2. Safety principles and practices

Safety principles and practices have gradually emerged from over 50 years' experience in the nuclear industry, and are now the subject of international consensus, even if their detailed application is still a matter of national sovereignty. Starting from the general objective of maintaining containment, plant design is based on defense-in-depth, the spirit of which can be summed up as follows: each level of defense must be designed to avoid, if possible, calling on the next level, while taking into account the effects of failures at the previous level. This means that, whatever measures are taken to prevent errors, incidents and accidents, it must be assumed that they do occur, and the means must be put in place to deal with them and limit their consequences. Where necessary, safety-critical equipment is doubled up, so that a single failure cannot cause the loss of essential functions....