This is the same post as below only with a different header. I thought it worth duplicating in light of the latest from Japan. Above
These four videos from Fairewinds' Chief Nuclear Engineer, Arnie Gundersen are the latest from fairewinds.com/updates page and should be viewed in reverse order. They are both very insightful and very informative, but please pay them a visit and please bookmark their pages to keep abreast of the situation.
And this fellow too.