NRC-23-0049, Request for Enforcement Discretion for Technical Specification 3.7.2, Emergency Equipment Cooling Water (Eecw)/Emergency Equipment Service Water (Eesw) System and Ultimate Heat Sink (UHS)

Request for Enforcement Discretion for Technical Specification 3.7.2, Emergency Equipment Cooling Water (Eecw)/Emergency Equipment Service Water (Eesw) System and Ultimate Heat Sink (UHS)

ML23205A139
Person / Time
Site:	Fermi
Issue date:	07/24/2023
From:	Peter Dietrich DTE Electric Company
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
NRC-23-0049
Download: ML23205A139 (1)

Text

Peter Dietrich Senior Vice President and Chief Nuclear Officer DTE Electric Company 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.6515 Email: peter.dietrich@dteenergy.com July 24, 2023 NRC-23-0049 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 Fermi 2 Power Plant NRC Docket No. 50-341 NRC License No. NPF-43

Subject:

Fermi Unit 2 Request for Enforcement Discretion for Technical Specification 3.7.2, Emergency Equipment Cooling Water (EECW)/Emergency Equipment Service Water (EESW) System and Ultimate Heat Sink (UHS)

DTE Electric Company (DTE) hereby requests enforcement discretion for Fermi Unit 2 (Fermi 2) from compliance with Technical Specification (TS) 3.7.2, Emergency Equipment Cooling Water (EECW)/Emergency Equipment Service Water (EESW) System and Ultimate Heat Sink (UHS).

For EECW, EESW and UHS systems during current plant operating CONDITIONs, TS 3.7.2 requires operability of both Residual Heat Removal (RHR) reservoirs. If one or more required reservoir is inoperable (TS 3.7.2 CONDITION A), TS 3.7.2 ACTION A.1 requires the reservoir to be restored to OPERABLE status within seventy-two (72) hours. If ACTION A.1 cannot be completed, TS 3.7.2 ACTION C.1 requires the plant to be in MODE 3 (hot shutdown) within the subsequent 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

On July 18, 2023, at 0424 Eastern Daylight Time (EDT), the Division II Residual Heat Removal Service Water (RHRSW) Mechanical Draft Cooling Tower (MDCT) fan D tripped due to vibrations. At that time the UHS was declared inoperable. During troubleshooting, it was discovered that TS 3.7.2 CONDITION A, TS 3.8.7 CONDITION A and CONDITION B, TS 3.8.4 CONDITION B, and TS 3.8.1 CONDITION B would not be met. The direct cause of the Div. II MDCT Fan D tripping on high vibrations was either the degraded mounting condition of the gear reducer to its pedestal or the degraded bushings on the driveshaft coupling to the gear reducer (or both). Corrective actions were required to correct the conditions and restore the equipment to an operable status.

The projected date and time that this condition can be corrected and restored to operable is at 2324 EDT on July 25, 2023. The current TS Required Action Completion Time expires at 0424 EDT on July 21, 2023. DTE hereby requests that the NRC exercise enforcement discretion as set out in the NRC Enforcement Manual, Appendix F, Notices of Enforcement Discretion.

USNRC NRC-23-0049 Page 2 The enforcement discretion requested by DTE will authorize temporary non-compliance with TS 3.7.2 CONDITION A, TS 3.8.7 CONDITION A and CONDITION B, TS 3.8.4 CONDlTION B, and TS 3.8.1 CONDITION B. ft is requested that this enforcement discretion be effective from 0424 EDT on July 21, 2023, to 2324 EDT on July 25, 2023.

This request for enforcement discretion has been reviewed and approved by the station's Onsite Safety Review Organization.

The incremental conditional core damage probability (ICCDP) and incremental conditional large early release probability (ICLERP) have been quantified for the requested additional time. The results of the quantification are within the guidance threshold in Nuclear Regulatory Commission (NRC) Enforcement Manual Appendix F, "Notices *of Enforcement Discretion."

The enforcement discretion request is provided in the enclosure, which provides the information requested in NRC Enforcement Manual Appendix F, "Notices of Enforcement Discretion."

This request was verbally transmitted to members of the NRC staff on July 20, 2023, at 1700 EDT, with subsequent approval being verbally granted by the NRC on July 20, 2023, at 1745 EDT.

The MDCT Fan D was declared operable on July 22, 2023, at 1557 EDT, following replacement of the degraded bushings and removal and regrouting of the gearbox foundation bolts.

No new commitments are being made in this submittal.

Should you have any questions or require additional information, please contact Mr. Eric Frank, Manager - Nuclear Licensing, at (734) 586-4772.

Senior Vice P *esident and Chief Nuclear Officer

Enclosure:

Request for Enforcement Discretion for Technical Specification 3.7.2, 3.8.4, 3.8.7, and 3.8.l cc: NRC Project Manager NRC Resident Office Regional Administrator, Region Ill

Enclosure to NRC-23-0049 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Request for Enforcement Discretion for Technical Specification 3.7.2, 3.8.4, 3.8.7, and 3.8.1 NRC-23-0049 Page 1 Request for Enforcement Discretion for Technical Specification 3.7.2, 3.8.4, 3.8.7, and 3.8.1 Summary of Issue On July 18, 2023, at 0424 Eastern Daylight Time (EDT), the Division II Residual Heat Removal Service Water (RHRSW) Mechanical Draft Cooling Tower (MDCT) Fan D tripped unexpectedly due to high vibrations while running at high speed. Prior to the trip, the fan ran for 41 minutes.

The MDCT fans are required to support operability of the Ultimate Heat Sink (UHS). The UHS reservoir is divided into two, one-half capacity reservoirs, corresponding to Division I and Division II. A two-cell MDCT is located above each of the one-half capacity reservoirs. Each cell is equipped with a MDCT fan. Two MDCT fans above each one-half capacity reservoir are required for that division to be considered operable. Each reservoir is the cooling source for that division's service water subsystems (e.g., the Emergency Diesel Generator Service Water (EDGSW), Emergency Equipment Cooling Water (EECW) system, Emergency Equipment Service Water (EESW), Residual Heat Removal (RHR) system, Core Spray system). The Division II EECW system cools the High-Pressure Coolant Injection (HPCI) system room cooler. Typically, when Division II UHS is declared inoperable, then the high-pressure coolant injection (HPCI) system is declared inoperable; however, an Engineering analysis was performed for HPCI operability which determined that there is reasonable assurance that HPCI will perform its design function for its given mission time and remain operable.

Technical Specification (TS) Limiting Condition for Operation (LCO) 3.7.2, Emergency Equipment Cooling Water (EECW)/Emergency Equipment Service Water (EESW) system and Ultimate Heat Sink (UHS) was entered and Division II UHS was declared inoperable.

In addition, the following TS are also being tracked under Operations Safety Function Determination sheets:

• 3.8.4 DC Sources - Operating

• 3.8.7 Distribution Systems - Operating

• 3.7.8 Emergency Diesel Generator Service Water (EDGSW) System which initiated 3.8.1 AC Sources Operating To respond to these issues, formation of an Emergent Issues Team (EIT) and staffing of the Outage Control Center (OCC) was initiated the morning of July 18, 2023. Walkdowns verified that the vibration switch, E11N130D, tripped due to vibrations. Further investigation determined that the cause is either from a sheared foundation bolt or bushing degradation and actions are required to correct the conditions and restore the equipment to an operable status.

NRC-23-0049 Page 2 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 DTE Electric Company (DTE) for Fermi Unit 2 (Fermi 2) follows each question.

1. Did the licensee explain why a formal 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.

The maintenance activities necessary to repair the MDCT are estimated to take up to an additional 115 hours0.00133 days <br />0.0319 hours <br />1.901455e-4 weeks <br />4.37575e-5 months <br /> beyond the end of the 72-hour COMPLETION TIME prescribed by REQUIRED ACTION A.1 to account time required to implement the fan repair and allow for severe weather in the forecast and grout cure time if needed. For this reason, DTE requests enforcement discretion to allow exceeding the 72-hour COMPLETION TIME of REQUIRED ACTION A.1 of TS 3.7.2 Emergency Equipment Cooling Water (EECW)/Emergency Equipment Service Water (EESW) System and Ultimate Heat Sink (UHS) by an additional 115 hours0.00133 days <br />0.0319 hours <br />1.901455e-4 weeks <br />4.37575e-5 months <br />. If at any point during this approved extension it is determined that the repair cannot be completed within the additional requested time, the plant will immediately enter TS 3.7.2 CONDITION C.1 and be in MODE 3 withing 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The following supported systems will also require an extension of their completion times to allow for repair of Division II MDCT Fan D and perform necessary post-maintenance testing:

- Immediate COMPLETION TIME of TS 3.7.8 Emergency Diesel Generator Service Water (EDGSW) System ACTION A.1 by an additional 115 hours0.00133 days <br />0.0319 hours <br />1.901455e-4 weeks <br />4.37575e-5 months <br />;

- 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> COMPLETION TIME of TS 3.8.1 AC Sources - Operating Action B.4 by an additional 115 hours0.00133 days <br />0.0319 hours <br />1.901455e-4 weeks <br />4.37575e-5 months <br />;

- 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> COMPLETION TIME of TS 3.8.4 DC Sources - Operating Action B.1 by an additional 113 hours0.00131 days <br />0.0314 hours <br />1.868386e-4 weeks <br />4.29965e-5 months <br />;

- 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> COMPLETION TIME of TS 3.8.7 Distribution Systems - Operating Action B.1 by an additional 113 hours0.00131 days <br />0.0314 hours <br />1.868386e-4 weeks <br />4.29965e-5 months <br />;

- 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> COMPLETION TIME of TS 3.8.7 Distribution Systems - Operating Action A.1 by an additional 107 hours0.00124 days <br />0.0297 hours <br />1.76918e-4 weeks <br />4.07135e-5 months <br /> Fermi 2 is currently operating in MODE 1 at 100% power. Without this enforcement discretion, Fermi 2 would be required to be in MODE 3 by 1624 EDT on July 21, 2023.

DTE reviewed alternatives to enforcement discretion to ensure that the request could not reasonably be avoided. However, at the time of the cause identification, the remaining duration was insufficient to prepare, submit, and receive NRC approval of a license amendment request under 10 CFR 50.90, Application for amendment of license, construction permit, or early site permit, even when considering the provisions for emergency situations discussed in 10 CFR 50.91(a)(5). Fermi 2 also does not yet have a Risk-Informed Completion Time (RICT) program to allow Completion Time extensions under DTE control (i.e., without prior NRC approval)

NRC-23-0049 Page 3 using risk assessments. The current set of plant conditions are unplanned and this MDCT failure has not previously occurred at Fermi 2. As a result, the cause was not immediately apparent and there was no contingency repair plan already in place. Enforcement discretion would allow continued plant operation for only that additional time needed to repair the equipment and restore it to operable status and within the 5-day maximum guideline established by NRC Enforcement Manual Appendix F, Notices of Enforcement Discretion. The remaining subsections of this enclosure provide additional information addressing how the criteria in Appendix F of the NRC Enforcement Manual are met.

The only alternative to this request for enforcement discretion is to shut down Fermi 2 by 1624 EDT on July 21, 2023. A shutdown of Fermi 2 is undesirable at this time and does not provide a corresponding health and safety benefit based on risk assessments that have been performed.

2. Did the licensee 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.

Fermi 2 is currently in MODE 1 (power operation). In MODEs 1, 2, and 3, the Fermi 2 TS 3.7.2, Emergency Equipment Cooling Water (EECW) /Emergency Equipment Service Water (EESW)

System and Ultimate Heat Sink (UHS), requires two EECW/EESW subsystems and UHS to be operable. When one or more are inoperable, as is the case with this request, the following TS 3.7.2 Condition applies:

• A.1 - Restore reservoir to OPERABLE status.

If REQUIRED ACTION A.1 cannot be completed within its 72-hour COMPLETION TIME, then TS 3.7.2 CONDITION C applies. CONDITION C contains two REQUIRED ACTIONS, C.1, to be in MODE 3 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 /> and C.2, to be in MODE 4 with a COMPLETION TIME of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

In the current condition, the issue with the Division II MDCT Fan D (which supports the operability of the RHR reservoir) resulted in entry to TS 3.7.2 CONDITION A at 0424 EDT on July 18, 2023. As a result, the COMPLETION TIME for REQUIRED ACTION A.1 will expire at 0424 EDT on July 21, 2023 (72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />). The repair to the Div. II MDCT Fan D cannot be implemented before that time and would require placing the plant in MODE 3 (hot shutdown) by TS 3.7.2 CONDITION B at 1624 EDT on July 21, 2023 (12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />), and in MODE 4 (cold shutdown) at 1624 EDT on July 22, 2023 (36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />).

In addition, the following TS are also being tracked under Operations Safety Function Determination sheets that would also expire prior to completion of repair activities:

TS 3.7.8 CONDITION A applies since the Division II EDGSW is declared inoperable. The REQUIRED ACTION declares the associated EDG inoperable (EDG 13 and EDG 14)

NRC-23-0049 Page 4 immediately. This action occurred and therefore TS 3.8.1 CONDITION B.4 is being tracked where both EDGs in one division is inoperable. The restricting COMPLETION TIME for the REQUIRED ACTIONS is 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to restore one EDG in the division to OPERABLE status.

This expires at 0424 EDT on July 21, 2023. If REQUIRED ACTION B.4 cannot be completed within its 72-hour COMPLETION TIME, then TS 3.8.1 CONDITION G applies.

CONDITION G contains one REQUIRED ACTIONS, G.1, to be in MODE 3 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 expires at 1624 EDT on July 21, 2023.

TS 3.8.4 CONDITION B applies since one DC electrical power subsystem is inoperable for reasons other than an inoperable battery charger. The REQUIRED ACTION B.1 restores direct current (DC) electrical power subsystem to OPERABLE within a COMPLETION time of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. Since UHS went inoperable first at 0424 EDT on July 18, 2023, then the Maximum Out of Service Time (MOST) per the Safety Function Determination process for the DC electrical power subsystem is 74 hours8.564815e-4 days <br />0.0206 hours <br />1.223545e-4 weeks <br />2.8157e-5 months <br /> (2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> plus 72-hours from the start of the 3.7.2 LCO) which expires at 0624 EDT on July 21, 2023. If REQUIRED ACTION B cannot be completed within its COMPLETION TIME, then TS 3.8.4 CONDITION C applies. CONDITION C contains one REQUIRED ACTION, C.1, to be in MODE 3 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 />.

TS 3.8.7 CONDITION A applies since the Division II AC buses are declared inoperable. The REQUIRED ACTION is to restore the AC electrical power distribution subsystem to OPERABLE status in 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> after the 72-hour TS 3.7.2 LCO. Since UHS went inoperable first at 0424 EDT on July 18, 2023, then the MOST for the DC electrical power subsystem is 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br /> (8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> plus 72-hours from the start of the 3.7.2 LCO) which expires at 1224 EDT on July 21, 2023.

TS 3.8.7 CONDITION B applies since one or more required DC electrical power distribution subsystem is inoperable. This went beyond the 2-hour COMPLETION TIME, causing entry into CONDITION C, (REQUIRED ACTION and associated COMPLETION TIME of CONDITION A or B not met), which expires in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after the 72-hour TS 3.7.2 LCO at 0424 EDT on July 22, 2023. The TS Bases for CONDITION C states that remaining in MODE 3 is acceptable because the plant risk in MODE 3 is similar to or lower than the risk in MODE 4 and because the time spent in MODE 3 to perform the necessary repairs to restore the system to an operable status will be short. The TS Bases does state that voluntary entry into MODE 4 may be made as it is also an acceptable low-risk state.

NRC-23-0049 Page 5

3. Did the licensee 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)?

Troubleshooting Process The following troubleshooting steps were performed:

• Inspection of the E1156C001D (Division II RHRSW MDCT Fan D) fan blades, drive shaft, and couplings was performed it was found that the neoprene grommets (bushings) on the gearbox side of the driveshaft coupling were degraded.

• An oil sample from the gear reducer was taken and analyzed. The particle count was found to be high and out of specification, however this is a new specification for the oil.

Particle count was found to be 23/16 with an expected value of less than 20/16. MDCT Fans A, B, and C have had higher particle counts in past oil samples without having vibration issues while running. This occurred in 2023 (A), 2009 (B), and 2023 (C), respectively.

• Inspection of the gear reducer was performed, and the internals were found to be satisfactory.

• The driveshaft was uncoupled from the fan and an uncoupled motor run was performed.

Analysis of the vibrations were found to be satisfactory.

• The gear reducer for Div. II MDCT Fan D is mounted to its pedestal via three (3) mounting bolts embedded into the pedestal with shims for alignment. Inspection of the mounting pedestal found that the nuts on all 3 mounting bolts were corroded.

Additionally, it was found that the front mounting bolt was sheared off and not connected to the foundation.

Cause The direct cause of the Div. II MDCT Fan D tripping on high vibrations was either the degraded mounting condition of the gear reducer to its pedestal or the degraded bushings on the driveshaft coupling to the gear reducer (or both). Either the front bolt on the gear reducer mount failed first or the bushings on the driveshaft coupling to the gearbox failed first due to their degraded condition. In either case, the failed component allowed motion (slop) to be introduced to the system while running, which is believed to have caused the other component to fail. The failure of the gear reducer mounting bolt caused the gear reducer to not be rigid to the NRC-23-0049 Page 6 foundation. This allowed the gear reducer to have vertical movement while operating which introduced a vibration to the fan.

The corroded-nuts bolts mounting the gear reducer to the pedestal are being repaired, as is the sheared-off front bolt. After these repairs, the drivetrain will be re-aligned and the bushings on the driveshaft coupling to the motor and to the gearbox will be repaired.

Common Cause An extent of condition was completed, and it was found that this issue is not isolated to the Div.

II MDCT Fan D. In 2021 it was found during visual inspection that the gearbox pedestal for the A MDCT had corrosion of the shims. This was determined to be cosmetic only and would not impact operation of the gear reducer. Additionally, it was found that the C MDCT gearbox pedestal was excessively corroded. The bolting attachments in the pedestal were found to be still tight and it was recommended that both the gearboxes on MDCT Fan A and C be repaired.

Division II MDCT Fan B and Division I MDCT Fans A and C have performed monthly operability surveillances and provided periodic RHRSW reservoir cooling functions without tripping the vibration switch and associated relay (Setpoint 3 Gs). The monthly operability surveillance includes running the MDCT fans in low and high speed. The most recent performance of these surveillances was on 06/21/2023 for Division II and 07/12/2023 for Division I.

In 2021, during an inspection, the MDCT C footing shims were found to be very corroded and expanded. The gear box footing was confirmed as still tight at that time. The shims on MDCT A gearbox were also found corroded, but to a lesser degree. It was recommended that the MDCT C gearbox and associated shims be replaced to allow for remediation of the gear box footing. Prior to the next scheduled refueling outage, the condition was further assessed and it was determined that the footing was still sound. As a result, it was determined to delay the replacement until the following refueling outage.

Vibration analysis has not been historically performed on these components. A schedule for vibration analyses is being developed to include these components in the future.

NRC-23-0049 Page 7

4. Did the licensee 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

3.7.2 Emergency Equipment Cooling Water (EECW)/Emergency Equipment Service Water (EESW) System and Ultimate Heat Sink (UHS)

The Emergency Equipment Cooling Water (EECW)/ Emergency Equipment Service Water (EESW) System is designed to provide cooling water for the removal of heat from equipment, such as Residual Heat Removal (RHR) and Core Spray (CS), pump coolers, and room coolers for Emergency Core Cooling System and other safety-related equipment, required for a safe reactor shutdown following a Design Basis Accident (DBA) or transient.

Components cooled by each EECW subsystem are normally cooled by the Reactor Building Closed Cooling Water (RBCCW) system, which cools various plant equipment primarily in the Reactor Building. An EECW subsystem contains a single 1775 gpm nominal capacity pump, a heat exchanger, a make-up tank, valves, piping, and associated instrumentation. A second 100%

capacity heat exchanger is also provided as a backup. Upon receipt of a loss of off-site power, a high drywell pressure signal, or low RBCCW System pressure, both EECW subsystems are activated. Upon activation, the EECW pump starts, the EECW loop isolates from the remainder of the RBCCW system, and other system valves reposition as needed to isolate non-essential loads and configure the system for emergency operation.

Each EECW subsystem's heat exchanger is cooled by the same division's Emergency Equipment Service Water (EESW) subsystem. The EESW subsystem contains a single 1600 gpm nominal capacity pump that pumps from the division's RHR Reservoir through the EECW subsystem's heat exchanger and returns to the RHR Reservoir. Each EESW subsystem functions to cool the associated EECW subsystem. The EESW pump automatically starts on the same actuation signals as the EECW System. The two EECW/EESW subsystems are separated from each other so that failure of one subsystem will not affect the OPERABILITY of the other subsystem.

The Ultimate Heat Sink (UHS) is provided by a single highly reliable water supply in the form of the RHR reservoirs and a means of heat rejection in the form of mechanical draft cooling towers.

The UHS consists of two one-half capacity reinforced concrete reservoirs each with a capacity of 3.41 X 106 gallons of water, corresponding to an elevation of 583 feet. The two reservoirs are connected by two redundant cross-tie lines to provide access to the combined inventory to either division of cooled equipment in the event of a failure in one of the divisions. Each RHR NRC-23-0049 Page 8 reservoir is the cooling source for that division's RHRSW subsystem, and EESW subsystem, as well as the diesel generator service water pumps for that division's emergency diesel generators (EDGs). A two-cell mechanical draft cooling tower is located over each division reservoir. Each cooling tower is designed to cool one division of supported equipment, thus providing full redundancy.

3.8.1 AC Sources-Operating:

The unit Class 1E AC Electrical Power Distribution System AC sources consist of the offsite power sources, and the onsite standby power sources (emergency diesel generators (EDGs) 11, 12, 13, and 14). As required by 10 CFR 50, Appendix A, GDC 17, the design of the AC electrical power system provides independence and redundancy to ensure an available source of power to the Engineered Safety Feature (ESF) systems.

The Class 1E AC distribution system is divided into redundant load groups (Division I and Division II), so loss of any one group does not prevent the minimum safety functions from being performed. Each load group is connected to an offsite power supply and two EDGs. Additional capability exists for each load group to be connected to the alternate division's offsite power supply (referred to as the maintenance cross-tie).

Offsite power is supplied to the 120 kV and 345 kV switchyards from the transmission network by five transmission lines. From the 120 kV switchyard, an electrically and physically separated circuit provides AC power, through system service transformer 64, to 4.16 kV ESF buses 64B and 64C. From the 345 kV switchyard, an electrically and physically separated circuit provides AC power through system service transformer 65 to 4.16 kV buses 65E and 65F. A detailed description of the offsite power network and circuits to the onsite Class 1E ESF buses is found in the UFSAR, Sections 8.2 and 8.3.

An offsite circuit consists of all breakers, transformers, switches, interrupting devices, cabling, and controls required to transmit power from the offsite transmission network to the onsite Class IE ESF bus or buses.

Transformers 64 and 65 are sized to accommodate the simultaneous starting of all ESF loads on receipt of an accident signal without the need for load sequencing.

The onsite standby power source for 4.16 kV ESF buses 64B, 64C, 65E, and 65F, consists of four EDGs; EDG 11, 12, 13, and 14, respectively. An EDG starts automatically on a loss of coolant accident (LOCA) signal (i.e., low reactor water level signal or high drywell pressure signal) or on an ESF bus degraded voltage or undervoltage signal. After the EDG has started, it automatically ties to its respective bus after offsite power is tripped as a consequence of ESF bus undervoltage or degraded voltage, independent of or coincident with a LOCA signal. The EDGs also start and operate in the standby mode without tying to the ESF bus on a LOCA signal alone.

Following the trip of offsite power, load shed relays strip nonpermanent loads from the ESF bus.

When the EDG is tied to the ESF bus, loads are then sequentially connected to its respective ESF bus by the automatic sequencer. The sequencing logic controls the permissive and starting signals to motor breakers to prevent overloading the EDG.

NRC-23-0049 Page 9 In the event of a loss of normal power, the ESF electrical loads are automatically connected to the EDGs in sufficient time to provide for safe reactor shutdown and to mitigate the consequences of a Design Basis Accident (DBA) such as a LOCA.

Certain required plant loads are returned to service in a predetermined sequence to prevent overloading of the EDGs in the process. Within approximately 55 seconds after the EDG breaker closure, all automatic and permanently connected loads needed to recover the unit or maintain it in a safe condition are returned to service (i.e., available to start according to designed start signals).

Ratings for the EDGs satisfy the requirements of Regulatory Guide 1.9. EDGs 11, 12, 13, and 14 have the following ratings:

a. 2850 kW-continuous;

b. 3135 kW-2 hour, short time;

c. 3100 kW-2000 hours;

d. 3250 kW-300 hours; and

e. 3500 kW-30 minutes.

Add any specific discussion that would help understand the cause/repair.

Plant Condition and Operational Status Fermi 2 is currently in MODE 1, 100% power and current Probabilistic Safety Analysis is green.

Division II EECW/EESW is inoperable with the associated supported equipment inoperable tracked on LCO 2023-0187:

• TS 3.8.1 AC SourcesOperating

• TRM 3.6.8 Drywell Spray

• TRM 3.7.7 Appendix R Alternative Shutdown Auxiliary Systems Additionally, the following are being tracked on being tracked on Safety Function Determination sheet with the MOST (Max Out of Service Time) applied:

• TS 3.5.1 ECCS Operating o Condition A - One low pressure ECCS injection/spray subsystem inoperable.

o Condition C - One CSS subsystem inoperable AND One LPCI subsystem inoperable.

• TS 3.6.2.3 Suppression Pool Average Temperature o Condition A - One RHR suppression pool cooling subsystem inoperable

• TS 3.6.2.4 Residual Heat Removal (RHR) Suppression Pool Spray o Condition A - One RHR suppression pool spray subsystem inoperable

• TS 3.6.4.3 Standby Gas Treatment (SGT) System o Condition A - One SGT subsystem inoperable.

NRC-23-0049 Page 10

• TS 3.7.1 Two RHRSW subsystems shall be Operable

• TS 3.7.8 Emergency Diesel Generator Service Water (EDGSW) System

• TS 3.8.4 DC Sources - Operating o Condition B - One DC electrical power subsystem inoperable

• TS 3.8.7 Distribution Systems -Operating o Condition A - One or more required AC electrical power distribution subsystems inoperable o Condition B - One or more required DC electrical power distribution subsystems inoperable

• TS 3.7.4 Control Center Air Conditioning (AC) System o Condition A - One control center AC subsystem inoperable.

It should be noted that all equipment listed is considered available just not operable. All Division I systems are OPERABLE with no equipment out of service; therefore, all redundant systems are currently OPERABLE.

HPCI is currently OPERABLE, this is based on a Sargent and Lundy analysis performed and attached to CR 2023-31630 that determined that with current plant conditions HPCI remains capable of performing its function with the Div. II UHS inoperable.

Current related equipment challenges in the plant include:

• EDG 12 Jacket water cooling pump degraded bearing, CR-2023-31607 documents an abnormal noise on the EDG 12 standby jacket coolant circulating pump. The pump does not have a safety function; however, it circulates jacket coolant water to the standby jacket coolant heaters to maintain jacket coolant temperature above 85-degree F. The pump is currently maintaining jacket coolant temperature in band with no abnormalities.

Therefore, there is currently no impact on the ability of EDG 12 to perform its safety functions. However, if the Jacket water coolant pump was to fail the EDG would cooldown over an indeterminate amount of time and would INOP the EDG when coolant temperature is less than 85-degree F.

• RHR Complex Dampers, o All dampers listed below have been blocked in accordance with SOP 23.420 to support OPERABILITY of the supported systems for given outside air temperatures. Review of the current weather forecast found there is no foreseen challenges with having to change damper positions during the discretionary enforcement period.

X4103F154 and X4103F153A/B EDG 13 Engine Room Damper Hydro motor failures X4103F132 EDG 13 Switchgear Room South Supply Fan Damper NRC-23-0049 Page 11 The plant schedule was reviewed and all risk significant work that could jeopardize plant operation in the condition was removed from the schedule.

Offsite Power Sources All offsite power sources are currently operable and offsite power is being supplied to both the 120 kV and 345 kV switchyards from the transmission network by five transmission lines.

Throughout the requested enforcement discretion period, access to the switchyards will be controlled by the Main Control Room and will be restricted to only essential work, with no elective maintenance being performed. Shift Manager approval will be, required to access the switchyards.

During the morning shiftly MISO communications, Operations will verify no work affecting the 120kV or 345kV switchyards. Weather conditions will be verified to be acceptable prior to authorizing work Onsite Power Sources Division I EDGs (11 & 12) are operable as well as the Combustion Turbine Generator 1 (CTG11-1). Division II EDGs are not operable due to the UHS being INOP, however they are still available. Throughout the requested enforcement discretion period, access to all these systems will be controlled by Fermi 2 and operations restrict the protected areas to only essential work, with no elective maintenance being performed. Shift Manager approval will be required to access these areas.

FLEX In addition to the EDGs and CTGs, the station has the FLEX N and N+1 diesel generators that either can supply Div. 1 & 2 ESF batteries via the FLEX Transfer Switch and the FLEX X-Tie Panel. The Transfer Switch selects which FLEX generator supplies the batteries To provide additional administrative barriers to guard against inadvertent inoperability or unavailability of equipment important to risk and nuclear safety, Operations has implemented Protected Equipment Barriers IAW ODE20, Protected Equipment.

In addition, it was verified that the Preventative Maintenance activities on the FLEX equipment were current with satisfactory results for all FLEX equipment and validated that all FLEX equipment was available and functional.

Weather Conditions The weather forecast from the National Weather Service for the area for the duration of the enforcement discretion is as follows:

• Thursday: (7/20/23): Scattered thunderstorms in the morning, becoming more widespread in the afternoon. Potential for severe thunderstorms in the afternoon. High of 85 F.

NRC-23-0049 Page 12 Winds SW at 10-20 mph. Chance of precipitation is 93%.

• Thursday night: Scattered thunderstorms with partly cloudy skies after midnight.

Low of 64 F. Winds WNW at 5-10 mph. Chance of precipitation is 60%.

• Friday: (7/21/23): Partly cloudy.

High of 81 F. Winds NNW at 10-15 mph. Chance of precipitation is 8%.

• Friday night: Partly cloudy.

Low of 61 F. Winds N at 5-10 mph. Chance of precipitation is 8%.

• Saturday: (7/22/23): Mostly sunny.

High of 82 F. Winds WNW at 5-10 mph. Chance of precipitation is 12%.

• Saturday night: Clear.

Low of 62 F. Winds SW 5-10 mph. Chance of precipitation is 7%.

• Sunday: (7/23/23) Mainly sunny in the morning with scattered showers and thunderstorms in the afternoon.

High of 82 F. Winds SW at 5-10 mph. Chance of precipitation is 40%.

• Sunday night: Clear to partly cloudy.

Low of 65 F. Winds SSW 5-10 mph. Chance of precipitation is 24%.

• Monday: (7/24/23): Mostly sunny with scattered thunderstorms later in day.

High of 84 F. Winds SW at 5-10 mph. Chance of precipitation is 50%.

• Monday night: Partly cloudy.

Low of 65 F. Winds SW at 5-10 mph. Chance of precipitation is 24%.

• Tuesday: (7/25/23): Partly cloudy with a stray shower or thunderstorm possible.

High of 84 F. Winds WSW at 5-10 mph. Chance of precipitation is 24%.

• Tuesday night: Mostly clear.

Low of 69 F. Winds S 5-10 mph. Chance of precipitation is 22%.

• Wednesday: (7/26/23) Partly cloudy.

High of 88 F. Winds SSW at 5-10 mph. Chance of precipitation is 24%.

• Wednesday night: Variable clouds with thunderstorms, especially overnight.

Low of 72 F. Winds S 5-10 mph. Chance of precipitation is 50%.

Based on the forecasted weather, there is a low probability that severe weather could impact offsite power sources but does have the potential delay the completion of the maintenance activities. This request for enforcement discretion is not in regard to severe weather or natural phenomena-related emergencies.

Repairs The planned resolution is to complete repairs necessary to restore the Division II RHRSW MDCT Fan D to operable status. This will be accomplished via the existing plant work control NRC-23-0049 Page 13 processes, which have been successfully implemented in the past. This action will not result in a different, unnecessary transient.

Environmental Considerations Although the proposed action involves noncompliance with the requirements of a TS LCO:

• There is no significant change in the types or a significant increase in the amounts of any effluent that may be released offsite, since the proposed actions neither affect the generation of any radioactive effluent nor do they affect any of the permitted release path.

• There is no significant increase in individual or cumulative occupational radiation exposure. The actions proposed in this request for enforcement discretion will not significantly affect plant radiation levels, and therefore do not significantly affect dose rates and occupational exposure.

As a result, no adverse consequences to the environment will occur.

No Undue Risk to the Public Health and Safety The requested enforcement discretion will not result in more than a minimal increase in risk, as demonstrated in the risk discussion in a subsequent subsection later in this enclosure. There are no foreseen challenges to the available offsite and onsite power sources. Measures have been implemented to prevent any maintenance activities on systems in the plant that could impact the Division I safety systems. There is no significant increase in radiological risk by applying enforcement discretion to the TS 3.7.2, CONDITION A COMPLETION TIME to accomplish the required repairs. Appropriate plant redundant and support systems (i.e., including non-TS equipment) will be considered as protected systems to ensure there is no undue risk of redundant or support equipment inoperability during the duration of the proposed enforcement discretion.

Conclusion Based on the above response, the enforcement discretion for the TS 3.7.2, CONDITION A COMPLETION TIME will not create undue risk to the public health and safety or involve adverse consequences to the environment.

NRC-23-0049 Page 14

5. Did the licensee 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? 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, the licensee shall justify why a longer-term solution (e.g., emergency amendment) should not be processed within the duration of a 5 days NOED.

Actions to restore Division II RHRSW MDCT D to OPERABILITY on July 19, 2023 included replacing the bushings on the motor and gearbox end, along with the yoke replacement on the gearbox end. These maintenance activities were followed by a mechanical drive train alignment in preparation for Post Maintenance Testing (PMT) and eventual return to operability on July 20, 2023 at 1100 EDT (LCO 3.7.2 expires 0424 EDT on July 21, 2023).

While conducting the mechanical drive train alignment, a hold-down bolt was found separated between the pedestal and the grouting. This bolt will require repair prior to completing the mechanical drive train alignment activities. The repairs will extend the timeline to return Div. II MDCT fan D to operability beyond the expiration of the LCO.

The current repair schedule includes uncoupling the drive shaft from the gearbox, removing the fan blades and shroud to replace the separated bolt. Following the successful repair of the hold-down bolt, the Maintenance team will reassemble and complete the mechanical drive train alignment in preparation of Post Maintenance Testing (PMT). The expected timeline to return Div. II MDCT fan D to operability and clear the LCO is now 2324 EDT on July 25, 2023.

Forecasted severe weather on the evening of July 20, 2023, may impact the above timeline.

The request for the Notice of Enforcement discretion includes the successful completion of the Division II RHR Cooling Tower Fan Operability surveillance test on Div. II MDCT fan D.

This additional maintenance is expected to be completed 115 hours0.00133 days <br />0.0319 hours <br />1.901455e-4 weeks <br />4.37575e-5 months <br /> after the original LCO completion time (this ensures sufficient margin exists).

The repair plan to the Div. II MDCT fan D is specific to this fan and is not expected to impact any other systems or structures that could potentially cause a different or unnecessary plant transient.

NRC-23-0049 Page 15

6. Did the licensee detail and explain compensatory actions the plant has both 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.

Compensatory Actions Taken The following compensatory measures have already been taken to reduce the risk during the period of enforcement discretion:

Protected equipment postings are deployed per plant procedures due to Division II EECW/EESW/UHS inoperable:

• Division I EECW/SW/UHS,

• Division I Switchgear,

• Division I EDGs,

• Reactor Core Isolation Cooling,

• Division I CSS,

• Division I RHR,

• Division I SGTS,

• Division I CCHVAC,

• High Pressure Coolant Injection

• Hardened Containment Vent System

• Standby Feedwater

• Combustion Turbine Generator 11-1

• FLEX Equipment Any work that is required to be performed in these areas will follow the process defined in MOP05 Control of Equipment and be authorized by the Shift Manger prior to work being performed.

• Minimize transient combustibles

• Prohibit hot work or limit with adequate compensatory measures per ODE-20

• Confirm availability of detection and suppression systems

• Confirm fire barriers intact

• Inspect area for fire source degradation NRC-23-0049 Page 16

• Minimize electrical switching at panels as applicable or establish compensatory measures per ODE-20 Compensatory Actions That Will be Taken The following compensatory measures will be taken to reduce the risk during the period of enforcement discretion:

• The Outage Control Center will remain staffed throughout the evolution and the maintenance activities will be completed utilizing 24-hour coverage. The offsite power supply and switchyard will be protected. This includes ensuring that switchyard access is restricted to only essential work and no elective maintenance within the switchyard is performed that would challenge offsite power availability. This will reduce the likelihood of a loss of offsite power occurring.

• No intrusive surveillances or maintenance activities will be allowed that could potentially jeopardize plant operations, except for emergent issues. This reduces the likelihood of the unavailability of redundant trains during the period of enforcement discretion.

• Fire risk management actions will be established in areas with high fire risk significance. Additional areas that will be protected for Fire Risk Management actions from the PRA analysis will be: compartments RB06, 03AB, 04AB, and 11ABE. These actions reduce the probability of a consequential fire in the risk significant areas of the plant.

Fire Area Description RB06 Reactor Building 2nd Floor 03AB Relay Room 04ABN Division I Switchgear Room 11ABE Div. 1 Portion Miscellaneous Room (DC MCC Room)

During the period of enforcement discretion, Fermi personnel will take the following steps to reduce the probability and severity of initiating events:

• Will not perform any elective maintenance on components that are credited for accident mitigation.

• Will not perform any unnecessary switchyard work or work on Balance of Plant systems that may increase the probability that there is a Unit trip.

• Will not perform any hot work in areas identified as significant in the PRA analysis.

• A Compensatory Monitoring plan will be reviewed for flooding mitigation every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to include inspection of all credited watertight doors.

NRC-23-0049 Page 17

• New Condition Reports and plant emergent issues will be reviewed twice per day for new conditions that may have impact on the current condition, any changes will be communicated to the NRC NRR Project Manager.

7. Did the licensee 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?

The risk associated with operating the plant with the Division II Residual Heat Removal Service Water (RHRSW) Northwest Mechanical Draft Cooling Tower (MDCT) Fan (E1156C001D) unavailable for a period of up to 2.71 days for enforcement discretion was found to meet the thresholds of NRC Enforcement Manual Appendix F. To augment this evaluation, risk will be minimized during the proposed period of enforcement discretion by protecting equipment in accordance with MOP05-100, Protected Equipment and ODE20, Protected Equipment. These compensatory measures will be in effect prior to entry into the period of the proposed enforcement discretion. - See Attachment 1 for more details.

Note: When considering Common Cause Factors and the resulting increased probabilities, the analysis results in exceeding ICLERP thresholds in 2.71 days. It is noted that this threshold is not considered pass/fail criterion for the duration of enforcement discretion requested, but that this increase in risk is acknowledged and compensatory measures discussed in Question 6 have been established to mitigate this additional risk. If, at any time during the period of enforcement discretion, it is identified that the restoration of the equipment cannot occur prior to the expiration date/time, then TS 3.7.2 CONDITION C will be immediately entered, requiring the plant to be in MODE 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

8. Did the licensee 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?

This request for enforcement discretion has been reviewed and approved by the Fermi 2 Onsite Safety Review Organization (OSRO) on July 20, 2023. This letter fulfills the requirement that a written NOED request be submitted by DTE within 2 days of the NRC staffs decision.

In addition, DTE has considered whether it is appropriate for a follow-up license amendment to be submitted under 10 CFR 50.90 following this NOED. At this time, DTE has not identified a need for such a follow-up license amendment request.

References

1. Nuclear Regulatory Commission Enforcement Manual, Appendix F, Notices of Enforcement Discretion, dated October 1, 2019 (ML19193A003)

TECHNICAL EVALUATION COVERSHEET TE Number: TE-E11-23-048 Revision: 1 Page 1 of 14 Initiating Document: Affected System/PIS number(s):

CR-2023-31630 E1156 / E1156C001D

Title:

Risk Evaluation for Notice of Enforcement Discretion Regarding the Division 2 Residual Heat Removal Service Water Northwest Mechanical Draft Cooling Tower Fan Abstract:

The purpose of this technical evaluation is to assess the core damage and large early release risk associated with operating the plant with the Division 2 Residual Heat Removal Service Water (RHRSW) Northwest Mechanical Draft Cooling Tower (MDCT) Fan (E1156C001D) unavailable in support of repairs for enforcement discretion. This evaluation also addresses risk insights from the Probabilistic Risk Assessment (PRA) model regarding dominant risk contributors and compensatory measures to be taken during the proposed period of enforcement discretion.

Continued Conclusions/Restrictions:

The risk associated with operating the plant with the Division 2 Residual Heat Removal Service Water (RHRSW) Northwest Mechanical Draft Cooling Tower (MDCT) Fan (E1156C001D) unavailable for a period of up to 2.71 days for enforcement discretion was found to meet the thresholds of NRC Enforcement Manual Appendix F. To augment this evaluation, risk will be minimized during the proposed period of enforcement discretion by protecting equipment in accordance with MOP05-100, Protected Equipment and ODE20, Protected Equipment. These compensatory measures will be in effect prior to entry into the period of the proposed enforcement discretion.

Continued Preparer (Print/Sign) Qualification: PSA-01/PSA-09 N/A (refer to Step 6.2.3.5)

Kasi Rhodes / See Attached Email Date: 07/21/23 Reviewer (Print/Sign) Qualification: PSA-01/PSA-09 N/A (refer to Step 6.2.6.8)

Mickey Koenemann / See Attached Email Date: 07/21/23 ITPR (Print/Sign) N/A

/ Date:

Approver (Print/Sign)

Michael Lake / See Attached Email Date: 07/21/23 Human Performance and MES56 "Pre-Screen" MES56001 provided with Tech Evaluation* , Full MES56 Risk Review: Required Optional

(*MES56001 not required to be attached to Tech Evaluation, only available for Supervisor review and to ensure it will be forwarded to HUDC in accordance with MES56)

Work Planner Acknowledgement (Print/Sign) N/A

/ Date:

DTC: TDEVAL DSN: TE-E11-23-048 Rev: 1 File: 1803.01 IP: I ISFSI Related Yes No Date: 07/21/2023 DTC: TPMMES DSN: MES58001 Rev. 5 P1/1 IP: I File:1703.22 Issued: 1/12/2022

TE-E11-23-048 Revision 1 Page 2 of 14 A. Purpose The purpose of this technical evaluation is to assess the core damage and large early release risk associated with operating the plant with Division 2 Residual Heat Removal Service Water (RHRSW)

Northwest Mechanical Draft Cooling Tower (MDCT) Fan (E1156C001D) unavailable in support of repairs for enforcement discretion. This evaluation also addresses risk insights from the Probabilistic Risk Assessment (PRA) model regarding dominant risk contributors and compensatory measures to be taken during the proposed period of enforcement discretion.

B. Quantitative Risk Evaluation This section details a quantitative risk evaluation performed for the purpose of comparing Incremental Conditional Core Damage Probability (ICCDP) and Incremental Conditional Large Early Release Probability (ICLERP) of the plant condition with the thresholds set forth in the NRC Enforcement Manual Appendix F (EM APP F) [1].

ICCDP and ICLERP are determined from Equation 1 and Equation 2, respectively:

= x Equation 1

= x Equation 2 Where CDFdeg is the Core Damage Frequency in the degraded plant configuration CDFbase is the CDF baseline value with no degraded equipment or equipment unavailable due to maintenance LERFdeg is the Large Early Release Frequency in the degraded plant configuration LERFbase is the LERF baseline value with no degraded equipment or equipment unavailable due to maintenance CT is the additional time requested for enforcement discretion In accordance with EM APP F, risk of the plant-specific configuration the plant intends to operate in during the period of enforcement discretion was quantified. The degraded plant configuration reflects the following equipment that is currently unavailable:

Division 2 RHRSW NW MDCT Fan (E1156C001D)

Main Steam Drain Line Inboard Isolation Valve (B2103F016)

Main Steam Drain Line Outboard Isolation Valve (B2103F019)

Division 2 Emergency Equipment Cooling Water (EECW) Heat Exchanger (P4400B001B)

Combustion Turbine Generator (CTG) (R1100S070)1 The following are the additional relevant assumptions for the calculation:

1. Per EM APP F, the zero maintenance PRA model, FermiV12 [2], was utilized to perform the assessment.

2. Calculations were performed with a 1E-12/yr truncation limit for CDF and a 5E-13/yr truncation limit for LERF.

3. Adjustments to Common Cause Factor probabilities are discussed in Section E.

4. The Fermi 2 internal events PRA has been peer reviewed against Regulatory Guide 1.200, Revision 2. All findings are closed and non-Capability Category II supporting level requirements have been addressed and resolutions are incorporated into the current model of record, FermiV12.

1 CTG 11-2 (R1100S070) is not credited for Black-Start Capability.

TE-E11-23-048 Revision 1 Page 3 of 14

5. FLEX equipment is not included in the FermiV12 Model of Record but can be credited to understand its impact. The quantification results listed in below do not credit FLEX equipment.

Table 1 contains the results of the FermiV12 Internal Events Quantification along with the resulting ICCDP and ICLERP values for comparison with the EM APP F thresholds. The conversion factor used to convert days to years is 365.25 days/year.

Table 1: Summary of Quantification Results and Risk Calculation Base [/yr] Degraded [/yr] CT [days] ICCDP/ ICLERP 23.06 5.00E-07 CDF 1.68E-06 9.60E-06 5.00 1.08E-07 2.71 5.00E-08 LERF 5.02E-07 7.24E-06 5.00 9.22E-08 2

As shown in Table 1, these thresholds are met for a completion time of up to 2.71 days.

A sensitivity calculation was performed to understand the impacts of crediting FLEX equipment. The completion times to meet the aforementioned thresholds for ICCDP and ICLERP are 23.56 and 2.72 days, respectively.

C. Dominant Risk Contributors The following are Fermi 2 specific design features that enhance Fermi 2s ability to successfully mitigate most initiating events.

1. Fermi 2 has two physically and electrically independent sources of Offsite power (120 kV and 345 kV lines). These offer the site greater electrical redundancy.

2. Fermi 2 has two Emergency Diesel Generators (EDGs) per Division.

3. Fermi 2 has four CTGs, one of which is self black-start capable. The other three are capable of black start with the assistance of a black start diesel generator. The CTGs normally provide power to Division 1 loads, and the PRA model credits operator action to crosstie to Division 2.

4. Fermi 2 has a high pressure inventory makeup system Standby Feedwater (SBFW), in addition to High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC). SBFW is a motor driven system which can also be utilized at low reactor pressures and can be powered by any of the four CTGs.

2 Per EM APP F, these numerical guidance values are not pass-fail criteria.

TE-E11-23-048 Revision 1 Page 4 of 14 CDF Contributors The most dominant CDF initiating event contributors that increased with unavailability of the Division 2 RHRSW NW MDCT Fan are listed in Table 2.

Table 2: Dominant CDF Initiating Event Contributor Factor Increases Degraded Initiating Event Description Base Frequency Change Factor Frequency Nominal Rupture in EECW Division 1 Line in the Auxiliary Building (AB) Division 1 5.39E-12 4.85E-11 8.99 Switchgear Room Large Loss of Coolant Accident (LOCA) in 1.59E-09 8.18E-09 5.14 Feedwater Line Large LOCA Below Top of Active Fuel 3.92E-09 2.01E-08 5.12 (TAF) - Water Medium LOCA in Low Pressure Coolant 3.83E-08 1.59E-07 4.16 Injection Line Loss of General Service Water (GSW) 1.70E-09 6.03E-09 3.55 Major Rupture in GSW Line in the AB Reactor Building Closed Cooling Water 4.31E-10 1.52E-09 3.53 (RBCCW) Heat Exchanger Room There were no initiating events whose contribution to CDF decreased due to the unavailability of the Division 2 RHRSW NW MDCT Fan.

Following discussion with the NRC, instead of evaluating CDF contribution factor increases, which can include low contribution initiators, an additional review of the existing data was performed to evaluate total CDF contribution increases. The results of this review are listed in Table 3.

Table 3: Dominant CDF Initiating Event Contributor Contribution Increases Degraded Initiating Event Description Base Frequency Change Frequency Loss of Bus #101 9.72E-08 2.39E-06 2.29E-06 Loss of Bus #301 4.69E-08 2.19E-06 2.15E-06 Total Loss of Offsite Power (LOSP) 1.98E-07 1.14E-06 9.39E-07 Small LOCA Below TAF - Water 4.29E-08 4.72E-07 4.29E-07 Partial LOSP for Division 1 2.02E-08 2.98E-07 2.78E-07 Partial LOSP for Division 2 2.20E-08 2.58E-07 2.36E-07 Review of Table 3 identified the Total and Divisional LOSP Initiators are also dominant CDF contributors. No changes to the existing compensatory actions listed in Section D are recommended as these have been deemed adequate to address the LOSP risk contributors.

TE-E11-23-048 Revision 1 Page 5 of 14 LERF Contributors The most dominant LERF initiating event contributors present with unavailability of the Division 2 RHRSW NW MDCT Fan are listed in Table 4.

Table 4: Dominant LERF Initiating Event Contributor Increases Degraded Initiating Event Description Base Frequency Change Factor Frequency Major Rupture in RBCCW/EECW Division 1 Line in the Reactor Building (RB) that 6.61E-12 1.55E-10 23.50 Propagates to the RHR Division 1/2 Areas Nominal Rupture in RBCCW/EECW Division 1 Line in the Reactor Building 3.69E-11 8.57E-10 23.22 (RB) that Propagates to the RHR Division 1/2 Areas Nominal Rupture in EECW Division 1 Line in the Auxiliary Building (AB) Division 1 6.10E-12 8.12E-11 13.30 Switchgear Room Medium LOCA in Core Spray Line 1.87E-10 2.00E-09 10.70 Medium LOCA Above TAF - Steam 5.57E-10 5.18E-09 9.30 Small LOCA Below TAF - Water 1.22E-08 1.09E-07 8.94 Major Rupture in Fire Protection System 3.82E-11 2.56E-10 6.69 Line in AB Division 1 Switchgear Room Nominal Rupture in Fire Protection System 1.41E-10 8.13E-10 5.78 Line in AB Division 1 Switchgear Room Small LOCA Above TAF - Steam 1.16E-09 4.12E-09 3.56 There were no initiating events whose contribution to LERF decreased due to the unavailability of the Division 2 RHR NW MDCT Fan.

Following discussion with the NRC, instead of evaluating LERF contribution factor increases, which can include low contribution initiators, an additional review of the existing data was performed to evaluate total LERF contribution increases. The results of this review are listed in Table 5.

Table 5: Dominant LERF Initiating Event Contributor Contribution Increases Degraded Initiating Event Description Base Frequency Change Frequency Loss of Bus #301 1.81E-08 2.60E-06 2.58E-06 Loss of Bus #101 3.83E-08 2.48E-06 2.45E-06 Small LOCA Below TAF - Water 1.22E-08 4.07E-07 3.95E-07 Partial LOSP for Division 2 6.17E-09 2.79E-07 2.73E-07 Partial LOSP for Division 1 6.65E-09 2.74E-07 2.68E-07 Total LOSP 1.03E-08 2.32E-07 2.22E-07

TE-E11-23-048 Revision 1 Page 6 of 14 Review of Table 5 identified the Total and Divisional LOSP Initiators are also dominant LERF contributors. No changes to the existing compensatory actions listed in Section D are recommended as these have been deemed adequate to address the LOSP risk contributors.

Evaluation of Contributors The dominant risk contributors found in these increased initiators and in the cutsets containing a failed Division 2 RHR NW MDCT Fan are loss of Division 1 power or Division 1 equipment that leads to a loss of the Primary Containment and subsequent core damage or large early release. The compensatory actions listed in Section D have been deemed adequate to address these risk contributors.

D. Compensatory Measures In accordance with MMR12 Equipment Out of Service Risk Management [3], the plant is currently in a LOW risk status and will remain in this category for the NOED period. The following equipment protections will be in effect in accordance with MOP05-100 Protected Equipment [4] and ODE-20, Protected Equipment, [5] until the Division 2 RHRSW NW MDCT Fan is restored:

1. Elective maintenance will not be performed on the following Division 1 Systems:

Emergency Equipment Cooling Water (EECW)

Emergency Equipment Service Water (EESW)

Ultimate Heat Sink (UHS)

Switchgear Emergency Diesel Generators (EDGs)

Reactor Core Isolation Cooling (RCIC)

Core Spray (CS)

Residual Heat Removal (RHR)

Standby Gas Treatment System (SGTS)

Control Center Heating, Ventilation, and Air Conditioning (CCHVAC)

Combustion Turbine Generator (CTG) 11-13 Offsite Power

2. Elective maintenance will not be performed on the following non-divisional systems:

Standby Feedwater (SBFW)

Hardened Containment Vent FLEX

3. Restricted access to all previously stated systems

4. Signage defining systems under protection both within and when entering protected area Further, mitigating actions are in place to prevent mayflies from impacting onsite/offsite power sources.

All offsite power sources are currently operable and Offsite power is being supplied to both the 120 kV and 345 kV switchyards from the transmission network by five transmission lines. Throughout the requested enforcement discretion period, access to the switchyards will be controlled by the Main Control Room and will be restricted to only essential work, with no elective maintenance being performed. Shift Manager approval will be required to access the switchyards.

3 CTG 11-1 (R1100S069) is credited for Black-Start Capability.

TE-E11-23-048 Revision 1 Page 7 of 14 During the morning shiftly Midcontinent Independent System Operator (MISO) communications, Operations will verify no work affecting the 120kV or 345kV switchyards occurs. Weather conditions will be verified to be acceptable prior to authorizing work. Actions will be taken IAW MOP01-200, Severe Weather Guidelines, [6] in response to advanced notification of possible severe weather conditions.

Control Room staff will utilize shiftly turnover meetings to discuss plant activities that may increase the likelihood of causing a Loss of Offsite Power or Internal Flooding Event. Operations will verify twice per shift that no flooding evidence exists on the Reactor Building 3rd Floor nor the Division 1 Switchgear Room. Further, the following PRA credited flood barriers will be verified closed every 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />s:

NW Torus Room SW Torus Room SE Torus Room NE Torus Room T-Room Watertight Door HPCI Room Watertight Door Division 2 Switchgear Room Double Doors While in the proposed period of enforcement discretion, overall plant risk will be managed by the existing Configuration Risk Management Program (CRMP) [3]. This program evaluates increases in risk posed by potential combinations of equipment out-of-service and potential increases in initiating event frequency and requires that risk management actions be implemented as appropriate for a given plant configuration.

Maintenance and testing during the allowed outage time extension will be rescheduled for Fermi 2 as warranted to minimize aggregate risk. This will specifically include work performed on safety significant systems and their applicable support systems. Emergent Conditions will be evaluated by operations under the CRMP. No quantitative credit was taken in the evaluation for the implementation of the compensatory measures.

E. Extent of Condition Each divisional half of the Residual Heat Removal Service Water (RHRSW) Reservoir has one Mechanical Draft Cooling Tower. Each MDCT has two fans that force air through the cooling tower to aid in heat rejection. Each MDCT is designed to cool one Division of the Plant heat load. To address a Common Cause Failure (CCF) on the Division 2 RHRSW NW MDCT Fan, the probability of the CCF basic events that include E1156C001D were increased to the respective alpha factor (a k) [7] in accordance with the methodology outlined in the NRC Risk Assessment of Operational Events Handbook [8].

The potential cause of the RHRSW NW MDCT Fan trip due to vibrations is the degraded mounting condition of the gear reducer to its pedestal or degraded grommets on the driveshaft coupling to the gear reducer. Because the other MDCT Fans have the same mounting and grommet configuration, the Common Cause Factors were adjusted as noted in Table 6.

TE-E11-23-048 Revision 1 Page 8 of 14 Table 6: Summary of Common Cause Factors and Alpha Factors Alpha Basic Event Name Description Factor [ak]

Common Cause Group 2 of 4: E1156C001A and FCTSUHSXCC24_4 1.29E-02 E1156C001D Common Cause Group 2 of 4: E1156C001B and FCTSUHS2CC24_2 1.29E-02 E1156C001D Common Cause Group 2 of 4: E1156C001C and FCTSUHSXCC24_2 1.29E-02 E1156C001D Common Cause Group 3 of 4: E1156C001A, FCTSUHSXCC34_2 8.77E-03 E1156C001B, and E1156C001D Common Cause Group 3 of 4: E1156C001A, FCTSUHSXCC34_3 8.77E-03 E1156C001C, and E1156C001D Common Cause Group 3 of 4: E1156C001B, FCTSUHSXCC34_4 8.77E-03 E1156C001C, and E1156C001D Common Cause Group 4 of 4: E1156C001A, FCTSUHSXCC44_1 5.46E-03 E1156C001B, E1156C001C, and E1156C001D F. External Event Risk To fully characterize the risk presented by this condition, an assessment should be performed on external event factors that could impact safety during the period of enforcement discretion. Fermi 2 has developed an Other External Hazards (OEH) Screening Report to determine the applicability of various external events to Fermi 2. The result of the screening report was that only internal flooding, internal fire and seismic hazards require detailed PRAs. Internal flooding is already included in the Fermi 2 internal events model.

A peer review of the Fermi 2 OEH Screening Report was conducted in May 2014 by industry peers under the auspices of the Boiling Water Reactor Owners Group (BWROG). The peer review report shows details of the Facts and Observations (F&Os) that were written as a result of this assessment. The report found that all supporting requirements meet Capability Category I/II/III of the ASME/ANS standard. All findings from this peer review have subsequently been closed. As only fire and seismic hazards were identified as necessary, no further external hazards need to be evaluated for this application.

TE-E11-23-048 Revision 1 Page 9 of 14 Discussion of Risk Insights from Internal Fires Unscreened Fire Areas From the Fermi 2 Individual Plant Examination for External Events (IPEEE) [9], which employed a FIVE methodology, six unscreened fire areas were shown to be risk significant. These are shown below in a reproduction of Table 4-14 of the IPEEE.

Unscreened Fire Areas Fire Area Description RB06 Reactor Building 2nd Floor 03AB Relay Room 04ABN Division 1 Switchgear Room 09AB Control Room 11ABE Div. 1 Portion Miscellaneous Room 12AB Division 2 Switchgear Room Each of the compartments is discussed below in the context of the current plant configuration to develop risk-informed insights for fire hazards. The goal of this analysis is to evaluate fires that preferentially impact Division 1 RHR decay heat removal and rely upon the Division 2 counterparts for achieving safe shutdown.

RB06:

From Section 4.3.1.4.5 of the IPEEE, dominant fires in this area lead to core damage due to their impact on bus 72CF, which impacts both divisions of LPCI. Core damage sequences for these fires are dominated by random failure of the torus cooling injection valves. In addition, some scenarios in this fire area can result in failure of Division 1 RHR and the Torus Hardened Vent. As these dominant fires can affect the ability of Division 1 RHR to remove decay heat, fire risk management actions will be implemented in this area.

03AB:

Section 4.3.1.4.1 of the IPEEE describes the dominant core damage scenarios for fires in the relay room.

The dominant fires in this area cause depressurization and loss of one division of RHR for heat removal.

In addition, some scenarios in this fire area can result in failure of Division 1 RHR and the Torus Hardened Vent. As these dominant fires can affect the ability of Division 1 RHR to remove decay heat, fire risk management actions will be implemented in this area.

04AB:

Section 4.3.1.4.2 of the IPEEE states that dominant core damage contributors in the Division 1 Switchgear Room involve severe degradation of Division 1 decay heat removal capability. In addition, some scenarios in this fire area can result in failure of Division 1 RHR and the Torus Hardened Vent. As these dominant fires can affect the ability of Division 1 RHR to remove decay heat, fire risk management actions will be implemented in this area.

09AB:

From Section 4.3.1.4.3 of the IPEEE, the most severe fire in the control room is a fire in panel H11P602, which defeats all Division 2 ESF systems and results in core damage due to random failure of standby feedwater and Division 1 low pressure injection systems. Dominant fires in this zone do not impact the ability to remove decay heat using Division 1 RHR, so no fire risk management actions are required for this area.

TE-E11-23-048 Revision 1 Page 10 of 14 11ABE:

The most severe fires mentioned, from Section 4.3.1.4.4 of the IPEEE, in the DC MCC area are those that affect Division 1 DC and would rely upon Division 2 systems, including for decay heat removal. As these dominant fires can affect the ability of Division 1 RHR to remove decay heat, fire risk management actions will be implemented in this area.

12AB:

This fire area is the divisional opposite of 04ABN. Because fires in this area defeat Division 2 systems, this area was considered for fire risk management actions. Dominant fires in this zone do not impact the ability to remove decay heat using Division 1 decay heat removal, so no fire risk management actions are required for this area.

Fire Risk Management Actions For compartments RB06, 03AB, 04AB, and 11ABE the following risk management actions will be taken during the period of requested enforcement discretion. These actions reduce the probability of a consequential fire in the risk significant areas of the plant.

Minimize transient combustibles Prohibit hot work or limit with adequate compensatory measures per ODE-20 Confirm availability of detection and suppression systems Confirm fire barriers intact Inspect area for fire source degradation Minimize electrical switching at panels as applicable or establish compensatory measures per ODE-20 Discussion of Risk Insights from Seismic Hazards Seismic events are those that are likely to lead to core damage by causing a loss of offsite power. As such, existing measures to protect Division 1 EDGs and Division 1 RHR are considered prudent measures to reduce the risk of seismic events during the period of proposed enforcement discretion.

G. Conclusion The risk associated with operating the plant with the Division 2 RHRSW NW MDCT Fan (E1156C001D) unavailable in support of repairs for a period of up to 2.71 days for enforcement discretion was found to meet the thresholds of NRC EM APP F. To augment this evaluation, risk will be minimized during the proposed period of enforcement discretion by implementation of the compensatory measures described in this evaluation. These compensatory measures will be in effect prior to entry into the period of the proposed enforcement discretion.

TE-E11-23-048 Revision 1 Page 11 of 14 H. References

[1] NRC Enforcement Manual Appendix F, "Notices of Enforcement Discretion", 2019.

[2] TMSA-21-0001, Documentation of the Release of PSA Model FermiV12", 2021.

[3] MMR12 "Equipment Out of Service Risk Management", Revision 20A, 2019.

[4] MOP05-100 "Protected Equipment" Revision 2C, 2018.

[5] ODE-20, "Protected Equipment" Revision 29, 2023.

[6] MOP01-200, "Severe Weather Guidelines" Revision 4, 2021.

[7] EF2-PRA-010, "Fermi 2 Nuclear Power Station PRA Component Data Notebook, VOL 2", 2021.

[8] NRC Risk Assessment of Operational Events Handbook, VOL I - Internal Events, Revision 2.01, 2017.

[9] TMSA-10-0010, "Fermi 2 Individual Plant Examination for External Events (IPEEE)", 2010.

Kasi Rhodes From: Kasi Rhodes Sent: Friday, July 21, 2023 11:57 AM To: Kasi Rhodes Cc: Michael Lake; Mickey Koenemann

Subject:

TE-E11-23-048 Rev 1 Preparer Signature This email serves as my approval to sign the following documents electronically as PREPARER for the following document and should be attached for vaulting purposes:

DSN Revision DTC Date TE-E11-23-048 1 TDEVAL 07/21/2023 I have verified my qualification to PSA-01 and PSA-09 as required per MMR12 for this task prior to sending this email.

Thank you, KASI RHODES M R UL E & P S A E NG I NE E R Enrico Fermi Atomic Power Plant l Newport, MI 734.586.4165 l kassandra.rhodes@dteenergy.com This communication may contain privileged or confidential information protected by legal rules. It is solely for the use of the intended recipient named above. Any review, dissemination, distribution, forwarding, or copying of this communication by someone other than the intended recipient, or the employee responsible for delivering this communication to the intended recipient, is prohibited. If you have received this communication in error, please immediately notify us by phone or reply to the sender via email, then destroy the original message. Thank you.

1

Kasi Rhodes From: Mickey Koenemann Sent: Friday, July 21, 2023 12:07 PM To: Kasi Rhodes

Subject:

TE-E11-23-048, Rev 1 Review Signature This email serves as my approval to sign the following documents electronically as REVIEWER for the following document and should be attached for vaulting purposes:

DSN Revision DTC Date TE-E11-23-048 1 TDEVAL 07/21/2023 I have verified my qualification to PSA-01 and PSA-09 as required for this task prior to sending this email.

Mickey Koenemann PSA Technical Expert - Fermi 2 734-586-1885 Michael.koenemann@dteenergy.com 1

Kasi Rhodes From: Michael Lake Sent: Friday, July 21, 2023 12:12 PM To: Kasi Rhodes; Mickey Koenemann

Subject:

TE-E11-23-048 Rev 1 Approver Signature This email serves as my approval to sign the following documents electronically as APPROVER for the following document and should be attached for vaulting purposes:

DSN Revision DTC Date TE-E11-23-048 1 TDEVAL 07/21/2023 1