Review on neutron-absorbing fillers

Abstract In this chapter, the filler or powder materials used in the radiation shielding industry are presented. The current trend is the use of boron-based compounds, abundant materials with relatively accessible costs and with which developers have extensive experience. Today more efficient boron-based compounds are still being developed, although the use of rare earths, the materials with the highest absorption cross section known among all the stable nuclei, represents a great advance in this field. Despite this advantage, these rare earths, based mainly on the use of samarium and gadolinium, have the disadvantage of emitting very high-energy secondary gamma radiation and being very dense, so their use has to be studied. An optimal solution for the development of new neutron shields is the use of boron-based materials that incorporate rare earths, enabling a compromise to be achieved to develop optimal neutron absorption solutions for different energy spectra.