The effective delayed Neutron fraction for Bare-metal criticals

摘要

Given sufficient material, a large number of actinides could be used to form bare-metal criticals. The effective delayed neu- tron fraction for a bare critical comprised of a fissile material is comparable with the absolute delayed neutron fraction. The effective delayed neutron fraction for a bare critical composed of a fissionable material is reduced by factors of 2 to 10 when compared with the absolute delayed neutron fraction. When the effective delayed neutron fraction is small, and extreme caution must be used in critical assemblies of these materials. This study uses an approximate but realistic model to survey The actinide region to compare effective delayed neutron frac- Tions with absolute delayed neutron fractions.