INCEFA-PLUS Project: Review of the test programme and main results

Abstract

INCEFA-PLUS (INcreasing Safety in NPPs byCovering gaps in Environmental Fatigue Assessment) project characterized environmentally assisted fatigue of stainless steels in light water reactor environments. During this project more than 200 fatigue tests have been carried out in different laboratories across Europe in air and water environment. Most tests were performed on a single batch of 304L, an austenitic stainless steel alloys employed in NPPs. The tests addressed the effects of strain amplitude, hold time periods, material roughness and mean strain/stress on fatigue endurance. A limited number of tests was carried out on other batches of 304L and on X6 CrNiTi 18 10, a Ti stabilised steel used in VVERs. Additionally, activities on the effects of mean stress under strain control, testing at reduced environmental fatigue correction factor Fen, and different applications of hold time as well as biaxial fatigue tests have been carried out. The data obtained has been collected and standardised in an online environmental fatigue database MatDB.

Characterization of Austenitic Stainless Steels with Regard to Environmentally Assisted Fatigue in Simulated Light Water Reactor Conditions

“…For tests in air, holds were added at 6000 cycle intervals starting from the 6000th cycle for strain range 0.3% and 1000 cycle intervals starting from the 1000th cycle for 0.6%. Preliminary analysis including Phase II tests ( [40,42], confirmed in Section 3.1.3) suggested that there was no observable effect of hold times for the tested conditions, although beneficial effects of hold time on fatigue life have been reported by the AdFaM (Advanced Fatigue Methodologies) project [13].…”