ML21067A675

NRR E-mail Capture - La Salle Units 1 and 2 - Request for Additional Information (RAI) UHS Amendment Request (EPID-L-2020-LLA-0165)

ML21067A675
Person / Time
Site:	LaSalle
Issue date:	03/08/2021
From:	Bhalchandra Vaidya NRC/NRR/DORL/LPL3
To:	Taken J Exelon Generation Co
References
L-2020-LLA-0165
Download: ML21067A675 (3)

Text

From: Vaidya, Bhalchandra Sent: Monday, March 8, 2021 12:47 PM To: Taken, Jason C.:(Exelon Nuclear); Kusumawatimurray, Putri:(Exelon Nuclear)

Subject:

LA SALLE UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION (RAI)

RE: UHS AMENDMENT REQUEST (EPID-L-2020-LLA-0165)

SUBJECT:

LASALLE UNITS 1 AND 2 -REQUEST FOR ADDITIONAL INFORMATION (RAI) RE: REQUEST FOR LICENSE AMENDMENT REGARDING ULTIMATE HEAT SINK, (EPID-L-2020-LLA-0165)

Jason and Dwi, By letter to the U.S. Nuclear Regulatory Commission (NRC) dated July 17, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20204A775), as supplemented by letters dated September 11, October 22, 2020 (ADAMS Accession No. ML20259A454 and ML20296A456, respectively), Exelon Generation Company, LLC (EGC, the licensee) submitted a request to amend Technical Specification 3.7.3, "Ultimate Heat Sink," for the LaSalle County Station, Units 1 and 2, to expand the TS temperature limit of the cooling water supplied to the plant from the UHS to vary with the diurnal cycle by changing the average sediment level limit in the UHS to 6 inches.

The U.S. Nuclear Regulatory Commission (NRC) staff currently reviewing your submittals. The NRC staff has identified areas where additional information is needed to complete its review. The Draft Request For Additional Information (RAI) is provided below.

Subsequent to the clarification telephone conference on March 3, 2021, by email dated March 8, 2021, you have committed to provide the responses to these RAIs no later than 30 Calendar days from the date of this transmittal.

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REQUEST FOR ADDITIONAL INFORMATION OFFICE OF NUCLEAR REACTOR REGULATION Exelon Generation Co., LLC DOCKET NOS. 50-373, AND 50-374 EPID: L-2020-LLA-0165 Regulatory Basis 10 CFR 50, Appendix A, General Design Criteria (GDC) 13, Instrumentation and control, requires, in part, that instrumentation shall be provided to monitor variables and systems over their anticipated ranges for normal operation, for anticipated operational occurrences, and for accident conditions as appropriate to assure adequate safety.

10 CFR 50.36, "Technical Specifications," paragraph (c)(2)(ii), Criterion 3, requires Technical Specification Limiting Conditions for Operation (TS LCO) be established for each item meeting one or more of the following criteria:

Criterion 3. A structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier.

Request for Additional Information: RAI EICB - 1 The license amendment request expands the already-approved TS temperature limit of the cooling water supplied to the plant from the UHS to vary with the diurnal curve by changing the average sediment level limit in the intake flume and UHS from 18 inches to 6 inches. The result is an increase in UHS effective volume, according to the application, of 24% which decreases temperature response due to the increased volume. The adjusted TS Figure 3.7.3-1 is based on the following equation:

Maximum peak cooling water temperature - Transient Heat-up Rate - Instrument Uncertainty* - 0.25°F adjustment = Adjusted Initial UHS Temperature

• In the application, the Instrument Uncertainty is stated as 0.75°F.

Provide the technical basis for the proposed values used to calculate the limits for the peak initial UHS temperature. Specifically, discuss how the reduction in "additional margin" used to calculate the peak initial UHS temperature is sufficient to ensure the maximum temperatures do not exceed the safety analysis limit and justify the reduction of margin from 0.42°F to 0.25°F. Discuss the methodology used to calculate the "instrument uncertainty" and if it is still bounded by the increased operating temperatures to ensure the maximum temperatures do not exceed the safety analysis limit. The staff needs this information to verify the adequacy of the calculation and compliance with GDC 13 and 10 CFR 50.36.

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Please contact me, if you have any questions.

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: 1060 Mail Envelope Properties (SJ0PR09MB7216653AA7AB412969FA041B8D939)

Subject:

LA SALLE UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION (RAI) RE: UHS AMENDMENT REQUEST (EPID-L-2020-LLA-0165)

Sent Date: 3/8/2021 12:46:48 PM Received Date: 3/8/2021 12:46:48 PM From: Vaidya, Bhalchandra Created By: Bhalchandra.Vaidya@nrc.gov Recipients:

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

Tracking Status: None "Kusumawatimurray, Putri:(Exelon Nuclear)" <Putri.Kusumawatimurray@exeloncorp.com>

Tracking Status: None Post Office: SJ0PR09MB7216.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 4274 3/8/2021 12:46:48 PM Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date: