Properties and IASCC susceptibility of austenitic stainless steel 08X18H10T

A study on an irradiated titanium stabilised 08X18H10T stainless steel from Loviisa NPP absorber element bottom end was initiated in 1999. The aim was to characterise the changes in mechanical properties and the susceptibility to IASCC in VVER environments by laboratory tests. Results showed that material properties had changed as a result of neutron irradiation, but not to the extent expected on the basis of estimated neutron fluences. Yield strength, tensile strength, and dislocation loop density were all lower and ductility much higher than expected. Initially calculated neutron fluence of the material varied between 1x1021 and 2.6x1021 n/cm2, E > 1 MeV (1.5 and 4 dpa, respectively). The newest calculations using Monte Carlo simulations indicate that the real fluences are clearly lower, 0.5x1021 and 1x1021 n/cm2, E > 1 MeV (0.7 and 1.5 dpa, respectively) and below the assumed threshold for IASCC in PWR environment. (orig.)