Concrete is considered to be an excellent and versatile
shielding material and is widely used for reactor
shielding. If there are no limitations in regards to
space or weight, ordinary or conventional concrete
made from local materials is usually considered as a
very suitable and economical material for the
construction of radiation shielding against 7-rays and
neutrons. Special concretes can, however, be made to suit
special needs. Thus concrete which is more effective
for the attenuation of fast neutrons can be produced
by increasing the water content through the use of
hydrous aggregates such as serpentine and limonite.
For shields which are required to provide protection
mainly against gamma radiations and which have
limitations in regard to thickness, it may be desirable
to use heavy concretes which have densities greater
than ordinary concrete. For this purpose special heavy
aggregates such as hematite, ilmenite and cast iron
or steel scrap may be used (Jaeger, 1975; Profio, 1979;
Chilton et al., 1984; Kaplan, 1989).