Example

We have considered the response of three detectors inside a non-multiplication media (Fig. 1) to a transient of neutron source (Fig. 2). The different answer, (P1/Diff) in Fig. 3, refers to a full treatment of the time dependence of the angular harmonics of the P1 approximation (P1) and a simplified approach (that leads to the well know diffusion time dependent equation) in which the time derivative of the first order angular harmonics is neglected (Diff).

Geometry

Source transient

Detector Response: Scalar Flux