Semantic search
Report date | Site | Event description | |
---|---|---|---|
05000482/LER-2017-002 | 31 May 2017 | Wolf Creek | On April 5, 2017, Wolf Creek Generating Station (WCGS) was in Mode 1 at 100 percent power. During evaluation of protection for safety-related equipment from the damaging effects of tornados, WCGS personnel determined that safety-related fuel oil transfer lines inside the Diesel Generator Building could be damaged if tornado generated missiles struck the non-safety related truck connections to these transfer lines. As these safety-related transfer lines are required to supply fuel to the Emergency Diesel Generators (EDGs) from the fuel oil storage tank, Operations declared both of the EDGs inoperable. On April 5, 2017, at 1632 Central Daylight Time, an 8- hour, non-emergency report to the Nuclear Regulatory Commission (NRC) (reference NRC Event Notification Number 52666) was made in accordance with 10 CFR 50.72. Compensatory measures were implemented consistent with Enforcement Guidance Memorandum (EGM) 15-002, "Enforcement Discretion for Tornado-Generated Missile Protection Noncompliance." The EDGs were then declared operable but non-conforming. These tornado missile vulnerabilities existed since the original plant construction. Immediate compensatory measures included verification that the severe weather procedures were up-to-date, ensuring that Operations personnel were current on their training to these procedures, and implementing measures to heighten station awareness until the vulnerabilities had been corrected. These vulnerabilities have now been permanently eliminated. |
05000482/LER-2015-004, Incorrect Decision Results in Two Containment Isolation Valves being in a Condition Prohibited by Technical Specifications | 14 September 2015 | Wolf Creek | On May 5, 2015, it was discovered that the motive force (air supply) was not removed for two containment shutdown purge valves as required by Technical Specification 3.6.3, "Containment Isolation Valves." The motive force was restored to allow the performance of procedure STS KJ-001A, "Integrated Diesel Generator and Safeguards Actuation Test - Train A," on April 26, 2015. After performance of procedure STS KJ-001A, the motive force was not removed for the two containment shutdown purge valves. The plant entered Mode 4 on April 28, 2015 at 0144 Central Daylight Time (CDT). Upon discovery, the air supply valves for the two containment shutdown purge valves were locked closed, removing the motive force. The cause of the event was the decision to only track components listed in the manual Locked Component Log during plant start-up, allowed a mode change with components out of position. The safety significance of the event was low as each penetration flow path had a redundant valve that was closed with the motive force removed. |
05000482/LER-2015-002, Two Control Room Air Conditioning Trains Inoperable Due to Failure to Meet Surveillance Requirement | 26 August 2015 | Wolf Creek | From January 3, 2013, through August 13, 2013, the Conditions and Required Actions of limiting condition for operation (LCO) LCO 3.7.11, LCO 3.0.3 and LCO 3.0.4 were not met. On April 16, 2015, an apparent cause evaluation on Condition Report (CR) 92274, "Application of TS SR 3.0.1," identified the potential that the acceptance criteria in procedures STS PE-010A/B, "Control Room NC System Flow Rate Verification (A/B) Train," may not have been met when the acceptance criteria was revised on January 3, 2013 from > 18,360 cfm and information determined that the prior performances of STS PE-010A/B did not meet the new acceptance criteria. Additionally, procedure STS PE-010B was not performed until July 8, 2013 and procedure STS PE- 010A was not performed until August 13, 2013. The apparent cause of this event is the information in Operability Evaluation OE GK-12-017, which addressed a separate issue on the same equipment, enabled control room operators and engineering personnel to rationalize the assumption that the change to the acceptance criteria was bounded and did not impact the ability to meet SR 3.7.11.1. |
05000482/LER-2015-003, Manual Reactor Trip due to High Steam Generator Level Transient at Low Power | 1 July 2015 | Wolf Creek | On May 3, 2015 at 1021 Central Daylight Time (CDT), Wolf Creek Generating Station (WCGS) was at approximately 25% power during startup from Refueling Outage 20. The 'C' steam generator received a Hi-Hi level signal while the Reactor Operator was manually transferring feedwater control from the Main Feedwater Regulating Valve (MFRV) bypass valves to the MFRVs. This resulted in a main turbine trip, feedwater isolation, and auxiliary feedwater actuation. A manual reactor trip was initiated at 1022 CDT. The root cause was the lack of a reliable and consistent standardization between the operating crews to control the transfer of the steam generator feedwater flow between the MFRV bypass valves and MFRVs and a sense of urgency by the control room operators. The event is bounded by analyses as reported in the Wolf Creek Generating Station (WCGS) Updated Safety Analysis Report (USAR) Section 15.2.7, "Loss of Normal Feedwater Flow. |
05000482/LER-2015-001, Personnel Error Causes Two Inoperable Residual Heat Removal Trains | 25 March 2015 | Wolf Creek | On January 28, 2015, the nightshift operations crew implemented a clearance order to support planned maintenance on two Residual Heat Removal (RHR) System valves that included closing valves EJHV8716A and EJHV8809A. At 0534 hours on January 28, 2015, Condition C of Limiting Condition for Operation (LCO) 3.5.2 was entered upon determining that less than 100% of the Emergency Core Cooling System (ECCS) flow equivalent to a single OPERABLE ECCS train was available with valve EJHV8716A closed. Entry into LCO 3.0.3 in accordance with Required Action C.1 was made on two separate occasions. Action was taken to restore valves EJHV8716A and EJHV8809A to the open position and exit LCO 3.0.3. The licensed operators involved with the preparation and implementation of the clearance orders did not recognize that current plant conditions could not support the proposed activity. The individuals involved with this event had their qualifications removed until remediation occurred. Red switch boxes have been placed on the control boards in the control room on the valves in procedure AP 26C-004, "Operability Determination and Functionality Assessment," Section A.16 that can cause an entry into LCO 3.0.3. |
05000482/LER-2002-003 | 28 June 2002 | Wolf Creek | On May 8, 2002, at 5:07 p.m., Wolf Creek experienced an automatic actuation of the Reactor Protection System (RPS) including an automatic reactor trip due to low water level in the "D" steam generator (SG). This actuation occurred following the closure of the "D" SG main feedwater regulating valve (FRV) during surveillance testing. When the FRV closed, "D" SG level decreased below the reactor trip setpoint of 23.5 percent, initiating a reactor trip. The unit received a feedwater isolation and auxiliary feedwater actuation (both motor and turbine driven) because of the low-low SG levels. All control rods fully inserted, and the RPS and the Engineered Safety Features (ESF) Systems performed as expected. The cause of the FRV closure was the failure of a Westinghouse 7300-series manual controller card for the "D" SG FRV. The failed controller card was replaced. The safety significance of this event is low. This event is bounded by the current licensing basis analyses as reported in Wolf Creek Generating Station (WCGS) Updated Safety Analysis Report (USAR) section 15.2.7 "Loss of Normal Feedwater Flow." All safety related equipment performed as expected. There were no adverse effects on the health and safety of the public. |
05000482/LER-2002-002 | 17 June 2002 | Wolf Creek | On April 24, 2002, while in Mode 4, Wolf Creek Nuclear Operating Corporation (WCNOC) personnel completed surveillance procedure STS BB-004, "RCS Water Inventory Balance." A calculational (rounding) error resulted in the conclusion that the Reactor Coolant System (RCS) (EIIS system code AB) unidentified leakage was within the Technical Specification (TS) limit of 1.0 gpm. The unidentified leakage was actually 1.091 gpm, or .091 gpm above the TS limit. On April 25, 2002, Wolf Creek Generating Station (WCGS) entered Mode 3 from Mode 4 contrary to TS Limiting Condition of Operation (LCO) 3.0.4. This specifies that the plant cannot change modes when an LCO is not met. The calculational error made in STS BB-004 was not recognized until after the mode change. When the error was recognized, TS 3.4.13, "RCS Operational LEAKAGE," Condition A, was entered. The source of the leakage was identified and corrected. On April 26, 2002, the leak rate was 0.31 gpm, and Condition B of TS 3.4.13 was exited. This event is reportable per 10 CFR 50.73(a)(2)(i)(B) as a violation of the plant's Technical Specifications. The root cause of this event was inadequate procedural guidance for performing RCS leakage calculations. No impact on personal, nuclear, or radiological safety resulted from this event. |