PHYSICAL PROTECTION AND NUCLEAR SAFETY- SYNERGIES AND DIFFERENCES

For the objectives of nuclear safety, various sets of accidental sequences are set up and taken into account in safety studies of a facility. The aim of these studies is to give confidence that its operation presents a sufficiently low-level risk, deemed acceptable for personnel, the public and the environment. Accidental sequences could come from failure of a piece of equipment, internal hazards (missiles from inside the containment area, results of piping breaks, turbogenerator bursting, load dropping, fire, internal flooding etc…) or external hazards (earthquake, aircraft crashes, industrial environment, floods etc). Another set of accidental sequences could occur when considering the State’s Design Basis Threat and it has to be checked if these sequences are already covered by the nuclear safety case or if the operator has to take additional provisions to protect the facility. Many of the provisions taken to cope with accidental sequences coming from the failures and hazards above could be useful to cope with accidental sequences coming from sabotage. Some of the sequences coming from these other sets of accidental sequences, which are not studied as safety concerns, have to be analysed. Potential conflicting requirements, resulting from nuclear safety and physical protection considerations, should be carefully analysed to ensure that they do not jeopardize nuclear safety or nuclear security, including emergency conditions. More generally it is shown that there are fundamental principles, most of them must be present in the safety field and the physical protection field namely the defence in depth concept. This paper shows, with various examples how the nuclear safety provisions contribute significantly to the protection against sabotage of nuclear facilities.