A by-product of some fission reactors is the isotope , which is an alpha emitter with a half-life of 24 000 years:
Consider a sample of 1.0 kg of pure at t = 0. Calculate (a) the number of nuclei present at t = 0 and (b) the initial activity of the sample. (c) How long does the sample have to be stored if a “safe” activity level is 0.10 Bq