[Gorzaloon]

at one point Lazar was even selling unused reactor fuel pellets. Completely useless for building a weapon or a reactor (he'd only sell you one), but it was still suprising to see that high-radiation items like that can be sold legally.

If they are fast breeder "fuels" such as U238 or Thorium 232, it is legal. Natural isotopes are license exempt in less than 100 MicroCurie amounts. With natural isotopes at low specific activities, that amount can be many pounds.

If it is LEU, he cannot be selling it, or possessing it without a Special Nuclear Materials License.

Radiologically, the Americium 241 in smoke detectors have energetic alpha, and should be at least as deadly as Po210.

[GSlob]

Not quite. the amounts are pretty small, and half-life is much longer - centuries instead of months. The polonium stinkers chose optimal half-life- long enough to last from preparation to application, and short enough to hope that it would decay before being detected.