1 metric ton = 1,000 kilograms = 2,200 lbs. Approximately 22 lbs. of fissile plutonium is required for one fission (not thermonuclear) "bare" warhead weapon. (34 x 2,200)/22 = enough "stuff" for about 3,400 sizeable bangs.

(For additional information on the amount of fissile material required for various types and designs of weapons, as well as a brief discussion of the nuclear reactions associated with reactors and weapons, see this.)

Preferred by nuclear states worldwide for its rapid fission rate, the ₉₄Pu²³⁹ isotope of plutonium has a half-life of around 24,000 years.  (94 is the number of protons in the nucleus and is the "atomic number", 239 the total number of protons and neutrons which approximates the "atomic weight")  So, it's not going anywhere all by itself anytime soon. This wonder material is easily manufactured in a "breeder" reactor that is powered by the controlled fission of  ₉₂U²³⁵ or previously produced Pu-239 nuclei. The non-fissile ₉₂U²³⁸ isotope of uranium, which constitutes the bulk of the uranium in the reactor fuel, will absorb a neutron, if it has been slowed or "moderated," and through a series of nuclear reactions "transmute" into plutonium.  The non-fissile U-238 isotope of uranium  is much more common, about 99% of naturally occurring uranium,  than the U-235 isotope which is fissile. U-235 can be used in nuclear reactors or in weapons depending upon the percentage of U-235 in the material. Over 90% U-235 is considered "weapons grade."

What the Iranians are up to is trying to extract the 0.7 % of naturally occurring U-235 using a centrifugal separation process that exploits the slight difference in isotope mass as the separation process principle. (Bet they wish they had one of them "breeders"!) This is done while the material is in a gaseous state as the compound uranium hexafluoride or UF₆, since solid uranium wouldn't work too well. That would be like having rocks in the spin cycle of your washing machine. Lot's of noise, no separation.

Aren't chemistry and nuclear physics fun? I learned all this on Iranian Sesame Street.

Note that the word "verify" does not appear in the AP article. However, "U.S. contribution will be capped at $400 million." We have to pay them to dispose of the fissile material? When they could sell it to Iran? And save us the money? After all, we need it for Saudi oil. Maybe, just maybe, the Russians will double dip? Take our money and still sell the stuff?  Nah! How silly of me to think so. Putin would never do anything like that. Would he? And putting the disposal process on the "slow track" by using a small reactor to "burn" the plutonium gives them additional time to play games. Wouldn't it would go a lot faster if they just made bombs out of the material and popped 'em off. Not targeting us, of course! Maybe blow up a few comets, like in the movies?

How do we get suckered into these deals and why should we trust the Russians?