Extrapolation distance in two-region spherical systems

Extrapolation distances for the neutron flux distribution in bounded media are usually defined in such a way that agreement is obtained between diffusion theory and transport theory. A typical application is the interpretation of pulsed neutron experiments. In this work we extend the conventional treatment of extrapolation distances to two-region spherical bodies. Assuming neutrons of one speed, extrapolation distances are calculated for a large number of critical and time-dependent systems. Among other things it is found that the inner region has a large influence on the extrapolation distance at the outer surface. 6 refs