Question

Are nuclear power plants safe to operate? Please explain how they can be kept safely operated and communities kept from exposure to radioactivity, how they deal with waste, and how they prevent the diversion of nuclear materials to nuclear weapons.

Answer 1

The most efficient fission reactions occur with slow neutrons. Thus, the fast neutrons ejected during fission must be slowed down by collisions with atoms of comparable mass that don ont absorb them, Such materials are called moderators. The most commonly used moderators are ordinary water and graphite. The most efficient modeator is helium. The next efficient one is heavy water but this is so expensive that it has been used only in research reactors.

Boron or cadmium steel rods are used as control rods. These rods absorb neutrons and thereby control the rate of fission.

Liquid alloy of sodium and potassium is used as coolant: it takes away the heat to the exchanger. Heavy water, polyphenyls and carbondioxide have also been used as coolants.

The nuclear weapon is enclosed is a steel containment vessel, which is housed in a thick-walled concrete. Operating people are protected by a shield of compressed wood fibres.