Iím Rusty Holden Iím from Thorenco and talking about the little LFTR, a pilot plant that
I designed computationally in the last couple of months.
In overview on where we go next because we have to do a little materials testing.
This is 40 Megawatts, hereís our defining differences, the neutrons converting Thorium
directly to Uranium-233.
Also in the pure design, which I have here, weíre not producing any Plutonium to speak
of or any of the other dreaded transuranics.
The usual suspects, thee contamination issue for thousands of years.
With the liquid the defining difference: no melt down, no fuel rods, no cooling ponds
and again no 10,000 year fuel storage problems.
Finally with the liquid fuels we have the safety situation pretty much in hand.
Youíve seen the fuel dump that has been discussed, this is when the hot fuel drops down into
the tank during the unforeseeable emergency situation.
My only improvement on that is to salt the tank that receives the hot fuel with denaturing
materials and with diluents and with neutron absorbers but weíll get to that in a moment.
Here we go, how do we start this thing?
I pick a molten salt Sodium Beryllium Fluoride, Iím using this one because its inexpensive,
readily available and you donít have to do any isotopic separation.
Isnít a case of Lithium, you have to fish out the Lithium-6 in this you donít.
There is a penalty, thereís a little bit of neutron cost in the economy here but I
think this is a good salt to look at, itís excellent because its got a very long liquid
range; 350o C - 1500o C thatís good.
It gives an operating range between 450 and 650, which is good it doesnít strain the
materials.
The nice thing also is this, a low power design, I wanna test the materials, I wanna do it
inexpensively so we got natural convection that we can do with a pool type reactor design.
Whatís our fuel?
This is easy, all we do is we get our coolant our Sodium Beryllium Fluoride and we add our
Fissile to it in this case its pure 235UF4, We add our Fertile which is our Thorium Tetrafluoride
and I examined some cases just varying the amount of Thorium in the fuel.
The good news is this, the more Thorium the better the fuel.
Hereís the liquid fuel characteristics melted around 400o C.
We can adjust that melting temperature by adding additional Fluoride salts so we can
have a lower melt.
We can do that also with the coolant, we can adjust the melting temperature with relative
Eís.
The fuel is compatible with the coolant because itís made out of the coolant and its compatible
with the Hastelloy-Nickel Cladding.
The materials absolutely necessary to separate your coolant from your fuel, you donít wanna
contaminate your coolant because then if you have that possibility your not gonna be in
business ever.
In this reactor design I use the Beryllium in the salt as the moderator, so I sidestep
having moderator in the molten salt assembly, I donít have graphite sitting in the cord,
makes a smaller design.
This is the conceptual honey comb geometry, this is new geometry, thee honey is the yellow
thatís the coolant coming your way.
The blue is the Thorium thatís your neutron reflector your blanket, its kicking those
neutrons back into the core and the red is the fuel circulating in the Hastelloy Lapis.
In this chart weíll say weíre pumping the fuel north and then the honey comb weíre
looking down on the reactor and the honeyís coming our way, thatís our ??.
The reason we have this geometry is with the thermal management, Hastelloy does not conduct
heat as well as many of the other more traditional materials do so I Increase the surface area
of our cladding so that we achieve a nice result.
We have the fuel pumped throughout the Lattice.
Also with this Lattice design we have a cover gas in our fuel and weíre pumping that cover
gas around and this is the way we fish out our fission gases.
Your fission gases are sort of the parents of many of the fission products and this is
a superior way to clean and condition your fuel during operations is to manage that gas
and the easiest way to do it, is to circulate a cover gas sitting on top.
Hereís thee computational innovation here which shows you in to detail what the hexcel
system looks like.
With the green is the fuel weíre pumping at north again, the honey the yellow weíre
coming your way, thatís the coolant and your fuel and the Hastelloy is the magenta its
your cladding thatís separating fuel from coolant.
We see what the core looks like, weíre at 160cm across thee hexagonal shape, itís a
right hexagonal prism, so its 160cm tall and 160cm across the shoulders.
Thee opening of the lades are in 4cm segments.
Theyíre there because thatís the mean free path of the neutrons in this particular assembly.
We put my hex system where it saids reactor core, it heats up that chimney full of salt,
salt goes up to the top visits the heat exchanger gets cool goes back down thatís your primary
loop, your salt is in an endless circle here
and inside of this flask I call it a thermal reservoir.
We have a lot of heat that we store and the way that we fish it out is with the heat exchangers
and the secondary loop probably critical CO2 ?? heat exchange whatever the most efficient
is.
I like the gas because your hardwareís a lot smaller and a lot more efficient.
I keep my traditional control rods and safety rods that sort of thing.
I keep it there for regulatory reasons, its good to have traditional controls in addition
to all the other controls weíve designed that are new.
But this provides a nice transition from the old to the new, is using the trident to control
it gives us a good shot of having regulatory success.
This is what the neutrons look like in the fuel.
Horizontal scales, increasing energy goes up to 10 million electronic vaults.
Way down in this end, a tenth or so of electron vaults, tiny electron vaults.
The green shows you Thoriumís appetite or affinity for neutrons as a function of energy
and the red shows you affinity by Uraninum-233 in this case for neutrons.
You see Uranium loves those cold or those chilled out or thermal neutrons and a little
bit below one electron vault.
The idea of this thing, what makes it go is you have to have enough thermalised neutrons
to keep that neutron chain reaction going.
But also you wanna be able to make as much fuel as you can on the go, so thatís why
I like a little higher spectrum here or this is pretty hard spectrum and whatís going
on is weíre getting lots of opportunity for the neutrons to be captured by the Thorium.
so that we can almost, we can get towards a break-even situation of producing as much
fissile material as we consume during reactor operations.
Thereís many advantages of course, thereís great making the fissile right in the core
because thatís the safest place in the world for fissile because itís protected by radiation
shield.
What happened with these three fuel designs, the 1 on this is when your reactor is critical,
when you go below 1 that means your reactor is fizzled out, the fission products have
won the battle and now youíve just got a bunch of hampers.
The more Thorium thatís in the fuel thee longer itís gonna last, the longer its gonna
stay above 1.
These computations were done without pulling the fission gases out.
My next set of computations will be using condition fuel to flatten out this chart so
that my fuel will be very very long lived, many decades probably of fuel.
The idea of this is to keep the fuel in the plant, not take it away from the plant, regulators
like that itís a good idea.
The way to do that is condition that fuel, you can, Iíve talked about the fission gases
you capture them outside the core
the trick is you just pull them out run them through a cold box and your fission gases
will get stuck in the cold, theyíll come out and then theyíll drop down into the fission
products solids that are thee neutron poisons.
This was our performance the low power test, 10 megawatts, we burned up 141 Kg of U-233
in this exercise then we produced about 102 kilograms of U-233.
With a big fissile load of this thing at 1.6 metric tonnes thatís high but thatís the
price of having a fuel that can be made eternal.
Being able to work in the harder spectrum rather than a softer thermalised spectrum.
We have 9 tonnes of Thorium in here and we produced 23 grams of U-232 thatís the stuff
that shows to the world, it sends out a gamma signal, you can see it from a satellite, way
out in space or instruments on a boat or on the ground
It saids thereís Uranium-233 here its hot, if youíve tried to run off with it, itís
a dead giveaway and if youíve tried to build a bomb out of it, it provides a nice way to
come in with some counter measure that see those photons and will zoom right in and zap
wherever that unaccounted for Uranium is.
Hereís are transuranics, transuranics are usual suspects, Plutonium-239 and hangs out
for 24,110 year and a half-life, takes a quite a long time to fizzle out.
These figures show ten to the minus 7, ten to the minus 4, ten to the minus 7, ten to
the minus 9 grams, this is tiny, tiny production.
I got lazy when I did the edition here I said less than a milligram, well its significantly
less than a milligram a thousand of a gram of these dreaded materials 10 years of operation
under case 6.
This is good, waste profile much healthier all we have to worry about is the fission
products and weíve already captured a lot of those fission products in that cold box
and we have a much more workable situation here.
Now hereís the fuel dump the vertical pipes that connects the hex-cell array to thee safety
drums.
These are the emergency drums, we canít foresee every kind of black swan when its gonna show
up, when its gonna show up and what itís gonna be.
So under this system we can trip the emergency switch either by the operator if heís still
there or a seismic signal comes through or a thermal signal comes through in other words
the fuels too hot.
So it can melt through a plug or the other methods as the temperature of the fuel increases
curie points of magnetic materials can be exceeded and circuits opened and physical
circuits opened so we can dumb that fuel right down into the tank and there is the denaturant
Uranium-238 sitting right in the tank in gravel form it melts into the fuel denaturing it.
We have Cadmium Fluoride in the gravel in the tank its there grabbing the excess thermal
neutrons taking them out of circulation.
We also have additional dilutants in the tank we can use the coolant or there are some other
dilutants that are low melting fluoride compounds that can solve the after heat problem immediately
because weíre changing the density of the fuel
or the density of the fission products, weíre making them more aware in the material so
we can handle this thing with passive air coolant.
It just like a bunch of drums sitting in the air as long as the air can circulate thereís
enough cooling so that we donít have a problem controlling that after heat as weíve seen
in Japan and elsewhere.
Hereís our ?? a little bit our prism is 5ft 2 thatís what a 160cm, so 5ft 2 tall, 5 ft
2 wide.
Our fuel volume is 615 gallons we all understand gallons the leader always ?? me but thatís
all there is 615.
Weíve got a lot of coolant in this design of mine because what weíre trying to do is
my that thermal reservoir because then you get load following effects, sort of money
in the bank with a big hot thermal full of salt, 93,000 Litres thatís about 25,000 gallons
of hot salt.
and then our reflectors of Thorium in this case it was solid I got 16 tonnes of reflector
there, thee reflector salt had also with a little bit of Uranium-238 so that thee Uranium-233
could produce in the reflectors denature.
The advantage of remote fuel handing this for the people the plant workers they donít
have to be exposed to the fuel the way plant workers are today with the fuel.
We can pump it around capture those fission gases during operations remotely.
We have the emergency situation of lets get that fuel cocooned there it is again it drops
into the drums we got the dilutant, denaturant and we got our neutron absorbing materials
and gamma shielding right in the drums and ready to go weíre prepared for an emergency.
The proliferation hardening on this one that U-232 sends out that signal, so if somebodys
tried to run off with it we can catch them pretty easily.
Weíve got Protactinium in the fuel this is the intermediate between Thorium and Uranium-233,
it sends out a bright gamma cascade, it provides a very strong radiation shield.
Itís got a one month half-life so thereís about a 3 month period where that fuel is
gamma hot.
In addition there will be some other fission products in that fuel and it will also be
adding to thee radiation shield.
So if you canít safeguard your fuel in 3 months your not running a good country put
it that way.
For the proliferation community the guys that are always worried about people running off
with the fuel if thereís a problem weíve denatured it, the fuel cannot be weaponised.
So hereís the trick is as long as we donít have Uranium-238 in the fuel during operations
weíre avoiding making the Plutonium and transuranics which is good that being a good ??.
But to manage the other side the dark side the guys who wanna make weapons and stuff
then we got to contaminate the fuel.
My argument is lets contaminate it only in emergency situations when we have to and that
provides a much better environmental footprint for this type of nuclear fuel.
Also we have active control features in this thing, I pointed out we have control rods
and that sort of thing this makes it easier on the regulatory community.
They see something familiar, codes exist to manage the regulatory side of things the controlling
of this thing using standard neutron absorbers in the reactor ??
Again the fuel quality is managed conditioned during operations so we can add that fissile,
we can remove the fissile we can also add and remove the fertool.
The nice thing is we can get those fission gases and capture them and keep those fission
products out of our fuel.
Hereís the thank you notes this goes to my friend Rick Witt an ?? at PPNL whoís done
computational work for me for about 6 years now we got a pretty, well figured out how
to optimise these things.
Doctor Burchfield did the review for this speech to make sure I didnít misstate anything.
The department of energy and PNNL provided the funding for the programme.
I thank the Alliance for the podium today and thereís just one more thing Thorium developers
remember weíre in a regulated area here ok because we make Uranium-233, any Thorium developer
in the room make a note talk to your lawyer about 10 C.F.R.810
Weíve got export controls and so forth that come from the Proliferation Trees and other
international instruments.
All you have to do is get permission, to do what youíre planning to do and you have to
disclose who youíre working with.
But if you donít do if you try to you know do it circumvent it, you might get on the
wrong side of the law and who wants that, I mean the penalties 10 years to life lets
pay attention to that.
Thank you very much Iím Rusty Holden and its time for the next speech.
Thank you Rusty.