PLENTIFUL ENERGY

and they decay to other elements that increase radioactivity deleterious to handling
in fabrication and in access to the weapons. The stated U.S. position is that they are
undesirable in weapons because they cause ―increased complexity in designing,
fabricating and handling them.‖ [8] The secrecy which surrounds weapons work,
completely appropriate in the main, does serve to blur and weaken absolute
statements of the possible and impossible. But what is clear is that impurities that
spontaneously produce neutrons, generate heat, and increase radioactivity, all
characteristics of spent fuel, are at best undesirable. It is the first-time acquisition of
nuclear weapons by irresponsible states and the clandestine acquisition of weaponsusable
material by groups seeking to cause terror that are of concern. Plutonium that
would require very significant sophistication in weapons fabrication, storage, and
detonation isn‘t a likely choice for weapons by a neophyte. The radioactivity of
reactor-grade plutonium makes it an unlikely choice for the hands-on work that is
necessary in any case.
12.5 The Subject of Plutonium
The existence of plutonium is not a matter for debate. That is a settled issue. The
world inventory of plutonium is on the order of two thousand tons, the bulk of
which now comes from civil nuclear power. In the main, it is contained in the spent
fuel rods from present nuclear power plants, largely from light water reactors. The
amount of separated plutonium in the world has increased in the last two decades.
The inventory of separated civil plutonium was about 230 metric tons in 2004.
[9,10] Plutonium fabricated into mixed plutonium-uranium oxide (MOX) fuel for
recycle in LWRs and the plutonium declared as excess weapons materials in the
U.S. and Russia is not included in this estimate. At the present time the commercial
reprocessing plants, La Hague in France, THORP in the U.K., and Rokkasho in
Japan, recover about thirty tons of plutonium per year. Not all this plutonium is
recycled back into LWRs, so the inventory of separated plutonium grows.
All nuclear power plants produce plutonium. Plutonium production is not a
matter of choice—it is produced as a matter of course in uranium-fueled reactors by
transformation of the most common isotope of uranium, U-238, first to Np-239 and
then in a few days by radioactive decay to Pu-239. The annual amounts produced
and left in the spent fuel of an LWR equal, and as a rule more probably exceed,
those produced in an IFR of equal power. The IFR, of course, produces more
plutonium, but it burns much more in place. Its fuel, after all, is plutonium. By
contrast, the LWR is fueled with fissile uranium and creates plutonium, and while it
burns a considerable amount of it in place, it also leaves a lot unconsumed in the
spent fuel.
There has been sporadic experimentation with thorium fuel reactors going all the
way back to the early years of reactor development. (In recent decades the thorium
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