AEP-NRC-2024-48, Response to Request for Additional Information (RAI) for License Amendment Request for One-Time Extension of Completion Time for Inoperable AC Source - Operating

Response to Request for Additional Information (RAI) for License Amendment Request for One-Time Extension of Completion Time for Inoperable AC Source - Operating

ML24184A140
Person / Time
Site:	Cook
Issue date:	07/02/2024
From:	Ferneau K Indiana Michigan Power Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
AEP-NRC-2024-48
Download: ML24184A140 (1)

Text

m INDIANA MICHIGAN l'OfNIR A unit of American Electric Power July 2, 2024 Docket Nos.: 50-315 50-316 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Donald C. Cook Nuclear Plant Unit 1 and Unit 2 Indiana Michigan Power Cook Nuclear Plant One Cook Place Bridgman, Ml 49106 lndianaMichiganPower.com AEP-NRC-2024-48 10 CFR 50.90 Request for Additional Information (RAI) for License Amendment Request for One-Time Extension of Completion Time for Inoperable AC Source - Operating

References:

1. Letter from K. J. Ferneau, Indiana Michigan Power Company (l&M), to U.S. Nuclear Regulatory Commission (NRC), "Donald C. Cook Nuclear Plant Unit 1 and Unit 2 License Amendment Request for One-Time Extension of Completion Time for Inoperable AC Source - Operating,"

dated April 3, 2024, Agencywide Documents Access and Management System (ADAMS)

Accession No. ML24094A288.

2. Letter from S. P. Wall, NRC, to Q. S. Lies, l&M, "Donald C. Cook Nuclear Plant, Unit Nos. 1 and 2 - Supplemental Information Needed for Acceptance of License Amendment Request to Revise Technical Specification 3.8.1 (EPID No. L-2024-LLA-0040)," dated May 7, 2024, ADAMS Accession No. ML24115A215.

3. Letter from K. J. Ferneau, Indiana Michigan Power Company (l&M), to U.S. Nuclear Regulatory Commission (NRC), "Donald C. Cook Nuclear Plant Unit 1 and Unit 2 Supplement to License Amendment Request for One-Time Extension of Completion Time for Inoperable AC Source

- Operating," dated May 16, 2024, ADAMS Accession No. ML24137A221.

4. Email from S. P. Wall, NRC, to M. K. Scarpello, l&M, "Final RAI - D.C. Cook Nuclear Plant, Unit Nos. 1 and 2 - License Amendment Request Regarding Reserve Feed Enclosure (EPID No. L-2024-LLA-0040)," dated May 30, 2024, ADAMS Accession No. ML24156A007.

This letter provides Indiana Michigan Power Company's (l&M), licensee for Donald C. Cook Nuclear Plant (CNP) Unit 1 and Unit 2, response to Reference 4 by the U. S. Nuclear Regulatory Commission (NRC) regarding Reference 1, as supplemented by Reference 3.

U.S Nuclear Regulatory Commission Page 2 AEP-NRC-2024-48 to this letter provides an affirmation statement. Enclosure 2 to this letter provides l&M's response to Reference 4.

The changes proposed in this letter do not impact the conclusions provided in Reference 1 that a finding of "no significant hazards consideration" is justified. There are new regulatory commitments made in this letter. Should you have any questions, please contact Mr. Michael K. Scarpello, Regulatory Affairs Director, at (269) 466-2649.

Sincerely, K~tL~

Site Vice President JMT/sjh

Enclosures:

1. Affirmation

2. Request for Additional Information (RAJ) for License Amendment Request Regarding One-Time Extension of Completion Time for Inoperable AC Source - Operating c:

EGLE - RMD/RPS J.B. Giessner-NRC Region Ill NRC Resident Inspector N. Quilico - MPSC R. M. Sistevaris - AEP Ft. Wayne, w/o enclosures S. P. Wall - NRC Washington, D.C.

A. J. Williamson - AEP Ft. Wayne, w/o enclosures to AEP-NRC-2024-48 AFFIRMATION I, Kelly J. Ferneau, being duly sworn, state that I am the Site Vice President of Indiana Michigan Power Company (l&M), that I am authorized to sign and file this request with the U.S. Nuclear Regulatory Commission on behalf of l&M, and that the statements made and the matters set forth herein pertaining to l&M are true and correct to the best of my knowledge, information, and belief.

Indiana Michigan Power Company

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Site Vice President SWORN TO AND SUBSCRIBED BEFORE ME THIS ~

DAYOF :Su"(

2024

~~~

My Commission Expires S, J ;;l} Jaco 0 to AEP-NRC-2024-48 Page 1 to AEP-NRC-2024-48 Request for Additional Information (RAI) for License Amendment Request Regarding One-Time Extension of Completion Time for Inoperable AC Source - Operating By letter dated April 3, 2024 (Reference 1 ), as supplemented by letter dated May 16, 2024 (Reference 3), Indiana Michigan Power Company (l&M, the licensee) submitted a license amendment request (LAR) for the Donald C. Cook Nuclear Plant (CNP), Units Nos. 1 and 2. The proposed LAR would revise Technical Specification (TS) 3.8.1, "AC Sources - Operating," by adding a footnote for TS 3.8.1, Required Action A.3 to allow a one-time Completion Time (CT) extension from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 288 hours0.00333 days <br />0.08 hours <br />4.761905e-4 weeks <br />1.09584e-4 months <br /> to support the replacement of the 12AB (Train B) Loop Feed Enclosure (LFE) and associated bus for the Train B reserve feed preferred power source.

By email dated May 30, 2024 (Reference 4), the U.S. Nuclear Regulatory Commission (NRC) staff determined that the following information is needed to complete its review.

Regulatory Basis Title 10 Code of Federal Regulations (CFR) Part 50, Section 50.36, "Technical Specifications,"

requires, in part, that the TS shall be included by applicants for a license authorizing operation of a production or utilization facility. 10 CFR 50.36(c) requires that TSs include items in five specific categories related to station operation. These categories are (1) Safety limits, limiting safety system settings, and limiting control settings, (2) Limiting conditions for operation (LCOs) (3)

Surveillance requirements, (4) Design features, and (5) Administrative controls.

The NRC staff's guidance for the review of TSs is provided in chapter 16.0, Technical Specifications," of NUREG-0800, Revision 3, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR [Light-Water Reactor] Edition" (SRP),

March 2010 (ML100351425). The NRC staff uses Branch Technical Position (BTP) 8-8, "Onsite (Emergency Diesel Generators) and Offsite Power Sources Allowed Outage Time Extensions" (ML113640138), to evaluate LARs for one-time or permanent (completion time) extensions for the emergency diesel generators (EDGs) and offsite power sources.

Electrical Engineering Branch (EEEB} Questions

Background

TS 1. 3, "Completion Times, " states:

Limiting conditions for operation (LCOs) specify minimum requirements for ensuring safe operation of the unit. The ACTIONS associated with an LCO state Conditions that typically describe the ways in which the requirements of the LCO can fail to be met. Specified with each stated Condition are Required Action(s) and Completion Time(s).

The Completion Time is the amount of time allowed for completing a Required Action. It is referenced to the time of discovery of a situation (e.g., Inoperable to AEP-NRC-2024-48 equipment or variable not with limits) that requires entering an ACTIONS Condition unless otherwise specified, proving the units is in a MODE or specified condition stated in the Applicability of the LCO.

Required Actions must be completed prior to the expiration of the specified Completion Time.

Page 2 LAR Section 1 states that the proposed change would revise TS 3. 8. 1, *~c Sources - Operating,"

to extend the CT one-time for Required Action A.3 for inoperable offsite circuit from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 288 hours0.00333 days <br />0.08 hours <br />4.761905e-4 weeks <br />1.09584e-4 months <br />. The LAR Section 2. 3 states, in part, that:

... this modification is expected to take approximately 8 days with approximately 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of contingencies. Therefore, a requested one-time allowance of 12 days, or 288 hours0.00333 days <br />0.08 hours <br />4.761905e-4 weeks <br />1.09584e-4 months <br />, is being requested.

SRP BTP 8-8 states, in part, that:

The licensee must provide justification for the duration of the requested AOT

[Allowed Outage Time] (actual hours plus margin based on plant-specific past operating experience).

Note: For the purpose of this RA/, the terms AOT and CT are used interchangeably.

LAR Section 4.2, "Precedents," lists four precedents for similar type outages at other nuclear plants for inoperable offsite circuits for one-time CT extensions but does not provide any operating experience at DC Cook that could support the duration of proposed CT extension. The LAR does not provide the basis and justification to support the 288-hour (12 day) CT extension request. The licensee in the LAR estimated approximately 8 days to complete the modification implementation with contingencies of 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> which equals 10 days. The LAR does not provide the basis and justification for this estimation. In addition, there is a gap between the above 10-day estimation and the requested 12-day CT extension.

EEEB-RAl-1 Please provide a description of the contingencies associated with the proposed CT extension.

Please provide a basis and justification for the duration of the requested 288-hour CT extension that includes time to complete the modification and contingencies.

The basis and justification could be based on the plant operating experience(s), if any.

Please provide an explanation of the time gap between the 10-day estimation and requested 12-day extended CT.

to AEP-NRC-2024-48 l&M's Response to EEEB-RAl-1 Page 3 The contingencies associated with the proposed CT extension include responses to emergent issues associated with the work being performed. This includes the installation of the lugs or stress cones having to be redone (2 lugs, each taking approximately 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> (HRs)), or other unforeseen circumstances, such as inclement weather. In a worst-case scenario, this would necessitate a complete reinstallation of the current configuration in the event the new cable bus cannot be implemented as designed. This effort is estimated to take 4 days to complete and would be realized prior to the completion of the bulk installation outlined in the 120 HRs bullet below.

This modification is a complete redesign and overhaul of the 12AB Loop Feed Enclosure. The best estimation of the work duration is approximately 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br />. This is based on inputs from the vendor and CNP personnel from a variety of groups including, but not limited to, Engineering, Maintenance, Projects, Work Control, and Operations Departments. Although this redesign and overhaul is a first-time evolution, there are portions of this work scope that have been performed previously and operating experience from those occurrences has been taken into consideration.

The extra time requested beyond the current work scope estimation is to account for contingencies due to unforeseen circumstances which may be encountered, up to and including backing out and reinstalling the current configuration. The ten days estimated for the planned modification installation includes the contingency of reinstallation of lugs and stress cones as discussed above. This adds approximately 2 days to the estimated 8 days for the modification installation. The twelve days requested extended CT reflects the worst-case scenario of total reinstallation to the current configuration as it is estimated to take 4 days to restore.

A high-level scope of the work being performed and estimated durations are below:

Enter TS LCO 3.8.1 (Both Operating Units), perform switching to allow placement of clearance on 12-AB and 12-BF switchyard breakers and disconnects. Place grounds on the 12-AB and 12-BF switchyard breaker cables to the 12 AB LFE. Isolate and ground the 1-TR-101AB and the 2-TR-201AB Reserve Aux Transformers - 12 HRs.

Remove the current 12 AB LFE in accordance with the design change: All bus, upper bus duct, and structural steel frame removed. Lower 2000 MCM cable connection to bus enclosure would be removed and 2000 MCM cable stress cones would be removed - 12 HRs.

Install the new 12 AB LFE: This includes the installation of new structural steel which is put into place and aligned to remaining enclosure duct components using a crane, then welded in place. Cut and drill the original remaining duct boxes and install new ducting, divider plates, cable seals - 36 HRs.

Install new cables, lugs, stress cones, which includes the final drilling of bus connections and landing, torquing, and inspecting terminations as required. Each cable is tested prior to lug installation and after lugs are installed, including Tan Delta testing the feed cables from the 12 AB LFE back to the main switchyard. Temporary lifting of grounds will be performed to support cable testing while the equipment is still under clearance - 120 HRs.

to AEP-NRC-2024-48 Page 4 Re-land and torque leads that were lifted for testing and conduct final inspection of the 12 AB LFE-12 HRs.

Release completed modification back to Plant Operations, release and restore clearance and grounding equipment. Restore power to the 12 AB LFE in accordance with the test procedure. Transfer power from the Auxiliary Transformers to the Reserve Feed Transformers for each unit for the final test. Declare Operability and exit Condition A of TS LCO 3.8.1 for both Operating Units - 13 HRs.

PRA (probabilistic risk assessment} Licensing Branch B (APLB) Questions APLB-RAl-1 "Regulatory Guide (RG) 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-informed Decisions on Plant-Specific Changes to the Licensing Basis," January 2018, Rev. 3, (ML17317A256), provides different approaches in the review of deterministic with risk insights versus risk-informed applications. LAR Section 3.0, "Technical Evaluation," indicated that the licensee, in proposing a one-time extension to TS 3.8.1, Condition A.3, applied RG 1.177 "Plant Specific, Risk Informed Decision Making: Technical Specifications," January 2021, Rev. 2, (ML20164A034), by considering engineering issues and applying risk insights. However, LAR Section 4.3, "No Significant Hazards Consideration Determination," indicated that the proposed completion time has been evaluated on a risk-informed basis.

Please clarify whether the licensee intended to submit this LAR as a deterministic with risk insights or a risk-informed application."

l&M's Response to APLB-RAl-1 Reference 1 was submitted as a risk-informed application. In proposing a one-time extension to TS 3.8.1 Required Action A.3 Completion Time, l&M applied Regulatory Guide (RG) 1.177, "Plant-Specific, Risk-Informed Decision-making: Technical Specifications."

RG 1.177 describes acceptable methods for assessing the nature and impact of proposed TS changes, including one-time extensions, by considering engineering issues and applying risk insights. Each of the RG 1.177 principles was addressed in Section 3.0 "Technical Evaluation" of Reference 1.

APLB-RAl-2 "RG 1. 200, Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities,"

December 2020, Rev. 3, (ML202388871) states, in part, that:

F&Os [Facts and Observations] that are not closed using an NRG-endorsed process should be evaluated by the licensee or applicant for their impact on a risk-informed application and addressed with documented justification with necessary changes made to the PRA prior to the use of PRA in the risk-informed application.

to AEP-NRC-2024-48 Page 5 to Enclosure 2 of the LRA indicates that the Fire PRA F&O CFA2-01 (2010 Full Scope) status is partially open. The disposition provided is that the impact is limited to a small portion of the uncertainty analysis due to minor documentation inconsistencies and does not impact the overall technical quality of the Fire PRA.

Please provide a detailed discussion of the hot short probabilities that have not been incorporated, the inconsistencies between the value(s) presented in the documentation and those used in the model(s), and the impact of these uncertainties on this LAR application."

l&M Response to APLB-RAl-2 The original F&O provided in 2010 as part of the full-scope FPRA peer review (L TR-RAM-11 041) identified that the parametric uncertainty of hot short probabilities was not included in the uncertainty analysis. This original evaluation considered SR CF-A2 to be NOT MET. As part of normal model updates to address F&Os, parametric uncertainties for hot short probabilities were identified and applied to the model and documented in the DC Cook Fire PRA uncertainty analysis.

This update was further reviewed for closure as part of the full-scope FPRA F&O closure review performed in 2022 (P3823-0001-02). This review concluded that the majority of circuit failure uncertainties had been applied correctly, and that CF-A2 was MET. However, this review also resolved this F&O as "Partially Open" due to inconsistencies between the modeled and documented parametric uncertainty values. The disposition provided in the F&O closure review provides clarification that the inconsistency is primarily related to cable type identification. Some components that had mixed or unknown cable compositions were assigned thermoset cable uncertainty parameters, when they should have used more conservative thermoplastic cable uncertainty parameters. Review of the issue during the closure review concluded that only the uncertainty parameters are impacted, and that the hot short probabilities used to calculate CDF and LERF are not part of the issue.

Because this F&O is limited only to the parametric uncertainty portion of the model, its resolution would not impact the information contained in the LAR application. The CDF values, LERF values, and risk insights presented in the LAR application use the model's point estimate values, which do not consider parametric uncertainty in their calculation.

PRA Licensing Branch C (APLC) Questions APLC-RAl-1 to enclosure 2 of the LAR indicates that the Seismic PRA F&O 2-1 (2019 FSPR) is open. The disposition provided is that the studies performed in 15C4313-RPT-003 Attachment E show that, while there may be some cracking, it is not widespread at the RLE level.

to AEP-NRC-2024-48 Page 6 Please provide the locations where the 15C4313-RPT-003 study indicates cracking may occur. Additionally, provide a detailed discussion of the impacts on the PRA quantitative

results, defense-in-depth considerations, and identification of risk-significant configurations presented in the LAR if cracking at these locations was accounted for in the seismic model.

l&M Response to APLC-RAl-1 15C4313-RPT-003 performed a sensitivity evaluation to examine the potential for Auxiliary Building cracking. This sensitivity concluded that there would be no cracking at the.5*Response Level Earthquake (RLE) level, and that there would be some localized cracking at the RLE level.

This cracking was present in the spent fuel pool area. This area does not contain any risk-significant components, and therefore the earthquake level would need to be increased considerably beyond the RLE to have a significant impact on plant response. At these higher earthquake levels, the damage to risk-significant structures, system, and components (SSCs) would be sufficiently widespread that the auxiliary building cracking would not become the dominating failure mode, and the risk insights would already be captured under the generic auxiliary building fragility. Based on this assessment, explicit consideration of cracking in the auxiliary building would not impact the PRA quantitative results, defense-in-depth considerations, or identification of risk-significant configurations presented in the LAR.

APLC-RAl-2

Attachment 1 to enclosure 2 of the LAR indicates that the Seismic PRA F&O 28-11 (2018 Full Scope) is open. The disposition provided is that sensitivity studies performed in 15C4313-RPT-003 between uncracked and cracked properties show that structural variability has a minor impact on response compared to the soil property variability. l&M will review the small number of impacted risk-significant components on a case-by-case basis, adjusting frequency range of interest by an additional +/- 15 percent to ensure structural variability is captured in the fragility calculations.

Please provide a detailed discussion of the impacts on the PRA quantitative results, defense-in-depth considerations, and identification of risk-significant configurations presented in the LAR if structural variability is accounted for in the seismic model. "

l&M Response to APLC-RAl-2 The configuration-specific Seismic PRA results were reviewed to identify fragilities that contributed significantly to the model results. These fragilities were then further reviewed to determine if a broadening of their Frequency Range of Interest (FROI) would impact the fragility used to generate the information in the LAR. In certain cases, structural variability was explicitly dispositioned rather than examining the impact of broadening the FROI.

To simplify the dispositions, similar fragilities were grouped together. The list of fragilities and their associated dispositions are presented in the table below.

to AEP-NRC-2024-48 Fragility ID SF-CR-CEIL-1,

-2, -3, -4, -5 SF-SCIB-AB, SF-NSCIB-TB1, SF-SCIB-CONT SF-250DCPNL 1, SF-BATCD SF-LSP, SF-MLOCA, SF-VSLOCA Fragility Description Control Room Ceiling Section 1-5 Auxiliary Building, Turbine Building, and Containment Building fragilities 250 voe Distribution Panel, CD Battery Offsite Power, Medium LOCA, Very Small LOCA Page 7 Disposition of Structural Variability The subject fragilities are Separation of Variable (SoV) calculations developed for collapse of the control room ceiling. As an SoV, different sources of variability have been explicitly considered. In addition, the governing failure mode was identified as resulting from X direction (horizontal) demand, which shows limited variability outside of the considered FROI, and Z direction (vertical) demand which is taken as rigid. Therefore, no changes in fragility would result from consideration of increased structural variability.

The subject fragilities are structural failure or collapse fragilities for the major structures. The F&O is concerning structural stiffness variability in seismic response models and the impact on supported SSCs. Structural failure fragilities are determined based on internal forces and moments which are governed by the fundamental soil and structural frequencies. These are at low frequencies where soil variability has been shown to envelope structural variability.

Therefore, no changes in fragility are necessary to account for structural variability.

The subject fragilities are electrical component fragilities that consider > 8 hertz (Hz) FROI for one or more horizontal directions and rigid for the vertical and other horizontal direction, if applicable.

For each horizontal direction where > 8Hz frequency is considered, a higher frequency peak is included in the seismic demand and would govern even if the FROI was widened by +/- 15 percent (% ).

Therefore, no substantive changes in fragility would result from consideration of increased structural variability.

The subject fragilities are generic fragilities developed based on industry values and engineering judgement. These do not include a fragility analysis using a FROI so no changes are applicable.

to AEP-NRC-2024-48 Page 8 Fragility ID Fragility Description Disposition of Structural Variability SF-SDG Supplemental Diesel Generator System These components are founded on grade, rather than mounted in a Components structure, and therefore are not impacted by structural variability.

The subject fragilities are developed for large groups of equipment SF-SCIC-AB1, SC-I Components in Auxiliary Building - EL. 573'-

based on bounding spectrum capacities and enveloping seismic SF-INV 591', 120VAC Inverter Room demands over building areas. Peak spectral demands are used in all cases, so adjustments to FROI will have no effect on fragilities.

The subject fragility is for CST piping and is found to be governed by an expansion joint with fragility determined for a separate piping system. The expansion joint fragility is developed based on scaling from design documents based on weighted average amplification of SF-CST-PIPE Seismic-Induced Flood from Condensate Storage displacement considering response frequencies and modal Tank (CST) Piping participation factors from the original design documents. Based on the process used and the fact that maximum displacements will occur at lower frequencies where soil variabilities envelope structural variabilities, no changes in fragility are justified to account for structural variability.

The subject fragilities are SoV fragilities for relays that consider a RELAY_D_1, broad FROI, 2 to 40Hz, with In-Structure Response Spectra (ISRS)

RELAY_D_2 Turbine Building and Screenhouse Relay Groups and cabinet amplification factors. Based on the process used and the already broad FROI, no changes in fragility are justified to account for structural variability.

to AEP-NRC-2024-48 RELAY _8_2_U2, RELAY_B_4_U1, RELAY_B_2_U1, I 4KV Switchgear Complex Relay Groups RELAY_B_5_U1 RELAY _B_ 4_U2 Page 9 The subject fragilities are CDFM (Conservative, Deterministic Failure Margin) fragilities that consider cabinet-specific demand amplification using GENRS software. The CDFM considers a broad FROI of 2 to 40 Hz, however the GENRS amplification could be affected by structural frequencies and the cabinet frequencies are at higher frequencies where structural variability could be non-negligible relative to soil variability. With this in mind, the GENRS output was reviewed, and it was generally found that ICRS aligned with structural peaks, and in no cases were adjacent peaks missed by the GENRS process.

Based on this review, no changes in fragility are justified to account for structural variability.

to AEP-NRC-2024-48 Page 10 Overall, for each of the significant fragility contributors identified, consideration of structural variability was concluded to either: 1) Have already been considered, 2) Not impact the method used to estimate the fragility, or 3) not substantively impact the fragility used in the seismic PRA.

Based on the results of this review, further consideration of structural variability would not impact the PRA quantitative results, defense-in-depth considerations, or identification of risk-significant configurations presented in the LAR.

References:

1. Letter from K. J. Ferneau, Indiana Michigan Power Company (l&M), to U.S. Nuclear Regulatory Commission (NRC), "Donald C. Cook Nuclear Plant Unit 1 and Unit 2 License Amendment Request for One-Time Extension of Completion Time for Inoperable AC Source - Operating," dated April 3, 2024, Agencywide Documents Access and Management System (ADAMS) Accession No. ML24094A288.

2. Letter from S. P. Wall, NRC, to Q. S. Lies, l&M, "Donald C. Cook Nuclear Plant, Unit Nos. 1 and 2 - Supplemental Information Needed for Acceptance of License Amendment Request to Revise Technical Specification 3.8.1 (EPID No. L-2024-LLA-0040)," dated May 7, 2024, ADAMS Accession No. ML24115A215.

3. Letter from K. J. Ferneau, Indiana Michigan Power Company (l&M), to U.S. Nuclear Regulatory Commission (NRC), "Donald C. Cook Nuclear Plant Unit 1 and Unit 2 Supplement to License Amendment Request for One-Time Extension of Completion Time for Inoperable AC Source - Operating," dated May 16, 2024, ADAMS Accession No. ML24137A221

4. Email from S. P. Wall, NRC, to M. K. Scarpello, l&M, "Final RAI-D.C. Cook Nuclear Plant, Unit Nos. 1 and 2 - License Amendment Request Regarding Reserve Feed Enclosure (EPID No. L-2024-LLA-0040)," dated May 30, 2024, ADAMS Accession No. ML24156A007.