Rpm Meter Quotes

Despite international calls for Chernobyl to be decommissioned at once, it endured a very gradual demise. On October 11th, 1991, just five years after the Unit 4 explosion, there was a third major accident at the plant, this time at Unit 2. Prior to the event, the Unit had been taken offline following another accident - this time a fire in its section of the turbine hall, which had broken out during minor turbogenerator repair work. After extinguishing the blaze, the generator had been isolated and its turbine coasted down to about 150 rpm when a faulty breaker switch closed, reconnecting it to the grid. The turbine rapidly sped up to 3000 rpm in under 30 seconds, then, according to a 1993 report by the U.S. Nuclear Regulatory Commission, “the influx of current to TG-4 overheated the conductor elements and caused a rapid degradation of the mechanical end joints of the rotor and excitation windings. A centrifugal imbalance developed and damaged generator bearings 10 through 14 and the seal oil system, allowing hydrogen gas and seal oil to leak from the generator enclosure. Electrical arcing and frictional heat ignited the leaking hydrogen and seal oil creating hydrogen flames 8 meters high, and dense smoke which obstructed the visibility of plant personnel. When the burning oil reached the busbar of the generator it caused a three-phase 120,000-amp short circuit.”265