Modern reactor plant designs use deep-layered protection to prevent the release of radioactive materials into the environment.
Deep-layered protection is achieved by combining several sequential and independent levels of protection that must fail before radiation can cause damage to the public or the environment. When designing such nuclear reactor systems, a series of physical barriers are envisaged, as well as a combination of active, passive and intrinsic safety characteristics, so that physical barriers to the proliferation of nuclear materials are effective.
Due to the combination of active and passive safety systems on generation III and III+ reactors, autonomy in case of accidents can be achieved for up to 72 hours. In other words, in the event of a major accident, the reactor can cool down for 3 days without the intervention of operational personnel.
In addition, during the development of modern reactors, the probabilities of beyond-design accidents are analyzed. For example, the buildings of some reactor plants can be designed in such a way as to withstand hurricanes of the third category.
