A huge expansion of nuclear power has been proposed as for a solution
to the combined peak oil and global warming problems.  

There is an unrecognized problem with nuclear power.  It is believed
that the reason the North Korean bomb fizzled is that they used
reactor plutonium, which has a high percentage of plutonium 240.
Plutonium 240 has a high rate of spontaneous fission.  That causes the
bomb to go off in a low-grade mode before the core is completely
compressed.  

Weapons grade plutonium is 90% or better plutonium 239.  It is made by
pushing slugs of uranium though a reactor fast enough that little of
the plutonium 239 formed picks up a second neutron and becomes
plutonium 240.  The slugs are then chemically separated to recover the
plutonium.  It's a trade off between grade and production rate.

http://en.wikipedia.org/wiki/Plutonium_239

Several years ago it occurred to me that exceptionally high grade
plutonium 239 could be made by briefly exposing U 238 in solution to
neutrons, removing the plutonium with from the solution with ion
exchange and pumping the solution back though the reactor to convert
more U 238 to plutonium 239.  (U 238, depleted uranium, is scattered
all over Iraq.)  

This will generate low cost plutonium 239 upwards of 99% purity,
perhaps high enough that simple gun type bomb designs could be used.
Considering that over a fuel consumption cycle a large power reactor
generates a number of kilograms of neutrons, tapping 10% percent of
them in this loop would produce a considerable amount of super weapons
grade plutonium.

For a long time I considered it something I wished I had never thought
of.  But while I was in jail recently and thinking there was a good
chance the cult would kill me, I decided to release it.  (Mentioned it
here a few weeks ago.)  After all if I can think of it, so can any
number of other people.  Released it will give International nuclear
inspectors an idea of what to look for.

I spent considerable thought over the last few years trying to figure
out a way to transfer this information to responsible people in the
government without making it public.  I gave up because if FBI agents
could not convince people above them to pay attention to this group of
Arabs learning to fly--but not land--large airplanes then they
certainly were not going to pay a bit of attention to someone who just
had an idea they were not likely to understand.

In spite of all the problems, including this one, vast numbers of
nuclear reactors are one of the few central power plant approaches to
replacing coal and doing something about global warming.

The only other approach I know about is solar power satellites, lifted
to GEO either with rockets or a space elevator.  If nanotube cable can
be made at low cost and strong enough, then a mechanically powered
elevator is possible.  (Per the presentation I created for the recent
ESA conference.)

But if this idea for making high purity plutonium 239 gets used by
terrorists to nuke an American city, this puts it in the historical
record of which cult caused it to be made public.  :-(

Keith Henson