Washington's blog has been doing a great job at nuclear coverage, which potentially is the biggest thing of our lives. Maybe not, but maybe so. 2.5 million pounds of uranium and some plutonium all gathered in one completely out of control area. About 8 pounds are needed to make a nuclear bomb. This will not blow up like a nuclear bomb, but release of radiation could be way more than a nuclear bomb or ten or maybe a hundred, I don't know. And if you don't know, then you don't know either.
This Euro source shows data that about 5% or the radioactivity is Cesium, 95% Iodine. That is important because Iodine can be protected with Potassium Iodine (research it, don't just take it) and Iodine goes away fairly quickly, 50% every 8 days. Cesium takes 30 year to "go away", so of all the Cesium being released now, in 60 years, 25% will still be around.
Cesium is absorbed by the human muscle, and becomes a dangerous internal emitter, until excreted from the body, which happens in maybe 10 to 100 days on average, but some might stick around, and even 1 particle could cause a cancer.