Experiences from the ARGOS user group nuclear emergency exercise

Area of Science:

• Nuclear Safety and Security
• Environmental Radiation
• Emergency Response Planning

Background:

• The Accident Reporting and Guiding Operational System (ARGOS) is a critical decision support tool for nuclear and radiological emergency preparedness and response (EPR).
• A global user group of government agencies involved in EPR utilizes ARGOS.
• Regular exercises are essential for maintaining proficiency and evaluating decision support systems.

Purpose of the Study:

• To train ARGOS users and enhance their knowledge of the system's capabilities.
• To compare model outputs and protective action recommendations from different participants.
• To identify factors influencing response variability in simulated nuclear and radiological incidents.

Main Methods:

• A 2020 desktop exercise was conducted for the ARGOS user group.
• Two hypothetical accident scenarios were simulated: a floating nuclear power plant (NPP) and the Loviisa NPP.
• Participants used ARGOS to model consequences, estimate source terms (where applicable), and recommend protective actions.

Main Results:

• General agreement on plume direction and extent was observed for the floating NPP scenario.
• Greater variation in results was noted for the Loviisa NPP scenario, influenced by differences in participant-provided source terms.
• Dispersion modeling, source term estimation, and protective action recommendations showed areas of both consensus and divergence.

Conclusions:

• Participation in the exercise increased users' knowledge and understanding of ARGOS for nuclear and radiological emergency planning and response.
• The exercise highlighted the importance of accurate source term information in consistent emergency response modeling.
• Decision support tools like ARGOS are valuable for enhancing preparedness and response capabilities in nuclear emergencies.