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Report date | Site | Event description | |
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05000265/LER-2015-001 | 30 March 2015 | Quad Cities | On March 5, 2015, at approximately 1640, the watertight door for the Unit 1 High Pressure Coolant Injection (HPCI) room was found open with no person in attendance. In this condition, the door is not able to perform the flood protection function. With no person in attendance the door would not be shut to prevent internal flood water from entering the Unit 1 HPCI room. This condition would result in the inoperability of equipment in the room it is designed to protect from flooding. The construction of the adjacent Unit 1 and Unit 2 HPCI rooms provides no flood barrier between the two rooms. Therefore, a condition that results in flood protection being nonfunctional to one HPCI room also has an effect on the opposite Unit HPCI. The Unit 1 HPCI watertight door being found open, with no one in attendance, results in the unplanned inoperability of the Unit 2 HPCI, since the Unit 2 HPCI is required to be operable by Technical Specifications in Mode 1. The Unit 1 HPCI was not required to be operable since Unit 1 was in Mode 5. Therefore, this Licensee Event Report is being submitted in accordance with 10 CFR 50.73 (a)(2)(v)(D) for an event or condition that could have prevented fulfillment of a safety function. |
05000265/LER-2012-003 | 14 June 2012 | Quad Cities | On April 18, 2012, at 1511 hrs, while at low power conditions after refueling outage Q2R21, an automatic reactor scram occurred on Unit 2 due to high reactor pressure. The pressure increase occurred during post-modification testing on the main generator automatic voltage regulator (AVR) which had been upgraded during refueling outage Q2R21. The testing included a generator load reject, which was in progress when the pressure transient occurred. There were no complications during the reactor scram and subsequent turbine trip, and all systems functioned as required. Operators performed required actions safely and in accordance with procedures and training. The cause of the automatic scram was due to high reactor pressure created by the load rejection associated with the main generator voltage regulator testing, coincident with unresponsive opening demand of turbine control valves (TCVs) that impacted the turbine bypass valves (TBVs) ability to control reactor pressure. Since the digital electro hydraulic control (DEHC) system design lacked the required Intercept (IV) EHC shutoff valves, this resulted in low EHC pressure and caused the TCVs to be unresponsive. Unit 1 was unaffected by the event and remained at 100% power. Corrective actions included evaluating the impact of the event on the operability of the TBVs, and applying a Minimum Critical Power Ratio (MCPR) Operating Penalty (TS 3.7.7) when reactor power is between 25% and 50%. Future corrective actions include development of a hardware/software modification to the DEHC system to correct the design deficiency. The safety significance of this event was minimal. This event is reportable (Unit 2) per 10 CFR 50.73(a)(2)(iv)(A), which requires the reporting of any event or condition that resulted in manual or automatic actuation of the reactor protection system (RPS), including reactor scram; (Units 1 and 2) 10 CFR 50.73(a)(2)(i)(B), which requires the reporting of any operation or condition which was prohibited by the plant's Technical Specifications; and (Units 1 and 2) 10 CFR 50.73 (a)(2)(v)(C), which requires the reporting of any event or condition that could have prevented the fulfillment of the safety function of structures or systems needed to control the release of radioactive material. |