A Radiation Estimation Method for use in the Initial and Intermediate Stages of a Nuclear Accident

The rapidly evolving series of events experienced during the Fukushima Dai-ichi nuclear power plant accident highlights the need for a capability for rapidly defining the evacuation zones needed to protect people from the radiation release. To address this need, the University of Tokyo and Mitsubishi Heavy Industry (MHI) recently began a 3-year research program, sponsored by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT). In addition to the organizations from the Japan, this research program is being conducted in collaboration with a coalition of international partners from the United States (US) and European Union (EU) who are leading researchers in the fields of atmospheric dispersion and estimation of source term parameters for airborne contaminants. The quantity of radiation released during the accident is critical to an accurate determination of a reasonable evacuation zone. The goal of this effort is to develop a Source Term Estimation (STE) methodology capable of rapidly determining the radiation release rate should a similar accident at a nuclear power station occur again. The STE system being developed will utilize all available relevant observations. These include measurements from stationary monitoring posts, aircraft, and vehicles that were collected both at the initial and intermediate stages of the nuclear power plant accident. The first year (2012) involves collaborative kickoff meetings with the international coalition that will help inform the technology development. In the 2nd year (2013) the system will be further refined and validated. The integration of the STE capability will be conducted in the 3rd year (2014). The final target for this project is the development of techniques that will improve the emergency response system for a nuclear accident and can be used to revise the regulatory guide for nuclear safety assessment. In this presentation we will introduce results from a Verification and Validation(V&V) study of our STE method.