IR 05000259/2019004
| ML20042C802 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 02/10/2020 |
| From: | Tom Stephen NRC/RGN-II/DRP/RPB5 |
| To: | Jim Barstow Tennessee Valley Authority |
| A. Stephen RGN-II/DRP | |
| References | |
| IR 2019004 | |
| Download: ML20042C802 (24) | |
Text
February 10, 2020
SUBJECT:
BROWNS FERRY NUCLEAR PLANT - INTEGRATED INSPECTION REPORT 05000259/2019004, 05000260/2019004, 05000296/2019004 AND 07200052/2019002
Dear Mr. Barstow:
On December 31, 2019, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Browns Ferry Nuclear Plant. On January 24, 2020, the NRC inspectors discussed the results of this inspection with Steven M. Bono, Site Vice President, and other members of your staff. The results of this inspection are documented in the enclosed report.
Three findings of very low safety significance (Green) are documented in this report. Two of these findings involved violations of NRC requirements. We are treating these violations as non-cited violations (NCVs) consistent with Section 2.3.2 of the Enforcement Policy.
If you contest the violations or the significance or severity of the violations 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 II; the Director, Office of Enforcement; and the NRC Resident Inspector at Browns Ferry Nuclear Plant.
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 II; and the NRC Resident Inspector at Browns Ferry Nuclear Plant. 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,
/RA/
Thomas A. Stephen, Chief Reactor Projects Branch 5 Division of Reactor Projects
Docket Nos. 05000259, 05000260,
05000296 and 07200052 License Nos. DPR-33, DPR-52 and DPR-68
Enclosure:
As stated
Inspection Report
Docket Numbers:
05000259, 05000260, 05000296 and 07200052
License Numbers:
Report Numbers:
05000259/2019004, 05000260/2019004, 05000296/2019004 and
07200052/2019002
Enterprise Identifier: I-2019-004-0070
I-2019-002-0099
Licensee:
Tennessee Valley Authority
Facility:
Browns Ferry Nuclear Plant
Location:
Athens, Alabama
Inspection Dates:
October 01, 2019 to December 31, 2019
Inspectors:
T. Stephen, Senior Resident Inspector
N. Hobbs, Resident Inspector
M. Kirk, Resident Inspector
D. Lanyi, Senior Operations Engineer
Approved By:
Thomas A. Stephen, Chief
Reactor Projects Branch 5
Division of Reactor Projects
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Browns Ferry Nuclear Plant, 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 Follow Site Procedures Results in Smoldering of Main Feed Water System Electrical Wires Cornerstone Significance Cross-Cutting Aspect Report Section Initiating Events Green FIN 05000260/2019004-01 Open/Closed
[H.4] -
Teamwork 71153 A self-revealed Green finding was identified when the licensee failed to follow their general operating instruction for breakers, 0-GOI-300-2, "Electrical." Specifically, the licensee failed to inspect a 250V molded case circuit breaker prior to re-closing the breaker, that had previously tripped during breaker restoration, as prescribed by procedure.
Unit 1 High Pressure Coolant Injection System Declared Inoperable due to Steam Supply Isolation Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000259/2019004-02 Open/Closed
[H.5] - Work Management 71153 A self-revealed Green finding and associated NCV of TS 5.4.1, "Procedures," was identified when the licensee failed to comply with NPG-SPP-22.206, "Verification Program," which resulted in the inadvertent isolation and inoperability of Unit 1 HPCI.
Unit 2 Automatic Reactor Scram during Startup due to Intermediate Range Monitor Noise Cornerstone Significance Cross-Cutting Aspect Report Section Initiating Events Green NCV 05000260/2019004-03 Open/Closed
[P.5] -
Operating Experience 71153 A self-revealed Green finding and NCV of 10 CFR Part 50, Appendix B, Criterion XVI,
"Corrective Action," was identified for the licensee's failure to correct an electrical noise issue associated with the neutron monitoring system, which resulted in a Unit 2 reactor scram.
Additional Tracking Items
Type Issue Number Title Report Section Status LER 05000259/2019-001-01 LER 2019-001-01 for Browns Ferry Nuclear Plant,
Unit 1, High Pressure Coolant Injection System 71153 Closed
Declared Inoperable due to Steam Supply Isolation LER 05000260/2019-003-00 LER 2019-003-00 for Browns Ferry Nuclear Plant,
Unit 2, Automatic Reactor Scram during Startup due to Intermediate Range Monitor Noise 71153 Closed LER 05000259/2019-001-00 LER 2019-001-00 for Browns Ferry Nuclear Plant,
Unit 1, High Pressure Coolant Injection System Declared Inoperable due to Steam Supply Isolation 71153 Closed LER 05000260/2019-001-01 LER 2019-001-01 for Browns Ferry Nuclear Plant,
Unit 2, Traversing In-core Probe Purge Header Check Valve Leak Rate in Excess of Technical Specifications Limits.
71153 Closed
PLANT STATUS
Unit 1 operated at or near rated thermal power (RTP) until November 23, 2019, when the unit was down powered to approximately 68 percent power due to oscillations of turbine control valve #2. Repairs were made to the #2 turbine control valve and the valve was restored to operation. On November 24, 2019, the unit down powered to 50 percent power for additional maintenance activities to the #4 turbine stop valve. Maintenance was completed on the #4 turbine stop valve and the unit returned to RTP on November 25, 2019 and remained there for the rest of the inspection period.
Unit 2 began the inspection period in a planned outage to support repairs to the condenser. On October 1, 2019, during unit start up, the unit scrammed due to a valid actuation of the reactor protection system. The licensee determined that electrical noise sensed by the neutron monitoring system was the cause of the scram. Repairs were made to the neutron monitoring system, and the unit entered Mode 1 on October 8, 2019. The unit continued power ascension until October 12, 2019, when the unit was down powered to approximately 40 percent power to make repairs to variable frequency drives associated with the 2B recirculation pump. Repairs were completed and the unit returned to RTP on October 14, 2019. The unit remained at RTP until December 21, 2019, when unit was down powered to 50 percent to repair condenser tube leaks. The leaks were repaired and the unit returned to RTP on December 24, 2019, and remained there for the rest of the inspection period.
Unit 3 operated at or near RTP until November 7, 2019 when the unit was down powered to approximately 60 percent power for power suppression testing. Power suppression testing was completed and the unit returned to RTP on November 10, 2019. On November 16, 2019, the unit was shut down to determine the source of increased unidentified leakage in the drywell and make repairs to a feed water check valve that was determined to be the source of the increased unidentified leakage. Repairs were completed during the outage and the unit returned to RTP on December 3, 2019, and remained there for the rest of the inspection period.
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.
REACTOR SAFETY
71111.04Q - Equipment Alignment
Partial Walkdown Sample (IP Section 03.01) (2 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
- (1) Unit 3, System 31, Shutdown board room chillers and electric board room air conditioning units on October 28, 2019.
- (2) Unit 3, System 78, Fuel pool cooling system on November 4, 2019.
71111.04S - Equipment Alignment
Complete Walkdown Sample (IP Section 03.02) (1 Sample)
- (1) The inspectors evaluated system configurations during a complete walkdown of the Unit 3 High Pressure Coolant Injection (HPCI) system on November 21, 2019.
71111.05Q - Fire Protection
Quarterly Inspection (IP Section 03.01) (5 Samples)
The inspectors evaluated fire protection program implementation in the following selected areas:
- (1) Unit 1, Auxiliary Instrument Room #1 on December 12, 2019.
- (2) Unit 2, Electric Board Room 2A ('B' 4kV) and 250 V Battery Rooms on December 19, 2019.
- (3) Unit 2, Electric Board Room 2B ('D' 4kV) on December 19, 2019.
- (4) Unit 3, Control Bay Chiller Room on December 30, 2019.
- (5) Unit 3, 3B Electric Board Room on December 30, 2019.
71111.11A - Licensed Operator Requalification Program and Licensed Operator Performance
Requalification Examination Results (IP Section 03.03) (1 Sample)
- (1) The licensee completed the annual requalification operating examinations required to be administered to all licensed operators in accordance with Title 10 of the Code of Federal Regulations 55.59(a)(2), "Requalification Requirements," of the NRC's "Operator's Licenses." During the week of December 16, 2019, the inspector performed an in-office review of the overall pass/fail results of the individual operating examinations, the crew simulator operating examinations, and the biennial written examinations in accordance with Inspection Procedure (IP) 71111.11, "Licensed Operator Requalification Program." These results were compared to the thresholds established in Section 3.02, "Requalification Examination Results of IP 71111.11.
The inspectors reviewed and evaluated the licensed operator examination failure rates for the requalification annual operating exam and biennial written examination completed on December 12, 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 Sample)
- (1) The inspectors observed and evaluated licensed operator performance in the Control Room:
- Unit 2 startup and subsequent scram on October 1, 2019.
- Unit 2 startup on October 7, 2019.
- Unit 3 shutdown on November 15-16, 2019.
- Unit 3 startup on November 25, 2019.
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)
- (1) The inspectors observed and evaluated licensed operator requalification in the simulator on October 7, 2019.
71111.12 - Maintenance Effectiveness
Routine Maintenance Effectiveness Inspection (IP Section 02.01) (2 Samples)
The inspectors evaluated the effectiveness of routine maintenance activities associated with the following equipment and/or safety significant functions:
- (1) Unit 3, Electric Board Rooms (Function 31-R) and 4kV Shutdown Board Rooms (Function 31-S).
- (2) Units 1, 2, and 3, Reactor Protection System (RPS) following Unit 2 Scram (Function 099-B).
71111.13 - Maintenance Risk Assessments and Emergent Work Control
Risk Assessment and Management Sample (IP Section 03.01) (2 Samples)
The inspectors evaluated the risk assessments for the following planned and emergent work activities:
- (1) Risk associated with 3B DG and Unit 1 Loop I residual heat removal (RHR) system out of service for planned maintenance on October 8 - 11, 2019.
- (2) Risk associated with Unit 3 forced outage due to high decay heat load and feedwater out of service due to repairs on November 16, 2019.
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 02.02) (4 Samples)
The inspectors evaluated the following operability determinations and functionality assessments:
- (1) Unit 3, operability of control rod 06-47 with a foreign material exclusion (FME) plug installed in an exhaust port of an air valve originally discovered on September 28, 2019.
- (2) Unit 3, operability of 3EB Shutdown Battery Board battery bank after grounds discovered on September 30 and October 14, 2019.
- (3) Unit 2, operability of the residual heat removal service water (RHRSW) heat exchanger 2D inlet check valve discovered incorrectly assembled on December 9, 2019.
- (4) Unit 3, operability of primary containment isolation instrumentation after 3A main steam line flow indicator was discovered to have low indication on December 6, 2019.
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 modifications:
- (1) BFN-19-816-2, Unit 2 Intermediate Range Monitor (IRM) Mean Square Analog Module Signal Filter Circuit Change, Revision 0.
71111.19 - Post-Maintenance Testing
Post-Maintenance Test Sample (IP Section 03.01) (2 Samples)
The inspectors evaluated the following post maintenance tests:
- (1) Unit 3, post maintenance testing of 3B diesel generator following 6-year preventative maintenance and issues identified during maintenance on October 8-10, 2019.
- (2) Unit 3, post maintenance testing of reactor protection system (RPS) motor generator set 3B on October 22, 2019.
71111.20 - Refueling and Other Outage Activities
Refueling/Other Outage Sample (IP Section 03.01) (2 Samples)
- (1) The inspectors evaluated the Unit 2 forced outage that began during the previous inspection period and completed during this inspection period after a unit scram during startup on October 1, 2019. Repairs and modifications to intermediate range monitors (IRMs) followed the unit scram. The resident inspectors observed the unit startup on October 1, 2019, the subsequent scram due to intermediate range monitors spiking, drywell closeout and the unit startup. The unit transitioned to Mode 2 (Startup) on October 7, 2019.
- (2) The inspectors evaluated Unit 3 forced outage activities for steam jet air ejector repairs, and repairs of a main feed water check valve that was the cause for increased unidentified leakage in the drywell. The residents observed unit shutdown, foreign material exclusion (FME) controls during maintenance in the drywell and drywell closeout. The unit entered Mode 2 (Startup) in early morning hours of November 25, 2019
71111.22 - Surveillance Testing
The inspectors evaluated the following surveillance tests:
Surveillance Tests (other) (IP Section 03.01)
- (1) Unit 3, 3D diesel generator 24-hour surveillance run on December 15, 2019.
FLEX Testing (IP Section 03.02) (1 Sample)
- (1) Flex diesel pump inspection on November 4,
OTHER ACTIVITIES - BASELINE
===71151 - Performance Indicator Verification
The inspectors verified licensee performance indicators submittals listed below:
IE01: Unplanned Scrams per 7000 Critical Hours Sample (IP Section 02.01)===
- (1) Unit 1 (October 1, 2018 - September 30, 2019)
- (2) Unit 2 (October 1, 2018 - September 30, 2019)
- (3) Unit 3 (October 1, 2018 - September 30, 2019)
IE03: Unplanned Power Changes per 7000 Critical Hours Sample (IP Section 02.02) (3 Samples)
- (1) Unit 1 (October 1, 2018 - September 30, 2019)
- (2) Unit 2 (October 1, 2018 - September 30, 2019)
- (3) Unit 3 (October 1, 2018 - September 30, 2019)
IE04: Unplanned Scrams with Complications (USwC) Sample (IP Section 02.03) (3 Samples)
- (1) Unit 1 (October 1, 2018 - September 30, 2019)
- (2) Unit 2 (October 1, 2018 - September 30, 2019)
- (3) Unit 3 (October 1, 2018 - September 30, 2019)
71152 - Problem Identification and Resolution
Semiannual Trend Review (IP Section 02.02) (1 Sample)
- (1) The inspectors reviewed the licensees corrective action program for potential adverse trends in "Operator Performance and Maintenance Rework" that might be indicative of a more significant safety issue.
71153 - Followup of Events and Notices of Enforcement Discretion Event Report (IP Section 03.02)
The inspectors evaluated the following licensee event reports (LERs):
- (1) LER 05000260/2019-001-01, Traversing In-core Probe Purge Header Check Valve Leak Rate in Excess of Technical Specifications Limits (ADAMS accession: ML19353B487).
The inspectors reviewed the updated LER submittal. No additional findings or violations were identified. The circumstances surrounding this LER are documented in Inspection Report 05000259, 260, 296/2019-003 in IP 71153 and results sections.
- (2) LER 05000259/2019-001-01, High Pressure Coolant Injection System Declared Inoperable due to Steam Supply Isolation (ADAMS accession: ML19311C475).
The inspectors reviewed the updated LER submittal, as well as the original submittal in this quarter.
The circumstances surrounding this LER are documented in the Results Section.
- (3) LER 05000260/2019-003-00, Reactor Scram during Startup due to Intermediate Range Monitor Noise (ADAMS accession: ML19336B743).
The circumstances surrounding this LER are documented in the Results Section.
Personnel Performance (IP Section 03.03) (1 Sample)
- (1) Unit 2, The inspectors evaluated an electrical wire smoldering event associated with reactor feed-water system and the licensees performance that occurred on September 25,
OTHER ACTIVITIES
- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL
60855.1 - Operation of an Independent Spent Fuel Storage Installation at Operating Plants Operation of an Independent Spent Fuel Storage Installation at Operating Plants
- (1) The inspectors evaluated the licensees activates related to long-term operation and monitoring of their independent spent fuel storage installation.
The inspectors evaluated the following change reviews:
- Revision 7 to the ISFSI 10 CFR 72.212 Report for Evaluations for the HI-STORM 100 System
- Revision 5 to the ISFSI 10 CFR 72.212 Report for Evaluations for the
- HI-STORM FW System
- Revision 4 to MSI-0-079-DCS200.1(FW) Dry Cask Preparation and Startup
- Revision 4 to MSI-0-079-DCS500.4(FW) MPC-89 Unloading Preparations, Start Up and Shut Down
- Revision 4 to MSI-0-079-DCS500.5(FW) MPC-89 Unloading Operations
- Revision 4 to calculation CDQ007920050054 Analysis of postulated drop and tip over accidents of loaded HI-STORM system and stability of vertical cask crawler or vertical cask transporter on haul path
- Revision 7 to MSI-0-079-DCS300.5 Cask Transporter Operation
- Revision 7 to MSI-0-079-DCS500.3 MPC-68 Cooldown and Weld Removal
- Revision 7 to MSI-0-079-DCS500.5 MPC-68 Unloading Operations
- Revision 5 to MPC-BFN-003 Holtec HI-STORM FW Cask Loading Procedures
- Revision 5 to MPC-BFN-004 Multi-Purpose Canister (MPC) Welding Manual
71004 - Power Uprate
All inspection samples have been completed for the extended power uprates (EPUs) on Units 1, 2 and 3 as required by IP 71004, Power Uprate. A table in Attachment 1 to this report summarizes the samples that were inspected during the EPU project for each unit. The table is organized by the inspection procedure used to conduct the inspection activities and identifies the inspection reports where the samples are documented as well as the applicable units.
INSPECTION RESULTS
Failure to Follow Site Procedures Results in Smoldering of Main Feed Water System Electrical Wires Cornerstone Significance Cross-Cutting Aspect Report Section Initiating Events
Green FIN 05000260/2019004-01 Open/Closed
[H.4] -
Teamwork 71153 A self-revealed Green finding was identified when the licensee failed to follow their general operating instruction for breakers, 0-GOI-300-2, "Electrical." Specifically, the licensee failed to inspect a 250V molded case circuit breaker prior to re-closing the breaker, that had previously tripped during breaker restoration, as prescribed by procedure.
Description:
On September 25, 2019, while Unit 2 was in a forced outage, a troubleshooting work order (WO 120801020) of a 250V molded case circuit breaker was being performed. During the troubleshooting the breaker was reset and closed. The breaker tripped, and smoke was seen coming from within a main control room panel due to smoldering electrical wires in the panel.
Prior to this troubleshooting, on September 24, 2019, a work order was completed to replace a light socket on the panel for the main feed water system. When the work was completed, the licensee followed their process for restoration of the breaker supplying power to the light sockets. During the restoration, operations closed the breaker and it immediately tripped. Licensee staff then attempted to reset the breaker and it was documented that the breaker would not reset. A CR was generated to document the deficiency with the breaker. A troubleshooting work order (WO 120801020) was created to evaluate the failure to reset. The work order directed electrical maintenance personnel to attempt to reset the breaker with Operations' permission. If resetting was not successful, the direction was to replace the breaker under a new work order. During troubleshooting, the breaker was reset and closed without first understanding the reason for the initial trip. Following the re-closure, the breaker tripped, and smoke was seen coming from the associated panel in the main control room.
The licensee general operating instruction (GOI) for electrical breakers, 0-GOI-300-2, states for this type of breaker, if it immediately trips after closing, no further attempts are to be made to re-close. It also states to initiate a condition report (CR) to have the breaker inspected. Licensee staff failed to follow the applicable procedural steps.
Corrective Actions: The licensee's fire brigade and other required members of the Operations staff, responded to the event. No extinguishing agents were needed, and no fire suppression systems actuated. The licensee performed inspections of the damaged wires and repaired them. The licensee also performed a Level 1 Evaluation to identify the root cause, contributing causes and corrective actions to prevent recurrence.
Corrective Action References: Condition Report 1552023
Performance Assessment:
Performance Deficiency: The licensee failed to follow electrical procedures for breaker operation. Specifically, licensee staff closed a 250V molded case circuit breaker that had previously tripped prior to re-closing the breaker, without performing an inspection in accordance with 0-GOI-300-2, "Electrical." The failure to follow the procedure led to smoldering of electrical wires associated with main feed water light indications in the control room during a Unit 2 forced outage.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Protection Against External Factors attribute of the Initiating Events cornerstone and adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, the failure to correctly implement the procedure for electrical breaker operation introduced an ignition source due to an electrical short associated with a recently replaced light socket.
Significance: The inspectors assessed the significance of the finding using Appendix G, Shutdown Safety SDP. The inspectors performed an evaluation and determined that the equipment directly affected by this event would not have caused a shutdown initiating event as defined in IMC 0609 Appendix G. The inspectors also considered the following information during their evaluation of the significance of the finding: the main control room is a continuously manned area, the fire detection system worked as designed, the breaker in question tripped as designed upon sensing a short, and the fire brigade responded in an adequate amount of time. Using the Initiating Events screening questions for External Event Initiators, the inspectors answered no to the question of; did the finding increase the likelihood of a fire or internal/external flood that could cause a shutdown initiating event.
Cross-Cutting Aspect: H.4 - Teamwork: Individuals and work groups communicate and coordinate their activities within and across organizational boundaries to ensure nuclear safety is maintained.
Enforcement:
Inspectors did not identify a violation of regulatory requirements associated with this finding.
Unit 1 High Pressure Coolant Injection System Declared Inoperable due to Steam Supply Isolation Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems
Green NCV 05000259/2019004-02 Open/Closed
[H.5] - Work Management 71153 A self-revealed Green finding and associated NCV of TS 5.4.1, "Procedures," was identified when the licensee failed to comply with NPG-SPP-22.206, "Verification Program," which resulted in the inadvertent isolation and inoperability of Unit 1 HPCI.
Description:
On July 12, 2019, licensee personnel were performing preventative maintenance (WO 119335168) on the Unit 1 pressure suppression chamber (PSC) system when incorrect components were manipulated, resulting in an isolation signal to the high pressure coolant injection (HPCI) system. Specifically, the work order contained instructions for performing a functional test of the PSC head tank suction valve interlock relays, located in the Unit 1 auxiliary instrument room. During performance of the work order, licensee personal entered the incorrect relay panel which contained relays for the Unit 1 HPCI system, adjacent to the panel which contained the PSC valve relays. The licensee performed a continuity check in the incorrect panel, which completed the circuit for Unit 1 HPCI low level initiation and isolation. This resulted in the inadvertent isolation of Unit 1 HPCI. HPCI was declared inoperable at 4:40 PM on July 12, and it was declared operable at 9:10 PM the same evening.
Step 3.0.F of the maintenance procedure in use, EPI-0-075-RLY001, Revision 3, specified verifications of actions and component configurations to be performed in accordance with the Verification Program procedure. The procedure in effect at the time was NPG-SPP-22.206, Verification Program, Revision 5.
Corrective Actions: Following the isolation, operators responded appropriately and restored HPCI to operable status the same evening. A "stop-work stand-down" was implemented for the maintenance department following the event, and a Level 2 Evaluation was performed.
Corrective Action References: CR 1532170
Performance Assessment:
Performance Deficiency: The licensee's failure to perform an adequate component verification during maintenance was a performance deficiency. Specifically, a continuity check was performed on the incorrect relays, which led to the isolation of HPCI.
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.
Significance: The inspectors assessed the significance of the finding using Appendix A, The Significance Determination Process (SDP) for Findings At-Power. Using the Mitigating Systems screening questions, the finding was determined to be of very low safety significance (Green) because HPCI was able to be un-isolated and returned to operable status following the inadvertent isolation signal.
Cross-Cutting Aspect: H.5 - Work Management: The organization implements a process of planning, controlling, and executing work activities such that nuclear safety is the overriding priority. The work process includes the identification and management of risk commensurate to the work and the need for coordination with different groups or job activities.
Enforcement:
Violation: TS 5.4.1, Procedures, required, in part, that written procedures be established, implemented, and maintained covering activities related to procedures recommended in Regulatory Guide 1.33, Revision 2, Appendix A, February 1978. Regulatory Guide 1.33, Section 9, Procedures for Performing Maintenance, required that maintenance that can affect the performance of safety-related equipment should be properly pre-planned and performed in accordance with written procedures, documented instructions, or drawings appropriate to the circumstances. Contrary to the above, on July 12, 2019 from 4:40 PM to 9:10 PM, while performing maintenance testing, the licensee failed to adhere to NPG-SPP-22.206, Verification Program, Revision 5, which required work to be performed with correct component verification.
Enforcement Action: This violation is being treated as an non-cited violation, consistent with Section 2.3.2 of the Enforcement Policy.
Unit 2 Automatic Reactor Scram during Startup due to Intermediate Range Monitor Noise Cornerstone Significance Cross-Cutting Aspect Report Section Initiating Events
Green NCV 05000260/2019004-03 Open/Closed
[P.5] -
Operating Experience 71153 A self-revealed Green finding and NCV of 10 CFR Part 50, Appendix B, Criterion XVI, "Corrective Action," was identified for the licensee's failure to correct an electrical noise issue associated with the neutron monitoring system, which resulted in a Unit 2 reactor scram.
Description:
On October 1, 2019, at 3:07 AM Unit 2 received a reactor scram due to electrical noise from the intermediate range monitors (IRMs), of the neutron monitoring system (NMS). The unit was in the process of starting up from a forced outage and was at less than 1% power. The scram occurred as operators depressed the "Drive Out" button in order to withdraw two source range monitors (SRMs) via the drive motors. Troubleshooting revealed that electrical noise was induced by the SRM drive motors and picked up by the IRMs. Specifically, five of the eight IRMs received an electrical noise spike and displayed "High-High" indication, which caused a full reactor scram. No safety systems experienced any complications following the scram, and operators acted appropriately to return the unit to a safe shutdown condition.
Troubleshooting discovered the under-vessel cable connectors to be degraded for four of the eight IRMs. Browns Ferry has experienced both half scrams and full scrams in the past due to IRM spiking issues, and this has been a known industry issue. Half scrams occur when one of the two channels of the reactor protection system's logic sense a scram signal. Rod motion only occurs with a full scram, when both channels sense a scram signal.
Corrective Actions: Immediately following the scram, operators returned the unit to a safe shutdown condition. The licensee performed complex troubleshooting and worked with a vendor for cable and drive motor testing. A Level 1 Evaluation was performed to identify the root cause and contributing causes and develop corrective actions to prevent recurrence.
Corrective Action References: CR 1553492
Performance Assessment:
Performance Deficiency: The failure to adequately correct a condition adverse to quality associated with neutron monitoring system electrical noise, a repeat site issue and known industry issue, was a performance deficiency.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Equipment Performance attribute of the Initiating Events cornerstone and adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations.
Significance: The inspectors assessed the significance of the finding using Appendix A, The Significance Determination Process (SDP) for Findings At-Power. Using the Initiating Events screening questions, it was determined to be of very low safety significance (Green) because the scram was not concurrent with the loss of mitigation equipment.
Cross-Cutting Aspect: P.5 - Operating Experience: The organization systematically and effectively collects, evaluates, and implements relevant internal and external operating experience in a timely manner.
Enforcement:
Violation: Title 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, states that 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. Contrary to the above, from February 25, 2017, until October 1, 2019, the licensee failed to adequately correct an electrical noise issue associated with the neutron monitoring system, a repeat site issue and known industry issue, which led to a reactor scram.
Enforcement Action: This violation is being treated as an non-cited violation, 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 January 24, 2020, the inspectors presented the integrated inspection results to Steven M. Bono, Site Vice President, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
71111.04Q Corrective Action
Documents
CR 1526217
CR 1526220
EACE 1541523
Level 2 Evaluation Report
Drawings
3-47E855-1
Flow Diagram Fuel Pool Cooling System
Revision 26
3-76N3S-2
Mechanical P.I.D. Piping Schematic EBR ACU 3B
Revision 1
Work Orders
Corrective Action
Documents
CR 1565344, CR
1565390
Drawings
3-47E812-1
Flow Diagram High Pressure Coolant Injection System
Revision 73
Work Orders
71111.05Q Procedures
FPR-Volume 2
Fire Protection Report Volume 2
Revision 65
Corrective Action
Documents
CR 1541401,
1541460
CR 1564168.
1557386,
1553492,
1544253,
1542569
Miscellaneous
System Health Report for System 99, Reactor Protection
System
System Health Report for System 31 (CREVs/Control Bay
HVAC)
Air Condition System 31 (a)(1) Plan
Revision 10
CDE 2282, 2221,
22, 2303, 2219,
269, 2300, 2301,
250, 2281
Cause Determination Evaluation records
CDE 2318, 2305,
296, 2210, and
2165
Cause Determination Evaluation records
Procedures
0-TI-346
Maintenance Rule Performance Indicator Monitoring,
Trending and Reporting - 10CFR50.65
Revision 52
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Corrective Action
Documents
CR 1553674,
1552900,
1552862,
1556743,
1553140,
1571318
Work Orders
Calculations
NDQ099880167
Transient Analysis Design Report
Revision 8
Corrective Action
Documents
CR 1555377
Unit 2 Reactor Scram
Engineering
Changes
BFN-19-816
Intermediate Range Monitor (IRM) Mean Square Analog
Module Signal Filter Circuit Change
Revision 0
BFN-19-816-02
Unit 2 Intermediate Range Monitor (IRM) Mean Square
Analog Module Signal Filter Circuit Change
Revision 0
Engineering
Evaluations
10CFR50.59 Screening Review Form for Increasing IRM
Trip Time Constant
Revision 0
FS1-0046479
Impact of Increased IRM Delay Time for Continuous Rod
withdrawal in Startup Range
Revision 1
Work Orders
Troubleshoot Unit 2 Reactor Scram due to IRM noise
Corrective Action
Documents
CR 1555241,
1555242,
1555248.
1558951
Procedures
EPI-0-099-
MGZ002
Reactor Protection System M-G Sets Preventative
Maintenance
Revision 26
Work Orders
20835068,
20174209,
20834967,
119632278
Work Orders
119700396
71151
Miscellaneous
Operator logs
10/01/2018
to
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
09/30/2019
Procedures
Regulatory Assessment Performance Indicator Guidelines
Revision 7
Engineering
Evaluations
CFR 50.59 Evaluation Form to Increase IRM Trip time
Constant
Revision 0
Self-Assessments
Site Trimester Performance Assessment
February
2019 - May
2019
BFN Maintenance Department Performance Assessment
August 2019
BFN Operations Department Performance Assessment
July 2019 to
August 2019
Corrective Action
Documents
CR 1552023, CR
1551812, CR
1563889
Level 1
Evaluation for CR
1552023
Procedures
0-GOI-300-2
Electrical
Revision 156
0-MEG-TRBSHT-
001
Initial Troubleshooting
Revision 2
ECI-0-000-
BKR008
Testing and Troubleshooting of Molded Case Circuit
Breakers and Motor Starter Overload Relays
Revision 108
MMDP-1
Maintenance Management System
Revision 38
NPG-SPP-06.14
Guidelines for Planning and Execution of Troubleshooting
Activities
Revision 8
Work Orders
Inspection Procedure
Sample
Inspection Report ML
Number
U-1, U-2, U-3, ALL
71004
Reviewed the Flow
Acceleration Corrosion
Program and Erosion
Corrosion Program
ALL
Observed the following
for Unit 3:
Power ascension
above previous
license limit
Simulator
Training
associate with
New operator
actions
Procedure
changes
Vibration data per
3-TI-701
ML18221A146
U-3
Observed the following
for Unit 1:
Power ascension
above previous
license limit
Simulator
Training
associate with
New operator
actions
Procedure
changes
Vibration data per
1-TI-701
ML19129A276
U-1
Observed the following
for Unit 2:
Power ascension
above previous
license limit
Simulator
Training
associate with
New operator
actions
Procedure
changes
Vibration data per
2-TI-701
U-2
Inspection Procedure
Sample
Inspection Report ML
Number
U-1, U-2, U-3, ALL
Reviewed the following
Engineering Change
(EC) packages:
EC 67324, Modify
FWCS Software
EC 72342, Modify
EHC Software
ALL
DCN 65786,
BFN-2
Emergency Core
Cooling System
(ECCS) Ring
Header Piping
Modification
U-2
Reviewed the following
plant modifications:
DCN 71586,
Replacement
Steam Dryer
ALL
DCN 69424,
Replace
Condenser
Vacuum Pressure
Switches with
Pressure
Transmitters
ALL
DCN 69389,
Reactor
Recirculation
Motor
Replacement
EPU Additional
Changes
U-1
DCN 72642,
design change to
ATWS/ARI
setpoints related
to EPU
U-2
Changes to RHR
heat exchanger
requirements due
to EPU
U-2
Evaluated the following
following modifications:
Surveillance for
Standby Liquid
Control (SLC)
system
enrichment
U-3
Inspection Procedure
Sample
Inspection Report ML
Number
U-1, U-2, U-3, ALL
Observed and
reviewed Unit 3
EPU integrated
system testing
per 3-TI-700
ML18306A821
U-3
Observed and
reviewed Unit 1
EPU integrated
system testing
per 1-TI-700
ML19129A276
U-1
Observed and
reviewed Unit 2
EPU integrated
system testing
per 2-TI-700
ML19303C165
U-2
DCN 51143,
Inboard MSIV
changes required
for power uprate
DCN 69118,
Turbine First
Stage Pressure
Scram Bypass
Setpoint Change
ALL
Reviewed the following
tests:
3-SR-3.3.1.1.13
APRM 1-4
calibrations per
DCN 68463
Stage 4
associated with
the Extended
(EPU)
modification
U-3
Surveillance for
Primary
Containment
Isolation System
High Flow
Instrument
Calibrations per
ECP 51243 Stage
associated
with EPU
U-1
Inspection Procedure
Sample
Inspection Report ML
Number
U-1, U-2, U-3, ALL
Reviewed the following:
Regulatory
Commitments
related to EPU
ALL
Problem
Identification and
Resolution
related to EPU for
Unit 3
U-3
Problem
Identification and
Resolution
related to EPU for
Unit 1
U-1
Problem
Identification and
Resolution
related to EPU for
Unit 2
U-2