IR 05000341/2022010
| ML23163A172 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 06/21/2023 |
| From: | Karla Stoedter NRC/RGN-III/DORS |
| To: | Peter Dietrich Detroit Edison, Co |
| Shared Package | |
| ML23160A152 | List: |
| References | |
| IR 2022010 | |
| Download: ML23163A172 (1) | |
Text
SUBJECT:
REISSUE - FERMI POWER PLANT, UNIT 2 - DESIGN BASIS ASSURANCE INSPECTION (TEAMS) INSPECTION REPORT 05000341/2022010
Dear Peter Dietrich:
On September 30, 2022, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Fermi Power Plant, Unit 2 and discussed the results of this inspection with Eric Olson, Site Vice President and other members of your staff. On November 9, 2022, we issued inspection report 05000341/2022010 (ML22313A103) to document the result of the inspection. The inspection report is being re-issued to document the results of an independent review of an operability issue regarding the emergency diesel generators and to revise a previously documented non-cited violation (NCV).
Two findings of very low safety significance (Green) are documented in this report. One of these findings involved a violation of NRC requirements. We are treating this violation as an NCV consistent with Section 2.3.2 of the Enforcement Policy.
If you contest the violation or the significance or severity of the violation documented in this inspection report, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission, ATTN:
Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region III; the Director, Office of Enforcement; and the NRC Resident Inspector at Fermi Power Plant, Unit 2.
If you disagree with a cross-cutting aspect assignment or a finding not associated with a regulatory requirement in this report, you should provide a response within 30 days of the date of this inspection report, with the basis for your disagreement, to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region III; and the NRC Resident Inspector at Fermi Power Plant, Unit 2.
June 21, 2023 This letter, its enclosure, and your response (if any) will be made available for public inspection and copying at http://www.nrc.gov/reading-rm/adams.html and at the NRC Public Document Room in accordance with Title 10 of the Code of Federal Regulations 2.390, Public Inspections, Exemptions, Requests for Withholding.
Sincerely, Karla K. Stoedter, Chief Engineering Branch 1 Division of Operating Reactor Safety Docket No. 05000341 License No. NPF-43
Enclosure:
As stated
Inspection Report
Docket Number:
05000341
License Number:
Report Number:
Enterprise Identifier:
I-2022-010-0048
Licensee:
DTE Electric Company
Facility:
Fermi Power Plant, Unit 2
Location:
Newport, MI
Inspection Dates:
August 08, 2022 to September 30, 2022
Inspectors:
C. Baron, Mechanical Contractor
J. Benjamin, Branch Chief
B. Daley, Senior Reactor Inspector
M. Domke, Reactor Inspector
K. Fay, Reactor Inspector
B. Jose, Senior Reactor Inspector
E. Sanchez Santiago, Senior Project Engineer
Approved By:
Karla K. Stoedter, Chief
Engineering Branch 1
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a design basis assurance inspection (teams) inspection at Fermi Power Plant, Unit 2, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.
List of Findings and Violations
Failure to Ensure Operating Experience (OPEX) Review of NRC Information Notice 2017-06 Was Completed with Appropriate Rigor Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green FIN 05000341/2022010-01 Open/Closed
[H.14] -
Conservative Bias 71111.21M The inspectors identified a finding of very low safety significance (Green), that was not associated with a violation of NRC requirements, for the licensees failure to perform a review of OPEX with appropriate rigor to ensure risk to the station was minimized or eliminated as specified in Fermi 2 Licensing/Safety Engineering Conduct Manual MLS04, Operating Experience Program, Revision 36. Specifically, the licensee failed to perform a thorough review for NRC Information Notice (IN) 2017-06, "Battery and Battery Charger Short-Circuit Current Contributions to a fault on the Direct Current (DC) Distribution System," with appropriate rigor to ensure the risk to the station from a higher than expected short circuit current contribution from the battery chargers to the DC system was appropriately minimized or eliminated.
Failure to Identify Potential Tripping of Emergency Diesel Generators (EDGs) during Tornado Pressure Transients and Subsequent EDG Inoperability Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000341/2022010-02 Open/Closed None (NPP)71111.21M The inspectors identified a Green finding and associated Non-Cited Violation (NCV) of Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix B, Criterion XVI, Corrective Action, Technical Specifications (TSs) 3.8.1, AC Sources - Operating, and 3.8.2,
AC Sources - Shutdown, due to the failure to identify a condition adverse to quality which resulted in the EDGs being inoperable. Specifically, the licensee failed to identify the EDGs could inadvertently shut down (also known as trip) during a tornado due to the rapid reduction of pressure in the EDG rooms and the actuation of the high crankcase pressure trip. This non-conforming condition, which has existed since initial operation, resulted in the EDGs being unable to meet the specified safety function of remaining operable during and after a design basis tornado event. The licensee had an opportunity to identify this condition in 2016 but failed to critically review information provided by the EDG supplier.
Additional Tracking Items
None.
INSPECTION SCOPES
Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.
REACTOR SAFETY
===71111.21M - Design Bases Assurance (DBAI) Inspection The inspectors evaluated the following components and listed applicable attributes, permanent modifications, and operating experience:
Design Review - Risk-Significant/Low Design Margin Components (IP Section 02.02)
=
- (1) Bus 72F and Bus Regulators, R14005021 and R14005021B
Updated Final Safety Analysis Report, Technical Specifications, Technical Requirements Manual reviews for license basis requirements
Minimum and maximum short circuit current available at the bus
Minimum voltage available during degraded voltage conditions
Minimum voltage available at the loads fed by the bus
Load breakers coordination with the upstream supply breaker
Short circuit carrying capacity of the supply breaker compared to the available fault current
Testing or preventive maintenance on the bus and the regulators
Functions of the regulators, how they are monitored, calibrations if any, and their frequency
Vendor recommended maintenance/regulator replacement frequency
Review bus and regulator related condition reports
- (2) Reactor Core Isolation Cooling Pump Discharge Valve, E5150F012
Updated Final Safety Analysis Report, Technical Specifications, Technical Requirements Manual reviews for license basis requirements
Field walkdown of component E5150F012
Testing and Inspection procedure reviews including acceptance criteria and recent results for leak rate, in-service testing, and leakage
Translation of vendor specifications to associated procedures
System health (failures, operability evaluations, corrective action review documents)
Condition Report reviews related to component E5150F012
Licensing changes to reclassify valve from a pressure isolation requirements due to undersized actuator
- (3) Emergency Diesel Generator (EDG) 13
Updated Final Safety Analysis Report, Technical Specifications, Technical Requirements Manual reviews for license basis requirements
Evaluation of internal/external flood protection
Evaluation of potential seismic hazards
Evaluation of expendables stored on site
Susceptibility of emergency diesel generator heating and ventilation system to tornado depressurization transient
EDG area ventilation system design
Air start check valve testing and acceptance criteria basis
Evaluation of EDG frequency and voltage variations
EDG heat exchanger cooling water flow requirements
Fuel oil consumption
Walkdowns to evaluate material condition
Engine trip parameters
Evaluation of operating procedures to manually load/shed loads after accident
Service condition of components
- (4) Division 1 and 2 Battery Chargers
Updated Final Safety Analysis Report, Technical Specifications, Technical Requirements Manual reviews for license basis requirements
Translation of vendor specifications to associated procedures
System health (failures, operability evaluations, corrective action review documents)
Electrical design calculations for:
o Sizing o
Current limiting setting o
Duty cycle o
Short circuit o
Voltage drop o
Circuit coordination o
Fuse sizing and ratings
Design Review - Large Early Release Frequency (LERFs) (IP Section 02.02) (1 Sample)
- (1) Residual Heat Removal Service Water Pump A, E115C001A
Updated Final Safety Analysis Report, Technical Specifications, Technical Requirements Manual reviews for license basis requirements
Field walkdown
System health (failures, operability evaluations, corrective action review documents)
Review of condition reports related to the pump and appurtenances
Mechanical design calculations including flow capacity, runout flow, minimum flow, required submergence, and flow balance
Testing and Inspection procedures, acceptance criteria and recent results for quarterly and comprehensive in-service testing surveillances
Modification reviews including pump replacement work order for E115C001A in 2020 Maintenance effectiveness including Maintenance Rule reviews and Maintenance procedure reviews
Translation of vendor specifications to associated procedures
Operating procedure reviews during normal, abnormal or accident operations
Modification Review - Permanent Mods (IP Section 02.03) (5 Samples)
(1)
70039; Replacement of Various Circuit Breakers and Power Shields (2)80065; Permanent Plant Mod to Ensure that the 4160 ESF Bus Degraded Voltage Load Shed Logic is Inhibited (3)70015; E1150F068B-004 Replacement of Lower Stem Bushing for RHR Division 2 Heat Exchanger Service Water Outlet Isolation Motor Operated Valve (4)80127; ECCS [Emergency Core Cooling System] Pump CST [Condensate Storage Tank] Vortex Suppression Device (5)37362; Residual Heat Removal and Core Spray Strong Pump/Weak Pump Interaction Review of Operating Experience Issues (IP Section 02.06)
- (1) OE-2020-0175; Grid Disturbance Causes Loss of Spent Fuel Pool Cooling Pump
- (2) NRC Information Notice 2017-06, Battery and Battery Charger Short-Circuit Contribution to a Fault on DC System
INSPECTION RESULTS
Failure to Ensure Operating Experience (OPEX) Review of NRC Information Notice 2017-06 was Completed with Appropriate Rigor Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green FIN 05000341/2022010-01 Open/Closed
[H.14] -
Conservative Bias 71111.21M The inspectors identified a finding of very low safety significance (Green), that was not associated with a violation of NRC requirements, for the licensees failure to perform a review of OPEX with appropriate rigor to ensure risk to the station was minimized or eliminated as specified in Fermi 2 Licensing/Safety Engineering Conduct Manual MLS04, Operating Experience Program, Revision 36. Specifically, the licensee failed to perform a thorough review for NRC Information Notice (IN) 2017-06, "Battery and Battery Charger Short-Circuit Current Contributions to a fault on the Direct Current (DC) Distribution System," with appropriate rigor to ensure the risk to the station from a higher than expected short circuit current contribution from the battery chargers to the DC system was appropriately minimized or eliminated.
Description:
IN 2017-06 discussed test results published in NUREG/CR-7229 by Brookhaven National Laboratories on different types of battery chargers under short circuit conditions. The test results showed short circuit current contribution from a Silicon Controlled Rectifier (SCR) type battery charger could be as high as 7 to 10 times the charger's full load rating during the first 100 milliseconds. Fermi 2 has 100 ampere SCR type battery chargers and therefore, the short circuit current could contribute approximately 700 to 1000 amperes if a fault occurred in the DC system. NRC inspectors reviewed the licensees response to the IN titled "OPEX review of NRC IN 2017-06." During this review, the inspectors noted the original review performed by the licensee under Corrective Action Report Document (CARD) 18-21882 was questioned by the 2019 Design Basis Assurance Inspection (DBAI) team for its adequacy.
Subsequently, the licensee revised the OPEX review under CARDs 19-23579 and 19-23651.
During the review of CARD 19-23651, the 2022 DBAI team identified the licensee had not properly calculated the maximum short circuit current. Specifically, the licensee had only looked at the maximum short circuit current at the non-safety-related volt meters closest to the batteries and chargers. Because of the cables feeding the volt meters were number 12 American Wire Gage, the maximum fault current calculated was incorrectly determined to be less than 10,000 amperes. Since the DC distribution panel busses were rated for 10,000 amperes, the licensee concluded that higher fault current contribution from the battery chargers would only result in loss of one DC division and no additional damage would occur.
However, as a conservative measure, the licensee replaced the DC distribution panel feeder fuses with 20,000 ampere interrupting capacity. The inspectors noted the licensees conclusion may not be appropriate as they had neither evaluated the maximum fault current at the DC busses nor did they verify interrupting ratings of the battery charger internal fuses and the charger output breaker.
Based on the concerns raised by the 2022 DBAI team, the licensee performed additional analysis which resulted in fault currents exceeding 10,000 amperes at the Division 2 DC Busses. The licensee initiated CARDs 22-2900, "2022 NRC DBAI Inspection: NRC identified technical error in Engineering Design Package (EDP) 70287, Revision 0," and 22-29053 "2022 NRC DBAI Inspection NRC Identified: Information Notice 17-06 not appropriately evaluated/resolved." The licensee also contacted Sargent and Lundy Engineers to review the Fermi 2 DC short circuit calculations to see if a more realistic loading pattern could be used in the calculation. Sargent and Lundy Engineers removed certain DC loads to mimic a more realistic loading scenario under various conditions and revised the DC load model in the Electrical Transient Analyzer Program (ETAP) which resulted in less than 10,000 ampere short circuit current at the Fermi 2 Division 2 DC Busses. As a long term solution, the licensee plans to replace the Division 2 DC Busses with more than 10,000 ampere fault current carrying capacity. The inspectors did not identify any other technical concerns. The inspectors reviewed the battery chargers internal fuse characteristics and coordination with the downstream protective devices and did not identify any concerns.
Section 4.4.4 of Fermi 2 Licensing/Safety Engineering Conduct Manual MLS04, Operating Experience Program, Revision 36, stated, "Complete CARD evaluations with appropriate rigor to ensure risk to the station is minimized or eliminated." The inspectors determined the licensee's initial and subsequent OPEX evaluations for IN 2017-006 did not meet the licensee's standard for OPEX review stated in MLS04, Section 4.4.4 because the evaluation was not completed with appropriate rigor to determine the short circuit current contribution was exceeded 10,000 amperes and impacted the operation of the Division 2 DC busses. The licensees failure to perform the OPEX reviews within CARDs 18-21882, 19-23579, and 19-23651 with appropriate rigor to minimize or eliminate risk to the station was contrary to the Fermi 2 Procedure MLS04 and was a performance deficiency. No violations of NRC requirements were identified since this procedure was not safety-related and therefore, not subject to Title 10 of the Code of Federal Regulations Part 50 Appendix B requirements.
Corrective Actions: The licensee revised the OPEX evaluation for IN 2017-06 and concluded the larger short circuit current contribution from the charger did not exceed the interrupting ratings of equipment/isolation devices.
Corrective Action References: CARD 22-29053; 2022 NRC DBAI Inspection NRC Identified:
Information Notice 17-06 not Appropriately Evaluated/Resolved.
Performance Assessment:
Performance Deficiency: The inspectors determined the licensees failure to perform a rigorous OPEX evaluation for IN 2017-06 which minimized or eliminated risk to the station was contrary to Fermi 2 Procedure MLS04, Operating Experience Program. Specifically, the licensee failed to appropriately calculate the short circuit current expected and determine the impact on the Division 2 DC busses.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Design Control attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the failure to perform a rigorous OPEX evaluation for NRC IN 2017-06 resulted in a condition where there was a reasonable doubt that equipment/isolation devices were able to withstand the larger short circuit conditions provided by the chargers as described in the IN.
Significance: The inspectors assessed the significance of the finding using Inspection Manual Chapter 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. Specifically, the finding screened as very low safety significance (Green) because the inspectors answered 'yes' to the question: "If the finding deficiency affecting the design or qualification of a mitigating SSC, does the SSC maintain its operability or PRA functionality?
Cross-Cutting Aspect: H.14 - Conservative Bias: Individuals use decision making-practices that emphasize prudent choices over those that are simply allowable. A proposed action is determined to be safe in order to proceed, rather than unsafe in order to stop. Specifically, the licensee's initial and subsequent evaluations for IN 2017-06 failed to evaluate the effect of the larger short circuit current contribution from the charger on the interrupting rating of the equipment/isolation devices. Instead, the licensee only verified that the short circuit current as specified in the revised calculation did not exceed the plant equipment/isolation devices interrupting rating.
Enforcement:
Inspectors did not identify a violation of regulatory requirements associated with this finding.
Failure to Identify Potential Tripping of Emergency Diesel Generators (EDGs) during Tornado Pressure Transients and Subsequent EDG Inoperability Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000341/2022010-02 Open/Closed None (NPP)71111.21M The inspectors identified a Green finding and associated Non-Cited Violation (NCV) of Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix B, Criterion XVI, Corrective Action, Technical Specifications (TSs) 3.8.1, AC Sources - Operating, and 3.8.2, AC Sources - Shutdown, due to the failure to identify a condition adverse to quality which resulted in the EDGs being inoperable. Specifically, the licensee failed to identify the EDGs could inadvertently shut down (also known as trip) during a tornado due to the rapid reduction of pressure in the EDG rooms and the actuation of the high crankcase pressure trip. This non-conforming condition, which has existed since initial operation, resulted in the EDGs being unable to meet the specified safety function of remaining operable during and after a design basis tornado event. The licensee had an opportunity to identify this condition in 2016 but failed to critically review information provided by the EDG supplier.
Description:
The inspectors reviewed the design of the EDGs, including their automatic trip features. The inspectors noted the high crankcase pressure trip (two out of three logic for each EDG) was considered essential and would not be bypassed during an emergency EDG start in the event of an accident or a loss of offsite power (LOOP). Because the high crankcase pressure trip instruments measure the pressure difference between the diesel engine crankcases and the EDG rooms, the inspectors questioned if the EDGs could be subject to an inadvertent trip if the room pressures were suddenly reduced due to a postulated tornado event.
Updated Final Safety Analysis Report (UFSAR) Section 8.3.1.1.8.2 stated, "the RHR [residual heat removal] complex structure serves to contain, protect, house, and support the equipment of the EDG system and protect it from the outdoor environment." Section 8.3.1.1.8.2.i stated, "the EDG system is designed to be operable during and after a design-basis tornado that has the following characteristics Differential pressure between inside and outside of fully enclosed areas -3 lb/sq in. All building structures housing equipment necessary for safe shutdown are designed to withstand a tornado-induced depressurization rate of 1 lb/sq. in/sec for 3 seconds."
The inspectors questioned if the EDG rooms in the RHR complex were considered to be fully enclosed areas and if the tornado-induced depressurization rate of those rooms had been previously analyzed to determine if the EDGs could inadvertently trip. In response, the licensee stated an evaluation had been performed in 2016 based on industry operating experience. Specifically, Corrective Action Review Document (CARD) 16-29153 had been initiated on November 14, 2016, to investigate the potential impact of a tornado on the EDGs.
This investigation was a result of a similar concern at another facility where high crankcase pressure switches, as originally supplied by the diesel generator vendor, which are susceptible to actuation due to pressure differentials during a tornado event." This CARD concluded there was no design deficiency present in the Fermi EDGs and no engineered/installed modifications were required. This conclusion was based on input from the EDG supplier, Fairbanks-Morse Engine.
The licensee also provided correspondence from the EDG supplier dated November 17, 2016, which explained why the specific concern addressed in CARD 16-29153 was not applicable to Fermi. However, this correspondence also addressed the potential of a trip when an EDG was already operating. This portion of the correspondence was based on an unsubstantiated assumption. Specifically, it stated, the crankcase pressure switches are within the engine room (the engine space) and are monitoring the differential between the pressure in the room and the pressure (vacuum) in the crankcase. Even with the engine in operation, the pressure outside of the building should not have an effect on the operation of these pressure switches. And, in fact, because the outlet of the ejector is in the exhaust system (subject to the pressure outside the building), the lower pressure created by the tornado would have a tendency to lower the pressure at the outlet of the ejector which would in turn tend to lower the pressure in the crankcase.
The inspectors questioned whether the assumption implied in the vendors correspondence had been verified by the licensee. Specifically, the inspectors asked if the EDG rooms were isolated from the outside atmospheric pressure and if the EDG crankcase air ejector had sufficient capacity to reduce the crankcase pressure and prevent a trip during a design basis tornado pressure transient event. The licensee stated a quantitative analysis had not been performed and stated the vendor would be contacted for additional information.
After receiving information from the EDG vendor and performing additional investigation, the licensee initiated CARD 22-28738 on August 15, 2022. The CARD stated that it is clear the high crankcase pressure trip would be activated if the EDGs were operating prior to the depressurization of the RHR complex (which houses all four EDGs). The licensee also initiated CARD 22-28763 on August 16, 2022, to evaluate elimination of the EDG crankcase pressure trips or converting the trips to non-essential (bypassed on an emergency start).
As part of CARD 22-28738, the licensee also completed a technical evaluation which concluded that the EDGs tripping on high crankcase pressure due to pressure differentials caused by a design basis tornado was outside of the Fermi licensing basis. However, if the condition were to occur, current plant procedures would be used to manually restart the EDGs and restore torus cooling within 20 minutes. As a result, the licensee concluded the EDGs remained operable and able to perform their required safety functions crediting the manual restart.
The inspectors and an NRC expert on the operability process reviewed the licensees technical evaluation and disagreed with the licensees conclusions regarding this issue being outside of their licensing basis and with the operability of the EDGs prior to crediting the manual restart actions. With regards to the licensing basis, UFSAR Section 8.2.2.2 states that in the case of a major earthquake, tornado, or similar cataclysmic event, the simultaneous loss of all offsite power transmission is improbable. However, should a complete LOOP occur, the engineered safety feature busses will be supplied from the standby EDGs. In addition, UFSAR Section 8.2.2 indicates a LOOP is a credible event during a design basis tornado and is assumed to occur.
The inspectors also reviewed UFSAR Sections 3.3.2 and found the information regarding the depressurization that will occur in the Category 1 RHR Complex. Specifically, Section 3.3.2.2 states, in part, that Category 1 structures have been designed to withstand the effects due to simultaneous action of tornado wind velocity pressures, atmospheric pressure drop, and a single tornado generated missile. Section 3.3.2.3.2.5 goes on state that because of the depressurization that can occur when the very low-pressure area within the funnel of a tornado engulfs a structure, structures housing equipment necessary for safe shutdown must either be designed for the pressurization or be vented. The UFSAR also states that all such structures, except the steam tunnel, are designed for the depressurization. The inspectors found this information to be incorrect because it did not match the plants current design.
Because the EDG rooms within the RHR Complex were designed and constructed with backdraft dampers that directly communicate with the outside environment, it is technically a partially vented building which had not been analyzed by the licensee. Due to the partially vented structure, the EDG rooms can experience the depressurization caused by a design basis tornado and potentially trip due to actuation of the high crankcase pressure circuitry.
This is contrary to UFSAR Section 8.3.1.1.8.2(i) which states, in part, that the EDGs are designed to be operable during and after a design basis tornado. As a result, the inspectors determined the tornado, atmospheric depressurization impacts, and the LOOP were all within the plants licensing and design bases.
With regards to the past and current operability of the EDGs, the inspectors determined the EDGs were currently operable due to the licensee implementing compensatory measures as provided in NRC Inspection Manual Chapter 0326. Specifically, the licensee planned to restart the EDGs and restore torus cooling within 20 minutes (the most time limiting action) if a tornado occurred and the depressurization caused the EDGs to trip on high crankcase pressure. However, the inspectors determined the EDGs were inoperable prior to the compensatory measures being implemented because the EDGs were not able to perform their specified safety function of being operable during and after a design basis tornado (which includes atmospheric depressurization) in accordance with UFSAR Section 8.3.1.1.8.2. In addition, the inability of the EDGs to perform their specified safety function was contrary to the requirements of TS 3.8.1 which requires two EDGs to be operable per division when the reactor is operating in Modes 1, 2, and 3, and TS 3.8.2 which requires to EDGs capable of supplying one division of onsite Class 1E AC electrical power distribution subsystems as required by TS 3.8.8 when the reactor is operating in Modes 4 and 5.
Corrective Actions: CARD 22-28738 was initiated on August 15, 2022, to address this issue.
The licensee also submitted a TS amendment to the NRC to allow the crankcase pressure trip circuitry to be bypassed/inactive when the EDGs receive an emergency start signal.
Corrective Action References: CARDs 22-28664, "Previous Fermi Evaluation of OE in Regard to Potential for Tornado," 22-28738, "IOD Not Supported"
Performance Assessment:
Performance Deficiency: The inspectors determined the failure to identify the potential tripping of the EDGs due to atmospheric pressure transients caused by a design basis tornado and to declare the EDGs inoperable was a performance deficiency. Specifically, the licensee failed to appropriately review operating experience provided to them in 2016 and identify an EDG design deficiency which rendered all four EDGs inoperable.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Design Control attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the atmospheric pressure transient resulting from a design basis tornado could result in the inadvertent tripping of one or more EDGs.
Significance: The inspectors assessed the significance of the finding using Inspection Manual Chapter 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. Specifically, the finding screened as having very low safety significance (Green)because they answered 'yes' to the questions: "If the finding is a deficiency affecting the design or qualification of a mitigating SSC, does the SSC maintain its operability or PRA functionality? The inspectors determined the finding did not cause a loss of PRA functionality.
Cross-Cutting Aspect: Not Present Performance. No cross-cutting aspect was assigned to this finding because the inspectors determined the finding did not reflect present licensee performance. The last update of the crankcase pressure trip setpoints and associated analysis was greater than 3 years ago.
Enforcement:
Violation: 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, states, in part, measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformances are promptly identified and corrected.
TS 3.8.1, AC Sources - Operating, requires two EDGs per division to be operable when the reactor is operating in Modes 1, 2 and 3.
TS 3.8.2, AC Sources - Shutdown, requires two EDGs capable of supplying one division of the onsite Class 1E AC electrical power distribution subsystems required by TS 3.8.8 to be operable when the reactor is operating in Modes 4 and 5.
Contrary to the above, from November 14, 2016, to August 15, 2022, the licensee failed to identify a condition adverse to quality, maintain two EDGs per division as operable when the rector was operating in Modes 1, 2, and 3, and maintain two EDGs capable of supplying one division of the onsite Class 1E AC electrical power distribution subsystems operable when the reactor was operating in Modes 4 and 5. Specifically, the licensee failed to identify the EDGs would trip due to the environmental depressurization caused by a tornado actuating the EDG high crankcase pressure circuitry which rendered the EDGs inoperable. The EDGs tripping during a tornado event is nonconforming with UFSAR Section 8.3.1.1.8.2(i) which states, the EDG system is designed to be operable during and after a design basis tornado that has the following characteristicsDifferential pressure between inside and outside of fully enclosed areas -3 lb/sq in. All building structures housing equipment necessary for safe shutdown are designed to withstand a tornado-induced depressurization rate of 1 lb/sq. in/sec for 3 seconds.
Enforcement Action: This violation is being treated as an NCV, consistent with Section 2.3.2 of the Enforcement Policy.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
On September 30, 2022, the inspectors presented the design basis assurance inspection (teams) inspection results to Eric Olson, Site Vice President and other members of the licensee staff.
On August 26, 2022, the inspectors presented the interim design basis assurance inspection (teams) inspection results to Eric Olson, Site Vice President and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
DC-4953
RHR Complex - Abnormal Operation Damper Lineups
I
DC-5367
Seismic Evaluation of 480V and 4160V Switchgears and
Motor Control Center Breakers
DC-5426
PBOC - High and Moderate Energy Line Break Evaluation
D
DC-5489
Ventilation Air Quality for Diesel Generator Room 11
B
DC-5803
RHRSW Design Basis Requirements
C
DC-5804
DGSW Design Basis Requirements Calculation
F
DC-5866
RHR Complex Evaluation During Site Flood
DC-6249
Service Water Systems Calibrated Hydraulic Model
DC-6309
Design Basis of EDG Fuel Oil and Day Tank Level
Requirements and Setpoints
B
DC-6447
Auxiliary Power System Analysis
F
DC-6480
130/260V DC System Analysis
C
DC-6482
260/130V and 48/24V DC Protective Device Coordination
Calculation
D
Calculations
DC-6774
Fuel Oil Storage Tank Room Minimum Temperature
05-26492
Design Calculation for RHR Complex Depressurization Is
Not Available
11/17/2005
13-24840
EDG Steady State Voltage and Frequency Tech Spec
Ranges
07/10/2013
16-29153
Potential Impact of a Tornado on the Emergency Diesel
Generator
11/14/2016
17-28611
E1150F068B Packing Leak
19-28434
Request Revision to Scope of Outage Work Orders for Bus
Inspections
05/11/2019
20-20568
Request Work Orders for Replacement of 1SA62 and 1SB62
Relays
01/17/2020
20-20637
Tracking CARD for Revision of 24.205.05
06/22/2020
20-22467
IST to Investigate Implementing 2 Pump Testing of the RHR
SW Pumps
03/06/2020
Corrective Action
Documents
20-25227
Shoulder Bolt for Breaker Slide Bracket Stripped - 72F
Position 2B
04/26/2020
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
20-25312
Open Light Socket Failure on 72F Position 3A Breaker
04/28/2020
20-25559
Blown Fuse Found for ESF 2B1-2 Battery Charger
05/05/2020
21-20678
While Racking out 72F Position 5A (Feed to MCC 72F-5A),
the Racking Shutter Would Not Fully Close
01/25/2021
2-28575
Indication Lights were Burnt Out on X4103F130
08/08/2022
2-28576
POS 2A Was Illuminated However It Was Very Dim
08/09/2022
2-28577
X41K003B TCE Flashing Low Battery
08/09/2022
2-28616
22 NRC DBAI Inspection (NRC Identified): 72F Position
5B Racked out with No Tag Nearby
08/10/2022
2-28627
08/10/2022
2-28664
Previous Fermi Evaluation of OE in Regard to Potential for
Tornado
08/11/2022
2-28687
22 DBAI Inspection -Revise Procedure 43.401.515 "RCIC
Pressure Isolation Valve Test"
08/12/2022
2-28738
IOD Not Supported
08/15/2022
2-28763
Evaluate EDG Crankcase Trips
08/16/2022
2-28800
Evaluate EDG Essential Trips
08/17/2022
Corrective Action
Documents
Resulting from
Inspection
2-28801
22 DBAI Inspection: 3071-128-EZ-01 Discrepancy
08/17/2022
260/130V ESS Dual Battery 2PA Distribution - Division 1
Schematic Diagram/Wiring Diagram, 1500 KVA Regulator
Bus 72F R1400S021B
Drawings
M-5734
Emergency Diesel Generator - Functional Operating Sketch
BL
37362
RHR and Core Spray Strong Pump/Weak Pump Interaction
B
70130
Replacement of EDG 14 Fuel Oil Transfer Pump Flowmeter
R30R411D
80122
Update Design Specification 3071-012 -Valves with
Anti-Rotation Key Repair or Upgrade Guidance for Safety
Related Powell Globe Valves
80122.001
Guidance for Safety Related Powell Globe Valve
Anti-Rotation Key Repair or Upgrade
80127
ECCS Pump CST Vortex Suppression Device
C
Engineering
Changes
80142
Replacement of Residual Heat Removal Service Water
(RHRSW) Valve E1150F068A
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Engineering
Evaluations20-001
ISI/NDE-IST Program Evaluation
3071-019
Design Specification - RHR Complex
E
3071-517
Design Specification - RHR Complex
E
DBD R32-00
DC Electrical System Design Basis Document
B
FAI/20-0183
Testing Results CST Vortex Suppressors
Fairbanks Morse
Letter, Response
to FQ13-46
Postulated Tornado Crankcase Pressure Trip
11/17/2016
LCR 20-025-ISI
TSR-38230 Changed the Pressure Isolation Boundary in the
06/29/2020
MES54001
MES54001
EDG 13 Jacket Coolant Hx
MES54001
R30-00
DBD for Emergency Diesel Generator
I
TMPE-02-0342
Evaluation of Increased Ambient Temperature in the RHR
Complex
2/13/2002
TSR-38268
Technical Service Request, Thermal Recombiner System
Abandonment per License Amendment 159
VME 11-2
C&D 3Phase, 6 Pulse SCR Float Chargers
09/05/2007
VME 5-12
Main DC Fuse Cabinets
VME 8-1.1
Vendor Manual Emergency Diesel Generators
VMS22-1.3
Stage Vertical Pump Instruction Manual
X41-03
DBD for Residual Heat Removal Complex Heating and
Ventilating System
B
Miscellaneous
XXX-02
DBD for Design Basis Event Combinations
A
23.307
Emergency Diesel Generator System
135
23.324.01
Operation of CTG 11-1 from CTG 11 Peaker Yard
23.324.05
Supervisory Control-Standby Diesel Operation
24.307.001
Emergency Diesel Generators - Inspection and Preventive
Maintenance
Procedures
24.307.12
Emergency Diesel Generator 13 - ECCS Start Test and
Logic Functional Tests of Bus 65E Breakers
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
24.307.16
Emergency Diesel Generator 13 - Start and Load Test
24.307.37
DGSW, DFOT and Starting Air Operability Test - EDG 14
35.205.011
E1150F068A(B) Globe Valve Maintenance
74.000.18
Chemistry Shift, 72 Hour, and Situation Surveillances
ARP 1D73
RCIC Pump Suction Pressure High/Low
MLS04
Operating Experience Program
37526767
REPLACE FRN-R-400 FUSE PER ERE 45322 AT
R3200SO07A (2A-1 BATT')
10/22/2013
37526832
REPLACE FRN-R-400 FUSE PER ERE 45322 AT
R3200SO07B (2A-2 BATT)
10/22/2013
44152012
Perform 24.206.02 SEC-5.2 RCIC Valve Position Indication
Verification/Manual Initiate
04/16/2017
46456433
Perform 5-Year Verification of Time Critical Actions
08/30/2017
47548189
Final 43.401.515 RCIC Pressure Isolation Valve Leakage
(Test-2:E5150F012)
04/19/2020
48650178
Perform 42.309.04 Div 1 Battery Charger Load Test -2A-2
Only
09/10/2019
48778616
Remove/Reinstall Actuator in Support of WO 48774938
10/02/2017
50084239
Perform 24.206.01 RCIC System Pump Operability and
Valve Test at 1000PSIG
08/17/2019
50917153
Perform 24.206.01 RCIC System Pump Operability and
Valve Test at 1000PSIG
11/08/2019
51561321
Perform 42.309.04 Div 1 Battery Charger Load Test - 2A-1
Only
09/10/2020
51745473
Perform 24.206.01 RCIC System Pump Operability and
Valve Test at 1000PSIG
2/04/2020
2178219
Perform 24.206.02 Sec-5.2 RCIC Valve Position Indication
Verification/Manual Initiate
07/20/2020
2866184
Perform 42.309.04 Div 1 Battery Charger Load Test - 2A1-2
Only
09/08/2020
53719849
Partial 24.205.05, PMT Strokes for E1150F068A
04/17/2019
54453528
Perform 42.309.04 Div 1 Battery Charger Load Test - 2A-2
Only
05/10/2021
Work Orders
54529464
Perform 24.205.05 Partial for E1150F068A
07/16/2019
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
54768485
Perform 24.205.05 Division 1 RHRSW Pump and Valve
Operability
01/13/2021
54796258
Replace RHRSW Pump A
01/16/2020
57114597
Perform 42.309.04 Div 1 Battery Charger Load Test - 2A-1
Only
06/01/2021
242836
Perform 42.309.06 DIV 2 18 Month 130/260 VDC Battery
Check (2B-2 Only)
04/09/2022
243522
Perform 42.309.06 DIV 2 18 Month 130/260 VDC Battery
Check (2B-1 Only)
04/08/2022
276397
Perform 24.205.05 Division 1 RHRSW Pump and Valve
Operability
01/10/2022
59933741
Perform Partial 24.205.05 to Stroke Test E1150F068A
01/12/2021
290633
Perform 24.205.05 Division 1 RHRSW Pump and Valve
Operability
07/12/2022
64803407
Perform 24.205.05 Division 1 RHRSW Pump and Valve
Operability
03/24/2022