Analyses of core melt and re-melt in the Fukushima Daiichi nuclear reactors

Analyses are performed of the first core melt behavior of the Unit 1, Unit 2 and Unit 3 reactors of Fukushima Daiichi Nuclear Power Station on 11-15 March 2011 as well as the re-melt (melt again) behavior in another chaotic period of 19-31 March 2011. Analyses are based on a measured data investigation and a simple model calculation.