ML24240A264

Corporation - Request for Notice of Enforcement Discretion Regarding Technical Specification 3.7.5, Auxiliary Feedwater (AFW) System

ML24240A264
Person / Time
Site:	Wolf Creek
Issue date:	08/27/2024
From:	Mccoy J Wolf Creek
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
000609
Download: ML24240A264 (1)

Text

Jaime H. McCoy Site Vice President August 27, 2024 000609 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

Subject:

Docket No. 50-482: Request for Notice of Enforcement Discretion Regarding Technical Specification 3.7.5, Auxiliary Feedwater (AFW)

System Commissioners and Staff:

In a teleconference call on August 23, 2024, Wolf Creek Nuclear Operating Corporation (WCNOC) informed the NRC staff of the need for a notice of enforcement discretion (NOED) from the requirements of Wolf Creek Generating Station (WCGS) Technical Specification (TS) 3.7.5 Auxiliary Feedwater (AFW) System Condition C, which states, One AFW train inoperable for reasons other than Condition A and B, with Required Action C.1 to restore the AFW train to operable status with a Completion Time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. If this Completion Time is not met, Condition D is entered. Required Action D.1 is to be in Mode 3 with a Completion Time of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Required Action D.2 is to be in Mode 4 with a Completion Time of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

This NOED request was made to avoid an unnecessary plant transient as a result of compliance with TS 3.7.5 Action C.1, by allowing an extension period of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> prior to initiating shutdown of the unit.

The Plant Safety Review Committee (PSRC) reviewed and concurred with this request.

This NOED request was verbally approved by the Nuclear Regulatory Commission (NRC) on August 23, 2024, at approximately 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> Central Daylight Time (CDT). Per NRC Enforcement Manual, Appendix F Notices of Enforcement Discretion, WCNOC is required to submit a written request for the NOED within two working days of the oral request for a NOED.

The incremental conditional core damage probability (ICCDP) and incremental conditional large early release probability (ICLERP) have been quantified for the requested additional time for restoring the Turbine Driven Auxiliary Feedwater (TDAFW) Pump. The results of the quantification are within the guidance threshold in NRC Enforcement Manual Appendix F, Notices of Enforcement Discretion. It has been determined that there is no net increase in radiological risk.

The compensatory actions to review existing transient combustible permits, existing ignition sources, perform walkdowns for the affected fire areas, and to brief the shift operators and the fire brigade leader on the significance of a fire in the affected areas were completed on August 22, 2024.

000609 Page 2 of 2 Note: WCNOC did not utilize any of the approved enforcement discretion time. Following verbal approval from the NRC on August 23, 2024, additional post maintenance testing was performed which revealed a separate failure on a different component, which therefore invalidated the approved enforcement discretion. The 72-hour Completion Time of TS 3.7.5 Required Action C.1 expired at 0500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> CDT on August 23, 2024. The plant entered Mode 3 as required by TS 3.7.5 Required Action D.1 at 1024 hours0.0119 days <br />0.284 hours <br />0.00169 weeks <br />3.89632e-4 months <br /> CDT and Mode 4 as required by TS 3.7.5 Required Action D.2 at 1651 hours0.0191 days <br />0.459 hours <br />0.00273 weeks <br />6.282055e-4 months <br /> CDT on Friday, August 23, 2024.

The attachment provides the information documenting WCNOCs earlier verbal request for the NOED. This letter contains no commitments. If you have any questions concerning this matter, please contact me at (620) 364-4156, or Dustin Hamman at (620) 364-4204.

Sincerely, Jaime H. McCoy JHM/jkt

Attachment:

Request for Notice of Enforcement Discretion Regarding Technical Specification 3.7.5, Auxiliary Feedwater (AFW) System cc:

S. S. Lee, Project Manager (NRC), w/a G. B. Miller, Director DORS, Region IV (NRC), w/a J. D. Monninger, Regional Administrator, Region IV (NRC), w/a J. K. Rankin, Chief Division of Operating Reactor Licensing, Branch IV (NRC), w/a G. E. Werner, Region IV Branch Chief, Branch B (NRC), w/a D. L. Proulx, Senior Project Engineer, Region IV (NRC), w/a Senior Resident Inspector (NRC), w/a WC Licensing Correspondence, w/a - WO 24-000609

Attachment to 000609 Page 1 of 10 Request for Notice of Enforcement Discretion Regarding Technical Specification 3.7.5, Auxiliary Feedwater (AFW) System Introduction Wolf Creek Nuclear Operating Corporation (WCNOC) hereby requests the NRC staff to exercise discretion not to enforce compliance with the Wolf Creek Generating Station (WCGS) Technical Specification (TS) 3.7.5, Auxiliary Feedwater (AFW) System.

Discussion of the Requirements for which Enforcement Discretion is Requested The questions posed in Nuclear Regulatory Commission (NRC) Enforcement Manual Appendix F, Notices of Enforcement Discretion Checklist A are in bold. The information provided by WCNOC is following each question in plain text.

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

On August 20, 2024 at 0500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> Central Daylight Time (CDT), the plant entered a 72-hour shutdown limiting condition of operation after the safety-related Turbine Driven Auxiliary Feedwater (TDAFW) Pump was declared inoperable for planned maintenance.

This caused entry into TS 3.7.5 Auxiliary Feedwater (AFW) System Condition C for one AFW train inoperable. Required Action C.1 is to restore the AFW train to operable status with a Completion Time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. If this Completion Time is not met, Condition D is entered. Required Action D.1 is to be in Mode 3 with a Completion Time of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Required Action D.2 is to be in Mode 4 with a Completion Time of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

WCNOC declared emergent work for AL HV-10, TDAFW pump discharge valve to the B steam generator (SG), during post maintenance testing being performed under STS AL-103, TDAFW Pump Inservice Pump Test. Emergent work was declared due to erratic valve response of AL HV-10. Troubleshooting was performed on AL HV-10, however the erratic behavior was not repeatable during full valve diagnostics test with the pump secured, nor during the dynamic pump run with sensor equipment installed.

At 0316 hours0.00366 days <br />0.0878 hours <br />5.224868e-4 weeks <br />1.20238e-4 months <br /> CDT on August 22, 2024, while performing SYS AL-123, TDAFW Pump Post Maintenance Run, to start and run the TDAFW pump for troubleshooting AL HV-10, an overspeed condition occurred that caused the TDAFW pump to trip.

Troubleshooting was performed and determined that the cause of the overspeed trip was a failed actuator on FC FV-313, AFW Pump Turbine Speed Governing Valve. It was determined that the corrective actions necessary to replace the actuator and return the TDAFW pump to operable status could not be completed within the 72-hour Completion Time of Required Action C.1 of TS 3.7.5. This sequence of events precluded pursuit of an emergency license amendment.

Attachment to 000609 Page 2 of 10

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.

TS Limiting Condition of Operation (LCO) 3.7.5 requires three AFW trains be operable while the unit is in Modes 1, 2, and 3. Condition C is entered when one AFW train becomes inoperable for reasons other than Condition A (one steam supply to the TDAFW pump inoperable) or Condition B (one Essential Service Water (ESW) supply to the TDAFW pump inoperable). Required Action C.1 is to restore the AFW train to operable status with a Completion Time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. If this Completion Time is not met, Condition D is entered. Required Action D.1 is to be in Mode 3 with a Completion Time of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Required Action D.2 is to be in Mode 4 with a Completion Time of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

The AFW System consists of two motor driven AFW pumps and one steam turbine driven pump configured into three trains. Each motor driven pump provides 100% of the feedwater flow required for removal of decay heat from the reactor. The turbine driven pump provides 200% of the capacity of a motor driven pump. The design basis of the AFW System is to supply water to the steam generators to remove decay heat and other residual heat by delivering at least the minimum required flow rate to the steam generators at pressures corresponding to the lowest steam generator safety valve set pressure plus 3% accumulation. In addition, the AFW System must supply enough makeup water to replace steam generator secondary inventory lost as the unit cools to MODE 4 conditions. Sufficient AFW flow must also be available to account for flow losses such as pump recirculation and line breaks. The limiting Design Basis Accidents (DBAs) and transients for the AFW System are as follows: feedwater line break (FWLB),

main steam line break (MSLB), and loss of main feedwater. In addition, the minimum available AFW flow and system characteristics are considerations in the analysis of a small break loss of coolant accident (LOCA).

At 0500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> CDT on Tuesday, August 20, 2024, TS LCO 3.7.5 Condition C was entered to support planned maintenance on the TDAFW pump. The 72-hour Completion Time for Required Action C.1 will end at 0500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> CDT on Friday, August 23, 2024.

The plant would then have to be in Mode 3 by 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br /> CDT and Mode 4 by 1500 CDT on the same day.

WCNOC is requesting enforcement discretion from the shutdown requirements of Required D.1 and D.2 for TS 3.7.5 by allowing an extension period of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> prior to initiating shutdown of the unit. WCNOC requests this discretion to complete the required corrective maintenance on the TDAFW pump and associated post maintenance testing and return the TDAFW pump to operable status, without having to cause an unnecessary plant shutdown.

Enforcement discretion was verbally requested August 23, 2024, when the unit was at 100% power in Mode 1. The current plant awareness level was 2, representing medium CDF risk, due to the inoperability of the TDAFW pump. The additional 36-hour request is needed to support repair and testing activities currently in progress to restore the TDAFW pump to operable status. This would delay entry into Condition D until 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> CDT Saturday, August 24, 2024, and the subsequent entry into Mode 3 would not be required until 2300 hours0.0266 days <br />0.639 hours <br />0.0038 weeks <br />8.7515e-4 months <br /> CDT Saturday, August 24, 2024.

Attachment to 000609 Page 3 of 10

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)

On August 20, 2024 at 0500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> Central Daylight Time (CDT), the plant entered a 72-hour shutdown limiting condition of operation after the safety-related Turbine Driven Auxiliary Feedwater (TDAFW) Pump was declared inoperable for planned maintenance.

This caused entry into TS 3.7.5 Auxiliary Feedwater (AFW) System Condition C for one AFW train inoperable. Required Action C.1 is to restore the AFW train to operable status with a Completion Time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. If this Completion Time is not met, Condition D is entered. Required Action D.1 is to be in Mode 3 with a Completion Time of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Required Action D.2 is to be in Mode 4 with a Completion Time of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

WCNOC declared emergent work for AL HV-10, TDAFW pump discharge valve to the B steam generator (SG), during post maintenance testing being performed under STS AL-103, TDAFW Pump Inservice Pump Test. Emergent work was declared due to erratic valve response of AL HV-10. Troubleshooting was performed on AL HV-10, however the erratic behavior was not repeatable during full valve diagnostics test with the pump secured, nor during the dynamic pump run with sensor equipment installed.

Initial troubleshooting efforts during static diagnostic testing of AL HV-10 on 8/21/2024 showed no anomalies on the diagnostic traces. All set points were satisfactory, and the positioner calibration was within the normal range. Valve trace was very repeatable when compared to the previous test done in August 2022. Step response tests show the valve is responding well to both large and small changes in its demand signal.

At 0316 hours0.00366 days <br />0.0878 hours <br />5.224868e-4 weeks <br />1.20238e-4 months <br /> CDT on August 22, 2024, while performing SYS AL-123, TDAFW Pump Post Maintenance Run, to start and run the TDAFW pump for troubleshooting AL HV-10, an overspeed condition occurred that caused the TDAFW pump to trip.

During the second TDAFW pump run the morning of 8/22/2024, the data that was collected showed that the positioner calibration with the pump running was also within the normal range. With the pump running the I/P output is more erratic, showing an increase in output swing. However, during this pump run only one of these I/P output swings was large enough to cause the positioner to exhaust any air from the actuator.

This swing caused a 0.7 psi decrease in actuator pressure, which was not enough to cause the valve to change position. It would have taken an approximately 45 psi drop in actuator pressure to have allowed valve movement. There were no indications from either the static testing or the data acquired during the pump run that showed any issue that would have caused the valve cycling seen during the first pump run of this Technical Specification equipment outage (TSEO).

While performing SYS AL-123 to start and run the TDAFW pump for troubleshooting AL HV-10, an overspeed condition occurred that caused the TDAFW pump to trip. Nuclear Station Operators in the field reported hearing a slight change in the turbine RPMs just prior to the trip and control room personnel noticed a sharp increase in the discharge pressure of the TDAFW pump on the Nuclear Plant Information System (NPIS) just prior to the trip. AL HV-10 was under observation as part of the troubleshooting run on 8/22/2024 and did not exhibit signs of opening for the duration that the pump was

Attachment to 000609 Page 4 of 10 running.

During subsequent troubleshooting, the positioner on FC FV-313, AFW Pump Turbine Speed Governing Valve, was bench tested (8/22/24 at 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> CDT) yielding satisfactory results. Subsequently, the positioner was re-installed in the field within the system. Despite performing the system field test as instructed, the actuator failed to move as intended. Based on this observation, the positioner was ruled out as the cause of failure. Another potential failure cause was identified, indicating that the problem likely resided downstream of the positioner, possibly within the connections, wiring, or actuator. Based on troubleshooting of the Exlar actuator, manual actuation and start/trip actuation functions were as expected. The unexpected operation of the actuator happened during the pump run when speed control called upon the valve to open.

Based on troubleshooting of the positioner, there seemed to be an issue between the positioner speed control output signal and the actuators input demand signal. Following replacement of the Exlar actuator, system behavior resumed as expected. Based on this, the cause of the overspeed trip was a failed actuator on FC FV-313, AFW Pump Turbine Speed Governing Valve.

The Exlar electromechanical linear actuator consists of an enclosure with a motor and roller screw. The rotary torque of the motor is transmitted through the roller screw into linear movement of the coupled valve stem.

This failure is specific to the TDAFW pump and no extent of condition to other SSCs applies.

The safety function description per WCRE-34, WCNOC Fourth 10-YEAR INTERVAL INSERVICE TESTING PROGRAM, for FC FV-313, AFW Pump Turbine Speed Governing Valve, is that this valve must open to provide a flow of steam from the auxiliary feedwater turbine steam supply to the auxiliary feedwater turbine. The valve must also close to regulate the flow of steam from the auxiliary feedwater turbine steam supply to the auxiliary feedwater turbine. Upon initiation of the turbine driven auxiliary feedwater system, FC HV-312 opens to permit steam to the turbine. As FC HV-312 opens, the governor controls receive a start signal and FC FV-313 begins controlling turbine speed. Therefore, the valve must open and close to achieve proper operation of the turbine driven auxiliary feedwater system. Degradation and/or failure of this valve is assessed during operability testing of the turbine driven auxiliary feedwater system. This valve is considered skid mounted and is a subassembly of the auxiliary feedwater turbine. This valve is not designed to meet the requirements of ASME OM Code for testing and is tested along with the turbine driven auxiliary feedwater pump. Degradation and or failure of this valve is assessed during operability testing of the system. The OPEN safety function of this valve is that it must open to provide a steam flow path from the main steam system to the auxiliary feedwater pump turbine. The CLOSED safety function of this valve is that it must close to regulate the flow of steam from the auxiliary feedwater turbine steam supply to the auxiliary feedwater turbine.

The failed actuator on FC FV-313 rendered the valve incapable of reliably performing these safety functions.

4. Provide an explanation 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

Attachment to 000609 Page 5 of 10 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.

WCGS Unit 1 is in Mode 1 at 100% power operation. There is no additional safety related or risk significant non-safety related equipment inoperable which has a bearing on this NOED request. All available offsite and onsite AC power sources are operable, including three Station Blackout Diesel (SBO) generators that can support either safety train via manual alignment.

The normal charging pump is being restored from planned maintenance and is now currently considered available. There is a shift manager concern for a ground on NK04 that is currently undergoing troubleshooting. The 125V DC system allows for a single ground on the system before affecting operability. Troubleshooting has proven that this ground is not affecting the Essential Service Water (ESW) system, Emergency Diesel Generator (EDG) system, or 125 VDC charger and battery.

The National Weather Service indicates that temperature ranges from Thursday, August 22, 2024, until Monday, August 26, 2024, will be low to mid 70 degrees Fahrenheit temperatures and highs in the upper 90 degrees Fahrenheit. There is expected to be South winds at 10 mph with gusts as high as 25 mph which are not expected to challenge offsite sources.

There are currently no challenges to either the offsite or onsite power sources. While there are no challenges, for defense in depth, the station is equipped with three Station Blackout (SBO) Diesel Generators that are validated to be available monthly. The station also has a non-safety related AFW pump that is powered by the SBO Diesel Generators to provide a heat sink should no safety-related AFW pump be available.

Complying with the TS would result in an unnecessary shutdown that would increase risk without a corresponding health and safety benefit. In addition, Evergy Generation has expressed concerns that if WCGS shuts down, there could be significant challenges to the capability of the electrical distribution network to provide sufficient power to all of its customers due to wind and temperature forecasts.

5. Provide a description and timeline of the proposed course of action to resolve the situation (e.g., likely success of repairs) and explain how the resolution will not result in a different or unnecessary transient. 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 5 days, justify why a longer-term solution (e.g., emergency amendment) should not be processed with the duration of a 5 day NOED.

The following are the actions and durations for returning the TDAFW pump to operable.

16-hours for the replacement of the actuator

Attachment to 000609 Page 6 of 10 14-hours for the clearance order removal, steam line heat up, and post maintenance testing of the replaced parts and the in-service pump test as the final post maintenance test (PMT).

Performing these repairs and associated post maintenance testing at 100% power does not increase the likelihood of an unnecessary transient.

WCNOC is requesting enforcement discretion from the shutdown requirements of Required D.1 and D.2 for TS 3.7.5 by allowing an extension period of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> prior to initiating shutdown of the unit. WCNOC requests this discretion to complete the required corrective maintenance on the TDAFW pump and associated post maintenance testing.

An additional 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> will enable the station to return the TDAFW pump to operable status, without having to cause an unnecessary plant shutdown.

6. Detail and explain the compensatory actions the plant has taken and will take to reduce risk(s), focusing on both event mitigation and initiating event likelihood.

This shall include 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.

The compensatory measures to reduce the risk during the NOED period are described below.

The full response team will remain in place throughout the evolution and the remaining maintenance activities will be completed utilizing 24-hour personnel coverage.

The purpose for protecting equipment is to minimize plant risk. This involves limiting or prohibiting operation or maintenance of plant equipment when SSCs are made unavailable. For the duration of the TDAFW pump inoperability, avoidance of testing and maintenance impacting availability of the A train safety bus, including but not limited to, Essential Service Water (ESW), Motor Driven Auxiliary Feedwater Pump (MDAFP), Component Cooling Water (CCW),

Residual Heat Removal (RHR), Air Conditioning Units, and all 125 Volt DC System (NK) Batteries and the associated DG to maximize the mitigative response to a Station Blackout Event.

Ensure no switchyard work is allowed. This includes XMR01 (Startup Transformer) as well as the rest of the offsite power sources.

Posting protected train signs for both A and B trains of spent fuel pool cooling, Component Cooling Water (CCW), Emergency Diesel Generators, ESW, Class IE Switchgear (NB) buses, 125-volt DC system (NK) buses and both motor driven auxiliary feedwater pumps. Additionally, the protected equipment signs will be extended to all non-safety service water pumps, including their electrical power supplies SL31/41.

Enhanced operator sensitivity to safety bus electrical power supply issues to recognize and respond expeditiously to a Station Blackout Event or loss of offsite

Attachment to 000609 Page 7 of 10 power event (e.g., posting of protected train signage to NK rooms).

Control Room staff were trained on EMG FR-H1, Response to Loss of Secondary Heat Sink for alternate AFW supply via the fourth AFW pump during Training Cycle 23-4 which took place during July and August of 2023. This training increases the likelihood for success in response to initiating events.

Every crew prior to taking the watch will review the alarm response to loss of service water and alarm response to loss of heat sink.

Continual monitoring by the grid operator regarding grid conditions to anticipate challenges to offsite power availability.

Continual monitoring of the availability of the SBO diesels.

During this maintenance window the station will not allow or authorize any burn permits. All hot work has been suspended.

During this maintenance window, no additional surveillance testing or maintenance shall be performed that is not related to the specified equipment.

Fire Areas A-22 (A Control Room HVAC), C-27 (Control Room), C-9 (A ESF Switchgear Room), and C-10 (B ESF Switchgear Room) have been posted as protected Fire Risk Areas with an hourly fire watch per AP 22C-003, On-Line Nuclear Safety and Generation Risk Assessment, and AI 22C-013, Protected Equipment Program. Permission to cross Fire Risk Significant Component Area Signs must be authorized by the Work Control Center Senior Reactor Operator (or designee, i.e., Control Room Supervisor or Shift Manager).

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.

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, as best as possible, 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). 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.

Plant Alignment:

Both trains are protected (non-train work week)

Normal Charging Pump (PBG04) was conservatively assumed out-of-service for maintenance TDAFWP (PAL02) is OOS - the driver for this NOED Risk Numbers (Internal Events only):

Baseline CDF = 4.94E-06 Baseline LERF = 5.04E-08

Attachment to 000609 Page 8 of 10 Conditional CDF = 1.17E-05 Conditional LERF = 6.35E-08 Delta CDF = 6.76E-06 Delta LERF = 1.31E-08 Based on 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> duration:

ICCDP = 2.78E-08 ICLERP = 5.38E-11

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.

Top CDF Initiators:

Loss of non-safety Service Water (27.9%)

Loss of 4kV Bus NB02 (16.7%)

Loss of 4kV Bus SL41 (6%)

Loss of 4kV Bus SL31 (6%)

Transient (5.2%)

Top LERF Initiators:

Interfacing System LOCA (~55.2%)

Loss of 4kV buses SL41 and SL31 (~21.4%)

Important Operator Actions:

OPA-WSTOESW - Failure to start ESW pumps after subsequent loss of normal service water OPA-NSAFW-BF - Failure to align and start the Non-Safety AFW Pump OPA-OFB - Failure to initiate bleed and feed cooling without SI in progress (FWIS @T=0)

OPA-1WS01PABC-I - Failure to start the standby service water pump to avoid a plant trip (SSIE)

OPA-OFB-M - Failure to initiate bleed and feed cooling without SI in progress (FWIS @LO Tavg)

OPA-1WS01PABC - Failure to start a standby service water pump (post-trip)

3. Discuss how the 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 plant risk and, as such, should be explained. Compensatory measures that cannot be modeled in the PRA shall be assessed qualitatively.

Compensatory measures are not explicitly credited in the PRA and therefore are considered to be a source of conservatism.

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

Attachment to 000609 Page 9 of 10 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.

The failure of the TDAFWP is unique to the pump and is not existent elsewhere in the plant feedwater and/or auxiliary feedwater systems. Therefore, no common cause adjustment was made.

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

Qualitative risk insights indicate that mitigation of a Station Blackout Event (SBO) has significant impact on improvement of risk to the plant. The defense-in-depth for SBO is significant with the EDGs, SBO diesels, and the Non-Safety AFW pump. Additionally, the SHIELD RCP seals provide further mitigation of LOCA risk and, with a loss of AC power (such as with SBO) no operator action is required to maximize the likelihood of SHIELD Seal effectiveness.

The compensatory measures that are in place further enhance protection of SBO (or a lesser loss of AC event) mitigation capability. As previously mentioned, these compensatory measures are not explicitly considered in the internal events PRA.

Fire: Based on dominant scenarios, the following fire compartments rise in significance when considering the current plant alignment:

A Houses the auxiliary feedwater (AFW) pipe chase and results in the failure of both safety related motor driven AFW pumps. This is a transient fire with whole compartment burn. This compartment does not have detailed fire modeling, therefore detection and suppression are not credited.

CW/SW - Circulatory & Service Water supplies non-safety cooling water including service water (which supplies ESW loads during normal operations).

This is a transient fire with whole compartment burn. This compartment does not have detailed fire modeling, therefore detection and suppression are not credited.

YD The yard contains several large power transformers that lead to loss of power to non-safety service water pumps leading to increased reliance on safety-related Essential Service Water. This compartment does not have detailed fire modeling. Damage occurs to all targets in the zone of influence for scenarios with XSL31 and XSL41 (power supply to non-safety service water).

TURB - The turbine building is the largest fire area in the plant with the highest fire ignition frequency. Damage occurs to all targets in the zone of influence for scenarios with XPG11 and XPG12 (transients).

Attachment to 000609 Page 10 of 10 These scenarios include loss of motor driven AFW and/or service water which constitute approximately 10% of the total.

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 2 days of the NRC staffs decision regarding the NOED.

The Plant Safety Review Committee reviewed and approved this request on August 22, 2024. This letter and its attachment represent the written NOED request that is required to be submitted within 2 working days of the NRC staffs decision. WCNOC received verbal approval from the NRC at 0100 CDT August 23, 2024, for NOED allowing a 36-hour extension on the completion time for LCO 3.7.5 Required Action C.1 Note: WCNOC did not utilize any of the approved enforcement discretion time. Following verbal approval from the NRC on August 23, 2024, additional post maintenance testing was performed which revealed a separate failure on a different component (ALHV0010 AFW air-operated discharge valve), which therefore invalidated the approved enforcement discretion.

The 72-hour Completion Time of TS 3.7.5 Required Action C.1 expired at 0500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> CDT on August 23, 2024. The plant entered Mode 3 as required by TS 3.7.5 Required Action D.1 at 1024 hours0.0119 days <br />0.284 hours <br />0.00169 weeks <br />3.89632e-4 months <br /> CDT and Mode 4 as required by TS 3.7.5 Required Action D.2 at 1651 hours0.0191 days <br />0.459 hours <br />0.00273 weeks <br />6.282055e-4 months <br /> CDT on Friday, August 23, 2024.