Fracture mechanics testing of irradiated RPV steels by means of sub-sized specimens: Summary of ongoing international activities

The FRACTESUS project aims to validate the usage of small-scale fracture toughness specimen testing for the safety assessment of reactor pressure vessels. The work undertaken in the project is aimed to convince appropriate authorities to use toughness data acquired from miniaturized compact tension specimens (MC(T)) in the Master Curve approach and finally introduce MC(T) specimens into surveillance programs.
To achieve this, the effect of specimen size on the fracture toughness properties needs to be studied. Finite element modelling (FEM) is used to investigate the difference between large-size and miniaturized compact tension specimens and to quantify the resulting loss of constraint due to the size reduction. As such, the optimal range of usability of MC(T) specimens can be determined and evidenced with experimental results. Large inter-laboratory testing is included in the FRACTESUS project to prove the repeatability and reproducibility of the small-scale testing of fracture toughness properties.
Fracture toughness on various materials (both base and welds) relevant for most of the available reactor materials and irradiation conditions are investigated. Because of this project, guidelines and standard practices will be composed for the use of MC(T) specimens in the Master Curve approach.
Part of the success of the present project relies on interactions with ongoing international activities: national and international activities related to long term operation of nuclear power plants; standardization bodies; academic and industrial professionals. The present deliverable summarizes the main interactions of the FRACTESUS project with international activities.