Can the nuclear safety concept "Defense In Depth" improve the security of industrial and technological activities in France?

Abstract : Since the 60's, the "Defense In Depth" concept has provided a key approach to formalize and improve nuclear safety in power plants. It consists of deploying technical and organizational barriers and lines of defense structured on five protection levels. Protection levels represent the safety goals related to prevention and control of abnormal operations, mitigation of severe accidents and radiological consequences of significant external releases of radioactive materials. After the AZF disaster occurred in Toulouse the 21st September 2001, the Parliamentary Inquiry of the French government enounced numerous recommendations to improve the security of industrial and technological activities and, among them, the use of "Defense In Depth" concept and Probabilistic Risk Analysis (PRA). This paper presents a study financed by the French government on the capability to transpose this concept into the French policy to improve industrial and technological security and control. The authors present the underlying theoretical basis of the "Defense In Depth" concept in nuclear safety, its legislation framework and control. They discuss the legal and technical means to engage and to solve the problems that could occur for its implementation into industry.