Remarks on the functional equivalence of two approaches to the space-dependent reactor noise

The two approaches (two-group diffusion theory and one-group theory with slowing down kernel) which provide the theoretical justification of the separation of the neutron noise in water moderated reactors into a local and a global component are reviewed, and it is shown that the solutions obtained by either method are equivalent. Subsequently, the differences between the two methods are investigated, by applying them to a simple physical problem. (author)