We usually think of fissionable materials as releasing particles or nuclei, like alpha particles, electrons, or neutrons, which bounce around in material slowing down
However some isotopes get left with nucleons in an excited state, and when they 'relax' they emit x-ray photons
There are only a few dozen radiation hot cells in the US that are licensed to handle highly active materials
You need meter-thick lead-glass windows, remote handling robotics, concrete, tons of steel
INL's Sample Prep Laboratory was the first one in 50 years, in 2025

