On May 26, 2017, a Control Room Emergency Filter System ( CREFS) supply fan damper was discovered to be partially open, limiting air flow to less than the Technical Specifications (TS) required flow. The configuration of the supply fan damper is to be fully open when the corresponding supply fan is in service. Cooper Nuclear Station ( CNS) Operations personnel declared CREFS inoperable at 1105 and entered TS Limiting Condition for Operation 3.7.4, Condition A.
Subsequent investigation revealed that the damper control arm was correctly positioned, however the T-handle for the control arm was overtightened causing the control arm to bend upward which mispositioned the damper from full open to partially open. The control arm for HV-AD-AD1021B was replaced and post work testing performed to ensure the correct position of the damper. CREFS was declared operable at 0432 on May 27, 2017.
To prevent recurrence, CNS will modify the design of the both CREFS damper control arms and the means of securing in position to prevent control arm bending.
There were no safety consequences associated with this condition. |
|
|---|
Category:Letter
MONTHYEARML23334A2012024-01-0303 January 2024
Issuance of Amendment No. 274 Revision to Technical Specifications to Adopt TSTF-551, Revision 3, Revise Secondary Containment Surveillance Requirements
ML23311A1122023-11-0909 November 2023
Project Manager Assignment
ML23311A2082023-11-0909 November 2023
Reassignment of U.S. Nuclear Regulatory Commission Branch Chief in the Division of Operating Reactor Licensing for Plant Licensing Branch IV
IR 05000298/20230032023-11-0202 November 2023
Integrated Inspection Report 05000298/2023003
IR 05000298/20234012023-11-0101 November 2023
Cyber Security Report 05000298/2023401 Public
ML23264A8052023-10-11011 October 2023
Issuance of Amendment No. 273 Revision to Technical Specifications to Adopt TSTF-580, Revision 1, Provide Exception from Entering Mode 4 with No Operable RHR Shutdown Cooling
ML23233A1882023-09-0505 September 2023
Regulatory Audit Plan in Support of Relief Request RC3-02 Regarding Drywell Head Bolting
IR 05000298/20243012023-09-0101 September 2023
Notification of NRC Initial Operator Licensing Examination 05000298/2024301
IR 05000298/20230052023-08-21021 August 2023
Updated Inspection Plan for Cooper Nuclear Station (Report 05000298/2023005)- Mid Cycle Letter
IR 05000298/20230022023-08-0808 August 2023
Integrated Inspection Report 05000298/2023002
IR 05000298/20234022023-08-0303 August 2023
NRC Security Inspection Report 05000298/2023402
ML23214A2742023-08-0303 August 2023
Nuclear Station - Notification of Inspection (NRC Inspection Report 05000298/2023004) and Request for Information
IR 05000298/20234202023-08-0101 August 2023
Security Baseline Inspection Report 05000298/2023420
ML23173A0862023-06-26026 June 2023
Information Request for the Cybersecurity Baseline Inspection, Notification to Perform Inspection 05000298/2023401
IR 05000298/20230102023-05-17017 May 2023
Biennial Problem Identification and Resolution Inspection Report 05000298/2023010
IR 05000298/20234032023-05-0404 May 2023
Security Baseline Inspection Report 05000298/2023403
ML23129A2822023-04-20020 April 2023
Submittal of Revision 31 to Updated Safety Analysis Report
ML23102A0282023-04-19019 April 2023
U.S. Nuclear Regulatory Commission Presentation at the May 8, 2023, Brownville Village Meeting
IR 05000298/20230012023-04-17017 April 2023
Integrated Inspection Report 05000298/2023001
ML23060A1582023-03-0808 March 2023
Design Basis Assurance Inspection (Programs) Inspection Report 05000298/2023001
IR 05000298/20220062023-03-0101 March 2023
Annual Assessment Letter for Cooper Nuclear Station Report 05000298/2022006
ML23041A1622023-02-10010 February 2023
Licensed Operator Positive Fitness-for-Duty Test Request for Additional Information
IR 05000298/20220042023-01-30030 January 2023
Integrated Inspection Report 05000298/2022004
IR 05000298/20220112022-12-23023 December 2022
License Renewal Phase 4 Inspection Report 05000298/2022011
ML22286A2072022-11-30030 November 2022
Issuance of Amendment No. 272 Revision to Technical Specifications to Adopt TSTF-554, Revision 1, Revise Reactor Coolant Leakage Requirements
IR 05000298/20220032022-10-27027 October 2022
Integrated Inspection Report 05000298/2022003
ML22304A0052022-10-26026 October 2022
Surveillance Capsule Location (Re-insertion Into the Reactor Vessel)
IR 05000298/20223022022-10-20020 October 2022
NRC Initial Operator Licensing Examination Approval 05000298/2022302
ML22276A1562022-10-0505 October 2022
Notification of Commercial Grade Dedication Inspection 05000298/2023011 and Request for Information
IR 05000298/20224022022-09-29029 September 2022
NRC Security Inspection Report 05000298/2022402 (Full Report)
IR 05000298/20220052022-08-18018 August 2022
Updated Inspection Plan for Cooper Nuclear Station (Report 05000298 2022005)
IR 05000298/20223012022-08-10010 August 2022
NRC Examination Report 05000298/2022301
IR 05000298/20220022022-07-28028 July 2022
Integrated Inspection Report 05000298/2022002
ML22200A2772022-07-21021 July 2022
Correction to Proposed Inservice Testing Alternative RS-01, Revision of Error in Safety Evaluation
ML22152A1232022-07-18018 July 2022
Issuance of Amendment No. 271 Request for Exception from Certain Primary Containment Leak Rate Testing Requirements
IR 05000298/20224012022-06-29029 June 2022
Security Baseline Inspection Report 05000298/2022401
IR 05000298/20224032022-06-28028 June 2022
Security Baseline Inspection Report 05000298/2022403
IR 05000298/20220102022-06-16016 June 2022
Triennial Fire Protection Inspection Report 05000298/2022010
ML22140A1612022-06-0808 June 2022
Proposed Inservice Inspection Alternative RR5-01 Revision 1
ML22147A1122022-06-0101 June 2022
NRC Initial Operator Licensing Examination Approval 05000298/2022301
ML22111A1382022-05-13013 May 2022
Proposed Inservice Testing Alternative RS-01, Revision 0
IR 05000298/20220012022-04-28028 April 2022
Integrated Inspection Report 05000298/2022001
IR 05000298/20224042022-04-13013 April 2022
Material Control and Accounting Program Inspection Report 05000298/2022404 - (Public)
ML22084A6032022-04-0404 April 2022
Notification of NRC Evaluations of Changes, Tests and Experiments Inspection 05000298/2022002 and Request for Information
ML22090A2892022-04-0101 April 2022
John Larson'S Invitation to Participate in the 8th Nuclear Regulatory Commission'S Workshop on Vendor Oversight
ML22045A0012022-03-31031 March 2022
Proposed Inservice Inspection Alternative RI5- 02 Revision 3
IR 05000298/20210062022-03-0202 March 2022
Annual Assessment Letter for Cooper Nuclear Station (Report 05000298/2021006)
IR 05000298/20210042022-01-24024 January 2022
Integrated Inspection Report 05000298/2021004
ML21350A0582021-12-21021 December 2021
Withdrawal of an Amendment Request
ML21340A2362021-12-20020 December 2021
Issuance of Amendment No. 270 Adoption of Technical Specifications Task Force Traveler TSTF-582, Revision 0, RPV WIC Enhancements
2024-01-03
[Table view]
Category:Licensee Event Report (LER)
MONTHYEAR05000298/LER-2016-0012017-09-27027 September 2017
De-Energized High Pressure Coolant Injection Auxiliary Lube Oil Pump Caused by Relay Failure Results in Loss of Safety Function and a Condition Prohibited by Technical Specifications, LER 16-001-01 for Cooper Nuclear Station Regarding De-Energized High Pressure Coolant Injection Auxiliary Lube Oil Pump Caused by Relay Failure Results in Loss of Safety Function, a Condition Prohibited by Tech Specs, and a 10 CFR Part 21 Report
05000298/LER-2017-0042017-08-17017 August 2017
Torus to Drywell Vacuum Breaker Failure to Indicate Full Closed Causes Loss of Safety Function, LER 17-004-00 for Cooper Nuclear Station Regarding Torus to Drywall Vacuum Breaker Failure to Indicate Full Closed Causes Loss of Safety Function
05000298/LER-2017-0052017-08-17017 August 2017
Traversing In-core Probe In-shield Limit Switch Mounting Failure Results in Common Cause Inoperability of Independent Trains or Channels and Condition Prohibited by Technical Specifications, LER 17-005-00 for Cooper Nuclear Station Regarding Traversing In-core Probe In-shield Limit Switch Mounting Failure Results in Common Cause lnoperability of Independent Trains or Channels and Condition Prohibited by Technical Specifications
05000298/LER-2017-0032017-07-24024 July 2017
Mispositioned Control Room Emergency Filter System Supply Fan Damper Causes Loss of Safety Function, LER 17-003-00 for Cooper Nuclear Station re Mispositioned Control Room Emergency Filter System Supply Fan Damper Causes Loss of Safety Function
05000298/LER-2017-0022017-04-27027 April 2017
Valve Test Failures Result in Condition Prohibited by Technical Specifications and a Loss of Safety Function, LER 17-002-00 for Cooper Nuclear Station Regarding Valve Test Failures Result in Condition Prohibited by Technical Specifications and a Loss of Safety Function
05000298/LER-2017-0012017-04-0505 April 2017
Residual Heat Removal Minimum Flow Valves OUt of Position Results in Loss of Safety Function and Condition Prohibited by Technical Specifications, LER 17-001-00 for Cooper Regarding Residual Heat Removal Minimum Flow Valves Out of Position Results in Loss of Safety Function and Condition Prohibited by Technical Specifications
05000298/LER-2016-0082017-01-0505 January 2017
Purchase and Installation of Incorrect Actuator Results in a Condition Prohibited by Technical Specifications, LER 16-008-00 for Cooper Nuclear Station Regarding Purchase and Installation of Incorrect Actuator Results in a Condition Prohibited by Technical Specifications
05000298/LER-2016-0072016-12-19019 December 2016
Isolation of Shutdown Cooling due to Relay Maintenance Results in a Loss of Safety Function, LER 16-007-00 for Cooper Nuclear Station Regarding Isolation of Shutdown Cooling due to Relay Maintenance Results in a Loss of Safety Function
05000298/LER-2016-0062016-12-19019 December 2016
High Vibration on Control Room Emergency Filter System Fan Results in Inoperability and Loss of Safety Function, LER-16-006-00 for Cooper Nuclear Station Regarding High Vibration on Control Room Emergency Filter System Fan Results in Inoperability and Loss of Safety Function
05000298/LER-2016-0042016-11-22022 November 2016
Closure of Multiple Main Steam Isolation Valves due to High Flow Signal, LER 16-004-00 for Cooper Nuclear Station Regarding Closure of Multiple Main Steam Isolation Valves due to High Flow Signal
05000298/LER-2016-0032016-11-0909 November 2016
Scaffold Construction Places Plant in a Condition Prohibited by Technical Specifications, LER 16-003-00 for Cooper Nuclear Station RE: Scaffold Construction Places Plant in a Condition Prohibited by Technical Specifications
05000298/LER-2016-0022016-06-27027 June 2016
De-Energized High Pressure Coolant Injection Auxiliary Lube Oil Pump Caused By Light Bulb Failure Results in Loss of Safety Function, LER 16-002-00 for Cooper Regarding De-Energized High Pressure Coolant Injection Auxiliary Lube Oil Pump Caused By Light Bulb Failure Results in Loss of Safety Function
NLS2015063, Retraction of Licensee Event Report 2014-005-00, Lube Oil Leak Results in a Potential Condition Prohibited by Technical Specifications and a Potential Loss of Safety Function.2015-06-0909 June 2015
Retraction of Licensee Event Report 2014-005-00, Lube Oil Leak Results in a Potential Condition Prohibited by Technical Specifications and a Potential Loss of Safety Function.
ML13149A1722013-05-26026 May 2013
E-mail from Micheal Mulligan to R.Guzman, Pilgrim Evacuation Plan Broken During Blizzard Nemo and Unenforced by the Nrc.
NLS2013015, Special Report, Offgas Treatment System Charcoal Adsorbers Out of Service2013-01-29029 January 2013
Special Report, Offgas Treatment System Charcoal Adsorbers Out of Service
NLS2008058, LER 08-S01-00 for Cooper Regarding Temporary Suspension of Security Measures Due to Tornado Warning2008-08-0505 August 2008
LER 08-S01-00 for Cooper Regarding Temporary Suspension of Security Measures Due to Tornado Warning
2017-09-27
[Table view] |
Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S.
Affairs, NEOB-10202, (3150-0104), 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 required to respond to, the information collection.
Cooper Nuclear Station 05000- 298 NUMBER NO.
PLANT STATUS
Cooper Nuclear Station (CNS) was in Mode 1, Power Operations, 100 percent power, at the time of discovery; i.e., May 26, 2017.
BACKGROUND
The Control Room Emergency Filter System (CREFS) [El IS:JH] provides a protected environment from which control room personnel can safely operate the plant following an uncontrolled release of radioactivity, hazardous chemicals, or smoke. CREFS maintains the Control Room Envelope (CRE) at a positive pressure with respect to the adjoining areas.
The safety related function of CREFS includes a single high efficiency air filtration system for emergency treatment of outside supply air and a CRE boundary that limits the inleakage of unfiltered air. The system consists of a prefilter, a high efficiency particulate air filter [El IS:FLT], an activated charcoal adsorber [EIIS:ADS] section, a supply fan [EIIS:FAN], an emergency booster fan, an exhaust booster fan, and the associated ductwork [EIIS:DUCT], valves [EIIS:V] or dampers [EllS:DMP], doors [EIIS:DR], barriers, and instrumentation.
The CREFS is a standby system. Upon receipt of an initiation signal, CREFS automatically switches to the emergency bypass mode of operation to minimize infiltration of contaminated air into the CRE.
CNS Technical Specifications (TS) 3.7.4 requires one supply fan to be operable to support CREFS operability.
EVENT DESCRIPTION
On May 26, 2017, at approximately 0321, CNS Operations personnel questioned air flow and differential pressure in the main control room. Subsequently, CREFS supply fan damper, HV-AD-AD1021B, was discovered to be partially open limiting air flow. The configuration of HV-AD-AD1021B is to be fully open when its corresponding supply fan, CREFS supply fan 1B, is in service. CREFS flow rate testing was conducted and determined actual air flow was 802 cubic feet per minute (cfm), less than the TS required flow of 810 cfm. Based on this information, Operations personnel declared CREFS inoperable at 1105 and entered TS Limiting Condition for Operation (LCO) 3.7.4, Condition A, to restore CREFS to Operable within a completion time of seven days.
Further investigation revealed that the control arm for HV-AD-AD1021B was correctly positioned in the open notch to position the damper open, however the control arm had been bent at both notches changing the position of the damper from full open to partially open.
control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
Cooper Nuclear Station - 003 -00 2017
3. LER NUMBER
In 2012, both CREFS dampers (HV-AD-AD1021A and HV-AD-AD1021B) were modified by adding ground level damper position control arms. Prior to 2012, the system design required operators to secure the damper positions by locking screws at an elevation above ground level requiring ladders or climbing.
Due to safety concerns, the position control arms and associated linkages were installed to reach the damper elevation. This modification installed damper position controls at ground level with open and closed notches in the damper control arms.
Just prior to this event on May 22, 2017, a corrective maintenance work order was implemented which replaced the damper control arms as the original control arms, installed via the 2012 modification, were slightly bent. Prior to completion of this work, the control arms had to be replaced a second time when it was discovered that they had also been bent due to overtightening of the T-handles.
The control arms are supported by unistrut with an open channel below which created a "valley" under the T-handle control arm position securing point. This configuration was intended to prevent control arm motion and correctly position the dampers; however, the configuration did not consider that if the T- handles are overtightened the control arms could bend.
The control arm for HV-AD-AD1021B was replaced and post work testing performed to ensure the correct position of the damper. TS LCO 3.7.4 was exited and CREFS was declared operable at 0432 on May 27, 2017.
Additionally, Operations issued a Standing Order to perform applicable portions of two CREFS surveillance procedures if the CREFS supply fan dampers are manipulated to verify CREFS flow rate and CRE pressure relative to atmosphere. This action is to verify the dampers have not moved due to potential rod movement from the control arm becoming bowed.
BASIS FOR REPORT
CNS is reporting this event under 10 CFR 50.73(a)(2)(v)(D) as a condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. CNS also reported this event to the Nuclear Regulatory Commission Operations Center per Event Notification 52771.
SAFETY SIGNIFICANCE
There were no safety consequences associated with this condition. The potential safety significance of this event was low due to the limited duration the condition existed, the condition only slightly degrading CREFS flow below the operability limit, and the condition had no impact on the CRE boundary. CREFS flow was degraded due to supply fan 1B discharge damper being only partially open, when it was required to be fully open. Actual CREF system flow was 802 cfm, which was slightly below the required flow of 810 cfm. The total duration of inoperability of CREFs due to this condition was approximately 1.5 days, which is less than the seven day TS completion time. This condition did not cause an impact to the safety of the general public, nuclear safety, industrial safety, or radiological safety.
control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
Cooper Nuclear Station - 003 - 00 2017
3. LER NUMBER
CNS subsequently performed an engineering analysis which concluded that the CREFS safety design basis was met. The margin in unfiltered inleakage and filter efficiency provides a high degree of confidence that calculated doses would be below the regulatory limits for control room personnel even with the degraded supply air flow through CREFS supply fan 1B and supply fan damper HV-AD- AD1021B. Furthermore, testing performed May 26, 2017, on the CRE in the emergency pressurization mode showed that CREFS met the administrative limit for positive pressure in the CRE. As such, this event is not considered a Safety System Functional Failure.
CAUSE
The T-handle for damper control arm for HV-AD-AD1021B was overtightened causing the control arm to bend upward, mispositioning the damper.
CORRECTIVE ACTIONS
The damper control arm was replaced and post work testing performed to ensure correct position of the damper.
To prevent recurrence, CNS will modify the design of the CREFS damper control arms and the means of securing in position to prevent bending and will provide for independent verification of position of the damper control arms. This action is being tracked in CNS' corrective action program.
PREVIOUS EVENTS
CNS has submitted the following Licensee Event Reports (LER) in the past five years related to CREFS supply fans. Both events resulted in a loss of safety function.
1. LER 2016-009-00 — On December 7, 2016, the running CREFS supply fan was inadvertently turned off during the conduct of a surveillance procedure. The root cause was attributed to human error.
2. LER 2016-006-00 — On October 23, 2016, CREFS supply fan 'A' experienced high vibration. The root cause was the preventive maintenance strategy was ineffective to ensure shaft to bearing engagement.
