A study on neutron kerma factors and photon air-kerma for human organs is presented for neutron energy range 2.53?10-8 MeV to 29 MeV and photon energy range 1 keV to 20 MeV. The human organs water equivalence for photon and neutron, is also presented. The ratio of the mass-energy absorption coefficients of human organs to water was found constant and unity above 100 keV, whereas there was a large difference for energies below 100 keV. The neutron kerma factors of human organs and water are found of same order of magnitude whereas differs for air. The neutron kerma factors of human organs and tissue substitutes were found to be equal to water for neutron energies between 63 eV and 200 keV. The skeleton-cortical bone was found to be away from water equivalence for low-energy photons and high-energy neutrons.

Mass at ten u a tion co ef fi cients, mean free paths and ex po sure buildup fac tors have been used to char ac ter ize the shield ing ef fi ciency of metal hy drides and borohydrides, with high den sity of hy dro gen. Gamma ray ex po sure buildup fac tors were com puted us ing five-pa ram e ter geomet ric pro gres sion fit ting at en er gies 0.015 MeV to15 MeV, and for pen e tra tion depths up to 40 mean free paths. Fast-neu tron shield ing ef fi ciency has been char ac ter ized by the ef fec tive neu tron re moval cross-sec tion. It is shown that ZrH 2 and VH 2 are very good shield ing ma teri als for gamma rays and fast neu trons due to their suit able com bi na tion of low-and high-Z el e ments. The pres ent work should be use ful for the se lec tion and de sign of blan kets and shield ing, and for dose eval u a tion for com po nents in fu sion re ac tors.