Neutron number first-passage time distribution and the reactor time constant

Abstract

The reactor time constant is described deterministically. In the present work, the random variable corresponding to the reactor time constant -the random time at which the random neutron number process in the reactor reaches a prescribed level -is studied stochastically. The statistical distribution containing the first-passage time as a thermodynamic parameter is used. The reactor time constant is related with the dynamics of the system. The neutron number first-passage time distribution is also described taking account of the system dynamics over the entire evolution time of the system. The reactor kinetics in powergeneration regimes, self-regulation due to feedback, and the behavior of a transient process with a positive reactivity perturbation are considered as examples.