Are these things really radiation-hardened enough to go into a "hot zone"? Won't that seriously mess with any semiconductors? Various manufacturers make radia

Are these things really radiation-hardened enough to go into a "hot zone"? Won't that seriously mess with any semiconductors? Various manufacturers make radiation-hardened microcontrollers and so forth for going into space, but that's nothing compared to a nuclear reactor... or am I wrong? I guess you could encase the motherboard in lead or something.