ML26003A002

(1/1/2026) Email from C.Ludwig to R.Guzman Draft Notice of Enforcement Discretion Request

ML26003A002
Person / Time
Site:	Millstone
Issue date:	01/01/2026
From:	Ludwig C Dominion Energy Nuclear Connecticut
To:	Richard Guzman NRC/NRR/DORL/LPL1
References
EPID L-2026-LLD-0000
Download: ML26003A002 (0)

Text

From:

Cailyn.B.Ludwig@dominionenergy.com To:

Rich Guzman Cc:

Daniel.C.Beachy@dominionenergy.com; ext_Shayan_Sinha

Subject:

[External_Sender] M3 NOED for TS 3.7.1.2 Date:

Thursday, January 1, 2026 5:34:53 PM Attachments:

26-001 - M3 TT NOED Final FSRC Approved.pdf

Hello, See attached for the Millstone 3 draft NOED for TS 3.7.1.2. As we discussed, I will let you know by 0700 if we will require a meeting.

Thank you!

Cailyn Cailyn Ludwig Nuclear Fleet Licensing W: 804.273.5131

Serial No.26-001 Docket No. 50-423 Attachment, Page 1 of 14 Request for Enforcement Discretion from the Shutdown Requirement of Technical Specification 3.7.1.2 Auxiliary Feedwater System Introduction Dominion Energy Nuclear Connecticut, Inc. (DENC) hereby requests the Nuclear Regulatory Commission (NRC) staff to exercise discretion not to enforce compliance with the Millstone Power Station Unit 3 (MPS3) Technical Specification (TS) 3.7.1.2, Auxiliary Feedwater System, Action c.

Discussion of the Requirements for which Enforcement Discretion is Requested Consistent with NRC Enforcement Manual, Appendix F, Notices of Enforcement Discretion, DENC herein provides a supporting description and justification for issuance of the requested Notice of Enforcement Discretion (NOED). DENC is requesting a NOED to avoid an unnecessary shutdown of the MPS3 reactor without a corresponding health and safety benefit.

REQUIRED INFORMATION

1.

Explain why a licensing process is not appropriate to address the issue and why the need for a NOED could not reasonably been avoided. If applicable, this explanation shall address previous instances of the issue and decisions to pursue licensing solutions in the past.

During performance of SP 3622.3-001, TDAFW Pump Operational Readiness and Quarterly IST Group B Pump Tests, for Turbine Driven Auxiliary Feedwater (TDAFW)

Pump (3FWA*P2), the acceptance criteria of TDAFW pump establishing 1650 psid discharge pressure within 90 seconds of signal actuation was not met. The 90-second start time is based on thermal-hydraulic calculations in the MPS3 Final Safety Analysis Report (FSAR) Chapter 15 that identify this time as the duration that steam generator inventory can sustain decay heat removal without feedwater. Chapter 7 ensures the control logic meets this assumption. The 72-hour shutdown action statement for TS 3.7.1.2 expires on January 2, 2026 at 12:35 hours.

This condition results in the TDAFW pump being inoperable, which puts the unit into a 72-hour allowed outage time (AOT). This NOED request is being made for an extension period of 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> to remain in POWER OPERATION (MODE 1) rather than progressing to HOT STANDBY (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 HOT SHUTDOWN (MODE 4) within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> as required by Action c for TS 3.7.1.2. The requested extension will allow time for DENC to make the necessary repairs to 3FWA*P2 and perform post-maintenance testing (PMT), which will restore the associated auxiliary feedwater pump to operable status.

Serial No.26-001 Docket No. 50-423 Attachment, Page 2 of 14 Consequently, DENC reviewed NRC Enforcement Manual, Appendix F, Notices of Enforcement Discretion and determined that this request satisfies Section 1.3 -

Applicability, as the time to process an Exigent or Emergency License Amendment Request (LAR) is not feasible due to the 72-hour Allowed Outage Time (AOT) of the Technical Specification Action Statement (TSAS). After the failure was identified, work proceeded on a 24/7 basis with the goal of completing repairs and validating operation of the pump prior to expiration of the AOT. The criterion of the Enforcement Manual Appendix for Notice of Enforcement Discretion applies to situations where compliance with the TS would result in a potentially unnecessary down-power or the shutdown of a reactor without a corresponding health and safety benefit. Initially, DENC did not believe enforcement discretion would be needed since the planned troubleshooting, corrective maintenance, and restoration of Operability was expected to be completed within the original AOT. However, as corrective maintenance planning progressed, completion of corrective maintenance and required post maintenance testing was forecasted to extend beyond the original 72-hour AOT. Thus, enforcement discretion is needed.

A follow-up emergency TS change LAR is not required because the affected system will be restored to operable status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after the existing TS 3.7.1.2 Action c AOT.

A similar issue occurred in 2023, where the turbine-driven auxiliary feedwater pump governor failed to meet the 90-second acceptance criteria, taking 187 seconds to reach 1650 PSIG. The root cause was attributed to internal governor discrepancies, specifically corrosion on the shutdown solenoid plunger and a stack-up misalignment of speed-setting components, rather than linkage or external components. That event was resolved by reinstalling the previous governor and did not require a licensing solution because operability was restored promptly after corrective maintenance. Since then, multiple successful quarterly tests (with margin to the 90-second criteria) have been performed, demonstrating reliable operation until the current occurrence. This history supports that the present issue could not have been reasonably foreseen and explains why a NOED is being pursued.

Based on the above, the criteria for enforcement discretion are satisfied.

2.

Provide a description of the TSs or other license conditions that will be violated. This description shall include the time the condition was entered and when the completion time will expire.

DENC is requesting enforcement discretion from the TS 3.7.1.2, Action c allowed outage time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> as stated above. TS 3.7.1.2 describes the LCO for the auxiliary feedwater system. The LCO requires that in Modes 1, 2, and 3, at least three independent steam generator auxiliary feedwater pumps and associated flow paths shall be OPERABLE with:

a. Two motor-driven auxiliary feedwater pumps, each capable of being powered from separate emergency busses, and b. One steam turbine-driven auxiliary feedwater pump capable of being powered from an OPERABLE steam supply system. Action c requires

Serial No.26-001 Docket No. 50-423 Attachment, Page 3 of 14 that with one auxiliary feedwater pump inoperable, the unit must restore the required auxiliary feedwater pump to OPERABLE within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or be in at least HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

TS 3.7.1.2, Action c was entered due to not meeting LCO 3.7.1.2.c following failure of the TDAFW pump to meet Surveillance Requirement (SR) 4.7.1.2.1.b. SP 3622.3-001 is the surveillance procedure that ensures SR 4.7.1.2.1.b is met and documents the 90-second acceptance criteria.

On December 30, 2025, at 12:35 hours, while in Mode 1, MPS3 entered TS 3.7.1.2, Action c due to a failure to meet response time testing for the TDAFW pump. The completion time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> will expire on January 2, 2026 at 12:35 hours.

3.

Provide sufficient information to demonstrate that the cause of the situation is well understood including extent of condition on other related SSCs (e.g.,

common cause).

Cause The slow response time, and thus inability to meet the 90-second acceptance criteria, was most likely caused by foreign material in the oil inside the governor.

Multiple electrical components in the shutdown control circuitry for the TDAFW pump were checked for proper operation, to refute these components as causes for the failure.

With no evidence of an electrical fault causing an undesired shutdown signal to be sent to the governor, the failure was determined to most likely have originated within the governor. In reviewing footage from the failure event and through discussions with the vendor, it is suspected that foreign material inside the governor became lodged in a manner that positioned the shutdown solenoid to dump control oil, resulting in TDAFW pump shutdown. This foreign material was likely dislodged from the shutdown solenoid seat as pressure inside the governor dropped, which resulted in the slower than expected TDAFW pump startup.

The likely foreign material in the governor was the initial cause of entering TS 3.7.1.2, Action c. MPS3 is currently still in the 72-hour Action c statement due to maintenance activities associated with the governor replacement and linkage adjustments. After replacing the governor, the system was still not fully operable because the initial linkage adjustment required additional fine tuning. This necessitates the need to perform several linkage adjustments to ensure proper synchronization, which is typical based on previous MPS3 Operating Experience and the time required extends beyond the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> AOT.

Serial No.26-001 Docket No. 50-423 Attachment, Page 4 of 14 Common Cause There are no concerns related to common cause failures of the other auxiliary feedwater pumps, which are both motor driven and therefore do not have governors. The Motor Driven Auxiliary Feedwater Pumps 3FWA*P1A and 3FWA*P1B were tested satisfactorily on December 29, 2025 and November 13, 2025, respectively.

4.

Provide an evaluation of all safety and security concerns associated with operating outside of the TS or license conditions that demonstrates that the noncompliance will not create undue risk to the public health and safety or involve adverse consequences to the environment. This should include, as appropriate, a description of the condition and operational status of the plant, equipment that is out-of-service, inoperable, or degraded that may have risk significance, may increase the probability of a plant transient, may complicate the recovery from a transient, or may be used to mitigate the condition. This evaluation shall include potential challenges to offsite and onsite power sources and forecasted weather conditions.

System

Description:

Auxiliary Feedwater System Description and Design Bases:

The steam generator auxiliary feedwater pumps are used as an emergency source of feedwater supply to the steam generators. The pumps are required to ensure safe shutdown in the event of loss of power or functions as an Engineered Safeguards System to remove core decay heat. The pumps are on standby service during normal plant operation.

The OPERABILITY of the Auxiliary Feedwater (AFW) System ensures a makeup water supply to the steam generators (SGs) to support decay heat removal from the Reactor Coolant System (RCS) upon the loss of normal feedwater supply, assuming the worst-case single failure. The AFW System consists of two motor driven AFW pumps and one steam turbine driven AFW pump. Each motor driven AFW pump provides at least 50% of the AFW flow capacity assumed in the accident analysis.

After reactor shutdown, decay heat eventually decreases so that one motor driven AFW pump can provide sufficient SG makeup flow. The steam driven AFW pump has a rated capacity approximately double that of a motor driven AFW pump and is thus defined as a 100% capacity pump.

In addition, given the worst-case failure, the AFW is designed to supply sufficient makeup water to replace SG inventory loss as the RCS is cooled to less than 350°F at which point the Residual Heat Removal System may be placed into operation.

Serial No.26-001 Docket No. 50-423 Attachment, Page 5 of 14 The TDAFW pump and associated flow paths are OPERABLE with all control and isolation valves fully open in MODE 1, 2 and 3. Due to High Energy Line Break analysis, the TDAFW pump cannot be used for steam generator inventory control during normal operation below 10% RATED THERMAL POWER.

Each motor-driven pump discharge line branches in two and each branch line feeds one steam generator. The cross connection between the two MDAFW pumps is maintained closed. The discharge from the turbine-driven pump divides into four lines, each line feeding one of the four discharge lines from the motor driven pump.

During normal auxiliary feedwater system use, the turbine driven auxiliary pump feedwater control valves (3FWA*HV32A/B/C/D and 3FWA*HV36A/B/C/D) are maintained fully open.

The turbine driven auxiliary feedwater pump starts automatically on:

a. loss of DC power, or

b. two out of four low-low water level signals in any two of four steam generators.

c. Anticipated Transient Without Scram (ATWS) Mitigation System Actuation Circuitry (AMSAC) automatic start signal With one of the auxiliary feedwater pumps inoperable in MODE 1, 2, or 3 for reasons other than ACTION a. or b., ACTION must be taken to restore OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This includes the loss of three steam supply lines to the turbine-driven auxiliary feedwater pump. The 72-hour allowed outage time is reasonable, based on redundant capabilities afforded by the auxiliary feedwater system, time needed for repairs, and the low probability of a design basis accident (DBA) occurring during this time. Two auxiliary feedwater pumps and flow paths remain to supply feedwater to the steam generators.

Plant and Grid Condition Weather Considerations Weather forecast from National Weather Service for Waterford, Connecticut as of 1/1/2026 14:30.

Serial No.26-001 Docket No. 50-423 Attachment, Page 6 of 14 Severe weather is not forecasted for the region within the proposed period of enforcement discretion.

Current Plant and Grid Status MPS3 is in Mode 1 at 100% power operation. There is no other equipment out of service, inoperable, or degraded that could challenge the operability of the MDAFW pumps. It was verified that no maintenance activities on off-site lines pose a challenge to the off-site power source.

Currently the grid is stable. Discussions with CONVEX indicate that no challenges to grid stability are expected for the next 7 days and no switchyard or grid work that would impact grid reliability are allowed during the NOED period. CONVEX will notify MPS3 if any of these conditions change.

Safety Analysis Discussion During the proposed period of enforcement discretion, the TDAFW pump will not be available to respond to plant transients. However, the two motor driven AFW pumps and their emergency power supplies will be available and protected. Therefore, sufficient capacity exists in the AFW system to ensure it can meet the requirements to remove decay heat, prevent steam generator dryout, maintain RCS subcooling, prevent the pressurizer from exceeding acceptable limits, and reduce RCS temperature to 300°F.

Serial No.26-001 Docket No. 50-423 Attachment, Page 7 of 14 under a loss of normal flow (LONF) scenario without consideration of an additional single failure. No changes are being proposed that affect any other assumptions or inputs to applicable safety analyses. Therefore, safety margins will be maintained.

Other Defense-in-Depth Considerations The AFW system is expected to maintain its ability to perform its safety function during the period of enforcement discretion. No other SSCs will be affected by the proposed period of enforcement discretion, and no limits will be imposed on any SSC that will hinder their ability to perform their specified function. Elevated risk awareness and the protection of critical equipment will be executed during the proposed period of enforcement discretion in accordance with existing plant procedures. Additionally, these programmatic controls will be augmented by pre-job and periodic (i.e., shift) briefings, Plant Equipment Operator (PEO) rounds, progress updates, and increased operation and managerial scrutiny. As such, there will be no over-reliance on programmatic activities as compensatory measures during the period of enforcement discretion. The independence of the physical barriers to radiological releases will not be degraded as a result of the proposed period of enforcement discretion. The planned activities on the replacement of the TDAFW pump governor will not impact fuel cladding, RCS, or Containment integrity.

Plant configurations that could potentially challenge the availability of the off-site power supplies, the on-site Emergency Diesel Generators or the MDAFW pumps will not be allowed. Overall plant risk will be managed in accordance with 10CFR50.65(a)(4).

Conclusion Based on the justification above, the requested extension will not create undue risk to the public health and safety or involve adverse consequences to the environment. There are no challenges to offsite or onsite power sources due to forecasted weather conditions.

5.

Provide a description and timeline of the proposed course of action to resolve the situation (e.g., likely success of the repairs) and explain how the resolution will not result in a different or unnecessary transient. The timeline of proposed repairs should also include all post maintenance tests which may be necessary prior to operability. This shall include the time period for the requested discretion and demonstrate a high likelihood of completion within the requested period of enforcement discretion. If the proposed course of action necessitates enforcement discretion greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, the licensee shall justify why a longer-term solution (e.g., emergency amendment) should not be processed within the duration of a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> NOED.

Serial No.26-001 Docket No. 50-423 Attachment, Page 8 of 14 The following timeline describes the major sequence of events planned to restore operability:

Date / Time (Start)

Event Duration (hours) 1/2/2026 1235 Period of Enforcement Discretion begins ongoing Third Adjustment to the linkage of the Governor to valve Clear tags Maintenance run Hang tags 8.5 (after entering discretion) 1/2/2026 2100 Fourth Adjustment to linkage Clear tags Maintenance run Hang tags 14.0 1/3/2026 1100 Fifth Adjustment to linkage Clear tags Maintenance run Hang tags 14.0 1/4/2026 0100 Pre-Conditioning Hold 5.5 1/4/2026 0630 Perform SP 3622.3-001 6.0 1/4/2026 1230 Declare Pump 3FWA*P2 OPERABLE 1/4/2026 1235 Enforcement Discretion Expiration ENFORCEMENT DISCRETION DURATION 48.0 The repairs described will restore operability of the TDAFW pump by replacing the governor. The replacement governor has been inspected for internal cleanliness to the extent practical and filled with new, filtered, oil thus ensuring no concerns with particulate since the governor oil system is wholly contained within the governor assembly itself.

After replacing the governor, the system was still not fully operable because the linkage between the governor and control mechanism required additional fine tuning. The repair plan involves a linkage adjustment window of 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> per adjustment. Based on past Operating Experience at MPS3, it could take as many as 5 fine-tuning adjustment windows to ensure proper synchronization. This adjustment window includes tagging, performing maintenance runs, and verifying repeatability of starts. The likely cause is foreign material in the oil and while the governor itself has been replaced and is satisfactory for the cause, the linkage needs precise calibration to restore reliable operation. This process extends beyond the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> AOT.

Serial No.26-001 Docket No. 50-423 Attachment, Page 9 of 14 MPS3 is requesting enforcement discretion for up to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. NRC Enforcement Manual, Appendix F, estimates that processing an amendment to change Technical Specifications will require approximately five (5) days. The processing timeframes (ref. App. F, Figure 1) for an Emergency LAR do not support issuance of an amendment within the period of enforcement discretion.

6. Detail and explain compensatory actions that the plant has both taken and will take to reduce risk(s), focusing on both event mitigation and initiating event likelihood. Describe how each compensatory measure achieves one or more of the following:

a. Reduces the likelihood of initiating events;

b. Reduces the likelihood of the unavailability of redundant trains, during the period of enforcement discretion; and,

c. Increases the likelihood of successful operator actions in response to initiating events.

Compensatory measures are not accounted for or credited in the PRA risk assessment.

The following compensatory actions are based on a review of dominant sequences and insights for this configuration. The goals for each compensatory measure relative to the three objectives in Question 6 are indicated in brackets following the action.

x Shiftly Crew Brief on the actions of EOP 35 ECA-0.0, Loss of All AC Power and EOP 35 FR-H.1, Response to Loss of Secondary Heat Sink including procedure progression given NOED configuration (3FWA*P2 out of service).

[c]

x Protect the following equipment in accordance with OP-MP-601, Protected Equipment: [b]

o Protect both motor-driven auxiliary feedwater pumps and their supply breakers.

o Protect both emergency diesel generators (EDGs), the EDG Sequencers, and the SBO diesel generator.

x Defer all planned switchyard work. [a, b]

x Do not enter configuration if severe weather conditions exist in accordance with AOP 3569, Severe Weather Conditions Section 2.0. [a]

x Perform risk management actions in accordance with MPS3 Technical Requirements Manual (TRM) Section 7.4.1.i for 3FWA*P2 - Turbine Driven AFW Pump. [a]

Serial No.26-001 Docket No. 50-423 Attachment, Page 10 of 14 o Establish the following risk management action (RMA) Defense-In-Depth compensatory measures for the next 30 days, to limit transient combustible material and ignition sources identified in the affected areas below:

a. Review existing transient combustible material permits for the affected areas.

b. Review existing ignition source permits for the affected areas.

c. Perform an area walkdown of the affected areas.

d. Evaluate all work requiring transient combustibles, hot work or racking of breakers in the affected areas.

e. On a daily basis, brief the shift operators and the fire brigade lead on the significance of a fire in the affected areas.

f. Restore FUNCTIONALITY of the affected Risk Significant component within the 30 days or prepare a FUNCTIONALITY assessment, in accordance with station procedures for the Risk Significant component out of service.

Affected Areas:

CB Control Bldg., El. 46, West SWGR Area CB Control Bldg., El. 46, East SWGR Area CB Control Bldg. Cable Spreading Area CB Control Room CB Instrument Rack Room and Underfloor Areas SB Service Bldg. North Cable Tunnel SB Service Bldg. South Cable Tunnel ESF ESF Bldg. South Cont. Recirc. Cooler Cubicle ESF ESF Bldg. North Cont. Recirc. Cooler Cubicle ESF ESF Bldg. East Floor Area, El. 46 ESF ESF Bldg. Refueling Water Recirc. Pumps Cubicle ESF ESF Bldg. North MD AFW Pump Cubicle ESF ESF Bldg. South MD AFW Pump Cubicle With the TDAFWP unavailable, perform shiftly Crew Brief on the actions of EOP 3509.1, Control Room, Cable Spreading Area or Instrument Rack Room Fire with focus on Attachment U Operate A MD AFW Pump. [a]

Serial No.26-001 Docket No. 50-423 Attachment, Page 11 of 14

7.

Demonstrate that the NOED condition, including compensatory measures will not result in more than a minimal increase in radiological risk, either in quantitative assessment that the risk will be within the normal work control levels (ICCDP less than or equal to 5E-7 and/or ICLERP less than or equal to 5E-8) or in a defensible qualitative manner. Further guidance is provided in Section 2.6.

PRA input to the NOED is based on the information requested in Section 2.6 of the NRC Enforcement Manual, Appendix F, Notices of Enforcement Discretion. The requests and corresponding responses are provided below.

1. Use the zero maintenance PRA model to establish the plants baseline risk and the estimated risk increase associated with the period of enforcement discretion. For the plant-specific configuration the plant intends to operate in during the period of enforcement discretion, the ICCDP and ICLERP should be quantified and compared with guidance thresholds of less than or equal to an ICCDP of 5E-7 and an ICLERP of 5E-8. These numerical guidance values are not pass-fail criteria. For the degraded case with the subject equipment out of service, the model should reflect current equipment unavailability states (i.e., if other equipment is unavailable because of concurrent testing and maintenance, this should also be reflected in the analysis) as much as possible. This risk calculation should not be limited to the specific TS relief in question, but rather, the total risk of continued operation for the specific configuration of the plant.

Response

The configuration analyzed is removal of Turbine-Driven AFW pump (TDAFWP) from service. This configuration was assessed using the MPS3 zero maintenance model and analyzed to a bounded enforcement discretion period of 5 days.

The MPS3 risk values are provided below.

Baseline CDF = 1.78E-06/yr Baseline LERF = 1.39E-07/yr Conditional CDF = 7.59E-06/yr Conditional LERF = 9.52E-07/yr Time in configuration = 5 days The estimated risk increase associated with the analyzed bounding 5-day period of enforcement discretion is calculated to be:

ICCDP = ((7.59E-06/yr - 1.78E-06/yr)

• 120/8766 yr)

ICCDP = 7.95E-08 ICLERP = ((9.52E-07/yr - 1.39E-07/yr)

• 120/8766 yr)

Serial No.26-001 Docket No. 50-423 Attachment, Page 12 of 14 ICLERP = 1.11E-08 These risk values are below the guidance threshold values of 5E-07 and 5E-08 for ICCDP and ICLERP, respectively. Therefore, an enforcement discretion time period of up to 5 days is acceptable.

NOTE: A sensitivity study was performed evaluating the NOED configuration with the potential for increased environmental factors during the period of enforcement discretion due to elevated winds and seas. For a bounding 5-day period of enforcement discretion, the ICCDP and ICLERP values were calculated to be 1.17E-07 and 1.30E-08 respectively which are still below the guidance threshold values and are, therefore, still considered acceptable.

2. Discuss the dominant risk contributors (cut sets or sequences or both) and summarize the risk insights for the plant-specific configuration the plant intends to operate in during the period of enforcement discretion. This discussion should focus primarily on risk contributors that have changed (increased or decreased) from the baseline model because of the degraded condition and resultant compensatory measures, if any.

Response

The dominant CDF sequences are:

1.

SBO scenarios with unavailability of the TDAFWP coincident with random failures of both EDGs and SBO diesel generators.

2.

General transient scenarios with unavailability of the TDAFWP coincident with random failure of both MDAFWPs or their support DC power.

3.

LOOP scenarios with unavailability of the TDAFWP coincident with failure of an EDG, failure of diesel-driven compressor which precludes swapover to condensate storage tank (CST) before demineralized water storage tank (DWST) depletion, and either failure of unaffected PORV which precludes establishing bleed and feed (BAF) or failure of equipment alignment for cold leg recirculation following BAF-induced LOCA.

The dominant LERF sequences are:

1.

Item 1 above.

2.

Item 3 above.

3. Discuss how compensatory measures are accounted for in the PRA. These modeled compensatory measures should be correlated, as applicable, to the dominant PRA sequences identified in items 1 and 2 above. It is understood that measures not directly related to the out-of-service equipment may be implemented to reduce overall

Serial No.26-001 Docket No. 50-423 Attachment, Page 13 of 14 plant risk and, as such, should be explained. Compensatory measures that cannot be modeled in the PRA shall be assessed qualitatively.

Response

Compensatory measures are not accounted for or credited in the PRA risk assessment.

The following compensatory actions are based on a review of dominant sequences and insights for this configuration.

x Shiftly Crew Brief on the actions of EOP 35 ECA-0.0, Loss of All AC Power and EOP 35 FR-H.1, Response to Loss of Secondary Heat Sink including procedure progression given NOED configuration (3FWA*P2 out of service).

x Protect the following equipment in accordance with OP-MP-601, Protected Equipment:

o Protect both motor-driven auxiliary feedwater pumps and their supply breakers.

o Protect both emergency diesel generators (EDGs), the EDG Sequencers, and the SBO diesel generator.

x Defer all planned switchyard work.

x Do not enter configuration if severe weather conditions exist in accordance with AOP 3569, Severe Weather Conditions Section 2.0.

4. Discuss the extent of condition of the failed or unavailable component(s) to other trains or divisions of equipment and the adjustments, if any, which were made to the related PRA common cause factors to account for potential increases in their failure probabilities. The method used to determine the extent of condition shall be discussed.

It is recognized that a formal cause or apparent cause is not required because of the limited time available in determining the acceptability of a requested NOED. However, a discussion of the likely cause shall be provided with an associated discussion of the potential for common cause failure.

Response

The TDAFWP and specifically its steam driven turbine is a uniquely designed component at the station that performs a unique function. There are no common cause or extent of condition concerns for the identified issue and no adjustments to the PRA model were made to account for this.

5. Discuss external event risk for the specified plant configuration. External events include fire (internal and external), external flooding, seismic, high winds, tornado,

Serial No.26-001 Docket No. 50-423 Attachment, Page 14 of 14 transportation, other nearby facility accidents. An example of external event risk is a situation in which a reactor core isolation cooling (RCIC) pump has failed, and a review of the licensees Individual Plant Examination of External Events or full-scope PRA model identifies that the RCIC pump is used to mitigate CDF and LERF in certain fire scenarios. Action may be taken to reduce fire ignition frequency in the affected areas and to reduce human error associated with time-critical operator actions in response to such scenarios, and to ensure fire protective and corrective measures have been taken.

Response

The MPS3 TRM was reviewed for actions to manage fire risk for risk significant components nonfunctional in the given plant configuration. The following will be performed:

x Perform risk management actions in accordance with MPS3 TRM Section 7.4.1.i as described in Question 6.

A dominant contributor to fire risk includes Main Control Room Abandonment (MCRA) scenarios with decay heat removal provided by the TDAFWP. With the TDAFWP unavailable, decay heat removal is provided via the A motor-driven AFW pump per EOP 3509.1, Control Room, Cable Spreading Area or Instrument Rack Room Fire Attachment U, Operate A MD AFW Pump. Given this configuration, perform shiftly Crew Brief on the actions of EOP 3509.1 with focus on Attachment U.

8.

Confirm that the facility organization that normally reviews safety issues has reviewed and approved this request and that a written NOED request will be submitted within two working days, excluding licensee holidays, of the NRC staffs decision regarding the NOED.

The Facility Safety Review Committee reviewed this NOED on January 1, 2026, and concurs with this request.