Safety confirmation of emergency core cooling system for boiling water reactor

For the quantitative evaluation of the present safety evaluation model in the case of postulated loss-of-coolant accidents in a boiling water reactor, study on the reflood in the reactor core is going on by the use of an apparatus newly contrived, eighteen-degree-sector test apparatus (ESTA). This apparatus mocks up a part, axially actual and radially 18 degrees, of the interior components of the pressure vessel. The results of experiments with this apparatus have clarified that the quantity of the reactor core spray water in the emergency core cooling system effectively contributes to the cooling of the core, consequently, the safety evaluation model has sufficient maintainability. (author)