I don't know much about modern reactors but I suspect even 3rd gen ones will still require immense shielding of a cabin and will be single contour design, meani

I don't know much about modern reactors but I suspect even 3rd gen ones will still require immense shielding of a cabin and will be single contour design, meaning that exhaust will be irradiated, maybe less so than on prototypes from cold war. And as I remember soviet Tu-95LAL that did flew with a reactor did so WITHOUT any significant shielding for the crew.