sigh
First of all, no they don't. Not easily, at least. All existing reactors will breed minute amounts of Pu-238, 239 (weapons grade), 240, 241, and 242. They are negligible in quantity and impossible to chemically separate from the fuel without massive centrifuge facilities. Operating nuclear reactors are also thermal neutron reactors, not fast neutron breeder or even thermal neutron breeder reactors. They are not useful for breeding enriched material in any meaningful sense.
The oft-touted Thorium fuel cycle will in fact breed weapons-grade material as well. Uranium-233 is Fissile and Enriched, which is what you breed when you use Thorium-232 as a fuel source. All Thorium reactors
have to be breeder reactors, because Thorium is not a viable fuel source until you breed it into a fissile Uranium. This breeding will still go up the chain and will result in the production of Plutonium isotopes as well. So yes, you can use Thorium to breed weapons grade material, mostly in the form of U-233.
In order to stop this, most Thorium reactor designs try to make chemical separation of these isotopes impossible by keeping the fission (Caesium-137, etc.) products trapped in the fuel salt. That way if you try to extract enriched material from the reactor, you kill yourself with gamma radiation. And now you see why it's so
ing hard to make a working Molten Salt reactor, because you have all these different isotopes with different chemical properties in your fuel salt and it's easy for several types to sublimate out and form blockages or create compounds that corrode containment.
No it's not and no they don't. Nuclear's high capital costs are because for the past 50 years a mix of fossil fuel interference and anti-nuclear activism (mostly funded by the fossil fuel industry) has set up the industry in the west to fail. Nuclear is not cheap to operate, the average nuclear plant employs more than 560 people when it should employ between 70 and 110 because for decades external interests have intentionally imposed an unnecessary regulatory burden in order to make it economically unviable. It is incredibly difficult for nuclear energy to compete when it's stuck using materials, parts, labor processes, manufacturing processes, construction process, etc. designed in the 1950's and 1960's. You can't use robotic arms to reduce the labor costs of nuclear energy because it takes
years to get that kind of technology certified for use on reactor-grade components. And the certification for reactor grade components is insane. Parts used for the exact same purpose for the exact same specifications and tolerances in non-nuclear facilities have to be explicitly certified for nuclear use which drives up costs.
And this has another impact in that it causes delays, which brings in biased financing models. Our financing of power facilities doesn't value generation out beyond about a 30 year lifespan due to a method of calculating risk in investment of these projects known as discounting. As a result, 5/8 of nuclear's generation is assigned zero value since nuclear plants have 80 year lifespans. Now throw in above-average interest rates and other factors on the WACC of plant construction and suddenly a $4 Billion Reactor actually costs $7 Billion. Now throw in delays. Over, and over, and over, again due to regulatory interference or sheer incompetence in project management and construction. Now it takes a year longer, now it costs 700 million dollars more due to that 10.25% interest rate. Then another delay, and another. Now your reactors cost $14.1 Billion each, the original projected cost of the two-unit plant. (Talking about the two new units at the Vogtle plant specifically there).
The only way to fix this is to limit the discount rate at 5% instead of 10% and the either limit or subsidize the interest rate down to 2-3%. Either way, this only fixes financing bias, it does not fix sheer incompetence in project management that has been exhibited by western contractors.
If you want to do the math, the 1140 Megawatt Allen Steam Station ~7 miles from me generates approximately 310,000 metric tonnes of coal ash every year. One of the two 1185 Megawatt reactors from Catawba Nuclear Generating Station ~3 miles from me generates approximately 30 metric tonnes of spent nuclear fuel each year. A difference of about 10,330 to 1.
That being said, the "football field" analogy only applies to
Spent Nuclear Fuel. It doesn't account for the reinforced concrete containment surrounding used fuel bundles. Nuclear plants also generate a significant amount of low-level and medium-level radioactive waste each year, which is compressed and vitrified and stored in drums. Some of this is not radioactive and is only classified as such due to over-regulation. A lot of it is though. Generally speaking, those materials are typically "safe" within about 80 years or less, depending on the type and class of waste. But it's important to note that there are other waste streams. Uranium mining and enrichment also generates waste, but typically less than the mining and refining processes of other heavy or rare earth metals. Seawater extraction and fast neutron breeders would help eliminate much of that.
Ignoring the problems Protactinium causes in the Thorium fuel cycle and the fuel salt which is why we have yet to actually build a viable Thorium molten salt reactor reactor, no it doesn't. The Thorium fuel cycle has
nothing to do with eliminating the radiotoxicity of the "waste" for the same reason Thorium is not special at all:
it's just a fertile material with a viable fission fuel cycle. That's it.
It instead has everything to do with the reactor physics, neutron coefficients, de Broigle wavelengths, and other particle physics. We design two types of nuclear reactor:
Thermal neutron and
Fast neutron. In a thermal neutron reactor we optimize the waveforms of the neutrons to achieve a slow and controlled fission cycle with very limited production of new neutrons (it's like 1.2 neutrons per fission). In a fast neutron reactor, we use higher-energy neutrons because different atoms have different neutron capture cross-sections that allow the neutrons to attach and cause a decay event which leads to fission. So we use a much wider spectrum of neutron energies and produce more neutrons per fission. This allows fast neutron reactors to fission the unenriched trans-Uranic isotopes that accumulate in reactors (Neptunium, Plutonium, Americium, etc.) which 1. eliminates some of the intermediate-lifespan waste products with higher radiotoxicities and 2. eliminates most of the proliferation-prone isotopes. The second thing this does is it allows the reactor to achieve a near-complete fuel burnup. 95% of nuclear waste produced from a standard thermal neutron light water reactor (CANDU reactors are slightly different because they use heavy water i.e. Deuterium) is usable Uranium fuel because they only achieve about a 3% to 5% burnup of the fuel. Fast neutron reactors can achieve as high as about 95%. This means that virtually the only thing left over is your fission products, which means the radiotoxicity of your material decays to near-natural levels within about 300 years.
However this is true of all "nuclear waste." It's all radiologically relatively safe within about 300 years because of the short half-lives of the fission products. The reason "24,000 years" or other figures are tossed about is because of the old hot particle theory of Plutonium, which basically believed that ingestion of even nanograms of Plutonium was guaranteed to cause cancer and kill you. 24,000 years is the half-life of Plutonium-239. The worry is that Trans-Uranics will eventually breach the various containment systems of a geological repository, enter groundwater, and poison people. There are two problems with this:
1. Hot Particle theory of Plutonium was conclusively disproven in 1975 when 25 people who had all inhaled atomic plutonium working at Los Alamos National Laboratory were still alive. Statistically, they had a >99.5% chance of being dead from lung cancer by that time. Not a single one of them had developed cancer.
2. It takes about 10,000 years for any particles from spent nuclear fuel (which is a solid, not a liquid, contrary to popular belief) to make it out of a Geological repository and enter the groundwater,
assuming everything goes wrong in the worst possible way. When POSIVA did this study when the Onkalo repository in Finland was proposed (which will be operational in 2022 or 2023), they found the average dose to a human would be 0.2 microsieverts (or the equivalent of eating two bananas, or the equivalent of living next to a nuclear power plant for 2 years). There is absolutely
no evidence of increased cancer rates in doses below 100 millisieverts (so more than 500,000 times higher) and evidence for an increased risk of cancer for doses between 100 mSv and 200 mSv is shoddy at absolute best. And even if the Linear Non-Threshold model is true at doses of 100 to 200 mSv, your risk of cancer assuming continuous ingestion would only go up by 0.35% per year from the baseline 40% in modern Humans. And that's still 500,000 to 1,000,000 times more than what you'd actually be getting from that exposure to Plutonium.
(Also, you still have to reprocess existing spent nuclear fuel into PUREX or MOX fuel before you can use it in a Fast Neutron Breeder, for mostly chemical reasons.)