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Comment by bell-cot | Hacker News Reader

For anything remotely resembling a practical reactor, the cooling system for the reactor vessel would have a boatload of heat to get rid of. So maybe the very hot coolant from there gets pumped through a steam generator, which then feeds a steam turbine, which drives a generator.

Or, you might leave a (carefully-shaped) hole in one side of your reactor, and call it a nuclear rocket.

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There are two ways to do a nuclear rocket. The "clean" way, closed loop. And the "dirty" way. Open loop.

Closed loop is actually not all that different from using a reactor as a generator. But instead of using your cooling system to power a turbine via a head exchanger, you use it to heat a reaction mass such as H2.

Open loop is closer to what you describe. Instead of indirectly heating your reaction mass, you run it directly through the hot reactor. It's simpler and lighter but your exhaust is extremely radioactive. Your reaction mass essentially doubles as the cooling system. Another downside to this approach is you cant run the reactor without making thrust. So lights out if you are coasting I guess.

I like the rocket idea.

There are overwhelmingly better fusion rocket ideas that take no detour through hot neutrons and heat.

Good old nuclear salt water rockets: https://www.npl.washington.edu/av/altvw56.html

Just don't point the exhaust at anything inhabited.

This was my "holy shit" read of the day.

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