraph (b) of this section, are capable of fulfilling their intended functions.

These goals shall be established commensurate with safety and, where practical, take into account industry wide operating experience."

  • The regulation under 10 CFR 50.36, "Technical specifications," states that the TSs include items in five specific categories.

These categories include: (1) safety limits, limiting safety system settings, and limiting control settings; (2) limiting conditions for operation; (3) surveillance requirements (SRs); (4) design features; and (5) administrative controls.

  • Revision 4 of NUREG-1434, "Standard Technical Specifications

-General Electric BWR/6 Plants," April 2012 (ADAMS Accession No. ML 12104A 195), incorporated the Standard Technical Specification Task Force (TSTF) Traveler TSTF-52, Revision 3, "Implement 1 O CFR 50, Appendix J, Option B" (ADAMS Accession No. ML040400371

), that provided guidance for specific changes to TS for implementation of 10 CFR 50, Appendix J, Option B. 3.0 TECHNICAL EVALUATION Description of Containment and Plant Systems LSCS Units 1 and 2 are of General Electric boiling-water reactor (BWR) design with a Mark 2 pressure suppression containment system consisting of a drywell and a vapor suppression chamber. The primary containment is a concrete structure with the exception of the steel dome head (also called drywell head) and the access penetrations, which are fabricated from steel. The inner surface of the concrete containment is lined with steel plate which acts as a leak-tight membrane.

All liner joints have full penetration welds. The suppression system is of the over-and-under configuration.

The drywell, in the form of a truncated cone having a base diameter of 83 feet (ft), top diameter of 32 ft, and a height of 81 ft. The drywell is located directly above the suppression chamber. The suppression chamber is cylindrical with an inside diameter of 87 ft with a height of 60 ft, separated from the drywell by a reinforced concrete slab. The suppression chamber contains a large amount of water to rapidly condense steam from reactor vessel blowdown or from a break in a major pipe. The floor of the drywell serves both as a pressure barrier between the drywell and suppression chamber and as the support structure for the reactor pedestal and 98 vertical vents, also referred to as downcomer pipes. The downcomer pipes run from above the drywell floor to below the low water level in the suppression pool, to channel steam release from a loss-of-coolant accident for condensation in the suppression chamber. The entire suppression chamber is lined with stainless steel plate. The drywell is provided with an equipment hatch for moving equipment during maintenance and an airlock for entry of personnel into the drywell. During normal plant operations, the equipment hatch is kept sealed and opened only when the plant is shut down for refueling and/or maintenance.

There are two 36-inch diameter openings for access into the suppression chamber for inspection, which are kept closed during normal plant operation and opened only when the plant is shut down for refueling and/or maintenance.

In addition, both the suppression chamber and drywell contain a number of penetrations for pipes, electrical conductors, access for fuel handling and fuel transfer, etc. The primary containment provides the "leak-tight" barrier against the potential uncontrolled release of fission products during a design basis loss-of-coolant accident.

The LSCS TS 5.5.13, "Primary Containment Leakage Rate Testing Program," identifies the primary containment leak rate testing requirements and an overall acceptance criterion for the Type A, Type B, and Type C tests. The proposed changes in consideration apply to primary containment leakage. The drywell-to-suppression chamber bypass leakage test (DWBT) measures the total leakage potential between the drywell airspace and the suppression chamber airspace including the leakage through the four suppression chamber-drywell vacuum breakers.

The LSCS SR 3.6.1.1.3 verifies that the total drywell-to-suppression leakage potential is within the acceptance limit, conducted at a frequency controlled under the LSCS Surveillance Frequency Control Program (SFCP) and therefore, changes to the DWBT frequency do not require prior NRC review and approval.

The DWBT is historically associated with the ILRT frequency for logistical reasons (e.g., similarity of plant line-ups, same equipment for testing).

The licensee stated that DWBT frequency under the SFCP will be revised to once every 15 years following the NRC staff approval of this LAR, and included past DWBT results and a risk assessment in support of this change. However, no TS changes would be required if the licensee proceeds with a change to the DBLRT frequency.

Therefore, the NRC staff did not review the supporting deterministic and risk assessment provided in the LAR. 3.1 Licensee's Proposed Changes 3.1.1 Changes to License Conditions The Unit 1 Renewed Facility Operating License No. NPF-11, Condition 2.D.(e) currently states: An exemption from the requirement of paragraph 111.D of Appendix J to conduct the third Type A test of each ten-year service period when the plant is shutdown for the 10-year plant inservice inspections.

Exemption ( e) is described in the safety evaluation accompanying amendment No. 102 to this License. The Unit 2 Renewed Facility Operating License No. NPF-18, Condition 2.D.(c) currently states: An exemption from the requirement of paragraph 111.D of Appendix J to conduct the third Type A test of each ten-year service period when the plant is shutdown for the 10-year plant inservice inspections.

The licensee is proposing to delete both of the above Conditions, in their entirety, from the respective Renewed Facility Operating Licenses for Unit 1 and Unit 2. 3.1.2 Technical Specifications The LSCS Unit 1 and Unit 2 TS 5.5.13, "Primary Containment Leakage Rate Testing Program," currently states: a. This program shall establish the leakage rate testing of the primary containment as required by 10 CFR 50.54(0) and 1 O CFR 50, Appendix, J, Option B, as modified by approved exemptions.

This program shall be in accordance with the guidelines contained in Regulatory Guide 1.163, "Performance-Based Containment Leak-Testing Program," dated September 1995 as modified by the following exceptions:

1. NEI 94-01 -1995, Section 9.2.3: The first Unit 1 Type A test performed after June 14, 1994 Type A test shall be performed no later than June 13, 2009. 2. NEI 94-01 -1995, Section 9.2.3: The first Unit 2 Type A test performed after December 8, 1993 Type A test shall be performed prior to startup following L2R 12. 3. The potential valve atmospheric leakage paths that are not exposed to reverse direction test pressure shall be tested during the regularly scheduled Type A test. The program shall contain the list of the potential valve atmospheric leakage paths, leakage rate measurement method, and acceptance criteria.

This exception shall be applicable only to valves that are not isolable from the primary containment free air space. b. The peak calculated primary containment internal pressure for the design basis loss of coolant accident, Pa, is 42.6 psig. c. The maximum allowable primary containment leakage rate, La, at Pa, is 1.0% of the containment air weight per day. d. Leakage rate acceptance criteria are: 1. Primary containment overall leakage rate acceptance criterion is s 1.0 La. During the first unit startup following testing in accordance with this program, the leakage rate acceptance criteria are s 0.60 La for the combined Type B and Type C tests, ands 0.75 La for Type A tests. 2. Air lock testing acceptance criteria are: a) Overall air lock leakage rate is s 0.05 La when tested at .:: Pa. b) For each door, the seal leakage rate is s 5 scf per hour when the gap between door seals is pressurized to 2: 10 psig. e. The provisions of SR 3.0.3 are applicable to the Primary Containment Leakage Rate Testing Program. The proposed change modifies the first paragraph of TS 5.5.13.a, deletes exceptions stated under items a.1 and a.2, retains item a.3 with its designation

'3' removed as it would be the sole exception left under TS 5.5.13.a.

The revised TS 5.5.13.a is as follows (additions shown in bold and italic, deletions shown in strikeout text) (remaining portion of TS 5.5.13 is unchanged):

a. This program shall establish the leakage rate testing of the primary containment as required by 1 O CFR 50.54(0) and 10 CFR 50, Appendix, J, Option B, as modified by approved exemptions.

This program shall be in accordance with the guidelines contained in Regulatory Guide 1.163, "Performanoe Based Containment Leak Test Program," dated September 1995, NE/ 94-01, "Industry Guideline for Implementing Performance-Based Option of 1 O CFR 50, Appendix J," Revision 3-A, dated July 2012, and the conditions and limitations specified in NE/ 94-01, Revision 2-A, dated October 2008, as modified by the following exceptions:

1. NEI 94 01 1995, Seotion 9.2.3: The first Unit 1 Type/\. test performed after June 14, 1994 Type /\. test shall be performed no later than June 13, 2009. 2. NEI 94 01 1995, Section 9.2.3: The first Unit 2 Type /\. test performed after December 8, 1993 Type /\. test shall be performed prior to startup follovving L2R12. &.-1. The potential valve atmospheric leakage paths that are not exposed to reverse direction test pressure shall be tested during the regularly scheduled Type A test. The program shall contain the list of the potential valve atmospheric leakage paths, leakage rate measurement method, and acceptance criteria.

This exception shall be applicable only to valves that are not isolable from the primary containment free air space. With this change, LSCS Unit 1 and Unit 2 will implement NEI 94-01, Revision 3-A, and the limitations and conditions of Section 4.1 of the SE for NEI 94-01, Revision 2-A. Revision 3-A of NEI 94-01 provides that extension of the Type A test interval to 15 years be based on two consecutive successful Type A tests (performance history) and other requirements stated in Section 9.2.3 in NEI 94-01. The basis for acceptability of extending the Type A test interval also includes implementation of robust Type B and Type C testing of the penetration barriers, where most containment leakage has historically been shown to occur and are expected to continue to be the pathways for a majority of potential primary containment leakage; and of a robust containment visual inspection program where deterioration of the primary containment boundary away from penetrations can be detected and remediated before any actual significant leakage potential can occur. Revision 3-A of NEI 94-01 also provides that a maximum interval of 120 months could be allowed for Type B tests and a maximum interval of 75 months allowed for Type C tests with a limited provision for extension or grace period up to 9 months allowed for these LLRT. By Amendment Nos. 162 for LSCS Unit 1 and 148 for LSCS Unit 2 issued on November 19, 2003, the NRG approved a one-time TS change to TS 5.5.13, "Primary Containment Leakage Rate Testing Program," to allow a one-time deferral of the primary containment Type A test from 10 years to 15 years. Based on the approval, the licensee performed the last Type A tests for LSCS Unit 1 and Unit 2, in 2008 and 2009, respectively.

Therefore, the accompanying TS 5.5.13 exception to NEI 94-01-1995, Section 9.2.3, denoted by TS 5.5.13, a.1 and a.2, regarding a next Type A test performance for Units 1 and 2, are no longer necessary as that date has passed with the tests having been completed in 2008 for Unit 1 and 2009 for Unit 2. The proposed change under consideration is requesting a permanent change in the frequency of the Type A tests from 10 to 15 years. The reference to RG 1.163 is to be replaced with a reference to NEI 94-01, Revision 3-A, and the Conditions and Limitations of NEI 94-01 Revision 2-A. This is allowed by the provision in 1 O CFR 50, Appendix J, Option B,Section V.B.3 regarding the TS referencing the NRG staff approved guidance document for program implementation. 3.2 Historical Type A Test (ILRT) Results 3.2.1 Unit 1 In LAR Table 3.2.5-1, "LSCS Unit 1 Type A Test History," the licensee presented the historical results of the Type A ILRT tests. The results are summarized in Table 3.2-1 below: Table 3.2-1, LSCS Unit 1 Type A ILRT History As-Found Leakage Acceptance As-Left Leakage Acceptance Rate Criteria(3 l, La Rate Criteria(3l, 0.75La (Containment air (Containment air (Containment air (Containment air Test Date weight %/day weight %/day) weight %/day) weight %/day) 5/14/1982 (4) 0.635 (6) 0.47625 6/4/1986 (4) 0.635 (6) 0.47625 12/23/1989 (4) 0.635 (6) 0.47625 1/14/1993 (4) 0.635 (6) 0.47625 6/14/1994 0.266(5) 0.635 0.202 0.47625 2008 (L 1R12) 0.4 7044(1 H 2 H 5) 0.635 0.47044 0.47625 (1) Test pressure is 42.48 psig. At the time of the test, calculated peak containment accident pressure, Pa, in TS 5.5.13 is 39.9 psig. (2) Subsequent to the ILRT in 2008, TS 5.5.13 was revised by Amendment No. 212 in 2015 to increase Pa from 39.9 psig to 42.6 psig to resolve issues related to non-conservative Pa value in the TSs. (3) Maximum allowable leakage rate, La, is 0.635 of primary containment air weight per day until the 2008 ILRT. Therefore, acceptance limit for as-left leakage rate is 0.47625 (i.e., 0.75 x 0.635). Subsequent to the ILRT in 2008, TS 5.5.13 was revised by Amendment No. 197 in 2010 to increase La from 0.635 to 1.0 of primary containment air weight per day as a result of the implementation of alternate source methodology for accident analyses.

Thus, the acceptance limit for as-left leakage rate became 0.75 (i.e., 0.75 x 1) of primary containment air weight per day. (4) Specific values provided in the LAR were later withdrawn by EGG letter dated September 27, 2017. However, EGG stated that acceptance criterion was met. (5) Provided in EGG letter dated February 16, 2017, and confirmed by EGG letter dated September 27, 2017. (6) Not available as not provided in the LAR. The LAR provided historical results of the two most recent ILRTs. All the results show margins to La. Option B does not allow reduced pressure Type A tests. Section 9.2.3, "Extended Test Intervals," of NEI 94-01, Revision 2-A states, in part, that "in the event where previous Type A tests were performed at reduced pressure (as described in 10 CFR 50, Appendix J, Option A), at least one of the two of the two consecutive periodic Type A tests shall be performed at peak accident pressure (Pa)." In its July 17, 2017, response to the NRC staff's request for additional information (RAI) dated June 15, 2017 (ADAMS Accession No. ML 17164A 115), the licensee stated that the test pressure employed during the most recent Type A test in 2008 is 42.48 psig. The test pressure exceeds Pa value of 39.9 psig that existed in TS 5.5.13 at the time of the test. The NEI 94-01 Revision 3-A requirement for allowing the extended test interval is that the past two tests meet the performance criterion, demonstrating a leakage of La or less. The 1993 and 2009 ILRT results indicate leakage less than the allowable performance criterion, 0.635 weight % per day with As-Found minimum leakages of 0.266 and 0.4044 weight % per day. The staff notes that the test pressure employed during the most recent test in 2008 is slightly below current Pa value of 42.6 psig in TS 5.5.13. This condition was evaluated in the NRC staff's SE issued with Amendment No. 212 dated January 29, 2015 (ADAMS Accession No. ML 14353A083), and found to be acceptable.

The basis for the acceptance was that any increase in Type A leakage due to the higher Pa is very small and that the overall leakage would still remain below the acceptance criteria.

The NRG staff concludes that an extension of approximately 5 years to the next ILRT is also justified based on the same considerations in the staff's SE issued with Amendment No. 212. 3.2.2 Unit 2 In LAR Table 3.2.5-2, "LSGS Unit 2 Type A Test History," the licensee presented the historical results of the Type A ILRT tests. The results are summarized in Table 3.2-2 below: Table 3.2-2, LSCS Unit 2 Type A ILRT History As-Found Leakage Acceptance As-Left Leakage Acceptance Rate Criteria(3), La Rate Criteria(3), 0.75La (Containment air (Containment air (Containment air (Containment air Test Date weight %/day weight %/day) weight %/day) weight %/day) 6/24/1983 (4) 0.635 (7) 0.47625 6/1/1987 (4) 0.635 (7) 0.47625 6/3/1990 (5) 0.635 (7) 0.47625 3/28/1992 (4) 0.635 (7) 0.47625 12/8/1993 0.4273(6) 0.635 0.3164(6) 0.47625 2009 (L2R12) 0.3863(1)(2)(5) 0.635 0.3863(6) 0.47625 (1) Test pressure is 41.26 psig. At the time of the test, calculated peak containment accident pressure, Pa, in TS 5.5.13 is 39.9 psig. (2) Subsequent to the ILRT in 2008, TS 5.5.13 was revised by Amendment No. 198 in 2015 to increase Pa from 39.9 psig to 42.6 psig to resolve issues related to non-conservative Pa value in the TSs. (3) Maximum allowable leakage rate, La, is 0.635 of primary containment air weight per day until the 2009 ILRT. Therefore, acceptance limit for as-left leakage rate is 0.47625 (i.e., 0.75 x 0.635). Subsequent to the ILRT in 2009, TS 5.5.13 was revised by Amendment No. 184 in 2010 to increase La from 0.635 to 1.0 of primary containment air weight per day as a result of the implementation of alternate source methodology for accident analyses.

Thus, the acceptance limit for as-left leakage rate became 0.75 (i.e., 0.75 x 1 ). (4) Specific values provided in the LAR were later withdrawn by EGC letter dated September 27, 2017. However, EGC stated that acceptance criterion was met. (5) Results show greater than the acceptance limit of 0.635 wt.%/day as a result of excessive leakage found at a local leak tested penetration or isolation valve. Corrective actions taken with LLRT performed before and after, which resulted in satisfactory As-Left total leakage results. (6) Provided in EGC letter dated February 16, 2017, and confirmed by EGC letter dated September 27, 2017. (7) Not available as not provided in the LAR. The LAR provided historical results of the two most recent ILRTs. All the results show margins to La. Option B does not allow reduced pressure Type A tests. Section 9.2.3, "Extended Test Intervals," of NEI 94-01, Revision 2-A states, in part, that "in the event where previous Type A tests were performed at reduced pressure (as described in 10 GFR 50, Appendix J, Option A), at least one of the two of the two consecutive periodic Type A tests shall be performed at peak accident pressure (Pa)." In its July 17, 2017, response to the NRG staff's RAI dated June 15, 2017, the licensee stated that the test pressure employed during the most recent Type A test in 2008 is 42.48 psig. The test pressure exceeds Pa value of 39.9 psig that existed in TS 5.5.13 at the time of the test. The NEI 94-01 Revision 3-A requirement for allowing the extended test interval is that the past two tests meet the performance criterion, demonstrating a leakage of La or less. The 1993 and 2008 ILRT results indicate leakage less than the allowable performance criterion, 0.635 weight% per day with as-found minimum leakages of 0.4273 and 0.3863 weight% per day, respectively.

The staff notes that the test pressure employed during the most recent test in 2009 is slightly below current Pa value of 42.6 psig in TS 5.5.13. This condition was evaluated in the NRC's SE issued with Amendment No. 198, dated January 29, 2015, and found to be acceptable.

The basis for the acceptance was that any increase in Type A leakage due to the higher Pa is very small and that the overall leakage would still remain below the acceptance criteria.

The NRC staff concludes that an extension of approximately 5 years to the next ILRT is also justified based on the same considerations in the staff's SE issued with Amendment No. 198. 3.2.3 Performance Leakage Rate In the letter dated July 17, 2017, the licensee's response to SBPB RAl-2 provided the definition of "performance leakage rate" used during the historical LSCS ILRTs. The licensee stated that LSCS was approved to incorporate 10 CFR Part 50, Appendix J, Option B by Amendment Nos. 11 O and 95 for LSCS Unit 1 and Unit 2, respectively, dated March 11, 1996. Therefore, all the ILRTs performed prior to the adoption of Appendix J, Option B were not performed under the performance based standard.

The licensee acknowledged that the definition of "performance leakage rate" contained in NEI 94-01 Revision 0, 2-A, and 3-A is different from that of American Nuclear Standards Institute/American Nuclear Society (ANSI/ANS) 56.8-2002, in that it is more inclusive as it considers excessive leakage in the performance determination.

The licensee used the following definition to calculate the 2008 Unit 1 and 2009 Unit 2 ILRT performance leakage rate: The performance criteria for Type A test allowable leakage is less than 1.0 La. This allowable leakage rate is calculated as the sum of the Type A UCL [upper confidence limit] and As-Left MNPLR [minimum pathway leakage rate] leakage rate for all Type B and Type C pathways that were in service, isolated or not lined up in their test position (i.e., drained and vented to containment atmosphere) prior to performing the Type A test. In addition, leakage pathways that were isolated during performance of the test because of excessive leakage must be factored into the performance determination.

If the leakage can be determined by a local leak rate test, the As-Found MNPLR for that leakage path must also be added to the Type A UCL. If the leakage cannot be determined by local leak rate testing, the performance criteria are not met. The NRC staff compared the acceptance criteria with the performance leakage criteria as defined in Section 9.2.3 of NEI 94-01, Revision O, and concluded that they are consistent with each other. The 1994 and 2008 Unit 1, and 2003 and 2009 Unit 2 ILRT test results provided by the licensee in response to SBPB RAl-1 indicate that the leakage includes the sum of the 95 percent UCL, non-vented pathways, isolated pathways, and back-correction for improvements made to the pathways during the outage in advance of the Type A ILRT. Since the last two Type A tests at LSCS Unit 1 and Unit 2 had "As-found" test results of less than 1.0 La, a permanent extension to the test frequency of 15 years in accordance with NEI 94-01, Revision 2-A is acceptable. 3.3 Historical Type Band Type C Test (LLRT) Results 3.3.1 Unit 1 TS 5.5.13, "Primary Containment Leakage Rate Testing Program," states, in part: d. Leakage rate acceptance criteria are: 1. Primary containment overall leakage rate acceptance criterion is :s; 1.0 La. During the first unit startup following testing in accordance with this program, the leakage rate acceptance criteria are :s; 0.60 La for the combined Type Band Type C tests, and :s; 0.75 La for Type A tests. The containment performance is demonstrated by the As-Found minimum pathway summations, whereas the As-Left maximum pathway summations signify the acceptance criteria for restart. The licensee submitted the local leak rate summaries in Table 3.4.5-1, "LSCS Unit 1 Type and Type C LLRT Combined As-Found/As-Left Trend Summary," of Attachment 1 to the LAR. The summary was provided for six refueling outages starting from year 2006 to year 2016. In its letter dated October 3, 2017, EGG modified the tables by stating that the tests in 2006, 2008, and 201 Oare pre-alternate source term (AST) amendment tests and the tests in 2012, 2014, and 2016 are post-AST amendment tests. In addition, EGG stated that the applicable La values are 387.8 standard cubic feet per hour (SCFH) and 640.4 SCFH for the pre-AST and post-AST tests. As noted earlier, La in TS 5.5.13 was 0.635 percent of primary containment air weight per day for pre-AST tests, but later increased to 1.0 percent of primary containment air weight per day for post-AST tests by License Amendment No. 197, which approved AST methodology implementation at LSCS Unit 1. The TS 5.5.13 acceptance criterion for combined Type Band C test total is 0.6 La. In the modified Table 3.4.5-1 of the letter dated October 3, 2017, the licensee provided the As-Found minimum pathway and As-Left maximum pathway leakage rates for the six refueling outages as percent fraction of 0.6 La. With the use of the La values and the data contained in Table 3.4.5-1, the NRG staff confirmed the accuracy of the "Fraction of 0.6 La" values contained in the table. The results show:

  • The Unit 1 "As-Found" minimum pathway leakage rates for the last six refueling outages since 2006 vary from a minimum of 27.15 percent of 0.6 La to a maximum of 52.43 percent of 0.6 La.
  • The Unit 1 "As-Left" maximum pathway leakage rates for the last six refueling outages since 2006 vary from a minimum of 53.72 percent of 0.6 La to a maximum of 80.57 percent of 0.6 La. The results indicate a reasonable amount of margin between the combined Type B and Type C test totals and the performance criterion (0.6 La). The NRG staff noted that there is an uptick in the leakage rates during the 2014 and 2016 refueling outages. However, as a fraction of 0.6 La, the results generally represented the lower end of the spectrum due to the higher allowable leakage as a result of the AST implementation.

In addition, the staff notes that higher leakage rates are not representative of an adverse trend because Option B provides the licensee with greater flexibility in adjusting the evaluation/administrative limits of leakage for Type B and Type C penetrations, while ensuring that the combined Type B and Type C test results remain below the acceptance criterion of 0.6 La. The results suggest that performance criteria are unlikely to be exceeded by use of extended LLRT intervals. In Section 3.4.5 of Attachment 1 to the LAR, Table 3.4.5-3, "LSCS Unit 1 Type B and Type C LLRT Program Implementation Review," identified four components that were on extended test intervals and have not demonstrated acceptable performance during the previous two outages during 2014 (L 1R15) and 2016 (L 1R16). In response to SBPB RAl-4, the licensee provided additional information in its letter dated July 17, 2017. The revised table provided As-Found and As-Left maximum pathway leakage rate (MXPLR) and MNPLR for the components in the four penetrations in LAR Table 3.4.5-3. For penetration M-7, valve 1 E12-F008 failed with As-Found MXPLR of 596 SCFH. The admin limit was 30 SCFH. However, the As-Found MNPLR for the penetration was 0.52 SCFH. The cause of failure is the actuator and the licensee has replaced the actuator with an As-Left MXPLR of 1.05 SCFH. Valve 1 PC002A is a drywell to suppression pool vacuum breaker manual isolation valve with an outboard flange that is not equipped with a locally testable seal. The As-Found MXPLR was 98.5 SCFH with an admin limit of 1 O SCFH. The cause of failure is flange leakage and the corrective action taken is to tighten the flange bolting. The As-Left MXPLR is 12 SCFH. For penetration M-45, 1C51-J004E failed with As-Found MXPLR of 19.8 SCFH. The admin limit is 10 SCFH. The leakage was absorbed into leakage totals for outage L 1R16. The valve is planned for replacement during outage L 1 R17. For penetration M-101, the leakage test is performed between two containment isolation valves 1 E51-F080 and 1 E51-F086.

The administrative limit is 1 O SCFH. A satisfactory leakage test could not be performed due to excessive leakage past 1 E51-F086.

The cause of failure is a valve seating issue. The valve was rebuilt with an As-Found MXPLR of 1.75 SCFH. The As-Left MNPLR for valve 1 E51-F080 is 0.88 SCFH. All the failed components were relegated to 30 month test frequency.

The NRC staff concludes that the licensee has appropriately addressed valves underperforming their administrative criteria in accordance with the Primary Containment Leakage Rate Testing Program and NEI 94-01, Revision 3-A. In a letter dated February 16, 2017, EGC informed the staff that two new primary containment isolation valves are being added to the 1 O CFR 50, Appendix J program at LSCS Unit 1 as a result of NRC Order EA-13-109, "Issuance of Order to Modify Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation under Severe Accident Conditions," dated June 6, 2013 (ADAMS Accession No. ML 13143A321

). This modification will tap into an existing containment penetration located between the suppression pool and drywell and is scheduled for installation during the L 1R17 outage. A local leak rate test will be performed for the affected penetration under administrative control procedure L TS-100-57, with an acceptance criteria below 30 SCFH. Based on the review of the data contained in the modified Table 3.4.5-1 of EGC letter dated October 3, 2017, the NRC staff concludes that the aggregate results of the As-Found/As-Left trend summary for the Type Band Type C tests from 2006 to 2016 demonstrate a history of successful tests. Furthermore, the table shows that there has been no As-Found failures that resulted in exceeding the TS 5.5.13.d acceptance limit of 0.6 La. The As-Found minimum pathway summations represent an acceptable quality of maintenance of Type B and Type C components, while the As-Left minimum pathway summations represent an effective management of the Containment Leakage Rate Testing Program. In its July 17, 2017, response to SBPB RAl-5, the licensee provided statistics on the number of Type B and Type C components that are on extended frequencies of 120 months and 60 months, respectively.

The percentage of the total number of Type Band Type C components that are on extended performance-based test intervals are 91 percent and 65 percent, respectively.

The NRC staff concludes that from the high percentage of Type Band Type C components on extended frequencies represents good performance and further supports the requested changes to TS 5.5.13. 3.3.2 Unit 2 TS 5.5.13, "Primary Containment Leakage Rate Testing Program," states, in part: d. Leakage rate acceptance criteria are: Primary containment overall leakage rate acceptance criterion is s; 1.0 La. During the first unit startup following testing in accordance with this program, the leakage rate acceptance criteria ares; 0.60 La for the combined Type Band Type C tests, ands; 0.75 La for Type A tests. The containment performance is demonstrated by the As-Found minimum pathway summations, whereas the As-Left maximum pathway summations signify the acceptance criteria for restart. The licensee submitted the local leak rate summaries in Table 3.4.5-2, "LSCS Unit 2 Type Band Type C LLRT Combined As-Found/As-Left Trend Summary" of Attachment 1 to the LAR. The summary was provided for six refueling outages starting from year 2005 to year 2015. By letter dated October 3, 2017, EGC modified the tables by stating that the tests in 2006, 2008, and 201 O are pre-AST amendment tests and the tests in 2012, 2014, and 2016 are post-AST tests. In addition EGC stated that the applicable La values are 387.8 SCFH and 640.4 SCFH for the pre-AST and post-AST tests, respectively.

As noted earlier, La in TS 5.5.13 was 0.635% of primary containment air weight per day for pre-AST tests, but later increased to 1.0% of primary containment air weight per day by License Amendment No. 184, which approved AST methodology implementation at LSCS Unit 2. The TS 5.5.13 acceptance criterion for combined Type Band C test total is 0.6 La. In the modified Table 3.4.5-2 contained in the letter dated October 3, 2017, the licensee provided the As-Found minimum pathway and As-Left maximum pathway leakage rates for the six refueling outages as percent fraction of 0.6 La. With the use of the La values and the data contained in Table 3.4.5-2, the NRC staff confirmed the accuracy of the "Fraction of 0.6 La" values contained in the table. The results show:

  • The Unit 2 "As-Found" minimum pathway leakage rates for the last six refueling outages since RFO L2R10 in 2005 vary from a minimum of 24.33 percent of 0.6 La to a maximum of 45.94 percent of 0.6 La.
  • The Unit 2 "As-Left" maximum pathway leakage rates for the last six refueling outages since RFO L2R10 in 2005 vary from a minimum of 39.13 percent of 0.6 La to a maximum of 7 4.42 percent of 0.6 La. The results indicate a reasonable amount of margin between the combined Type B and Type C test totals and the performance criterion (0.6 La). The NRC staff also noted that there is an uptick in the leakage rates during the 2013 and 2015 refueling outages. However, as a fraction of 0.6 La, the results generally represented the lower end of the spectrum due to the higher allowable leakage as a result of the AST methodology implementation.

In addition, the staff notes that higher leakage rates are not representative of an adverse trend because Option B provides the licensee with greater flexibility in adjusting the evaluation/administrative limits of leakage for Type B and Type C penetrations, while ensuring that the combined Type B and Type C test results remain below the acceptance criterion of 0.6 La. The results suggest that performance criteria are unlikely to be exceeded by use of extended LLRT intervals.

In Section 3.4.5 of Attachment 1 to the LAR, Table 3.4.5-4, "LSCS Unit 2 Type Band Type C LLRT Program Implementation Review," identified two components that were on extended test intervals and have not demonstrated acceptable performance during the outage in 2015 (L2R15). There were no administrative failures associated with components on extended intervals during the 2013 outage (L2R14). In its July 17, 2017, response to SBPB RAl-4, the licensee provided additional information by including "As-Found" and "As-Left" maximum and minimum pathway leakage values (i.e., MXPLR and MNPLR, respectively) for the penetrations associated with the two components in LAR Table 3.4.5-4. For penetration M-98, valve 2RF-012 failed with As-Found MXPLR of 17.2 SCFH. The administrative limit was 1 O SCFH. The cause of failure was the valve actuator and the licensee has replaced the actuator with an As-Left MNPLR of 3.62 SCFH. For penetration M-42, 2C51-J004C failed with As-Found MXPLR of 19.8 SCFH. The administrative limit is 1 O SCFH. The leakage was absorbed into leakage totals for outage L2R15. The valve is planned for replacement during outage L2R16. All the failed components were relegated to 30 month test frequency.

The NRC staff concludes that the licensee has appropriately addressed valves underperforming their administrative criteria in accordance with the Primary Containment Leakage Rate Testing Program and NEI 94-01, Revision 3-A. In its letter dated February 16, 2017, EGC informed the NRC staff that two new primary containment isolation valves were added to the 10 CFR 50, Appendix J program at LSCS Unit 2 during refueling outage L2R16 in February 2017, as a result of NRC Order EA-13-109, "Issuance of Order to Modify Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation under Severe Accident Conditions," dated June 6, 2013. This modification tapped into an existing containment penetration M-104 located between the suppression pool and drywell. A local leak rate test was performed for this penetration, administratively controlled by procedure L TS-100-57, "Hardened Containment Isolation Valves Local Leak rate Test 2PC009A and 2PC01 OA," with the acceptance criteria below 30 SCFH. The test results show As-Found MNPLR of 0.655 SCFH and As-Left MXPLR of 1.310 SCFH, significantly below the acceptance limit of 30 SCFH. Based on the review of the data in the modified Table 3.4.5-2 contained in EGC's letter dated October 3, 2017, the NRC staff concludes that the aggregate results of the As-Found/As-Left trend summary for the Type Band Type C tests from 2005 to 2015 demonstrate a history of successful tests. Furthermore, the table shows that there has been no As-Found failures that resulted in exceeding the TS 5.5.13.d acceptance limit of 0.6 La. The As-Found minimum pathway summations represent an acceptable quality of maintenance of Type B and Type C components, while the As-Left minimum pathway summations represent an effective management of the Containment Leakage Rate Testing Program. In its July 17, 2017, response to SBPB RAl-5, the licensee provided statistics on the number of Type B and Type C components that are on extended frequencies of 120 months and 60 months, respectively.

The percentage of the total number of Type B and Type C components that are on extended performance-based test intervals are 88 percent and 59 percent, respectively.

The NRC staff concludes that the percentage of Type Band Type C components on extended frequencies represent a reasonable performance and supports the requested changes to TS 5.5.13. 3.4 NRC Conditions In NEI 94-01, Revision 2-A In its SE dated June 25, 2008, the NRC staff concluded that the guidance in TR NEI 94-01, Revision 2 is acceptable for reference by licensees proposing to amend their TS in regards to containment leakage rate testing, subject to six conditions.

The requirements of NEI 94-01 stayed essentially the same from the original version through Revision 2, except that the regulatory positions of RG 1.163 were incorporated and the maximum ILRT interval extended to 15 years. Industry review and familiarization with these changes were extensive during the NEI 94-01 revision process. The accepted version of NEI 94-01, Revision 2 was subsequently issued as Revision 2-A. However, the SE conditions contained in Revision 2-A were inadvertently left out of NEI 94-01 Revision 3, nor carried forward into the NRC Staff SE for Revision 3. To ensure licensee acknowledge and satisfy the limitations and conditions in the NEI 94-01 Revision 2 SE, the NRC staff evaluated LAR Section 3.8, "NRC Limitations and Conditions," Table 3.8.1.1, "NEI 94-01, Revision 2-A, Limitations and Conditions." Section 3.8 of this SE provides additional discussion of the NRC staff evaluation regarding implementation of Conditions 2, 3, and 4. In Table 3.7.1-1, "NEI 94-01, Revision 2-A, Limitations and Conditions," in Section 3.7.1 of Attachment 1 to the LAR, the licensee provided its response to the limitations and conditions.

NRC Condition 1 For calculating the Type A leakage rate, the licensee should use the definition in the NEI TR 94-01, Revision 2, in lieu of that in ANSI/ANS-56.8-2002. (Refer to SE Section 3.1.1.1.)

LSCS Response Limitation/Condition 1 LSCS will utilize the definition in NEI 94-01 Revision 3-A, Section 5.0. This definition has remained unchanged from Revision 2-A to Revision 3-A of NEI 94-01. NRC Staff Assessment Section 3.2.9, "Type A test performance criterion," of ANSI/ANS-56.8-2002 defines the "performance leakage rate" and states, in part: The performance criterion for a Type A test is met if the performance leakage rate is less than La. The performance leakage rate is equal to the sum of the measured Type A test UCL and the total as-left MNPLR of all Type B or Type C pathways isolated during performance of the Type A test. The NRC staff's SE Section 3.1.1.1, Enclosure Page 6, for NEI 94-01 Revision 2, states, in part: ... Section 5.0 of NEI TR 94-01, Revision 2, uses a definition of "performance leakage rate" for Type A tests that is different from that of ANSI/ANS-56.8-2002.

The definition contained in NEI TR 94-01, Revision 2, is more inclusive because it considers excessive leakage in the performance determination.

In defining the minimum pathway leakage rate, NEI TR 94-01, Revision 2, includes the leakage rate for all Type Band Type C pathways that were in service, isolated, or not lined up in their test position prior to the performance of the Type A test. Additionally, the NEI TR 94-01, Revision 2, definition of performance leakage rate requires consideration of the leakage pathways that were isolated during performance of the test because of excessive leakage in the performance determination.

The NRC staff finds this modification of the definition of "performance leakage rate" used for Type A tests to be acceptable

.... Section 5.0, "Definitions," of NEI 94-01, Revision 2-A states, in part: ... The performance leakage rate is calculated as the sum of the Type A upper confidence limit (UCL) and as-left minimum pathway leakage rate (MNPLR) leakage rate for all Type Band Type C pathways that were inservice, isolated, or not lined up in their test position (i.e., drained and vented to containment atmosphere) prior to performing the Type A test. In addition, leakage pathways that were isolated during performance of the test because of excessive leakage must be factored into the performance determination.

The performance criterion for Type A tests is a performance leak rate of less than 1.0 La. The NRC staff reviewed the definitions of "performance leakage rate" contained in NEI 94-01, Revision 2, Revision 2-A and Revision 3-A. The NRC staff concluded that the definitions contained in all three revisions are identical.

Based on this, the NRC staff agrees with the licensee that the definition has remained unchanged from Revision 2 through Revision 3-A of NEI 94-01. Therefore, the NRC staff concludes that LSCS will use the definition found in Section 5.0 of NEI 94-01, Revision 2 for calculating the Type A leakage rate in the LSCS "Primary Containment Leakage Rate Testing Program." Based on the above review, the NRC staff finds that the licensee has adequately addressed "Condition 1." NRC Condition 2 The licensee submits a schedule of containment inspections to be performed prior to *and between Type A tests. (Refer to SE Section 3.1.1.3.)

LSCS Response Limitation/Condition 2 Reference Sections 3.4.3 and 3.4.4 of the licensee submission dated October 26, 2016, Attachment

1. NRC Staff Assessment Page 12 of NEI 94-01, Revision 3-A, Section 9.2.3.2, "Supplemental Inspection Requirements," states: To provide continuing supplemental means of identifying potential containment degradation, a general visual examination of accessible interior and exterior surfaces of the containment for structural deterioration that may affect the containment leak-tight integrity must be conducted prior to each Type A test and during at least three other outages before the next Type A test if the interval for the Type A test has been extended to 15 years. It is recommended that these inspections be performed in conjunction or coordinated with the ASME [American Society of Mechanical Engineers]

Boiler and Pressure Vessel Code,Section XI, Subsection IWE/IWL required examinations.

The LAR, Section 3.4.3, "Containment lnservice Inspection program," states, in part: The LSCS Containment ISi Plan includes ASME Section GISI Class MC pressure retaining components and their integral attachments, and GISI Class CC components and structures, and post-tensioning systems that meet the criteria of Subarticle IWA-1300.

This Containment ISi Plan also includes information related to augmented examination areas, component accessibility, and examination review. Programmatically, each 10-year GISI interval is divided into three successive inspection periods as determined by calendar year of plant service within the inspection interval.

Based on the information in the LAR, Section 3.4.3, the LSCS Units 1 and 2 first GISI interval was effective from September 9, 1996, through September 30, 2007, and the second GISI interval for LSCS Units 1 and 2 spans from October 1, 2007, to September 30, 2017. The LAR also provided a detailed second GISI interval plan for LSCS Units 1 and 2 in Table 3.4.3-1, "Class MC Component Examinations," Table 3.4.3-2, "Class CC Concrete Component Examinations," and Table 3.4.3-3, "Class CC Tendon Examinations." The LAR further states that LSCS Units 1 and 2 third interval GISI program spanning October 1, 2017, to September 30, 2027, is currently in development.

However, by letter dated November 8, 2017, the licensee submitted a schedule of inspections completed for the second GISI interval and a schedule of inspections planned for the third interval GISI program for LSCS Units 1 and 2. Sections 3.4.1, "Appendix J Primary Containment Inspection," and 3.4.4, "Supplemental Inspection Requirements," of the LAR acknowledges that the proposed TS change requires a general visual examination of accessible interior and exterior surfaces of the containment for structural deterioration that may affect the containment leak-tight integrity.

In addition, the LAR also acknowledges that this inspection must be conducted prior to each Type A test and during at least three outages before the next Type A test if the interval for the Type A test is extended to 15 years in accordance with the guidance in Sections 9.2.1, "Pretest Inspection and Methodology" and 9.2.3.2, "Supplemental Inspection Requirements." The LAR also stated that inspections are required at LSCS to ensure compliance with the visual inspection requirements in the current TS SR 3.6.1.1.1.

In summary, the licensee expects to comply with NEI 94-01, Revision 3-A by a combination of IWE and IWL examinations scheduled in accordance with GISI and the Appendix J Primary Containment Inspection in accordance with the current TS SR 3.6.1.1.1.

In addition, the NRC staff finds that the schedule of inspections provided for the third interval CISI program demonstrates LSCS compliance with the Limitation and Condition 2, including the NRC SE Section 3.1.1.3 in NEI 94-01, Revision 2-A. Therefore, the NRC staff finds that the licensee has addressed and satisfied the NRC Condition

2. NRC Condition 3 The licensee addresses the areas of the containment structure potentially subjected to degradation. (Refer to SE Section 3.1.1.3.)

LSCS Response Limitation/Condition 3 Reference 3.4.3 and Section 3.5 of the licensee submission dated October 26, 2016, Attachment

1. NRC Staff Assessment The NRC staff's SE Section 3.1.3, Enclosure Page 9, for NEI 94-01, Revision 2 states, in part: ... In approving for Type A tests the one-time extension from 10 years to 15 years, the NRC staff has identified areas that need to be specifically addressed during the IWE and IWL inspections including a number of containment pressure-retaining boundary components (e.g., seals and gaskets of mechanical and electrical penetrations, bolting, penetration bellows) and a number of the accessible and inaccessible areas of the containment structures (e.g., moisture barriers, steel shells, and liners backed by concrete, inaccessible areas of ice condenser containments that are potentially subject to corrosion)

.... The LAR Section 3.4.3 states that for Class MC applications, the licensee will evaluate the acceptability of inaccessible in accordance with the requirements in 10 CFR 50.55a(b}(2(ix)(A), when conditions exist in accessible areas that could indicate the presence of or could potentially, result in degradation of such in accessible areas. Metal containment components potentially subject to augmented examination per paragraph IWE-1240 have been evaluated in the containment sections of the ISi Classification Basis Document, which define the areas that are subjected to augmented examination. Concrete surfaces may be subject to Detailed Visual examination in accordance with IWL-2310, if declared to be "Suspect Areas" by the examiner or the Responsible Engineer.

The LAR states that no significant conditions were identified in the first interval as requiring application of additional augmented examination under paragraph IWE-1240 or IWL-2310.

In addition, no significant conditions are currently identified in the second interval.

In addition, LAR Section 3.5, "Operating Experience," indicates that the licensee is proactively evaluating industry events for impact on the LSCS primary containment.

Based on the information contained in Sections 3.4.3 and 3.5 of Attachment 1 to the LAR, the NRC staff finds that the licensee has adequately addressed "Condition 3." NRC Condition 4 The licensee addresses any tests and inspections performed following major modifications to the containment structure, as applicable. (Refer to SE Section 3.1.4.) LSCS Response Limitation/Condition 4 There are no major modifications planned that would require the performance of a Type A ILRT or a Structural Integrity Test (SIT). N RC Staff Assessment The NRC staff's SE Section 3.1.4, Enclosure Page 9, for NEI 94-01 Revision 2, states, in part: Section 9.2.4 of NEI TR 94-01, Revision 2, states that: "Repairs and modifications that affect the containment leakage integrity require LLRT or short duration structural tests as appropriate to provide assurance of containment integrity following the modification or repair. This testing shall be performed prior to returning the containment to operation." Article IWE-5000 of the ASME Code,Section XI, Subsection IWE (up to the 2001 Edition and the 2003 Addenda), would require a Type A test after major repair or modifications to the containment.

In general, the NRC staff considers the cutting of a large hole in the containment for replacement of steam generators or reactor vessel heads, replacement of large penetrations, as major repair or modifications to the containment structure.

This condition is intended to verify any major modification or maintenance repair of the primary since the last ILRT has been appropriately accompanied by a either an SIT or ILRT and that any plans for such major modification also includes appropriate pressure testing. The response in the LAR stated that no major modifications are planned that would require the performance of a Type A ILRT or an SIT. In its July 17, 2017, response to SBPB RAl-3, the licensee stated that no significant modifications requiring post-modification testing have been performed on the primary containments at LSCS Unit 1 or Unit 2 since the 2008 Unit 1 and 2009 Unit 2 ILRTs. The NRC staff concludes that the licensee has adequately addressed Condition

4. NRC Condition 5 The normal Type A test interval should be less than 15 years. If a licensee has to utilize the provision of Section 9.1 of NEI TR 94-01, Revision 2, related to extending the ILRT interval beyond 15 years, the licensee must demonstrate to the NRC staff that it is an unforeseen emergent condition. (Refer to SE Section 3.1.1.2.)

LSCS Response Limitation/Condition 5 LSCS will follow the requirements of NEI 94-01 Revision 3-A, Section 9.1. This requirement has remained unchanged from Revision 2-A to Revision 3-A of NEI 94-01. NRC Staff Assessment The NRC staff's SE Section 3.1.1.2, Enclosure Page 6, for NEI 94-01 Revision 2, states: As noted above, Section 9.2.3, NEI TR 94-01, Revision 2, states, "Type A testing shall be performed during a period of reactor shutdown at a frequency of at least once per 15 years based on acceptable performance history." However, Section 9.1 states that the "required surveillance intervals for recommended Type A testing given in this section may be extended by up to 9 months to accommodate unforeseen emergent conditions but should not be used for routine scheduling and planning purposes." The NRC staff believes that extensions of the performance-based Type A test interval beyond the required 15 years should be infrequent and used only for compelling reasons. Therefore, if a licensee wants to use the provisions of Section 9.1 in TR NEI 94-01, Revision 2, the licensee will have to demonstrate to the NRC staff that an unforeseen emergent condition exists. The LAR response acknowledges and accepts the NRC staff position that extensions of the Type A test interval beyond the upper-bound performance based limit of 15 years should be infrequent and that any request for an extension should demonstrate to the NRC staff that an unforeseen emergent condition exists. Therefore, the licensee addressed and satisfied Condition

5. NRC Condition 6 For plants licensed under 1 O CFR Part 52, applications requesting a permanent extension of the I LRT surveillance interval to 15 years should be deferred until after the construction and testing of containments for that design have been completed and applicants have confirmed the applicability of NEI 94-01, Revision 2, and [Electric Power Research Institute (EPRI)] Report No. 1009325, Revision 2, including the use of past ILRT data. LSCS Response Limitation/Condition 6 Not applicable.

LSCS was not licensed under 10 CFR Part 52. NRC Staff Assessment The NRC staff finds the licensee's response acceptable.

3.5 NRC Conditions In NEI 94-01, Revision 3-A By letter dated June 8, 2012, the NRC published an SE, with limitations and conditions, for NEI 94-01, Revision 3. In the SE, the NRC concluded that NEI 94-01, Revision 3, describes an acceptable approach for implementing the optional performance-based requirements of 10 CFR 50, Appendix J, and is acceptable for referencing by licensees proposing to amend their TS in regards to containment leakage rate testing, subject to the limitations and conditions identified in SE Section 4.0 and summarized in SE Section 5.0. The accepted version of NEI 94-01, Revision 3 was subsequently issued as Revision 3-A. The NEI issued Revision 3-A to NEI 94-01 on July 31, 2012. With Revision 3-A, the report was revised to incorporate the June 8, 2012 NRC final SE. In the SE dated June 25, 2008, the NRC staff concluded that the guidance in TR NEI 94-01, Revision 3 is acceptable for reference by licensees proposing to amend their TSs to extend the Option B to 10 CFR Part 50, Appendix J, Type C test intervals beyond 60 months, provided two conditions are satisfied.

Section 3.7.2, "Limitations and Conditions Applicable to NEI 94-01 Revision 3-A" of Attachment 1 to the LAR addressed LSCS response to the two conditions:

Condition 1 NEI TR 94-01, Revision 3, is requesting that the allowable extended interval for Type C LLRTs be increased to 75 months, with a permissible extension (for non-routine emergent conditions) of nine months (84 months total). The staff is allowing the extended interval for Type C LLRTs be increased to 75 months with the requirement that a licensee's post-outage report include the margin between the Type Band Type C leakage rate summation and its regulatory limit. In addition, a corrective action plan shall be developed to restore the margin to an acceptable level. The staff is also allowing the non-routine emergent extension out to 84-months as applied to Type C valves at a site, with some exceptions that are detailed in NEI 94-01, Revision 3. At no time shall an extension be allowed for Type C valves that are restricted categorically (e.g., BWR [main steam isolation valves (MSIVs)]), and those valves with a history of leakage, any valves held to either a less than maximum interval or to the base refueling cycle interval.

Only non-routine emergent conditions allow an extension to 84 months. The licensee's response to Condition 1 was addressed as three separate issues: Condition 1, Issue 1 The allowance of an extended interval for Type C LLRTs of 75 months carries the requirement that a licensee's post-outage report include the margin between the Type B and Type C leakage rate summation and its regulatory limit. LSCS Response to Condition 1, Issue 1 The post-outage report shall include the margin between the Type B and Type C Minimum Pathway Leak Rate (MNPLR) summation value, as adjusted to include the estimate of applicable Type C leakage understatement, and its regulatory limit of 0.60 La. Condition 1, Issue 2 A corrective action plan shall be developed to restore the margin to an acceptable level. LSCS Response to Condition 1, Issue 2 When the potential leakage understatement adjusted Types Band C MNPLR total is greater than the LSCS leakage summation limit of 0.5 La, but less than the regulatory limit of 0.6 La, then an analysis and determination of a corrective action plan shall be prepared to restore the leakage summation margin to less than the LSCS leakage limit. The corrective action plan should focus on those components which have contributed the most to the increase in the leakage summation value and what manner of timely corrective action, as deemed appropriate, best focuses on the prevention of future component leakage performance issues so as to maintain an acceptable level of margin. Condition 1, Issue 3 Use of the allowed 9-month extension for eligible Type C valves is only authorized for non-routine emergent conditions.

LSCS Response to Condition 1, Issue 3 LSCS will apply the 9-month grace period only to eligible Type C components and only for non-routine emergent conditions.

Such occurrences will be documented in the record of tests. Condition 2 The basis for acceptability of extending the ILRT interval out to once per 15 years was the enhanced and robust containment inspection program and the local leakage rate testing of penetrations.

Most of the containment leakage experienced has been attributed to penetration leakage and penetrations are thought to be the most likely location of most containment leakage at any time. The containment leakage condition monitoring regime involves a portion of the penetrations being tested each refueling outage, nearly all LLRTs being performed during plant outages. For the purposes of assessing and monitoring or trending overall containment leakage potential, the as-found minimum pathway leakage rates for the just tested penetrations are summed with the as-left minimum pathway leakage rates for penetrations tested during the previous 1 or 2 or even 3 refueling outages. Type C tests involve valves, which in the aggregate, will show increasing leakage potential due to normal wear and tear, some predictable and some not so predictable.

Routine and appropriate maintenance may extend this increasing leakage potential.

Allowing for longer intervals between LLRTs means that more leakage rate test results from farther back in time are summed with fewer just tested penetrations and that total is used to assess the current containment leakage potential.

This leads to the possibility that the LLRT totals calculated understate the actual leakage potential of the penetrations.

Given the required margin included with the performance criterion and the considerable extra margin most plants consistently show with their testing, any understatement of the LLRT total using a 5-year test frequency is thought to be conservatively accounted for. Extending the LLRT intervals beyond 5 years to a 75-month interval should be similarly conservative provided an estimate is made of the potential understatement and its acceptability determined as part of the trending specified in NEI TR 94-01, Revision 3, Section 12.1. When routinely scheduling any LLRT valve interval beyond 60-months and up to 75-months, the primary containment leakage rate testing program trending or monitoring must include an estimate of the amount of understatement in the Types B and C total leakage, and must be included in a licensee's post-outage report. The report must include the reasoning and determination of the acceptability of the extension, demonstrating that the LLRT totals calculated represent the actual leakage potential of the penetrations.

The licensee's response to Condition 2 was addressed as two separate issues: Condition 2, Issue 1 Extending the Type C, LLRT intervals beyond 5 years to a 75-month interval should be similarly conservative provided an estimate is made of the potential understatement and its acceptability determined as part of the trending specified in NEI TR 94-01, Revision 3, Section 12.1. LSCS Response to Condition 2, Issue 1 The change in going from a 60-month extended test interval for Type C tested components to a 75-month interval, as authorized under NEI 94-01, Revision 3-A, represents an increase of 25% in the LLRT periodicity.

As such, LSCS will conservatively apply a potential leakage understatement adjustment factor of 1.25 to the actual As-Left leak rate for each Type C component currently on greater than a 60-month test interval up to the 75-month extended test interval.

This will result in a combined conservative Type C total for all 75-month LLRTs being "carried forward" and will be included whenever the total leakage summation is required to be updated (either while on-line or following an outage). When the potential leakage understatement adjusted leak rate total for those Type C components being tested on greater than a 60-month test interval up to the 75-month extended test interval is summed with the non-adjusted total of those Type C components being tested at less than or equal to a 60-month test interval, and the total of the Type B tested components, results in the MNPLR being greater than the LSCS leakage summation limit of 0.50 La, but less than the regulatory limit of 0.6 La, then an analysis and corrective action plan shall be prepared to restore the leakage summation value to less than the LSCS leakage limit. The corrective action plan should focus on those components which have contributed the most to the increase in the leakage summation value and what manner of timely corrective action, as deemed appropriate, best focuses on the prevention of future component leakage performance issues. Condition 2, Issue 2 When routinely scheduling any LLRT valve interval beyond 60-months and up to 75-months, the primary containment leakage rate testing program trending or monitoring must include an estimate of the amount of understatement in the Type B and C total, and must be included in a licensee's post-outage report. The report must include the reasoning and determination of the acceptability of the extension, demonstrating that the LLRT totals calculated represent the actual leakage potential of the penetrations.

LSCS Response to Condition 2, Issue 2 If the potential leakage understatement adjusted leak rate MNPLR is less than the LSCS leakage summation limit of 0.50 La, then the acceptability of the greater than 60-month test interval up to the 75-month LLRT extension for all affected Type C components has been adequately demonstrated and the calculated local leak rate total represents the actual leakage potential of the penetrations.

In addition to Condition 1, Issues 1 and 2, which deal with the MNPLR Types B and C summation margin, NEI 94-01, Revision 3-A, also has a margin-related requirement as contained in Section 12.1, Report Requirements.

A post-outage report shall be prepared presenting results of the previous cycle's Type B and Type C tests, and Type A, Type B and Type C tests, if performed during that outage. The technical contents of the report are generally described in ANSI/ANS-56.8-2002 and shall be available on-site for NRC review. The report shall show that the applicable performance criteria are met, and serve as a record that continuing performance is acceptable.

The report shall also include the combined Type B and Type C leakage summation, and the margin between the Type B and Type C leakage rate summation and its regulatory limit. Adverse trends in the Type B and Type C leakage rate summation shall be identified in the report and a corrective action plan developed to restore the margin to an acceptable level. At LSCS, in the event an adverse trend in the aforementioned potential leakage understatement adjusted Types B and C summation is identified, then an analysis and determination of a corrective action plan shall be prepared to restore the trend and associated margin to an acceptable level. The corrective action plan shall focus on those components which have contributed the most to the adverse trend in the leakage summation value and what manner of timely corrective action, as deemed appropriate, best focuses on the prevention of future component leakage performance issues. At LSCS, an adverse trend is defined as three (3) consecutive increases in the final pre-mode change Types Band C MNPLR leakage summation values, as adjusted to include the estimate of applicable Type C leakage understatement, as expressed in terms of La. NRC Staff Assessment of Conditions 1 and 2 The LAR indicated that the post-outage report will include the margin between the Type Band Type C minimum pathway leak rate summation value adjusted for understatement and the acceptance criterion.

Should the Type Band C combined total exceed an administrative limit of 0.5 La but be less than the TS acceptance value, then an analysis will be performed and a corrective action plan prepared to restore and maintain the leakage summation margin to less than the LSCS leakage limit. The LAR also stated that LSCS will apply the 9 month grace period only to eligible Type C tested components and only for non-routine emergent conditions.

The licensee acknowledges these two conditions and the likelihood that longer test intervals would increase the understatement of actual leakage potential given the method by which the totals are calculated, and will assign additional margin for monitoring acceptability of results via administrative limits and understatement contribution adjustments.

Therefore, the licensee addressed and satisfied NRC Conditions 1 and 2 of NEI 94-01 Revision 3-A. 3.6 Containment and Plant Systems Evaluation of Specific Changes to TS 5.5.13 Based on its review of the licensee's LAR dated October 26, 2016, as supplemented by letters dated February 16, July 17, September 17, and October 3, 2017, and the regulatory and technical evaluations above, the NRC staff finds that the licensee has adequately addressed the applicable NRC conditions to demonstrate acceptability of adopting NEI 94-01, Revision 3-A, and the conditions and limitations specified in NEI 94-01, Revision 2-A, as the 10 CFR 50, Appendix J, Option B, implementation documents.

Therefore, the proposed change to TS 5.5.13.a to replace RG 1.163 with references to NEI 94-01, Revision 3-A, and the conditions and limitations specified in NEI 94-01, 2-A, is acceptable.

The exceptions in TS 5.5.13.a.1 and TS 5.5.13.a.2 regarding next Type A test for Unit 1 and Unit 2, respectively, are no longer necessary as that date has passed with the test having been completed.

Therefore, the proposed deletion of the exceptions from the TS is acceptable.

Therefore, the proposed changes to TS 5.5.13 for Unit 1 and Unit 2 are acceptable.

The NRC staff also reviewed the proposed deletion of Conditions 2.D.(e) and 2.D.(c) from LSCS Unit 1 and Unit 2 Renewed Facility Operating Licenses, respectively.

The reference to "paragraph 111.D of Appendix J" in these conditions is a carryover from "Option A -Prescriptive Requirements" in Appendix J. Similar requirements under "Option B -Performance-Based Requirements" in Appendix J are governed by the applicable NEI guidance documents and NRC Safety Evaluations.

The NRC staff concludes that the conditions are no longer needed since the licensee has adopted Option B. 3.7 Conclusion

-Containment and Plant Systems Assessment Based on the preceding regulatory and technical evaluations, the NRC staff finds that the licensee has adequately implemented its primary containment leakage rate testing program consisting of ILRT and LLRT. The results of the recent ILRTs and LLRTs demonstrate acceptable performance and that the structural and leak-tight integrity of the containment structure is adequately managed and will continue to be periodically monitored and managed by the ILRTs and LLRTs. The staff finds that the licensee has addressed the NRC conditions to demonstrate acceptability of adopting TR NEI 94-01, Revision 3-A, and the limitations and conditions identified in the staff SE incorporated in TR NEI 94-01, Revision 2-A, without undue risk to public health and safety. Therefore, the staff finds that the proposed changes to LSCS Unit 1 and Unit 2 TS 5.5.13 regarding the primary containment leakage rate testing program are acceptable.

3.8 Additional

Evaluation

-Structural Assessment The implementation document that is currently referenced in the LSCS TS 5.5.13, "Primary Containment Leakage Rate Testing Program," is RG 1.163, "Performance-Based Containment Leak-Test Program," September 1995. This regulatory guide endorsed TR NEI 94-01, Revision 0, "Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J," dated July 26, 1995, as a document that provides methods acceptable to the NRC staff for complying with the provisions of Option B of 10 CFR Part 50, Appendix J, subject to four regulatory positions delineated in Section C of the RG. NEI 94-01, Revision 0, includes provisions that allow the performance-based Type A test interval to be extended to up to 10 years, based upon two consecutive successful tests. Revision 2-A of TR NEI 94-01 describes an approach for implementing the optional performance-based requirements of Option B of 10 CFR 50, Appendix J. It incorporates the regulatory positions stated in RG 1.163 and includes provisions for extending Type A test intervals to up to 15 years. In its SE dated June 25, 2008, the NRC staff reviewed the acceptability of NEI 94-01, Revision 2. The staff concluded that the TR describes an acceptable approach for implementing the optional performance-based requirements of Option B of 1 O CFR 50, Appendix J, and is acceptable for referencing by licensees proposing to amend their TS in regards to containment leakage rate testing, subject to the specific limitations and conditions listed in Section 4.1 of the NRC staff's SE. As discussed in Section 3.4 of this SE, the NRC staff has found that the schedule of inspections provided for the third interval GISI program demonstrates LSCS compliance with the Limitation and Condition 2, including the NRC SE Section 3.1.1.3 in NEI 94-01, Revision 2-A. as well as ASME Ill,Section XI, Division 1, Subsection IWE/IWL. Guidance for extending Type C Local Leak Rate Test (LLRT) intervals beyond 60 months is given in TR NEI 94-01, Revision 3-A. This amendment also requests to extend the Type C local leak rate test interval up to 75 months. Based on its regulatory and technical evaluation of the licensee's submittal of October 26, 2016, as supplemented, the NRC staff concludes that the age-related degradation and structural integrity of the LSCS Units 1 and 2 primary containments are adequately managed and the results of the GISI demonstrate acceptable performance of the LSCS Units 1 and 2 primary containments.

The LSCS primary containment will continue to be periodically inspected, as required by 1 O CFR 50.55a and the ASME Boiler and Pressure Vessel Code, according to the GISI program if the current Type A test interval is extended from 10 years to 15 years. Therefore, the staff concludes that the LSCS GISI results and operating experience support the extension of Type A test interval.

3.9 Probabilistic

Risk Assessment

3.9.1 Background

and Regulatory Basis Section 9.2.3.1, "General Requirements for ILRT Interval Extensions beyond Ten Years," of NEI 94-01, Revision 3-A states that plant-specific confirmatory analyses are required when extending the Type A ILRT interval beyond 10 years. Section 9.2.3.4, "Plant-Specific Confirmatory Analyses," of NEI 94-01 states that the assessment should be performed using the approach and methodology described in the EPRI TR 1018243, "Risk Impact Assessment of Extended Integrated Leak Rate Testing Intervals." The analysis is to be performed by the licensee and retained in the plant documentation and records as part of the basis for extending the ILRT interval.

In its SE dated June 25, 2008, the NRG staff found the methodology in NEI 94-01, Revision 2, and EPRI TR-1009325, Revision 2, "Risk Impact Assessment of Extended Integrated Leak Rate Testing Intervals, Final Report," August 2007 (ADAMS Accession No. ML072970208), acceptable for referencing by licensees proposing to amend their TS to permanently extend the ILRT interval to 15 years, provided certain conditions are satisfied.

These conditions, set forth in Section 4.2 of the safety evaluation report (SER) for EPRI TR-1009325, Revision 2, stipulate that: 1. The licensee submit documentation indicating that the technical adequacy of their Probabilistic Risk Assessment (PRA) is consistent with the requirements of Regulatory Guide (RG) 1.200, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities," relevant to the ILRT extension application.

Additional application specific guidance on the technical adequacy of a PRA used to extend ILRT intervals is provided in the SER for EPRI TR 1009325, Revision 2. 2. The licensee submits documentation indicating that the estimated risk increase associated with permanently extending the ILRT surveillance interval to 15 years is small and consistent with the clarification provided in Section 3.2.4.6 of the SER for EPRI TR 1009325, Revision 2. 3. The methodology in EPRI TR-1009325, Revision 2, is acceptable provided the average leak rate for the pre-existing containment large leak accident case (i.e., accident case 3b) used by licensees is assigned a value of 100 times the maximum allowable leakage rate (La) instead of 35 La. 4. A license amendment request (LAR) is required in instances where containment over pressure is relied upon for emergency core cooling system (ECCS) performance.

3.9.2 Plant-Specific Risk Evaluation The licensee performed a risk impact assessment for extending the Type A containment ILRT interval to once in 15 years. The risk assessment was provided in Attachment 3 to the LAR submitted October 26, 2016. By letter dated August 8, 2017, the licensee provided additional information in response to the NRC staff's RAls. In Section 3.3.1 of Attachment 1 and Section 1.1 of Attachment 3 to the LAR, the licensee stated that the plant-specific risk assessment follows the guidance in NEI 94-01, Revision 3-A; the methodology described in EPRI TR-1018243 (also identified as EPRI TR-1009325, Revision 2-A); and the NRC regulatory guidance outlined in RG 1.174, Revision 2, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis," May 2011 (ADAMS Accession No. ML 100910006).

Additionally, the licensee used the methodology from Calvert Cliffs Nuclear Power Plant (ADAMS Accession No. ML020920100) to assess the risk from undetected containment leaks due to steel liner corrosion.

The licensee addressed each of the four conditions for the use of EPRI TR-1009325, Revision 2, which are listed in Section 4.2 of the NRC SER. A summary of how each condition has been met is provided in the sections below. 3.9.2.1 Technical Adequacy of the PRA The first condition stipulates that the licensee submits documentation indicating that the technical adequacy of their PRA is consistent with the requirements of RG 1.200 relevant to the ILRT extension application.

Consistent with the information provided in Regulatory Issue Summary (RIS) 2007-06, "Regulatory Guide 1.200 Implementation," dated March 22, 2007 (ADAMS Accession No. ML070650428), the NRC staff will use Revision 2 of RG 1.200, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities," March 2009 (ADAMS Accession No. ML090410014), to assess technical adequacy of the PRA used to support risk-informed applications received after March 2010. In Section 3.2.4.1 of the SER for NEI 94-01, Revision 2 and EPRI TR-1009325, Revision 2, the NRC staff states that Capability Category I of the ASME PRA standard shall be applied as the standard for assessing PRA quality for ILRT extension applications, since approximate values of core damage frequency (CDF) and large early release frequency (LERF) and their distribution among release categories are sufficient to support the evaluation of changes to ILRT frequencies.

As discussed in Appendix A to Attachment 3 of the LAR, the LSCS risk assessment performed to support the ILRT application uses the current Unit 2 Level 1 and Level 2 internal events PRA (IEPRA) model of record, which was completed in November 2015 and includes consideration of internal flooding.

In its August 8, 2017, response to PRA RAI 07, the licensee explained that there are no significant differences relevant to IEPRA modelling between Units 1 and 2 except for some differences in power supplies for shared equipment.

The licensee explained that the Unit 1 CDF is 0.35 percent less and the Unit 1 LERF is 0.5 percent less than for Unit 2. Accordingly, the Unit 2 results provided in the LAR bound the Unit 1 results. In Section A.2 of Appendix A to Attachment 3 to the LAR, the licensee describes the process used for controlling the model and for ensuring that the model reflects the as-built and as-operated plant. The licensee has a process for continued PRA maintenance and update, including procedures for regularly scheduled and interim PRA model updates and for tracking issues identified as potentially affecting the PRA model. The licensee performed a review of the plant modifications and changes and concluded that there are no plant changes that have not yet been incorporated in the PRA model that would affect this application.

The licensee stated that the LSCS IEPRA underwent a peer review in 2008 against the ASME PRA standard RA-Sa-2002 and the clarifications of RG 1.200, Revision 1. Additionally, in 2014, the licensee performed a self-assessment against the ASME/ANS PRA standard RA-Sa-2009, as clarified by Revision 2 of RG 1.200. In its August 8, 2017, response to PRA RAI 02, the licensee stated that all changes made to the IEPRA since the last peer review were justified as PRA maintenance.

The NRC staff notes that in the supplement dated July 20, 2017 (ADAMS Accession No. ML 172010396), related to the application for "Fourth 10-Year Interval lnservice Inspection Program Relief Requests," the licensee provided a summary of all changes made to the IEPRA model after the 2008 peer review, along with an explanation of why each change does not constitute a PRA upgrade that would require a focused-scope peer review. The NRC staff notes that one of the changes made to the model subsequent to the full-scope peer-review was the use of the EPRI Human Reliability Analysis (HRA) Calculator to quantify the human error probabilities (HEPs). The use of the HRA Calculator can potentially qualify as a PRA model upgrade that would require a focused-scope peer review per RG 1.200, Revision 2. The licensee stated however, that the change to use of the HRA calculator constitutes a PRA update because the HRA methods used for calculating the HEPs were not changed from the full-scope peer review. The licensee did not confirm that the significant accident sequences or accident progression sequences were not impacted by this change. The licensee further stated that a review of the HRA was performed by an experienced HRA analyst to confirm that none of the changes made to the HRA after the peer review would qualify as PRA upgrade. This does not constitute as a NRC endorsed review process for PRA upgrade. However, the NRC staff notes that: 1. the licensee asserted that the HRA methods remain unchanged

2. the licensee performed a review of the HRA and 3. sufficient margin exists between the reported risk metrics for the application and the acceptance guidelines, as discussed in Section 3.2.3 of this SE, The NRC staff finds that these aspects provide additional confidence that any uncertainties in the implementation of the EPRI HRA Calculator and lack of focused scope peer review will not change the conclusions of this SE. Therefore, the NRC staff concludes that the licensee's assessment is acceptable for this application.

It should be noted that the acceptability in the context of this application does not eliminate the possibility of staff scrutiny and review of the use of the EPRI HRA Calculator for other risk-informed LARs from the licensee where acceptability requirements can be different.

The licensee stated that the 2008 peer review resulted in 13 findings; 11 findings were associated with SRs not met and two findings were associated with SRs meeting Capability Category I. These findings were provided in the LAR and supplemented in the licensee's August 8, 2017, response to PRA RAI 01. The NRC staff reviewed these findings and observations (F&Os) and the associated dispositions and determined that they have minimal impact on the ILRT application.

Table A-2 of Appendix A to Attachment 3 of the LAR presents three gap findings for SRs not met, and the response to PRA RAI 01 presents four additional gap findings for SRs met at Capability Category I. In response to PRA RAI 03, the licensee provided justification for determination that the three gap findings associated with SRs not met have minimal impact on the ILRT application, as discussed below. Gap #1 identified issues with the screening of flood locations stating that the screening process used individual Conditional Core Damage Probabilities (CCDPs), instead of the "bounding" CCDP, which is defined in the PRA standard (SR IFQU-A3) as "the highest of the CCDP values for the flood scenarios in an area." Therefore it appears that the internal flooding PRA may have screened out more flood sources than recommended by the PRA standard.

In response to PRA RAI 03 the licensee stated that it reviewed the screening analysis and concluded that the screening of flood locations meets the intent of SR IFQU-A3 regarding use of a bounding CCDP in screening flood locations.

Because the licensee confirmed that the intent of the applicable SR is met, the staff concludes that this gap has no impact on the application.

Gap #2 identified that surveillance test data were not used in data development for the internal events PRA. The resolution states that "it is expected that the assumptions used to collect data from Maintenance Rule and [Mitigating Systems Performance Index] MSPI data sources, yield acceptable data" and review of surveillance test data "will likely result in very few changes and likely negligible changes to failure probabilities." In response to PRA RAI 03 the licensee explained how the surveillance test data not used in the data development for IEPRA components will have little impact on the failure rates of risk significant basic events given the level of reliance of those events on surveillance data and on review of surveillance procedures for any needed refinements to the demand count. The staff concludes that this gap is acceptable for the application because the licensee assessed the impact of not including the surveillance test data in the component failure rates and concluded it has little impact on the risk significant failure rates. Gap #3 identified that Environmental Qualification is credited for operability of instrumentation affected by spray effects. In its August 8, 2017, response to PRA RAI 03, the licensee explained that no credit was taken for operability of instrumentation affected by sprays other than equipment located in the drywell which is designed to withstand the impacts of a loss-of-coolant accident (LOCA). Because the licensee explained that the equipment credited for operability after a spray event is limited to the equipment inside the drywell, which is expected to withstand spray effects because it has been designed to withstand a LOCA, the staff concludes that this gap is acceptable for the application.

In Section 3.2.4.2 of the SER for NEI 94-01, Revision 2 and EPRI TR-1009325, Revision 2, the NRC staff states that: Although the emphasis of the quantitative evaluation is on the risk impact from internal events, the guidance in EPRI Report No. 1009325, Revision 2, Section 4.2.7, "External Events," states that: 'Where possible, the analysis should include a quantitative assessment of the contribution of external events (e.g., fire and seismic) in the risk impact assessment for extended ILRT intervals." This section also states that: "If the external event analysis is not of sufficient quality or detail to directly apply the methodology provided in this document [(i.e., EPRI Report No. 1009325, Revision 2)], the quality or detail will be increased or a suitable estimate of the risk impact from the external events should be performed." This assessment can be taken from existing, previously submitted and approved analyses or other alternate method of assessing an order of magnitude estimate for contribution of the external event to the impact of the changed interval.

Therefore, the NRC staff's review of the contribution of external events for this application is framed by the context that an order of magnitude estimate for the corresponding risk contribution is sufficient.

The licensee performed an analysis of the impact of external events in Section 5.7 of Attachment 3 of the LAR. For the evaluation of the acceptance criteria discussed in Section 3.9.2.2 of this SE, the licensee's analysis reflected the contribution from internal fire and seismic events quantitatively by scaling the internal events CDF by a multiplication factor based on the CDF of each initiator group. For other external events, the licensee determined their contribution to be negligible for this application as further discussed below. To assess the fire risk, the licensee used the current Unit 2 fire PRA (FPRA) model of record. In its August 8, 2017, response to PRA RAI 07, the licensee explained the general arrangement of Units 1 and 2 are the same including the arrangement of equipment and cable routing. The licensee explained that based on a previous set of interim FPRAs that the CDF for Unit 1 was approximately 6 percent less than the CDF for Unit 2. Accordingly, the Unit 2 results that were used in the ILRT risk calculations were considered adequate to represent the fire risk associated with Unit 1. The licensee stated in the LAR, and clarified in response to PRA RAI 04, that the LSCS FPRA underwent a peer review in December 2015, which followed the NEI 07-12 process (ADAMS Accession No. ML 102230070) and was performed against ASME/ANS PRA standard RA-Sa-2009 along with the NRC clarifications/qualifications provided in RG 1.200, Revision 2. In the LAR, the licensee provided dispositions to all F&Os associated with SRs determined by the peer review to be not met. The NRC staff reviewed each F&O and its associated disposition.

The NRC staff observed that a number of non-conservatisms documented by the F&Os appeared to have not been resolved and requested additional information.

In its August 8, 2017, response to PRA RAI 05, the licensee provided assessments of the significance of these F&Os identified by the staff in the RAI. The NRC staff reviewed the licensee's assessments and finds that in a number of cases the licensee resolved the F&O as the result of evaluation performed since the peer review. In other cases, the licensee was able to show quantitatively using a sensitivity study or by other quantitative means that the potential risk impact of the F&O was small. In some cases, the licensee provided qualitative rationale for why the impact was minimal. Additionally, in response to PRA RAI 05, the licensee stated that the fire GDF and LERF are estimated to be bounding and overall conservative in spite of non-conservatism that exists as a result of some unresolved FPRA F&Os. The FPRA modeling conservatism cited by the licensee includes no credit for installation of a Hardened Containment Vent Systems or manual containment vent actions for the existing vent systems which would reduce the CDFs for both units; conservative hot gas layer modeling in the divisional essential switchgear rooms and the Main Auxiliary Electric Equipment Rooms; conservative cooling dependency assumptions for Containment Spray Cooling Systems rooms; no credit for a portable backup system for the Instrument Air system. In addition to these modelling conservatisms, NRG staff notes other FPRA modeling conservatisms identified in Section 5.7.2 of Attachment 3 of the LAR such as conservative fire damage modeling conservatively assumed cable routing. In PRA RAI 05, the NRG also requested clarifications of whether any "unapproved/unreviewed analysis methods" were used in the FPRA. In response to the RAI PRA 05, the licensee cited the following statement from the 2015 FPRA peer review: The LaSalle Peer review included all the SRs and all applicable reference SRs .... There were no "unreviewed Analysis Methods" identified during the review. Based on the above and because sufficient margin exists to the acceptance criteria, as discussed in Section 3.9.2.2 of this SE, the NRG staff concludes that the licensee's order of magnitude estimate for the contribution of internal fire risk is acceptable for the ILRT application.

The external events risk assessment documented in the LAR provides a bounding seismic GDF value based on the NRG staff's Generic Issue (GI) 199 study "Implications of Updated Probabilistic Seismic Hazard Estimates in Central and Eastern United States on Existing Plants: Safety/Risk Assessment," August 201 O (ADAMS Accession No. ML 100270756), which contains the postulated GDF using the updated 2008 U.S. Geological Survey seismic hazard curves. The licensee used the maximum value of the seismic GDF calculated for LSCS as part of the Gl-199 issue of 3.7E-06/year.

The staff noted that based on the October 27, 2015, seismic hazard re-evaluation performed in response to Recommendation 2.1 of the Near-Term Task Force (ADAMS Accession No. ML 15194A015), the staff concluded that a seismic risk re-evaluation is not merited. Therefore, the Gl-199 analysis represents the most recent available estimate of the seismic risk for LSCS. Therefore the NRG staff finds that the licensee's use of this seismic GDF to provide an order of magnitude estimate of the seismic risk contribution is acceptable for this application.

As stated in Section 5.7.2 of Attachment 3 of the LAR, the licensee evaluated other external events, including external floods, transportation, and nearby facility accidents, based on the LSCS Individual Plant Examination for External Events (IPEEE) analysis performed in 1994. The licensee concluded that these events are considered negligible in estimation of the external events impact on the ILRT extension risk assessment.

In its August 8, 2017, response to PRA RAI 06, the licensee assessed the applicability of these conclusions to the current as-built and as-operated plant, and any changes in the plant or its environs since the IPEEE analysis was performed.

Regarding the high wind hazard, the licensee stated that there are no changes to major structures or the location of equipment important to safe shutdown since the IPEEE. The licensee stated that the external flooding hazard re-evaluation performed in response to the Near-Term Task Force recommendation (ADAMS Accession No. ML 12053A340) found two flood causing mechanisms that are not bounded by the design basis hazard flood level. The licensee stated that the plant is effectively protected from these two flood mechanisms with adequate margin. The licensee also stated and the station relies on permanent passive flooding protection features and requires no human actions to protect key structures, systems, and components.

The licensee identified for the transportation and nearby facility accident hazard a toxic chemical hazards analysis performed since the IPEEE, regular surveys for use of chlorine, and detection that is installed to inform operators of an ammonia hazard, but identified no issues that indicate an increase in the risk of these hazards. Based on the licensee's assessment, the NRC staff concludes that the risk associated with other external events remains negligible for the ILRT application.

Based on the above considerations, the NRC staff finds the licensee's analysis of the impact of external events acceptable for the ILRT application.

Furthermore, the licensee has evaluated its internal events PRA against the current PRA standard and Revision 2 of RG 1.200. The NRC staff finds that the licensee has addressed the findings and gaps from the peer reviews and that they have no impact on the results of this application.

Therefore, the NRC staff concludes that the internal events PRA model used by the licensee is of sufficient technical adequacy to support the evaluation of changes to ILRT frequencies.

Accordingly, the first condition is met. 3.9.2.2 Estimated Risk Increase The second condition stipulates that the licensee submits documentation indicating that the estimated risk increase associated with permanently extending the ILRT interval to 15 years is small, and consistent with the guidance in RG 1.174 and the clarification provided in Section 3.2.4.5 of the NRC SER for NEI 94-01, Revision 2, and EPRI TR-1009325, Revision 2. Specifically, a small increase in population dose should be defined as an increase in population dose of less than or equal to either 1.0 person-rem per year or 1 percent of the total population dose, whichever is less restrictive.

In addition, a small increase in conditional containment failure probability (CCFP) should be defined as a value marginally greater than that accepted in previous one-time 15-year ILRT extension requests.

This would require that the increase in CCFP be less than or equal to 1.5 percentage points. Additionally, for plants that rely on containment over-pressure for net positive suction head (NPSH) for ECCS injection, both CDF and LEAF will be considered in the ILRT evaluation and compared with the risk acceptance guidelines in RG 1.174. As discussed in Section 3.9.2.4 of this Safety Evaluation, LSCS Units 1 and 2 do not rely on containment over-pressure for ECCS performance.

Thus, the associated risk metrics include LEAF, population dose, and CCFP. The licensee reported the results of the plant-specific risk assessment in Section 3.3.3 of Attachment 1 to the LAR. Details of the risk assessment are provided in Attachment 3 to the LAR. The reported risk impacts are based on a change in the Type A containment ILRT frequency from three tests in 1 O years (the test frequency under 1 O CFR 50, Appendix J, Option A) to one test in 15 years and also account for the risk from undetected containment leaks due to steel liner corrosion.

The following conclusions can be drawn from the licensee's analysis associated with extending the Type A ILRT frequency:

1. The reported increase in LEAF for internal events is 2.16E-08/year for both units. The increase in LEAF for combined internal and external events is 4.15E-07/year for both units. The risk contribution from external events includes the effects of internal fires and seismic events, as discussed in Section 3.9.2.1 of this Safety Evaluation.

These changes in risk are considered to be "small" (i.e., between 1 E-06/year and 1 E-07/year) per the acceptance guidelines in RG 1.17 4. An assessment of total baseline LEAF is required to show that the total LERF is less than 1 E-05/year.

The licensee estimated the total LERF for internal and external events as 6.60E-06/year for both units. The total LERF, which includes the increase in ILRT interval, is below the acceptance guideline of 1 E-05/year in RG 1.17 4 for a "small" change. 2. The reported change in Type A ILRT frequency from three in 10 years to once in 15 years results in a reported increase in the total population dose for both units of 1.23E-2 person-rem/year from internal events. As indicated in Table 5.7-4 of Attachment 3 of the LAR, this estimate increases to 2.36E-01 person-rem/year when both internal and external events are considered.

The reported increase in total population dose is below the values provided in EPRI TR-1009325, Revision 2 A, and defined in Section 3.2.4.6 of the NRG SER for NEI 94-01, Revision 2. Thus, the increase in the total integrated plant risk for the proposed change is considered small and supportive of the proposed change. 3. The increase in CCFP due to change in test frequency from three in 1 O years to once in 15 years for both units is 0.99 percent from internal events. As indicated in Table 5.7-4 of Attachment 3 of the LAR, this estimate remains at 0.99 percent when both internal and external events are considered.

This value is below the acceptance guidelines in Section 3.2.4.6 of the NRG SER for NEI 94-01, Revision 2. In Appendix B to Attachment 3 of the LAR, the licensee also provided a separate assessment of the risk impacts associated with extending the surveillance frequency to 15 years for the Drywell to Wetwell Bypass Leak Rate Test (DWBT). The licensee stated that these tests are controlled under the Surveillance Frequency Control Program (SFCP). However potential undetected drywell to suppression chamber leakage impacts the risk metrics for the ILRT interval extension requested in the current submittal.

In PRA RAI 08 (ADAMS Accession No. ML 17151 A382), the NRG staff noted that the LAR does not ask for an extension of the DWBT interval and requested explanation for the purpose of DWBT risk analysis including determination of the risk impact of the DWBT interval on the ILRT interval extension.

In its August 8, 2017, response to PRA RAI 08, the licensee explained that prior to the SFCP, plants with containments similar to LSCS were expected to submit a DWBT LAR or submit the DWBT and ILRT interval extension requests together.

However, given the transition of DWBT interval extension to the SFCP, these submittals are no longer necessary.

The licensee in hindsight stated that inclusion of the risk of DWBT interval extension in the ILRT LAR was unnecessary and that an NRG review of Appendix B is not being requested.

Therefore the staff did not review the risk assessment provided in Appendix B to Attachment 3 to the LAR. It should be noted that the licensee has also provided risk assessment results based on expert elicitation of the probability for large and small pre-existing leaks in the containment in Section 6.2 of Attachment 3 of the LAR. As stated in Section 3.2.4.5 of the SER for NEI 94-01, Revision 2 and EPRI TR-1009325, Revision 2, the staff does not accept the expert elicitation as presented in the appendices of EPRI Report No. 1009325, Revision 2. Therefore, the risk assessment based on expert elicitation has not been considered in the staff's evaluation of this application.

Based on the risk assessment results, the NRG staff concludes that the increase in LERF is small and consistent with the acceptance guidelines of RG 1.17 4, and the increase in the total population dose and the magnitude of the change in the CCFP for the proposed change are small and supportive of the LAR. The defense-in-depth philosophy is maintained as the independence of barriers will not be degraded as a result of the requested change, and the use of the three quantitative risk metrics collectively ensures that the balance between prevention of core damage, prevention of containment failure, and consequence mitigation is preserved.

Accordingly, the second condition is met. 3.9.2.3 Leak Rate for the Large Pre-Existing Containment Leak Rate Case The third condition stipulates that in order to make the methodology in EPRI TR-1009325, Revision 2 acceptable, the average leak rate for the pre-existing containment large leak rate accident case (i.e., accident case 3b) used by the licensees shall be 100 La instead of 35 La. As noted by the licensee in Table 3.3.1-1 in Section 3.3.1 of Attachment 1 to the LAR, the methodology in EPRI TR-1009325, Revision 2-A, incorporated the use of 100 La as the average leak rate for the pre-existing containment large leakage rate accident case (accident case 3b), and this value has been used in the LSCS plant-specific risk assessment.

Accordingly, the third condition is met. 3.9.2.4 Applicability if Containment Overpressure is Credited for ECCS Performance The fourth condition stipulates that in instances where containment over-pressure is relied upon for ECCS performance, a LAR is required to be submitted.

In Section 5.8 of Attachment 3 of the LAR, the licensee stated that containment overpressure is not relied upon for ECCS performance at LSCS. Accordingly, the fourth condition is not applicable.

3.9.3 Conclusion

-Risk Assessment Based on the above, the NRC staff concludes that the proposed LAR for a permanent extension of the Type A containment ILRT frequency to once in 15 years for LSCS Units 1 and 2 is acceptable.

3.10 Overall Conclusion

-Technical Evaluation Based on the above discussions the NRC staff finds the licensee's proposed changes acceptable for the reasons stated.

4.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Illinois State official was notified of the proposed issuance of the amendment on September 8, 2017. The State official had no comments.

5.0 ENVIRONMENTAL

CONSIDERATION The amendments change requirements with respect to installation or use of a facility's components located within the restricted area as defined in 1 O CFR Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.

The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (82 FR 10597; February 14, 2017). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 1 O CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.

6.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) there is reasonable assurance that such activities will be conducted in compliance with the Commission's regulations, and {3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public. Principal Contributors:

N. Karipineni, NRR/SBPB M. Biro, NRR/APLA R. Pettis, NRR/ESEB Date of Issuance:

November 1 6 , 2 O 1 7 B. Hanson

SUBJECT:

LASALLE COUNTY STATION, UNITS 1 AND 2-ISSUANCE OF AMENDMENTS RE: REVISION OF TECHNICAL SPECIFICATIONS 5.5.13, "PRIMARY CONTAINMENT LEAKAGE RATE TESTING PROGRAM," FOR PERMANENT EXTENSION OF TYPE A AND TYPE C LEAK RATE TEST FREQUENCIES (CAC NOS. MF8700 AND MF8701; EPID L-2016-LLA-0021)

DATED NOVEMBER 16, 2017 DISTRIBUTION:

PUBLIC PM File Copy RidsACRS_MailCTR Resource RidsNrrDeEseb Resource RidsNrrDorlLpl3 Resource RidsNrrDraApla Resource RidsNrrDssSbpb Resource RidsNrrDssStsb Resource RidsNrrLAJBurkhardt Resource RidsNrrLASRohrer Resource RidsNrrPMLaSalle Resource RidsRgn3MailCenter Resource RPettis, NRR/DE/ESEB CTilton, NRR/DSS/STSB MBiro, NRR/DRA/APLA NKaripineni, NRR/DSS/SBPB ADAMS A ccess1on N ML 17283A085 o.: OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NAME BVaidya SRohrer (JBurkhardt for) DATE 10/17/17 10/16/17 OFFICE NRR/DRA/APLA/BC OGC-NLO NAME SRosenberg CKanatas -Revised DATE 09/07/17 10/23/17 -11/16/17 (*) N b t f I h t SEI t o su s an ,a c ange o npu NRR/DSS/STSB/BC (A) NRR/DE/ESEB/BC JWhitman BWittick (*) 10/17/17 09/18/17 NRR/DORULPL3/BC NRR/DORL/LPL3/PM DWrona BVaidya 11/16/17 11/16/17 OFFICIAL RECORD COPY memo NRR/DSS/SBPB/BC RDennig (*) 10/06/17

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