ML23228A094

Response to Request for Additional Information for Supplemental License Amendment Request to Revise Technical Specifications and Exemption Request from Requirements of 10CFR50.62 ATWS Rule to Support the .

ML23228A094
Person / Time
Site:	Limerick
Issue date:	08/16/2023
From:	David Helker Constellation Energy Generation
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
Download: ML23228A094 (1)

Text

200 Exelon Way Kennett Square, PA 19348 www.ConstellationEnergy.com 10 CFR 50.90 August 16, 2023 U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 ATTN: Document Control Desk Limerick Generating Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353

Subject:

Response to Request for Additional Information for Supplemental License Amendment Request to Revise Technical Specifications and Exemption Request from Requirements of 10CFR50.62 ATWS Rule to Support the Digital Modernization Project Installation

References:

1. Constellation Energy Generation, LLC (CEG) letter to the U.S. Nuclear Regulatory Commission (NRC), "License Amendment Request to Revise the Licensing and Design Basis to Incorporate the Replacement of Existing Safety-Related Analog Control Systems with a Single Digital Plant Protection System (PPS)," dated September 26, 2022 (NRC Agencywide Documents Access and Management System (ADAMS) Accession No. ML22269A5690).

2. Constellation Energy Generation, LLC letter to U.S. Nuclear Regulatory Commission, License Amendment Request to Revise Technical Specifications and Exemption Request from Requirements of 10CFR50.62 ATWS Rule to Support the Digital Modernization Project Installation, dated February 17, 2023 (ADAMS Accession No. ML23052A022)

3. Email from Nick Smith, U.S. Nuclear Regulatory Commission to Francis Mascitelli, Constellation Energy Generation, LLC, RAIs for Limerick Generation Station, Units 1 and 2 - LAR and Exemption Request for Digital I&C Installation Support (EPID L-2023-LLA-0025 and L-2023-LLE-0005),

dated June 20, 2023 (ADAMS Accession No. ML23173A063)

4. Constellation Energy Generation, LLC letter to U.S. Nuclear Regulatory Commission, Response to Request for Additional Information for Supplemental License Amendment Request to Revise Technical Specifications and Exemption Request from Requirements of 10CFR50.62 ATWS Rule to Support the Digital Modernization Project Installation, dated July 21,2023 (ADAMS Accession ML23202A219).

DMP Installation Support LAR RAI Response Docket Nos. 50-352 and 50-353 August 16, 2023 Page 2

5. Email from Nick Smith, U.S. Nuclear Regulatory Commission to Francis Mascitelli, Constellation Energy Generation, LLC, Additional RAIs for Limerick Generation Station, Units 1 and 2 - LAR and Exemption Request for Digital I&C Installation Support (EPID L-2023-LLA-0025 and L-2023-LLE-0005), dated July 18, 2023 (ADAMS Accession No. ML23201A126)

In accordance with 10 CFR 50.90, Constellation Energy Generation, LLC (CEG) requested a License Amendment Request (LAR) to replace the Limerick Generating Station, Units 1 and 2 existing safety-related analog control systems with a single digital Plant Protection System (PPS) (Reference 1).

In Reference 2, CEG submitted an Installation Support LAR to facilitate the installation of the new PPS described in Reference 1.

In Reference 3, by email dated June 20, 2023, the NRC notified CEG that additional information was needed to complete its review of the Reference 2 submittal.

In Reference 4, CEG responded to the Reference 3 request for additional information (RAI).

In Reference 5, the NRC identified additional RAIs to facilitate their continuing review.

The attachment to this letter provides the response to Reference 5.

CEG has reviewed the information supporting a finding of no significant hazards consideration, and the environmental consideration, which was previously provided to the NRC in the Reference 2 letter. CEG has concluded that the information provided in this RAI response does not affect the bases for concluding that the proposed license amendments do not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92. In addition, CEG has concluded that the information in this supplemental letter does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendments.

This supplemental letter contains no regulatory commitments.

In accordance with 10 CFR 50.91, "Notice for public comment; State consultation,"

paragraph (b), CEG is notifying the Commonwealth of Pennsylvania of this supplemental letter by transmitting a copy of this letter to the designated State Official.

If you have any questions regarding this submittal, then please contact Frank Mascitelli at Francis.Mascitelli@constellation.com or Ashley Rickey at Ashley.Rickey@constellation.com.

DMP Installation Support LAR RAI Response Docket Nos. 50-352 and 50-353 August 16, 2023 Page 3 I declare under penalty of perjury that the foregoing is true and correct. Executed on this 16th day of August 2023.

Respectfully, David P. Helker Sr. Manager - Licensing Constellation Energy Generation, LLC

Attachment:

Response to Request for Additional Information for Supplemental License Amendment Request to Revise Technical Specifications and Exemption Request from Requirements of 10CFR50.62 ATWS Rule to Support the Digital Modernization Project Installation cc: USNRC Region I, Regional Administrator w/ attachment USNRC Project Manager, LGS "

USNRC Senior Resident Inspector, LGS "

Director, Bureau of Radiation Protection - Pennsylvania Department of Environmental Protection "

Attachment License Amendment Request Supplement Limerick Generating Station, Units 1 and 2 Docket Nos. 50-352 and 50-353 Response to Request for Additional Information for Supplemental License Amendment Request to Revise Technical Specifications and Exemption Request from Requirements of 10CFR50.62 ATWS Rule to Support the Digital Modernization Project Installation

DMP Installation Support LAR RAI Response Attachment Docket Nos. 50-352 and 50-353 Page 1 of 10 August 16, 2023 By letter dated February 17, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23052A022), Constellation Energy Generation, LLC (Constellation) submitted to the U.S. Nuclear Regulatory Commission (NRC) a license amendment request (LAR) to revise technical specifications and request an exemption from requirements of Sections 50.62(c)(3), (4) and (5) of Title 10 of the Code of Federal Regulation (10 CFR) to support a digital modernization project installation.

The proposed amendment would revise the technical specifications to adopt features from NUREG-1433, Revision 5, Standard Technical Specifications for General Electric BWR/4 Plants, and revise instrumentation requirements to support the installation of a digital modification during upcoming refueling outages.

The proposed amendment is not a risk-informed amendment submitted in accordance with Regulatory Guide 1.174. Therefore, the NRC staff does not review the licensees probabilistic risk assessment models to determine their technical acceptability. However, the NRC staff considers the licensee-provided qualitative risk insights and associated compensatory measures in its decision on the proposed change.

The NRC staff has determined that additional information is needed to complete its review of the request.

Please provide your responses to these information requests within 30 calendar days.

Requests for Additional Information Regulatory Basis for RAIs 10 and 11 Paragraph 50.62(c)(3) of 10 CFR contains boiling water reactor (BWR) requirements for reduction of risk from anticipated transient without scram (ATWS) events for light water-cooled nuclear power plants regarding the alternate rod insertion (ARI) function.

Paragraph 50.62(c)(4) of 10 CFR contains BWR requirements for reduction of risk from ATWS events for light water cooled nuclear power plants regarding the SLCS function, its automatic capabilities, and specifics related to the concentration of boron in the liquid.

Paragraph 50.62(c)(5) of 10 CFR contains BWR requirements for reduction of risk from ATWS events for light water-cooled reactors regarding the recirculation pump trip function and its automatic capabilities.

DMP Installation Support LAR RAI Response Attachment Docket Nos. 50-352 and 50-353 Page 2 of 10 August 16, 2023

RAI 10

Technical Basis Per Attachment 1, Section 3.5.4, last paragraph, a new time critical manual operator action is created to start the SLCS within 5 minutes upon an ATWS and failed subsequent manual SCRAM attempt. Attachment 1, Section 3.5.5 describe irreversible damage occurring at 6 minutes. The license application does not include the expected ATWS response timing with detailed impacts on the individual ATWS acceptance criteria parameters. This is of even greater significance since ARI will not be available under the conditions proposed by the amendment and local manual actuation of SLCS is the only means of shutting down the reactor in the event of an ATWS.

Information Needed

a. Provide details for the time critical operator action timeline margin with regards to the irreversible damages to acceptance criteria parameters, that is the expected timeline of completion, and by contrast the times of the individual acceptance criteria limits in Attachment 4 being exceeded if the time critical operator action is not performed for vessel pressure, suppression pool temperature, containment pressure, clad temperature, and clad oxidation respectively.

b. Please address the significance of local manual SLCS actuation and any increased effort to maintain the SLCS in a fully operable state during the period of 30 days preceding exit from OPERATIONAL CONDITION 1 at the start of the 2024 refueling outage (Unit 1) and 2025 refueling outage (Unit 2) (i.e., RRCS demotion 30-day period). Provide a full list of compensatory measures, if any, that will be implemented to manage the risk or ensure the availability of SLCS during the RRCS demotion 30-day period.

CEG Response:

a. Validation of the time critical action to manually initiate SLC within 5 minutes of an ATWS event from the Main Control Room (MCR) was performed in accordance with OP-AA-102-106, Operator Response Time Program." A total of ten simulator runs were completed with all crews manually initiating SLC within the allowed time of five minutes (300 seconds). The longest time for any crew to manually initiate SLC from the MCR was 129 seconds, and the average time was 79.5 seconds.

Limerick has contingency procedures if SLC initiation from the MCR fails, but these are not credited for alternative SLC initiation as they cannot be accomplished within 5 minutes.

The 6-minute time duration is used in the PRA as the latest time possible for successful SLC injection initiation to avoid exceeding the EOP Heat Capacity

DMP Installation Support LAR RAI Response Attachment Docket Nos. 50-352 and 50-353 Page 3 of 10 August 16, 2023 Temperature Limit (HCTL). The EOPs direct the operator to depressurize the reactor to 350 psig so HPCI/RCIC can still be used as injection sources.

Controlling the plant conditions below HCTL is a PRA success criterion for ATWS event sequence analysis. It does not represent an irreversible damage state as no containment integrity or fuel integrity challenges would occur for this scenario.

To supplement this PRA information, an independent Limerick control room simulator run was performed at the specific RRCS OOS LAR condition. The results of this simulator run show that HCTL is challenged at 15 minutes with no SLC injection post ATWS.

The 16-minute limit is the actual irreversible damage time used in the PRA as the latest time possible for late SLC actuation to prevent suppression pool temperature from exceeding 260°F. At this suppression pool temperature, primary containment integrity is assumed to be lost per the PRA success criteria.

The 40-minute time duration used in the PRA is not relevant and established as an arbitrary end state in the PRA since the RPV post ATWS can operate indefinitely with RPV power less than the turbine bypass valve capability with the main condenser available as a heat sink.

b. No local manual SLCS actuations are used for the time critical action of manual SLC initiation. Manual initiation of SLC is performed by an operator in the Main Control Room at the Reactor Control panel using existing controls and indications.

SLCS operation after manual initiation from the MCR is verified by the following indications:

• Explosive valve loss of continuity.

• Pump discharge pressure > reactor pressure.

• SLC tank level decreasing.

• Reactor power decreasing.

A full list of compensatory measures, including SLCS related compensatory measures, are included in the response to RAI-15 below.

RAI 11

Technical Basis Per the exemption request in Attachment 7 of the letter dated February 17, 2023, the licensee is seeking exemption from 50.62(c)(3), (4), and (5). In Sections I and II of the exemption request, the licensee is requesting a full exemption from all of the requirements in Sections (3), (4), and (5) of 10 CFR 50.62(c). However, the justification provided by Constellations in the amendment request and exemption request appears to be limited to an exemption from all the requirements in Section (3) of 10 CFR 50.62(c) and exemptions from only the requirements for automatic

DMP Installation Support LAR RAI Response Attachment Docket Nos. 50-352 and 50-353 Page 4 of 10 August 16, 2023 initiation and trip in Sections (4) and (5), respectively.

Information Needed

a. Please clarify whether the exemption for each section of 10 CFR 50.62(c)(3), (4),

and (5) are either full or partial exemption. Specifically, is the exemption request for Sections (4) and (5) of 10 CFR 50.62(c) limited to the requirements for automatic initiation or trip mentioned in those sections.

b. If the exemption request for Sections (4) and (5) of 10 CFR 50.62(c) is not limited to the requirements for automatic initiation or trip mentioned in those sections, please provide (or identify in the LAR and exemption request) the justification, including the special circumstance, for exemption from all the requirements in Sections (4) and (5) of 10 CFR 50.62(c).

CEG Response:

a. For each section of 10 CFR 50.62(c) the following is the type of exemption that is requested:

10 CFR 50.62(c)(3) Full 10 CFR 50.62(c)(4) Partial, limited to the automatic initiation of SLCS.

10 CFR 50.62(c)(5) Partial, limited to the automatic trip of recirculation pump function. The existing safety-related Recirculation Pump Trip system will be substituted with a reliable non-safety related Recirculation Pump Runback (RRB) system.

b. The exemption request for Sections (4) and (5) of 10 CFR 50.62(c) is limited to the requirements for automatic initiation or trip mentioned in those sections; therefore, no additional justification/special circumstances discussion is warranted.

RAI 12

Regulatory Basis Paragraph 50.36(c)(3) of 10 CFR requires that technical specifications document the surveillance requirements for testing, calibration, or inspection of systems to maintain quality of operations.

Technical Basis

1) SR 4.8.1.1.2.h states:

In accordance with the Surveillance Frequency Control Program the diesel

DMP Installation Support LAR RAI Response Attachment Docket Nos. 50-352 and 50-353 Page 5 of 10 August 16, 2023 generator shall be started* and verified to accelerate to synchronous speed in less than or equal to 10 seconds. The generator voltage and frequency shall reach 4160 V and 4400 V and 58.8 Hz and 61.2 Hz within 10 seconds after the start signal. After steady-state conditions are reached, voltage is maintained 4160 V and 4400 V and frequency is maintained 59.8 Hz and 60.8 Hz. The diesel generator shall be started for this test by using one of the following signals:

a) Manual***

b) Simulated loss-of-offsite power by itself.

c) Simulated loss-of-offsite power in conjunction with an ECCS actuation test signal.

d) An ECCS actuation test signal by itself.

The generator shall be manually synchronized to its appropriate emergency bus, loaded to an indicated 2700-2800 KW** and operate for at least 60 minutes. This test, if it is performed so it coincides with the testing required by Surveillance Requirement 4.8.1.1.2.a.4 and 4.8.1.1.2.a.5, may also serve to concurrently meet those requirements as well.

As part of the requested changes related to Technical Specification Task Force (TSTF) Travelers 582 (TSTF-582) and 583-T (TSTF-583-T), the licensee proposes to exclude SR 4.8.1.1.2.h from being required to be performed when shutdown based on saying the test is equivalent to four STS surveillance requirements (SRs) that are not required to be performed during shutdown: specifically, SRs 3.8.1.7, 3.8.1.11, 3.8.1.12 and 3.8.1.19. However, none of these tests require running the generator for greater than 5 minutes, so they are not equivalent to LGS SR 4.8.1.1.2.h which requires the generator to be run for at least 60 minutes. Additionally, as noted in the bold text above, this SR is equivalent to LGS SRs 4.8.1.1.2.a.4 and 4.8.1.1.2.a.5, which, as shown in Table 1, are equivalent to STS SRs 3.8.1.2 and 3.8.1.3. STS SRs 3.8.1.2 and 3.8.1.3 are both required to be performed during shutdown as shown in TSTF 583-T. Therefore, the technical basis for excluding this SR is inconsistent with TSTF-582 and TSTF-583-T.

Information Needed Please provide a revised technical basis for excluding SR 4.8.1.1.2.h from being required during shutdown or revise the LAR to require its performance during shutdown.

CEG Response:

DMP Installation Support LAR RAI Response Attachment Docket Nos. 50-352 and 50-353 Page 6 of 10 August 16, 2023 The justification for removing 4.8.1.1.2.h from performance during OPCON 4 and 5 is revised to address the question:

SR 4.8.1.1.2.h This SR verifies that the DG starts and achieves the required voltage and frequency within 10 seconds based on a manual start, a simulated loss of offsite power, an ECCS actuation test signal, or both a simulated loss of offsite power and an ECCS actuation test signal and operates for at least 60 minutes. There are no accidents evaluated in OPCONs 4 and 5 that assume the DG starts and achieves the required voltage and frequency within 10 seconds, or that the DG starts on a loss of offsite power or ECCS actuation signal. Automatic load shedding and load connection, and DG start and loading on a loss of offsite power is not assumed in OPCONs 4 and 5. While SR 4.8.1.1.2.h encompasses the testing required by 4.8.1.1.2.a.4 and 4.8.1.1.2.a.5, the SRs are not equivalent. Performance of SR 4.8.1.1.2.h can satisfy the acceptance criteria for 4.8.1.1.2.a.4 and 4.8.1.1.2.a.5, but the converse is not true. SR 4.8.1.1.2.a.4 verifies the manual starting of the DG and SR 4.8.1.1.2.a.5 requires demonstration that the DG can be synchronized, gradually loaded, and operate for at least 60 minutes, and these SRs continue to be required to be met in OPCONs 4 and 5. In these OPCONs, an operator can manually start a DG and connect the required loads. The ECCS actuation signal is not required to be operable in OPCONs 4 and 5 (other than Loss of Power, which is discussed below). Therefore, this SR should not be required to be met by SR 4.8.1.2 and the functions that are needed in OPCONS 4 and 5, manual start and loading, and operation for at least 60 minutes, are verified by other SRs that continue to be required. This change will then establish consistency of the LGS SR requirements with the NUREG-1433 STS.

STS and LGS Proposed SRs Applicable in OPCONs 4 and 5:

STS SR Equivalent LGS SR 3.8.1.1 4.8.1.1.1.a 3.8.1.2 4.8.1.1.2.a.4 3.8.1.3 4.8.1.1.2.a.5 3.8.1.4 4.8.1.1.2.a.1 3.8.1.5 4.8.1.1.2.b.1 3.8.1.6 4.8.1.1.2.a.3 3.8.1.9 4.8.1.1.2.e.2 3.8.1.10 4.8.1.1.2.e.3 3.8.1.14 4.8.1.1.2.e.8.a 3.8.1.16 4.8.1.1.2.e.10

DMP Installation Support LAR RAI Response Attachment Docket Nos. 50-352 and 50-353 Page 7 of 10 August 16, 2023

RAI 13

Regulatory Basis Paragraph 50.36(c)(3) of 10 CFR requires that technical specifications document the SRs for testing, calibration, or inspection of systems to maintain quality of operations.

Technical Basis Table 1 in the LAR provides a list of equivalent SRs between LGS and the STS. The table indicates that the equivalent STS SR for LGS SR 4.8.1.1.2.e.12 is STS SR 3.8.1.8. This appears to be a typographical error.

Information Needed Please confirm the correct STS equivalent SR is SR 3.8.1.18 or provide an explanation of how the two SRs (LGS SR 4.8.1.1.2.e.12 and STS SR 3.8.1.8) are equivalent.

CEG Response:

Table 1 is in error. As noted in the question, LGS SR 4.8.1.1.2.e.12 is equivalent to NUREG-1433 SR 3.8.1.18, not SR 3.8.1.8.

RAI 14

Regulatory Basis Paragraph 50.36(c)(2) of 10 CFR states that tech specs shall contain limiting conditions for operation (LCOs). It states that Limiting conditions for operation are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When a limiting condition for operation of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the technical specifications until the condition can be met.

[Emphasis added]

Technical Basis The LAR proposes to revise technical specification 3.9.1, Action b to delete the option of locking the reactor mode switch in the Shutdown mode position. Action b provides the actions to be taken with the one-rod-out interlock inoperable. In this condition, the current technical specification action requires licensee to either: 1) verify that all control rods are fully inserted and disable withdraw capabilities, or 2) lock the reactor mode switch in the Shutdown position. The technical basis for this change stated in the LAR is:

DMP Installation Support LAR RAI Response Attachment Docket Nos. 50-352 and 50-353 Page 8 of 10 August 16, 2023 The purpose of the Functional Unit 11, "Reactor Mode Switch - Shutdown,"

and Functional Unit 12, "Manual Scram," in OPCON 5 is to provide a means for the reactor operator to rapidly insert all control rods into the reactor core.

However, if all control rods are already inserted in all core cells that contain fuel assemblies, this function is not necessary. [Emphasis added]

However, as stated in the Limerick UFSAR, Section 7.2.2.1.2.3.1.17:

Four manual scram push button controls are provided on one control room panel to permit manual initiation of reactor scram at the system level. Failure of an automatic reactor protection system (RPS) function cannot prevent the manual portions of the system from initiating the protective action. The manual scram push buttons are wired as close as is practicable to the scram contactor coil circuits to minimize the dependence of manual scram capability on other equipment. Additional backup to these manual controls is provided by the shutdown position of the reactor system mode switch. [Emphasis added]

Placement of the mode switch in the Shutdown position appears to be an appropriate action in this condition as the necessary action is being taken to ensure all rods are in the core.

Information Needed Provide the basis for eliminating this option as a potential action of operators to take in this condition.

CEG Response:

As discussed in Section 2.2, "Reason for the Proposed Change," the amendment request proposes to adopt requirements from the Standard Technical Specifications (STS) into the LGS TS. The LGS TS 3.9.1, "Reactor Mode Switch," serves the same purpose as STS 3.9.1, "Refueling Equipment Interlocks," which is to prevent inadvertent criticality during refueling by ensuring the refueling equipment interlocks are operable. In some BWR designs, the refueling equipment interlocks are engaged in both the Shutdown and Refuel reactor mode switch positions, and that design was reflected in the standard TS on which the LGS TS are based (i.e., NUREG-0123).

However, in the LGS design, the refueling equipment interlocks are only engaged when the reactor mode switch is in the Refuel position. The STS (i.e., NUREG-1433) changed the old STS (NUREG-0123) to only be applicable when the refueling equipment interlocks are required, which encompasses both designs. The proposed change revises LGS TS 3.9.1 to eliminate references to the Shutdown reactor mode switch position in order to be consistent with the LGS design and the equivalent STS requirements.

DMP Installation Support LAR RAI Response Attachment Docket Nos. 50-352 and 50-353 Page 9 of 10 August 16, 2023 In addition, the revised LCO 3.9.1 requires the reactor mode switch to be locked in the Refuel position. Retaining and using the existing Action b option to lock the reactor mode switch in the Shutdown position would make the LCO not met, and Action a would be applicable. The proposed Action a requires locking the reactor mode switch in the Refuel position. Therefore, retaining the Action b requirement to lock the reactor mode switch in the Shutdown position would be in conflict with the proposed Action a. The proposed changes to LCO 3.9.1, including removing the option to lock the reactor mode switch in the Shutdown position, is consistent with the STS, the LGS design, and the other changes to TS 3.9.1.

Lastly, placing the reactor mode switch in Shutdown does not guarantee that the control rods will be inserted. Whether or not the scram signal would insert the control rods is dependent on the status of the Control Rod Drive system which may not be in operation during portions of a refueling outage. As a result, locking the reactor mode switch in the Shutdown position may not be an adequate remedial action. The proposed ACTION a. requirement to lock the mode switch in Refuel and conduct rod position verification is consistent with STS requirements and sufficient to ensure all rods are inserted and withdraw capabilities are disabled.

RAI 15

Regulatory Basis Per Part 50 of 10 CFR, the NRC will not consider granting an exemption to its regulation unless special circumstances are present. One of the special circumstances in 10 CFR 50.12(a)(2) states, in part, that application of the regulation under particular circumstances is not necessary to achieve the underlying purpose of the rule.

Technical Basis In section II.D of the exemption request, the licensee states:

With the additional compensatory measures being taken, the same level ATWS mitigation protection will be achieved during the 30-day RRCS demolition period when the automatic systems designed to meet compliance with 10 CFR 50.62 ATWS requirements are out of service.

The additional compensatory measures being taken when the automatic systems designed to comply with 10 CFR 50.62 are taken out of service are not explicitly identified in either the exemption request or related LAR as additional compensatory measures. The licensee appears to be relying on these additional compensatory measures as part of its particular circumstances to demonstrate that the automatic functions are not needed to achieve the underlying purpose of the rule during the RRCS demotion 30-day period.

DMP Installation Support LAR RAI Response Attachment Docket Nos. 50-352 and 50-353 Page 10 of 10 August 16, 2023 Information Needed List and describe the additional compensatory measures being taken when the automatic systems designed to comply with 10 CFR 50.62 are taken out of service.

CEG Response:

• From the LAR Section 3.3.5 Risk Insights and referenced Risk Analysis, LG-LAR-031, Risk Assessment Input for the Limerick One-Time Technical Specification Change for the RRCS Pre-Outage Removal, the following Risk Mitigation Actions (RMAs) will be taken:

1. No elective maintenance or testing will be performed on the Reactor Protection System and Control Rod Drive System during the RRCS demolition period. All protected equipment will be managed per procedure OP-AA-108-117, Protected Equipment Program.

2. Operators will brief the unavailability of all RRCS functions removed from service at the beginning of each shift. Operators should discuss alternative procedures and equipment that can be used to perform the functions controlled by RRCS.

3. Operators will brief T-101, RPV Control, and T-117, ATWS RPV Control Flow Chart.

4. All fire risk management actions (RMAs), as required, will be implemented for each configuration per procedure guidance in OP-AA-201-012-1001, Operations On-line Fire Risk Management, Revision 4, and WC-AA-101-1006, On-line Risk Management and Assessment, Revision 4.

• The standby liquid control system (SLCS) beyond design basis ATWS mitigation function is accomplished by pumping an equivalent of 86 gpm of 13 weight percent sodium pentaborate solution (neutron absorbing poison) into the reactor vessel. The Limerick SLC design consists of three 43 gpm capacity independent subsystems, but operation of only two subsystems is required to satisfy 10CFR50.62. The normal system alignment is two independent subsystems aligned for injection with the third independent subsystem out of service in standby. While in the RRCS OOS LCO, if a single SLC subsystem becomes inoperative, the appropriate SLC LCO is entered and the available third out of service independent SLC subsystem can be placed into service to reestablish the required two operable subsystems and exit the SLC LCO. This is the as analyzed SLCS ATWS mitigation configuration while in the RRCS OOS LCO.

• From the LAR- Training references:

Just-in-time training will be conducted before the start of the RRCS demolition for responding to an ATWS condition, and for manual initiation of the SLCS.