Stress, strain, neutron transport and radiation effects in a full fusion tokamak device: A virtual MAST-U study

Abstract

A finite-element method (FEM) model for the Mega-Ampere Spherical Tokamak - Upgrade (MAST-U) fusion tokamak has been developed to evaluate stress and deformations in the full device structure and to assess the stability of the whole tokamak with respect to its simulated exposure to an artificial level of neutron irradiation. Here, we use MAST-U as a proxy for a fusion power plant to explore the level of fidelity made possible by modern supercomputing systems. Gravity and atmospheric pressure were used to test the high-resolution FEM model, involving in excess of 122 million elements. Taking the MASTU fusion plasma as a neutron source, we perform full-scale neutron transport calculations to quantify spatial variations in the neutron flux and assess the neutron radiation exposure across the structure. This is a first step towards applying recently developed multiscale computational tools to evaluate the spectrum of stress in the tokamak, identifying the location of stress concentrations as well as their magnitude. This study provides an example of full fusion device neutronics and FEM simulations which are enabling UKAEA to define computational requirements for modelling a whole fusion power plant as well as for specifying operating conditions for the relevant materials.