Fusion neutrons do damage no other source reproduces.
Fusion power plants will expose structural materials to a harsh neutronic environment whose conditions cannot be replicated anywhere on earth. We’re building the world’s only facility capable of validating performance under commercially-relevant conditions.

Since 2020, 3 landmark reports have repeatedly emphasized the need for materials testing before power plants can be brought online. But no such capabilities have been developed.
“Immediately establish the mission need for an FPNS facility … pursue design and construction as soon as possible.”
We can qualify materials with just kilowatts of fusion power.
Performance is a matter of survival under high DPA (displacements per atom), the shifting of each atom in the lattice. Because DPA scales directly with power density, we can generate commercially representative conditions in a compact device.