04-17-2017 | On February 16, 2017, Unit 1 was in Mode 2 for startup at five percent power, and Unit 2 was defueled for a planned refueling outage with movement of irradiated fuel (MIF) in progress. At 0835 CST, both air-lock doors of the Unit 1 reactor building to the chemistry corridor were opened simultaneously for approximately five seconds during personnel ingress. The employee immediately secured both doors in the interlock and notified the Main Control Room. While both interlock doors were open, Technical Specifications (TS) Surveillance Requirement (SR) 3.6.4.1.2 to verify one secondary containment access door in each access opening is closed was not met. Secondary containment was declared inoperable for the period of time that both interlock doors were open. TS 3.6.4.1 Required Action ( RA) A.1 to restore secondary containment to operable status within four hours was entered and exited. TS 3.6.4.1 RA C.1 to immediately suspend MIF in secondary containment was entered and exited. This event is reportable in accordance with 10 CFR 50.73(a)(2)(v)(C) and 10 CFR 50.73(a)(2)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material or mitigate the consequences of an accident. The most probable cause of the interlock failure was the intermittent failure of a circuit board which is designed to prevent more than one door to be open at a time. Previous events and prior causal investigations have indicated degradations in the relays for these circuit cards, and the corrective actions to replace interlock door circuit cards was ongoing at the time this event occurred. The door interlock was satisfactorily tested by maintenance technicians, and the door interlock was returned to service on February 18, 2017. |
---|
|
---|
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 (1--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 and Unit 2 are each a General Electric Boiling Water Reactor with 3546 Megawatts Thermal Rated Core Power. The secondary containment is the reactor building, common to both reactor units, which contains the reactor auxiliary and serving equipment for the two reactors. The secondary containment access doors, or air-locks, provide a means for personnel and equipment to enter or exit the reactor building without breaching secondary containment integrity.
CONDITION PRIOR TO EVENT
Unit(s): 1 / 2 Reactor Mode(s): 2 / 5
DESCRIPTION OF EVENT
Event Date: February 16, 2017 Event Time: 0835 CST Mode(s) Name: Startup/Refueling Power Level: 5 percent/0 percent On February 16, 2017, Unit 1 was in Mode 2 for plant startup at 5 percent power, and Unit 2 was defueled for a planned refueling outage with movement of irradiated fuel (MIF) in progress. At 0835 CST, both air-lock doors of the Unit 1 reactor building to the chemistry corridor (doors 225 and 226) were opened simultaneously for approximately five seconds during personnel ingress. The employee immediately secured both doors in the interlock and notified the Main Control Room (MCR).
Shift Operations personnel subsequently blocked access until repairs could be made, and MIF activities were immediately suspended.
While both interlock doors were open, Technical Specifications (TS) Surveillance Requirement (SR) 3.6.4.1.2 to verify one secondary containment access door closed was not met. Secondary containment was declared inoperable for the period of time that both interlock doors were open. Reactor building differential pressure, as observed in the MCR, remained less than -0.25 inches vacuum water gauge at all times. TS 3.6.4.1 Required Action (RA) A.1 to restore secondary containmdnt to OPERABLE status within four hours was entered and exited. TS 3.6.4.1 RA C.1 to immediately suspend MIF in secondary containment was entered and exited.
CAUSE OF EVENT
The most probable cause of the interlock failure was the intermittent failure of a circuit board which is designed to prevent more than one door to be open at a time. Similar previous interlocked door circuit board failures have been identified, through formal failure analysis, to have been caused by degraded relays integral to the circuit board. This interlock had used an upgraded style of circuit board that had been installed less than a week earlier on February 10, 2017. The door was satisfactorily tested by Mechanical Maintenance, but the failure could not be reproduced. A causal investigation for an event in 2016 identified relays on the circuit cards as the specific cause of the failures. Corrective actions from the 2016 investigation had been ongoing to upgrade interlock door circuit cards with ones that had improved relays.
REPORTABILITY AND SAFETY ANALYSIS
This event is reportable in accordance with 10 CFR 50.73(a)(2)(v)(C) and 10 CFR 50.73(a)(2)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material or mitigate the consequences of an accident. These doors are ground elevation personnel air-lock between the common diesel generators' corridor to the Unit 2 reactor building. The secondary containment access doors, or air-locks, provide a means for personnel and equipment to enter or exit the reactor building without breaching secondary containment integrity. This is necessary so that the negative pressure can be maintained.
The safety significance of this event was minimal, since the reactor building to outside differential pressure remained negative throughout the period that the secondary containment was inoperable. The secondary containment was inoperable for approximately five seconds, which was significantly less than the four-hour Completion Time to restore secondary containment to operable status allowed by TS 3.6.4.1 Required Action A.1.
2017 004 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 dsplay 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 - 00 004 The function of the secondary containment is to contain, dilute, and hold up fission products that may leak from the primary containment following a Design Basis Accident (DBA). A technical evaluation determined that the inadvertent simultaneous opening of secondary containment doors for less than 30 seconds are bounded by the existing drawdown analysis and dose calculations and will not result in a failure of a safety system function needed to control the release of radioactive material to the environment. The time that both doors were simultaneously opened for this event was approximately five seconds, which is & 2 Secondary Containment Air-lock Doors.") This event did not result in the reactor enclosure differential pressure dropping below the design bases set point of -0.25 inches vacuum water gauge. Both the inner and outer doors were promptly closed by station personnel, which ended the event. This event did not involve any kind of door or air-lock material condition preventing door closure. Additionally, both the inner and outer doors were closed by normal expected means and were capable of remaining closed as designed.
The computed dose for EC 396711 was based on the door opening during the 780 second time period prior to Standby Gas Treatment (SBGT) system drawdown and filtration. This discounts the initial 120 seconds of an event where no release takes place, in accordance with calculation L-003068, "Re-Analysis of Loss of Coolant Accident (LOCA) Using Alternative Source Terms.
The approximate five second opening of the secondary containment doors is bounded by calculation L-003068. Should an event occur, in which both secondary containment doors were open simultaneously for 30 seconds or less, it would result in a potential dose increase of approximately 3.85 percent. The 3.85 percent decrease in margin is inconsequential in comparison to the 10 CFR 100 regulatory limits.
EC 396711 also evaluated the pressure impact on the secondary containment and the ability of the SBGT system to achieve the TS required negative pressure. The results of the evaluation show SBGT would restore secondary containment pressure within three minutes which is well below the 15 minute maximum drawdown time required by TS.
Based on the short duration of door opening (approximately five seconds), no material condition preventing door closure or maintaining the doors closed, and attendance by knowledgeable personnel who closed the doors immediately, the secondary containment safety function was maintained.
CORRECTIVE ACTIONS
The door was satisfactorily tested by Mechanical Maintenance and returned to service on February 18, 2017. Numerous additional informal interlock door checks wer.e performed by the subject matter expert following the return to service of the door interlock, and the interlock circuitry performed as expected without issue.
Corrective actions from the previous causal investigations had been ongoing to upgrade interlock door circuit cards with ones that had improved relays. This door set used a circuit card from the improved lot supplied by the vendor that had been installed on this door set on February 10, 2017. The station continues to work with the circuit card vendor to evaluate the failure analysis and determine if additional actions are warranted.
PREVIOUS OCCURRENCES
The interlock that failed had the new style circuit card with improved relays replaced less than a week prior to this event as an action created from a previous failure. Corrective actions from previous events had been ongoing to upgrade interlock door circuit cards with ones that had improved relays. These corrective actions were the result of causal investigations with previous events as follows.
On January 18, 2017, Unit 1 was in Mode 1 at 100 percent power, and Unit 2 was in Mode 1 at 100 percent power with MIF in progress. At 2056 hours0.0238 days <br />0.571 hours <br />0.0034 weeks <br />7.82308e-4 months <br /> CST, both air-lock doors of the Unit 2 reactor building 710-foot elevation three-way air-lock opened simultaneously for approximately five seconds during personnel ingress. The most probable cause of the interlock failure was 2017 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.
- 00 the intermittent failure of the relays on the door controller circuit card based on previous history with these circuit boards.
Previous events and prior causal investigations have indicated degradations in the relays for these circuit cards, and the corrective actions to replace interlock door circuit cards was ongoing at the time this event occurred. The controller circuit card was replaced, which restored the interlock functionality on January 19, 2017.
On February 17, 2016, Unit 2 was in Mode 1 at 100 percent power and Unit 1 was in Mode 5 for a refueling outage with no fuel movements or operation with the potential to drain the reactor vessel (OPDRV) in progress. At 1035 hours0.012 days <br />0.288 hours <br />0.00171 weeks <br />3.938175e-4 months <br /> CST, both air-lock doors of the Unit 2 Chemistry Lab corridor to Unit 2 reactor building were open at the same time for approximately five seconds.
The cause was failure of the relays on the door controller circuit card. The controller circuit card was replaced, which restored the interlock functionality. Corrective actions included determination of the cause of vendor quality issues with the controller circuit card relays and procurement of a more reliable controller circuit card following cause identification of the relay failures from vendor analysis.
On February 17, 2015, Unit 1 was in Mode 1 at 100 percent power and Unit 2 was in Mode 5 for a refueling outage with no fuel movements in progress. Activities involving OPDRVs were in progress in the secondary containment on Unit 2. At 1145 hours0.0133 days <br />0.318 hours <br />0.00189 weeks <br />4.356725e-4 months <br /> CST, it was reported that both air-lock doors between the Unit 1 diesel generator corridor and the Unit 1 reactor building were open at the same time for approximately five to ten seconds. The cause was a failure of a controller circuit card in the door interlock logic. The circuit card was replaced, which restored the interlock functionality. Corrective actions included a cause determination for the premature controller circuit card failures and replacing the card with more reliable models.
On December 12, 2014, both Units 1 and 2 were in Mode 1 at 100 percent power with no fuel movements in progress. At 1324 hours0.0153 days <br />0.368 hours <br />0.00219 weeks <br />5.03782e-4 months <br /> CST, it was reported that both air-lock doors between the Unit 2 diesel generator corridor and the Unit 2 reactor building were open at the same time for approximately ten seconds. The cause was a degradation of the door closure mechanism, and the contributing cause was a less than robust design of the door interlock assembly. Corrective actions from the previous occurrences to identify, procure and install a more robust interlock assembly design were in progress at the time of the event.
Additional corrective actions, including periodic preventative maintenance to inspect, tighten, and replace fasteners as necessary, were in place but did.not preclude this event. This event did not involve a door controller circuitry reliability issue.
On February 18, 2014, Unit 1 was in Mode 5 with fuel moves in progress during a refueling outage, and Unit 2 was in Mode 1 at 100 percent power. At 1820 hours0.0211 days <br />0.506 hours <br />0.00301 weeks <br />6.9251e-4 months <br /> CST, it was reported that both air-lock doors between the Unit 2 diesel generator corridor and the Unit 2 reactor building were open at the same time for approximately three seconds. The cause of the event was degradation of the door closure mechanism and door frame seal. A contributing cause was a less than robust design of the door interlock assembly. Corrective actions from the previous occurrences to identify, procure and install a more robust interlock assembly design were still in progress at the time of the event. Additional corrective actions included creating a periodic preventative maintenance task to inspect, tighten, and replace fasteners as necessary. This event did not involve a door controller circuitry reliability issue.
COMPONENT FAILURE DATA
Manufacturer: Security Door Controls (SDC) Device: UR2-4 Controller Card Component ID: 1695558 2017
3. LER NUMBER
004
|
---|
|
|
| | Reporting criterion |
---|
05000374/LER-2017-001 | 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 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000373/LER-2017-001 | 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 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000374/LER-2017-002 | 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 | 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | 05000374/LER-2017-003 | 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 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000373/LER-2017-003 | 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 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000374/LER-2017-004 | 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 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000373/LER-2017-004 | 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 | 10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | 05000373/LER-2017-005 | 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 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000373/LER-2017-006 | 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 | 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | 05000373/LER-2017-007 | 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 | 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident |
|