Multi-model ensemble analysis of JRODOS atmospheric dispersion models for nuclear emergency planning

The Real-Time On-Line Decision Support System (JRODOS) is operationally used worldwide to support off-site nuclear emergency management. This study presents a new JRODOS module for emergency planning that combines the JRODOS statistical module, which samples meteorological conditions over extended periods for a given site, with a dedicated post-processing workflow to analyze the outputs of the multiple atmospheric dispersion models integrated in JRODOS. Using the full emergency calculation chain, it derives early-phase protective action areas and applies user-defined thresholds to identify higher-probability zones. The approach is demonstrated for three representative nuclear power plant sites with contrasting terrain, and the resulting site- and model-dependent action areas are compared to assess the influence of model choice on planning outcomes.