How well does interstellar model nuclear reactors?

[WhiteWeasel]

How well does the interstellar mod model nuclear reactors? This is a question I probably should ask fractal UK (author of interstellar), but he has been away from the forums for a few weeks now. And I don't think he's coming back soon.

https://github.com/FractalUK/KSPInte.../wiki/Reactors

So far I'm just talking about the standard fission reactor. Compared to real life reactors how realistic is KSPIs nuclear reactor? As well as few questions as to how they work.

-The of use of UF4, ThF4, and U2N3, why do those additional elements make your fuel better than uranium by itself?

-Actinide production and why is bad for your reactor?

-I think can see why you have to turn off your reactor and let it cool down before refueling it.

-The correlation between waste heat and reactor efficiency, the lower the difference in thermal gradient, the poorer the energy transfer? So that means less efficiency the worse your cooling is right?

-Molten salt vs particle bed

-Anything else I missed?

[magnemoe]

At least cooling is important for any heat engine, they work with temperature difference so if you are only able to cool the feed water to 70 degree before returning it you get far less effect out.

An problem in space is water circulation in micro gravity. On earth steam rises to the top of the reactor.

[Ralathon]

How well does the interstellar mod model nuclear reactors? This is a question I probably should ask fractal UK (author of interstellar), but he has been away from the forums for a few weeks now. And I don't think he's coming back soon.

https://github.com/FractalUK/KSPInte.../wiki/Reactors

So far I'm just talking about the standard fission reactor. Compared to real life reactors how realistic is KSPIs nuclear reactor? As well as few questions as to how they work.

-The of use of UF4, ThF4, and U2N3, why do those additional elements make your fuel better than uranium by itself?

UF4 is better than normal uranium metal because you can heat up the salt until it melts and then use that simultaneously as your fission fuel and coolant. Instead of bringing your coolant to your fission fuel you bring the fuel to the coolant. This results is a higher operating temperature and thus better efficiency. These reactors can also be pretty small, so they're more suitable for aerospace applications.

ThF4 is the same idea as UF4, except it uses Thorium as a fuel. This has some benefits and some downsides. Most notably, thorium is much more abundant than Uranium and it can work at slightly higher operating temperatures, but thorium isn't fissile without some serious preparation, much more than Uranium.

U2N3 is again a uranium salt, but I can't find much info on this. I presume it simply runs on a higher temperature. It also doesn't require fluor during its production, which is a horrible horrible substance.

-Actinide production and why is bad for your reactor?

Actinides are created when the Uranium atoms in your fuel are hit with neutrons/protons/alpha particles and transmute into other metals. This is bad for your reaction since these materials aren't fissile. So you need to get rid of them.

-I think can see why you have to turn off your reactor and let it cool down before refueling it.

Handling heavy rods that are horrendously radioactive and a few hundred degrees hot is a bad plan yea.

-The correlation between waste heat and reactor efficiency, the lower the difference in thermal gradient, the poorer the energy transfer? So that means less efficiency the worse your cooling is right?

Yes, simple thermodynamics teaches us that the maximum energy you can ever get from a temperature difference is E_max = E_flow * (1- T_cold/T_hot). Where E_flow is the energy flowing from the hot side to the cold side through your heat engine. The colder your cooler and the hotter your reactor the better its going to get. In KSPI waste heat represents the temperature of your cold side on the heat engine. So lower is better.

-Molten salt vs particle bed

In a particle bed reactor you have your fuel stored in small pebbles that are nigh indestructible. This means it is safe to up the temperature in the reactor to a blistering 1600 celcius. Whereas the average molten salt reactor runs on a measly 700 celcius.

[WhiteWeasel]

In a particle bed reactor you have your fuel stored in small pebbles that are nigh indestructible. This means it is safe to up the temperature in the reactor to a blistering 1600 celcius. Whereas the average molten salt reactor runs on a measly 700 celcius.

I also heard molten salt is better for long duration power while particle bed produces much more energy, but also has much higher fuel consumption.

[architeuthis]

I also heard molten salt is better for long duration power while particle bed produces much more energy, but also has much higher fuel consumption.

For space applications, one advantage of using a molten salt coolant is that you can use it to drive a magneto-hydrodynamic generator directly, instead using a brayton or rankine cycle steam turbine. A MHD generator is less efficient, but as it has no moving parts it is much more mechanically reliable.

[WhiteWeasel]

Hey, do you also have to turn off the reactor for the refinery to reprocess the actinide waste in interstellar?