AbstractThe neutron leakage multiplications from hollow beryllium spheres with shell thicknesses of 4.6 cm, 6.99 cm, 7.87 cm, 9.38 cm, 13.8 cm and 19.9 cm have been experimentally determined using a Bonner sphere spectrometer. The fluences with and without the shells interposed between a DT neutron source and the Bonner sphere spectrometer were used to determine the leakage multiplications for various shell thicknesses. Preliminary calculations of the neutron leakage multiplications have also been performed by modeling the experimental setup using MCNP with the LANL beryllium cross-section evaluation and ENDF/B-V cross sections. The agreement of the preliminary calculated values with the experimental leakage multiplication values range from 1% to 15%, the best agreement being for the intermediate shell thicknesses.