Tip:
Highlight text to annotate it
X
I'd like to start us off by asking Steve -
we were talking about rare-earths -
and what was it, 100,000 metric tons per year?
Oh, I'd have to look back at the slides, but we need thousands and thousands -
thousands and thousands of metric tons.
- and it is going to keep increasing.
and the tie-in to this has to do with fission products
and they contain these rare-earths?
The fact is that thorium is mined coincidentally with rare-earths
and we currently have a bottleneck here in the United States, because of the thorium issue.
And, I just wanted people to understand, and underscore the importance
both currently and in the future of rare-earth elements in general.
I'm going to talk about how one throws away rare-earths.
They may be very valuable, but they do represent something like a third
mass-wise of the fission products that are created
by almost any kind of nuclear reactor involving fission.
It may be possible to find a customer for these things.
I suspect as much as we're mining out of the ground,
or will be mining out of the ground,
that the recycling of fission products - certainly this kind of fission products -
certainly this kind of fission products -
will be probably hard to sell.
If we implement any sort of
truly sustainable nuclear fuel cycle we are going to have to reprocess stuff.
Maybe that's not the correct word.
We will have to clean up the waste -
the fuel-salt stream one way or the other
and that will involve chemistry.
There will be chemical waste produced, and a good deal of it.
Depending on how one implements the fuel cycle it can be a tremendous amount.
This is one of the legacies of the way nuclear power came to be,
and it is especially troublesome in this country.
It is troublesome in Russia too, but they don't get quite as hyper about things as we do.
One of the issues that nuclear power has - and it's always brought up and you get people talking about it -
"Should we do this?"
- is the waste thing.
The DOE admits right now its projected costs
for cleaning up its own reprocessing waste at its own facilities now,
is something like 200 billion dollars.
Now wouldn't it be nice to have a couple percent of that
to spend developing a a whole new nuclear fuel cycle
that doesn't create this kind of waste?
It would be nice.
One way or the other, we are going to have to clean up after ourselves
and if we're going to be accepted in this future world
we are going to have to show upfront that we have addressed this already.
We know how to do it.
We know how to do it in a way that is acceptable.
That is, a decision maker at this point is not going to criticize you
because you decided to make some mineral out of it that you can't make.
Okay, why commit to a waste form?
That is, once you have the waste, you need to be able to
make something into it - which is a waste form.
A waste form is understood to be something that
if you dispose of it, put it in a hole in the ground,
it is not going to dissolve if groundwater happens to break into this thing.
It shouldn't be a powder, it shouldn't be a liquid, it shouldn't be readily dispersable.
It should be something people feel comfortable -
If necessity says that we never have a Yucca mountain
you could still leave it wherever you generate it basically.
It has got to be tough stuff.
Wind can't blow it around, and water can't dissolve it.
And, we need to commit to it.
As I refer to the 200 hundred billion dollar legacy we are facing right now.
It probably will not be completed.
I just can't see us in this country, the way it is right now,
spending 200 hundred billion dollars
on the kind of waste that has been generated in the past.
But, we do need to commit and it is one of the things that's been holding us back.
Incidentally that is a heck of a good book: "Atomic Awakenings" [James Mahaffey, Pegasus, 2009]
My assumptions are here are that waste immobilization will be a part of the system.
Whatever it is we get behind and decide we are going to do,
we're going to tell everybody we're going to handle waste right up front.
That's what the Europeans do with their modern reprocessing facilities, they go clear to waste forms.
When they dissolve the fuel with a few days
they've got a waste form already there - they've made glass out of it.
It will be completed not 40 years down the future,
not 30 years away - it's going to be completed quite soon.
Once the stuff comes out of the reactor
we're not waiting for our grandchildren to do it.
It's got to be done in real-time - almost real-time, within 5 years after removal from the reactor.
And, that's fine because then you are getting down into the 30-year half-life stuff.
The initial burst of fission product heat is over with.
Five years is a reasonable time.
Your disposal form must meet stakeholder expectations.
Again, wind can't blow it around and if water gets to it, wherever you put it, it's not going to dissolve.
No great leaps of faith.
If we're going to convince people we are going to do this
we can't assume that there's going to be breakthroughs
that people have been looking at for 30 years - haven't been made yet.
It's got to be a technology that's waste treatment to the waste forms
that we could do now if we had the waste.
And, disposal forms are going to stay in-situ for some time.
That's why you want a good one.
If it never goes anywhere -
no tragedy.
Characteristics: The product has got to be a good quality product -
can't be too big.
It has got to be durable.
The process doesn't want to generate a whole bunch
of secondary waste streams that are worse than, or harder to get rid of
or more expensive than the initial one.
And, the key to that, is recycle.
Recycle any chemical that you use in your process.
Now, in LFTRs, based on fluoride - that chemical would be fluoride.
That's the key to this.
If you want to make this work,
recycle has to be a part of the system.
It is something the DOE has totally ignored.
Okay, IFR: There are two ways of implementing it.
We're here to talk about the other one
but IFR has got a big head start on it.
Basically there are two kinds of waste generated, one is a salt waste.
We would generate a salt waste with LFTRs too.
It's just that, we would probably have a fluoride based salt waste,
the IFR uses a chloride based salt waste.
Again, it's a molten salt. Their reprocessing involves a molten salt,
and it's chloride based salts -
and the waste that they are going to throw away, the actual stuff that's in the
cans of high-level waste that is being thrown away,
If you look, at it - it's 95% [by mole] alkali metals -
mostly lithium and potassium.
It has some sodium, and some cesium, but it is mostly alkali metals -
not fission products.
This is as concentrated as the waste ever gets, and it's 95% other stuff already.
The point I'm trying to get across here is
this disposal problem is an alkali disposal problem
with 5% fission products thrown in along with it.
So, your waste form has to be able to handle alkali [metals].
LFTR waste:
If you have thermal - epithermal reactors like they will probably be -
moderated in some way or another,
then the salt will be a fluoride salt (FLiBe probably) -
but the waste will be a mixture of fluoride salts.
And, if we implement a fast reactor for one reason or another, it would be chloride salts.
The waste streams would be very similar to those for your IFR - but they're salts.
Okay, the Basis [of a] LFTR waste stream, this is the basis I use,
because it is a source where I can get definite numbers
for how much is that to be produced by a GW worth of electricity production over a year.
[It is] about 4 tons of sodium and magnesium fluoride pellets,
containing some fission products, mostly as fluorides.
You are going to have 4 tons of that stuff,
and it's mostly sodium fluoride.
And, you're going to have 1 ton each of lithium fluoride, plus nonvolatile fluorides.
This is from a distillation process.
You have a separation,
so that you can put the useful salt back into the reactor.
You are getting a ton of this stuff.
And, then you have aqueous waste.
The aqueous waste turns out to be - mostly potassium fluoride.
That's what it will actually be.
It is from the scrubbing solution which absorbs HF, makes potassium fluoride (KF).
So, your waste is again 95% (molar) alkali metals,
in this case as fluorides.
That's what your waste actually would be.
Well you've got to try to make a rock out of it - something that's durable,
something doesn't blow around on you.
Glass -
is what you want to make,
and the process to make glass is called vitrification.
When folks talk about disposing of halide-based waste,
when they think chloride, they think "Ah, sodalite",
because out there mother nature has made a mineral which
contains some chloride which is relatively insoluble.
Sodalite jumps into the minds, so that's what they base their waste form on.
That's what the DOE did.
Folks developing the IFR - liquid metal fast breeder reactor system
their whole waste form development program was
based on the assumption that they are going to make sodalite.
In the case of fluoride based salts, the first thing that comes to mind,
apparently it's come to mind several times -
is to make this crystalline mineral called fluorapatite.
Nice mineral. The problem is it's 3.7% (by weight) fluoride,
and much less than that weight-percent of other stuff.
When you look at the overall -
By the time you ended up making this stuff your waste form would
contain less than 0.5% by weight - fission products.
So, you have to make 200 tons of stuff to get rid of one ton of fission products - very dilute.
They can't contain much of what you're trying to throw away.
The ceramic waste forms - you are trying to make a crystalline waste form -
that doesn't contain much waste.
Glasses:
Glasses are basically a solvent.
You create a insoluble matrix that you can put stuff into it.
You can put just about anything into it.
Up to about maybe 20% to 30% by weight of stuff can go into a glass and is still a glass
The only way that stuff can get out is if the glass itself dissolves.
So, you have to dissolve the glass to get the stuff out.
Okay, and what dissolves most easily in a glass made of alkali?
Alkali.
So, it's really the making of a waste form for waste like this,
the goal is to keep alkali from leaving.
Because if the alkali leaves, then other things - the stuff -
the plums that are in the pudding,
will also get out.
If the alkali doesn't leave, then everything is good - the fission products are in it.
So, what we're trying to do is - immobilize alkalis in some way,
and glasses do a fine job of that if you do it right.
And, they're very simple to make -
all you do is throw stuff in a pot and melt it.
You're not trying to create conditions where a specific mineral is formed.
You are throwing stuff in a pot and melting it.
That's what vitrification is. It is pretty simple -
really simple.
To make all this work, the halide -
there's no reason to throw away the halide, that is certainly not anything as expensive
as a high-level waste form
They're not particularly toxic.
If they are there as ions they are not toxic at all.
The fluoride ion - you put it on your teeth.
You eat it as a salt.
It's easy to make it -
to convert fluorine and chlorine to those forms.
They are not toxic.
Are they radioactive? They are not radioactive.
So, why spend a billion dollars per cubic meter to throwing away fluoride,
especially when you're using it in the process?
Okay? So, recycle the stuff. There's lots of reasons for doing it.
There's glasses: You are going to make glass.
There are three different kinds of glasses out there.
There is borosilicate glass which
the DOE has focused on and awful lot,
Some cases make sense, other cases makes less sense.
Russia focused on aluminophosphate glass - for the same waste.
Tremendous amounts of both of those glasses have been made.
And, most recently in the DOE complex -
because of an admission by the DOE
that maybe borosilicate doesn't work very well for some of DOE's problems
They have been studying iron phosphate glasses,
and there's good reasons to study them.
Fe-P that's iron phosphate glass.
It is a better choice than borosilicate -
easier, simpler, cheaper to make,
and the reason is that phosphoric acid is a fairly strong acid - it's not like silica.
Phosphoric acid is a strong acid.
So, if you put a chloride salt in with phosphoric acid -
the chloride comes out. Recycle is dead-easy then.
The waste form making process does your separation for you.
And, the separation comes off as HF, or in the case of chloride, HCl.
HCl is an acidic acid.
It is easy to scrub, easy to recycle, easy to put it back into your process.
This is how I do stuff.
You can't get funding to do research -
I'm ex-DOE - if I were DOE they still wouldn't fund me,
so I do it at home.
And, the drivers are quite different.
I'm not trying to just spend the money, I'm trying to solve the problem.
So we have made about 50 glasses altogether, both direct and indirect.
"Direct" meaning that you throw the stuff in the pot, melt it up and there's your product.
"Indirect" means you do something to the stuff before you throw it in the pot and melt it.
Indirect means that I've done a halide separation up front.
Specimens were tested by DOE's own leach protocol.
you grind the product into fine particles,
put it in boiling water for a week and then determine what's in the water.
And, you compare it to DOE's own standard for high-level waste glass.
That's what a glass looks like, its the stuff in the center of my mortar.
There is a glass and the crucible it was made on.
I don't have enough time to show you the furnace it was made on. This is the "Direct VIT".
"Direct VIT", that means everything thrown into the pot.
On the left-hand side, we have iron phosphate and sodium fluoride.
The other ingredients for the iron phosphate glass are
phosphoric acid and iron oxide,
put in that, you melt it up you can see it's not very shiny.
Okay, if you do the same thing with chloride,
sodium chloride as opposed to sodium fluoride, you get those nice
lovely, shiny, glass that looks more like a glass.
For comparisons, we have got some melted EA glass -
a borosilicate glass, also containing iron.
The two on the right are true glasses, the one over there
is a mixture of glass and ceramic - well actually a crystalline material.
That's what they look like.
These two are glasses and that's a glass-ceramic over there.
Characterization:
You look at it - it tells you a bunch - is it clear or is it not clear?
Is it shiny or is it not shiny?
Mass - you weigh everything going in, you weigh what's coming out,
does it agree with what you would like it to?
That is, the assumption is - are you driving off all the halide,
because you can tell that.
Halide comes off, it has to be replaced by something else,
which weighs is something else so,
it either meets expectations or it doesn't.
And, then of course the leach test,
grind it up,
put it in hot water and see how much stuff is in the water -
and that's very easily done.
I said this is all about retaining alkali metals.
When alkali metals dissolve out of a glass and go into water they create a salt solution.
The electrical conductivity of a salt solution tells you how much salt is in it,
and that's why I'm able do this stuff at home.
And, you can compare it to same thing that you get with
the EA glass that you purchase from the DOE.
Chloride salt based waste:
I got the stuff published - the stuff I did in my basement -
right down there. In fact it's coming out this month.
The june issue of Nuclear Technology has my paper in there.
This one addresses the chloride waste
That would be a fast LFTR or IFR waste.
It's very easy to do this stuff because all you have to do is throw everything in a pot,
The HCl comes out, there's no prior separation involved, you get a nice
glass and the glass is better than DOE standard - very simple to do.
Fluoride based salt waste - the direct process
creates a glass that has crystals in it -
crystals containing leechable fluoride,
and it turns out that's not a good product.
Because, you can come up with a scenario that is realistic -
if you put the stuff in the ground and water gets to it, the water is moving,
it is going to dissolve pretty quickly.
The bottom line is, you have to separate out the bulk of the fluoride before you make a glass,
if you are going to throw away this stuff.
But, it turns out it's easy to do.
The fact is that the direct process doesn't work very well.
Nitric acid increases vapor pressure,
I've done it quite a number of times.
Most important in this process - adding nitric acid, driving off all of the HCl or HF.
It is easy to recycle fluoride,
and it's easy to destroy the NOx.
Because, NOx is so reactive, as is nitric acid, that you can convert it
to nitrogen chemically - very simply, very cheaply,
so it doesn't create an incidental waste - and it's cheap to do.
That's how I did it, this is large-scale.
My small-scale ones were much smaller than this,
but this is an aluminum frying pan with Teflon on it.
You put sodium fluoride in it you add nitric acid to it, you heat it up and you've done your separation.
Even the DOE could do this for less than a billion dollars.
These are what the products look like.
Again - on the left side over there is the direct one
containing the crystals of water soluble stuff.
over here [on the right] is a true glass which has very good leech properties.
Leech test results: Over there on that axis as we have the fraction of alkali
which leeches in by whatever period of time we have at the bottom.
The PCT test, DOE's standard test, that's 7 days at 90° and so forth,
their glass, the reference - about 16% by this test, goes into solution.
16% of DOE's glass has dissolved in that time, releasing its alkali into the water.
These glasses that you create this way are about 8 times better than that.
It's very simple, and it's very cheap. We can do this.
Off gas treatment:
Stuff comes out of the pot when you do these boil-downs and when you make glass.
What you want to do is filter them out of the air and you want to capture
the fluoride and you want to capture any particulate matter that comes out,
and any volatiles or fission products.
You trap them and you destroy the NOx.
Three steps you want to do: Capture the fluoride so it can be recycled,
destroy the NOx and capture the fission products.
The way to do it is with hot carbon.
This is a reactor, the gas comes in the bottom containing
nitric acid and HF, NOx,
fission products, and steam.
Remember, this is water, nitric acid and HF.
These gases are going to be coming out of that thing.
If you react them with carbon at about 500°C,
the carbon will quantitatively reduce everything to nitrogen
and all of the oxidised nitrogen species will go to nitrogen gas.
But the fission products,
these are metal fluorides for the most part - are reduced right down to metals.
And, the metals are not volatile, they stick to the carbon.
and they will stay in there until the carbon is burned up.
when the carbon particles get small enough, they blow out
and you can capture them in a downstream cyclone filter.
So, the fission products will be capturable.
A small amount will be mixed up with graphite,
and there is a fine dust - a small waste stream.
This is a system where salts go in the one side and recycled water goes in this side,
fluorides are taken out the bottom, converted to
sodium fluoride, one of the main reagents used in the process
or to FLiBe, or whatever it is you want,
and they can be recycled,
and then all of the fission products all end up in glass.
There's several ways to deal with this carbon-fission product mess,
but probably the the best one is
take this stuff, burn off the residual carbon on it, and put it back into the melter.
With an efficient recycle loop, you can even get technetium
and iodine to stick in glass quite efficiently.
The folks at Catholic State University proved that.
Summary: we can't keep kicking this waste can down the road.
We certainly don't want to start off
trying to sell people on LFTRs unless we've got an answer
for the waste question.
And, I think we have an answer. It's pretty easy to vitrify this stuff if you're willing to recycle -
and we should want to do that anyhow.
Vitrification:
If you suggest we are going to do anything but turn it into glass,
everybody's gonna their hackels because
vitrfication is what the world does with high level waste, so we can do it too.
Halide recycle makes it practical,
using the assumptions from that Oak Ridge paper,
about the amounts of salts and the types that were created,
We are talking about a GWyr worth of electricity
generating 6.5 cubic meters worth of glass
which should be a little bigger that this, if this were a cube -
but not much bigger than this.
So, a big reactor running for a year generates a waste form a little bigger than that.
It turns out to be about the same amount if you are running an IFR.
In the UK there is a vitrification plant in Summerfield,
do you happen to know whether it matches you high standards in your basement?
They are making a borosilicate glass out of the waste generated by a PUREX plant.
The facility itself - the melter would be essentially the same
except that you're feeding it rather than with boric acid and silica
you would be feeding it with phosphoric acid and iron oxide.
It is quite simple and straightforward.
Instead of recycling as they do - nitric acid,
we would be recycling hydrofluoric acid,
but it's pretty straightforward.
Thank you again Darryl. That was fantastic.