Uranium-235
Uranium-235 is an
isotope that differs from its other isotope,
uranium-238, by its ability to cause a rapidly expanding chain
fission reaction. It absorbs a
thermal neutron and splits into two lighter substances by way of
thermonuclear fission. It either releases 2 or 3
neutrons and continues the reaction. In
nuclear reactors, the reaction is slowed down by the addition of
control rods which are made of
elementss such as
boron and
cadmium which can absorb a large number of neutrons without decaying. In nuclear bombs, the reaction is uncontrolled and the large amount of
energy released creates an
explosion.