[ExI] Silence in the sky-but why?

John Clark johnkclark at gmail.com
Wed Sep 25 16:27:30 UTC 2013

On Tue, Sep 24, 2013 at 4:15 PM, Kelly Anderson <kellycoinguy at gmail.com>wrote:

> I recently spoke with a group of retired engineers who used to work for
> theIdaho National Laboratory. They indicated that they had once built and
> detonated a thorium based nuclear weapon, which I thought was interesting.
> Most of the thorium advocates claim it is safer in terms of nuclear weapons
> proliferation. Perhaps it is really difficult to make a bomb out of
> thorium, but apparently, it is possible.

Nobody can make a bomb out of Thorium but you can turn Thorium into Uranium
233 and you can make a bomb out of that, but as far as I know it has only
been attempted twice. in 1955 the USA set off a plutonium-U233 composite
bomb, it was expected to produce 33 kilotons but only managed 22; and in
1998 India tried it but it was a complete flop, it produced a miniscule
explosion of only 200 tons.

Today no nation has U233 bombs in their stockpile and there is a reason for
that. The critical mass for U233 is 16 kilograms, that is slightly smaller
than the critical mass for U235, but for P239 its only 4.4 kilograms. And
U233, if it were obtained from a Thorium reactor like a LFTR, would be a
nightmare to work with because about 1% of it would be contaminated with
U232; in one second your unexploded fission core would produce more gamma
rays than a plutonium core would in 26 hours. All those gamma rays would
play hell with the bomb's electronics and decompose its chemical explosive,
not to mention causing a bit of bother to the poor terrorists rushing
around to finish building the damn thing before they dropped dead. And
forget about trying to hide this behemoth, all those gamma rays are like a
huge neon sign saying "NUCLEAR BOMB HERE".

Existing Uranium reactors have produced about 1600 tons of Plutonium, there
is no way to avoid them making the crap and regular reactors don't burn it
up so it just accumulates. A LFTR produces U233 from Thorium but it burns
100% of it up, it has to or the reactor won't operate, and it makes
virtually no Plutonium. The U233 is completely burned up inside the reactor
where its hard to steal, and if it is stolen the theft is obvious because
the reactor stops. A Uranium reactor produces lots of neutrons but a LFTR
makes less of them, so it needs all the U233 that it makes
to keep the chain reaction going, if you try stealing some the reactor will
simply stop operating making the theft obvious.

And in existing Uranium reactors used fuel rods are shipped to
reprocessing  plants to extract the Plutonium. In one case the potential
bomb making material needs to be shipped across the country, with a LFTR it
never leaves the reactor building.

So you can make a bomb out of U233 but its hard as hell, so with thousands
of tons of easy to use Plutonium already produced and more made every day
in conventional reactors, not to mention thousands of poorly guarded fully
functional bombs in the former USSR, why would any self respecting
terrorist bother with U233, especially when it's so hard to steal from a

  John K Clark
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