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It has occurred to me that there is a potential problem
with respect to "nuclear proliferation". I am pointing it
so that steps might be taken to try to prevent that
problem from becoming real.
It is well known that if you take an atom of Uranium-238
and add a neutron to it, it becomes
of radioactive decay, becomes Neptunium-239 and then
Plutonium-239 (all within a few days). It is not hugely
difficult to make a nuclear explosive device from some
(classified quantity of) Pu-239 --every nation that has
appears to have succeeded on the first attempt-- and so
the international community tries to thoroughly control
various ways in which uranium gets used.
Meanwhile, some other chemical elements don't appear
have much in the way of "international controls", and the
two elements I wish to bring to your attention are
Almost all naturally-existing Thorium is Th-232 (and it is
3 times as abundant as Uranium), and more
than 90% of Lithium is Li-7 (often the percentage is even
higher, because lots of lithium has been processed to
remove the other isotope, Li-6, for making hydrogen
Well, today I happened to notice that someone could
Li-7 and put it into a modest particle accelerator
enough that just about any mad scientist could afford
one), and then bombard Th-232 with it and ....
Well, the exact reaction is Th-232 + Li-7 -> Np-239,
quickly becomes Pu-239....
Admittedly, it would take someone quite a while to
bombard enough Thorium to end up with enough
to build an explosive nuclear device, which gives us a
window of opportunity to see about enacting
controls to prevent some mad scientist from getting
||aren't people actually trying to create commercial
small scale Thorium reactors, even car engines?
||I'm pretty confident all/most of these pathways are well trodden.
||Li7, since the Castle Bravo incident, has been known to be similarly useful as a nuclear fuel as Li6. Whoops. That's an interesting story if you're interested - 15Mt yield, when predicted yield was 6Mt. Someone either got fired, or promoted over that one (but in reality, there were some horrible consequences).
||What you might not have realised is there is a fissile fuel available as a direct product of Thorium neutron capture, that is U-233. In fact, in a reactor, it is the U-233 that is actually fissioning to produce energy, the Thorium is only the feedstock. The Americans, and some other nations ran the requisite trials of U-233 as a bomb making material many moons ago. It isn't as suitable as U-235 or Pu-239, but it does work.
....So, there is already a big proliferation risk with Thorium reactors, and you don't need a particle accelerator either...
||There are many benefits as well, but Thorium reactors are, by definition, breeder reactors of fissile fuel. Some long and hard consideration needs to be given to the potential consequences of broad utilisation of Thorium based nuclear power.
||While superficially attractive, the idea is
unworkable. What is being described is
||Bombarding nucleii with other nucleii with
the intent of getting them to fuse is radically
different from neutron bombardment.
Neutrons don't interact, and the process is
dependant only on the cross-section of the
target nucleii and the energy of the neutrons.
||In the process described, the Lithium nucleii
will just ionize the target, rapidly shedding
energy- unless the target is plasma. That's
one of the reasons why fusion systems, both
weapons and reactors, require plasma.
||Say you get a lucky hit, and make an atom of
Pu. What's to stop it being hit again, and
transitioning into something else ?
||The U -> Np -> Pu production cycle works
because a reactor can produce and sustain a
huge flux of surplus neutrons. In the
Manhattan project, nanogramme quantities
of Pu were produced using cyclotrons to
allow evaluation of the chemistry. It was
extremely slow and energetically inefficient.
||This is not something anyone should lose
||U233 isn't brilliant as a fissile material. But a
Thorium reactor does produce that highly
desireable neutron flux. Pop a few slugs of
natrural Uranium metal in your Thorium
powerplant and let them cook, then drag
them out and separate the Pu. Et Viola
||Yes. A much higher risk is someone operating some sort of brumbied-up breeder reactor producing large ammounts of raioactivated materials and putting them in dirty bombs. Ultimately, that wouldn't even be very hard to do, certainly not requiring of a complex industrial power generating plant or similar infrastructure. I'm talking something more like an underground pit with minimal automation/instrumentation, some sort of moderation and scramming system (literally, pumped water, and a pile or boron salts), a nice hot neutron source to get things started, and a lot of free time.
||That's what I would be worried about. I wonder if any nefarious groups have seriously considered this, and/or started?
||I'm completely aware of ALL the usual nuclear-
reaction cycles for energy production. And I'm
also aware that the reaction described in the main
text here is an energy-consumer, not an energy-
producer. The present HalfBakery category,
however, doesn't specifically require that energy
be produced; any sort of nuclear-related energy
Idea should qualify for inclusion.
||(But didn't I write enough to make it obvious that
AFTER one makes a lot
of Plutonium from Thorium and Lithium, a quite-
large quantity of energy can be released,
||And so this Idea said nothing about energy
production from the specified reaction; it is
merely a Warning about the
potential major mis-use of certain substances, of
which Lithium is most certainly readily available,
and Thorium, so far as I know, is also more-
available to average folks than perhaps it should
||Our criticism is not based on the energy
efficiency aspect, but rather on the extreme
difficult of getting it to work at all in the first
||// I wonder if any nefarious groups have
seriously considered this, and/or started? //
||Well, the Nazis did this in the 1940's and they
are close to the gold standard for out-and-out
nefariousness (the actual gold standard being,
of course, the french. As usual).
||For another and rather different Plutonium
Production Pathway, start with Bismuth. 100% of
natural Bismuth is Bi-209, and it is easily available
(see ingedients of "Pepto-Bismol").
||Now look at Silicon. About 25% of the Earth's crust
(the average rock) is Silicon, and about 3% of
Silicon is Si-30. If you extracted that and used an
appropriate accelerator to jam a Silicon-30 nucleus
into a Bismuth nucleus, the result is Berkelium-
239, which decays to Curium-239, which decays to
Americium-239, which decays to (ta-dah!)
||//About 25% of the Earth's crust (the average rock) is Silicon,
||Weird, about the same amount in glamour models, it's just a coincidence, isn't it?
||[not morrison rm], there is a difference between
"silicon" and "silicone". The former is what I was
referencing; the latter is used in the plastic surgery
industry (and others).
||Stranger, there might be 25% silicon in the silicone.