Irreversible circulation of fluctuation in coupled-core nuclear reactors.

Abstract

The irreversible circulation α of fluctuation a for a coupled-core nuclear reactors is derived. Neutrons in this system are transported from a certain core to another one with a finite time lag and their fluctuations are generally described by a set of non- Markoffian Langevin equations. This system cannot accept Tomita's original theory based on the Markoffian stochastic process. When the system has the exp(-t/τ)-type memory kernel, we can, however, build up an equivalent Markoffian model—points model—by introducing “transit zones”, and we can evaluate the irreversible circulation of fluctuation α. The α for symmetrically coupled-cores takes null-value, while for an asymmetrical case the α becomes finite and turns out to be a new information from which the coupling parameters between the cores can be extracted.