In the days after Japan’s Fukushima nuclear accident began, GlobalPost turned to Arnold Gundersen for an independent view of whether the reactors might melt down. A 39-year veteran of the nuclear industry, Gundersen has worked as a nuclear plant operator and served as an expert witness on the Three Mile Island accident. He is now chief engineer at Fairwinds Associates. Back then, Gundersen said that the evidence suggested the accident was worse than authorities were revealing. This week, his assessment was shown to be accurate when Japan upgraded Fukushima to a 7, the worst possible rating for a nuclear accident. So we contacted Gundersen again to get an update on Fukushima. In the following edited and condensed interview, Gundersen gives his expert view of what might happen, how authorities are handling the accident, and how Fukushima will affect health and the environment.