Background: The neutron absorbing materials used for spent fuel storage grids in the nuclear power plant need to meet the structural and functional integration requirements. Purpose: This paper has proposed the high content B4C/Al neutron absorbing materials reinforced by carbon fiber. Methods: Monte Carlo method has been used to calculate the neutron transmittances of carbon-fiber reinforcing B4C/Al neutron absorbing materials (Cf/B4C/Al). Result: The effects of some factors on the neutron transmittances of Cf/B4C/Al composite have been studied such as B4C and Cf contents

incident neutron energy and material thickness

which also have been compared with those of B4C/Al materials. Conclusions: The results show that for 1 eV?0.1 MeV incident neutron

when the content of B4C is less than 35%

the addition of carbon fibers can significantly improve the neutron shielding performance of B4C/Al composite. For 100-eV incident neutron

the transmittance of the material decreases exponentially with the increase of B4C content. The neutron transmission of Cf/B4C/Al decreases with the increase of carbon fiber content up to 10%. The optimal component ratios of Cf/B4C/Al were designed as 35% B4C and 10% Cf. In order to shield the neutron radiation as effectively as a 0.5-mm-thick cadmium plate

the thickness of Cf/B4C/Al was also designed as 9.42 mm. The study will provide the theoretical guidance for the design and application of the neutron absorbing materials. Abstract