RS-21-055, Response to Third Round Request for Additional Information (Rals) for LaSalle License Amendment Request to Adopt Risk Informed Completion Times TSTF- 505, Revision 2, Provide Risk-Informed Extended.

Response to Third Round Request for Additional Information (Rals) for LaSalle License Amendment Request to Adopt Risk Informed Completion Times TSTF- 505, Revision 2, Provide Risk-Informed Extended.

ML21130A655
Person / Time
Site:	LaSalle
Issue date:	05/10/2021
From:	Demetrius Murray Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
EPID L-2020-LLA-0018, RS-21-055
Download: ML21130A655 (6)

Text

Exelon Generation ~

4300 Winfield Road Warrenville, IL 60555 www.exeloncorp.com 10 CFR 50.90 RS-21-055 May 10, 2021 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 LaSalle County Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-11 and NPF-18 NRG Docket Nos. 50-373 and 50-374

Subject:

Response to Third Round Request for Additional Information (RAls) for LaSalle License Amendment Request to Adopt Risk Informed Completion Times TSTF-505, Revision 2, "Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b"

References:

1. Letter from D. Murray (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "Application to Revise Technical Specifications to Adopt Risk Informed Completion Times TSTF-505, Revision 2, 'Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b,"' dated January 31, 2020 (ML20035E577)

2. Letter from B. Vaidya (Project Manager, U.S. Nuclear Regulatory Commission) to B. Hanson (Exelon Generation Company, LLC), "LaSalle County Station Unit 1 and 2 - Request for Additional Information for LaSalle License Amendment Request to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, 'Provide Risk-Informed extended Completion Times -

RITSTF Initiative 4b' (EPID L-2020-LLA-0018)," dated September 3, 2020

3. Letter from B. Vaidya (Project Manager, U.S. Nuclear Regulatory Commission) to B. Hanson (Exelon Generation Company, LLC), "LaSalle County Station Unit 1 and 2 - Correction to Request for Additional Information Regarding License Amendment Request to Adopt TSTF-505, Revision 2, 'Provide Risk-Informed extended Completion Times - RITSTF Initiative 4b' (EPID L-2020-LLA-0018)," dated September 16, 2020 (ML20253A227)

4. Letter from D. Murray (Exelon Generation Company, LLC), "LaSalle County Station, Unit Nos. 1 and 2 - Response to Request for Additional Information Regarding License Amendment Requests for Amendments to Renewed Facility Operating Licenses to Adopt 10 CFR 50.69, 'Risk-Informed Categorization and Treatment of Structures, Systems, and Components for Nuclear Power Reactors,' and to Adopt TSTF-505, Revision 2, 'Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b,' (EPID L-2020-

U.S . Nuclear Regulatory Commission May 10, 2021 Page 2 LLA-0017 AND EPID-L-2020-LLA-0018)," dated October 29, 2020 (ML20303A307)

5. Letter from B. Vaidya (Project Manager, U.S. Nuclear Regulatory Commission) to D. Rhoades (Exelon Generation Company, LLC), "Second Round Request for Additional Information (RAls) for LaSalle License Amendment Request to Adopt Risk Informed Completion Times TSTF-505, Revision 2, 'Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b,"' dated March 1, 2021 (ML21060B435)

6. Letter from D. Murray (Exelon Generation Company, LLC), "Response to Second Round Request for Additional Information (RAls) for LaSalle License Amendment Request to Adopt Risk Informed Completion Times TSTF-505, Revision 2, 'Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b,"' dated March 31, 2021 (ML21090A283)

7. Letter from B. Vaidya (Project Manager, U.S. Nuclear Regulatory Commission) to J. Taken (Exelon Generation Company, LLC), "REQUEST FOR ADDITIONAL INFORMATION (RAI) - LaSalle, EPID-L-2020-LLA-0018, License Amendment Request (LAR) re: TSTF-505," dated April 29, 2021 In Reference 1, Exelon Generation Company, LLC (EGC) submitted a request to the U.S.

Nuclear Regulatory Commission (NRC) for a revision to the Technical Specifications (TS)

(Appendix A) of Renewed Facility Operating License Nos. NPF-11 and NPF-18 for LaSalle County Station, Units 1 and 2.

Exelon's proposed license amendment request (LAR) would revise Technical Specifications (TS) requirements to permit the use of Risk-Informed Completion Times (RICT) for actions to be taken when limiting conditions for operation are not met. The proposed changes are based on Technical Specifications Task Force Traveler (TSTF)-505, Revision 2, "Provide Risk Informed Extended Completion Times - RITSTF Initiative 4b," dated July 2, 2018 (ADAMS Package Accession No. ML18269A041 ).

On September 3, 2020, the NRC provided a Request for Additional Information (RAI)

(Reference 2) to support their continued review of Reference 1. On September 16, 2020, the NRC amended its September 3 letter to revise the due dates for its requests for additional information (Reference 3). On October 29, 2020, Reference 4 was submitted in response to Reference 2. On March 1, 2021, the NRC provided EGC with a second round RAI (Reference 5) to support their continued review of Reference 1. EGC's response to Reference 5 was provided in Reference 6.

On April 29, 2021, the NRC provided additional information required to complete its review of Reference 1 in Reference 7. The attachment to this letter contains the NRC's request for additional information along with EGC's response to Reference 7.

EGC has reviewed the information supporting a finding of no significant hazards consideration and the environmental consideration provided to the NRC in Reference 1. The supplemental information provided in this letter does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration. Furthermore, the supplemental information provided in this letter does not affect the bases for concluding that

U.S . Nuclear Regulatory Commission May 10, 2021 Page 3 neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.

There are no regulatory commitments contained in this letter.

Should you have any questions regarding this submittal, please contact Jason Taken at 630-657-3660.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 101h day of May 2021.

Dwi Murray Sr. Manager - Licensing Exelon Generation Company, LLC

Attachment:

Response to Request for Additional Information cc: NRC Regional Administrator, Region Ill NRC Senior Resident Inspector- LaSalle County Station NRC Project Manager, NRR - LaSalle County Station Illinois Emergency Management Agency - Division of Nuclear Safety

ATTACHMENT LaSalle County Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-11 and NPF-18 NRC Docket Nos. 50-373 and 50-374 Response to Request for Additional Information

ATTACHMENT Response to Request for Additional Information EEOB ROUND 3 RAI:

During its review of the LAR and supplemental letters, the staff noted that the information regarding the Design Success Criteria (DSC) in LAR Enclosure 1, Table E1-1 , "In Scope TS/LCO Conditions to Corresponding PRA Functions," is inconsistent with other information in the LAR and Supplements. Specifically, the DSC for TS 3.8.1, Condition B (and referred to for Condition C), states that "one diesel per division" for a unit is necessary for performance of the requisite safety functions. Three diesel generators (DGs) for Divisions 1, 2, and 3 must be available to meet that DSC for a unit experiencing a design basis accident. If any DG for that unit is unavailable for that scenario, for example Division 1 DG, that DSC is not met, and it would be reasonable to conclude that the unit could not safely shutdown. As such, provide additional information that provides the explanation regarding the differences either to confirm the DSC information in Table E1-1 related to the minimum equipment necessary to carry out the safety functions referred to below or provide corrected information.

In LAR Enclosure 1 in Table E1-1, for TS 3.8.1 Condition B under heading Design Success Criteria states, "one diesel per division" and under heading PRA Success Criteria states "Same as Design Success Criteria ."

In LAR Enclosure 1 in Table E1-1 for TS 3.8.1 Condition C for disposition for all table headings states "See 3.8.1.A and 3.8.1.B."

EGC RESPONSE:

EGC confirms that the DSC information provided in Table E1-1 in Enclosure 1 of Reference 1 regarding TS 3.8.1 , Condition B is correct, however, it requires clarification.

Section 8.1.2.2 of the LaSalle Station Updated Final Safety Analysis Report states in part:

The assignment of ESF equipment to the three electrical divisions for each unit is indicated in Table 8.1-1 . The division of the ESF loads among the system buses is such that the total loss of any one of the three electrical divisions cannot prevent the safe shutdown of the reactor under any normal or abnormal design condition.

When describing DSC in the context of Emergency Diesel Generators (EDGs), the current licensing basis requires that each unit needs at least one Division 1 or Division 2 EOG in order to achieve safe shutdown of that unit. EGC's usage of the phrase "one diesel per division" in Table E1-1 was intended to explain that with a Division 1 or Division 2 EOG out of service, the remaining required divisions (i.e., divisions necessary to achieve safe shutdown of the units) would be supported by one Division 1 or Division 2 EOG. Thus, the meaning of "one diesel per division" is understood to be that the remaining required divisions would be supported by an EOG .

To provide additional clarity, the phrase "one diesel per division" may be better construed to mean "one diesel per required division," which remains consistent with the current licensing basis. The DSC remains the same regardless of whether the applicable TS conditions were utilizing a Risk-Informed Completion Time.

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ATTACHMENT Response to Request for Additional Information Accordingly, EGC is providing an update to Table E1-1 regarding TS Condition 3.8.1.B as follows:

LSCS Tech Spec Description SSCs Covered by Modeled Function Design PRA Success Comments Tech TS LCO Condition in PRA Covered by TS Success Criteria Spec LCO Condition Criteria 3.8.1.B One required Division 1 EDGs and their Yes Supply AC One diesel Same as Design SSCs are modeled or 2 DG inoperable OR support systems loads during per Success Criteria consistent with the TS required opposite unit abnormal required scope and so can be Division 2 DG operation division directly included in the inoperable RTR tool for the RICT program. The success criteria are consistent with the desiqn basis The above-bolded text represents the change to Table E1-1 in Enclosure 1 of Reference 1 for the row containing information for TS 3.8.1, Condition B. The superseded information for TS 3.8.1, Condition Bin Table E1-1 does not alter any of the remaining information provided in Reference 1 and its supplements. Therefore, Table E1-1 information for TS 3.8.1 Condition C remains unchanged. As stated previously, a required division is a division that is needed to achieve safe shutdown of the respective unit consistent with the current licensing basis.

REFERENCES:

1. Letter from D. Murray (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "Application to Revise Technical Specifications to Adopt Risk Informed Completion Times TSTF-505, Revision 2, 'Provide Risk- Informed Extended Completion Times - RITSTF Initiative 4b,"' dated January 31, 2020 (ML20035E577).

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