Advanced neutron shielding material using zirconium borohydride and zirconium hydride

Neutron transport calculations have been carried out to assess the capability of zirconium borohydride (Zr(BH4)4) and zirconium hydride (ZrH2) as advanced shield materials, because excellent shields can be used to protect outer structural materials from serious activation. The neutron shielding capability of Zr(BH4)4 is lower than ZrH2, even though the hydrogen density of Zr(BH4)4 is slightly higher than that of ZrH2. High-Z atoms are effective in neutron shielding as well as hydrogen atoms. The combination of steel and Zr(BH4)4 can improve the neutron shielding capability. The combinations of (Zr(BH4)4 + F82H) and (ZrH2 + F82H) can reduce the thickness of the shield by 6.5% and 19% compared to (water + F82H), respectively. The neutron flux for Zr(BH4)4 is drastically reduced in the range of neutron energy below 100 eV compared to other materials, due to the effect of boron, which can lead to a reduction of radwaste from fusion reactors.