Nuclear thermal propulsion takes hydrogen and introduces it to enriched uranium that then heats up the gas and expels it to create thrust. Could you use also use the uranium to heat up water instead and run a turbine for electricity? (Or use some other method to create electricity.)
2$\begingroup$ Minor nit pick, but "reactor" does not mean "generates electricity." A reactor is a vessel in which a controlled nuclear or chemical reaction is allowed to take place for some useful purpose. A "thermal nuclear propulsion" engine that "heats up gas...to create thrust" is a reactor. $\endgroup$– Solomon SlowApr 16, 2020 at 15:31
Yes, it can.
There's also a proposed hybrid nuclear-electric system, described here, where hydrogen is run through the reactor and heated to drive a turbine to produce electricity, then run through a second time to be heated for exhaust as in the basic nuclear-thermal rocket, then further boosted with an electromagnetic accelerator stage.
$\begingroup$ See also: space.stackexchange.com/questions/46314/… $\endgroup$– ikraseJun 30, 2022 at 4:00
To generate power from a turbine, you need a temperature gradient. Using a nuclear reactor as a heat source is straightforward enough, but you would then need to reject that heat after it has passed through the steam turbine. Terrestrial nuclear power stations have enormous evaporative cooling towers for this purpose.
For long-duration space missions, you'll want to conserve mass or your power generation system will run out of coolant. Since heat conduction and convection are not options in space, a radiator is probably your best option for accomplishing this task.
One system you could use for reference is the EATCS (External Active Thermal Control System) on the ISS. It comprises a pair of radiators and two independent heat collection, transportation, and rejection loops that use mechanically pumped ammonia as the working fluid. It can reject 70kW of heat.