Project to replace the generator was in progress. Accident occurred when they were rigging out the old generator stator (weighs 500 tons, 2x heavier than the Monticello generator stator). Failure occurred when over the railroad bay and the stator dropped 55 feet. Not sure exactly what failed but you can see in the bottom pictures that the stator rotated ~135 degrees before it landed. Have been told that the impact caused the other unit to trip – a check of the NRC website indicates that both are offline, but can’t confirm anything beyond that. Rumor is that the impact could be felt several miles away. Here are MEMEBR AREA photos of the move before and after the rigging failure. The generator and beams fell 55 feet to the Turbine building ground floor.
And pictures of it after it the support broke.
UPDATED on 4/5/13
ANO U1 entered into their refueling outage week before last. They planned to replace the 690 ton Generator Stator. The plan was to install jacks on the generator pedestal and lift the stator and casing into a Carriage and move it to the Train Bay. The carriage carrying the stator was to slide over the train bay, perform a 90 degree turn and subsequently be lowered onto the Goldhofer below. It was when the carriage assembly started its 90 degree turn when the large rails the carriage was moving upon folded up and resulting in load drop. The drop was approximately 32 feet. The rails used are about the same size as the ones used for the SGR. The rails straddled both units exciters & generators and had an overall length of about 120 feet or more. The rails were supported from underneath in the Train Bay. The entire assembly was approximately the same size as a SGR rig. As of last night ANO did not have any idea why it happened. Just below the turbine deck adjacent to the Train Bay is both units Non 1E switchgear along with Offsite Power Supply Feeds. The collapse totally destroyed U1 switchgear and resulted in loss of decay heat and auto start of the diesels. U2 did not initially suffer switchgear damage, however the collapse was so violent that U2 turbine tripped from it. The front standards of the turbines are at opposite ends of the Train Bay. About 10 minutes after U2 tripped the offsite transformer(SU3) feeder breaker catastrophic failed resulting in loss of offsite power and unit 2 going onto diesels. As of midnight last night both units remained on EDG power with no immediate time when normal power restored.
