[ExI] cost of SBSP and thorium

[John Clark]

On Mon, Aug 20, 2012 at 6:38 AM, Charlie Stross <charlie.stross at gmail.com>wrote:

> Trouble is, any Pu-240 in the mix will decay via gamma emission and mess
> with the explosives in the surrounding implosion system


But there is always a layer of Lithium Deuteride and more important a thick
U238 tamper between the Plutonium 239  tainted with Pu-240 and the chemical
explosives, and that shields against most of the gamma rays; good thing too
otherwise nuclear warheads would be lethal to the crew in submarines.

> and then there's the 12.3 year half life of the tritium used as a neutron
> emitter and a booster in suspended-core warheads.
>

Modern H-bombs may use a very small about of tritium in their neutron
initiators but the vast majority is bred in a very small fraction of a
second from Lithium Deuteride. It was originally thought that only the rare
isotope Lithium-6 would work for this purpose but it was later found that
the common isotope Lithium-7 would work almost as well. That's why the
first H-bomb test that used Lithium Deuteride, the Castle Bravo test in
1954, was expected to produce a blast of 4 megatons but ended up producing
15, it killed several Japanese fishermen who were well outside the official
danger area.

  John K Clark
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