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Dry Cask Storage

en.wikipedia.org

11–20 of 23 posts

Re: Dry Cask Storage

#11
post #2

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.

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...

Re: Dry Cask Storage

#12
post #2

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.

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.

Re: Dry Cask Storage

#13
post #6

Earlier quoted context omitted.

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…

>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).

Re: Dry Cask Storage

#14
post #10

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.

Re: Dry Cask Storage

#15
post #3

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

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.

Re: Dry Cask Storage

#17
post #2

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.

Re: Dry Cask Storage

#19
post #6

Earlier quoted context omitted.

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…

>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…

> 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.

Re: Dry Cask Storage

#20
post #19

Earlier quoted context omitted.

>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…

> 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 f…

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.

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