Water as a gamma radiation shielding
In short, effective shielding of gamma radiation is in most cases based on use of materials with two following material properties:
- high-density of material.
- high atomic number of material (high Z materials)
Although water is neither high density nor high Z material, it is commonly used as gamma shields. Water provides a radiation shielding of fuel assemblies in a spent fuel pool during storage or during transports from and into the reactor core. Although water is a low-density material and low Z material, it is commonly used in nuclear power plants, because these disadvantages can be compensated with increased thickness.
Half Value Layer of Water
The half value layer expresses the thickness of absorbing material needed for reduction of the incident radiation intensity by a factor of two.
Table of Half Value Layers (in cm) for a different materials at gamma ray energies of 100, 200 and 500 keV.