Aluminum boron carbide (Al-B4C) material is widely used in the fuel storage racks as a neutron absorber for criticality safety, its effectiveness is reduced when neutrons pass through the absorber sheet without attenuation by B4C particles, i.e., neutron channeling effect. This paper investigates the effect of B4C particles size and particle arrangement on spent fuel storage criticality for both wet storage and dry storage conditions. Different models of neutron absorber sheet in spent fuel storage racks are established based on experimental and test data of neutron absorber sheet used in third generation nuclear power plant in China. The results show a weak correlation between particle size and multiplication factors when particle size is smaller than 100 μm. Neutron channeling effect is less significant for random sampling arrangement of B4C particles than that for uniform arrangement. In addition, for practical purposes, contrast analysis against percent credit absorber sheet model is carried out and the results confirm a good conservation of 95% credit for 10B. The result provides a strong evidence for the use of 95% credit for 10B in criticality safety analysis for spent fuel storage using aluminum boron carbide as neutron absorber.