Reactors: Fusion vs Fission

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Heero
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Reactors: Fusion vs Fission

Hi

We all know that Ultracompact Fusion Reactors were used in probably all the Gundams shows
and we know that Ultracompact Nuclear Fission Reactors were used in SEED/Destiny series
i see a lot of opinions in everywhere ( youtube ... etc ) that Fusion > Fission and i think it's
true .. but i need to know why , what is the difference between those two reactors and why
is Fusion better .. what is Fusion features that is no seen in Fission
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Kavik Ryx
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Re: Reactors: Fusion vs Fission

In short, fission draws upon energy from the weak nuclear force, while fusion the strong.

The bonds between fermions (protons and neutrons) are indeed more powerful than the bonds between atoms (the electromagnetic force). However, like it takes more internal energy to hold subatomic particles together molecules, metals, and ionic compounds, the internal energy required the hold three quarks (the particles that make protons and neutrons) together is much greater. Fusion draws from this higher energy level.

Fusion works because the strong force in four separated fermions is actually higher than if they were together in a single helium atom. Thus, by forcing the four particles into a larger atom, energy from the strong force is released, which can then be be utilized. The helium atoms may then fuse to form oxygen and carbon, and then iron, though each with significantly less returns.

There is more to it, but much of it comes down to a higher yield, due to the source of the energy.
DougCos
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Re: Reactors: Fusion vs Fission

For a more basic answer, Fission is the tearing apart of atoms while Fusion is the combining (or fusing) of atoms.
In fission, a heavy element (uranium, plutonium) is split apart by firing neutrons into it. This results in lighter elements and energy. The problem with fission is that fissile elements are not stable which means that they release radiation as they decay. The lighter elements that result from fission are also not stable and some are even more radioactive than the base material. Fission is how all nuclear power plants and all nuclear weapons (or at least the first stage) function.
In fusion, two atoms of a light element are fused together to form a heavier atom. This is how the sun and all stars produce light. 2 Hydrogen atoms are combined to get 1 helium atom and energy. This process is "clean" since both hydrogen and helium are not radioactive. It also produces more energy than fission. The problem is that it takes immense pressure to cause the fusion to happen. In stars this comes from the gravitational forces. To replicate on earth it takes a large amount of energy to cause fusion to happen. I think i read somewhere that we have been able to break even, though I can't remember where. That would mean for every Joule of energy we use to cause the fusion we get back one joule. So, for the time being fusion is not useful for energy production. Fusion is used in nuclear weapons as a second stage where the energy of the fission reaction is used to fuse atoms together and release an even bigger explosion.
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Malcadon
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Re: Reactors: Fusion vs Fission

The funny thing about Minovsky fusion reactors (like a lot a fusion reactors in sci-fi) is the lack of waste heat, and the lack of heat radiators to remove it. Naturally, sci-fi writers like to ignore them because they look like big, bulky solar panels, and most people would see them as such. They would rather have the mecha blowup with a clean hit to the engine, then to have them burn-up from the inside-out from the heat radiators being shot off or damaged.

Now, how funny would the One Year War look if all ships and mobile suit/armor had to use heat radiators? The mecha-on-mecha action would be less dramatic in a fight, especially when the pilot has a chance to escape before meltdown. If applied to The Legends of Galactic Heroes, it would really add to that Age-of-Sails-IN-SPACE! motif.
DougCos
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Re: Reactors: Fusion vs Fission

If I remember correctly, Mobile Suits use the waste heat for their propulsion. They heat helium and the expansion of the gas translates into thrust. Also, when Mobile Suits return to their ships they need to use special equipment to cool down the Mobile Suit, so its safe to say that the remaining excess heat just builds up in the machine until it returns to its ship. Obviously, all of that comes from side material, not the shows themselves. As for the ships, we definitely see some with large radiator fins which would be how they deal with the large amount of heat from their reactors.
Mythgarr
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Re: Reactors: Fusion vs Fission

If you read sci-fi novels from the 70s or 80s, you can see that they propose controlled nuclear reactions to drive out reactive mass aka propellants. The reactive mass itself can even be water, forced out by controlled nuclear explosions, giving forward accelerations to whatever is using the reactors.

For Mobile weapons, I believe the compact fission reactors used in ZAFT-made machines supply electricity for the systems. I dunno what the propellant used though, especially Destiny's pink wings...
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