IR 05000277/2019003

Integrated Inspection Report 05000277/2019003 and 05000278/2019003

ML19296A937
Person / Time
Site:	Peach Bottom
Issue date:	10/22/2019
From:	Jon Greives Reactor Projects Region 1 Branch 4
To:	Bryan Hanson Exelon Generation Co, Exelon Nuclear
Greives J
References
IR 2019003
Download: ML19296A937 (20)

Text

{{#Wiki_filter:ber 22, 2019

SUBJECT:

PEACH BOTTOM ATOMIC POWER STATION, UNITS 2 AND 3 - INTEGRATED INSPECTION REPORT 05000277/2019003 AND 05000278/2019003

Dear Mr. Hanson:

On September 30, 2019, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Peach Bottom Atomic Power Station, Units 2 and 3. On October 4, 2019, the NRC inspectors discussed the results of this inspection with Mr. Matthew Herr, Plant Manager, and other members of your staff. The results of this inspection are documented in the enclosed report.

One finding of very low safety significance (Green) is documented in this report. This finding involved a violation of NRC requirements. We are treating this violation as a non-cited violation (NCV) consistent with Section 2.3.2 of the Enforcement Policy.

If you contest the violation or 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 I; the Director, Office of Enforcement; and the NRC Resident Inspector at Peach Bottom. If you disagree with a cross-cutting aspect assignment 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 I; and the NRC Resident Inspector at Peach Bottom.

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 10 CFR 2.390, Public Inspections, Exemptions, Requests for Withholding.

Sincerely, /RA/ Jonathan E. Greives, Chief Reactor Projects Branch 4 Division of Reactor Projects Docket Nos. 05000277 and 05000278 License Nos. DPR-44 and DPR-56

Enclosure:

As stated

Inspection Report

Docket Numbers: 05000277 and 05000278 License Numbers: DPR-44 and DPR-56 Report Numbers: 05000277/2019003 and 05000278/2019003 Enterprise Identifier: I-2019-003-0038 Licensee: Exelon Generation Company, LLC Facility: Peach Bottom Atomic Power Station, Units 2 and 3 Location: Delta, Pennsylvania Inspection Dates: July 1, 2019 to September 30, 2019 Inspectors: J. Heinly, Senior Resident Inspector P. Boguszewski, Resident Inspector J. DeBoer, Reactor Inspector N. Floyd, Senior Reactor Inspector J. Furia, Senior Health Physicist C. Roettgen, Resident Inspector J. Schoppy, Senior Reactor Inspector B. Smith, Resident Inspector A. Turilin, Reactor Inspector R. Vadella, Project Engineer Approved By: Jonathan E. Greives, Chief Reactor Projects Branch 4 Division of Reactor Projects Enclosure

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Peach Bottom Atomic Power Station, Units 2 and 3 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 E-1 Emergency Diesel Generator Failure Due to a Cable Fault Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [P.3] - 71152 Systems NCV 05000277,05000278/2019003-01 Resolution Open/Closed The inspectors identified a self-revealing, Green non-cited violation (NCV) associated with Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix B, Criterion XVI, Corrective Action, because Exelon did not identify and correct a condition adverse to quality associated with the E-1 emergency diesel generator (EDG). Specifically, Exelon did not implement their cable monitoring program testing on the E-1 diesel and, as a result, did not identify a condition adverse to quality associated with an underground cable prior to its failure during a surveillance test on May 29, 2019, which resulted in the E-1 diesel being declared inoperable.

Additional Tracking Items None.

PLANT STATUS

Unit 2 began the inspection period at full rated thermal power. On September 13, 2019, the unit was reduced to 77 percent thermal power for routine maintenance and was returned to full rated thermal power on September 14, 2019. Unit 2 remained at or near full rated thermal power for the remainder of the inspection period.

Unit 3 began the inspection period at full rated thermal power. On July 22, 2019, the unit was reduced to 70 percent thermal power for routine maintenance and was returned to full rated thermal power on July 23, 2019. On August 6, 2019, the unit began end of cycle coast-down from full rated thermal power and ended the inspection period at 86 percent thermal power.

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 performed plant status activities described in IMC 2515 Appendix D, Plant Status, and conducted routine reviews using IP 71152, Problem Identification and Resolution. 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.

71111.01 - Adverse Weather Protection Seasonal Extreme Weather Sample (IP Section 03.02)

The inspectors evaluated readiness for seasonal extreme weather conditions prior to the onset of seasonal hot temperatures for the following system:

(1) Hot weather alert and 100 degree temperatures on July 18 and July 19, 2019

External Flooding Sample (IP Section 03.04) (1 Sample)

The inspectors evaluated readiness to cope with external flooding for the following area:

(1) Diesel generator building and safety-related pump house on September 19, 2019

71111.04Q - Equipment Alignment Partial Walkdown Sample (IP Section 03.01)

The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:

(1) Unit 2 and Unit 3 'B' emergency cooling tower (ECT) on July 11, 2019

(2) Unit 2 'C' high-pressure service water (HPSW) with E-2 diesel inoperable on August 8, 2019

(3) Unit 3 'B' and 'D' core spray (CS) during Unit 3 'A' and 'C' CS in-service testing on August 27, 2019

71111.05Q - Fire Protection Quarterly Inspection (IP Section 03.01)

The inspectors evaluated fire protection program implementation in the following selected areas:

(1) Diesel generator building on July 24, 2019

(2) Unit 2 high-pressure coolant injection room on August 12, 2019

(3) Unit 2 'B' and 'D' residual heat removal (RHR) pump and heat exchanger room on August 14, 2019

(4) Unit 3 'A' and 'C' CS pump room on August 28, 2019

(5) Control room on September 4 and 5, 2019

71111.06 - Flood Protection Measures Inspection Activities - Internal Flooding (IP Section 02.02a.)

The inspectors evaluated internal flooding mitigation protections in the following:

(1) Torus room on August 22 and 23, 2019

71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance Licensed Operator Performance in the Actual Plant/Main Control Room (IP Section 03.01)

(1) The inspectors observed and evaluated licensed operator performance in the control room during a containment atmosphere dilution surveillance on September 20, 2019.

Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)

(1) The inspectors observed and evaluated a licensed operator requalification training scenario and critique that involved a seismic event, a recirculation loop leak, and an anticipated transient without SCRAM on September 9, 2019.

71111.12 - Maintenance Effectiveness Routine Maintenance Effectiveness Inspection (IP Section 02.01)

The inspectors evaluated the effectiveness of routine maintenance activities associated with the following equipment and/or safety significant functions:

(1) Unit 2 and Unit 3 ECT on August 21, 2019

(2) Unit 2 and Unit 3 EDGs on September 11, 2019

71111.13 - Maintenance Risk Assessments and Emergent Work Control Risk Assessment and Management Sample (IP Section 03.01)

The inspectors evaluated the risk assessments for the following planned and emergent work activities:

(1) Unit 2 and Unit 3 'A' emergency service water (ESW) out of service on July 16, 2019

(2) Unit 2 and Unit 3 E-2 EDG out of service on August 5, 2019

(3) Unit 2 ESW clam control on September 17, 2019

71111.15 - Operability Determinations and Functionality Assessments Operability Determination or Functionality Assessment (IP Section 02.02)

The inspectors evaluated the following operability determinations and functionality assessments:

(1) Unit 2 and Unit 3 E-4 jacket coolant leak on August 19, 2019

(2) Unit 2 and Unit 3 emergency diesel output cables on August 21, 2019

(3) Unit 2 and Unit 3 ESW radiation monitor on August 22, 2019

(4) Unit 2 and Unit 3 SCRAM discharge level switch on August 22, 2019

71111.17T - Evaluations of Changes, Tests, and Experiments Sample Selection (IP Section 02.01)

The inspectors reviewed the following evaluations, screenings, and/or applicability determinations for 10 CFR 50.59 from September 23 through September 26, 2019:

(1) PB-2016-001-E, Compensatory Measures for Operability Evaluation for 2K Automatic Depressurization System (ADS)

(2) PB-2016-006-E, Change in TRMS 3.11 Applicability for RHR Cooler/Fan Units

(3) PB-2016-007-E, Changes to the Analytical Limits in the Neutron Monitoring System

(4) PB-2016-011-E, Level 3 and Level 4 Reactor Pressure Vessel Water Level Analytical Limit Change

(5) PB-2017-005-E, Seismic Monitoring System Replacement

(6) PB-2017-007-E, Revision 7 to NE-164 Specification for Environmental Service Conditions

(7) PB-2018-001-E, Increase Maximum Permissible Containment Purge Valve Closure Time

(8) PB-2019-001-E, Defeat of Reactor Building Closed-Cooling Water (RBCCW) to Drywell Chilled Water Swap

(9) PB-2016-001-S, Relocate DPS-4519

(10) PB-2016-006-S, Relocate Sensing Lines Associated with Shutdown Cooling Pressure Switch PS-2-02-128A(B) and Replace Switch with a Transmitter/Trip Unit Instrument Loop

(11) PB-2016-010-S, Unit 2 CST Cross-Connect Pipe

(12) PB-2016-011-S, Revision to TS Bases 3.3.3-2 Remote Shutdown System

(13) PB-2016-013-S, LPCI Valve Interposing Relay Pickup Voltage Testing Frequency Change

(14) PB-2016-016-S,Emergency Core Cooling System (ECCS) Air Void Acceptance Criteria

(15) PB-2016-026-S, GP-20 Temporarily Defeating ECCS Auto Initiation Signal during Outages

(16) PB-2016-058-S, Replace AO-3-07B-3519 Operator with Hold-Closed Gag

(17) PB-2016-064-S, Remove Single Point Vulnerability in Fuel Pool Cooling and Cleanup System

(18) PB-2017-030-S, Bypassing and Restoring Main Control Room Chiller Trips

(19) PB-2017-036-S, Temporary Defeat of CW System Auto Transfer to RBCCW

(20) PB-2017-052-S, Use RI-0761 (Radwaste Vent Radiation Indicator) to Replace RI-2979B (Vent Stack Wide Range Radiation Indicator)

(21) PB-2018-004-S, Minimum Wall Determinations Using Finite Element Analysis Method

(22) PB-2018-005-S, Revise TS 3.7.1 Bases to Provide Clarity Regarding When HPSW is Considered Operable When Using Cross-Tie Capability

(23) PB-2018-011-S, Defeat of a Main Turbine Trip Signal

(24) PB-2018-017-S, Revise TR 3.1.3 Frequency to 24 Months

(25) PB-2018-018-S, HPSW/ESW Pipe Barrier and Monitoring

(26) PB-2018-035-S, Upgrade Main Control Room Lighting

(27) PB-2018-036-S, Heavy Load Lifts Over Fuel - Procedure Revisions

(28) PB-2018-040-S, Revision 13 of PE-0166 EDG Loading for Cases Defined by 8.5.2 C/L

(29) PB-2019-018-S, High Area Temperature Alarm Setpoint Change

==71111.18 - Plant Modifications Temporary Modifications and/or Permanent Modifications (IP Section 03.01 and/or 03.02) (1 Sample) The inspectors evaluated the following temporary or permanent modification:

(1) Unit 2 and Unit 3 E-1 cable replacement on August 1, 2019

71111.19 - Post-Maintenance Testing Post-Maintenance Test Sample (IP Section 03.01)

[[IP sample::=

=IP 71111.18|count=4}}

The inspectors evaluated the following post-maintenance tests:

(1) Unit 2 and Unit 3 'B' ECT on July 12, 2019

(2) Unit 2 'B' CS level switches on July 23, 2019

(3) Unit 2 and Unit 3 E-1 diesel generator cable replacement on August 2, 2019

(4) Unit 2 and Unit 3 ESW radiation monitor on August 26, 2019

71111.22 - Surveillance Testing The inspectors evaluated the following surveillance test: Surveillance Tests (other) (IP Section 03.01)

(1) Calibration of Unit 2 LT-2804A on September 17, 2019

(2) Unit 2 average power range monitor surveillance test on September 30, 2019

(3) Unit 2 4kV undervoltage relays surveillance test on September 27, 2019

71114.06 - Drill Evaluation Select Emergency Preparedness Drills and/or Training for Observation (IP Section 03.01)

(1) The inspectors observed an emergency preparedness drill that involved a radioactive release outside containment and fuel failure on September 19,

71124.08 - Radioactive Solid Waste Processing and Radioactive Material Handling, Storage, and Transportation Radioactive Material Storage (IP Section 02.01)

The inspectors evaluated radioactive material storage.

(1) The inspectors observed radioactive waste container storage areas and verified the postings and controls and that the licensee had established a process for monitoring the impact of long-term storage of the waste.

Radioactive Waste System Walkdown (IP Section 02.02) (1 Sample) The inspectors evaluated the following radioactive waste processing systems [and processes] during plant walkdowns:

(1) The inspectors walked down: accessible portions of liquid and solid radioactive waste processing systems; abandoned in place radioactive waste processing equipment; and, current methods and procedures for dewatering waste.

Waste Characterization and Classification (IP Section 02.03) (1 Sample) The inspectors evaluated the radioactive waste characterization and classification for the following waste streams:

(1) The inspectors identified radioactive waste streams and reviewed radiochemical sample analysis results to support radioactive waste characterization. The inspectors reviewed the use of scaling factors and calculations to account for difficult-to-measure radionuclides.

Shipment Preparation (IP Section 02.04) (1 Sample)

The inspectors evaluated [and observed] the following radioactive material shipment preparation processes:

(1) The inspectors reviewed the records of shipment packaging, surveying, labeling, marking, placarding, vehicle checks, emergency instructions, disposal manifest, shipping papers provided to the driver, and licensee verification of shipment readiness.

Shipping Records (IP Section 02.05) (1 Sample)

The inspectors evaluated the following non-excepted package shipment records:

(1) PW-18-0002; PW-19-0004; PW-18-0027; PW-18-0025; PW-18-0006

71152 - Problem Identification and Resolution Annual Follow-up of Selected Issues (IP Section 02.03)

The inspectors reviewed the licensees implementation of its corrective action program (CAP) related to the following issue:

(1) Cable monitoring program on September 19,

INSPECTION RESULTS

E-1 Emergency Diesel Generator Failure Due to a Cable Fault Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [P.3] - 71152 Systems NCV 05000277,05000278/2019003-01 Resolution Open/Closed The inspectors identified a self-revealing, Green non-cited violation (NCV) associated with Title 10 of the Code of Federal Regulations (CFR) Part 50, Appendix B, Criterion XVI, Corrective Action, because Exelon did not identify and correct a condition adverse to quality associated with the E-1 emergency diesel generator (EDG). Specifically, Exelon did not implement their cable monitoring program testing on the E-1 diesel and, as a result, did not identify a condition adverse to quality associated with an underground cable prior to its failure during a surveillance test on May 29, 2019, which resulted in the E-1 diesel being declared inoperable.

Description:

Peach Bottom has four EDGs that supply emergency power (4kV) to both Unit 2 and Unit 3. The electricity is transferred from the generator through nine aluminum conductors, underground from the EDG building to the turbine building. The E-1 diesel provides emergency power to the E-11 and E-12 safety busses.

During a monthly surveillance run of the E-1 EDG on May 29, 2019, the engine was running for approximately 30 seconds, unloaded with the field flashed, when it unexpectedly tripped from an overcurrent protection relay. The E-1 diesel was immediately declared inoperable and Exelon commenced troubleshooting. Exelon determined, through cable testing, that the cause of the trip was a faulted B phase cable that connected the generator to the 4kV breaker. Due to parts availability and limiting condition for operation time constraints, Exelon performed a temporary modification to abandon the B phase cables and reduce the number of energized conductors from nine to six. Exelon performed an engineering analysis to conclude that the remaining six conductors had sufficient capacity to support the maximum diesel loading. Exelon restored the diesel to operable on June 2, 2019.

Exelon entered the E-1 cable fault condition into the CAP under issue report (IR) 4256520 and performed a root cause evaluation. The root cause evaluation determined that the direct cause of the failure was degraded cable insulation likely due to the cables being exposed to adverse environmental conditions for an extended period of time. It further concluded that the engineering cable program owners and their managers did not effectively use the CAP to identify and resolve gaps in the cable program prior to the E-1 EDG cable failure.

Specifically, the cable monitoring program, ER-AA-300-150, requires the station to perform tan-delta testing of the EDG cables and at the time of failure, these cables had not yet been tested in accordance with the frequency required by the program. Tan-delta testing is an industry-accepted method of testing the health of insulation for electrical power cables. The station had originally attempted testing of the cables in 2013; however, they were unsuccessful due to perceived interference with the test equipment as documented in IR 1511027. This IR was closed to a work order (WO) that was never performed. Furthermore, in 2016, a self-assessment discovered that the 2013 WO was inappropriately closed out and created IR 2651755; however, no WO was created from this IR. Again, in 2017, Exelon identified that the 2016 WO was not created and created IR 3963696. Under this IR, Exelon created an action tracking assignment to reschedule the cable testing, and this action was rescheduled 16 times until the cable ultimately failed in May 2019.

Corrective Actions: Exelon abandoned the faulted E-1 diesel cables and performed an engineering analysis to support E-1 operability using only six conductors. In addition, Exelon determined through their extent of condition review that the E-2, E-3, and E-4 cables had not been tested. Therefore, Exelon expedited the replacement of cables for all four EDGs and all cables were replaced by August 2019.

Corrective Action References: IR 4252679

Performance Assessment:

Performance Deficiency: The inspectors determined that failing to identify and correct a condition adverse to quality associated with the E-1 EDG through implementation of their cable monitoring program was a performance deficiency that was within Exelons ability to foresee and correct. Specifically, Exelon did not perform cable testing on the E-1 EDG, in accordance with their cable monitoring program, which resulted in the station not identifying the degraded E-1 cable. This resulted in the unexpected cable failure on May 29, 2019, during the E-1 EDG surveillance test and the E-1 EDG being declared inoperable.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Equipment Performance 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 E-1 EDG was unavailable to perform its safety function when it tripped on over-current due to a faulted output cable.

Significance: The inspectors assessed the significance of the finding using Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The inspectors determined that the finding resulted in the actual loss of a function of a single train (E-1 EDG)for longer than its technical specification (TS) allowed outage time and required a detailed risk evaluation.

The senior reactor analyst (SRA) used the guidance in the Risk Assessment Standardization Project (RASP) handbook Volume I, Revision 2.0, section 2.3, to determine an exposure time of 31 days. The E-1 EDG tripped during a startup with a differential and ground alarm while running unloaded after the field was flashed. This trip occurred after the generator came up to proper voltage and frequency after a nominal 30 seconds and was therefore considered to be a failure to start. The RASP guidance states the exposure time should be the time between the last successful functional operation and the failure discovery date, including repair time, when the inception of the failure is unknown. The SRA noted through interviews with plant personnel and a review of data, that there was no known indication of any abnormal conditions during the last successful monthly surveillance run of the E-1 EDG.

Therefore, there was no data indicating that there would have been imminent failure of the machine once it had reached operating steady state voltage and load conditions. However, after that shutdown and thermal cooldown of the associated cables, the next monthly E-1 start and voltage flash resulted in the failure to start condition. Therefore, the SRA determined that a best estimate of exposure time was from the last successful start and run of the EDG until the subsequent failure, including repair time. This period was a nominal 31 days.

A Region I SRA performed a detailed risk evaluation using the Peach Bottom Unit 2 and Unit 3 Standardized Plant Analysis Risk (SPAR) models, with the Unit 2 model being used as a surrogate for external events for Unit 3. The SRA used a modified Unit 2 SPAR model, version 8.50 and Systems Analysis Programs for Hands-On Integrated Reliability Evaluations version 8.20. This model was revised to include FLEX modifications, which the station had developed in response to Order 12-049, "Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," because this affects how the operators respond to an extended loss of alternating current power. The SPAR model determined the total (internal and external events) contribution to the increase in core damage frequency (CDF) to be 3.5E-7/yr for Unit 2. This was determined to bound the impact to Unit 3. The SRA performed a site visit to review and compare Exelons fire model outputs to the SPAR model to determine a best estimate of the external risk contribution for the failure of the E-1 EDG. The SRA noted that the latest Exelon fire model had a slightly higher estimate for external risk in the range of an increase in CDF of 6E-7/yr for Unit 2 and 3E-7/yr for Unit 3. The SRA noted this included sensitivity analysis considerations for increased FLEX equipment failure rates and FLEX operator failure rates above the licensees baseline model.

The SRA used the SPAR model to determine the internal events increase in CDF/yr. The dominant sequences consisted of a grid related loss-of-offsite-power (LOOP), common cause failure of all the EDGs, with the failure to establish the Conowingo tie line setup (station blackout source), failure to recover offsite power and EDGs, and failure of the reactor core isolation cooling pump to run. The internal events increase in CDF/yr for the E-1 fail to start was determined to be 7E-8/yr for the 31-day exposure. The SRA determined the final best estimate total risk increase in CDF using the SPAR model for internal events and Exelons fire risk model output for external events to be 7E-7/yr for Unit 2 and 4E-7/yr for Unit 3 or of very low safety significance (Green). The risk was dominated by the postulated fire events and was noted to be slightly higher for Unit 2 because of the differences in power sources for the divisional batteries and subsequent effect of the E-1 EDG failure having a greater impact on Unit 2.

Exelons risk evaluation revealed that fire events dominated the risk increase of the E-1 failure, similar to what the SPAR model revealed. The dominant risk contributor for Unit 2 was a fire within the E-42 4kV switchgear room. This included electrical high energy arc fault (HEAF) fires involving the 20A18 switchgear and the 00C026DX E-4 diesel generator alternate control panel fires. The highest contributing core damage sequences included the fire scenario initiating event within this room, failure of high-pressure injection long term, and for some initiating events, the normally aligned offsite power feeder breaker spuriously opening resulting in a LOOP to the E-12 4kV switchgear. Other sequences include losing power because the 00A19 (4kV bus duct feeding the safety busses from offsite power) could be damaged by the HEAF or the breaker upstream of 00A19 opens due to damage to its associated differential relay cabling and failure of the opposite offsite power breaker to close due to cable damage. Therefore, because of the nature of the postulated fire, even though offsite power is being delivered to the station and in various cases the 00A19 and 00A20 bus ducts are still delivering 4kV power to other 4kV switchgears, these events are not considered total LOOP events. However, the above scenarios result in failure of the DC power supply to the safety relief valves resulting in the failure to depressurize, with failure of the high-pressure systems and resultant core damage.

The Unit 2 SPAR model was consistent in reflecting the HEAF within the E-42 switchgear room to be a dominant contributor to the conditional increase in CDF due to the E-1 failure.

This sequence consisted of the HEAF event, with failure to align alternate power to battery charger 2AD03, and failure of the E-3 EDG to run resulting in the loss of high-pressure injection with failure to depressurize with no ability to cross tie AC power.

For Unit 3, Exelons fire model determined that a fire within the Unit 3 E-43 4kV switchgear room was a dominant contributor to the conditional increase in CDF/yr. A HEAF results in the loss of offsite power feed to the safety busses with the E-3 EDG in assumed maintenance (loss of all EDGs) and a failure to align FLEX equipment as one of the dominant sequences.

Exelon performed detailed model runs for the effect on the increase on large early release frequency (LERF). The SRA noted that fires dominated the conditional increase in risk with Unit 2 resulting in a CDF increase of 2E-8/yr and Unit 3 a slightly lower 1E-8/yr for the 31-day exposure time. The SRA reviewed a few of the top core damage sequences and considered them to be reasonable. This was a Level 2 methodology analyzing issues such as magnitude and timing of calculated radionuclide releases through level 2 containment event trees. This resulted in a LERF multiplier for both units relative to the CDF sequences of a nominal 5E-2. Therefore the LERF results were consistent with the CDF determinations of a very low safety significance issue (Green).

Cross-Cutting Aspect: P.3 - Resolution: The organization takes effective corrective actions to address issues in a timely manner commensurate with their safety significance.

Specifically, Exelon had documented their cable monitoring program deficiency in the CAP multiple times and did not effectively correct the issue.

Enforcement:

Violation: 10 CFR Part 50, Appendix B, Criterion XVI, "Corrective Action," requires that measures be established to assure that conditions adverse to quality are promptly identified and corrected. Peach Bottom Units 2 and 3 TS 3.8.1 requires all four EDGs to be operable in Mode 1 and, if any one EDG is determined to be inoperable, it shall be returned to an operable status within 14 days or the unit shall be shut down and in Mode 3 within 12 hours.

Contrary to the above, from May 2013 to May 29, 2019, Exelon did not perform cable testing on the EDG output cables as required by their cable monitoring program, and as a result they did not identify degraded output cables associated with the E-1 diesel, which represented a condition adverse to quality. Furthermore, the failure to perform cable testing was repetitively documented in their CAP and adequate corrective actions were not established prior to the E-1 failure. Therefore, Exelon did not identify and correct the condition adverse to quality associated with the cables that led to the E-1 EDG failure on May 29, 2019. Consequently, the E-1 EDG was rendered inoperable prior to May 29, 2019, for a period longer than its TS allowed outage time, and the unit had not been shut down and placed in Mode 3.

Enforcement Action: This violation is being treated as an NCV, consistent with Section 2.3.2 of the Enforcement Policy.

Observation: Cable Monitoring Program PI&R Sample 71152 The NRC inspectors reviewed corrective actions associated with deficiencies in the implementation of Exelon procedure ER-AA-300-150, Cable Condition Monitoring Program.

The cable monitoring program was established to monitor the health of power cables at Peach Bottom through cable testing.

In December 2018, Peach Bottom experienced an unexpected failure of the 1 start-up (SU)bus power cable, and Exelon entered the condition into the CAP under IR 4241082. Exelon performed a cause evaluation and determined that the 1 SU power cables had incorrectly been excluded from testing under the cable monitoring program. Exelon replaced the 1 SU power cables and added the applicable cables to the cable monitoring testing program.

In May 2019, Peach Bottom experienced an unexpected failure of the E-1 EDG output power cable, which rendered the E-1 diesel inoperable. Exelon entered this condition into the CAP under IR 4252679. Exelon performed immediate corrective actions to modify the E-1 EDG and abandon the faulted cable to support returning it back to operable. Exelon determined that an adverse trend existed in the cable monitoring program performance due to the two unexpected cable failures and numerous adverse performance IRs written against the program from site, NOS, and external organizations. Exelon entered the issues into the CAP under IR 4256520 and performed a root cause evaluation. The root cause determined that the E-1 EDG power cables were not tested because predefined work activities were not established through the work management process. The contributing cause identified that engineering cable program owners and their managers did not effectively use the CAP to identify and resolve gaps in the cable monitoring program prior to the E1 EDG power cable failure. Exelon established extensive corrective actions to include replacement of all EDG output power cables, establishing predefined maintenance tasks for cable testing, CAP action closure quality training, and performance of a comprehensive review of all engineering programs.

The inspectors reviewed the root cause evaluation and determined that it adequately identified the root and contributing causes of the E-1 EDG power cable failure and the degraded performance of the cable monitoring program. The inspectors noted that the cable monitoring program experienced a number of program owner turnovers and contained an inadequate level of documentation in the program notebook to support sufficient ownership and oversight of the program. Furthermore, numerous IRs indicated that potential programmatic weaknesses had not been addressed. These IRs were inadequately addressed or inadvertently closed in the CAP and no substantial corrective actions had been completed. The inspectors identified an NCV regarding Exelons failure to perform adequate corrective actions associated with the cable monitoring program which directly resulted in the unexpected E-1 EDG power cable failure. The NCV is documented under section 71152 of this report. The inspectors review concluded that the proposed corrective actions regarding program ownership and CAP action closure quality were adequate to address the root and contributing causes. Furthermore, the inspectors determined that the station took appropriate conservative actions to replace all of the EDG power cables.

EXIT MEETINGS AND DEBRIEFS

The inspectors verified no proprietary information was retained or documented in this report.

On October 4, 2019, the inspectors presented the integrated inspection results to Mr. Matthew Herr, Plant Manager, and other members of the licensee staff.

On September 26, 2019, the inspectors presented the 10 CFR 50.59 inspection results inspection results to Mr. Pat Navin, Site Vice President, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or Procedure Date 71111.01 Miscellaneous PBAPS Summer Performance Monitoring Update July 17, 2019 Procedures OP-AA-108-107- Station Response to Grid Capacity Conditions Revision 7 1001 71111.04Q Corrective Action 4264530 Documents Drawings 6280-M-330 Emergency Cooling System Revision 38 280-M-362, CS Cooling System Revision 64 Sheet 1 Procedures ST-O-014-301-3 CS Loop A Pump, Valve, Flow, and Cooler Functional and Revision 34 Inservice Test 71111.05Q Fire Plans PF-132 Diesel Generator Building, General Area - Elevation 127'-0" Revision 9 PF-13D Unit 3 Reactor Building, 3 'A' and 3 'C' CS Room, Elevation Revision 3 91'-6" PF-3 Unit 2 Reactor Building, 2 'B' and 2 'D' RHR Pump and Heat Revision 6 Exchanger Room, Elevation 91'-6"/116'-0" PF-59 Unit 2 Reactor Building, HPCI Room, Elevation 88'-0" Revision 7 71111.06 Corrective Action 2705919 Documents Miscellaneous PBAPS UFSAR Appendix J Revision 21 Procedures RT-O-010-415-3 HPSW to RHR Emergency Cross-Tie Valve Functional Test Revision 5 ST-O-032-501-3 HPSW Valves Remote Position Indication Verification Revision 6 T-231-3 HPSW Injection Into the Torus Revision 10 71111.12 Corrective Action 4273687 Documents Procedures ER-AA-450 Structures Monitoring Revision 7 ER-PB-450-1006 Peach Bottom Structures Monitoring Instructions Revision 6 71111.13 Corrective Action 4264554 Documents 71111.15 Corrective Action 1415409 (E02), Documents 4249845, 271243, Inspection Type Designation Description or Title Revision or Procedure Date 272385, 272625 Drawings 6280-M-319, Makeup Demineralizer Water Revision 53 Sheet 2 Procedures AO 52E.3.A Diesel Generator Jacket Coolant System Fill During a LOOP Revision 0 SO 52A.8.C Diesel Generator Running Inspection Revision 43 71111.17T Corrective Action 1462769 Documents 2401565 2633582 4011762 Corrective Action 4282184 Documents Resulting from Inspection Procedures GP-20 Temporarily Defeating ECCS Auto Initiation Signal during Revision 15 Outages and 16 M-004-200 Reactor Pressure Vessel Disassembly Revision 39 SE-1 Plant Shutdown from the Remote Shutdown Panel Revision 23 71111.18 Engineering IP-ENG-001 Spare E-1 Diesel Failed Cables Revision 0 Changes FORM 2, EC 28399 IP-ENG-001 E-1 to E-4 EDGs Cables Replacement Revision 12 FORM 2, EC 28400 Procedures ER-AA-300-150 Cable Condition Monitoring Program Revision 5 MA-AA-716-012 Attachment 1, 480V/4160v/6900V & 13.2 KV Switchgear Revision 24 Breakers Test Matrix Work Orders 4926277 26277-12 71111.19 Corrective Action 4264289 Documents 4266600 269448 269804 Miscellaneous EDG Cable Replacement Project(s) July 2019 Inspection Type Designation Description or Title Revision or Procedure Date VBS-0757A ECT Fan A Vibration Procedures LS-2920B 'B' CS Room Flooding Level MA-AA-716-012 Post-Maintenance Testing Revision 22 S12R-63A-356- Electronic Calibration/Functional Check of the ESW Radiation Revision 0 XXCE Monitor RIS-0-17-356 ST-O-052-211-2 E-1 Diesel Generator Slow Start Full Load and IST Test Revision 27 Work Orders 4921655 26277-43 71111.22 Corrective Action 4282390 Documents Procedures SI2I-54-E42- Functional Test of E-42 4KV Undervoltage Relays Revision 2 XXFQ 71152 Corrective Action 0656157, Documents 1511027, 3963696, 3969726, 20194, 203289, 204454, 240533, 249035, 241082, 241090, 247715, 248920, 251551, 252679, 252875, 253195, 255204, 252216, 256520, 257453, 257456, Inspection Type Designation Description or Title Revision or Procedure Date 257458, Procedures ER-AA-300-150 Cable Condition Monitoring Program Revision 5 MA-PB-743-002 Tan Delta Cable Testing Revision 4 PI-AA-126-1001- Self-Assessment Revision 2 F-01 17| ]]