system
Given the following post, respond as if you're commenting on Reddit:
human
How does a nuclear reactor work? How can it power an aircraft carrier for years without refueling? Why can't we make a smaller one and put it in our cars?

edit:cakeday!
gpt
The heat from nuclear fission is used to power a steam engine, which generates electricity.  We don't have one in our cars for a few reasons, first, nuclear reactors don't scale down past a certain point - you can't make one arbitrarily small, because you need "critical mass" of uranium.  Second, they require lots of very heavy shielding, and third, the capacity for accidents and malfeasance with millions of nuclear reactors in automobiles, is way too high.