While much progress has been made to replicate neutron irradiations with ions, this “neutron-ion handshake” between irradiation conditions remains elusive. The slow workflow of all irradiation and post-irradiation examination, scarcity of historical neutron irradiation data, and importantly variable changes when switching from neutrons to ions contribute. The “handshake” will match microstructure and structural material properties between historical irradiations of five key materials, and those which we will perform in this project. Concurrent triple-beam ion irradiation, in addition to in situ characterization, are the two keys to increasing the throughput of information by over 1000× to finally establish this handshake.
The overarching goal of this project is to create the capability for rapid, but vigorously verified, ion irradiation testing of potential ARC structural materials. With no accessible fast neutron irradiation facilities in the world, and a fusion prototypical neutron source years to decades away, we need to create neutron irradiation data for existing, high technology readiness level alloys at high temperatures – data which does not exist, and cannot be extrapolated from those at lower temperatures due to extreme non-linearities in radiation-induced microstructural changes. The picture gets even more complicated when taking into account neutron spectrum which, while displacements per atom accounts for different primary knock-on atom energies, does not take into account different hydrogen and helium production rates from (n,p+) and (n,α) nuclear reactions. These properties, such as void swelling incubation dose, void size/density distribution, and the same for radiation-induced precipitate formation/dissolution, constitute the microstructural match sought when establishing our neutron-ion handshake.
In order to achieve this goal, we will answer a series of research questions, some of which have eluded us for decades, some of which are newly posed. The answers together will establish the scientific footing to create licensable data for fusion reactor components. These include:
1. Which conditions of irradiation temperature and H/He gas co-implantation can recreate the same radiation-induced microstructural/property changes observed in historical fast reactor irradiations?
2. How can domestically available fission reactors best be turbocharged to produce bulk specimen irradiations ready to create design and licensing data?
3. How can this proposed workflow be optimized to quickly vet new materials as they are proposed?
Prof. Gary Was (University of Michigan), Dr. Charles Hirst (University of Michigan), Aaron Penders (University of Michigan), Dr. Cody Dennett (CFS), Dr. Lauren Garrison (CFS)
Commonwealth Fusion Systems
