Advanced Surveillance: Assessing Radiation–Induced Effects in RPV Materials

Dr. Inge Uytdenhouwen

Abstract:

To monitor the degradation of nuclear reactor pressure vessel materialsinduced by neutron irradiation; dedicated surveillance programs are in place. Goal of these programs is to evaluate the effect of neutron irradiation on the mechanical properties ahead of time compared to the real degradation of the reactor pressure vessel. Here the so called Charpy impact test plays a key role. The absorbed energy of a dynamically broken V-notched bar is measured as a function of the test temperature. By comparing the baseline (as-received) behavior with results from the same material exposed to a certain neutron irradiation fluence, a radiation induced change in shape as well as a shift of the transition curve can be observed. The amount of these changes allows then to assess the accumulated irradiation damage of the pressure vessel. Over the past decades large efforts were put into increasing the information that can be gained from such an engineering type of Charpy tests by taking advantage of instrumented tups thatrecord a load change versus time. Analysis of such load – time traces allows to determine a number of additional material properties. In particular flow properties, microcleavage fracture stress, crack arrest performance, ductile crack propagation and characteristic transition temperatures which are more physics based than the conventionally used absorbed energy and lateral expansion levels. In this talk a detailed analysis of information that can be deduced from instrumented Charpy impact testing will be provided, as well as an overview of enhanced surveillance strategies for nuclear reactor pressure vessels.

Bio:

Dr. Inge Uytdenhouwen received her PhD at the University of Ghent, Belgium. After working for more than a decade on materials for Fusion at the Belgian Nuclear Research center (SCK CEN) she accepted recently a new challenge by accepting the role of program manager for reactor pressure vessel materials. In her role she is responsible for commercial, research and irradiation projects around surveillance and safety assessments of generation 2 and 3(+) nuclear reactors.