Probabilistic studies for safety at lower cost

In reactor safety studies, probabilistic estimation improves risk assessment thanks to integration. of uncertainty factors in failure mechanisms trough random variables.. New numerical techniques, such as First Order Reliability Method and Second Order Reliability Method allow fast and efficient calculations for specific cases (opposite of Monte Carlo methods, more general but requiring huge calculation means). A major point of possible safety/cost optimisation is reactor maintenance, in particular for vapor generators follow-up. An EDF modelization resulted in COMPROMIS computer code which optimizes their maintenance. (D.L.). 3 figs., 1 photo