08-18-2017 | On June 22, 2017, the Unit 1 Low Pressure Core Spray ( LPCS) system was declared inoperable due to loss of corner room area cooling and loss of motor cooling. The common diesel generator cooling water pump received an automatic trip signal while being secured. The LPCS pump remained in standby during the event. Troubleshooting identified the most likely cause for the trip of the emergency cooling water pump breaker was a malfunction of the cooling water pump control switch or the cooling water supply fan control relay. Both suspected components were replaced. The causal investigation did not identify a specific cause; however, there is a high level of confidence that the failure modes were eliminated by the corrective actions taken during troubleshooting.
This component inoperability is reportable in accordance with 10 CFR 50.73(a)(2)(v)(D) as an event or condition that could have prevented fulfillment of the safety function of structures or system that are needed to mitigate the consequences of an accident.
This condition could have prevented the LPCS system, a single train safety system, from performing its design function. There was minimal safety consequences associated with the condition since other required emergency safety systems remained operable, there were no actual demands for Unit 1 LPCS, and safety margins were maintained. |
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Category:Letter
MONTHYEARIR 05000373/20230042024-01-24024 January 2024 County Station - Integrated Inspection Report 05000373/2023004 and 05000374/2023004 ML24024A1332024-01-24024 January 2024 Confirmation of Initial License Examination IR 05000373/20230122024-01-18018 January 2024 County Station - Biennial Problem Identification and Resolution Inspection Report 05000373/2023012 and 05000374/2023012 ML23354A2902024-01-0505 January 2024 Exemption from Select Requirements of 10 CFR Part 73 (EPID L-2023-LLE-0028 (Security Notifications, Reports, and Recordkeeping and Suspicious Activity Reporting)) ML23360A6082023-12-27027 December 2023 County Station Request for Information for NRC Commercial Grade Dedication Inspection: Inspection Report 05000373/2024010 and 05000374/2024010 ML23278A1292023-12-14014 December 2023 Units 1 & 2; Limerick, Units 1 & 2; Nine Mile Point, Units 1 & 2; and Peach Bottom, Units 2 & 3 -Revision to Approved Alternatives to Use Boiling Water Reactor Vessel and Internals Project Guidelines ML23305A1402023-12-13013 December 2023 Units 1 & 2; Nine Mile Point, Unit 2; Peach Bottom, Units 2 & 3; and Quad Cities, Units 1 and 2 - Issuance of Amendments to Adopt Traveler TSTF-580 ML23317A1192023-11-10010 November 2023 Constellation Energy Generation, LLC - 2023 Annual Report - Guarantees of Payment of Deferred Premiums RS-23-120, Supplemental Information Letter for Part 73 Exemption Request - Responses to Request for Confirmatory Information2023-11-10010 November 2023 Supplemental Information Letter for Part 73 Exemption Request - Responses to Request for Confirmatory Information IR 05000373/20230032023-11-0909 November 2023 County Station Integrated Inspection Report 05000373/2023003, 05000374/2023003, and 07200070/2023001 ML23286A2602023-11-0808 November 2023 Issuance of Amendment Nos. 260 and 245 to Renewed Facility Operating Licenses Relocation of Pressure and Temperature Limit Curves to the Pressure Temperature Report IR 05000373/20234012023-11-0707 November 2023 County Station Security Baseline Inspection Report 05000373/2023401 and 05000374/2023401 RS-23-103, Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation2023-10-13013 October 2023 Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation RS-23-097, Constellation Energy Generation, LLC, Advisement of Leadership Changes and Submittal of Updated Standard Practice Procedures Plans2023-10-12012 October 2023 Constellation Energy Generation, LLC, Advisement of Leadership Changes and Submittal of Updated Standard Practice Procedures Plans IR 05000374/20230102023-10-11011 October 2023 NRC Inspection Report 05000374/2023010 IR 05000373/20233012023-09-15015 September 2023 Errata to NRC Initial License Examination Report 05000373/2023301; 05000374/2023301 RS-23-080, Constellation Energy Generation, LLC, Application to Revise Technical Specifications to Adopt TSTF-264-A, Revision 0, 3.3.9 and 3.3.10 - Delete Flux Monitors Specific Overlap Requirement SRs2023-08-30030 August 2023 Constellation Energy Generation, LLC, Application to Revise Technical Specifications to Adopt TSTF-264-A, Revision 0, 3.3.9 and 3.3.10 - Delete Flux Monitors Specific Overlap Requirement SRs RS-23-087, Revision to Approved Alternatives Associated with the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor2023-08-0404 August 2023 Revision to Approved Alternatives Associated with the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor ML23212A9012023-08-0303 August 2023 Regulatory Audit Report to Support the Review of the Amendments to Relocation of the Pressure Temperature Limit Curves to the Pressure and Temperature Limits Report IR 05000373/20230022023-08-0101 August 2023 County Station - Integrated Inspection Report 05000373/2023002 and 05000374/2023002 ML23208A3182023-07-27027 July 2023 Notification of an NRC Biennial Licensed Operator Requalification Program Inspection and RFI RS-23-084, Response to Request for Additional Information Regarding the Application to Revise Design Basis to Allow Use of Plastic Section Properties in Lower Downcomer Braces Analysis2023-07-24024 July 2023 Response to Request for Additional Information Regarding the Application to Revise Design Basis to Allow Use of Plastic Section Properties in Lower Downcomer Braces Analysis ML23192A5272023-07-12012 July 2023 NRC Initial License Examination Report 05000373/2023301; 05000374/2023301 ML23186A2062023-07-0606 July 2023 Information Request for a NRC Post-Approval Site Inspection for License Renewal 05000374/2023010 ML23181A1502023-06-30030 June 2023 Combined Response to Request for Additional Information and Supplemental Information in Support of LAR to Relocate Pressure and Temperature Limit Curves to the Pressure and Temperature Limits Report ML23178A2422023-06-28028 June 2023 Reassignment of the U.S. Nuclear Regulatory Commission Branch Chief in the Division of Operating Reactor Licensing for Plant Licensing Branch III IR 05000373/20230112023-06-26026 June 2023 County Station - Quadrennial Fire Protection Team Inspection Report 05000373/2023011 and 05000374/2023011 RS-23-077, Response to NRC Regulatory Issue Summary 2023-01, Preparation and Scheduling of Operator Licensing Examinations2023-06-16016 June 2023 Response to NRC Regulatory Issue Summary 2023-01, Preparation and Scheduling of Operator Licensing Examinations ML23167A0352023-06-16016 June 2023 Registration of Use of Cask to Store Spent Fuel ML23171A9562023-06-12012 June 2023 Post Exam Ltr RS-23-042, Application to Revise Technical Specifications to Adopt TSTF-580, Provide Exception from Entering Mode 4 with No Operable RHR Shutdown Cooling2023-05-25025 May 2023 Application to Revise Technical Specifications to Adopt TSTF-580, Provide Exception from Entering Mode 4 with No Operable RHR Shutdown Cooling IR 05000373/20230012023-05-10010 May 2023 County Station - Integrated Inspection Report 05000373/2023001 and 05000374/2023001 ML23123A2202023-05-0303 May 2023 Relief Request I4R-14 for Alternative Frequency to Containment Unbonded Post-Tensioning System Inservice Inspection ML23118A3472023-05-0101 May 2023 County, 1 & 2; Nine Mile Point, 2; and Quad Cities, 1 & 2 - Correction of Amendment No. 193 Adoption of TSTF-306, Revision 2, Add Action to LCO 3.3.6.1 to Give Option to Isolate the Penetration EPID L-2022-LLA-0143 ML23121A1612023-05-0101 May 2023 Information Meeting (Open House) with a Question-and-Answer Session to Discuss NRC 2022 End-of-Cycle Plant Performance Assessment of LaSalle County Station, Units 1 and 2 ML23114A2522023-04-28028 April 2023 Request to Use a Provision of a Later Edition of the ASME Boiler & Pressure Vessel Code, Section XI ML23081A0382023-04-25025 April 2023 County, 1 & 2; Nine Mile Point, 2; and Quad Cities, 1 & 2 - Issuance of Amendments to Adopt TSTF-306, Rev. 2, Add Action to LCO 3.3.6.1 to Give Option to Isolate the Penetration ML23110A3202023-04-21021 April 2023 Information Request to Support the NRC Annual Baseline Emergency Action Level and Emergency Plan Changes Inspection ML23107A1822023-04-18018 April 2023 Operator Licensing Examination Approval Lasalle County Station, May 2023 RS-23-049, Constellation Energy Generation, LLC, Report on Status of Decommissioning Funding for Reactors and Independent Spent Fuel Storage Installations2023-03-23023 March 2023 Constellation Energy Generation, LLC, Report on Status of Decommissioning Funding for Reactors and Independent Spent Fuel Storage Installations ML23073A2182023-03-22022 March 2023 Issuance of Amendment No. 258 to Renewed Facility Operating Licenses Exigent Amendment to Revise Design Basis Related to Seismic Requirements RS-23-048, Exigent Amendment Request to Revise Design Basis Related to Seismic Requirements2023-03-0707 March 2023 Exigent Amendment Request to Revise Design Basis Related to Seismic Requirements ML23061A1632023-03-0303 March 2023 Reassignment of the U.S. Nuclear Regulatory Commission Branch Chief in the Division of Operating Reactor Licensing for Plant Licensing Branch 3 IR 05000373/20220062023-03-0101 March 2023 Annual Assessment Letter for LaSalle County Station, Units 1 and 2 (Report 05000373/2022006 and 05000374/2022006) RS-23-045, Constellation Energy Generation, LLC Submittal of Fitness for Duty Performance Data Reports for 2022 Per 10 CFR 26.717(c) & 10 CFR 26.2032023-02-28028 February 2023 Constellation Energy Generation, LLC Submittal of Fitness for Duty Performance Data Reports for 2022 Per 10 CFR 26.717(c) & 10 CFR 26.203 RS-23-037, Annual 10 CFR 50.46 Report of Emergency Core Cooling System Evaluation Model Changes and Errors for LaSalle County Station2023-02-22022 February 2023 Annual 10 CFR 50.46 Report of Emergency Core Cooling System Evaluation Model Changes and Errors for LaSalle County Station ML23024A1372023-02-0303 February 2023 Request for Withholding Information from Public Disclosure for LaSalle County Station, Unit Nos. 1 and 2 ML23031A1972023-01-31031 January 2023 Notification of NRC Fire Protection Team Inspection Request for Information, Inspection Report Nos. 05000373/2023011 and 05000374/2023011 IR 05000373/20220042023-01-31031 January 2023 County Station - Integrated Inspection Report 05000373/2022004 and 05000374/2022004 RS-23-003, Constellation Energy Generation, LLC, Summary of Changes to Quality Assurance Topical Report, NO-AA-10, and Decommissioning Quality Assurance Program, NO-DC-102023-01-31031 January 2023 Constellation Energy Generation, LLC, Summary of Changes to Quality Assurance Topical Report, NO-AA-10, and Decommissioning Quality Assurance Program, NO-DC-10 2024-01-05
[Table view] Category:Licensee Event Report (LER)
MONTHYEAR05000373/LER-2017-0072017-08-18018 August 2017 Low Pressure Core Spray System Inoperable due to Loss of Cooling, LER 17-007-00 for LaSalle County Station, Unit 1, Regarding Low Pressure Core Spray System Inoperable due to Loss of Cooling 05000374/LER-2017-0032017-08-0909 August 2017 High Pressure Core Spray System Inoperable due to Injection Valve Stem-Disc Separation, LER 17-003-01 for LaSalle County Station, Unit 2 Regarding High Pressure Core Spray System Inoperable due to Injection Valve Stem-Disc Separation 05000374/LER-2017-0042017-07-14014 July 2017 Two Main Steam Safety Relief Valves Failed Inservice Lift Inspection Pressure Test, LER 17-004-01 for LaSalle, Unit 2, Regarding Two Main Steam Safety Relief Valves Failed Inservice Lift Inspection Pressure Test 05000373/LER-2017-0062017-07-14014 July 2017 Low Pressure Core Spray Inoperable due to Minimum Flow Valve Failure in Closed Position, LER 17-006-00 for LaSalle, Unit 1, Regarding Low Pressure Core Spray Inoperable due to Minimum Flow Valve Failure in Closed Position 05000373/LER-2017-0052017-04-18018 April 2017 Manual Reactor Scram Resulting From Feedwater Regulating Valve Failure Causing High Reactor Water Level, LER 17-005-00 for LaSalle County, Unit 1, Regarding Manual Reactor Scram Resulting From Feedwater Regulating Valve Failure Causing High Reactor Water Level 05000373/LER-2017-0042017-04-17017 April 2017 Secondary Containment Inoperable Due to Interlock Doors Open, LER 17-004-00 for LaSalle County, Unit 1, Regarding Secondary Containment Inoperable Due to Interlock Doors Open 05000373/LER-2017-0032017-04-14014 April 2017 Automatic Reactor Scram due to Main Generator Trip on Differential Current During Back-Feed Operations, LER 17-003-00 for LaSalle County Station, Unit 1, Regarding Automatic Reactor Scram due to Main Generator Trip on Differential Current During Back-Feed Operations 05000374/LER-2017-0022017-03-30030 March 2017 High Pressure Core Spray System Declared Inoperable due to Cooling Water Strainer Backwash Valve Stem-Disc Separation, LER 17-002-00 for LaSalle, Unit 2, Regarding High Pressure Core Spray System Declared Inoperable due to Cooling Water Strainer Backwash Valve Stem-Disc Separation 05000374/LER-2017-0012017-03-24024 March 2017 Manual Reactor Scram due to Turbine-Generator Run-Back Caused by Stem-Disc Separation in Stator Water Cooling Heat Exchanger Inlet Valve, LER 17-001-00 for LaSalle County, Unit 2 Regarding Manual Reactor Scram due to Turbine-Generator Run-Back Caused by Stem-Disc Separation in Stator Water Cooling Heat Exchanger Inlet Valve 05000373/LER-2017-0012017-02-0808 February 2017 Reactor Core Isolation Cooling System Inoperable Longer than Allowed by the Technical Specifications due to Low Suction Pressure Trips, LER 17-001-00 for LaSalle County, Unit 1, Regarding Reactor Core Isolation Cooling System Inoperable Longer than Allowed by the Technical Specifications due to Low Suction Pressure Trips 05000374/LER-2016-0012016-04-18018 April 2016 Secondary Containment Inoperable Due to Interlock Doors Open, LER 16-001-00 for LaSalle County, Unit 2, Regarding Secondary Containment Inoperable Due to Door Interlock Doors Open 05000373/LER-2016-0012016-04-11011 April 2016 Secondary Containment Inoperable due to Reactor Building Ventilation Damper Failure, LER 16-001-00 for LaSalle County, Unit 1 & 2, Regarding Secondary Containment Inoperable Due to Reactor Building Ventilation Damper Failure 2017-08-09
[Table view] |
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 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.
3. LER NUMBER 2. DOCKET NUMBER - 00
PLANT AND SYSTEM IDENTIFICATION
LaSalle County Station Unit 1 is a General Electric Boiling Water Reactor with 3546 Megawatts Thermal Rated Core Power.
The affected system was the Division 1 Low Pressure Core Spray (LPCS) system, one of the stand-by emergency core cooling systems (ECCS) credited for emergency injection into the reactor pressure vessel (RPV). The LPCS system is designed to provide sufficient cooling to the reactor core to prevent excessive fuel cladding temperatures following any break in the nuclear system piping. The affected support system was the diesel generator (DG) cooling water system, which provides cooling to the LPCS room equipment and the LPCS pump motor, from the Division 1 DG cooling water pump ODGO1P.
CONDITION PRIOR TO EVENT
Unit(s): 1 Reactor Mode(s): 1 Date: June 22, 2017 Time: 2043 CDT Mode(s) Name: Power Operation Power Level: 100 percent
DESCRIPTION
On June 22, 2017, the Unit 1 Low Pressure Core Spray (LPCS) system was declared inoperable due to loss of a supporting system for corner room area cooling and loss of motor cooling. The common (Division 1) diesel generator (DG) cooling water pump received an automatic trip signal while being secured. The LPCS pump remained in standby during the event. This condition could have prevented LPCS, a single train safety system, from performing its design function. The NRC was notified of the event on June 23, 2017, via emergency notification system (ENS) report 52821.
Prior to the condition the station was preparing to shut down Unit 1 for a planned maintenance outage. The Division 1 residual heat removal (RHR) pump had been shut down, and its corner room fan had been verified to be secured. As neither Unit 1 nor Unit 2 required the use of the common DG cooling pump, the ODGO1P control switch was taken to the STOP position at the 1PM01J panel. When the switch was taken to the STOP position, the automatic trip light lit and 1PM01J-A215 0 DG trouble alarm annunciated. Operations re-verified that the associated pumps and fans were not required to be running and took the ODGO1P control switch to the NORMAL AFTER STOP position and the ODGO1P pump restarted. This operation was performed to ensure operability of the pump and minimize risk. Troubleshooting identified that the most likely reason for the malfunction of the ODGO1P pump breaker was a contact fault of either the OHS-DG001A control switch or the 1VY01C control relay.
Troubleshooting was performed, and both the control relay and the hand switch were replaced. Correct operation of the control circuit and breaker was verified, and the equipment was returned to operable status.
CAUSE
The most likely causes of the event were intermittent binding of the contact carriers internal to the switch or an intermittent failure of the control relay that contains the contact that provides the automatic start of the ODGO1P pump. The analysis of various potential failures of other components in the control logic did not identify any other component failures with the potential to cause the same type of behavior. Based on the review of the troubleshooting and failure analysis, both suspected failure modes were addressed by component replacements.
2017 007 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 used to impose an information collection does not display a currently valid OMB control nutter, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
3. LER NUMBER 2. DOCKET NUMBER - 00
REPORTABILITY AND SAFETY ANALYSIS
The required action of Technical Specifications (TS) 3.5.1, "ECCS — Operating" was entered on June 22, 2017 at 2043 CDT when the condition was identified, and the LPCS system was determined to be inoperable. The TS limiting condition of operation (LCO) was exited on June 23, 2017 at 1357 CDT when the station transitioned Unit 1 to Mode 4 in support of the planned maintenance outage L1M22. Troubleshooting, associated component maintenance, and system testing was completed on June 24, 2017 at 1518 CDT.
This component inoperability is reportable in accordance with 10 CFR 50.73(a)(2)(v)(D) as an event or condition that could have prevented fulfillment of the safety function of structures or system that are needed to mitigate the consequences of an accident.
This condition could have prevented the LPCS system, a single train safety system, from performing its design function. There was minimal safety consequences associated with the condition since other required emergency safety systems remained operable, there were no actual demands for Unit 1 LPCS, and safety margins were maintained.
This condition was determined to be a safety system functional failure (SSFF) as defined in accordance with NEI 99-02, Regulatory Assessment Performance Indicator Guideline.
CORRECTIVE ACTIONS
Corrective actions were taken to replace the OHS-DG001A control switch and the 1VY01C control relay during troubleshooting.
PREVIOUS OCCURRENCES
A review of station Licensee Event Reports and corrective action program (CAP) data for the past three years, related to switch failures, identified the following similar instance:
ICES 322935 — LaSalle Unit 1, Reactor Building Ventilation Fan Tripped During Fan Swap (April 29, 2016) Operations personnel were performing a fan swap on Reactor Building Ventilation (VR), when the fan tripped shortly after starting.
The consequence was loss of one ventilation fan; however, there are three fans in the train where only two fans are needed for normal operation. The failure was due to switch stop contacts stuck closed in the Control Room. The cause was SBM-style switch stop contacts stuck closed giving a stop signal when the switch was taken to start. The switch was replaced with a new one and tested successfully. Actions to prevent recurrence were determined to be not needed because the switch has been reliable and there has not been a failure of the SBM switch component in over fifteen years on any of the twelve VR supply/exhaust fans, and the device's preventative maintenance was in alignment with station expectations.
COMPONENT FAILURE DATA
Manufacturer: General Electrical Company (G080) Device: Diesel Generator 0 Cooling Water Pump Hand/Control Switch Component ID: OHS-DG001A, Model: Q16SBMD4C42P1F1P1 (SBM) 2017 007