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Risk Analysis Research Group, Nuclear Safety Research Center
JAEA-Testing 2025-007, 110 Pages, 2026/03
JAEA-Testing-2025-007.pdf:2.57MB
The Japan Atomic Energy Agency's Nuclear Safety Research Center is developing the Level 3 PRA code OSCAAR as part of its research on probabilistic risk assessment (PRA) for nuclear power plant accidents. OSCAAR is a computational code that evaluates the advection, diffusion, and deposition of radioactive materials released into the environment under various meteorological conditions, based on source terms obtained from Level 2 PRA. It can probabilistically assess the radiation doses and health effects to the public caused by these radioactive materials. OSCAAR can account for the dose reduction effects of protective measures implemented during an actual nuclear power plant accident, thereby contributing to the pre-planning of countermeasures and plans to reduce the exposure of residents near nuclear power plants during an accident. This report is a manual for users to create input files and execute the OSCAAR program.
Risk Analysis Research Group, Nuclear Safety Research Center
JAEA-Data/Code 2025-015, 68 Pages, 2026/02
JAEA-Data-Code-2025-015.pdf:2.82MB
The Japan Atomic Energy Agency's Nuclear Safety Research Center is developing the Level 3 PRA code OSCAAR as part of its research on probabilistic risk assessment (PRA) for nuclear power plant accidents. OSCAAR is a computational code that evaluates the advection, diffusion, and deposition of radioactive materials released into the environment under various meteorological conditions, based on source terms obtained from Level 2 PRA. It can probabilistically assess the radiation doses and health effects to the public caused by these radioactive materials. OSCAAR can account for the dose reduction effects of protective measures implemented during an actual nuclear power plant accident, thereby contributing to the preplanning of countermeasures and plans to reduce the exposure of residents near nuclear power plants during an accident. This report is a manual explaining the analysis model used in OSCAAR code version 2.0.
Risk Analysis Research Group, Nuclear Safety Research Center
JAEA-Testing 2025-004, 75 Pages, 2025/10
JAEA-Testing-2025-004.pdf:3.13MB
When a nuclear emergency occurs at a nuclear power plant (NPP), protective actions such as evacuation and sheltering are implemented to reduce radiation exposures to the public around the vicinity areas of the NPP. The necessity of the protective actions should be judged, taking into account the various types of information from the on-site and the off-site with reflecting the drastically change of accident situation. Japan Atomic Energy Agency has developed EXTREME (EXpert support Tool for Responding to a nuclear EMErgency) to enable quick and consistent assessments for supporting decision-makers during the response phase after a nuclear emergency occurred. The tool implements simplified models for assessing accident progression, environmental transport, and radiation doses to the public. This tool is also available as a PC-based graphical user interface (GUI) for easy operation by users. This report describes the usage of the developed support tool, focusing on the GUI configuration and the flow of calculations. It is expected that this support tool will effectively assist decision-makers in making judgments and decisions regarding protective actions during the response phase in a nuclear emergency.
Risk Analysis Research Group, Nuclear Safety Research Center
JAEA-Data/Code 2025-010, 110 Pages, 2025/10
JAEA-Data-Code-2025-010.pdf:4.07MB
When a nuclear emergency occurs at a nuclear power plant (NPP), protective actions such as evacuation and sheltering are implemented to reduce radiation exposures to the public around the vicinity areas of the NPP. The necessity of the protective actions should be judged, taking into account the various types of information from the on-site and the off-site with reflecting the drastically change of accident situation. In such decision making, the impacts to the public and surrounding environment also should be assessed quickly and consistently through the source-term, which including the amount and timing of release of radioactivity, and the contamination of environment by those. However, it is difficult to provide the information needed to decision-making, because those from the on-site and off-site are enormous. Therefore, expertise for the accident process in the on-site and for exposure assessment, and advance preparation for processing this information are indispensable. In this study, to deal with a huge amount of information and provide the basis for decisions on protective actions in a nuclear emergency, an expert support tool EXTREME (EXpert support Tool for Responding to a nuclear EMErgency) for nuclear emergency response was developed. This tool has a function to evaluate a simplified source term based on in-core information and a function to evaluate exposure doses around a facility based on the results of the evaluation. The system also has a PC-based graphical user interface (GUI) for easy operation by users even in an emergency. This report describes the models implemented the EXTREME, the input/output data files needed, and trial calculation results used in these functions.
Risk Analysis Research Group, Reactor Safety Research Division, Nuclear Safety Research Center
JAEA-Data/Code 2024-006, 40 Pages, 2024/07
JAEA-Data-Code-2024-006.pdf:1.92MB
The Risk Analysis Research Group, Reactor Safety Research Division, Nuclear Safety Research Center, Sector of Nuclear Safety Research and Emergency Preparedness, Japan Atomic Energy Agency has been developing OSCAAR, a probabilistic risk assessment program for nuclear facility accidents. OSCAAR has the feature to calculate atmospheric concentrations of radioactive materials using an atmospheric dispersion model. This feature requires the input of meteorological data about wind speed, precipitation rate, atmospheric stability and so on. However, to use numerical weather prediction data created from the Japan Meteorological Agency (JMA) on OSCAAR, it is necessary to convert the data format to match OSCAAR input format in advance. Therefore, we developed GPV2OSC, a pre-processing program for OSCAAR, to create meteorological data converted from JMA weather prediction data format to OSCAAR input format when the target region and period are specified. This report describes the outline and usage of GPV2OSC.