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Dry Cask Storage

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11 pointsfreeqaz21 comments

It's a shame we don't do fuel reprocessing in the US. Generally those rods have quite a bit of usable fissile material left it's just fallen below the economic threshold where it's better to replace them than continue using them.

There’s a lot of misunderstandings around repressing and how useful it is. Basically what we’re doing actually makes a lot of sense even if it might not seem that way.

What matters for current reactors is u-235 which is largely consumed by nuclear reactors where the vast majority of extractable uranium in spent fuel is u-238 already considered a waste product “depleted uranium” cheap enough to use for ammunition.

There’s value in extracting a short lived products from a small percentage of spent fuel for use in medicine etc, but in general if you want to do repressing waiting 100+ years makes everything cheaper. As such even if we eventually do reprocessing using dry cask storage until natural uranium runs low is a useful approach.

I think what most people don't realize is that fission is not a nice chemical reaction with defined inputs and outputs.

Fission creates an entire spectrum of elements with different radioactive profiles and nastiness.

To handle it and separate out the useful stuff is incredibly complex and expensive. Reprocessing has never been worth simply because of this.

https://en.wikipedia.org/wiki/Nuclear_fission#/media/File:Th...

> It's a shame we don't do fuel reprocessing in the US.

Not economical currently: uranium is too cheap (even with the extra enrichment that BWR/PWR reactors need).

It'd have to be run at a loss/subsidized. (Which wouldn't necessarily be a bad idea: run (a few?) small scale plant(s) just to maintain a knowledge base in case it was suddenly needed.)

Reprocessing fuel has several benefits. The first is sorting and reducing the volume of waste. Dry casks are an easy solution: the entire fuel assembly is buried.

It is possible to separate the fuel pellets from the zircalloy tubes to reduce storage volumes.

The next step is the reprocessing of spent fuel to separate depleted uranium, plutonium and minor actinides. It is generally this solution that poses a few problems, as plutonium separation techniques can be misused for nuclear proliferation.

The plutonium extracted from spent fuel assemblies is not of sufficient quality for military use. It can be reused in MOX fuel. But not all pressurised water power plants are compatible.

At present, civil reprocessing fuel capacities are insufficient. The La Hague plant has its pools full and is sending some of the fuel to Seversk in Russia. But this agreement came to an end with the war in Ukraine.

Reprocessing is still an option in the future. But it generates a lot of waste streams and as you indicate is more expensive than just fabricating a new rod. Plus our nuclear fleet is in decline and we could see a wave of decommissioned plants in the next decade (if we don't pivot our national energy policy) so our usage of fuel will decline in turn.

I think reprocessing is actually cheaper than creating a new rod because you don't have to do as much enrichment of the uranium material. What I meant is the rod produces less power than a fresh replacement so it's better for the operator to replace it with a new rod to keep the reactor at it's design output.

The main reason the US is against it is because of old Cold War concerns about countries using it to harvest plutonium which is created in small amounts in regular reactors so there's a small concern that reprocessing would allow secretive creation of plutonium for nuclear weapons while appearing to be a purely peaceful civilian nuclear fuel reprocessing system.

>I think reprocessing is actually cheaper than creating a new rod because you don't have to do as much enrichment of the uranium material. What I meant is the rod produces less power than a fresh replacement so it's better for the operator to replace it with a new rod to keep the reactor at it's design output.

At best, reprocessing produces MOX fuel at a similar price to fuel from natural uranium. It is only when the cost of waste treatment is reduced that it becomes economically viable. Uranium from a fuel assembly is completely depleted, containing almost no fissile isotopes. The neutron poisons have to be removed and it has to be mixed with uranium and plutonium oxides so that it reaches a sufficient level of enrichment to be used in a pressurised water reactor. They produce as much power as a new assembly. It's quite difficult to run a reactor at anything other than 100% nominal power.

> The main reason the US is against it is because of old Cold War concerns about countries using it to harvest plutonium which is created in small amounts in regular reactors so there's a small concern that reprocessing would allow secretive creation of plutonium for nuclear weapons while appearing to be a purely peaceful civilian nuclear fuel reprocessing system.

Plutonium from a pressurised water reactor is too impure for military use. It is polluted with actinides, which are neutron poisons. It is the techniques for separating plutonium and actinides that are problematic.

It was possible to use civilian reactors to produce weapons-grade plutonium with graphite-gas reactors. It was possible to load and unload fuel during operation. This allowed the fuel to be ‘cooked’ just to the right point to produce plutonium and little other element. These reactors are obsolete (intense gaze in the direction of the UK).

> Plutonium from a pressurised water reactor is too impure for military use. It is polluted with actinides, which are neutron poisons. It is the techniques for separating plutonium and actinides that are problematic.

That's just what I was able to find as part of the reasoning behind the anti-reprocessing stance the US started back then and continues to follow today. Even a dirty source of plutonium would be a risk for diversion into a more secretive refining program.

Not really. Countries able to reprocess spent fuel generally have a large stock of weapons-grade plutonium from disarmament and warhead upgrades.

For a non-nuclear-weapon nation, there are simpler and cheaper ways of producing higher-quality plutonium than building a fleet of PWR power stations and a reprocessing plant.

The real problem with reprocessing is that it is not very profitable if the cost of disposing of the waste is low.

> I think reprocessing is actually cheaper than creating a new rod because you don't have to do as much enrichment of the uranium material.

It's not cheaper, at least not with current uranium prices:

* https://fred.stlouisfed.org/series/PURANUSDM

* https://tradingeconomics.com/commodity/uranium

* https://world-nuclear.org/information-library/nuclear-fuel-c...

Prices would need to about double before break-even AFAICT:

> Under the range of fuel cycle unit costs evaluated in this report, unit costs for uranium ore concentrates and PUREX reprocessing have the greatest impact on the overall fuel cycle costs for both fuel cycles. Assuming that other fuel cycle cost components are at the nominal values, the fuel cycle costs for a once-through fuel cycle will be lower than those for a plutonium recycle when the unit costs of uranium are $312/kgU ($120/lb U3O8) or lower, and PUREX reprocessing costs are $750/kgHM (kilogram heavy metal) or higher.

* https://www.epri.com/research/products/1018575

For another perspective, the French do it and claim it is economical enough:

* https://www.orano.group/en/unpacking-nuclear/recycled-uraniu...

Isn't the problem that we are usimg rods at all? I thought if we spent a bit of time figuring out the last tiny bit to commercialize molten salt reactors you basically get perpetual reprocessing for free as a byproduct of the reactor design (it should lilely ne equally as safe or safer for dramatically less cost i would think as well)

https://www.funraniumlabs.com/2024/04/choose-your-own-radiat... Is a nice overview of the various other fuel disposal solutions. Worth reading for the section on reprocessing alone. How big of a superfund site do we want to create?

What are the drawbacks of dumping [denser than water] radioactive waste at the bottom of the ocean? Is transportation to a deep-water site too expensive and risky.

I'd bet some combination of ocean and environmental laws & treaties, and zealous Greenpeace types.

Density isn't important - just package it in corrosion-proof heavy containers before tossing over the side. And do that somewhere like the Aleutian Trench - close enough to US territory to easily monitor the area, but remote / deep / inhospitable enough to make it extremely difficult for anyone to pinpoint the waste. Let alone disturb it.

There is a maintenance-free fusion generator in the sky so powerful that it can burn out your retinas from 150,000,000km away.

It is also unmaintainable and expected to run out of fuel in the future. (very distant future)

I wonder how the stats stack up between damage from all the worlds nuclear accidents, and damage from the sun ($ spent to restore degradation of materials from UV, skin cancer, etc.) Bit moot since the sun can't be switched off.

UV is definitely higher -- there are about 300K new skin cancer cases per year world wide and about 60K deaths per year from it. Most (although not all) of these are due to UV exposure. That being said, before you blame the sun itself, a lot of this is due to ozone depletion (which is still a thing even though sometimes people make it sound like the problem is solved just because the ozone hole is shrinking)

https://www.wcrf.org/cancer-trends/skin-cancer-statistics/ https://en.wikipedia.org/wiki/Ozone_depletion

Don't forget to account for the approximately 100% of the global food supply which needs sunlight to grow.

Sure; however, the energy density is too low and 1GW power plant takes much more space than a compact nuclear power plant. Solar panels also degrade and need replacement.

But yes, sure, we need solar too.

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