The IRSN’s earliest assessments of the Fukushima accident's consequences for the terrestrial environment in Japan

In 2011 the Institute for Radiological Protection and Nuclear Safety (IRSN) conducted several assessments of atmospheric radioactive releases due to the Fukushima Daiichi NPP accident on Mar 11, 2011 and of their impact on Japan's terrestrial environment. They were based on the IRSN's emergency management tools and on the abundant information and technical data gradually published in Japan. According to these assessments, the main release phase lasted from Mar 12, 2011 to 25, 2011 and impacted Japanese land in two events, the first on March 15 and March 16, in which the main radioactive deposits were formed, and the second from March 20 to March 23, which was less significant. According to IRSN estimates, in the absence of protection, the doses due to exposure to the radioactive plume during the atmospheric release phase may have been potentially higher for people who remained in coastal areas up to several tens of kilometers north and south of the damaged plant.