Rapid Downselection of Potential Fusion Structural Materials Using In Situ Ion Irradiation Transient Grating Spectroscopy

Void swelling and changes in thermal conductivity are life-limiting features of many nuclear reactor components. However, monitoring thermomechanical property evolution of materials in radiation environments has historically been a time consuming and expensive process. Transient grating spectroscopy (TGS) can break this bottleneck because of its ability to directly calculate thermal diffusivity and surface acoustic wave (SAW) speed from ion implanted regions in situ. In addition, results from the in situ ion irradiation TGS system at Sandia’s Ion Beam Laboratory (IBL) have found a relationship between the onset of void swelling and a downturn in the SAW speed. We show that this method can be applied to a range of potential nuclear materials under the same irradiation and temperature conditions in order to rapidly draw conclusions about relative radiation tolerance by minimizing variation in thermoelastic properties as a surrogate for variation in mechanical properties. This is demonstrated using temperature and irradiation damage conditions expected in the ARC fusion reactor being developed at MIT.