
Thorium - pkrein
http://rein.pk/thorium
======
allerratio
> but thorium reactors have been pretty experimental

Not all thorium reactors. A good example for an industrial grade thorium
reactor is the thtr-300 a high temperature thorium pebble bed reactor
(<http://en.wikipedia.org/wiki/THTR-300>)

> Thorium reactors are inherently stable, so “nuclear meltdowns” can’t happen.

This was also one reason for the design of the AVR in Jülich and it's
successor the THTR-300. Although there wasn't any "nuclear meltdown", there
were various other problems:

\- Small amounts of water leaking into the primary cooling circuit. Bigger
amounts could have lead to a buildup of hydrogen and oxygen which can cause
explosions. This is very comparable to a meltdown

\- The pebbles proved to be not very stable. This lead to a bigger amount of
radioactive matter being released into the surrounding environment by the
THTR-300

\- The AVR leaked a big amount of radioactive matter into the ground water

\- various other problems

Newer thorium reactor types won't have these problems because they will be
considered in their designs, but there's still the problem with the timeframe.
Estimates are that 2030 is the time when Gen IV reactors will get rolled out
(<http://en.wikipedia.org/wiki/Generation_IV_reactor>). Meanwhile Germany
replaced 3.5% of it's electric power sources from 2010 to 2011 with renewable
ones.

~~~
mtgx
I think Germany replaced a lot more than 3.5% with renewable energy.

[http://cleantechnica.com/2012/07/26/germany-26-of-
electricit...](http://cleantechnica.com/2012/07/26/germany-26-of-electricity-
from-renewable-energy-in-1st-half-of-2012/)

~~~
quote
One of you talks about absolute numbers, the other about % change. I don't
have any numbers easily at hand but you might both be correct.

------
fatbird
I've seen several thorium-boosting articles like this, and none of them say
why research and industrial development selected for uranium over thorium. Is
it just because the initial research into power came out of weapons research?

~~~
InclinedPlane
There are numerous different reasons. Thorium proponents often gloss over a
lot of the difficulties of the system, leading to a false sense of how easy it
would be to make such reactors. One of the biggest problems is that a Thorium
reactor is actually a U-233 reactor, which is bred from the Thorium, and U-233
is not so easy to work with. It emits a huge amount of gamma radiation, which
is highly penetrating and dangerous for human life.

To work with U-235 or Plutonium you only need a glove box, but to work with
U-233 you cannot have humans physically close to the material, you need waldos
and closed circuit cameras and so forth. This naturally increases the cost of
working with the fuel. But wait, it gets worse. As I said, gamma radiation is
highly penetrating and heavily ionizing, which means that it damages delicate
materials quite easily. Especially seals, made out of rubber or silicone or
what-have-you, and electronics. This makes fuel cycle handling hugely
challenging and also makes reactor construction rather challenging as well.

Now, likely we could overcome these problems but they are nevertheless huge
problems.

One of the big reasons why Uranium/Plutonium reactors have caught on is
because you can use 1950s technology to build reactors and process fuel.
That's not the case with Thorium/U-233.

~~~
ChuckMcM
This pretty much nails it, that is why things have to be very different with
Thorium and the combination "very different" and "nuclear" leads to an over
abundance of caution.

One of the reasons the travelling wave reactor is "interesting" is that starts
and ends with 'low grade' radioactive material, and works very much like a
'brushfire' which burns fuel ahead of it and leaves behind fully utilized
fuel. The downside is that it doesn't really "stop" in the sense that you
start one of these candles burning and for the most part it goes 10 years and
then sputters out, you can harvest the energy or not but you can't really turn
it off. (at least not in the early designs)

So much of the engineering issues with Thorium are mastering the fuel cycle
and that is something the US DoE hasn't spent a whole lot of time
investigating. Its an interesting question what we could do with a 1950's
attitude toward researching nuclear power uses and 2010's level of technology.

~~~
KitemanSA
LFTRs are not all that difficult. It is a WHOLE lot simpler than a Traveling
Wave reactor!

~~~
ChuckMcM
We have different definitions of "difficult" I suspect.

The Thorium fuel cycle produces U232, that stuff kills at a distance, through
walls. What that means is that there are a number of scenarios, one of which
Fukishima just went through, where the core gets uncovered and rather than
leaking Cesium it shoots gamma rays everywhere killing anything trying to get
near it. That is not the case with the U238 fuel cycle.

Not saying it can't be dealt with, just saying its different, and by being
different it is dangerous in different ways.

~~~
KitemanSA
"The Thorium fuel produces U232..." Yup, which is one of its nicest features.
It means that the U233 is unlikely to be used for weapons. And since it never
leaves the well shielded containment area in a LFTR, there is no hazard.

If the kettle is breached in the LFTR, the salt will probably just condense on
any small break and seal it. If the break is large, the salt drains into a
drain tank which is still in the shielded containment volume. No worries,
mate! Oh, and since there is no significant pressure and no volatile chemicals
like liquid sodium, there are no forces trying to disperse the materials.
Inherently MUCH safer than any PWR or LMFR.

------
stcredzero
Not only is thorium much more plentiful than Uranium, creating demand for
thorium also solves diffuses the Chinese economic control of rare earth
metals. Rare earths are plentiful in monazite sands as well as thorium and are
available in the US. Right now, thorium is a radioactive byproduct that
largely prevents economic extraction of rare earths. Build good thorium
reactors in the US, and both energy and rare earth situations are alleviated.

~~~
Tuna-Fish
The rare earth situation has already been solved. Mining has restarted in the
US and US will likely be self-sufficient in REE in 2 years.

~~~
alecdibble
Do you have any citations? I'm not trying to nitpick, I am just interested in
reading more.

~~~
troymc
I was also curious, so I did some digging and found this article:

[http://www.sfgate.com/opinion/article/U-S-rare-earth-mine-
re...](http://www.sfgate.com/opinion/article/U-S-rare-earth-mine-
revived-4057911.php)

------
JohnRandall
Here's an introductory video (10 mins)
<http://www.youtube.com/watch?v=N2vzotsvvkw> a longer video
<http://thoriumremix.com/2011/> (the surrounding links are worth exploring)
and a summary
[http://cybercemetery.unt.edu/archive/brc/20120621060336/http...](http://cybercemetery.unt.edu/archive/brc/20120621060336/http://www.brc.gov/sites/default/files/comments/attachments/flibe_energy_-
_lftr_thorium_top_ten.pdf) The important point to get is that the excitement
is not just "thorium" (as the title of the thread suggests) but the reactor as
well.

------
mtgx
This seems to be an update on the Norway story at the end:

[http://singularityhub.com/2012/12/11/norway-begins-four-
year...](http://singularityhub.com/2012/12/11/norway-begins-four-year-test-of-
thorium-nuclear-reactor/)

And how come he didn't even mention LFTR?

<http://en.wikipedia.org/wiki/Liquid_fluoride_thorium_reactor>

~~~
pkrein
LFTR are a type of molten salt reactor, which is mentioned, though certainly
not given enough attention in this first short article ;) will see what i can
do.

------
macrael
Are there serious arguments against Thorium? Or is it just early stage waiting
to be a bit more experimented with before going mainstream?

~~~
pkrein
yes. a recent nature article pointed out how thorium can be used to make
uranium-233 which can be used to make nuclear weapons.[1] (see the conclusions
section at the end of the article)

here's a more detailed explanation: the "old" idea before this nature article
was that the uranium-233 produced in thorium reactors would be inevitably
mixed with uranium-232 (which isn't useful for making bombs). but the nature
article pointed out that the real decay path is thorium-233 -->
protactinium-233 --> (uranium-232 AND uranium-233), and that by separating the
protactinium-233 from the thorium reactor's neutron flux after 1 month, you
can ensure that the protactinium-233 converts to uranium-233 instead of
uranium-232.[2] ... step 3 you can make a weapon.

[1]
[http://www.nature.com/nature/journal/v492/n7427/full/492031a...](http://www.nature.com/nature/journal/v492/n7427/full/492031a.html)
(sorry for the paywall :( ) [2]
<http://en.wikipedia.org/wiki/Thorium_fuel_cycle>

~~~
ScotterC
But this isn't practical in reality. First of all, you need a core of U-233 to
start the process but once you start you're adding thorium at different points
in time so the fuel slurry is going to be always a mix of thorium,
protactinium, u-232, u-233 and other various products which makes extracting
anything a royal pain. There's much easier ways of isolating weapons grade
uranium instead of trying to extract it from a ongoing fuel process.

~~~
slurgfest
The question isn't whether there are easier ways of producing, but whether the
thorium reactor doesn't provide better concealment for producing what would
bring unwanted attention when done in the 'easier' way.

~~~
stcredzero
If you're trying to conceal what you're doing, it would be best by far to
avoid U-232 being involved in the process.

------
troymc
Fun related trivia:

I just read Robert A. Heinlein's first "Heinlein juvenile" (i.e. young adult)
novel _Rocket Ship Galileo_. It was published in 1947. The rocket ship's power
plant was a nuclear reactor using... thorium.

~~~
pjscott
Probably not the best choice for fuel, though. It takes around a month after
capturing a neutron for thorium to become fissile, and if they just needed to
get to the moon and back, a thorium breeder reactor isn't going to be too
helpful with that. Highly enriched uranium is the way the NERVA guys went.

If they needed long-term power for a moon base, of course, it might be another
story.

~~~
cpeterso
Above [1], someone pointed out that a thorium reactor would produce gamma
radiation that is highly penetrating and heavily ionizing. Probably not the
"roommate" you want in the small confines of a spaceship. :)

[1] <https://news.ycombinator.com/item?id=4913976>

------
acd
Possibly Graphen coating of the metals could be used to solve the corrosion
problem in molten salt Thorium reactors.

If we solve the corrosion problem we get cheap abundant energy with little to
no nuclear waste and little to no material which can be used to make weapons
of mass destruction.

<http://www.gizmag.com/graphene-metal-corrosion/24434/>

~~~
KitemanSA
What corrosion issue? It has already been shown the a combination of adding
one additional alloying element to the Hastalloy N while keeping the salt
slightly fluorine poor will greatly reduce the already minimal corrosion
issue.

------
GiraffeNecktie
A pretty good article overall but he seems to go off the rails when he starts
talking about construction costs and assumes that a thorium reactor would cost
the same as a uranium reactor. My understanding is that a thorium reactor
should be dramatically cheaper for a variety of reasons (no need for a big
containment bubble for one thing).

~~~
aidenn0
That is currently all speculative. We don't know how much it would cost to
build a thorium reactor. There is strong evidence that it would be cheaper,
but has yet to be demonstrated. To quote the article:

"Safety features of nuclear plants seem to dominate the cost. There are many
claims about the inherent safety features of thorium Molten Salt Reactors. But
those claims have yet to be proven in working prototypes. If thorium reactor
designs and prototypes could prove the claims of inherent safety mechanisms,
then thorium could dramatically reduce the cost of nuclear power."

~~~
KitemanSA
Actually, there have been two working prototypes, one that ran without
significant issue for about five full power years.

~~~
KitemanSA
Oops, make that for two full power years over a period of five years. It was
after all an experiment.

------
KitemanSA
"Safety features of nuclear plants seem to dominate the cost. There are many
claims about the inherent safety features of thorium Molten Salt Reactors. But
those claims have yet to be proven in working prototypes." Actually, yes they
have. The three main safety features have all been demonstrated.

First, the working fluid is non-volatile, no pressure nor chemical reactivity
to drive dispersion of trapped gaseous fission products like Xenon and Iodine.
Those were the two significant dispersed radionuclides in Fukushima.

Second, those same kind of radionuclides are removed from the salt
continuously so there is not a store of them to BE dispersed.

Third, any loss of power to the reactor will passively result in a dump of the
salt into a non-reactive tank where it will be passively cooled. It will be
"walk away safe"!

------
peasoup
This Nature article throws some cold water on the claims that thorium isn't
very useful for making weapons.

[http://www.nature.com/nature/journal/v492/n7427/full/492031a...](http://www.nature.com/nature/journal/v492/n7427/full/492031a.html)

Unfortunately the article is paywalled.

~~~
adam-f
U233 more readily fizzes than booms, since it fissions faster it tends to pre-
explode before getting into a really good super critcal state (probably
something to do with the .6 instead of 1.6 delayed neutrons per 100 fissions
mentioned above, it also has a slightly better neutron production factor than
u-235).

U233 will have U232, which decays through some very high energy gamma
emitters, making U233 impossible to smuggle through shipping ports etc...
These gamma emissions also kill humans in minutes, so would-be bomb makers
would need to use robots or other remote handling techniques to fabricate a
bomb. This is something a rouge state would have a hard time pulling off, and
is practically out of reach of basic terrorists.

It's not impossible but it would be easier/cheaper to just mine/steal some
natural uranium and build centrifuges. It's easy to make U233 from thorium and
thorium is abundant, so, really, how would reactors make thorium/U233 more
available to rouge states when they could basically make it themselves, and
why would they choose the U233 route?

------
CurtMonash
I took a nuclear engineering class in 1975. In essence we discussed three
reactor design ideas:

1\. Water, pressurized or otherwise. 2\. Gas-cooled. 3\. Molten-salt.

The big problem with molten salt was that you sent it through a whole lot of
pipes. Hence, the physical plant that would get radioactive was much bigger
than just the core of a water-based reactor. Also, you just had to deal with a
whole lot of radioactive sludge.

A huge advantage was that the thing couldn't lose coolant and melt down; a
catastrophic failure would amount to the molten salt sinking into the earth
below.

It seemed at the time that if any major change would be made, it would be to
HTGRs -- high-temperature gas reactors. But it also seemed as if the true
"best" idea was molten-salt.

------
sneak
Note well that you are reading an article by someone who doesn't know the
difference between fission and fusion (he says that a uranium fission reaction
can result in a "thermonuclear explosion").

~~~
pkrein
mmmm, yes quite inaccurate on my part. apologies. of course... uranium fission
was a critical part of the hydrogen bomb ;) will correct that thanks.

------
JohnRandall
Here's a full, frank discussion of the use of thorium in a LFTR
[http://www.peakprosperity.com/podcast/79398/kirk-sorensen-
de...](http://www.peakprosperity.com/podcast/79398/kirk-sorensen-detailed-
exploration-thoriums-potential-energy-source) The nice thing about this item
is that there's a transcript. For example, "Why thorium, not uranium?" Well
the technicalities are explained (thermal vs fast reactors).

------
nwh
I'd be much more comfortble seeing resources going to improving solar and wind
power. Storage of waste is always going to cause massive issues.

~~~
stcredzero
Thorium reactors can burn our current nuclear waste store, reducing its volume
by an order of magnitude and the duration of dangerous radioactivity to under
300 years.

~~~
DasIch
300 years is still far too long. You simply cannot expect most organizations
to survive that long and remain trustworthy. Apart from that the real costs
would still be very high.

~~~
DennisP
The point is, we have a lot of nuclear waste _right now_ that needs
containment for 10,000 years. Put it through liquid thorium reactors (or
integral fast reactors) and you reduce the amount of waste by a couple orders
of magnitude, while reducing the timeframe to 300 years. Do you have a better
plan for it?

~~~
danielweber
France seems to do okay by recycling it.

Of course it's cheaper to just toss the old stuff somewhere and dig up fresh
uranium.

------
slacka
If you want to help raise public awareness of this issue, sign the petition on
the We-The-People website to preserve U233 used to make LFTR reactors.
<http://wh.gov/5Rmc>

More info can be found here <http://thoriumpetition.com/>

------
joss82
Could someone please open a kickstarter for a new thorium reactor design and
construction?

I'll gladly contribute to the initial cost (probably billions) just to get a
lifetime of free and CO2-efficient electricity.

Couldn't this way of funding bypass most "big firm" inefficiencies and legacy
cruft, just as SpaceX did?

~~~
andrewjmcd
There's a non-profit to support development of LFTR here:
<https://www.facebook.com/EnergyFromThorium?ref=nf>

If you are an American, another thing you can do is sign the petition to stop
the destruction of the U233.

<http://wh.gov/5Rmc>

------
Kronopath
For those interested, here's a TEDx talk about liquid fluoride thorium
reactors and how they could be used to power a moon colony:

<http://www.youtube.com/watch?v=N2vzotsvvkw>

------
tripzilch
Shouldn't one rather frame this debate not as "proponents vs opponents" but as
"scientists trying to figure out what is actually the case and hopefully
inventing better nuclear power in the process"?

------
Permit
Does anyone know how much less waste Thorium produces when used compared to
Uranium? Both this article and Peter Thiel's linked article say "less", but
neither are exact.

~~~
pkrein
It's actually a bit hard to quantify. The true cost of radioactive waste is
related to what type of radiation it emits (gamma? alpha particles?), how
long-lived the radiation is i.e. it's half-life, and the actual quantity of
that material that is produced per Watt. This triple-axis makes it a bit hard
to quantify in simple terms, but the main idea behind thorium is that the
waste has a significantly shorter half-life[1]. Depending on the exact reactor
design, there may also be ways to reduce the quantity of secondary waste (like
water that's been exposed to heavy neutron flux while transferring energy from
nuclear core --> steam turbines).

[1] : [http://www.forbes.com/sites/williampentland/2011/09/11/is-
th...](http://www.forbes.com/sites/williampentland/2011/09/11/is-thorium-the-
biggest-energy-breakthrough-since-fire-possibly/)

~~~
g8oz
Offtopic: how did you get a .pk domain?

~~~
umairsiddique
<http://www.pknic.net.pk>

