In September 2017 a large pollution of ruthenium 106 was detected, first over Eastern Europe then over Asia and North America. Those detections occurred on the “Ring of 5” informal network and on the “International Monitoring System” (IMS) of the “Comprehensive Nuclear-Test-Ban Treaty Organisation”. This particular isotope is monitored on a daily basis by the IMS as its only sources could either be a nuclear weapon test or an accident at a nuclear facility (it was detected after Tchernobyl for example).
In this study, we simulated this pollution using two very different models, FLEXPART a Lagrangian model, and CHIMERE an Eulerian model. Using the same scenario we compared the two approaches with all available measurements for this incident. The figure presents the plume of simulated ruthenium 106 a few days after release (left CHIMERE, right FLEXPART). We also tested the different implemented transport scheme in CHIMERE and their effect on reducing the numerical diffusion in a real uncontrolled pollution case.