Ion beam method to speed nuclear core material qualification

by Clarence Oxford
Los Angeles CA (SPX) Mar 30, 2026
An ion beam based method for qualifying materials for use in the cores of advanced nuclear reactors is moving into industry standards this year, offering a path that is about a thousand times faster and far cheaper than conventional test reactor approaches. The methodology is advancing through stages of approval by the standards organization ASTM and will be presented at a special Electric Power Research Institute event in Charlotte, North Carolina, on March 10-11.

Many developers of advanced nuclear fission and proposed fusion systems are looking to new reactor designs to supply emissions free electricity and power energy hungry applications such as artificial intelligence data centers. However, traditional ways of proving that structural materials can survive inside reactor cores have struggled to keep pace with the very high lifetime radiation doses that some advanced designs require.

Under the old approach, test reactors must expose candidate core components to neutron irradiation conditions representative of their design lifetimes. For some advanced reactors, this can mean more than a decade to build up the necessary dose, making every design iteration slow and expensive. By contrast, ion beam irradiation in dedicated laboratories can deliver comparable damage levels in a matter of days and at a fraction of the cost, enabling much faster screening of materials.

Researchers have been investigating whether ion beams can faithfully reproduce the damage that accumulates in reactor environments for more than 35 years. The central question has been whether ion induced damage genuinely mimics the evolution of microstructural changes seen under neutron irradiation. The emerging answer is positive, and the approach has now been formalized as a methodology known as Qualification under Ion irradiation of Core Components, or QUICC.

Key support for the long program of work that underpins QUICC has come from the U.S. Department of Energy, the Electric Power Research Institute, Oak Ridge National Laboratory, Framatome and Rolls Royce. The core technical team brings together specialists from the University of Michigan, Pennsylvania State University, Oak Ridge National Laboratory and the University of Tennessee.

"The QUICC methodology, applied to two very different alloys, demonstrates that the critical changes to the materials under ion irradiation mimic those under reactor irradiation. The significance is that ion irradiation can be used to predict material behavior in reactors 1000 times faster than with test reactors and at one one-thousandth the cost," said Gary Was, University of Michigan professor emeritus of nuclear engineering and radiological sciences, who led the development of QUICC.

Radiation damage is measured using a metric known as displacements per atom, or dpa, which reflects how many times on average each atom in a material is knocked out of its lattice site. The displacement can be caused directly by an incoming neutron or, more often, by a neighboring atom that has itself been displaced. For some advanced reactor concepts, core materials may need to withstand up to around 200 dpa or even higher over their service lifetimes.

At such high damage levels, the crystal lattice of a metal will accumulate many regions where atoms are missing or misplaced, leading to complex defect structures. These microstructural features can embrittle the material and increase its susceptibility to cracking under stress. Radiation can also generate cavities that cause macroscopic swelling, while transmutation gases such as helium can form bubbles that further enhance swelling and degrade mechanical performance.

Neutron irradiation studies require access to specialized test reactors, but ion irradiation can be carried out in ion accelerator facilities located at research laboratories and universities. The QUICC methodology centers on careful control of ion irradiation conditions so that the faster damage rates and limited penetration depth of ions still produce microstructures that emulate test reactor exposure. This control is essential to making ion irradiation a reliable surrogate for reactor testing.

To reproduce conditions in fission reactors, the QUICC approach uses two ion beams. Heavy ions, selected to match the dominant metal species in the material, deliver most of the displacement damage without introducing significant compositional changes. A second helium ion beam is used to implant helium and form gas bubbles within the material, capturing the way helium is produced through nuclear reactions in operating reactors.

The University of Michigan team at the Michigan Ion Beam Laboratory has also developed a target chamber that allows test specimens to be submerged in water at high temperature and under pressure while they are being irradiated. This setup simulates the coolant and thermal conditions experienced by core components in water cooled reactor systems, adding another layer of realism to the ion based qualification process.

For fusion reactor environments, the methodology has been extended to handle the simultaneous presence of helium, hydrogen and displacement damage. In that case, the team uses triple beam irradiation with hydrogen, helium and heavy ions in proportions chosen to match the expected fusion reactor conditions. This triple beam configuration aims to emulate the complex combination of particle species and energies that materials will encounter in a fusion device.

In addition to Was, the QUICC development team includes Kevin Field, University of Michigan associate professor of nuclear engineering and radiological sciences; Brian Wirth and Steven Zinkle, nuclear engineering professors at the University of Tennessee; Arthur Motta, nuclear engineering professor at Pennsylvania State University; and Stephen Taller, staff scientist at Oak Ridge National Laboratory. The group plans further presentations of the method to the materials science community.

Was is also scheduled to present the QUICC methodology at the 2026 TMS meeting in San Diego on March 17, bringing the work to a broader audience of materials researchers and engineers. Materials irradiated at the Michigan Ion Beam Laboratory have been characterized at the Michigan Center for Materials Characterization, which, like the ion beam facility, is supported through indirect cost allocations in federal research grants.

The team is collaborating with U M Innovation Partnerships to develop license agreements that will help transfer the QUICC technology to commercial and industrial users. By embedding the new methodology into standards and licensing frameworks, the researchers aim to make fast, ion beam based qualification broadly available to companies developing advanced nuclear technologies.