On April 29. 2017 at 18:44. the Reactor was manually tripped by the operators at approximately 12% power in response to a feedwater isolation caused by I ugh Steam Generator ( SG) Level on the 'B' SG. The feedwater isolation signal P-14 was automaticall) actuated at 18:43 when the 'B' SG level reached the setpoint 0 r 90.8?..o narrow ranue level. The plant was being started up following the major work perlbrmed for Refueling Outage 18. No adverse consequences resulted from this event.
Post-trip investigation revealed that FW-LT-502-V 1 L (the Variable leg pressure isolation for FW-LT-502) had not been restored to the required open position during routine instrument line filling and venting. On April 26. 2017. l&C' performed hacklilline of the reference legs on multiple steam generator level channels. including FW-1.T-502. the '13' SG wide range level instrument.
1:W-LT-502- VII. not being restored to the open position caused the 'B' SG wide range indication to respond slowly to level changes resulting in overfeeding the 'B' steam generator. The cause of the event was determined to be failure of the l&C technician to properly implement maintenance fundamentals during the performance of restoration of FW-LT-502. Individual perlbrmance was corrected. A contributing cause was determined to be improper characterization or SG level hack fill activity as skill-of-the-craft. Planned corrective actions include development of a maintenance procedure to provide specific step-by-step instructions. |
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Category:Letter
MONTHYEARML24009A1152024-01-29029 January 2024 Exemption from Select Requirements of 10 CFR Part 73 (EPID L 2023 LLE-0043 (Security Notifications, Reports, and Recordkeeping and Suspicious Activity Reporting)) L-2024-010, Point Units 3 and 4, Seabrook, Duane Arnold, and Point Beach Units 1 and 2, Nuclear Property Insurance - 10 CFR 50.54(w)(3)2024-01-25025 January 2024 Point Units 3 and 4, Seabrook, Duane Arnold, and Point Beach Units 1 and 2, Nuclear Property Insurance - 10 CFR 50.54(w)(3) ML24022A0652024-01-22022 January 2024 Senior Reactor and Reactor Operator Initial License Examinations L-2024-003, NextEra Energy Seabrook, LLC - 10 CFR 50.46 - Emergency Core Cooling System LBLOCA 30-Day Report2024-01-11011 January 2024 NextEra Energy Seabrook, LLC - 10 CFR 50.46 - Emergency Core Cooling System LBLOCA 30-Day Report ML23312A1822023-12-22022 December 2023 Issuance of Amendment No. 172 Revision to Cooling Tower Service Water Loop or Cell Requirements L-2023-173, Quality Assurance Topical Report (FPL-1) Revision 30 Update2023-12-15015 December 2023 Quality Assurance Topical Report (FPL-1) Revision 30 Update L-2023-180, Submittal of Changes to the Technical Specification Bases2023-12-13013 December 2023 Submittal of Changes to the Technical Specification Bases L-2023-177, Supplement to Seabrook Exemption Request Regarding Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Final Rule2023-11-29029 November 2023 Supplement to Seabrook Exemption Request Regarding Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Final Rule L-2023-155, Supplement to Response to Request for Additional Information, Revised NextEra Common Emergency Plan, and Revised Site-Specific Emergency Plan Annexes Regarding License Amendment Request for Common Emergency Plan Consistent with NUREG-06542023-11-28028 November 2023 Supplement to Response to Request for Additional Information, Revised NextEra Common Emergency Plan, and Revised Site-Specific Emergency Plan Annexes Regarding License Amendment Request for Common Emergency Plan Consistent with NUREG-0654, L-2023-160, Part 73 Exemption Request Regarding Enhanced Weapons, Firearms, Background Checks, and Security Event Notifications Final Rule2023-11-16016 November 2023 Part 73 Exemption Request Regarding Enhanced Weapons, Firearms, Background Checks, and Security Event Notifications Final Rule ML23318A0772023-11-14014 November 2023 Request for Information and Notification of Conduct of IP 71111.21.N.04, Age-Related Degradation, Reference Inspection Report 05000443/2024011 IR 05000443/20234032023-11-0707 November 2023 Security Baseline Inspection Report 05000443/2023403 and Independent Spent Fuel Storage Installation 07200063/2023401 IR 05000443/20230032023-11-0606 November 2023 Integrated Inspection Report 05000443/2023003 IR 05000443/20230102023-10-19019 October 2023 Triennial Fire Protection Inspection Report 05000443/2023010 ML23346A1322023-10-0606 October 2023 Communication from C-10 Research & Education Foundation Regarding NextEra Common Emergency Fleet Plan License Amendment Request and Related Documents Subsequently Published ML23275A0522023-10-0202 October 2023 Requalification Program Inspection IR 05000443/20234012023-09-0808 September 2023 Cybersecurity Inspection Report 05000443/2023401 (Cover Letter Only) IR 05000443/20234202023-09-0505 September 2023 Security Baseline Inspection Report 05000443/2023420 IR 05000443/20230052023-08-31031 August 2023 Updated Inspection Plan for Seabrook Station (Report 05000443/2023005) L-2023-114, Proposed Turkey Point Units 6 and 7; Seabrook Station; Point Beach Units 1 and 2 - Official Service List Update2023-08-17017 August 2023 Proposed Turkey Point Units 6 and 7; Seabrook Station; Point Beach Units 1 and 2 - Official Service List Update IR 05000443/20233022023-08-16016 August 2023 Operator Licensing Retake Examination Report 05000443/2023302 IR 05000443/20230022023-08-0808 August 2023 Integrated Inspection Report 05000443/2023002 L-2023-098, and Point Beach Units 1 and 2 - Response to Request for Additional Information Regarding License Amendment Request for Common Emergency Plan Consistent with NUREG-0654, Revision 22023-08-0707 August 2023 and Point Beach Units 1 and 2 - Response to Request for Additional Information Regarding License Amendment Request for Common Emergency Plan Consistent with NUREG-0654, Revision 2 ML23201A0872023-08-0303 August 2023 Audit Plan in Support of Review of License Amendment L-2023-104, Preparation and Scheduling of Operator Licensing Examinations2023-08-0303 August 2023 Preparation and Scheduling of Operator Licensing Examinations L-2023-103, Inservice Inspection Examination Report2023-08-0303 August 2023 Inservice Inspection Examination Report ML23192A0782023-07-11011 July 2023 Operator Licensing Retake Examination Approval L-2023-087, Florida Power & Light/Nextera Energy, Results of the Safety Culture Program Effectiveness Review, March 20, 2023 (ADAMS Accession No. ML22340A452)2023-06-29029 June 2023 Florida Power & Light/Nextera Energy, Results of the Safety Culture Program Effectiveness Review, March 20, 2023 (ADAMS Accession No. ML22340A452) SBK-L-23053, Radiological Emergency Plan (Ssrep), Revision 802023-06-22022 June 2023 Radiological Emergency Plan (Ssrep), Revision 80 ML23157A0722023-06-0606 June 2023 Notification of Conduct of a Fire Protection Team Inspection L-2023-074, Addendum to 2021 Decommissioning Funding Status Reports / Independent Spent Fuel Storage Installation Ctsfsi) Financial Assurance Update2023-06-0202 June 2023 Addendum to 2021 Decommissioning Funding Status Reports / Independent Spent Fuel Storage Installation Ctsfsi) Financial Assurance Update L-2023-071, NextEra Energy Quality Assurance Topical Report (FPL-1) Revision 29 and Florida Power and Light Company Quality Assurance Program Description for 10 CFR Part 52 Licenses (FPL-2) Revision 11, Annual Submittal2023-05-22022 May 2023 NextEra Energy Quality Assurance Topical Report (FPL-1) Revision 29 and Florida Power and Light Company Quality Assurance Program Description for 10 CFR Part 52 Licenses (FPL-2) Revision 11, Annual Submittal IR 05000443/20233012023-05-15015 May 2023 Initial Operator Licensing Examination Report 05000443/2023301 L-2023-064, License Amendment Request 23-01, Revision 1, Update the Period of Applicability (Poa) for the Pressure-Temperature Limits (PTL) and Low Temperature Overpressure Protection (L Top) Curves2023-05-11011 May 2023 License Amendment Request 23-01, Revision 1, Update the Period of Applicability (Poa) for the Pressure-Temperature Limits (PTL) and Low Temperature Overpressure Protection (L Top) Curves IR 05000443/20230012023-05-11011 May 2023 Integrated Inspection Report 05000443/2023001 ML23129A0312023-05-0909 May 2023 Reactor Operator Retake License Examination ML23117A3652023-05-0404 May 2023 Supplemental Information Needed for Acceptance of Requested Licensing Action Amendment Request to Remove Period of Applicability from PTL and Low Temperature Over Pressure Protection Curves SBK-L-23044, 2022 Annual Radiological Environmental Operating Report2023-04-28028 April 2023 2022 Annual Radiological Environmental Operating Report SBK-L-23031, 2022 Annual Radioactive Effluent Release Report2023-04-28028 April 2023 2022 Annual Radioactive Effluent Release Report SBK-L-23033, 2022 Annual Environmental Operating Report2023-04-11011 April 2023 2022 Annual Environmental Operating Report L-2023-053, Core Operating Limits Report for Cycle 232023-04-0505 April 2023 Core Operating Limits Report for Cycle 23 ML23088A1522023-03-29029 March 2023 Summary of Meeting Between Nrc/Region I and C-10 - Questions Regarding Seabrook 4Q2022 Inspection Report L-2023-021, Units, 1 and 2, Turkey Point, Units 3 and 4, Seabrook Station and Point Beach, Units 1 and 2 - Decommissioning Funding Status Reports / Independent Spent Fuel Storage Installation (ISFSI) Financial Assurance Update2023-03-28028 March 2023 Units, 1 and 2, Turkey Point, Units 3 and 4, Seabrook Station and Point Beach, Units 1 and 2 - Decommissioning Funding Status Reports / Independent Spent Fuel Storage Installation (ISFSI) Financial Assurance Update L-2023-028, and Point Beach Units 1 and 2, 10 CFR 50.46 Annual Reporting of Changes to, or Errors in Emergency Core Cooling System Models or Applications2023-03-27027 March 2023 and Point Beach Units 1 and 2, 10 CFR 50.46 Annual Reporting of Changes to, or Errors in Emergency Core Cooling System Models or Applications ML23073A1562023-03-23023 March 2023 Relief Request 4RA-22-01, Relief from the Requirements of the ASME Code L-2023-012, License Amendment Request 23-01, Remove Period of Applicability (Poa) from Pressure Temperature Limits (PTL) and Low Temperature Overpressure Protection (L Top) Curves2023-03-15015 March 2023 License Amendment Request 23-01, Remove Period of Applicability (Poa) from Pressure Temperature Limits (PTL) and Low Temperature Overpressure Protection (L Top) Curves L-2023-025, Fleet Relief Request (Frr) 23-01, Proposed Alternative to ASME Section XI Authorizing Implementation of ASME Code Case N-752-12023-03-15015 March 2023 Fleet Relief Request (Frr) 23-01, Proposed Alternative to ASME Section XI Authorizing Implementation of ASME Code Case N-752-1 L-2023-029, and Point Beach Units 1 and 2 Nuclear Property Insurance - 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[Table view] Category:Licensee Event Report (LER)
[Table view] |
comments regarding burden estimate to the Information Services Branch (1--2 F43), U.S. Nuclear Regulatory Commission. Washington, DC 20555-0001, or by e-mail to rifocollects.Resource@rrc.gov, and to the Uesk Officer, Office of Information and Regulatory Affairs.
used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to: the information collection.
05000- Seabrook Station 443
Description of the Event
On April 29, 2017 at 18:44, the Reactor [AC,RCT] was manually tripped by the operators at approximately 12% power in response to a feedwater [SJ] isolation caused by High Steam Generator (SG) Level on the 'B' Steam Generator [AB, SG].
The control room operators were manually controlling SG levels while starting up the unit and were in the process of opening the main feedwater regulating valves. During low power operations, the wide range indication is used to more accurately control SG water levels as SG wide range level indication will lead narrow range level indication as feedwater flow to the steam generator changes.
The feedwater isolation signal P-14 was automatically actuated at 1843 when the 'B' SG level reached the setpoint of 90.8% narrow range level. The P-14 signal closes the main feedwater isolation valves, all feed regulating valves, and trips the main feedwater pumps. The plant was being started up following the major work performed for Refueling Outage 18.
Post-trip investigation revealed that FW-LT-502-V1L (the variable leg pressure isolation for FW-LT-502) had not been restored to the required open position during routine instrument line filling and venting. On April 26, 2017, l&C performed backfilling of the reference legs on multiple steam generator level channels, including FW-LT-502, the 'B' SG wide range level instrument. FW-LT-502-V1L not being restored to the open position caused the 'B' SG wide range indication to respond slowly to level changes.
The operating crew processed through E-0, Reactor Trip or Safety Injection (exited the procedure at Step 4 a RNO) to ES-0.1, Reactor Trip Response (exited at step 14 a RNO) to OS1000.11, Post Trip to Hot Standby.
Cause of the Event
The cause of the event was determined to be failure of the l&C technician to properly implement maintenance fundamentals during the restoration of FW-LT-502. A contributing cause was determined to be improper characterization of SG level backfill activity as skill-of-the-craft.
Analysis of the Event
Feedwater isolation on a high steam generator level prevents continuous addition of excessive feedwater, which could result in carryover of water into the steam lines and excessive cool down of the primary system.
Upon the P-14 actuation, the plant functioned correctly. All automatic functions occurred as designed, in the expected time frame. The Feedwater Isolation function was completed within seven seconds (based on a review of available computer points). The loss of feed flow required the operators to manually actuate a reactor trip at 18:44:26.
Without forward feed flow, SG levels quickly dropped. The emergency feedwater (EFW) actuation signal occurred due to two 'C' SG level instruments dropping below the 20% lo-lo set point. The 'B' EFW pump breaker closed immediately, and the turbine-driven EFW pump began to develop discharge pressure and was at normal operating pressure 11 seconds later.
Estimated burden per response tc comply with this mandatory collect:on request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington. DC 20555-0001, or by e-mail to Infccollects.Resource@nrc.gov. and to the Desk Officer: Office of Information and Regulatory Affairs:
NEOB-10202, (315C-0104). Office of Management and Budget. Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor. and a person is not reouired to respo".d to, the informatron collection.
05000- Seabrook Station 443 An EFW actuation also results in a SG blowdown isolation, and this function was performed within five seconds. Due to a lack of decay heat, the RCS temperature cooled to approximately 535 deg. F and a subsequent automatic letdown isolation occurred due to low pressurizer level at 17%. The crew then successfully stabilized the plant in Mode 3 at normal operating pressure and temperature and normal letdown and SG levels were restored. The event posed no actual or potential hazard to public health or safety.
The event resulted in a valid actuation of the reactor protection system and met the reporting criteria of 10 CFR 50.72(b) (2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A). A four hour report was made to the NRC at approximately 2119 on April 29, 2017 (event number 52718). Plant operators responded to the plant trip in accordance with approved procedures, and safety systems functioned as expected. No adverse consequences resulted from this event and this incident had no adverse impact on health and safety of the public or the plant and its personnel. This event did not involve a safety system functional failure.
Corrective Actions
Completed Corrective Actions
1. Individual performance was corrected.
2. All similar transmitter valve positions were verified. All valves were found in their correct position.
Planned Corrective Actions
1. Develop and present a case study on this event to l&C technicians that captures the specific details of this event and lessons learned.
2. Develop a maintenance procedure that provides specific step-by-step instructions to perform SG level channel backfilling operations.
Similar Events There have been no previous licensee event reports at Seabrook for a similar event.
Additional Information
The Energy Industry Identification System (EIIS) codes are included in this LER in the following format: [EIIS system identifier, EIIS component identifier].