They go on and on about how their system 'automatically' shut down. Blah Blah!
When we did a seismic evaluation, we replaced all the mercury-wetted relays which are notoriously sensitive in earthquakes. Looks like these bad relays shut them down and forced them to the notorious diesel generators. There is some question about how many are actually needed - 1, 3, or 4.
Problems with the transformers or grid switchyards is most likely what will shut down the nuclear plants when we have our earthquake in Ontario. The plants then face the problem of restarting or the 'Black Start' problem.