Hyperion nuclear batteries are all over news lately... Looks rather fishy to me. According to Britannica, about 15% of heat in nuclear reactor core come from decay of fission products. Unlike fission, decay can not be controlled. For 25MW thermal, that is some 3.75 MW. And for 50MW thermal (which you need to get 25MW electric from turbines), that's 7.5MW Quite non-trivial amount of heat for a hot-tub sized thing, surely enough to melt it down. I'm yet to see any mention of multiple redundant coolant pumps, or anything similar. Just that talk how it can not meltdown, which is pure bullshit.