Irradiation Induced Dimensional Changes in Bulk Graphite; The theory

TL;DR

This paper introduces a diffuse domain structure model to explain irradiation-induced dimensional changes in bulk graphite, providing a new method for more accurate lifetime estimations of reactor graphite components.

Contribution

It presents a novel concept of diffuse domain structure in reactor graphite and a method to convert experimental shape-change data to bulk properties.

Findings

Domain structure explains size effects in irradiated graphite

Method improves accuracy of lifetime estimations

Estimates of domain size and orientation degree

Abstract

Basing on experimental data on irradiation-induced deformation of graphite we introduced a concept of diffuse domain structure developed in reactor graphite produced by extrusion. Such domains are considered as random continuous deviations of local graphite texture from the global one. We elucidate the origin of domain structure and estimate the size and the degree of orientational ordering of its domains. Using this concept we explain the well known radiation-induced size effect observed in reactor graphite. We also propose a method for converting the experimental data on shape-change of finite-size samples to bulk graphite. This method gives a more accurate evaluation of corresponding data used in estimations of reactor graphite components lifetime under irradiation.