3. Probabilistic safety assessment

Having used probabilistic assessments for certain external hazards, such as aircraft crashes, and then to assess the probability of total failure of specific functions, it was natural to develop this technique for the whole plant. These studies were launched in France in the 1980s, and led to an initial set of results for 900 and 1,300 MWe reactors and . Studies were initially limited to assessing the probability of core meltdown.

These studies were the first in the world to explore and quantify the risks in reactor shutdown situations and for long periods after the onset of accident situations.

They are now evolving to take account of the risks associated with fires in installations, to calculate the probability of significant releases into the environment, and to implement new calculation tools....