Led by the French Alternative Energies and Atomic Energy Commission (CEA), the TCOFF-II initiative aims to enhance expertise and knowledge dissemination in thermodynamics modelling applied to materials science. Its objectives include improving the management of thermodynamic data's impact, including validation, uncertainty propagation, and sensitivity analysis, within severe accident codes. This endeavour will offer training opportunities for current engineers and researchers in data manipulation and the application of thermodynamic calculations specific to accident scenarios. Furthermore, it seeks to facilitate knowledge exchange and raise awareness within the scientific community regarding the dearth of fundamental data concerning severe accidents and their repercussions.

Background

The TCOFF-2 joint project aims to improve the models describing the materials interactions and the role they play in the various phases of the severe accidents, the ultimate goal being the integration of such models in severe accident simulation codes to increase their accuracy.

This improvement will be driven in particular by state-of-the-art knowledge of the thermodynamic properties of the material systems relevant to the description of core materials degrading through a severe accident sequence. Such knowledge, partially developed and accumulated during the execution of the first phase of the TCOFF (TCOFF-1) project and previous international efforts, will be systematised and further extended in this second phase of TCOFF (TCOFF-2) through joint experts’ evaluations, thermodynamic modelling, and focused R&D efforts.

The project focuses on the accident sequence going from the early stages of the fuel degradation, through the fuel relocation, the molten pool formation, reactor pressure vessel (RPV) failure, and the interaction between the corium and the concrete. The project will also address the fission products (FPs) behaviour, their distribution in the various phases forming during the accident and the source term evaluation.

Objectives

The main objectives of the TCOFF-2 NEST project are:

1. to strengthen training and knowledge transfer in the field of thermodynamics modelling applied to materials science.
2. to ensure better control of the impact of thermodynamic information (data validation, propagation of uncertainties, sensitivity analysis) in severe accident codes.

This project will provide training for current engineers and researchers in data handling and the use of thermodynamic calculations dedicated to accidental scenarios. For younger people, it will enable them to take advantage of the current momentum and renewal in the nuclear field to develop the skills of new generations of professionals. More broadly, this transfer of knowledge will also raise awareness throughout the scientific community of the lack of fundamental data in the field of severe accidents and their consequences.