back to article Britain's on the brink of a small-scale nuclear reactor revolution

For the first time ever in April, the UK's data centres and clouds ran on electricity generated without burning coal. The National Grid celebrated the news on Twitter with the promise of more coal-free days to come. As coal-fired power plants wind down and with talk of blackouts in the air, nuclear is back on the table after …

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Re: Underground

"This technology is going to take so long to develop the cash might as well go on fusion research. "

Except that unlike fusion systems, the USA ran a working Molten Salt reactor between 1964 and 1968, the identified problem mainly being corrosion and certain metals plating out at cold spots. Research got killed by Nixon in 1972 for political reasons - primarily being no jobs for the boys in southern california, but compounded by the fact that the MSRs were virtually impossible to weaponise so the military was against it.

https://en.wikipedia.org/wiki/Molten-Salt_Reactor_Experiment

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@Trigonoceps occipitalis: Re: Underground

And limit number four:

Physical: Do not spend more energy in safety devices (and waste removal) than the reactor will generate in its lifetime.

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Anonymous Coward

Re: locomotive tests

"The locomotive tests outmassed and out "grunted" any aircraft you could think of."

Would that be the UK locomotive tests where the engine was mechanically disconnected from the locomotive frame, thereby reducing the impact effects? The locomotive frame hits the fuel container, and is rapidly stopped, but the engine itself then briefly continues to slide along inside the locomotive and its energy is dissipated relatively slowly, reducing the effect on the fuel container.

Conceptually similar to crumple zones in a car - dissipate the energy more slowly rather than all at once.

Now, why might they have done that?

And then there's the small matter of the effects of the fuel carried on board a passenger jet, vs the fuel on a rail locomotive.

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Boffin

Re: Placed underground you say ?

Bury the waste in tectonic plate sub-duction zones, keep the centre of the earth molten!

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Happy

Re: Placed underground you say ?

While they did demo trains hitting nuke waste containers I have never seen a 747 crashed into a power station containment vessel, I would pay to see that

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Anonymous Coward

Re: Placed underground you say ?

>The locomotive tests outmassed and out "grunted" any aircraft you could think of.

Doubtful - the effect of speed is exponential and they weren't carry several kilo tonnes of aviation fuel. I wasn't aware they'd tested a containment wall using a locomotive - sure you're not thinking of waste fuel containers?

When it really matters they hollow out a mountain.

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Weird

Ummm, so much wrong, a Gish Gallop of wrong repeatedly wronged. I congratulate you, I've not seen so much sequential nuclear tech wrong since I accidentally listened to a couple of minutes of Helen Caldicott on a Youtube video.

No-one has built a LFTR ever so saying definitively what they can do is a bit of a stretch. There's a lot of Youtube videos, Powerpoint presentations and grad student TED Talks about them but no actual operational experience. The molten-salt reactor at Oak Ridge National Laboratories failed in many ways and it never ran with thorium (it used uranium). "Thorium" fuelled reactors actually burn uranium, the thorium is bred up into U-233 before being fissioned to produce energy and radioactive waste. Thorium by itself is not fissionable.

Uranium is commonplace, not rare. It's simple to refine. Sources are not limited. It is incredibly cheap to buy on the open world market and a number of large mineable deposits are not being exploited because the market is effectively saturated. Uranium as a metal is not particularly toxic, in part because the common forms are very insoluble and can't enter the bloodstream or digestive system easily. The damage, if it does cause any, is limited to some effects on the renal system. It's not evil poisonous stuff like beryllium or cadmium or arsenic or lead or a dozen other elemental toxins with low LD50 and bad neurochemical effects.

No nation extracts plutonium from civil nuclear reactor fuel[1] -- it's hopelessly contaminated with Pu-240. All of the nations with nuclear weapons made their stocks of nearly-pure Pu-239 is specialised reactors in places like Windscale and Hanford. All of those nations have more weapons-grade Pu than they will ever need, indeed it costs them to securely store the surplus after the number of weapons held was vastly reduced in the 1960s (Britain had over five hundred nukes at one time, today it has about 140 or so). Any power reactor built after the early 1970s had nothing to do with making extra nuclear material for weapons. There were a couple of designs that could be co-opted to make weapons-grade material, the British Magnox and the Russian RMBK-4 but I don't think they ever actually did since there were proper weapons-grade breeder reactors available to both nations.

[1] It's possible North Korea tried reprocessing spent commercial reactor fuel in the early days of its nuclear weapons development. The first few tests did not work out for them, you may recall.

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AGRs, the nuclear Betamax

The Advanced Gas-cooled Reactor (AGR) was an evolutionary upgrade from the semi-militarised Magnox design and had a lot going for it such as efficiency since it runs hotter than a PWR. Unfortunately that benefit would only make it a commercial success if the fuel was rare and expensive, which it turned out not to be (the spot price for yellowcake, the product of uranium mines on May 5 2017 was about $50 a kilo).

The bad news is that our existing fleet of AGRs is life-limited because of growing flaws in the carbon moderator blocks in the core, caused by neutron fracturing of the graphite crystal structures. The cracks are not a problem now but they will get worse meaning there's no chance of extending the operation of these reactors past 40 to 45 years. In contrast many PWRs built in the 1970s and 1980s are getting their operating licences extended to 60 years and more, subject to some relatively cheap upgrades and parts replacements since they were seriously overbuilt in the first place.

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Re: Underground

From an NHK program I saw on the Fukushima accident, the reactor operators were turning the passive cooling system on and off as they believed that it couldn't be left on for some reason. The passive system was off when the control facility lost power and nobody knew how to tell if it was on or off and believed that it was on. Tepco had training problems as well as location and design problems. One perfect storm and it was all over.

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Anonymous Coward

Re: Placed underground you say ?

>A full sized passenger aircraft from 50 years ago is a 747, everything since then is smaller and lighter.

Simply not true....the A380 (which has 40% more floor space than a 747-8 - itself very much heavier than the early 747-100) is currently the largest passenger aircraft in regular service, though not the largest ever flown.

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Re: Underground

"No, not by a long shot"

It was for the time - it was designed to cool via convection even without pumps. The vales to allow this were not opened due to human error.

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Anonymous Coward

Re: Underground

Yep Fukusihima lost primary cooling , secondary cooling, and tertiary cooling, went into meltdown and the core stayed put in the containment .

If they hadn't been so worried about venting a bit of radioactive gas, it wouldn't have popped its roof off either.

It they hadn't been so worried about waste disposal there wouldn't have been 20 years of fuel rods stored in old tanks either.

A minor and trivial accident turned into a 'disaster' by the press, the greens and the anti-nuclear propagandists.

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Anonymous Coward

Re: Underground

Its sad that there are still people of such low intelligence in the IT community.

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Re: Wasn't Fukushima a "fail-safe" design?

You appear to have no knowledge of anything

The reactor did shut down

As it was designed to.

The decay heat is what was needed to be dealt with. A working reactors is fizzing and popping with lots of short lived isotopes that cause it to get hot even when the main chain reaction is stopped.

That is what you need emergency cooling for.

Otherwise the core melts.

As it did,

Which is why you have secondary containment to shield it.

Which it did.

which is why outside of the containment vessel, the radioactivity was pretty low.

And would have been lower still if they had flooded the thing with seawater and let the hydrogen escape, instead of trying to trap everything ..

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Re: Wasn't Fukushima a "fail-safe" design?

decay energy IS fission, just not as we know it, Jim, (chain reaction)

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Re: Placed underground you say ?

Sigh.

more variables than weight. Size. Speed.

To punch through concrete you need a depleted uranium shell, not an aircraft

Or something like this

https://en.wikipedia.org/wiki/Disney_bomb

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Re: Wasn't Fukushima a "fail-safe" design?

Christ, you really don't know what you're talking about do you?

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Re: Underground

Fukushima's only design flaw involved the (non-nuclear) emergency generators, which were flooded out by the Tsunami. If electrical power could've been restored within 48 hours, none of the bad things would've happened. The Tsunami wiped out the entire town as well. The containment vessels that were there helped keep the problem down to a minimum.

And all of the FUD about radiation from Fukushima showing up in california is just nonsense. background radiation levels from Mr. Sun would keep it below detectable levels. Seriously, it's a BIG planet!

/me got LESS radiation living within 100 feet of an operating nuclear reactor on board a U.S. submarine than on the surface of the earth, and I know this because we recorded our radiation dosage. I got 80mrem per year [whatever new-fangled measurement THAT is] from Mr. Sun, and about 60 from Mr. Reactor.

Most of the radiation you get is from the Sun. You're in greater danger if you fly a lot or get a root canal, than from any failed nuclear reactor on the planet, including Fukushima and Chernobyl, so long as you're not "right there" at ground zero.

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You can already get that with tonic and a blacklight, though.

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Re: Underground

Not really, no. There was only the one method of generating backup power, no emergency batteries, no protected hardline to bring a minimal amount of power in from the grid to run the pumps, and no passive method of circulating cooling water to keep built-up decay heat from melting the fuel if all the power went out. Not even a small auxiliary turbine that could use steam produced by that selfsame heat to directly turn a mechanical pump, turbocharger style.

And even if you consider "has external diesel generators" as a suitable failsafe, then the design may have been fine but its placement was absolutely boneheaded. Fuel tanks on top of the gensets instead of the other way round, no snorkels on the air intakes, etc. Despite it being at sea level, in a particularly earthquake-vulnerable area of a country more or less directly over a continental faultline and often beset with tsunamis.

Add to that seemingly no proper contingency plan for preventing fuel meltdown in the case of total water circulation failure (which could have happened for various other reasons anyway), e.g. physically separating the core somehow to prevent central heat buildup, or connecting external pumps, and a parent company whose main approach to dose monitoring and site safety was "write down any old shit, and if that doesn't work, run away", and you have something that only really avoided taking the #1 spot ahead of Chernobyl by luck rather than judgement.

Not to mention the weird choice of where to put the longer-term waste storage pools (right at the top of the building, where water needs a lot of energy to be pumped to and anything that leaks will piss all over the lower levels) and the lack of suitable hydrogen venting should they also start to cook off... and no proper secondary containment for the molten core and waste water should there actually be a meltdown (would, say, a protective pool of cold water built underneath and never normally used for anything not have been worth a little extra time and money to install? with enough spare capacity to hold whatever falls out of the reactor, and able to rapidly cool the individual blobs of the former core as it leaked out of the primary flask? Or at least some extra layers of concrete foundation, textured such to break up the material that might fall through? Anything that would have prevented it settling into a big ol' solidified puddle of radioactive awfulness, and stopped the reactor water leaching away into the soil?)

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Re: Underground

(Now in comparison, most smaller reactor designs can be considered inherently safe simply because of the small amount of material they contain - for one thing, not enough to make a bomb from, so there's a limit to how much havoc can be caused... these things tend to scale up exponentially, and indeed that's why they're not really as efficient in terms of ground area per megawatt.

But if they're also more modern designs internally like fluidised/pebble bed, thorium, the aforementioned molten salt, etc, then that adds an extra layer of protection that would also help a larger model, if only the people building the large models were at all bothered about building anything other than the same old shit that we know to be inherently dangerous...)

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Re: Placed underground you say ?

Including an A380 flown into it in a full on vertical dive, only just slow enough to avoid total structural breakup before impact?

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Re: Underground

Oh come on, you KNOW you're just tempting fate with a statement like that.

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Re: Underground

That's a matter for the statisticians, I think. I can't remember if there were any reports of direct casualties, but there's a lot of staff who have almost certainly received much higher doses than was originally admitted to. Including most likely the firefighters, even those in the helicopters. That's something that takes a long time to show in the population.

Of course, the tsunami itself was far more deadly, so it's a matter of comparitive harm I suppose.

Even so, like Grenfell, it could easily, and should have been much safer than it actually was. Both of them have a thread of "how could anyone so bloody stupid have been put in charge of something so crucial and fundamental?". Let's hope no-one's put polyethylene cladding on a reactor yet.

....also, I guess the judgement sort of hinges on whether you want to get into a discussion of how many people you have to move from within a roughly 30-mile hemispherical exclusion zone on a long-term basis before that is equal to one life lost in terms of stress and disruption to people's lives. Given that it's Japan, I wouldn't be at all surprised to hear of at least a half dozen suicides that could be directly linked to being evac'd from the Fukushima area.

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Re: Underground

I'm still sort of skeptical about the validity of that rating, as that's a logarithmic measure-of-magnitude scale, and it just doesn't seem to qualify for some of the tickboxes...

I mean, it didn't send a plume of vapourised reactor contents floating several thousand miles across a large part of the northern hemisphere for one thing. The water pollution is actually fairly slight, and although it's been measured and tracked with ease, that's because radiation detectors are very sensitive devices on the whole. No-one on the site died during the initial incident, no-one received such large doses that they died within a matter of days if not hours, and they didn't have to immediately forcibly bus the entire local population out of the area for fear of them succumbing to radiation sickness before the year was out.

We saw this drama unfolding over a matter of days after all... no actual release of solid nuclear material or fuel occurred, only irradiated cooling water and maybe a few gaseous decay products. The evacuations are mainly on a just-in-case basis. All the melted fuel is solidified somewhere in the ground underneath the plant, so it doesn't need a janky concrete cube to be hastily thrown up around it.

The plant isn't even necessarily unsalvageable, though hopefully they won't be fool enough to try... (he says, having a funny feeling he saw a news story about the second reactor having been put back into service already).

Some byproducts did escape, some people have had significant but not immediately lethal or crippling exposure - the effects of which will take time to show - and there has been significant local disruption as a civil protection measure. But it's not on a "hundreds if not thousands of deaths and immediate ruin of an area the size of Greater London which might last for millennia" scale.

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Re: Wasn't Fukushima a "fail-safe" design?

"permanently, before the incident" is not "in a panic after the tsunami"... a controlled, legally ordered shutdown including the cooling-off period...

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Re: Placed underground you say ?

"District heating is, by the way, a fantastic idea."

Yes, and married to ammonia adsorbtion cooling, an even more fantastic idea. (fridges, freezers and AC)

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Re: Underground

"LOL almost perfectly safely?! It was one of only two International Nuclear Events Scale level 7 events ever recorded! The other being Chernobyl."

The japanese declared it as a 7 but it never came even close to that.

If you look at https://en.wikipedia.org/wiki/International_Nuclear_Event_Scale and the actual effects it was a 4 or 5 at most, but panicmongering set in.

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Re: Wasn't Fukushima a "fail-safe" design?

"decay energy IS fission, just not as we know it, Jim, (chain reaction)"

There's more to it than that.

Uranium oxide - like most ceramics - is a LOUSY thermal conductor.

In PWRs the centre of fuel rods (which is where most of the fission takes place) usually sits around the doppler limiting temperature of 1100C whilst the outside is cooled to 400-450C by water. You could stop all fission and simple thermodynamics will ensure you have substantial quantities of heat needing to be dumped until the rods reach equilbrium. Secondary fission is minor in comparison.

Think of it as a 50MW heat source and thermal block surrounded by _very_ good insulation and then a water jacket, where you're extracting heat from the water. It takes quite a while to get rid of all the residual heat when you turn the source off.

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Re: Underground

" I guess the judgement sort of hinges on whether you want to get into a discussion of how many people you have to move from within a roughly 30-mile hemispherical exclusion zone on a long-term basis before that is equal to one life lost in terms of stress and disruption to people's lives."

Especially when not moving those people would have exposed them to extra radiation equivalent to 2 chest xrays per year (by way of comparison that's about the same as a single 4-5 hour passenger jetliner flight above 25k feet)

Most of the hysteria associated with nooo-cle----arrrrrgh accidents has no basis in fact and is informed by B-grade science fiction movies.

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Re: Underground

and it wasn't failsafe. it needed active cooling.

Fukushima is an absolute tribute to basic good design.

in the end its last safety feature - secondary containment and a core meltdown pool - did their jobs.

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like the Tritium that leaked from the Vermont Yankee nuclear plant? Not a problem (once they found the pipes; evidently someone misplaced th diagrams); it all just leached away into the Connecticut River somewhere.

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They can have my back garden

and I'll charge the neighbours for keeping their lights on ...

AtomKraft ? Ja bitte !!

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SMR's are the way to go but using Thorium and Molten salt (FLibe) ideally as burner types. Cos using conventional PWR type reactors only increase the vast amounts of plutonium and actinides we already have already but a Flibe burner will dispose of them. Leaving a tiny proportion of the waste behind which can be fuelled in another burner and the rest like CS-137 will decay way in 300 years.

Over 100, probably 150 tons of waste Plutonium and growing in the UK along with the other transuranics should be fissioned as energy rather than the mad folly of trying to store it for tens of thousands of years by vitrifying it into glass..

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"...the mad folly of trying to store it for tens of thousands of years by vitrifying it into glass.."

I remember watching a documentary on Windscale/Sellafield, and back in t'day they just dumped the spend rods in to a swimming pool that was on site.

That's folly.

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Anonymous Coward

vitrifying

The plutonium (and other "useful" products) are not vitrified - it's only the (approx) 3% of actinides that gets vitrified.

However, I do agree that it would be better to burn as much as possible as fuel.

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Anonymous Coward

Magnox fuel rods have to be cooled before they can be reprocessed.

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Somewhere along the line I read that the reason why Uranium 235 fission reactors got the nod in the 1950s was because the military of the time considered plutonium (handy if you've got bombs to build) production high priority. Which seems reasonable enough given the recent history of the time.

So, yes, in context plutonium was very useful indeed.

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"SMR's are the way to go but using Thorium and Molten salt (FLibe"

Britain's Carbon Dioxide cooled reactors have an excellent safety design and record.

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I remember watching a documentary on Windscale/Sellafield, and back in t'day they just dumped the spend rods in to a swimming pool that was on site.

The correct term is 'cooling pond', and they're still there. It's not a swimming pool because if you tried to swim in it, you'd die - not from the radiation which is very well attenuated by water, but from the bullet wounds.

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But they can't be left too long 'in soak' because Magnox corrodes under water.

All spent fuel is initially cooled underwater before it is either sent for reprocessing (usually on flask trains which contain big steel tanks of water), or moved to permanent dry storage usually on site.

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Quite right - at least in the UK.

The first two Magnox plants at Calder Hall and Chapelcross were essentially built to supply plutonium to the military. They were publicised as providing power to the grid, but their contribution was very small. The Magnox design was especially suited to plutonium since fuel elements could be removed from the core after a very short burn of 90 days or so which ensured there would be a high ratio of 'useful' 239Pu to 240Pu in the spent fuel. 240Pu is not wanted in weapons since it occasionally spits out a neutron which can cause predetonation of the bomb during implosion.

The later, much large Magnox stations were civilian and IIRC all of their spent fuel was put through a civilian reprocessing cycle.

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Unfortunately the economics of the AGR were less excellent which is why the CEGB switched to the PWR.

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"I remember watching a documentary on Windscale/Sellafield, and back in t'day they just dumped the spend rods in to a swimming pool that was on site."

Was that the one on BBC4 last month? they did a whole night about nuclear - still on iPlayer I believe and well worth a watch.

They went into detail about the outdoor ponds that they dumped everything in - basically the number one concern was producing enough material for the h bomb so nut much thought was put into the mess left behind - which they are cleaning up now.

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Anonymous Coward

think you would die evetually and not from the bullet wounds - especially if you swallowed the water...

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re:they did a whole night about nuclear

The program about the UKs fusion (H-bomb) story was good too

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Anonymous Coward

>Was that the one on BBC4 last month? they did a whole night about nuclear - still on iPlayer I believe and well worth a watch.

Definitely - Cockcroft's Follies are an interesting warning from history (aside from the terrifying amount of waste that remains).

The follies are a nice example of how 'nay sayers' on nuclear safety are treated too - even a Nobel prize winner was ridiculed. The death toll in 1957's reactor fire would have been huge without them (only ~1000 mortalities are attributed - thyroid cancer etc which sounds a lot, but I guess coal power killed countless more in the same period)

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Boffin

> but from the bullet wounds.

XKCD reader?

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Coat

think you would die evetually and not from the bullet wounds - especially if you swallowed the water...

That's the thing about water though. Every bit of it is contaminated! Why, everyone who drank water anywhere in 1850 has since died!

(That's also the thing about statistics)

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Re: vitrifying

Yes of course the Pu isn't in the mix per se - but the current chemistry we used for reprocessing is almost as flawed as the silly designs of reactors everyone made largely in the quest for the bomb.

The Purex process produces chemical by-products which are even more toxic than what comes in.

Before the work does eventually go fusion one day and not in my lifetime we need to deal with the mess that's been left behind and chemically and efficiency wise its using FliBe salt. Not water or air soluble and a very stable compound at normal temperatures and when hot a much better efficiency match for a gas or even supercritical CO2 turbines than the current steam. The CO2 turbines are a fraction of the size too.

Even stored it will leak tritium - but tritium with a half life of 12 years decays to Helium-3 which is certainly going to an extremely valuable resource powering fusion reactors. Why mine the moon for it?

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