NEA Reduction Of Severe Accident Uncertainties (ROSAU) Project

The NEA ROSAU project aims at reducing knowledge gaps and uncertainties associated with severe accident progression. Following the Fukushima Daiichi accidents, there have been systematic re-evaluations carried out worldwide of assumed accident initiators, the resultant plant response to severe accident conditions, and finally operator actions for coping with and terminating severe accident progression. Based on several gap analyses, two areas of severe accident progression have been identified where additional knowledge is needed and where uncertainties could be reduced. These areas are:

Within the ROSAU programme, a total of eleven tests in the above two categories are planned. The experiments will be conducted at the Argonne National Laboratory, USA, with up to 300 kg of molten prototypic material, at temperatures up to about 2400 °C. In addition to the experiments, a parallel analytical activity will be carried out to refine and validate models and codes for each test category to form the technical basis for extrapolating the findings from the experiments to plant conditions.


Belgium, Czech Republic, Canada, France, Japan, Korea, Sweden, and the United States

Project Period

June 2019 to May 2024


EUR 8.6 million

Related links

Last updated: 6 December 2019