fines in October 1997 when the plant failed technical specifications surveillance guidelines. Specifically, they violated rules that require the Emergency Core Cooling System (ECCS) pump casing and discharge piping high points be vented once every 31 days. The potential safety consequence of the violation affiliated with the second fine was considered "low." As of 2007, the last NRC Escalated Enforcement Action against the Bryon Station came in 2005 when an engineer deliberately falsified surveillance reports to show he had completed work that was incomplete; though the plant could have been fined up to $60,000 the NRC chose not to impose the fine. A small fire occurred at the plant on the morning of February 24, 2006. The fire was confined to the Unit 1 Refueling Water Storage Tank (RWST) heater. Initial attempts to extinguish the fire were unsuccessful, following those attempts a breaker was opened and the heater was allowed to deenergize which extinguished the fire. Units 1 and 2 were operating at 100%, but neither reactor was shut down as a result of the fire. As a result of the fire the plant declared an "unusual event", the least serious of the four categories of emergency declarations by the Nuclear Regulatory Commission. On January 30, 2012, the Byron Unit 2 was shut down and depressurized after a failed insulator in the plant's switchyard caused the loss of one phase to the plant's startup transformers. This caused low voltage conditions on the plant's emergency power buses and also for two of the reactor coolant pumps to trip which caused the plant to shut down. The trip of the plant then caused the other two reactor coolant pumps to trip (as they had been receiving power directly from the main generator) and natural circulation had to be used during the shutdown. When operators discovered the loss of the single phase, they manually tripped the breaker feeding the startup transformers, allowing the emergency diesel generators to start and restore normal voltages to the safety buses. Steam was vented from the non-radioactive, secondary side of the plant to aid in the cooling process while the turbines remained offline. A small amount of radioactive tritium was released into the local environment during the initial venting procedure, but was deemed no threat to the public by the Nuclear Regulatory Commission. A similar insulator failure occurred at Unit 1 on February 29 again affecting the unit's