All uranium is radioactive.
The nucleus will have the same mass as before the beta decay, but will have one less neutron and one more proton gamma decay-occurs by rearrangement of protons and neutrons in the nucleus and the emission of a gamma ray. Nuclear Weapons Small amount of U-235 will just emit neutrons and heat. An atomic bomb works by forcing two small amounts of fissionable material together very rapidly, causing the reaction to go critical. A hydrogen bomb uses an atomic bomb to generate the extreme temperatures required for the fusion reaction to proceed. Radioactive Tracers Extensively used in medicine, agriculture, geology.