
Thorium backed as a 'future fuel' - ximeng
http://www.bbc.co.uk/news/science-environment-24638816
======
apendleton
As has been typical over the last year or so of writing about thorium power in
the press, this article glosses over the difference between using thorium in a
conventional water-cooled reactor and using thorium in a liquid fuel
configuration, which is what lots of thorium advocates want. Many of the
benefits (particularly in terms of increased fuel burn, and automatic shutoff
in the event of failure) are dependent on the LFTR design, but one could
easily read this article and assume they also apply to the MOX design being
developed in India; for the most part, they don't. Certainly, you get _some_
of the benefits of thorium fuel in that configuration (more abundant fuel as
compared to uranium, for example), but it's an important distinction that
needs to be part of the conversation.

~~~
jjoonathan
The Thorium publicity spree is about rebranding nuclear power, not about
having a technical discussion. If the only message that gets across is "new
thorium reactors are safer than old reactors," it's still a win for everyone
involved because this message is a subset of the truth (new reactor designs
are safer than old designs in general).

I don't think the public properly appreciates the extent to which nuclear
safety mechanisms have improved dramatically over time, not least because a
design's safety profile is largely "frozen in" when it is built, so we
occasionally see a half-century old "bug" rear its head (Fukushima). The
public sees it as evidence against the safety claims of future nuclear plants,
even though it is not (quite the opposite: building newer, safer plants lets
us retire the old, dangerous ones). Rebranding might get them to take another
look.

Actually, I think including as much detail as the parent post did might be a
net negative because it muddies the core message. Simplicity and
straightforwardness are key.

~~~
mcv
One big thing that always gets mentioned in any Thorium discussion is that
originally, Uranium was chosen over Thorium exactly because it is inherently
less safe; it can be used to make bombs, which is what all the nuclear powers
were really interested in. So Uranium research got lots of government support
while Thorium research was dropped.

I'm no nuclear physicist, so I have no idea if Thorium really is inherently
safer than Uranium, but if it is, I'm all for it. But if it is indeed safer
and cheaper, and old tech that's been ignored for decades, then why aren't
there new Thorium reactors popping up all over the place? Or are there? Is
anyone still investing in the Uranium/Plutonium cycle?

------
hygap
As far as I was aware the reactors at Fukushima shut down correctly as soon as
the earth quake occurred. While the crisis definitely continued I think the
reporters portrayal of the reasoning is somewhat misleading. As it insinuates
it was the fuel rods inability to control the reaction was the problem, rather
than the cooling system's inability to deal with the excess heat generated
post shut down.

"When a uranium reactor overheats and the fuel rods can’t contain the chain
reaction, as happened at Fukushima, the crisis continues."

~~~
mnw21cam
Yes, the reactor shut down correctly. However, in a working uranium reactor,
there will be large quantities of fission products that are also radioactive
and are therefore spontaneously decaying in a long chain towards stable
isotopes. Some of the fission products are quite short-lived, so for quite
some time after the reactor is shut down they will be generating a lot of
heat.

What happened at Fukushima is that the cooling system that needs to keep
running for weeks after a shutdown broke. This caused the water in the
reaction vessel to boil, uncovering the tops of the fuel rods, which then got
so hot that they broke steam into constituent hydrogen and oxygen (which
caused the subsequent explosions) and they cracked open, releasing some nasty
isotopes into the coolant water. The coolant water with nasties in is what has
been leaking out into the environment.

~~~
hygap
I agree, well expanded. The mechanism seems to be a lot safer in a liquid
thorium reactor where the thorium drains away into a safety chamber in the
event of a similar disaster.

I just wanted to point out the events the article portrays are incorrect and
the writer could have conveyed this message without insinuating there was a
meltdown due to the failure of the (wait he says fuel rods not control
rods....) O well.

~~~
mnw21cam
Another advantage with a liquid fuel is that you can do a continuous
reprocessing cycle (pump the fuel through a chemical plant) to remove nasties
from the system. With solid fuel pellets all you can do is hope that the
pellet doesn't crack and let the nasties out. Having no pressure vessel with
ultra-superheated water and a 1000-times-the-size containment building around
it in case it all suddenly turns into steam helps too.

------
wil421
Key words: "I’m a lawyer not a scientist but in my opinion..."

Sounds like he's not a lawyer but a politician.

~~~
arethuza
"the former Swedish foreign minister" \- right before the bit you quoted.

~~~
wil421
My point was I dont want to listen to a lawyer or politician. Give me the
words of a scientist, preferably a nuclear one.

~~~
vidarh
He's a lawyer and politicians whose job for many years was to reconcile the
views of scientists and politicians with respect to nuclear. And in this case
the political impacts of Thorium are just as important as the science, and
likely the reason they asked him questions:

Because it is far harder to use it to create nuclear weapons, there are far
fewer political hindrances to mining and trade in Thorium, as well as
political concerns over letting potential enemies establish Thorium reactors.

The supplies are also larger, and well distributed, which is also politically
beneficial.

Nuclear power is not all about the science.

~~~
nagrom
And because Thorium cannot easily be made into weapons, the military will not
fund development of the use of it as a fuel - nor will it expend the political
will to make the construction of a thorium-reactor possible. And so we keep
using Uranium. The political hindrances of using Thorium turn out to be much
greater than the political hindrances of using Uranium.

~~~
stonemetal
The military uses nuclear power outside of weapons, especially in the navy.
Subs, aircraft carriers and the like are all nuclear powered, so they have an
interest in safer nuclear power as well.

~~~
angersock
Yeah, people seem to forget that the largest operator of nuclear reactors is,
if I recall correctly, the US Navy.

------
gngeal
A Swedish guy rooting for thorium? Odin's beard, how surprising!

(Jokes aside, I've been in love with this idea since my high school studies of
nuclear engineering. I know a lot of these things didn't pan out eventually,
but I still find that sad.)

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swashboon
Does anyone know if any substantial gains have been made in what I believe is
the number one problem with Thorium reactors: that moving liquid salt through
the reactor is extreamly corrosive and parts don't last very long (under a
year iirc)?

~~~
DennisP
Oak Ridge was actually pretty successful with Hastelloy-N, which pretty much
solved the chemical corrosion issue in the absence of neutrons. There was
still some concern about the neutrons causing problems, but Oak Ridge thought
they'd figured out how to solve it by adding something extra to the alloy. It
hasn't been tested long-term though.

~~~
not_that_noob
See below. It was tested for 9 years and didn't show significant corrosion.
The leak happened not in the Hastelloy but in a ceramic seal between the alloy
components. An appropriate seal or coating on the seal may be able to fix this
issue. Overall, I'd say the containment issue is as you say mostly solved.

Here's the
report:[http://moltensalt.org/references/static/downloads/pdf/ORNL-T...](http://moltensalt.org/references/static/downloads/pdf/ORNL-
TM-4189.pdf)

~~~
swashboon
Great to hear, thanks.

------
known
The ratio of plutonium needed to seed and convert thorium into fissionable
uranium-233 is very high (4:5)

~~~
DennisP
But you only need it to start the reactor.

