Measurement of 14-MeV Neutron Multiplication in Thorium Oxide

The measurement of 14-MeV neutron multiplication is given for a 4-cm-thick thoria assembly in rectangular geometry. This agrees within 2% of the corresponding calculated value of neutron multiplication obtained by using the general geometry Monte Carlo code MORSE-E and the Los Alamos National Laboratory 30-group neutron cross-section set Claw-IV in P₃ scattering approximation. The results confirm Kushneriuk and Wong's calculational analysis of the Shief et al. experiment with a large cylindrical thorium metal assembly using the ENDF/B-IV library, as well as Kobayashi et al. 's differential neutron spectrum measurements in a spherical thoria pile and thorium metal slab by the time-of-flight method.