Nuclear data for severe accident analysis and decommissioning of nuclear power plant

Three-dimensional nuclide inventory and decay heat distributions at the time of the nuclear accident in Fukushima-Daiichi power plants were evaluated on the basis of the detailed burnup calculation with JENDL-4.0. Total decay heat of the unit-2 after the accident was compared with the decay heats obtained by simple evaluation formulas used in the safety analyses of ECCS and in the severe accident analyses. As a result, applicability of the formulas to the Fukushima-Daiichi accident was quantitatively clarified. At the end, we briefly introduce our recent activities on the development of the basic database for decommissioning of light water reactors. (author)