Can I get a summary of all the nuclear reactors having troubles in Japan

[Electric Monk]

and the extent of the problem at each?

I'm getting a bit confused by the various scattershot reports.

Also, I've heard Japan has 55 nuclear sites, but does that mean 55 power plants each (some?) with multiple reactors, or 55 reactors total?

Yes, I've tried googling, with mixed results. That's part of the reason for my confusion.