> So plans to shield lunar occupants using the moon's own materials will need to compensate for the ionizing radiation that those materials are already emitting

> So plans to shield lunar occupants using the moon's own materials will need to compensate for the ionizing radiation that those materials are already emitting, separately from cosmic/solar radiation. It's not really that they're emitting them "separately" -- they're radioactive (with mostly short half lives) largely because of solar bombardment. Thin shielding can paradoxically make things worse by converting high energy protons into more, lower energy neutrons. If your shielding is thick, the inner layers will rapidly become less radioactive (the important half lives are less than 30 days). The outer layers will keep getting hit by solar protons and creating more unstable elements. Another major concern in the long term: radon gas. One had better have an inner hull and never rely upon sintered regolith to hold atmosphere.