ML21060B435

NRR E-mail Capture - Second Round - Request for Additional Information (Rais) EPID-L-2020-LLA-0018, LaSalle License Amendment Request to Adopt Risk Informed Completion Times TSTF-505, Revision 2

ML21060B435
Person / Time
Site:	LaSalle
Issue date:	03/01/2021
From:	Bhalchandra Vaidya NRC/NRR/DORL/LPL3
To:	Kusumawatimurray P, Taken J Exelon Generation Co
References
L-2020-LLA-0018
Download: ML21060B435 (4)

Text

From: Vaidya, Bhalchandra Sent: Monday, March 1, 2021 8:08 AM To: Taken, Jason C.:(Exelon Nuclear); Kusumawatimurray, Putri:(GenCo-Nuc)

Subject:

SECOND ROUND - Request for Additional Information (RAIs) EPID-L-2020-LLA-0018, LaSalle License Amendment Request to Adopt Risk Informed Completion Times TSTF-505, Revision 2 Dwi and Jason,

Subject:

Second Round Request for Additional Information (RAIs) for LaSalle License Amendment Request to Adopt Risk Informed Completion Times TSTF-505, Revision 2, "Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b" By letter dated January 31, 2019 (ADAMS Accession No. ML20035E577), Exelon Generation Company, LLC (EGC) requested a revision to permit the use of Risk Informed Completion Times in accordance with TSTF-505, Revision 2, "Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b."

The proposed amendment would modify Technical Specifications (TS) requirements to permit the use of Risk Informed Completion Times in accordance with TSTF-505, Revision 2, "Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b," (ADAMS Accession No. ML18183A493).

By letter dated October 2, 2020, you responded to the first round of RAIs from EEEB. The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing your responses and has identified areas where additional information is needed to complete its review. Please find the second round draft request for additional information (RAI) below.

Subsequent to the clarification telephone conference on February 25, 2021, by email dated February 27, 2021, you have committed to provide the responses to these RAIs no later than 30 days from the date of this transmittal.

Please contact me, if you have any questions.

Thanks.

Bhalchandra K. Vaidya Licensing Project Manager, LaSalle Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission

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SECOND ROUND REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST TO ADOPT TSTF-505, REVISION 2 RISK-INFORMED COMPLETION TIMES

EXELON GENERATION COMPANY, LLC LASALLE COUNTY STATION UNITS 1 AND 2 DOCKET NOS. 50-373 AND 50-374 By a letter dated January 31, 2020, (Agencywide Documents Access and Management System (ADAMS)

Accession No. ML20035E577) Exelon Generation Company LLC (Exelon, the licensee) submitted a license amendment request (LAR) to modify the LaSalle County Station (LaSalle) Technical Specification (TS) requirements to permit the use of Risk Informed Completion Times (RICT) in accordance with Technical Specifications Task Force (TSTF) Traveler TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b, dated July 2, 2018 (ADAMS Accession No. ML18183A493). The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the request and supplemental information provided in letter dated October 1, 2020, LaSalle County Station Unit 1 And 2 - Response to Request for Additional Information for LaSalle License Amendment Request to Adopt Risk-Informed Completion Times TSTF-505, Revision 2 (ADAMS ML20275A270). The NRC staff has determined that additional information is necessary to complete its review.

APPLICABLE REGULATION General Design Criterion (GDC) 17, Electric power systems, states in part, An onsite electric power system and an offsite electric power system shall be provided to permit functioning of structures, systems, and components (SSCs) important to safety.

REQUEST FOR ADDITIONAL INFORMATION The LAR states:

The methodology for using the RICT Program is described in NEI 06-09-A, "Risk-Informed Technical Specifications Initiative 4b, Risk-Managed Technical Specifications (RMTS) Guidelines,"

Revision 0, which was approved by the NRC on May 17, 2007. Adherence to NEI 06-09-A is required by the RICT Program.

The proposed amendment is consistent with TSTF-505, Revision 2, "Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b."

The NRC staff is evaluating the LAR for consistency with the defense-in-depth philosophy as discussed in NEI 06-09-A and Regulatory Guide 1.174, Revision 2. Specifically, the NRC staff is evaluating conformance with the following criteria with respect to the non-accident unit in the scenario described in the NRC staffs RAI dated September 3, 2020, (ADAMS Accession No. ML20240A019) for the LaSalle Station:

• A reasonable balance is preserved among prevention of core damage, prevention of containment failure, and consequence mitigation.

• Over-reliance on programmatic activities as compensatory measures associated with the change in the licensing basis is avoided.

• System redundancy, independence, and diversity are preserved commensurate with the expected frequency, consequences of challenges to the system, and uncertainties (e.g., no risk outliers).

• The intent of the plants design criteria is maintained.

Table E1-1 of Enclosure 1 of the LAR, In Scope TS/LCO Conditions to Corresponding PRA Functions, provides PRA Success Criteria and Design Success Criteria for LCO conditions proposed for RICT consideration. The information provided in Table E1-1, considers the impact of proposed changes for a Design Basis Accident (DBA) in Unit 2 concurrent with a loss of offsite power on Unit 1. The NRC staff is evaluating the defense-in-depth capabilities available during those event(s) in development of Table E1-1s success criteria in accordance with the LaSalle Units current licensing basis. The LAR proposes changes to the TS Section 3.8, Electric Power System, requirements related to Completion Times (CTs) for Required Actions (RAs) to provide the option to calculate a longer RICT.

RAI-R2 EEEB 1: By letter dated October 1, 2020, Exelons response to EEOB TSTF-505 RAI No. 1, Technical Specifications Associated with TS 3.8 Electrical Power Systems impact on Non-accident Unit," indicates the use of site procedure LOA-AP-101, "Unit 1, AC Power System Abnormal". For the same scenario specified in the September 3, 2020, staff RAI, please provide the following:

• Details of any additional defense-in-depth capabilities at LaSalle, in line with stated criteria above, that would allow for a controlled, safe shutdown of the non-accident unit. This pertains to the requested changes to TS 3.8.1.B, TS 3.8.1.C and TS 3.8.1.E for the Division 2 DGs.

• Please also identify any capabilities assumed initially unavailable but eventually recovered including their recovery times and relevant impact.

• Clarification on when procedure LOA-AP-101 would be implemented (i.e. (1) prior to entry into the TS LCO or (2) during a postulated design basis accident condition).

RAI-R2 EEEB 2: For the conditions postulated in Table E1-1, please clarify if procedure LOA-AP-101, "Unit 1, AC Power System Abnormal," would be implemented for the safe shutdown of the non-accident unit under the same conditions specified in RAI EEEB 1 above, including the requested information for defense-in-depth capabilities, when the indicated Division 2 SSC is in a RICT for the following TSs:

• TS 3.3.8.1.A - One or more loss of power (LOP) instrument channels

• TS 3.8.4.A - 125 VDC battery charger

• TS 3.8.4.B & E - 125 VDC electrical power subsystem

• TS 3.8.7.A - AC Electrical power distribution subsystem

• TS 3.8.7.B - DC electrical power distribution subsystem

• TS 3.8.7.D - Opposite unit Division 2 AC or DC electrical power distribution subsystem RAI-R2 EEEB 3: The LAR also proposes changes to RHR systems or subsystems in TS sections 3.6 and 3.7. For the conditions postulated in Table E1-1, please clarify if procedure LOA-AP-101, "Unit 1, AC Power System Abnormal," would be implemented for the same scenario requiring safe shutdown of the non-accident unit when the TS-indicated Division 2 SSC is in a RICT.

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Bhalchandra K. Vaidya US Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Division of Operatig Reactor Licensing LPL3 301-415-3308 Bhalchandra.vaidya@nrc.gov

Hearing Identifier: NRR_DRMA Email Number: 1047 Mail Envelope Properties (SJ0PR09MB7216D645B92D9CC1BD267CAE8D9A9)

Subject:

SECOND ROUND - Request for Additional Information (RAIs)

EPID-L-2020-LLA-0018, LaSalle License Amendment Request to Adopt Risk Informed Completion Times TSTF-505, Revision 2 Sent Date: 3/1/2021 8:07:40 AM Received Date: 3/1/2021 8:07:40 AM From: Vaidya, Bhalchandra Created By: Bhalchandra.Vaidya@nrc.gov Recipients:

"Taken, Jason C.:(Exelon Nuclear)" <Jason.Taken@exeloncorp.com>

Tracking Status: None "Kusumawatimurray, Putri:(GenCo-Nuc)" <Putri.Kusumawatimurray@exeloncorp.com>

Tracking Status: None Post Office: SJ0PR09MB7216.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 8252 3/1/2021 8:07:40 AM Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date: