Since alpha and beta particles can be easily shielded against, they do not present a major problem
in the nuclear reactor plant.
The important information in this chapter is summarized below.
Shielding Materials Summary
Low mass number and high cross section (preferably hydrogenous material)
for low energies. Water ranks high due to advantage of low cost, ready
means for removing heat.
Good inelastic scattering properties (high energies). Iron is used due to the
large change in neutron energy after collision but it has little effect on
lower energy neutrons.
High atomic mass number and high density are required to attenuate g
radiation. Lead has advantage of ease of fabrication. The disadvantage of
lead is its low melting point. Iron is used for higher and lower energies.
Iron is selected based on structural, temperature, and economic
considerations. Water can be used but requires large amounts because
water is a poor absorber of gamma radiation. Concrete is a good gamma
attenuator as a general shield material. Concrete is strong, inexpensive,
and adaptable to different types of construction.
Alpha and Beta Radiation
No particular shielding material is required to guard against alphas and