First, I want to recommend the videos by Fairewind associates by Arnie Gundersen, where he explains details and facts about radioactivity and what happens at Fukushima. (It is also useful to Google Arnies name as he frequently comments in various TV channels, and those links are very recent).
Arnie Gundersen has been working 39 years with nuclear power engineering. He was involved in working with the Harrisburg catastrophe, and based on the information available, and because of his knowledge and skills he makes very accurate descriptions about what is going on at Fukushima.
The other source is a way to keep you updated from moment to moment about the advents at Fukushima. I use to read the twitterstream mentioning Fukushima, radiation, nuclear, tepco and IAEA, in Blogs of war http://blogsofwar.com/nuclear/ . If you use that and check sources you will be almost instantly updated of what is happening in Japan.