What is a fusion pile?

[gimmethegepgun]

And why does it need fissiles to function?

[gimmethegepgun]

Originally posted by Plasmon:

Originally posted by ExavierMacbeth:

Couple of options...

3) Could be a replaceable component thats based on a fissible byproduct. Like using depleted uranium for other applications. Some of those materials might have some specific properties that make the fusion pile more effective from a design standpoint, but like everything else have to be replaced as maintanence.

You can burn depleted uranium in breeder reactors, but I don't think it could be used in fusion reactors.

D-T fusion reactors create huge amounts of neutron flux, and generally quite high energy neutrons as well, which can be used in a hybrid fusion-fission reactor to fission more stubborn heavy element isotopes like U-238, much like a fast breeder reactor will. Still, this is not a requirement to have a fusion reactor.

[corisai]

Originally posted by ExavierMacbeth:

The last thing you want is a microsecond spike in your magnetic field to let a lance of super heated plasma free... well unless you want to suddenly learn why plasma weapons are dangerous :P

Actually damage would be surprisingly low.

Sudden surge in magnetic field turning reaction into uncontrollable blast would be muuuuch worse :)

Originally posted by gimmethegepgun:

D-T fusion reactors create huge amounts of neutron flux, and generally quite high energy neutrons as well, which can be used in a hybrid fusion-fission reactor to fission more stubborn heavy element isotopes like U-238, much like a fast breeder reactor will.

Fusion provide neutrons with different energies. So let's say - it could have some use :)

[ulzgoroth]

My guess? It's assumed to be using D-T fission or similar and to breed the tritium using fissiles.

Similar to why the Triton Pulse engine takes fissiles as part of its fuel.

[Corusca Fire]

Originally posted by ulzgoroth:

My guess? It's assumed to be using D-T fission or similar and to breed the tritium using fissiles.

Similar to why the Triton Pulse engine takes fissiles as part of its fuel.

I think this is the best explanation for why it needs a constant supply of fissiles. There is also no reason to ever move away from it for power generation - the other fusion reactions are harder and require more input energy, but you want to move towards those for drives because the neutron flux is not useful for propulsion. The neutron flux is fine for power generation however.

[gimmethegepgun]

Originally posted by ulzgoroth:

My guess? It's assumed to be using D-T fission or similar and to breed the tritium using fissiles.

Similar to why the Triton Pulse engine takes fissiles as part of its fuel.

Except you don't need fissiles to breed Tritium, and they aren't very good at it either, unlike Lithium. Both Lithium-6 and -7 can create it, though -7 is harder and is endothermic.

[ulzgoroth]

Originally posted by Corusca Fire:

Originally posted by ulzgoroth:

My guess? It's assumed to be using D-T fission or similar and to breed the tritium using fissiles.

Similar to why the Triton Pulse engine takes fissiles as part of its fuel.

I think this is the best explanation for why it needs a constant supply of fissiles. There is also no reason to ever move away from it for power generation - the other fusion reactions are harder and require more input energy, but you want to move towards those for drives because the neutron flux is not useful for propulsion. The neutron flux is fine for power generation however.

Neutron flux is kinda obnoxious for fixed-installation power generation.

Originally posted by gimmethegepgun:

Originally posted by ulzgoroth:

My guess? It's assumed to be using D-T fission or similar and to breed the tritium using fissiles.

Similar to why the Triton Pulse engine takes fissiles as part of its fuel.

Except you don't need fissiles to breed Tritium, and they aren't very good at it either, unlike Lithium. Both Lithium-6 and -7 can create it, though -7 is harder and is endothermic.

I have one established case of tritium engine consumes fissiles. I don't have access to other types of tritium engine, so I can't check whether this pattern holds up. It doesn't matter here whether you (or I) think a tritium source should be considered fissiles. We should be able to tell whether the developers do.

But it makes a lot more sense than 'our fusion plants are fission powered'.

[gimmethegepgun]

Originally posted by ulzgoroth:

But it makes a lot more sense than 'our fusion plants are fission powered'.

It doesn't, though. The rate of Tritium production from fission reactions of heavy elements (i.e. not Lithium) is very low, only one in about 10,000 fissions. At best it can be considered a useful byproduct, not an intended purpose.

A hybrid fusion-fission design is by far the most logical explanation I've seen in this thread, but it's still irritating that the requirement for fissiles can't be avoided, seeing as they are not in any way required for a fusion-only reactor.

[ExavierMacbeth]

Originally posted by corisai:

Originally posted by ExavierMacbeth:

The last thing you want is a microsecond spike in your magnetic field to let a lance of super heated plasma free... well unless you want to suddenly learn why plasma weapons are dangerous :P

Actually damage would be surprisingly low.

Sudden surge in magnetic field turning reaction into uncontrollable blast would be muuuuch worse :)

lol, then again it depends on what it hit :P
We know from reality that it doesn't take much to make high energy physics based power plants turn into world class nightmares.

Honestly I don't see a real world fusion plant turning into the super explosion that sci-fi often portrays (Battletech/Mechwarrior reactors anyone?). From what I have seen there is only 1 of the several reactor designs we are developing that would have the plasma density for that and from what I can tell those are the extreme compression based ones that generally don't have very big mag bottles anyway. Tokamak & Stellerator style reactors would be damaged by a magnetic field failure but wouldn't take out a city block :P

[gimmethegepgun]

Originally posted by ExavierMacbeth:

Battletech/Mechwarrior

Battletech is not where one goes to find realism lol. It has lasers that miss and they've apparently never heard of the square-cube law.

[Aranador]

Fusion doesnt really work with typical hydrogen you can extract enmass from water, you need heavier isotopes - which requires neutrons, which you can get from decaying fissiles. Fusion fuel has higher energy density than fission fuel, which is why it is great for your space ships, to keep the needed mass down, but making the fusion fuel doesn't need that energy density. You still gotta get those fissiles though.

[K E N N I]

Don't overthink it, this is a science fiction game. Scientists have been working on sustained fusion for 50+ years with very little success, so we don't know how a fusion pile would work.

[gimmethegepgun]

Originally posted by Aranador:

Fusion doesnt really work with typical hydrogen you can extract enmass from water, you need heavier isotopes - which requires neutrons, which you can get from decaying fissiles. Fusion fuel has higher energy density than fission fuel, which is why it is great for your space ships, to keep the needed mass down, but making the fusion fuel doesn't need that energy density. You still gotta get those fissiles though.

Deuterium occurs naturally at about 1 in 6240 in Earth's oceans. It's by far easier to get Deuterium by separating it from water than it is to manufacture it by capturing neutrons with Protium. This ratio will change on different astral bodies, but I doubt it's all that different. For Tritium, the main source of it is to fission Lithium-6 (or, for an inferior method, -7) by bombarding it with neutrons (and, in this game, lithium is explicitly mentioned as being a part of Metals).

But, even if you want to manufacture Deuterium rather than separating it out, the fact remains that D-T fusion has a FAR greater neutron flux than heavy element fission or decay does. Frankly it's actually a really big problem, which is part of why Lithium-6 fission is so useful, since it consumes neutrons but doesn't release any.

[gimmethegepgun]

Originally posted by dzony:

Don't overthink it, this is a science fiction game. Scientists have been working on sustained fusion for 50+ years with very little success, so we don't know how a fusion pile would work.

Part of the reason I made this thread is because afaict no one notable has called a fusion reactor a "pile" and doing so is inane considering you have to create extreme conditions to get fusion to work at all, unlike fission where the first artificial reactor was literally a pile of graphite bricks surrounding a bunch of uranium.

[ExavierMacbeth]

Originally posted by gimmethegepgun:

Originally posted by ExavierMacbeth:

Battletech/Mechwarrior

Battletech is not where one goes to find realism lol. It has lasers that miss and they've apparently never heard of the square-cube law.

lol that was the joke... Most sci-fi that show nuclear meltdowns or fusion explosions are horribly inaccurate. I just picked one I figured people would easily recognize.

Though honestly I give that one a bit of a break on alot of the other mechanics they get wrong simply because the game universe seems to consider computers a non-existent tech (not surprising from when the game was made). I am pretty sure your smartphone has more computer power than the 1 ton targeting computer or the 6 ton C3 Master computer for remote controlling drones :P

[Mistfox]

Originally posted by gimmethegepgun:

Originally posted by ExavierMacbeth:

Battletech/Mechwarrior

Battletech is not where one goes to find realism lol. It has lasers that miss and they've apparently never heard of the square-cube law.

He was being sarcastic.

Originally posted by gimmethegepgun:

Deuterium occurs naturally at about 1 in 6240 in Earth's oceans. It's by far easier to get Deuterium by separating it from water than it is to manufacture it by capturing neutrons with Protium.

And I believe you hit on a very important phrase you might have overlooked. "In Earth's Oceans". Sure, you might be able to make a case where on sites with water you can do that but what about sites that don't? Remember that your "standard design reactor" is supposed to work everywhere, not just in some locations, which means designing for the "lowest common denominator".