Understanding Fission Gas Bubble Distribution, Lanthanide Transportation, and Thermal Conductivity Degradation in Neutron-irradiated {\alpha}-U Using Machine Learning

TL;DR

This paper employs machine learning to analyze post-irradiation data of U-10Zr nuclear fuel, providing new insights into fission gas bubble distribution, lanthanide transport, and thermal degradation, aiding mechanistic understanding for fuel qualification.

Contribution

It introduces a novel machine learning-based method for automatic detection and classification of fission gas bubbles and links these to lanthanide transport in irradiated nuclear fuel.

Findings

Automated detection and classification of ~19,000 gas bubbles.

Quantitative correlation between gas bubbles and lanthanide transmutation.

Versatile approach applicable to studying irradiation effects like thermal conductivity degradation.

Abstract

UZr based metallic nuclear fuel is the leading candidate for next-generation sodium-cooled fast reactors in the United States. US research reactors have been using and testing this fuel type since the 1960s and accumulated considerable experience and knowledge about the fuel performance. However, most of knowledge remains empirical. The lack of mechanistic understanding of fuel performance is preventing the qualification of UZr fuel for commercial use. This paper proposes a data-driven approach, coupled with advanced post irradiation examination, powered by machine learning algorithms, to facilitate the development of such understandings by providing unpreceded quantified new insights into fission gas bubbles. Specifically, based on the advanced postirradiation examination data collected on a neutron-irradiated U-10Zr annular fuel, we developed a method to automatically detect, classify ~19,000 fission gas bubbles into different categories, and quantitatively link the data to lanthanide transpiration along the radial temperature gradient. The approach is versatile and can be modified to study different coupled irradiation effects, such as secondary phase redistribution and degradation of thermal conductivity, in irradiated nuclear fuel.