Selection of cladding material:

The selection of cladding material for fast reactors is less dependent upon the neutron absorption cross section than for thermal reactors. The necessary needs for these materials are retention of satisfactory physical, high melting point and mechanical properties, a low swelling rate when irradiated through huge fluences of fast neutrons, and good corrosion resistance, especially to molten sodium. Now, stainless steel is the preferred fuel cladding material for sodium-cooled fast breeder reactors (LMFBRs). For such reactors, the capture cross section is not as important as for thermal neutron reactors.

In the year of 1977 the Carter Administration deferred indefinitely the reprocessing of nuclear fuels from commercial power reactors. This led the electric utility organization to conduct research on high-burnup fuels and programs which would permit an increase in the length of time in which the fuel rods remain in the reactors. High integrity and performance of fuel cladding will become even more significant as these high-burnup fuel rods are designed and programs for extended burnup of nuclear fuels are placed within operation.