Polonium subjects were chosen because experimenters wanted persons who had not been exposed to polonium either through work or accident. All subjects had incurable diseases. Excretion of polonium was followed, and an autopsy was conducted at that time on the deceased patient to determine which organs absorbed the polonium. Patients' ages ranged from 'early thirties' to 'early forties'. The experiments were described in Chapter 3 of Biological Studies with Polonium, Radium, and Plutonium, National Nuclear Energy Series, Volume VI-3, McGraw-Hill, New York, 1950. Not specified is the isotope under study, but at the time polonium-210 was the most readily available polonium
Operation Sandstone month. A "Fat Man" core required about of plutonium, of which 21% fissioned. Plutonium production fell off during 1946 due to swelling of the reactors' graphite neutron moderators. This is known as the Wigner effect, after its discoverer, the Manhattan Project scientist Eugene Wigner. These reactors were also required for the production (by irradiation of bismuth-209) of polonium-210, which was used in the initiators, a critical component of the nuclear weapons. Some of bismuth-209 had to be irradiated for 100 days to produce 600 curies of polonium-210, a little over . Because polonium-210 has a half-life of only 138 days,