Macroscopic elastic stress and strain produced by irradiation

TL;DR

This paper develops a method to compute the macroscopic elastic stress and strain caused by irradiation-induced defects in materials, highlighting the effects of spatial variation in neutron exposure in fusion power plant components.

Contribution

It introduces a novel analytical and numerical approach to quantify irradiation-induced elastic stresses considering spatial defect distributions in fusion materials.

Findings

Spatial variation of neutron exposure causes heterogeneous stress fields.

Elastic stress vanishes on average under traction-free conditions.

Significant stresses are found in irradiated thin films and cylindrical components.

Abstract

Using the notion of eigenstrain produced by the defects formed in a material exposed to high energy neutron irradiation, we develop a method for computing macroscopic elastic stress and strain arising in components of a fusion power plant during operation. In a microstructurally isotropic material, the primary cause of macroscopic elastic stress and strain fields is the spatial variation of neutron exposure. We show that under traction-free boundary conditions, the volume-average elastic stress always vanishes, signifying the formation of a spatially heterogeneous stress state, combining compressive and tensile elastic deformations at different locations in the same component, and resulting solely from the spatial variation of radiation exposure. Several case studies pertinent to the design of a fusion power plant are analysed analytically and numerically, showing that a spatially varying distribution of defects produces significant elastic stresses in ion-irradiated thin films, pressurised cylindrical tubes and breeding blanket modules.