Plutonium is not the "most toxic", but like all transuranium elements (except neptunium), it gets absorbed in bone marrow. I believe that the total level allowed for an adult is .04 microcurie or equivalent to .6 microgram absorbed. The allowed "working" level (8 hours exposure) is 30 picogram/cubic meter of air. So yes, it is quite nasty. It is always present in minutes quantities in uranium ores, due to the transmutation of uranium (238, the most abundant isotope) to plutonium 239 by the absorption of "thermal" neutron.
As for Korea, their original "plan" was to separate Pu(239) from spent fuel rods, the closing of that processing plant (and agreement to send spent rods to other countries for processing) was the subject of the 1994 agreement. My understanding (from a PBS program on radio) is that in the last year or two, the NK started another program, separating U235 (the fissionable isotope, which like Pu239 can be used for atomic weapons) from natural uranium. It is actually a simpler route to atomic weapons since you do not have to have huge amounts of "spent rods" to extract the fissionable material, and once you perfect the process, the number of weapons you can make is not limited by the number of normal reactors that produce spent rods. In the past, some reactors were actually designed to optimize Pu239 production (breeder reactors), but the deal there was to get the fuel to be used twice, fission of U235 and from some of the thermal neutrons created by this reaction, convert U238 to Pu239 which also undergoes fission. I believe that breeder reactors were "killed" as part of the agreements to limit nuclear devices within the "big powers" arsenal.
So the question is still, why in the last year or two did NK decide to embark on the alternate route to nuclear weapons, and just last week, decided to also resume (reopen the Pu extraction labs) the program they agreed to close in 1994.
My own answer is dual, NK wants to blackmail the rest of the world with that program to get free energy and food, and we ourselves blundered by telling them you are "evil" and without "redemption, which they understood as "we have nothing to lose" since we are already branded. A political mistake just as bad as our Ambassador in Iraq telling Saddam, "what you do with Kuwait we will consider an internal affair", prior to Saddam invading Kuwait.
Zeev
PS, if we are going to engage in "which party screwed up more", I suggest we all move this discussion to the Political thread. I have copied this post there.
AI
