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I hear thorium fission plants don't pose as big of a meltdown risk as uranium and plutonium fission plants, waste from thorium fission only takes 60 to 80 years to break down instead of hundreds or thousands of years, they produce less waste, and thorium is easier to acquire than uranium or plutonium. Is this technology worth investing in?
The fission product in a thorium cycle reactor is U233. It has exactly the same waste product issues as a U235 cycle reactor. The thorium isotope used in the cycle is the most common naturally occurring element of thorium so it is abundant. U233 is more radioactive than U235 so handling unburned fuel has additional issues.
Nuclear power generation is derived by using the energy released as the radioactive fuel material undergoes decay to heat water, turning it to steam, which then spins turbines to make the electricity. The spent fuel is still radioactive and needs to be disposed of. (The spent fuel is no longer efficiently turned to "weapons grade" so it has little extra use.)
The conventional reactors use uranium as fuel.
Thorium reactors start with Thorium, which decays to Uranium, which then decays further as it does in the conventional reactor.
The advantages of starting with thorium is that it is 3x more abundant than uranium and has higher energy density than uranium. (It is also more efficiently diverted to weapons grade uranium, if we find it necessary.) Because thorium is more energy dense, we start with less material and have less spent fuel at the end.
Thorium reactors don't eliminate the problems of conventional reactors, they just improve the efficiency & outcome somewhat.
I hear thorium fission plants don't pose as big of a meltdown risk as uranium and plutonium fission plants, waste from thorium fission only takes 60 to 80 years to break down instead of hundreds or thousands of years, they produce less waste, and thorium is easier to acquire than uranium or plutonium. Is this technology worth investing in?
No.
A better technology makes use of thorium salts.
Even better is a new reactor design that uses reactor waste that already exists. It's still about 10 years away, but even that isn't worth investing. If you built enough reactors to power the US solely on nuclear power using those reactors, it would take 4 centuries to burn up all of the nuclear waste the US currently has stored, and that is not at current electric energy consumption levels, but at anticipated future electric energy consumption levels.
IFRs (Integral Fast Reactors) are worth investing. Unfortunately, the environmentally-challenged duo of Clinton/Gore cancelled all government spending on research.
Fusion reactors, commonly known as "breeder" reactors don't produce any waste, because the "waste" they produce is actually fuel for other fusion reactors.
You need only produce enough fuel to start one fusion reactor, and that's it. The fusion reactor will produce its own fuel, plus enough to start and partially operate another, so if you get two or three fusion reactors going, they'll run forever producing their own fuel, without an ounce of waste.
The danger is the risk of nuclear proliferation, because you can extract Plutonium-239.
That's where the IFR comes in. It's design greatly diminishes the risk of nuclear proliferation.
Every country could run one or more IFRs and you wouldn't have to fear a country operating a clandestine nuclear weapons program.
Fusion/breeder reactors are a far better option than solar or wind, or fission nuclear reactors.
Nuclear power generation is derived by using the energy released as the radioactive fuel material undergoes decay to heat water, turning it to steam, which then spins turbines to make the electricity. The spent fuel is still radioactive and needs to be disposed of. (The spent fuel is no longer efficiently turned to "weapons grade" so it has little extra use.)
The conventional reactors use uranium as fuel.
Thorium reactors start with Thorium, which decays to Uranium, which then decays further as it does in the conventional reactor.
The advantages of starting with thorium is that it is 3x more abundant than uranium and has higher energy density than uranium. (It is also more efficiently diverted to weapons grade uranium, if we find it necessary.) Because thorium is more energy dense, we start with less material and have less spent fuel at the end.
Thorium reactors don't eliminate the problems of conventional reactors, they just improve the efficiency & outcome somewhat.
Energy in U235 or U233 reactors comes from fission not decay.
Whether the spent fuel is a potential proliferation risk depends upon the fuel load and physics of the process. Some spent fuel has enough PU239 to be of concern.
I don't know where you get this density argument, but it's nonsense. What matters is the enrichment of the fission target,
When the US Navy build an operating thorium core, it produced slightly less power than the previous enriched uranium core.
We aren't running short of uranium so there's little pressure to embrace a thorium cycle reactor.
No private sector firm in the United States is likely to take the risk of building another commercial reactor any time soon so the question about fuel cycle is really moot..
You can't run a reactor on just thorium. You have to start with uranium, natural or enriched depending on your choice of moderator, or possibly plutonium.
Thorium 232 transmutes (under neutron irradiation) into U-233, which is a reactor fuel.
The old Fort St. Vrain high-temperature gas reactor worked on a U-235-U233 thorium cycle. When it ran, that is.
There is no specific safety advantage to using a thorium-U233 cycle. The safety advantage is in using a molten salt reactor that is not pressurized, or a high-temperature gas cooled reactor that can withstand very high temperatures (core is ceramic, so it won't melt until very high temperatures). But while I don't know of anyone using thorium in a conventional PWR or BWR, if you did, the basic safety case for the plant would not change (much).
All this recent talk about thorium is interesting, of course, but in fact there are few really new ideas out there for advanced reactors. Thorium-U-233 cycles do have some nonproliferation advantages in terms of the U-232 minor component giving rise to daughters that create a good bit of beta-gamma (and particularly the hard gamma from thallium 208) https://en.wikipedia.org/wiki/Uraniu...U-232_impurity as noted also complicates reprocessing and recovered fuel fabrication.
Breeders always have a seed and a blanket in my experience.
That's true. There are probably some oddball designs that don't, but I can't point to one off the top of my head.
The seed and blanket design makes sense as you have the seed, powered by U-5, U-3, or Pu-9, fissioning, making power and neutrons, part of the neutrons go out into the blanket, where they convert thorium to U-3, or U-8 to Pu-9. Almost like a smokehouse.
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