While studying materials science at the University of Oxford in the United Kingdom, Charles Hirst had an a-ha moment that led him on a path to investigating nuclear materials for both fission and fusion reactors.<\/p>\n\n\n\n
\u201cIn my materials science training, we learned a lot about the aerospace industry and alloys used inside jet engines,\u201d he says. \u201cBut if you put one of these specialized alloys into a nuclear reactor, the neutron radiation would rearrange the atoms inside the material and turn the exquisitely designed microstructure into scrambled eggs. That material couldn\u2019t survive such a demanding radiation environment. And I thought, \u2018Wow, that\u2019s the ultimate challenge,\u2019 which is why I\u2019m a nuclear materials scientist.\u201d<\/p>\n\n\n\n
Hirst<\/a> joined the University of Wisconsin-Madison Department of Nuclear Engineering and Engineering Physics<\/a> as an assistant professor in August 2024.<\/p>\n\n\n\n In his research, Hirst explores the interplay between radiation damage, temperature and stress to determine how materials will behave in harsh irradiation environments. He uses various microscopy and characterization techniques to understand what\u2019s happening inside a material at the atomic level and to investigate how defects in the material evolve as a function of time, temperature and applied load. \u201cOnce we understand the mechanisms behind those processes, we can design better, more resilient materials for the next generation of fission and fusion reactors,\u201d he says. \u201cAnd we can design mitigation strategies for existing materials that are currently in nuclear reactors.\u201d<\/p>\n\n\n\n For example, Hirst says one strategy for extending the lifetime of current reactors could be to heat up the reactor materials. This would rearrange the materials\u2019 atoms, which could \u201cheal\u201d some of the radiation damage and recover the materials\u2019 original properties. Through his research, Hirst could provide reactor operators the details\u2014like what temperature to heat the materials at, and for how long.<\/p>\n\n\n\n Hirst aims to create \u201cmaps\u201d to describe the relationship between temperature and mechanical load to establish safe zones for current and future nuclear materials. \u201cDesigners could use these maps to, for instance, know that they could safely operate a reactor at a higher temperature if they reduce the mechanical load on the material,\u201d he says. \u201cSo, ultimately this materials science knowledge could inform operational practices for reactors.\u201d<\/p>\n\n\n\n