MD simulation of hydrogen embrittlement in tungsten

SCK•CEN Mentor

Bonny Giovanni, gbonny@sckcen.be, +32 (0)14 33 31 98

Expert group

Structural Materials Modelling and Microstructure

SCK•CEN Co-mentor

Terentyev Dmitry, dterenty@sckcen.be, +32 (0)14 33 31 97

Introduction

Tungten (W) was chosen to be the divertor armor material in International Thermonuclear Experimental Reactor (ITER) and is planned to be used as a first wall material DEMO reactor concept. In a fusion reactor the plasma facing materials are bombarded with plasma components such as deuterium (D), Tritium (T) and Helium (He). The biggest safety issue comes from the fact that T is radioactive and toxic. Thus the safety limit of 700 g of T that can be accumulated in the reactor’s chamber was set for ITER. Understanding of the physical mechanisms governing the retention of T in the material is essential for safe operation of the fusion device.

The permeation, accumulation and retention of T in W are defined by the plasma exposure conditions and the microstructure of the material. Moreover, synergetic effects between He and T atoms in the material can play an important role in T retention. Molecular Dynamics (MD) simulations provide an opportunity to study the mechanisms of T retention on atomistic level at finite temperatures.

Objective

Recently developed interatomic potential for W-H-He system allows one to simulate simultaneous accumulation of H and He in the material. The objective of this internship is to perform a number of such simulations in the bulk W and in polycrystalline W. This will allow to assess the influence of the microstructure of the material on the defect formation and subsequent H retention during simultaneous accumulation of H and He in the material. The defect formation detection algorithm will be first benchmarked in a perfect bulk material and then applied to a polycrystalline material. The results will serve for better understanding of H retention mechanisms on atomistic level and provide parameterizations for upper scale models.

The minimum diploma level of the candidate needs to be

Master of sciences

The candidate needs to have a background in

Physics