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| Report date | Site | Event description | |
|---|---|---|---|
| 05000341/LER-2017-004 | 9 October 2017 | Fermi | On August 10, 2017, it was determined that inadequate procedural guidance for determining operability for ventilation support systems was being utilized. The Residual Heat Removal (RHR) switchgear and pump rooms have ventilation systems to maintain operability of the equipment in the rooms. Fermi 2 procedures had directed personnel to declare the supported equipment in the rooms inoperable due to nonfunclionality of the ventilation systems only if the room temperature exceeded the operability limit. Following discovery, a review of the RHR switchgear and pump room ventilation systems for the past three years was performed. The review identified multiple instances where the ventilation systems were nonfunctional and should have resulted in entry into applicable Technical Specifications (TS). Many of these instances resulted in operations or conditions prohibited by TS, since TS Required Actions were not completed within the Completion Times for restoration of affected equipment and plant shutdown. In addition, one instance was identified where the plant configuration was such that it could have prevented the fulfillment of the safety function to remove residual heat following a design basis accident. An engineering evaluation of this specific instance was performed and verified that the plant remained within its analyzed design basis. All other instances maintained one fully operable division of heat removal equipment such that no loss of safety function existed. There were no radiological releases associated with this event. The safety significance was determined to he very low. The cause of the event was inadequate procedural guidance. Immediate actions were taken to provide interim guidance related to the procedure. Corrective actions to revise the affected procedure have been completed. |
| 05000341/LER-2017-003 | 21 July 2017 | Fermi | On May 22, 2017 at 05:10 am (EST), while placing Division 2 Residual Heat Removal Service Water (RHRSW) in service for biocide treatment of the Division 2 Residual Heat Removal (RI IR) Reservoir, the Division 2 RI IRSW Flow Control Valve (FCV) (El 1 50F068B) failed to fully open. Troubleshooting discovered the direct cause was failure of the anti-rotation bushing stem key. The apparent cause was system operating conditions (high vibration) resulting in the failed tack welds. Previous troubleshooting on an indication issue on May 5, 2017 for the RHRSW FCV was inadequate, and did not identify the failure of the anti-rotation key. As a result, the RHRSW FCV was returned to service at 2:50 pm on May 7, 2017, and subsequently failed on the next on-demand stroke at 5:10 am on May 22, 2017. Seventeen similar Motor Operated Valves (MOVs) were inspected and no MOVs exhibiting the symptoms observed on the E1150F068B prior to the failure of the anti-rotation key were found, and all anti-rotation devices were found to be intact. The Past Operability determination for 131150E068B found that the MOV was unable to perform its design basis functions from May 3. 2017 at 5:48 am, when the RI IRSW FCV was last successfully stroked under dynamic conditions, through May 24. 2017 at 4:04 pun, when the RI IRSW FCV was returned to service. The Division I RI-IRSW was available throughout the event except on two occasions. Division 1 of RHRSW was declared inoperable for Mechanical Draft Cooling Tower (MDCT) Nozzle Cleaning activities on May 9, 2017 from 8:41 am to May 9, 2017 at I I :18 pm. Division I of RI IRSW was again declared inoperable for IVIDCT Nozzle Cleaning activities on May 11, 2017 at 8:35 am through May 11, 2017 at 10:01 pm. The as found condition of the Division 2 RHRSW FCV is a condition prohibited by Technical Specification 3.7.1 and reportable under 10 CFR 50.73 (a)(2)(i)(13) "Operation or Condition Prohibited by Technical Specifications," and 10 CFR 50.73(a)(2)(v)(13) "Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to: Remove Residual Heat. |
| 05000341/LER-2017-002 | 16 March 2017 | Fermi | On January 19, 2017, a condition was identified that impacted the operability of certain functions associated with the High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC) systems under low reactor pressure conditions. HPCI and RCIC both have automatic and manual actuation functions to inject water into the reactor vessel. HPCI and RCIC also both have an automatic function (i.e. Level 8 trip signal) to prevent injection to the reactor vessel so that water does not reach the steam lines. This Level 8 trip signal comes from instrumentation that is calibrated to be most accurate at normal operating conditions. Under low reactor pressure conditions (i.e. below 600 psig), the high drywell pressure automatic actuation of HPCI and the manual initiation of both HPCI and RCIC are prevented by a Level 8 trip signal such that the affected HPCI and RCIC functions should be considered inoperable per Technical Specifications (TS). This can cause HPCI to also be considered inoperable, which could prevent the fulfillment of a safety function since HPCI is a single train system. Fermi 2 was at a pressure above 600 psig at the time of discovery and, therefore, the condition did not exist. However, a review of past operating conditions identified twelve instances in the past three years where the condition did exist. Based on an engineering analysis, the affected HPCI and RCIC functions are not required to perform a safety function at low reactor pressures; therefore, there was no adverse impact to public health and safety or to plant employees. There were no radiological releases. The cause of the event was an inconsistency between the Fermi 2 TS and the original design and licensing basis of the HPCI and RCIC systems. For corrective actions, Fermi 2 has submitted a license amendment request to clarify the TS. |
| 05000341/LER-2017-001 | 6 March 2017 | Fermi | On January 6, 2017 an Operations Shift Engineer determined that use of the Reactor Protection System (RPS) test box described in station procedures would result in the loss of two RPS reactor scram functions. Technical Specification (TS) 3.3.1.1 requires that RPS instrumentation for Table 3.3.1.1-1 Function 5 for Main Steam Isolation Valves (MSIVs) and Table 3.3.1.1-1 Function 9 for Turbine Stop Valves (TSV) remain OPERABLE. Operations procedures were revised to incorporate the use of the test box in August of 2016. Between September 22 and 23, 2016 the MSIV and TSV procedures were each performed one time using the test box. The failure to recognize the impact of the procedure revisions is considered a human performance error by engineering and operations personnel. The procedures were corrected in January 2017 to remove the use of the RPS test box. Subsequently, on January 7 and 9, 2017, respectively, the procedures for the TSVs and the MSIVs were performed successfully. |
| 05000341/LER-2016-001 | 23 January 2017 | Fermi | At 1514 EST on January 6, 2016, while operating at 100 percent Reactor Thermal Power (RTP), the East and West Turbine Bypass Valves (TBV) automatically opened as expected for 3 minutes and 32 seconds in response to the number one High Pressure Turbine Stop Valve (TSV) drifting from full open to 25 percent open due to an actuator malfunction. Per Technical Specification (TS) Bases 3.3.1.1, TBVs must remain shut while RTP is at or above 29.5 percent to consider all channels of the TSV closure and Turbine Control Valve (TCV) fast closure Reactor Protection System (RPS) functions operable. Reactor Operators lowered RTP to 91.0 percent and at 1518 EST the TBV automatically closed and the TSV closure and TCV fast closure RPS functions were no longer considered inoperable. TS 3.3.1.1 requires that the TSV closure and TCV fast closure RPS functions be operable at or above 29.5 percent RTP. In this event, during the period of time while TBVs were open, reactor power was maintained above 91 percent and the RPS functions were confirmed to be enabled. The actuator malfunction was caused by faulty connectors within the actuator. The faulty connectors were replaced. |
| 05000341/LER-2015-003 | 5 May 2015 | Fermi | On March 19, 2015 at 0702 EST the reactor protection system at Fermi 2 initiated an automatic reactor scram on Oscil ation Power Range Monitor (OPRM) Upscale following the manual trip of the north reactor recirculation pump due to a cooling water leak. The reactor protection system performed as expected and all control rods were fully inserted into the core. Reactor water level reached a low of approximately 126 inches above top of active fuel and was restored and maintained in the normal operating band by the feedwater and control rod drive systems. No safety relief valves actuated and reactor pressure was controlled by the main turbine bypass valves. Plant systems responded to the scram as designed and all reactor parameters were maintained within design limits following the event. The cause of the automatic reactor protection system scram on OPRM Upscale was the neutron flux oscillations following the large core flow reduction and lowering feedwater temperature after the trip of a reactor recirculation pump. This event was documented and evaluated in the Fermi 2 Corrective Action Program. The associated root cause evaluation is in progress and may identify additional corrective actions which will be tracked and implemented by the corrective action program. This event is reportable in accordance with 10 CFR.50.73(a)(2)(iv)(A) as a critical reactor scram. |
| 05000341/LER-2013-003 | 22 January 2014 | Fermi | On November 24, 2013, at approximately 00:01 hours EST, during normal plant operations, the non-safety related Reactor Building Heating Ventilation and Air Conditioning (RBHVAC) system tripped on low steam coil heater temperature. Secondary Containment differential pressure exceeded the Technical Specification (TS) Surveillance Requirement limit of -0.125 inches water column (WC), reaching a maximum of +0.08 inches WC. At 00:04 hours EST, the Standby Gas Treatment System (SGTS) was started and Secondary Containment differential pressure decreased to less than -0.125 inches WC. The RBHVAC system tripped due to lack of steam flow through a heating coil caused by inadequate draining of the downstream steam trap. Investigation revealed the presence of some corrosion and a cracked drain seat in the associated steam drain. The degraded steam drain was then replaced and tested. RBHVAC was returned to normal operation and SGTS was shutdown and returned to standby at 23:46 hours EST on November 24, 2013. Preventive maintenance is being scheduled to inspect, and clean or replace the RBHVAC steam traps and strainers. With Secondary Containment differential pressure exceeding -0.125 inches WC, TS Surveillance Requirement 3.6.4.1.1 was not met and Secondary Containment was declared inoperable. No other degradation of Secondary Containment existed at the time of the event. This event was reported per the guidance of NUREG-1022, Rev. 3, section 3.2.7, as a loss of Safety Function. There were no radiological releases associated with this event. |
| 05000341/LER-2013-002 | 22 October 2013 | Fermi | On August 30, 2013 at approximately 0017 hours, while performing a routine surveillance procedure, Instrumentation and Control (I&C) technicians discovered that a thermocouple was improperly wired which resulted in an inoperable Division I Reactor Core Isolation Cooling (RCIC) area room temperature input to the associated steam line isolation logic. The improper wiring was determined to be in place for approximately 14 days without isolation of the RCIC steam line which is greater than allowed by Technical Specification 3.3.6.1. The event was caused by technicians incorrectly replacing terminal block knife switches on August 16, 2013. Insufficient rigor and was applied by the technicians during concurrent verification activities for interim alterations of the associated isolation circuitry. The thermocouple wiring was promptly corrected, the associated Channel Functional Test was satisfactorily completed at 0145 hours on August 30, 2013, and the equipment was returned to service. The qualifications of the technicians involved were removed until such time as the individuals were re- trained. Re-training on verification practices was conducted with I&C Group personnel. |
| 05000341/LER-2013-001 | 18 March 2013 | Fermi | On January 22, 2013, at approximately 0113 hours EST, during startup of the Reactor Building Heating Ventilation and Air Conditioning (RBHVAC) system, with the Standby Gas Treatment System operating, Secondary Containment pressure went positive for 27 seconds, reaching approximately +0.15 inches of water column (WC). The RBHVAC Center Exhaust Fan discharge damper appears to have opened after the Supply Fan discharge damper opened contrary to design, causing the Secondary Containment pressure increase. The System was returned to normal with two RBHVAC trains running and Standby Gas Treatment System shutdown and in standby. Reactor building pressure stabilized at less than -0.125 inches WC. The causes of this event appear to be delayed operation of the center RBHVAC exhaust fan discharge damper and relay timing out of tolerance for the RBHVAC Center Supply and Exhaust fan dampers. Work Management procedures are being followed to troubleshoot the actuator for the discharge damper and the supply and exhaust fan relay timing. This event has been entered into the Fermi 2 Corrective Action Program. Investigation continues and could result in additional corrective actions. |
| 05000341/LER-2003-003 | 26 November 2003 | Fermi | General Electric Company submitted a 10 CFR 21 notification identifying that they had determined that the stability Option III period based detection algorithm (PBDA) period confirmation adjustable variables (period tolerance and conditioning filter cutoff frequency) may be non-conservative, and recommended that the Average Power Range Monitoi (APRM) Operating Power Range Monitor - . (OPRM) Upscale trip (Technical Specification Limiting Condition for Operation (LCO) 33.1.1, function 2.0 be considered inoperable for plants with a PBDA period tolerance setpoint less than 100 msec, and with a cutoff frequency of greater than 1.0 Hz. All OPRM channels were declared inoperable (but were maintained in a functional and armed condition) on October 2, 2003, because the Fermi-2 OPRM period tolerance was set at 50 msec, and the conditioning filter cutoff frequency was set at 3.0 Hz. Alternate methods to detect and suppress thermal hydraulic instability oscillations were placed into effect in accordance with Technical Specification LCO 33.1.1, Action J. The apparent deficiency was identified by General Electric (the OPRM and reactor vendor) following a July 24, 2003 instability event at Nine Mile Point-2. The Fermi OPRM settings would have been sufficient to identify a wide range of stability transients. Additionally, the operators have been trained to recognize instabilities and to take appropriate actions should an instability occur. The period tolerance and conditioning filter cutoff frequency setpoints were changed and all OPRM channels were declared operable on November 18, 2003. This event has been documented in the Fermi 2 corrective action program. NRC FORM 368 (7.2o01) |
| 05000341/LER-2002-002 | 26 June 2002 | Fermi | As a result of a fire protection program self assessment, on May 2, 2002, Detroit Edison Company determined that a field modification performed on February 19, 2002 invalidated an inherent assumption in the procedure for controlling the plant from the dedicated shutdown panel. Specifically, the motor operator for motor operated valve (MOV) N2000F636, Condenser Hotwell Emergency Makeup Bypass Valve, was rotated 180 degrees to help alleviate an oil leakage problem. Rotating the MOV relocated the motor operator handwheel away from the first floor of the Turbine Building such that operators could not reasonably close the valve without the use of a ladder. Procedure 20.000.18, "Control of the Plant from the Dedicated Shutdown Panel," directs operators to de-energize and manually close N2000F636 to prevent losing Condensate Storage Tank (CST) water inventory to the Hotwell, in case a hot short caused the valve to open. Losing CST inventory threatens the ability to achieve safe shutdown conditions in the event of a fire. Therefore, this condition is reportable under Section 2.F of the Fermi 2 Operating License as a violation of License Condition 2.C.(9). Based on the short delay associated with obtaining a ladder and closing the valve, this condition did not result in any adverse effect on the health and safety of the public. A dedicated ladder has been staged near the valve. Other corrective actions involve the identification of Appendix R components in the plant CECO database, additional training and guidance on dealing with Appendix R components, and periodic verification of the steps in procedure 20.000.18. |