Simulation study of coupling for active neutron multiplicity counting on New Pile Laboratory—Neutron Multiplicity Counter

This paper describes all-process direct simulation of active neutron multiplicity counting on New Pile LaboratoryNeutron Multiplicity Counter (NPL-NMC). Twenty-eight hemispheroidal shell uranium components with an inner radius of 1.2 cm were simulated by MCNPX code, which had different mass but the same enrichment and density. The relation curve between coupling and multiplication was obtained. The mass deviation of simulation measurement was within 1.5% for the hemispheroid and hemispheroidal-shell (inner radius 1.2 cm) uranium components, while the mass deviation was lower 5%-10% for the hemispheroidal-shell (inner radius 3.2 cm) and cylinder(inner radius 6, 8 cm) uranium components.