ML25077A182

– Issuance of Amendment No. 352 Calvert Cliffs Emergency One Time Extension of TS 3.7.8.C (Emergency Circumstances)

ML25077A182
Person / Time
Site:	Calvert Cliffs   (DPR-053, DPR-069)
Issue date:	03/18/2025
From:	Bina S Plant Licensing Branch 1
To:	Rhoades D Constellation Energy Generation
Marshall, Michael
References
EPID L-2025- LLA-0049
Download: ML25077A182 (1)

Text

March 18, 2025 David P. Rhoades Senior Vice President Constellation Energy Generation, LLC President and Chief Nuclear Officer Constellation Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT 1 - ISSUANCE OF AMENDMENT NO. 352 RE: CALVERT CLIFFS EMERGENCY ONE TIME EXTENSION OF TS 3.7.8.C (EMERGENCY CIRCUMSTANCES) (EPID L-2025-LLA-0049)

Dear David Rhoades:

The U.S. Nuclear Regulatory Commission (NRC or the Commission) has issued the enclosed Amendment No. 352 to Renewed Facility Operating License No. DPR-53 for the Calvert Cliffs Nuclear Power Plant, Unit 1. This amendment consists of changes to technical specifications (TSs) in response to your application dated March 15, 2025, as supplemented by letter dated March 17, 2025.

The amendment approves a one-time extension and additional actions to TS 3.7.8, Control Room Emergency Ventilation System (CREVS), Action C.1 Completion Time, from 7 days to 17 days, for one train of the CREVS that is inoperable because of the emergency power supply for the train being inoperable. The one-time extension supports ongoing modifications and return to service testing of the 13.8 kV Service Bus 21.

The license amendment is issued under emergency circumstances as provided in paragraph 50.91(a)(5) of Title 10 of the Code of Federal Regulations because of the time-critical nature of the amendment. In this instance, an emergency situation exists in that the amendment is needed to allow the licensee to avoid a plant shutdown.

The NRC staffs related safety evaluation is also enclosed. The safety evaluation describes the emergency circumstances under which the amendment is issued and the NRCs final no significant hazards determination. A Notice of Issuance addressing the final no significant hazards determination and an opportunity for a hearing associated with the issuance of these amendments under emergency circumstances will be included in the Commissions monthly Federal Register notice.

Sincerely,

/RA/

Samuel Bina, Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-317

Enclosures:

1. Amendment No. 352 to DPR-53

2. Safety Evaluation cc: Listserv

CONSTELLATION ENERGY GENERATION, LLC DOCKET NO. 50-317 CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT 1 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 352 Renewed License No. DPR-53

1.

The U.S. Nuclear Regulatory Commission (the Commission) has found that:

A.

The application for amendment by Constellation Energy Generation, LLC (the licensee) dated March 15, 2025, as supplemented by letter dated March 17, 2025, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act) and the Commissions rules and 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 rules and 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 Commissions regulations; 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 Commissions regulations and all applicable requirements have been satisfied.

2.

Accordingly, the license is amended by changes to the renewed facility operating license and technical specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Renewed Facility Operating License No. DPR-53 is hereby amended to read as follows:

(2)

Technical Specifications The Technical Specifications contained in Appendices A and B, as revised through Amendment No. 352 are hereby incorporated into this license. Constellation Energy Generation, LLC shall operate the facility in accordance with the Technical Specifications.

3.

This license amendment is effective as of the date of its issuance and will be implemented immediately.

FOR THE NUCLEAR REGULATORY COMMISSION Hipólito González, Chief Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Renewed Facility Operating License and Technical Specifications Date of Issuance: March 18, 2025 HIPOLITO GONZALEZ Digitally signed by HIPOLITO GONZALEZ Date: 2025.03.18 17:01:37 -04'00'

ATTACHMENT TO LICENSE AMENDMENT NO. 352 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-53 CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT 1 DOCKET NO. 50-317 Replace the following pages of Renewed Facility Operating License No. DPR-53, and Appendix A, Technical Specifications (TSs), with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change.

Renewed Facility Operating License No. DPR-53 REMOVE INSERT 3

3 Technical Specifications REMOVE INSERT 3.7.8-2 3.7.8-2 Amendment No. 352 (4)

Constellation Energy Generation, LLC, pursuant to the Act and 10 CFR Parts 30, 40, and 70, to receive, possess, and use, in amounts as required, any byproduct, source, and special nuclear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; and (5)

Constellation Energy Generation, LLC, pursuant to the Act and 10 CFR Parts 30 and 70, to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility.

C.

This license is deemed to contain and is subject to the conditions set forth in 10 CFR Chapter I and is subject to all applicable provisions of the Act, and the rules, regulations, and orders of the Commission, now or hereafter applicable; and is subject to the additional conditions specified and incorporated below:

(1)

Maximum Power Level Constellation Energy Generation, LLC is authorized to operate the facility at steady-state reactor core power levels not in excess of 2737 megawatts-thermal in accordance with the conditions specified herein.

(2)

Technical Specifications The Technical Specifications contained in Appendices A and B, as revised through Amendment No. 352, are hereby incorporated into this license.

Constellation Energy Generation, LLC shall operate the facility in accordance with the Technical Specifications.

(a)

For Surveillance Requirements (SRs) that are new, in Amendment 227 to Facility Operating License No. DPR-53, the first performance is due at the end of the first surveillance interval that begins at implementation of Amendment 227. For SRs that existed prior to Amendment 227, including SRs with modified acceptance criteria and SRs whose frequency of performance is being extended, the first performance is due at the end of the first surveillance interval that begins on the date the Surveillance was last performed prior to implementation of Amendment 227.

(3)

Additional Conditions The Additional Conditions contained in Appendix C as revised through Amendment No. 345 are hereby incorporated into this license.

Constellation Energy Generation, LLC shall operate the facility in accordance with the Additional Conditions.

CREVS 3.7.8 CALVERT CLIFFS - UNIT 1 3.7.8-2 CALVERT CLIFFS - UNIT 2 Amendment No. 352 Amendment No. 299 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME B.

One or more CREVS trains inoperable due to inoperable CRE boundary in MODE 1, 2, 3, or 4.

B.1 Initiate action to implement mitigating actions.

AND B.2 Verify mitigating actions ensure CRE occupant exposures to radiological, chemical, and smoke hazards will not exceed limits.

AND B.3 Restore CRE boundary to OPERABLE status.

Immediately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 90 days C.

One CREVS train inoperable for reasons other than Condition A or B in MODE 1, 2, 3, or 4.

C.1 Restore CREVS train to OPERABLE status.

7 days

• This Action is extended for Unit 1 from 7 days to 17 days during electrical modifications and restoration work associated with the 13.8 kV Bus 21. The one-time extension will remain in effect until March 29, 2025 at 06:16 EDT or until the 12 CREVS train is returned to OPERABLE status, whichever occurs sooner. Compensatory measures detailed within Constellation Energy Generation, LLC letter dated March 15, 2025, including the updated "Protected Equipment for 12 CREV OOS" detailed within Constellation Energy Generation, LLC letter dated March 17, 2025, shall be implemented and shall remain in effect during the extended Completion Time period.

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 352 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-53 CONSTELLATION ENERGEY GENERATION, LLC CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT 1 DOCKET NO. 50-317

1.0 INTRODUCTION

1.1 Background

By letter dated March 15, 2025, (Agencywide Documents Access and Management System Accession No. (ADAMS) ML25074A002, supplemented by letter dated March 17, 2025 (ML25076A675)), Constellation Energy Generation, LLC (the licensee) requested changes to the technical specifications (TS) for Calvert Cliffs Nuclear Power Plant (CCNPP), Unit 1.

CCNPP, Units 1 and 2, have a common control room. The CREVS is a shared system that consists of two redundant trains. Limiting Condition for Operation LCO 3.7.8 requires that two CREVS trains shall be OPERABLE during MODES 1, 2, 3, 4, and during movement of irradiated fuel assemblies, but also states that only one CREVS redundant component is required to be OPERABLE during movement of irradiated fuel assemblies when both Units are in MODE 5 or 6, or defueled; only one CREVS train is required to be OPERABLE for the movement of irradiated fuel assemblies; and the control room envelope (CRE) boundary may be opened intermittently under administrative control.

The proposed changes would allow a one-time extension to the Completion Time (CT) for TS 3.7.8, Control Room Emergency Ventilation System (CREVS), Required Action C.1 from 7 days to 17 days with additional compensatory actions being required. The licensee stated the one-time extension is necessary to support ongoing modifications and return to service testing of the 13.8 kV Service Bus 21, which is projected to challenge the current CREVS completion time of 7 days.

1.2 Description of CREVS Power Supply According to the licensing amendment request (LAR), Attachment 1, Section 2.1, CREVS Design and Operation, the 12 CREVS train receives power from Unit 2 through 4.16 kilovolt (kV) Bus 24, with the 2B Diesel Generator (DG) as the emergency power supply. With either Unit in Modes 1 through 4, the limiting condition for operation (LCO) for TS 3.7.8 requires both trains of the CREVS to be operable. TS 3.7.8 Condition C describes the situation where at least one unit is in MODE 1, 2, 3, or 4 and one train of CREVS is inoperable for reasons other than an

inoperable toilet area exhaust isolation valve or an inoperable CRE boundary. Required Action C.1 requires restoration of the inoperable CREVS train within 7 days. If the CREVS system is not restored to OPERABLE status within 7 days, TS 3.7.8 Condition G and Actions G.1 and G.2 requires both CCNPP units be in MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, respectively.

1.3 Reason for Proposed Change As stated in the LAR, the licensee is performing scheduled upgrades to the electrical distribution system. CCNPP, Unit 2, is in MODE 5 for a planned refueling outage, Unit 1 is in MODE 1. On March 9, 2025, at 06:16 hours Eastern Daylight Time (EDT), in accordance with the licensees scheduled plan, CCNPP, Unit 1, entered TS 3.8.1 Condition D for less than two off site power supplies available while 13.8 kV Service Bus 21 was deenergized for maintenance. After 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, on March 12, 2025, at 06:16 hours EDT, CCNPP, Unit 1, entered TS 3.7.8, Condition C for one CREVS train inoperable (the 12 CREVS train). The licensee stated that the scheduled upgrade work prevents the restoration of 13.8 kV Service Bus 21 until the scheduled upgrades are completed. This means the 12 CREVS train will remain inoperable until after 13.8 kV Service Bus 21 is restored. As stated by the licensee in the LAR, Attachment 1, Section 2.3, there have been multiple delays in the upgrades. The licensee estimates that restoration of 13.8 kV Service Bus 21 and subsequent restoration of the 12 CREVS train to OPERABLE status may take up to an additional 10 days. Therefore, the licensee requests a one-time CT extension from 7 to 17 days, to prevent the shutdown of CCNPP, Unit 1.

1.4 Proposed TS 3.7.8 Changes The licensee proposed to add a footnote (denoted by an asterisk (*)) to modify the CT of TS Required Action 3.7.8.C.1 as follows (changes are indicated by bold type):

CONDITION REQUIRED ACTION COMPLETION TIME C. One CREVS train inoperable for reasons other than Condition A or B in MODE 1, 2, 3, or 4.

C.1 Restore CREVS train to OPERABLE status.

7 days*

• This Action is extended for Unit 1 from 7 days to 17 days during electrical modifications and restoration work associated with the 13.8 kV Bus 21. The one-time extension will remain in effect until March 29, 2025 at 06:16 EDT or until the 12 CREVS train is returned to OPERABLE status, whichever occurs sooner. Compensatory measures detailed within Constellation Energy Generation, LLC letter dated March 15, 2025, including the updated "Protected Equipment for 12 CREV OOS" detailed within Constellation Energy Generation, LLC letter dated March 17, 2025, shall be implemented and shall remain in effect during the extended Completion Time period.

2.0 REGULATORY EVALUATION

The U.S. Nuclear Regulatory Commission (NRC or the Commission) staff considered the LAR against the following regulatory requirements and design basis.

2.1 Requirements Under Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Section 50.92(a),

determinations on whether to grant an applied-for license amendment are to be guided by the considerations that govern the issuance of initial licenses to the extent applicable and appropriate.

Both the common standards for licenses in 10 CFR 50.40(a) (regarding, among other things, consideration of the operating procedures, the facility and equipment, the use of the facility, and other technical specifications, or the proposals) and those specifically for issuance of operating licenses in 10 CFR 50.57(a)(3), provide that there must be reasonable assurance that the activities at issue will not endanger the health and safety of the public, and that the applicant will comply with the Commission's regulations. 10 CFR 50.36, Technical specifications, requires, in part, that the operating license of a nuclear production facility include TS. Paragraph 50.36 (c)(2)(i) of 10 CFR requires that the TSs include LCOs, which are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When an LCO of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the TSs until the condition can be met. The remedial actions specified in the TS must provide the requisite reasonable assurance of public health and safety described in 10 CFR 50.40 and 50.57.

As part of LAR, the licensee proposed additional remedial actions as part of its proposed extension to the restoration time.

2.2 Design Basis Appendix General Design Criteria for Nuclear Power Plants, to 10 CFR Part 50, General Design Criterion (GDC) 17, Electric power systems, requires, in part, that an onsite electric power system and an offsite electric power system shall be provided to permit the functioning of structures, systems, and components important to safety. The safety function for each system (assuming the other system is not functioning) shall be to provide sufficient capacity and capability to assure that (1) specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents.

Appendix A to 10 CFR Part 50, GDC 19, Control room, requires, in part, that a control room shall be provided from which actions can be taken to operate the nuclear power unit safely under normal conditions and to maintain it in a safe condition under accident conditions, including loss-of-coolant accidents.

The NRC staff notes that CCNPP was not licensed to the GDCs listed in 10 CFR Part 50, Appendix A, but was licensed based on the Atomic Energy Commission- (AEC) proposed Principal Design Criteria (PDCs) published on July 10, 1967. The relevant principal design criteria for CCNPP are described in Appendix 1C of the Calvert Cliffs Updated Final Safety Analysis Report (UFSAR) (ML23250A368) and are as follows:

Similar to GDC 17, UFSAR Appendix 1C.5 and 1C.8 include Criteria 24 and 39, respectively.

Criterion 24, Emergency Power for Protection Systems (Category B), states that in the event of loss of all offsite power, sufficient alternate sources of power shall be provided to permit the required functioning of the protection systems.

Criterion 39, Emergency Power for Engineered Safety Features (Category A), states that alternate power system shall be provided and designed with adequate independency, redundancy, capacity, and testability to permit the functioning required of the engineered safety features. As a minimum, the onsite power system and the offsite power system shall each, independently, provide this capacity assuming a failure of a single active component in each power system.

Similar to GDC 19, UFSAR Appendix 1C.4 includes Criterion 11, Control Room (Category B), which states:

The facility shall be provided with a control room from which actions to maintain safe operational status of the plant can be controlled. Adequate radiation protection shall be provided to permit access, even under accident conditions, to equipment in the control room or other areas as necessary to shut down and maintain safe control of the facility without radiation exposures of personnel in excess of 10 CFR Part 20 limits. It shall be possible to shut the reactor down and maintain it in a safe condition if access to the control room is lost due to fire or other cause.

3.0 TECHNICAL EVALUATION

3.1 Deterministic Evaluation The NRC staffs deterministic evaluation of the proposed change considered various potential plant conditions that could be encountered while exercising the one-time CT extension. The NRC staff also considered the available redundant equipment to respond to various plant conditions.

3.1.1 Evaluation of CREVS Capacity The NRC staff reviewed the licensees safety analysis provided in Section 3.1 of Attachment 1 to the LAR. The CCNPP UFSAR describes the two redundant emergency ventilation subsystems for the control room. The safety function of the CREVS is to maintain the control room habitable for operators and to maintain the environment needed for continued equipment operation. The CREVS uses fans, dampers, and filters to accomplish its safety functions. To allow for a single failure to the system, the control room is served by two redundant 100 percent capacity CREVS trains. Each of the CREVS trains is powered from a different safety-related bus, which is powered from different DGs.

A CREVS train is considered operable when the associated components listed below are operable and their associated power supplies are operable:

• Control Room Heating, Ventilation, and Air Conditioning Supply and Return;

• Post Loss-of-Coolant Incident (LOCI) fan;

• Post LOCI filter train;

• High Efficiency Particulate Air (HEPA) filters;

• Ductwork, valves, and dampers; and

• CRE boundary (the single boundary supports both subsystems).

Per TS Required Action 3.7.8.C.1, CCNPP may remove one of the CREVS trains from service for up to 7 days to provides a limited time to make modifications, repair equipment, or conduct testing.

Seven days was based on the low probability of a design basis accident occurring during this time

period, and the ability of the remaining train to provide the required capability. During the proposed one-time extended CT, the primary offsite power supply for 12 CREVS, the 13.8 kV Bus 21, will be inoperable while modifications and testing are performed.

The 12 CREVS train does not directly impact core damage frequency or large early release frequency but does support the control room envelope safe haven for operators to control the plant during postulated radiological, smoke, or other toxic gas events. Furthermore, the 12 CREVS train will be functional during the period of the extended completion time since the 12 CREVS train will be powered from its alternate offsite power supply and have emergency onsite power supply available, as discussed in section 3.1.2 of this safety evaluation.

The licensee stated that two predominant ways that offsite power could be inadvertently lost are through maintenance activities and weather-related events. As detailed in the licensees March 15, 2025, LAR, Attachment 1, Section 3.2, Risk Assessment Insights and Compensatory Measures, in order to reduce the possibility that maintenance activities could contribute to a loss of offsite power, the protected equipment to prevent 11 CREVS being declared INOPERABLE includes 11 CR HVAC, 1A DG, and the 2B DG which is the emergency supply to the 12 CREVS. The main control room has placed protected equipment tags on the hand switch for 13 kV Bus (11) and will continue to protect the single 13 kV / 4 kV transformer (U-4000-12), including the 4 kV Bus 11 for 11 CREVS/Control Room Emergency Temperature System (CRETS). CCNPP will continue to implement Risk Management Actions (RMAs) associated with LCO 3.8.1 Condition A for the Risk Informed Completion Time (RICT) program. This will provide additional margin beyond the two transmission lines required by TS.

As far as weather-related events, the licensee assessed the vulnerability to tornadoes and hurricanes on the design and construction of the four transmission lines. The probability of tornadoes and hurricanes striking Calvert Cliffs were previously evaluated for the Station Blackout rule response. The frequencies reported were 3.75 x 10-4 per year for tornadoes, and 0.1 per year for hurricanes. Although winter ice storms are another potential threat to the transmission system, these are not likely due to the current forecast for the timeframe involved. The licensee stated that based on the robust design of the transmission system and the current electrical configuration, which has two of the four offsite power sources available, the vulnerability of the transmission system to a weather-related event is minimized and acceptable.

During the electrical upgrade maintenance window in which the 4 kV Bus 11 (power to 11 CREVS) is protected, some work will be required on the bus. Specifically, wiring will be required on the alternate feeder breaker for the 4 kV Bus 11. This breaker is on the bus and will be open as the normal feeder will be supplying power to the bus. This will be approved by the protected equipment procedure (OP-AA-108-117) and require a targeted pre-job brief, supervisor oversight in the field and periodic monitoring by an Operations Supervisor. Additionally, this work screens as Elevated Risk per the Integrated Risk Management procedure (OP-AA-107). A risk mitigation plan (RMP) will also be required to specify actions required to mitigate any potential errors. This action further reduces the overall risk since all five DGs are currently available.

In addition, as detailed in Section 3.2 of Attachment 1 to the LAR, and Section 3.1.4 of this safety evaluation, CCNP will protect and restrict planned maintenance on the 11 CREVS train and the 1A DG and associated support systems to ensure the 11 CREVS train remains operable while the 12 CREVS train does not have an independent off-site power source.

The licensee stated that if an unforeseen circumstance causes the loss-of-emergency power to the 11 CREVS train while in this condition, the site will follow the appropriate action statement for the loss of both CREVS trains and that the proposed one-time extension has no effect on the

completion times for the Action Statement associated with LCO 3.7.8 Condition D for the loss of both CREVS trains.

Based on the information provided by the licensee and the evaluation above, the NRC staff finds with reasonable assurance that CREVS will remain capable of performing its safety functions to support safe shutdown of the plant and mitigation of the effects of a design-basis accident for the duration of the extended completion time.

3.1.2 Evaluation of Electrical Power Sources for CREVS The NRC staff reviewed information pertaining to the CREVS and its power sources in the application, the UFSAR, applicable TS LCO and TS Bases to verify the capability of the power sources for the CREVS to perform its safety functions (assuming no additional failures of CREVS components and its power sources) is maintained.

Offsite Power Sources The LAR states, in part, that the CCNPP offsite power system consists of three independent 500-kV transmission lines with a common switchyard, and a separate 69-kV transmission line that connects to the 13-kV buses. One of the 500-kV lines is out of service for planned maintenance and the 69-kV transmission line is not currently available as an offsite power source. In the current electrical line up, CCNPP has two of the four offsite power sources available (5051 and 5052).

These sources are being supplied to downstream 4-kV buses through a single 13-kV Bus (11) and a single 13-kV/4-kV transformer (U-4000-12), including the 4-kV Bus (24) for the 12 CREVS/CRETS (Control Room Emergency Temperature System).

Onsite Power Sources Chapter 8 of the CCNPP UFSAR states that the plant has four safety-related emergency DGs (1A, 1B, 2A, and 2B), two dedicated to each unit. Any combination of two of the emergency DGs (one from each unit) is capable of supplying sufficient power for the operation of necessary engineered safety feature (ESF) loads during accident conditions on one unit and shutdown loads of the alternate unit concurrent with a loss of offsite power (LOOP) and for the safe and orderly shutdown of both units under LOOP conditions. The emergency DGs start automatically on safety injection actuation signal (SIAS) or an undervoltage condition on the busses which supply vital loads and are ready to accept loads within 10 seconds. A Station Blackout DG (0C DG) can also be aligned to any of the four ESF busses. According to the LAR, all five emergency DGs are currently available.

CREVS Power Sources As stated in the LAR dated March 15, 2025, and its supplement dated March 17, 2025, the 11 CREVS train is normally powered from the Unit-1 4-kV ESF Bus 11, which is connected to the 13-kV Service Bus 11 offsite circuit and backed up by the 1A DG. The 12 CREVS train is normally powered from the 13-kV Service Bus 21, through the U-4000-22 transformer and the 4-kV ESF Bus 24, and backed up by the 2B DG.

During the proposed extended CT, the primary offsite power supply for 12 CREVS, the 13-kV Bus 21, will be inoperable for up to 30 days in accordance with the RICT while modifications and testing are performed. In the current alignment to support refueling outage work, the 12 CREVS train is being powered from the Unit-1 13-kV Service Bus 11. This electrical alignment for the 12

CREVS train is through the U-4000-12 transformer and the 4-kV ESF Bus 24 and is backed up by the 2B DG. The LAR further states that the 12 CREVS train has its emergency onsite power supply, the 2B DG, available during this period. The non-safety related 0C DG is available as a backup emergency power source for the 12 CREVS. In the event of failure of the 0C DG, the 12 CREVS train can be powered by tying lower-level buses in accordance with existing approved site operating procedures.

Regarding the protection of the 11 CREVS train during the proposed extended CT, the LAR and its supplement state that to reduce the possibility that maintenance activities could contribute to a LOOP during the proposed extended CT, the equipment will be protected to prevent the 11 CREVS train being declared INOPERABLE includes Control Room HVAC (11), 1A DG, and 2B DG which is the emergency supply to the 12 CREVS train. The main control room has placed protected equipment tags on the hand switch for 13-kV Bus 11 and will continue to protect the single 13-kV/4-kV transformer (U-4000-12), including the 4-kV Bus 11 for 11 CREVS train. The site will continue to implement Risk Management Actions (RMAs) associated with LCO 3.8.1 Condition A for the RICT program. In addition, systems and components significant to this LAR and its supplements will be protected and only critical non-discretionary work will be performed on those systems and components in accordance with overall safety considerations. The detailed evaluation of the compensatory measures is described in Section 3.1.4 of this safety evaluation.

The NRC staff reviewed the proposed one-time change to CCNPP TS 3.7.8 pertaining to the power sources for the CREVS trains and the proposed actions for preventing the 11 CREVS train from becoming INOPERABLE. Based on the information provided by the licensee, the NRC staff finds that during the proposed one-time extended CT period, while the redundancy of the power source for the 12 CREV train is temporarily reduced, the minimum capacity and capability of the electrical power sources (i.e., 2B DG, 0C DG, and lower-level buses) to provide power to the 12 CREVS train in an event of LOOP is maintained (assuming no additional failures of electrical components).

The NRC staff also finds that the proposed compensatory measures that are incorporated into the action statement of the amended technical specification are adequate to help ensure the availability of the power sources for the 11 CREVS train during the proposed one-time CT extension for the 12 CREVS train.

3.1.3 Evaluation of Proposed Change to TS 3.7.8 The staff reviewed the licensees proposed footnote for the current 7-day CT for TS 3.7.8 Condition C. The staff determined that the language of the footnote restricts the extension of the CT for Required Action C.1 to CCNP, Unit 1, alone and the extension will only be applicable during the specific set of circumstances related to the electrical distribution system work described in the LAR. The staff determined that the language of the footnote also requires the compensatory measures, described in the March 15, 2025, and March 17, 2025, application letter and supplement, to remain in place during the extension. As discussed in detail in section 3.1.4 of this SE, the staff determined that the compensatory measures are an appropriate supplement to the remedial measures the licensee must take while the LCO is not met during the extended CT.

Therefore, the NRC staff finds the proposed TS changes will provide reasonable assurance of public health and safety.

3.1.4 Evaluation of Compensatory Measures In the LAR, as supplemented, the licensee described compensatory measures that will be part of the required actions in the amended technical specifications. These are summarized below.

Continue to implement RMAs associated with LCO 3.8.1 Condition A for the RICT Program.

Continue to implement the protected equipment program in accordance with the Maintenance Rule (a)(4) program based on the active maintenance configurations. For the unique configuration when the 12 CREV is out of service (OOS), equipment protected is listed below.

11 CR HVAC (fan housing, condenser breaker, compressor breaker, and fan hand switch 1A DG (CR console and DG room) 2B DG (CR console and DG room) 0C DG (CR console and DG room) 500 kV Breakers 552-22, 552-41, 552-43, 552-21, 552-23, and control room hand switches 500 kV Switchyard Control House 13 kV Bus 11 (Unit 1 metal clad enclosure and all enclosed breakers (including feeder breaker) and CR feeder breaker hand switch)

U-4000-11 13/4 kV Transformer (transformer, feeder breaker, and CR feeder breaker hand switch)

U-4000-12 13/4 kV Transformer (transformer, feeder breaker, and CR feeder breaker hand switch) 4 kV Bus 11 (feeder breaker and CR feeder breaker hand switch) 4 kV Bus 24 (feeder breaker and CR feeder breaker hand switch) 12 Condensate Storage Tank (CST) 1BKR252-1201 U1 RCP Bus Feeder Breaker 11 Demin Water Storage Tank (DWST) 11 SW HDR 11B 480V Load Center / Service XFRMR If AFW Pump 23 is unavailable or becomes unavailable during the extended CT window, protect AFW Pumps 11, 12, and 13.

Brief Operator Actions RCP Trip Strategy Identify and Diagnose Steam Generator Level Align 120 VAC Panel to Back-Up Bus Control AFW Flow Cross-Connect Reactor MCCs Protect Fire Areas 27ft Unit-1 Switchgear Room The NRC staff reviewed the above compensatory measures with respect to the defense-in-depth aspects. Based on its review, the NRC staff finds that these compensatory measures will provide reasonable assurance for the duration of the extended CT interval for the 12 CREVS train that (1) the availability of the 11 CREVS train is maintained, (2) the risk of the plant transients is reduced, (3) operation, testing, and maintenance of the plant equipment will be minimized to avoid an adverse impact on plant operations, (4) systems and components significant to this LAR and its supplements will be protected and only critical non-discretionary work will be performed on those systems and components in accordance with overall safety considerations, and (5) main control room operators will be specifically alerted to the ongoing maintenances.

3.1.5 Deterministic Conclusion The NRC staff reviewed the proposed one-time change to CCNPP TS 3.7.8. The proposed change would revise TS 3.7.8, Required Action C.1, by inserting a note that allows Unit 1 a one-time CT extension for the 12 CREVS train from 7 days to 17 days. Based on the above evaluations, the NRC staff finds that during the proposed one-time extended CT period, the minimum capacity and capability of the CREVS is maintained (assuming no additional failures). In addition, the NRC staff finds that the proposed compensatory measures are adequate to help ensure the availability of the 11 CREVS train during the proposed one-time CT extension for the 12 CREV train is maintained (assuming no additional failures). In addition, the NRC staff finds that the proposed compensatory measures are adequate to help ensure the availability of the 11 CREVS train during the proposed one-time CT extension for the 12 CREV train.is maintained (assuming no additional failures). In addition, the NRC staff finds that the proposed compensatory measures are adequate to help ensure the availability of the 11 CREVS train during the proposed one-time CT extension for the 12 CREVS train.

3.2 Risk Insight Evaluation While this is not a risk-informed LAR, the licensee provided risk insights related to the proposed change in Section 3.2 of Attachment 1 to the LAR. The licensee stated that the 12 CREVS train does not directly impact core damage frequency (CDF) or large early release frequency (LERF) in the CCNPP Probabilistic Risk Assessment (PRA) models, and the impact of the CREVS being unavailable is considered a negligible contribution to the CDF or LERF risk. The licensee also stated that the CREVS is not credited with smoke removal in the Fire PRA model. In a postulated fire event that could impact control room habitability, shutdown of the plant can be achieved from outside of the control room. Since this is not a risk-informed LAR, the above-mentioned PRA models used by the licensee to derive the risk insights were not reviewed by the NRC staff to determine their technical acceptability to support this safety evaluation.

The NRC staff considered the licensee-provided risk insights and associated risk management actions (RMAs) to aid the deterministic review of the proposed change. The RMAs include:

Protecting Fire Area 27ft Unit-1 Switchgear Room.

Protecting appropriate equipment to reduce the possibility that maintenance activities could contribute to a loss-of-offsite power and 11 CREVS being declared INOPERABLE.

Implementing targeted pre-job brief, supervisor oversight in the field, and periodic monitoring by an Operations Supervisor in accordance with licensees protected equipment procedure OP-AA-108-117.

Implementing RMA associated with LCO 3.8.1 Condition A for the RICT program, which provides additional margin to prevent a loss of offsite power due to maintenance.

Implementing the protected equipment program in accordance with the Maintenance Rule (a)(4) program based on the active maintenance configurations.

The NRC staffs confirmed that the licensee-provided qualitative risk insights associated with the proposed one-time TS change support the assertion of minimal risk to the plant. The proposed RMAs and compensatory measures further reduce risk and provide adequate defense-in-depth

related to system redundancy, independence, and diversity to maintain safe shutdown capability.

The NRC staff also concluded that the risk insights supported the traditional engineering conclusions associated with the proposed change.

3.3 Risk Insight Evaluation Conclusion Based on the information provided by the licensee and the evaluation above, the NRC staff concludes that the submitted risk insights and RMAs demonstrated minimal risk to CCNPP during the proposed one-time TS change and does not adversely impact safe shutdown capability during a postulated event impacting control room habitability. The NRC staff also concludes that the risk insights are acceptable for the purposes of supporting the deterministic safety evaluation.

4.0 EMERGENCY SITUATION The NRCs regulations in 10 CFR 50.91(a)(5) state that where the NRC finds that an emergency situation exists, in that failure to act in a timely way would result in derating or shutdown of a nuclear power plant, or in prevention of either resumption of operation or of increase in power output up to the plant's licensed power level, it may issue a license amendment involving no significant hazards consideration without prior notice and opportunity for a hearing or for public comment. In such a situation, the NRC will publish a notice of issuance under 10 CFR 2.106, providing for opportunity for a hearing and for public comment after issuance.

As discussed in the licensees application dated March 15, 2025, the licensee requested that the proposed amendment be processed by the NRC on an emergency basis. The licensee stated that CCNPP, Unit 2, is in MODE 5 for a planned refueling outage. Planned outage scope included the E-2 project, which involves extensive upgrades to the electrical distribution system to improve equipment reliability. Unforeseen technical challenges and setbacks in the E-2 Project have resulted in delays restoring the 13.8 kV Service Bus 21. The 13.8 kV Service Bus 21 is required for the 12 CREVS train to be OPERABLE.

The licensee stated that the original schedule for the E-2 Project was developed and challenged in accordance with the licensees outage planning processes. The licensee stated that the original schedule was anticipated to result in restoration of the 13.8 kV Bus 21 and 12 CREVS on March 15, 2025, at 16:00 hours EDT, approximately 3.4 days into the 7-day completion time for TS 3.7.8 Action C.1. On March 9, 2025, at 06:16 hours EDT, CCNPP, Unit 1, entered TS 3.8.1 Condition D for less than 2 off site power supplies available while the 13.8 kV Service Bus 21 was deenergized.

After 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, on March 12, 2025, at 06:16 hours EDT, CCNPP, Unit 1, entered TS 3.7.8 Condition C for one CREVS train inoperable. CCNPP, Unit 1, cannot restore the 12 CREVS train until the 13.8 kV Bus 21 is restored as part of the E-2 Project.

The licensee stated that this one-time extension is necessary to support ongoing maintenance and retesting as part of the E-2 Project. Without an emergency amendment, the licensee would need to shut down CCNP Unit 1.

The NRC staff reviewed the licensees basis for processing the proposed amendment as an emergency amendment (as discussed above) and agrees that an emergency situation exists consistent with the provisions in 10 CFR 50.91(a)(5). Furthermore, the NRC staff determined that:

(1) the licensee used its best efforts to make a timely application; (2) the licensee could not reasonably have avoided the situation; and (3) the licensee has not abused the provisions of 10 CFR 50.91(a)(5). Based on these findings, and the determination that the amendment involves no significant hazards consideration as discussed below, the NRC staff has determined that a valid

need exists for issuance of the license amendment using the emergency provisions of 10 CFR 50.91(a)(5).

5.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION

The NRCs regulation in 10 CFR 50.92(c) states that the NRC may make a final determination, under the procedures in 10 CFR 50.91, that a license amendment involves no significant hazards consideration if operation of the facility, in accordance with the amendment, would not: (1) involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.

An evaluation of the issue of no significant hazards consideration is presented below:

1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

The CREVS is used to mitigate the consequences of an accident. It is designed so that the Control Room remains habitable for operators and to maintain the environment needed for continued equipment operation. The CREVS is not an accident initiator for any previously evaluated accident.

The CREVS is designed to mitigate the consequences of design basis accidents. For that purpose, redundant trains are provided to protect against a single-failure. During the current Technical Specification seven (7) day allowed completion time, an operating unit is allowed by the Technical Specifications to remove one of the CREVS trains from service, thereby eliminating this single-failure protection. The consequences of a design basis accident coincident with a failure of the redundant CREVS train during the extended completion time period are the same as those during the original seven (7) day completion time. Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.

The CREVS is not being modified by this proposed change nor will any unusual operator actions be required. The system will continue to operate in the same manner. The CREVS is not an initiator of any accident but is designed to respond should an accident occur. Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Does the proposed change involve a significant reduction in a margin of safety?

Response: No.

The operability of the CREVS during MODES 1 through 4, and during movement of irradiated fuel, ensures that the Control Room will remain habitable for operators and maintain the environment needed for continued equipment operation under all plant conditions. The proposed change does not affect the function of the CREVS. The extension to allow continued operation with only one train operable is consistent with overall system reliability considerations and provides a limited time to maintain or repair the equipment and conduct testing. The proposed change will allow one train of the CREVS to remain inoperable for up to 17 days, 10 days beyond the current 7-day completion time. The other train of CREVS will have both its normal and emergency power supplies available during this period. The completion time extension does not change any analyses, system operational setpoints, or limited safety system settings required by the accident analyses. Therefore, all existing margins to safety will be maintained as analyzed. Therefore, the proposed change does not involve a significant reduction in a margin of safety.

Based on the above evaluation, the NRC staff concludes that the three standards of 10 CFR 50.92(c) are satisfied. Therefore, the NRC staff has made a final determination that no significant hazards consideration is involved for the proposed amendment and that the amendment should be issued as allowed by the criteria contained in 10 CFR 50.91.

6.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Maryland State official was notified of the proposed issuance of the amendment on March 18, 2025. The State official had no comments.

7.0 ENVIRONMENTAL CONSIDERATION

The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 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 made a final no significant hazards consideration with respect to these amendments. Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments

8.0 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: K. Nguyen, NRR B. Lee, NRR A. Foli, NRR D. Nold, NRR T. Dinh, NRR M. Hamm, NRR Date: March 18, 2025

ML25077A182

• concurrence via email OFFICE NRR/DORL/LPL1/PM NRR/DORL/LPL1/LA NRR/DRA/APLB/BC (A)

NRR/DEX/EEEB/BC NAME SBina KEntz EDavidson WMorton DATE 3/17/2025 3/18/2025 3/18/2025 3/18/2025 OFFICE NRR/DSS/SCPB/BC*

NRR/DSS/STSB/BC OGC -- NLO NRR/DORL/LPL1/BC NAME MValentin SMehta DRoth HGonzález DATE 3/17/2025 3/18/2025 3/18/2025 OFFICE NRR/DORL/LPL1/PM NAME SBina DATE 3/18/2025