Safety tests file

The design and operation of nuclear power plants is governed by strict and clearly defined regulations designed to ensure their safety in all circumstances. Since the first nuclear reactors were commissioned, the basic safety principles and the corresponding practical requirements have constantly evolved and been enhanced, benefiting from operating experience feedback from reactors around the world (about 500 production reactors currently in service). Reactor safety has from the outset been built around the 'defense in depth' concept, which aims to prevent melting of the core and radioactive releases into the environment. It can be summarized as follows: over and above all the measures taken to prevent accidents, the principle that accidents do occur has to be accepted. We then assess their consequences and take steps to contain them at the level of severity at which they occur. (authors)