Challenge problem:Critical mass is the smallest amount ofradioactive material necessary to sustain a nuclear chain reaction.Uranium-235, the isotope of uranium used in the \"little boy\" bombdropped on Hiroshima during Wordl War II,has a critical mass of 52kg. How many long tons of yellowcake (64% uranium by mass) need tobe processed to produce a critical mass of U-235? The percentnatural abundance of U-235 is 0.72% and its nuclide mass is235.0439 amu.
1 long ton = 2240 lb., 1 kg = 2.20 lb.
