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
June 21, 2023
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. 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, Signed by Stoedter, Karla on 06/21/23 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: NPF-43 Report Number: 05000341/2022010 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 Enclosure
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 Report Aspect Section Mitigating Green [H.14] - 71111.21M Systems FIN 05000341/2022010-01 Conservative Open/Closed Bias 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 Report Aspect Section Mitigating Green None (NPP) 71111.21M Systems NCV 05000341/2022010-02 Open/Closed 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) (2 Samples)
- (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 Report Aspect Section Mitigating Green [H.14] - 71111.21M Systems FIN 05000341/2022010-01 Conservative Open/Closed Bias 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 Report Aspect Section Mitigating Green None (NPP) 71111.21M Systems NCV 05000341/2022010-02 Open/Closed 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 Type Designation Description or Title Revision or
Procedure Date
71111.21M Calculations DC-4953 RHR Complex - Abnormal Operation Damper Lineups I
DC-5367 Seismic Evaluation of 480V and 4160V Switchgears and 0
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 0
DC-6249 Service Water Systems Calibrated Hydraulic Model 0
DC-6309 Design Basis of EDG Fuel Oil and Day Tank Level B
Requirements and Setpoints
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 D
Calculation
DC-6774 Fuel Oil Storage Tank Room Minimum Temperature 0
Corrective Action 05-26492 Design Calculation for RHR Complex Depressurization Is 11/17/2005
Documents Not Available
13-24840 EDG Steady State Voltage and Frequency Tech Spec 07/10/2013
Ranges
16-29153 Potential Impact of a Tornado on the Emergency Diesel 11/14/2016
Generator
17-28611 E1150F068B Packing Leak 1
19-28434 Request Revision to Scope of Outage Work Orders for Bus 05/11/2019
Inspections
20-20568 Request Work Orders for Replacement of 1SA62 and 1SB62 01/17/2020
Relays
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 03/06/2020
SW Pumps
20-25227 Shoulder Bolt for Breaker Slide Bracket Stripped - 72F 04/26/2020
Position 2B
Inspection Type Designation Description or Title Revision or
Procedure 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), 01/25/2021
the Racking Shutter Would Not Fully Close
Corrective Action 22-28575 Indication Lights were Burnt Out on X4103F130 08/08/2022
Documents 22-28576 POS 2A Was Illuminated However It Was Very Dim 08/09/2022
Resulting from 22-28577 X41K003B TCE Flashing Low Battery 08/09/2022
Inspection 22-28616 2022 NRC DBAI Inspection (NRC Identified): 72F Position 08/10/2022
5B Racked out with No Tag Nearby
2-28627 EDG DBD Revision 08/10/2022
2-28664 Previous Fermi Evaluation of OE in Regard to Potential for 08/11/2022
Tornado
2-28687 2022 DBAI Inspection -Revise Procedure 43.401.515 "RCIC 08/12/2022
Pressure Isolation Valve Test"
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
2-28801 2022 DBAI Inspection: 3071-128-EZ-01 Discrepancy 08/17/2022
Drawings 6SD721-2530-10 260/130V ESS Dual Battery 2PA Distribution - Division 1 AP
6SD721-2581-14 Schematic Diagram/Wiring Diagram, 1500 KVA Regulator 0
Bus 72F R1400S021B
M-5734 Emergency Diesel Generator - Functional Operating Sketch BL
Engineering 37362 RHR and Core Spray Strong Pump/Weak Pump Interaction B
Changes 70130 Replacement of EDG 14 Fuel Oil Transfer Pump Flowmeter 0
R30R411D
80122 Update Design Specification 3071-012 -Valves with 0
Anti-Rotation Key Repair or Upgrade Guidance for Safety
Related Powell Globe Valves
80122.001 Guidance for Safety Related Powell Globe Valve 0
Anti-Rotation Key Repair or Upgrade
80127 ECCS Pump CST Vortex Suppression Device C
80142 Replacement of Residual Heat Removal Service Water 0
(RHRSW) Valve E1150F068A
Inspection Type Designation Description or Title Revision or
Procedure Date
Engineering 20-001 ISI/NDE-IST Program Evaluation 0
Evaluations
Miscellaneous 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 2
Fairbanks Morse Postulated Tornado Crankcase Pressure Trip 11/17/2016
Letter, Response
to FQ13-46
LCR 20-025-ISI TSR-38230 Changed the Pressure Isolation Boundary in the 06/29/2020
MES54001 EDG 13 Air Coolant HX 0
MES54001 EDG 13 Jacket Coolant Hx 0
R30-00 DBD for Emergency Diesel Generator I
TMPE-02-0342 Evaluation of Increased Ambient Temperature in the RHR 12/13/2002
Complex
TSR-38268 Technical Service Request, Thermal Recombiner System 0
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 0
VME 8-1.1 Vendor Manual Emergency Diesel Generators AC
VMS22-1.3 2 Stage Vertical Pump Instruction Manual 0
X41-03 DBD for Residual Heat Removal Complex Heating and B
Ventilating System
XXX-02 DBD for Design Basis Event Combinations A
Procedures 23.307 Emergency Diesel Generator System 135
23.324.01 Operation of CTG 11-1 from CTG 11 Peaker Yard 4
23.324.05 Supervisory Control- Standby Diesel Operation 3
24.307.001 Emergency Diesel Generators - Inspection and Preventive 86
Maintenance
24.307.12 Emergency Diesel Generator 13 - ECCS Start Test and 48
Logic Functional Tests of Bus 65E Breakers
Inspection Type Designation Description or Title Revision or
Procedure Date
24.307.16 Emergency Diesel Generator 13 - Start and Load Test 61
24.307.37 DGSW, DFOT and Starting Air Operability Test - EDG 14 63
35.205.011 E1150F068A(B) Globe Valve Maintenance 0
74.000.18 Chemistry Shift, 72 Hour, and Situation Surveillances 60
ARP 1D73 RCIC Pump Suction Pressure High/Low 14
MLS04 Operating Experience Program 36
Work Orders 37526767 REPLACE FRN-R-400 FUSE PER ERE 45322 AT 10/22/2013
R3200SO07A (2A-1 BATT')
37526832 REPLACE FRN-R-400 FUSE PER ERE 45322 AT 10/22/2013
R3200SO07B (2A-2 BATT)
44152012 Perform 24.206.02 SEC-5.2 RCIC Valve Position Indication 04/16/2017
Verification/Manual Initiate
46456433 Perform 5-Year Verification of Time Critical Actions 08/30/2017
47548189 Final 43.401.515 RCIC Pressure Isolation Valve Leakage 04/19/2020
(Test-2:E5150F012)
48650178 Perform 42.309.04 Div 1 Battery Charger Load Test -2A-2 09/10/2019
Only
48778616 Remove/Reinstall Actuator in Support of WO 48774938 10/02/2017
50084239 Perform 24.206.01 RCIC System Pump Operability and 08/17/2019
Valve Test at 1000PSIG
50917153 Perform 24.206.01 RCIC System Pump Operability and 11/08/2019
Valve Test at 1000PSIG
51561321 Perform 42.309.04 Div 1 Battery Charger Load Test - 2A-1 09/10/2020
Only
51745473 Perform 24.206.01 RCIC System Pump Operability and 02/04/2020
Valve Test at 1000PSIG
2178219 Perform 24.206.02 Sec-5.2 RCIC Valve Position Indication 07/20/2020
Verification/Manual Initiate
2866184 Perform 42.309.04 Div 1 Battery Charger Load Test - 2A1-2 09/08/2020
Only
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 05/10/2021
Only
54529464 Perform 24.205.05 Partial for E1150F068A 07/16/2019
Inspection Type Designation Description or Title Revision or
Procedure Date
54768485 Perform 24.205.05 Division 1 RHRSW Pump and Valve 01/13/2021
Operability
54796258 Replace RHRSW Pump A 01/16/2020
57114597 Perform 42.309.04 Div 1 Battery Charger Load Test - 2A-1 06/01/2021
Only
242836 Perform 42.309.06 DIV 2 18 Month 130/260 VDC Battery 04/09/2022
Check (2B-2 Only)
243522 Perform 42.309.06 DIV 2 18 Month 130/260 VDC Battery 04/08/2022
Check (2B-1 Only)
276397 Perform 24.205.05 Division 1 RHRSW Pump and Valve 01/10/2022
Operability
59933741 Perform Partial 24.205.05 to Stroke Test E1150F068A 01/12/2021
290633 Perform 24.205.05 Division 1 RHRSW Pump and Valve 07/12/2022
Operability
64803407 Perform 24.205.05 Division 1 RHRSW Pump and Valve 03/24/2022
Operability
16