Real-Time Calculation of the Accident at the Fukushima-1 NPP (Japan) Using the Sokrat Code

Some results of a numerical analysis of the serious unanticipated accident at the Fukishima-1 NPP are presented. The analysis was performed in March 2011 as part of the support given by Rosatom, including in making decisions about possible protection of the population in the Far East region of Russia. On the basis of calculations performed with the SOKRAT code, the state of the core during the first week and the possible reasons of the explosions in the first three power units were evaluated: the core of all three reactors melted and in course of its degradation from 950 to 1100 kg of hydrogen could have been formed followed by the formation of a burning mixture. The computational data on hydrogen emission due to oxidation of the melt by steam agree with experiments performed with the QUENCH and PARAMETR facilities. It can be asserted 1.5 years after the accident that post-accident studies confirm the main results of the real-time calculations.