1. Problems associated with severe accidents in nuclear reactors

Severe accidents in nuclear power plants are unlikely events, but they have far-reaching consequences, since they can lead to significant radioactive releases outside the plant, with the risk of exposure for the general public and contamination of the environment. Despite all the measures taken to reduce the probability of such events occurring, three major nuclear accidents have occurred in the history of civil nuclear power: firstly, the accident involving the pressurized water reactor at Three Mile Island (USA) in 1979, the accident involving the RBMK (pressurized water reactor using graphite as a moderator) reactor at Chernobyl (Ukraine) in 1986, and more recently, the accident involving the boiling water reactors at Fukushima Daiichi (Japan) in 2011.

These accidents, which led to partial or total meltdown of the reactor core and, in the case of the two most...