Holtite™ is the trademarked name of Holtec’s proprietary neutron shield material that is used for absorbing thermalized neutrons in a neutron-emitting environment.  Holtite was first used in the fleet of Holtec’s HI-STAR 100 casks built by Holtec in the late 1990s. Since then Holtite™ has been the neutron shield of choice in Holtec’s transportation and transfer casks and even a vertical ventilated cask (HI-STORM MIC) to reduce the neutron dose to infinitesimal levels adjacent to the cask.

All Holtite™ formulations consist of a hydrogen rich polymer impregnated with uniformly dispersed boron carbide particles. The operating temperature and thermal conductivity requirements determine which of the several qualified formulations of Holtite™ (denoted as Holtite A, Holtite B, etc.) should be used. The selection of the optimal Holtite™ formulation from among those qualified by extensive testing is guided by the competing considerations of temperature tolerance (thermal stability) and thermal conductivity.

In addition to casks, Holtite™ can be used in any nuclear application that entails capture of neutrons. Potential applications outside of used fuel devices in commercial nuclear and defense plants include reprocessing and enrichment facilities.