Keywords:Fukushima Daiichi Nuclear Power Plant, Severe Accident, Meltdown, SAMPSON
The accident at the Fukushima Daiichi unit 3 has been studied extensively in the last years but still large uncertainty exists on the final state of the core and debris state. Such uncertainties reflect on the difficulty to create strategies for debris removal. In current Japanese national project we have organized all the available information in order to clarify the known condition of the power plant. Based on such information a best estimate current condition of the plant has been proposed in which MCCI played a major role in the accident determining the large hydrogen generation for the explosion of Unit 3 and Unit 4. Based on the analysis of the temperature measurements at the plant a relatively large amount of debris is supposed to remain in the vessel. The estimated results are confirmed with the analysis of the SAMPSON code.