Reflector Materials:

A reflector gets its name from the fact which neutrons leaving the reactor core hit the reflector and is returned to the core. The major consideration for choose a reflector material is its nuclear properties.   The necessary needs for reflector material used in a thermal reactor are:

1. Low  macroscopic  absorption  (or  capture)  cross  section  to  reduce  loss  of neutrons

2. High macroscopic scattering cross section to minimize the distance among scatters

3. High logarithmic energy decrement to make the most of the energy loss per collision because of low mass number

4. Temperature stability

5. Radiation stability

In that case of a fast reactor, neutron thermalization is not desirable, and the reflector that will consist of a dense component of high mass number.