AEP-NRC-2023-02, Request for Approval of Change Regarding Neutron Flux Instrumentation

Request for Approval of Change Regarding Neutron Flux Instrumentation

ML23026A284
Person / Time
Site:	Cook
Issue date:	01/26/2023
From:	Ferneau K Indiana Michigan Power Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
AEP-NRC-2023-02
Download: ML23026A284 (1)

Text

Indiana Michigan Power INDIANA Cook Nuclear Plant MICHIGAN One Cook Place POWIR. Bridgman, Ml 49106 indianamichiganpower.com An UP Company 80 UN DL ESS ENE RG y

• January 26, 2023 AEP-NRC-2023-02 10 CFR 50.90 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 REQUEST FOR APPROVAL OF CHANGE REGARDING NEUTRON FLUX INSTRUMENTATION

References:

1. Letter from M. P. Alexich, Indiana & Michigan Electric Company, to Dr. T. E. Murley, U.S. Nuclear Regulatory Commission (NRC), "Additional Information on and Requests for Deviations from Regulatory Guide 1.97, Rev. 3 Recommendations," dated June 29, 1987, Agencywide Documents Access and Management System Accession Number ML173348114.

Pursuant to 10 CFR 50.90, Indiana Michigan Power Company (l&M), the licensee for Donald C. Cook Nuclear Plant (CNP) Unit 1 and Unit 2, is requesting U.S. Nuclear Regulatory Commission (NRC) approval to use alternate means of fulfilling the requirements of Regulatory Guide 1.97 with regards to the plant safety function of reactivity control. l&M is requesting to reclassify the wide range neutron flux instrumentation at CNP Unit 1 and Unit 2 as Category 3 instrumentation, and is requesting a corresponding change to the Technical Specification (TS) for CNP Unit 1 and Unit 2. l&M proposes to modify TS Table 3.3.3-1, Post Accident Monitoring Instrumentation, to remove Function 1, Neutron Flux, from the list of required post-accident monitoring (PAM) instrumentation. The existing TS require two channels of neutron flux instrumentation to be operable.

NRC approval of this proposed change supersedes the commitment made by l&M in Reference 1 to provide environmentally qualified neutron flux instrumentation at CNP Unit 1 and Unit 2.

CNP Unit 2 is currently operating with one neutron flux channel unable to meet its environmental qualification (EQ) requirements, but otherwise fully functional. The inability to meet EQ requirements renders one neutron flux channel at CNP Unit 2 inoperable. The inoperability of the second neutron flux channel at CNP Unit 2 would require the unit to shut down if one channel cannot be restored within seven days.

U.S. Nuclear Regulatory Commission AEP-NRC-2023-02 Page2 The vendor of the wide range neutron flux instruments used at CNP Unit 1 and Unit 2 was not available for emergent support for repair or replacement during the most recent CNP Unit 2 refueling outage and has notified l&M of its intention to discontinue support for these instruments by the end of 2024, with certain spare parts and consumables potentially becoming unavailable prior to that date.

Due to the lead times involved in obtaining replacement parts and vendor support, and that certain portions of the instrumentation cannot be repaired or replaced online, for certain failure modes it is unlikely that a neutron flux channel could be restored to operable status within the required seven day period.

The proposed change to the CNP Unit 1 and Unit 2 TS would remove neutron flux from the list of required PAM instrumentation because other existing instrumentation remains available to control room operators to confirm that the reactor is no longer critical.

The proposed reclassification of wide range neutron flux instrumentation, and associated TS change, would more accurately reflect the use of wide range neutron flux instrumentation as backup instrumentation for the purposes of PAM at CNP Unit 1 and Unit 2 and would allow l&M to pursue resolution of an inoperable neutron flux channel without undue risk of a TS-required shut down. provides an affirmation statement pertaining to the information contained herein. provides a description and assessment of the proposed changes. Enclosure 3 and provide Unit 1 and Unit 2 TS pages, respectively, marked to show the proposed changes. and Enclosure 6 provide Unit 1 and Unit 2 TS Bases pages, respectively, marked to show the proposed changes. TS Bases markups are included for information only. Changes to the existing TS Bases, consistent with the technical and regulatory analysis, will be implemented under TS 5.5.12, "Technical Specifications Bases Control Program."

In accordance with 10 CFR 50.91, a copy of this application, with enclosures, is being provided to the designated Michigan state officials.

l&M requests approval of the proposed TS change commensurate with the NRC's normal review and approval schedule. Once approved, the amendment shall be implemented within 60 days of NRC approval. In the event that a second neutron flux channel becomes inoperable at CNP Unit 2, l&M may request that this proposed TS change be approved on an emergency basis.

U.S. Nuclear Regulatory Commission AEP-NRC-2023-02 Page 3 There are no new commitments in this letter. Should you have any questions, please contact Mr. Michael K. Scarpello, Regulatory Affairs Director, at (269) 466-2649.

Sincerely, Kelly J. Ferneau Site Vice President Indiana Michigan Power Company BMC/sjh

Enclosures:

1. Affirmation

2. Description and Assessment of Changes to Technical Specification Bases

3. Donald C. Cook Nuclear Plant Unit 1 Technical Specification Pages Marked to Show Proposed Changes

4. Donald C. Cook Nuclear Plant Unit 2 Technical Specification Pages Marked to Show Proposed Changes

5. Donald C. Cook Nuclear Plant Unit 1 Technical Specification Bases Pages Marked to Show Proposed Changes

6. Donald C. Cook Nuclear Plant Unit 2 Technical Specification Bases Pages Marked to Show Proposed Ch~nges c: EGLE-RMD/RPS J.B. Giessner- NRC Region Ill M. G. Menze -AEP Ft. Wayne, w/o enclosures 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

Enclosure 1 to AEP-NRC-2023-02 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

~J-~

Kelly J. Ferneau Site Vice President SWORN TO AND SUBSCRIBED BEFORE ME TH1s dV> DAY oF (Ia,auo.r~ 2023

~~~~

My Commission Expires D \\;;)\I ;;}Oas

Enclosure 2 to AEP-NRC-2023-02 Description and Assessment of Changes to Technical Specifications 1.0

SUMMARY

DESCRIPTION Pursuant to 10 CFR 50.90, Indiana Michigan Power Company (l&M), the licensee for Donald C. Cook Nuclear Plant (CNP) Unit 1 and Unit 2, is requesting U.S. Nuclear Regulatory Commission (NRC) approval to use alternate means of fulfilling the requirements of Regulatory Guide (RG) 1.97 with regards to the plant safety function of reactivity control. l&M is requesting to reclassify the wide range neutron flux instrumentation at CNP Unit 1 and Unit 2 as Category 3 instrumentation, and is requesting a corresponding change to the Technical Specification (TS) for CNP Unit 1 and Unit 2.

l&M proposes to modify TS Table 3.3.3-1, Post Accident Monitoring Instrumentation, to remove Function 1, Neutron Flux, from the list of required post-accident monitoring (PAM) instrumentation.

The existing TS require two channels of neutron flux instrumentation to be operable.

NRC approval of this proposed change supersedes the commitment made by l&M in Reference 1 to provide environmentally qualified neutron flux instrumentation at CNP Unit 1 and Unit 2.

CNP Unit 2 is currently operating with one neutron flux channel unable to meet its environmental qualification (EQ) requirements, but otherwise fully functional. The inability to meet EQ requirements renders one neutron flux channel at CNP Unit 2 inoperable. The inoperability of the second neutron flux channel at CNP Unit 2 would require the unit to shut down if one channel cannot be restored within seven days.

The vendor of the wide range neutron flux instruments used at CNP Unit 1 and Unit 2 was not available for emergent support for repair or replacement during the most recent CNP Unit 2 refueling outage and has notified l&M of its intention to discontinue support for these instruments by the end of 2024, with certain spare parts and consumables potentially becoming unavailable prior to that date.

Due to the lead times involved in obtaining replacement parts and vendor support, and that certain portions of the instrumentation cannot be repaired or replaced online, for certain failure modes it is unlikely that a neutron flux channel could be restored to operable status within the required seven day period.

The proposed change to the CNP Unit 1 and Unit 2 TS would remove neutron flux from the list of required PAM instrumentation because other existing instrumentation remains available to control room operators to confirm that the reactor is no longer critical.

The proposed reclassification of wide range neutron flux instrumentation, and associated TS change, would more closely align with the role of the wide range neutron flux instrumentation as backup instrumentation for the purposes of PAM at CNP Unit 1 and Unit 2 and would allow l&M to pursue resolution of an inoperable neutron flux channel without undue risk of a TS-required shut down.

In the event that a second neutron flux channel becomes inoperable at CNP Unit 2, l&M may request that this proposed TS change be approved on an emergency basis.

to AEP-NRC-2023-02 Page 2 2.0 DETAILED DESCRIPTION 2.1 Design and Operation The primary purpose of PAM instrumentation is to display unit variables that provide information required by the control room operators during accident situations. At CNP Unit 1 and Unit 2 neutron flux is currently considered a Type B, Category 1 variable, as described in RG 1.97, Revision 3 (Reference 2), provided to verify reactor shutdown. In a design basis accident, wide range neutron flux instrumentation provides information to control room operators in two situations - to check if the reactor is no longer critical and to monitor the core for unexpected additions of reactivity after reactor shutdown has been achieved.

The initial step of Emergency Operations Procedure (EOP) OHP-4023-E-0 (E-0), Reactor Trip or Safety Injection, directs control room operators to check if the reactor has tripped. During this step, wide range neutron flux instruments are used by control room operators if the expected response is not obtained using other available instrumentation, including reactor trip and bypass breakers, rod bottom lights, and rod position indication.

The Critical Safety Function Status Tree (CSFST) for Subcriticality, OHP-4023-F-0.1 (F-0.1 ), directs control room operators to use wide range neutron flux instruments to monitor for unexpected additions of reactivity after reactor shutdown has been achieved. The wide range neutron flux instruments also perform this role in Function Restoration Procedures OHP-4023-FR-S.1 (FR-S.1 ), Response to Nuclear Power Generation/ATWS, and OHP-4023-FR-S.2 (FR-S.2), Response to Loss of Core Shutdown.

The CNP Unit 1 and Unit 2 TS Bases define the PAM neutron flux channels as nuclear instruments NRl-21 and NRl-23 (also referred to as Gamma-Metrics or Wide Range (WR) Log Power). The detectors are capable of measuring from 10E-8 percent (%) to 200% of reactor power. Both channels can be configured to provide backup source range monitoring during shutdown conditions.

In addition to the installed Gamma-Metrics nuclear instrumentation, CNP Unit 1 and Unit 2 use three sets of Westinghouse neutron detectors with overlapping ranges. The source range, intermediate range, and power range detectors are non-EQ instruments and together are used to monitor the leakage neutron flux from a completely shut down condition to 120% of full power. The power range channels are capable of recording overpower excursions up to 200% of full power.

2.2 Current Technical Specification Requirements Wide range neutron flux instrumentation is used in two sections of the CNP Unit 1 and Unit 2 Technical Specifications, TS 3.3.3, Post Accident Monitoring (PAM) Instrumentation, and TS 3.9.2, Nuclear Instrumentation.

Post Accident Monitoring Instrumentation CNP Unit 1 and Unit 2 TS 3.3.3, Post Accident Monitoring (PAM) Instrumentation, requires two channels of neutron flux instrumentation to be operable while in Modes 1, 2, and 3. If one neutron flux channel becomes inoperable, Required Action A.1 is to restore the required channel to operable status within 30 days. If Required Action A.1 is not met within the associated completion time, a to AEP-NRC-2023-02 Page 3 report shall be submitted to the NRC within 14 days in accordance with TS 5.6.6 Post Accident Monitoring Report.

If two neutron flux channels become inoperable, TS 3.3.3 Post Accident Monitoring (PAM)

Instrumentation, Required Action D.1 is to restore all but one channel to operable status within seven days. If Required Action D.1 is not completed within the associated completion time, Required Action F.1 is to 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 in Mode 4 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

The CNP Unit 1 and Unit 2 TS Surveillance Requirements (SR) associated with PAM instrumentation, SR 3.3.3.1 and SR 3.3.3.3, state:

SR 3.3.3.1 Perform CHANNEL CHECK for each required instrumentation channel that is normally energized.

SR 3.3.3.3 NOTE: Neutron detectors are excluded from CHANNEL CALIBRATION Perform CHANNEL CALIBRATION Nuclear Instrumentation CNP Unit 1 and Unit 2 TS 3.9.2, Nuclear Instrumentation, requires two source range flux monitors to be operable, and one source range audible count rate circuit to be operable while in Mode 6. The associated TS Bases state that the source range flux monitors may be any combination of Westinghouse source range neutron flux monitors and Gamma-Metrics wide range neutron flux monitors.

The CNP Unit 1 and Unit 2 TS Surveillance Requirements associated with Nuclear Instrumentation, SR 3.9.2.1 and SR 3.9.2.2, state:

SR 3.9.2.1 Perform CHANNEL CHECK for each required instrumentation channel that is normally energized.

SR 3.9.2.2 NOTE: Neutron detectors are excluded from CHANNEL CALIBRATION Perform CHANNEL CALIBRATION 2.3 Reason for the Proposed Change During the most recent CNP Unit 2 refueling outage, while performing testing on the TS-required wide range neutron flux instrumentation, small leaks were detected in the jacketing of the cable for 2-NRl-21, Nuclear Instrumentation Channel I Wide Range Radiation Detector. While the jacket breach does not interfere with the ability of 2-NRl-21 to provide reliable indication in a non-adverse containment environment, it does cause 2-NRl-21 to not meet EQ acceptance criteria.

to AEP-NRC-2023-02 Page 4 l&M is actively engaged with the instrument vendor to address the inoperable equipment. The vendor was not available for emergent support for repair or replacement during the most recent CNP Unit 2 refueling outage, and has notified l&M of their intent to discontinue maintenance and support of these instruments at the end of 2024. The vendor also stated that certain spare parts and consumables could become unavailable prior to the end of 2024, due to supplier availability or regulatory restrictions.

Due to the unavailability of the vendor to support emergent repair or replacement of the instrument and its associated cable, the lack of onsite expertise, and the limited spares available, a decision was made to return to power with one TS-required neutron flux channel inoperable, as permitted by TS Limiting Condition for Operation 3.0.4.

In the event that the other wide range neutron flux channel at CNP Unit 2 becomes inoperable, TS 3.3.3, Post Accident Monitoring (PAM) Instrumentation, Required Action 0.1, would require l&M to restore all but one channel to operable status within seven days. Given the situation described above, and the fact that a large portion of the wide range neutron flux channel cannot be repaired or replaced online, for certain failure modes the seven day action statement does not provide sufficient time to restore a neutron flux channel.

Reclassifying the wide range neutron flux instrumentation at CNP Unit 1 and Unit 2 as Category 3 instrumentation, and removing the instrumentation from TS Table 3.3.3-1 would allow l&M to pursue resolution of an inoperable wide range neutron flux instrument without undue risk of a TS-required shutdown. This becomes particularly important as the instrument vendor prepares to end support and maintenance of the currently installed instrumentation.

As Gamma-Metrics neutron flux instruments are installed at several other nuclear plants within the United States, and as availability of spare parts and vendor support for these instruments are coming to an end, l&M proposed to the Nuclear Energy Institute that they consider developing a generic industry response to this situation.

2.4 Description of the Proposed Change l&M proposes to use an alternate means to satisfy the requirements of RG 1.97 with regards to the plant safety function of reactivity control at CNP Unit 1 and Unit 2. l&M proposes that the wide range neutron flux instruments be reclassified as Category 3 instruments, commensurate with their use as backup instruments for post-accident monitoring. l&M also proposes to modify the TS for CNP Unit 1 and Unit 2 TS Table 3.3.3-1, Post Accident Monitoring Instrumentation, to delete Function 1, Neutron Flux.

The proposed reclassification of neutron flux instrumentation to Category 3 would also supersede the regulatory commitment made by l&M in Reference 1 to provide two channels of neutron flux instrumentation that meet Category 1 requirements, including environmental qualification. Two channels of neutron flux instrumentation would remain installed, but Category 1 requirements, including environmental qualification, would no longer be required.

No changes are requested to CNP Unit 1 nor Unit 2 TS 3.9.2, Nuclear Instrumentation.

to AEP-NRC-2023-02 Page 5

3.0 TECHNICAL ANALYSIS

Indications of plant variables are required by the control room operators during accident situations to (1) provide information required to permit the operator to take pre-planned manual actions to accomplish safe shutdown; (2) determine whether the reactor trip, engineered safety feature systems, and manually-initiated safety systems and other systems important to safety are performing their intended functions; and (3) provide information to the operators that will enable them to determine the potential for causing a gross breach of the barriers to radioactivity release and to determine if a gross breach of a barrier has occurred.

In a design basis accident, wide range neutron flux instrumentation provides information to control room operators in two situations - to check if the reactor is no longer critical and to monitor the core for unexpected additions of reactivity after reactor shutdown has been achieved.

Post-Accident Monitoring - Check Reactor Trip EOP E-0, Reactor Trip or Safety Injection, is the entry point for all postulated and analyzed accident conditions, with the single exception of a complete loss of all alternating current electrical power. The Loss of Power scenario does not have an adverse impact on the containment atmosphere, and thus would not challenge the availability of the Gamma-Metrics wide range neutron flux instrumentation.

For events that do not result in a harsh environment in containment (e.g., normal reactor trip, steam generator tube rupture, anticipated transient without SCRAM, etc.), Gamma-Metrics would still be available for use, and would be used as it is normally within the EOP network, regardless of whether the instruments meet EQ acceptance criteria.

When considering events that do result in a harsh environment inside the containment volume, where the neutron flux monitoring equipment may be rendered inoperable, the timing of EOP E-0 Step 1, Check Reactor Trip, in relation to the event should be considered.

The first four steps of EOP E-0, including Check Reactor Trip, are Immediate Actions, and are performed by control room operators from memory. Performance of the Immediate Actions is not a timed evolution per the Time Critical Operator Actions (TCOA) program. The shortest defined TCOA is timed from the reactor trip until auxiliary feedwater is isolated, which occurs at Step 8 of E-0. The required time for this action is six minutes, and validation of the actions have shown that the action has historically occurred between four and five minutes. This timing includes the Immediate Actions and a subsequent review of each of those actions by the unit supervisor using the hard copy of the procedure. As such, a one minute expectation for completion of the first immediate action step is reasonable and conservative.

Within the first minute of an accident involving release of energy into containment (High Energy Line Break or Loss of Coolant Accident), it is expected that the nuclear instruments that monitor reactor power would not yet be adversely impacted by the degrading conditions within the containment volume. This is borne out by the structure of E-0 Step 1, which allows the operators to use all available nuclear instruments (Westinghouse and Gamma-Metrics) to perform the 'Action/Expected Response' to AEP-NRC-2023-02 Page6 (AER, left hand column) actions to verify that 'Neutron Flux is lowering'. This is further described in the basis section for Step 1 in the Plant Specific Background Document for E-0:

"When checking "Neutron flux - LOWERING" in the AER, It is acceptable for the operator to check either the Westinghouse Power Range indications or the Gamma Metrics WR Log Power indicators since a diverse group of parameters is used to check the reactor tripped.

(i.e. reactor trip and bypass breaker positions, rod bottom lights, rod position indication, and neutron flux trend)"

Therefore, the operators will use any operable wide range neutron flux instrument to perform the immediate actions of E-0 at the beginning of an event if the containment conditions are harsh, and the environmental qualification, or lack thereof, of the Gamma-Metrics instruments is not expected to impact their ability to provide information to control room operators during the initial steps of the E-0 procedure.

Post-Accident Monitoring - Critical Safety Function: Subcriticality The CSFST for Subcriticality, F-0.1, directs control room operators to use wide range neutron flux instruments to monitor for unexpected additions of reactivity after reactor shutdown has been achieved. In the event of a loss of shutdown condition, F-0.1 directs control room operators to one of the two associated function restoration procedures, FR-S.1 or FR-S.2.

During an accident that involves normal containment conditions, the neutron flux monitoring instrumentation is expected to be available for use. Under these conditions, control room operators are able to monitor the reactivity state of the core by evaluating neutron flux behavior measured by all of the neutron flux monitoring instrumentation (Gamma-Metrics in addition to Westinghouse power range, intermediate range, and source range Westinghouse instruments) as well as Core Exit Thermocouple (CET) temperatures, Reactor Coolant System (RCS) hot leg and cold leg temperatures, and boron concentration.

However, during an accident that involves adverse containment conditions, where the neutron flux monitoring equipment may be rendered inoperable, control room operators would still be able to monitor core and RCS temperature behavior by CETs, RCS hot leg temperatures and RCS cold leg temperatures. Additionally, the shutdown margin would be verified by measuring boron concentration.

The EOPs would also direct the operators to assure that boric acid injection is taking place, adding negative reactivity to ensure that the core remains shut down.

While temperature and boron concentration are not direct measurements of neutron flux, it is important to consider that the CSFSTs are only intended to determine if an imminent threat to a critical safety function exists. The CSFSTs act as a decision point in order to determine if the operator should immediately suspend the performance of optimum recovery procedures in order to address this challenge. A continuous challenge does not exist unless the core is producing enough power that a temperature rise is indicated on the RCS temperature instruments.

In addition, neutron flux instrumentation is not always proportional to reactor power, and therefore may provide anomalous indications which can potentially mislead the operator. Excore neutron flux instrumentation response is dependent on the location of voiding in the core and/or downcomer, the degree of core uncovery, and detector location. This is particularly likely for accidents which produce to AEP-NRC-2023-02 Page 7 harsh containment environments, since reactor vessel voiding may be occurring. Anomalous neutron flux in~ication (i.e., indication not proportional to reactor power) was observed at the Three Mile Island accident (Reference 3) and has been demonstrated in NRC financed experiments (Reference 4). In the event of large uncontrolled and potentially unknown variations in core flow and heat removal rate, the proposed temperature indication can be considered just as reliable as the established neutron flux instrumentation with regards to providing control room operators with relevant and meaningful information.

While l&M is confident that existing EOPs are adequate to address any design basis accident or transient at CNP Unit 1 or Unit 2, given the information discussed above, and given that CNP Unit 2 currently has one wide range neutron flux channel that does not meet EQ requirements, an internal training request has been generated for refresher training for licensed operators to discuss the various other indications that can be used in the absence of both channels of wide range nuclear instrumentation.

l&M is also revising the background documentation for E-0 and FR-S.1 to discuss the need to use additional indications for verification of reactor status in the event that both trains of Gamma-Metrics become unavailable. In addition, a new sub-step is being added to FR-S.1 Step 19, Check Reactor Subcritical, to direct control room operators to perform this additional evaluation of reactor status.

This procedure change will allow a transition out of FR-S.1 that may otherwise not be available to control room operators in the event that both trains of Gamma-Metrics become unavailable. Operators will be trained on these enhancements prior to making the EOP changes effective.

4.0 REGULATORY ASSESSMENT 4.1 Applicable Regulatory Requirements/Criteria The proposed change has been evaluated to determine whether applicable regulations and requirements continue to be met.

RG 1.97, Revision 3 (Reference 2), describes five types of variables for the purpose of aiding in selecting accident-monitoring instrumentation and applicable criteria, Type A, B, C, D, and E. Neutron Flux is a Type B variable associated with the plant safety function of reactivity control. Type B variables are those variables that provide information to indicate whether plant safety functions are being accomplished.

Design and qualification criteria for post-accident monitoring instrumentation are also delineated in RG 1.97, Revision 3. The criteria are separated into three separate groups or categories that provide a graded approach to requirements depending on the importance to safety of the measurement of a specific variable. The two categories relevant to this amendment request are Category 1 and Category 3. Category 1 provides the most stringent requirements and is intended for key variables.

Category 3 provides less stringent requirements and generally applies to backup and diagnostic instrumentation.

RG 1.97, Revision 3, established Neutron Flux as a Type B, Category 1 variable with regards to the plant safety function of reactivity control, provided for the purposes of function detection, and accomplishment of mitigation.

Enclosure 2 to AEP-NRC-2023-02 Page 8 Neutron flux monitoring equipment at CNP Unit 1 and Unit 2 is expected to be available during an accident that involves normal containment conditions, and will be used by control room operators to monitor subcriticality in these scenarios. CNP Unit 1 and Unit 2 EOPs also require control room operators to monitor RCS temperature using CETs and RCS hot leg and cold leg instruments, and to monitor boron concentration and the assurance of boron injection. As such, in the event of an accident that renders neutron flux instrumentation inoperable, sufficient instrumentation remains available to control room operators to ensure an imminent threat to the critical safety function of subcriticality is not present.

l&M proposes an alternative method of fulfilling the requirements of RG 1.97 with regards to reactivity control. It is proposed that RCS Hot Leg Water Temperature, RCS Cold Leg Temperature, and Core Exit Temperature be considered as Type B variables for reactivity control, for the purpose of function detection, and that the associated instrumentation meet the requirements of Category 1 instrumentation. Neutron flux would be considered as backup instrumentation for the purpose of verification of reactivity control, and a Category 3 classification is appropriate.

Section 1.4 of the CNP Updated Final Safety Analysis Report contains a set of plant specific design criteria (PSDC) that define the principal criteria and safety objectives for the design of CNP Unit 1 and Unit 2. PSDC 13, Fission Process Monitors and Controls, states that means shall be provided for monitoring or otherwise measuring and maintaining control over the fission process throughout core life under all conditions that can reasonably be anticipated to cause variations in reactivity of the core. As discussed in Section 3.0 of this Enclosure, the Gamma-Metrics wide range neutron flux instruments are expected to be available during any event that does not result in an adverse containment environment, and in the event that an adverse containment environment exists which causes the Gamma-Metrics neutron flux instruments to become unavailable, RCS Hot Leg and Cold Leg temperature instruments, in addition to CETs, would continue to provide information to control room operators consistent with the requirements of PSDC 13.

In the Code of Federal Regulations, 10 CFR 50.34(f)(2)(xix) requires licensees of nuclear plants to provide instrumentation adequate for monitoring plant conditions following an accident that includes core damage. As discussed above in Section 3.0 of this Enclosure, in the event that an adverse containment environment exists which causes the Gamma-Metrics neutron flux instruments to become unavailable, the RCS temperature instrumentation, including hot leg, cold leg, and CETs, would continue to provide information to control room operators regarding reactor core and RCS temperature behavior. Thus, the requirements in 10 CFR 50.34(f)(2)(xix) continue to be met.

10 CFR 50.49, Environmental qualification of electric equipment important to safety for nuclear power plants, requires licensee of nuclear plants to establish a program for qualifying certain electrical equipment important to safety, including environmental qualification. The equipment covered by this section includes safety-related equipment that is relied upon to remain functional during and following design basis events to ensure (1) the integrity of the reactor coolant pressure boundary, (2) the capability to shut down the reactor and maintain it in a safe shutdown condition, or (3) the capability to prevent or mitigate the consequences of accidents that could result in potential offsite radiation exposures. Also covered by this section is certain post-accident monitoring equipment, per guidance provided in Revision 2 of RG 1.97. As discussed above, neutron flux would be considered as backup instrumentation for the purpose of verification of reactivity control, and while control room operators would continue to use the information provided by the Gamma-Metrics instruments as long as it is available, the instruments themselves would not be relied upon in the event of an adverse to AEP-NRC-2023-02 Page 9 containment environment. Thus, with neutron flux considered as backup instrumentation, the requirements of 10 CFR 50.49 would not dictate that neutron flux instrumentation be environmentally qualified.

10 CFR 50.36(c)(2)(ii) provides four criteria that would necessitate establishing a TS limiting condition for operation. When considering neutron flux as a Category 3 variable, consistent with its use as backup instrumentation for PAM at CNP Unit 1 and Unit 2, none of the four criteria apply, and removal from TS Table 3.3.3-1, Post Accident Monitoring Instrumentation, is justified.

Based on the considerations above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will continue to be conducted in accordance with the site licensing basis, and (3) the approval of the proposed change will not be inimical to the common defense and security or to the health and safety of the public.

In conclusion, CNP has determined that the proposed change does not require any exemptions or relief from regulatory requirements and does not affect conformance with any regulatory requirements/criteria.

4.2 No Significant Hazards Consideration Pursuant to 10 CFR 50.90, Indiana Michigan Power Company (l&M), the licensee for Donald C. Cook Nuclear Plant (CNP) Unit 1 and Unit 2, is requesting U.S. Nuclear Regulatory Commission (NRC) approval to use alternate means of fulfilling the requirements of Regulatory Guide 1.97 with regards to the plant safety function of reactivity control. l&M is requesting to reclassify the wide range neutron flux instrumentation at CNP Unit 1 and Unit 2 as Category 3 instrumentation, and is requesting a corresponding change to the Technical Specification (TS) for CNP Unit 1 and Unit 2. l&M proposes to modify TS Table 3.3.3-1, Post Accident Monitoring Instrumentation, to remove Function 1, Neutron Flux, from the list of required post-accident monitoring (PAM) instrumentation. The existing TS require two channels of neutron flux instrumentation to be operable.

l&M has evaluated whether or not a significant hazards consideration is involved with the proposed TS Bases change by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below:

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

Response: No.

The proposed TS change involves changes to the specific set of instruments that are considered to be required PAM instrumentation. The proposed change does not involve a physical change to the plant or a change in the manner in which the plant is operated or controlled. The PAM instrumentation provides information to control room operators after an accident has occurred. Therefore, the probability of occurrence of an accident previously evaluated is not significantly increased by the proposed amendment.

to AEP-NRC-2023-02 Page 10 The proposed change modifies which instruments are considered necessary for PAM, but ensures that the information required by control room operators is still available in the event of an accident, thus not significantly increasing the consequences of an accident previously evaluated.

Therefore, it is concluded that the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

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

Response: No.

The proposed TS change involves changes to the specific set of instruments that are considered to be required PAM instrumentation and does not alter the design function or operation of any structure, system, or component that may be involved in the initiation of an accident. The proposed change does not create new failure mechanisms, malfunctions, or accident initiators. The proposed change does not involve a physical change to the plant (i.e., no new or different type of equipment will be installed) or a change to the manner in which the plant is operated or controlled. Therefore, the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

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

Response: No.

The proposed TS change involves changes to which instrumentation is required to be operable for post-accident monitoring. This change does not alter the manner in which safety limits, limiting safety system setpoints, or limiting conditions for operation are determined. The specific set of instruments that are considered to be required PAM instrumentation are changed, but the necessary information available to control room operators is retained. Therefore, the proposed change does not involve a significant reduction in a margin of safety.

In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the NRC's regulations, and (3) approval of the proposed TS change will not be inimical to the common defense and security or to the health and safety of the public. l&M concludes that the proposed TS change presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c) and, accordingly, a finding of "no significant hazards consideration" is justified.

4.3 Environmental Consideration A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed TS change does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed TS change to AEP-NRC-2023-02 Page 11 meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b ), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

5.0 PRECEDENT In November of 1995, the NRC issued a Supplemental Safety Evaluation (Reference 5) to Rochester Gas and Electric Corporation, regarding Conformance to RG 1.97, Revision 2, concluding that the existing post-accident neutron flux monitoring instrumentation at the R.E. Ginna Nuclear Power Plant, is acceptable with respect to RG 1.97, Revision 2, on the basis of appropriate EQ alternate instrumentation and boron injection capability as directed in the plant EOPs. The Subsequent Safety Evaluation stated that, during an accident that involves adverse containment conditions, where the neutron flux monitoring instrumentation may be rendered inoperable, the operator would monitor core and RCS temperature behavior by core exit temperature, RCS hot leg temperature, and RCS cold leg temperature instrumentation.

Equivalent Supplemental Safety Evaluations were also sent out in November of 1995, to Consolidated Edison Company (Reference 6), and Duquesne Light Company (Reference 7), regarding Indian Point Nuclear Generating Station, Unit 2, and Beaver Valley Power Station, Unit 1,. respectively.

6.0 REFERENCES

1. Letter from M. P. Alexich, Indiana & Michigan Electric Company, to Dr. T. E. Murley, U.S.

Nuclear Regulatory Commission (NRC), "Additional Information on and Requests for Deviations from Regulatory Guide 1.97, Rev. 3 Recommendations," dated June 29, 1987, (ADAMS Accession Number ML173348114).

2. Regulatory Guide 1.97, "Instrumentation for Light-Water-Cooled Nuclear Power Plants to Assess Plant and Environs Conditions During and Following an Accident," Revision 3, May 1983 (ADAMS Accession Number ML003740282).

3. NSAC-1, "Supplement to Analysis of Three Mile Island - Unit 2 Accident," Electric Power Research Institute (Nuclear Safety Analysis Center), July 1979.

4. The Response of Ex-Core Neutron Detectors to Large- and Small-Break Loss-of-Coolant Accidents in Pressurized Water Reactors, E. Wilson Okyere, Anthony J. Baratta, and William A. Jester, Nuclear Technology, Vol. 96, December 1991.

5. Letter from A. R. Johnson, U.S. NRC to Dr. R.C. Mecredy, Rochester Gas and Electric Corporation, "Conformance to Regulatory Guide 1.97, Revision 2, Post-Accident Neutron Flux Monitoring Instrumentation (TAC No. M90036)," November 27, 1995.

6. Letter from F.J. Williams, Jr., U.S. NRC to S.E. Quinn, Consolidated Edison Company, "Conformance to Regulatory Guide 1.97, Revision 2, Post-Accident Neutron Flux Monitoring Instrumentation for Indian Point Nuclear Generating Unit No. 2 (TAC No. M81727),"

November 27, 1995.

7. Letter from D.S. Brinkman, U.S. NRC to J.E. Cross, Duquesne Light Company, "Conformance to Regulatory Guide 1.97, Revision 2, Post-Accident Neutron Flux Monitoring Instrumentation for Beaver Valley Power Station, Unit No. 1 (TAC No. M81201)," November 17, 1995.

Enclosure 3 to AEP-NRC-2023-02 Donald C. Cook Nuclear Plant Unit 1 Technical Specification Pages Marked to Show Proposed Changes

PAM Instrumentation 3.3.3 Table 3.3.3-1 (page 1 of2)

Post Accident Monitoring Instrumentation CONDITION REFERENCED FROM REQUIRED FUNCTION REQUIRED CHANNELS ACTION E.1

1. Ne1:1tF8A Fl1:1l< !Deletec:11 i F-

2. Steam Generator Pressure (per steam generator) 2 F

3. Reactor Coolant System (RCS) Hot Leg 2 F Temperature (Wide Range) -

4. RCS Cold Leg Temperature (Wide Range) 2 F

5. RCS Pressure (Wide Range) 2 F

6. Reactor Coolant Inventory Tracking System 2 G (Reactor Vessel Level Indication)

7. Containment Water Level 2(a) F

8. Containment Pressure (Narrow Range) 2 F

9. Penetration Flow Path Containment Isolation Valve 2 per penetration flow F Position path(b)(c)

10. Containment Area Radiation (High Range) 2 G

~

11. Deleted

12. Pressurizer Level 2 F

13. Steam Generator Water Level (Wide Range) 4 F

14. Condensate Storage Tank Level 1 G

15. Core Exit Temperature - Quadrant 1 2(d) F

16. Core Exit Temperature - Quadrant 2 2(d) F

17. Core Exit Temperature - Quadrant 3 2(d) F

18. Core Exit Temperature - Quadrant 4 2(d) F (a) Up to one channel of Function 7 OPERABILITY requirements can be satisfied by an OPERABLE train of containment water level switches if both Containment Water Level channels are inoperable. 'fhis substitution is only allowed until the end of the current operating cycle when it is invoked.

(b) Not required for isolation valves whose associated penetration is isolated by at least one closed and deactivated automatic valve, closed manual valve, blind flange, or check valve with flow through the valve secured.

(c) Only one position indication channel is required for penetration flow paths with only one installed control room indication channel.

(d) A channel consists of one core exit thermocouple (CET).

Cook Nuclear Plant Unit 1 3.3.3-4 Amendment No. 287, ~ . 3eQ

==;==---------~_,;;;;;;;;;;~;;;;;;;;;

;..-._ ___,;;;;;;;;;;;~;....,_-

Enclosure 4 to AEP-NRC-2023-02 Donald C. Cook Nuclear Plant Unit 2 Technical Specification Pages Marked to Show Proposed Changes

PAM Instrumentation 3.3.3 Table 3.3.3-1 (page 1 of 2)

Post Accident Monitoring Instrumentation CONDITION REFERENCED FROM REQUIRED FUNCTION REQUIRED CHANNELS ACTION E.1

1. Ne1a1tFOA FIYlE Deleted! ~ ~

2. Steam Generator Pressure (per steam generator) 2 F

3. Reactor Coolant System (RCS) Hot Leg 2 F Temperature (Wide Range)

4. RCS Cold Leg Temperature (Wide Range) 2 F

5. RCS Pressure (Wide Range) 2 F

6. Reactor Coolant Inventory Tracking System 2 G (Reactor Vessel Level Indication)

7. Containment Water Level 2<a) F

8. Containment Pressure (Narrow Range) 2 F

9. Penetration Flow Path Containment Isolation Valve 2 per penetration flow F Position path(b)(c)

10. Containment Area Radiation (High Range) 2 G

11. Deleted

12. Pressurizer Level 2 F

13. Steam Generator Water Level (Wide Range) 4 F

14. Condensate Storage Tank Level 1 G

15. Core Exit Temperature - Quadrant 1 2(d) F

16. Core Exit Temperature - Quadrant 2 2(d) F

17. Core Exit Temperature - Quadrant 3 2(d) F

18. Core Exit Temperature - Quadrant 4 2(d) F (a) Up to one channel of Function 7 OPERABILITY requirements can be satisfied by an OPERABLE train of containment water level switches if both Containment Water Level channels are inoperable. This substitution is only allowed until the end of the current operating cycle when it is invoked.

(b) Not required for isolation valves whose associated penetration is isolated by at least one closed and deactivated automatic valve, closed manual valve, blind flange, or check valve with flow through the valve secured .

(c) Only one position indication channel is required for penetration flow paths with only one installed control room indication channel.

(d) A channel consists of one core exit thermocouple (CET).

Cook Nuclear Plant Unit 2 3.3.3-4 Amendment No. 299, 299, 342

Enclosure 5 to AEP-NRC-2023-02 Donald C. Cook Nuclear Plant Unit 1 Technical Specification Bases Pages Marked to Show Proposed Changes

PAM Instrumentation B 3.3.3 BASES LCO (continued)

One exception to the two channel requirement is Containment Isolation Valve (CIV) Position. In this case, the important information is the status of the containment penetrations. The LCO requires one position indicator for each active CIV. This is sufficient to redundantly verify the isolation status of each isolable penetration either via indicated status of the active valve and prior knowledge of a passive valve, or via system boundary status. If a normally active CIV is known to be closed and deactivated, position indication is not needed to determine status. Therefore, the position indication for valves in this state is not required to be OPERABLE.

Type A and Category 1 variables meet Regulatory Guide 1.97 Category 1 (Ref. 3) design and qualification requirements for seismic and environmental qualification, single failure criterion, utilization of emergency standby power, immediately accessible display, continuous readout, and recording of display, except for approved deviations, as described in References 1 and 2.

Listed below are discussions of the specified instrument Functions listed in Table 3.3.3-1. For all applicable Functions, the recorder or indicator may be used as the qualified instrument.

1. Neutron Flux !Deleted!

Neutron Flux (NRI 21 ana NRI 23) is a Category 1 ¥ariable pro¥iaea to ¥erify reactor shutaown. The range of eash of the two neutron flux instruments (1 OE 8 to 200% power) 00 1,ers the full range of flux that may ossur post assiaent.

2. Steam Generator (SG) Pressure (per SG)

Steam Generator Pressure is a Type A, Category 1 variable provided for determination of required core exit temperature. Three steam generator pressure channels per steam generator are provided (MPP-210, MPP-211, MPP-212, MPP-220, MPP-221, MPP-222, MPP-230, MPP-231, MPP-232, MPP-240, MPP-241, and MPP-242).

Each channel has a range of O psig to 1200 psig. However, only two steam generator pressure channels per steam generator are required to satisfy the guidance in Reference 3. Each steam generator is treated separately and each steam generator is considered a separate Function. Therefore, separate Condition entry is allowed for each steam generator. This is acceptable since each steam generator has two channels and the channels of one steam generator are independent from the channels of the other steam generators.

Cook Nuclear Plant Unit 1 B 3.3.3-3 Revision No. 44

Enclosure 6 to AEP-NRC-2023-02 Donald C. Cook Nuclear Plant Unit 2 Technical Specification Bases Pages Marked to Show Proposed Changes

PAM Instrumentation B 3.3.3 BASES LCO (continued)

One exception to the two channel requirement is Containment Isolation Valve (CIV) Position. In this case, the important information is the status of the containment penetrations. The LCO requires one position indicator for each active CIV. This is sufficient to redundantly verify the isolation status of each isolable penetration either via indicated status of the active valve and prior knowledge of a passive valve, or via system boundary status. If a normally active CIV is known to be closed and deactivated, position indication is not needed to determine status. Therefore, the position indication for valves in this state is not required to be OPERABLE.

Type A and Category 1 variables meet Regulatory Guide 1.97 Category 1 (Ref. 3) design and qualification requirements for seismic and environmental qualification, single failure criterion, utilization of emergency standby power, immediately accessible display, continuous readout, and recording of display, except for approved deviations, as described in References 1 and 2.

Listed below are discussions of the specified instrument Functions listed in Table 3.3.3-1. For all applicable Functions, the recorder or indicator may be used as the qualified instrument.

1. Neutron Flw< !Deleted!

Neutron Flu:>< (NRI 21 and NRI 23) is a Category 1 ¥ariable 13ra¥ided ta ¥erify reaotar shutdown. The range af each af the t\\la neutran flu:><

instruments (1 OE 8 ta 200% 13awer) ca1.iers the full range af flu:>< that may accur past accident.

2. Steam Generator (SG) Pressure (per SG)

Steam Generator Pressure is a Type A, Category 1 variable provided for determination of required core exit temperature. Three steam generator pressure channels per steam generator are provided (MPP-210, MPP-211, MPP-212, MPP-220, MPP-221, MPP-222, MPP-230, MPP-231, MPP-232, MPP-240, MPP-241, and MPP-242).

Each channel has a range of O psig to 1200 psig. However, only two steam generator pressure channels per steam generator are required to satisfy the guidance in Reference 3. Each steam generator is treated separately and each steam generator is considered a separate Function. Therefore, separate Condition entry is allowed for each steam generator. This is acceptable since each steam generator has two channels and the channels of one steam generator are independent from the channels of the other steam generators.

Cook Nuclear Plant Unit 2 B 3.3.3-3 Revision No. 44