Question

10-Ci point source of 24Na is to be stored at the bottom of a pool
of water. The radionuclide emits two photons per disintegration with
energies 2.75 MeV and 1.37 MeV in decaying by β–emission to stable
24Mg. How deep must the water be if the exposure rate at a point 6
m directly above the source is not to exceed 20 mR/h? What is the
exposure rate at the surface of the water right above the source

Answer 1