
What Is Called Nuclear Waste Is Mostly Fuel for Molten Salt and Fast Reactors - rbanffy
https://www.nextbigfuture.com/2019/06/what-is-called-nuclear-waste-is-mostly-unused-fuel-for-molten-salt-and-fast-reactors.html
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philipkglass
This is true only if you ignore costs. It falls apart as soon as you include
market pricing or any other reasonable resource allocation mechanism.

It's like pretending that the _liabilities_ represented by a huge coal ash
pond are actually an _asset_ , because if all the aluminum and silicon in the
ash were purified and sold it would be worth a lot at present prices. The
problem is that the cost of turning the waste into a salable product is higher
than the market price. So it is still in fact a liability.

Under present and foreseeable economic and technical conditions, the asset-
value of spent nuclear fuel does not exceed its liabilities.

~~~
phkahler
But the "spent" fuel is already a liability that no one has figured out how to
get rid of.

~~~
philipkglass
Trying to permanently get rid of spent nuclear fuel under present and
foreseeable conditions costs more than monitored dry cask storage for the
indefinite future. A determination to permanently get rid of it despite the
lower cost of once-through fuel cycles is a determination to take a modest
liability and make it worse.

~~~
irq11
...unless you count the risks of something bad happening.

That’s always the unspoken actual debate when it comes to nuclear energy:
what’s the probability of the worst case, and how does it affect the amortized
cost?

We’re terrible at doing this calculation in other areas (e.g. terrorism vs.
the cost of security theater), so it’s not especially informative to talk
about the status quo. Clearly, we believe it’s cheaper to just store the
stuff, or we wouldn’t be doing it. With nuclear energy, the exceptions matter
a lot.

~~~
philipkglass
Both present once-through fuel cycles and "burner" reactor concepts produce
fission products in proportion to energy generated. The short and medium lived
fission products are the most intensely radioactive and dangerous byproduct of
nuclear fission for the first few centuries of waste storage. The advantage of
a burner reactor from a waste perspective is that it can consume longer lived
actinide waste products like neptunium, plutonium, and americium. A burner
reactor converts these actinide wastes into more intensely radioactive but
less-long-lived fission products. (Additionally, some much longer lived and
less intensely radioactive fission products like technetium 99 are also formed
in burners and conventional reactors.)

This is to say that even if you place a high premium on avoiding environmental
releases of radioactive materials, there is no appreciable benefit from burner
reactors on a human time scale. The overall radiotoxicity inventory that needs
ongoing management is nearly the same for both burners and once-through
reactors for 200+ years after the fuel is done with. Further, fuel
reprocessing facilities are themselves more likely to leak fission products
into the environment than dry cask storage is.

~~~
littlestymaar
> Further, fuel reprocessing facilities are themselves more likely to leak
> fission products into the environment than dry cask storage is.

But these fuel reprocessing already exist and the waste are currently already
reprocessed to make MOX fuel, at least in some countries (France, UK, India,
Russia and Japan).

~~~
philipkglass
Yes, and those plants release more becquerels of radioactive material into the
environment when they reprocess fuel than would be released if the fuel
elements were left intact in dry storage. I'm not saying that reprocessing
plants release a _dangerous_ amount of radioactive material. I'm saying that
reprocessing makes things worse if your top priority is to prevent releases of
radioactive materials into the environment. It also makes things worse if your
top priority is to make nuclear-generated electricity affordable.

------
curtis
Nuclear waste is also mostly fuel for hybrid fusion-fission reactors. From
Wikipedia[1]:

> _Hybrid nuclear fusion–fission (hybrid nuclear power) is a proposed means of
> generating power by use of a combination of nuclear fusion and fission
> processes. The basic idea is to use high-energy fast neutrons from a fusion
> reactor to trigger fission in otherwise nonfissile fuels like U-238 or
> Th-232. Each neutron can trigger several fission events, multiplying the
> energy released by each fusion reaction hundreds of times. This would not
> only make fusion designs more economical in power terms, but also be able to
> burn fuels that were not suitable for use in conventional fission plants,
> even their nuclear waste._

As an extra advantage, such a reactor would be _subcritical_ (similar to a
_Accelerator-driven subcritical reactor_ [2]) so it would never be at risk of
a melt-down.

On the other hand, I'm pretty sure that such a reactor would still be a
proliferation risk like fission breeder reactors.

[1]
[https://en.wikipedia.org/wiki/Nuclear_fusion%E2%80%93fission...](https://en.wikipedia.org/wiki/Nuclear_fusion%E2%80%93fission_hybrid)

[2] [https://en.wikipedia.org/wiki/Accelerator-
driven_subcritical...](https://en.wikipedia.org/wiki/Accelerator-
driven_subcritical_reactor)

~~~
jhayward
> _so it would never be at risk of a melt-down_

This is a misunderstanding of what a melt-down is. In every case we know of
involving commercial reactors, fuel melt-down happened _when the reactor was
non-critical, completely devoid of fission_.

Meltdown happens when the heat generated by decay of products produced when
the reactor was critical cannot be removed fast enough, such as when a cooling
system fails or coolant does not cover the fuel modules.

Any reactor with solid fuel and a high enough energy density will have a
meltdown possibility, unless it is somehow using a reaction chain that
precludes the production of high-activity fission products.

~~~
amluto
Regardless of precisely what a “melt down” is or whether this was the
appropriate term here, the Chernobyl explosion was caused by an excessive
amount of fission output in a super-critical reactor. As I understand it, in a
fission- or accelerator-driven reactor, if you turn it off, fission stops
rapidly. Decay heat will remain, but that’s a smaller amount of output power
and is presumably a good deal less dangerous.

~~~
littlestymaar
That's way enough to cause an accident though, see Three Mile Island and
Fukushima.

------
Tharkun
"Mostly"? It's not like spent fuel is the only kind of nuclear waste...there's
also tons of radioactive building materials, contaminated water and whatnot.
Probably not as dangerous as (spent) fuel, but radioctive and voluminous
enough to be a problem.

~~~
TeMPOraL
> _there 's also tons of radioactive building materials_

It's a rare case where this is an accurate statement, because a typical
nuclear power plant produces a dozen or two tons of waste _per year_. Take a
look at this observation until it sinks in just _how little waste_ that is.

~~~
Tharkun
How heavy are the buildings housing the reactor? How much of that material is
radioactive/unsafe after a couple of years of operation?

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orwin
This article is misrepresenting the truth. Maybe the majority of the waste
mass is really uranium (i doubt it, but i'm no expert), but from what i heard
from an EPR engineer, the volume of this waste is in fact tools, clothing,
used part that have been replaced and stuff like that. Not hard to take care
of, and waste that contain very low level of radioactivity, but this should be
the majority of nuclear waste, and this is not "mostly fuel" in any case.

Please be precise.

~~~
pjscott
A more precise version of the title would refer to "high-level nuclear waste":

[https://en.wikipedia.org/wiki/High-
level_waste](https://en.wikipedia.org/wiki/High-level_waste)

------
inflatableDodo
Which is why the UK was importing nuclear waste for a while. Whether it is
economic is another thing. Is hard to tell from the UK experience, since that
collapsed due to faking data for fuel pellets that were being sold to Tepco.

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LargoLasskhyfv
What is the relation of cladding vs. content in a fuel rod? AFAIU any used
fuel rod needs to be disassembled to be freed from its cladding, and only then
can be reprocessed by whichever means to make new fuel rods with new cladding,
which leaves the old cladding as irradiated trash. Am i popping a bubble
there? Or is there a way to somehow melt that stuff into new cladding. Anybody
thought about that? I mean, just look at the pictures in

[https://duckduckgo.com/?q=Fuel+Rod&t=ffsb&iax=images&ia=imag...](https://duckduckgo.com/?q=Fuel+Rod&t=ffsb&iax=images&ia=images)

or

[https://en.wikipedia.org/wiki/Nuclear_fuel](https://en.wikipedia.org/wiki/Nuclear_fuel)

Anybody thougt about _that_?

Edit: I mean even IF used in molten salt reactors where there are no rods and
therefore no cladding, what happens with the old cladding? That's not just
some tinfoil where you could make hats out of it!

~~~
nickik
Well the cladding is radioactive but to a far lesser degree then the fuel
itself. Its waste but lower level waste as it doesn't contain the most long
lived elements. I mean, they will be their anyway, so your not creating more
waste buy having the old rods.

Also, most molten salt reactors wouldn't use fuel rod. And the ones that do
would be different compared to those in PWR so reuse is unlikely.

Edit: See here
[https://youtu.be/TvXcoSdXYlk?t=1828](https://youtu.be/TvXcoSdXYlk?t=1828)

------
nickik
Its fuel for any kind of reactor. The process is a bit easier if you make salt
fuel.

Its makes sense if you also get money to consume the waste otherwise its
cheaper to go with freshly mined uranium. Or if you are interested in a fuel
mix that is easier to obtain in spent fuel.

Edit: For those interested, one of the company engaged in the Canadian
regulator process is proposing this:

[https://youtu.be/TvXcoSdXYlk?t=1828](https://youtu.be/TvXcoSdXYlk?t=1828)

MSR Reprocessing - Sylvie Delpech:
[https://www.youtube.com/watch?v=fBEjys1SKCQ](https://www.youtube.com/watch?v=fBEjys1SKCQ)

This is a talk by the company that is furthest along the timeline of bringing
molten salt to the market and he talks a little about their fuel as well (they
don't do reprocessing):
[https://www.youtube.com/watch?v=l8QVxYrQRxA](https://www.youtube.com/watch?v=l8QVxYrQRxA)

------
surfmike
How much waste do the molten salt and fast reactors create?

~~~
nickik
It depends. There are a variety of differences.

In terms of volume its far less then with a PWR as there you have lots of
other stuff in there as well. For the same amount of power, the waste from a
MSR will much less and would have a better waste profile.

However beyond that, it all depends. There are many different designs,
different inputs, different burn rates and so on and so on.

------
m0llusk
And monkeys might come flying out of my butt except in our post enlightenment
world we need facts, observations, and reasoned evidence to support claims.
Molten salt reactors have so far proven extremely difficult to build and
operate and tend to leak molten salt. Fast reactors are mostly not a thing at
this point. Making complex technologies work means not only overcoming
technical challenges but doing so in a way that constrains both costs and
risks which so far has proven to be extremely difficult.

~~~
nickik
> proven extremely difficult to build and operate and tend to leak molten salt

The only are 2 molten salt reactor ever built and neither one had a leaking
problem. In fact, they would even be self sealing as the salt will cool down
rapidly and seal the hole. If you have a rupture in the whole core, the
spilled out salt would be captured in a pool and harden, it would be contained
in the nuclear site boundary. This is the advantage of high temperature and
salt. The temperature differential to the environment that the cooldown is
very rapid.

Compared to PWR, the danger of a a molten salt reactor is incredibly small.
There is no high pressure and steam, thus no explosion that can transport
stuff like zirconium outside of the nuclear boundary.

Its also false that they have been extremely difficult to build. The Molten
Salt Reactor experiment was operated and built by small time at a tiny
fraction of the budget that were spent on many of the other nuclear reactors
built at that time. They are far easier to build then a PWR in terms of
complexity of and scale involved. The Molten Salt reactor experiment (the
first ever molten salt reactor) was one of the fastest nuclear reactor was
ever built.

The reason we don't have them has more to do with the history of nuclear
technology. The Navy focused on PWR for ships (as makes sense=, those were
commercialized with big investment of government and industry and were the
most mature by far. Molten Salt reactors were in development by the Navy and
were discontinued when rocket technology made nuclear bombers unneeded. After
that the inventor of molten salt reactors only got a tiny amount of money to
continue his research for a civilian reactor.

The big nuclear players didn't really care about building new reactor types as
they had lots and lots of orders of the production designs they already had.
There were only a very small number of people who were educated about what a
molten salt reactor or how it worked. It required a somewhat different skill
set (the inventor was a chemist) and neither government nor industry had a
taste for commercialization at that moment. It didn't help that the inventor
basically made himself unpopular with the regulatory agency when he claimed
PWR were unsuited for civilian use.

When regulation changed because of TMI and Chernoyl the nuclear companies had
their hands full with rebuilding all the plants according to new regulation to
keeping the existing fleet ruining (and finishing project that were being
built) and by that time the regulation had changed so that it was basically
impossible for any new type of reactor to be licensed. In the US the
technology was hard coded in to the regulation and made it impossible to
deploy a new type of reactor in a commercial way. Since then hardly any new
reactor type has been built or tested as you can not get fuel for anything
beyond a tiny research scale reactor without passing full commercial
regulation.

Development of pretty much all serious molten salt fuel has now moved to
Canada as the regulators there have not hard coded specific technologies and
the regulator investing its own resources to get threw regulation of such a
reactor. In the US, you would have to pay the regulator to evaluate your
design with no timeline or guarantee that would even allow it at all. Meaning
you would have to design a full commercial reactor before the regulators even
tell what you would need to do to convince them about the reactor. Meaning you
potentially spend 10s of millions on paying the regulator before the actual
regulatory process could even start, as you would have to finance the
development of a regulatory framework for molten salt reactors.

Thankfully the DoE has realized this now and they are working hard at chaining
their approach and congress is for once actually engaging in a bipartisan
effort to improve the situation. See this talk for more information about
government efforts:
[https://www.youtube.com/watch?v=p1lkDRX2huM](https://www.youtube.com/watch?v=p1lkDRX2huM)

~~~
shereadsthenews
You can't wave away the remaining challenges of a molten salt reactor. It is a
legitimately difficult materials science problem to operate a liquid salt pump
loop operating at ~1000K and under high neutron flux.

It's also not a super-great explanation that a major accident will just cause
the salt to flow into the holding tank. What if the holding tank is full of
water? Why would it be full of water? I don't know but the planet is
absolutely filthy with water and "the basement is unexpectedly full of water"
has happened to almost every building humans have ever built. These are
supposed to be installed _entirely_ underground, enhancing the danger of water
intrusion.

Finally there is still the challenge of continuous processing of the liquid
fuel, to remove ash, add fissile materials, and separate gases. Nobody knows
how to do this. Nobody has explained what to do with all the radioactive
krypton etc.

~~~
bassman9000
_It is a legitimately difficult materials science problem to operate a liquid
salt pump loop operating at ~1000K and under high neutron flux._

And so it's containing the fusion plasma, yet billions are poured into
material research. And hastelloy N is already invented.

~~~
nickik
Hastelloy N will not be used by any of the companies building commercial
reactor. Hastelloy N would have to go threw a whole lot of regulation to
allowed to use in modern reactor.

The data gathered on its properties would not be sufficient for a modern
regulator, and such a qualification would take way to long. Also, there is not
really a supplier for commercial Hastelloy N.

Their focus is on using 'regular' nuclear grade materials that have already
been approved. This is THE single most important focus of those reactor
design. In the choice of containment, reactor type, salt solution and so on,
they all picked sub-optimal things in order to make it threw the regulator and
have a existing supply chain.

