DIFFUSION SITUATION PREDICTION SYSTEM

PROBLEM TO BE SOLVED: To provide a diffusion situation prediction system for diffusate in which the diffusion situation of diffusate from a diffusion source can be predicted more accurately while regarding a practical aspect important.SOLUTION: A diffusion situation prediction system 10A for diffusate comprises a weather data/diffusate input unit 11, an airflow site data calculation unit 12 and a diffusion site data calculation unit 13. The weather data/diffusate input unit 11 inputs thereto weather data including the wind direction, wind velocity and stability on the target date/time in which radioactive substances are diffused from a diffusion source and the quantity of radioactive substances discharged at that time in a computation area including a target spot where the diffusion source is present. The airflow site data calculation unit 12 calculates airflow site data at intervals of a predetermined time for a predetermined period of time. The diffusion site data calculation unit 13 temporally continuously calculates diffusion site data of radioactive substances by using the obtained airflow site data. On the assumption that the time of disaster occurrence in which radioactive substances are discharged from the diffusion source is deviated at every predetermined time during a predetermined period of time, the airflow site data calculation unit 12 and the diffusion site data calculation unit 13 calculate the diffusion site data at the disaster occurrence time in each deviation.