The work performed (WP2) confirms that the investigated neutron flux effects has a negligible impact on RPV and internal steels, in terms of yield stress evolution. The influence of specimen size, specimen cutting location, orientation and irradiation embrittlement on the fracture toughness scattering, the distribution of the fracture (cleavage) initiation size and the reference temperature T0 has been investigated (WP3). The effect of additional uncertainties in RPV surveillance data have been examined, with a view to quantify their impact on the total uncertainty (and scatter) and to improve the use of surveillance data, from an end-user point of view. WP4 has delivered significant, original (rare…), high quality results, in an attempt to develop and underpin fracture models required for management of civil PWR baffle bolt cracking, including advanced characterisation on a post-stress corrosion cracking test specimens, IASCC testing on proton-irradiated material and machined/cold-worked material, including post-test characterisation, TEM investigations on specimens exposed to varying chemical environments, crack initiation tests on neutron-irradiated O-ring test along with visual inspection of the specimens post-test, studies on He effect on grain boundary crack initiation and Cr diffusion experiments within representative PWR temperature range.
Efforts on the modelling of irradiation microstructure were upheld (WP5); including improved description of interaction between point defects, solute, dislocation and grain boundaries, improved description of sink strengths and account of precipitates in rate theory. These developments allow for successful description microstructure formation dynamics, in a set of realistic materials (both RPV and internals) through OKMC-based or rate theory modelling. The results have improved the level of understanding of microstructure evolution and important physical properties (mechanical, chemical, etc…) on radiation hardening and IASCC: in particular, interaction and diffusion of point defects and grain boundaries, depending on the grain boundary types considered. Modelling of oxide kinetics for austenitic model alloy focused on the role of cold working on Cr depletion and highlighted necessary further developments. The developed models has been assessed by the SOTERIA End-User Group throughout the project duration, taking into account industrial reference cases. Recommendations included (1) the delivery of different versions of the platform to the End-User Group, (2) the training of the end users on the particular version, (3) the feedback from the end-users and the consideration of this feedback in the further development of the models.
