1.9.2.1 Neutronic Properties

Neutronic properties are of significant consideration in the design and develop­ment of nuclear reactors. As discussed earlier, the fission chain reaction requires continued supply of neutrons for it to proceed and that is why neutron economy plays an important role. Fuel cladding materials need to have a lower neutron absorption cross section and that is why zirconium alloys are used in LWRs (see Appendix 1.A). On the other hand, to control the chain reaction, the control materi­als should have high neutron absorption cross section. The same consideration would also apply to shielding materials.