Wikipedia has a pretty good summary

Wikipedia article on Fukushima I Incident

Note that Wikipedia article itself is the "polished summary". The linked references go into much more detail, and the Article Discussion Page will provide more insight, as well.

As noted on the page, the Wikipedia article will evolve as news comes in.
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A signal mirror should backup a radio distress signal, like a 406 MHz PLB (ACR PLB) (Ocean Signal PLB)