[en] The survey of crack growth on PWR reactor primary circuit pipings is the subject matter of the Aquitaine-1 Program. - This program includes an experimental part on piping elements made of stainless steel AISI 316, L scale 1/4 of primary pipings. These pipings are subject to cyclic variations of cold pressure, then to 290⁰C in water, utilizing a specific test loop. At 290⁰C the pressure variations are between the atmosphere and 160 bars at 4 cycles/hr. With the above conditions the experimental part constitutes a realistic approach to phenomena pertaining to defects propagation in actual operating conditions. A first phase consisted of characterizing the material. The speed of cracking was determined on test-piece CT in the various environment conditions: air 20⁰C, air 320⁰C, water 320⁰C. Furthermore, an evaluation of the influence of the cycling frequency on that speed had been made. (Auth.)