Covastol Program

In 1976 the French Commissariat a l'Energie Atomique (Department of Nuclear Safety), the commission of the European Communities (Ispra Joint Research Centre) and Framatome set up a joint committee to direct a research program with a task of developing a method of assessing pressure vessel fast fracture probability and formulating the requisite digital computer programs. The whole program proceeding from this agreement is managed by a joint board including the three partners. The method used in the present work involves the development of physical models based on an understanding of the failure modes and expressing the conventional concepts of fracture mechanics in a probabilistic form: the fatigue crack growth rate, calculated for conditions of cyclic loading, the initiation of unstable crack propagation, and the possibility of crack arrest. The analysis therefore requires the statistical expression of the factors and parameters which appear in the expressions of the law of crack growth and of toughness, and also those which are used in the calculation of the stress intensity factor