Generating the flux map of Nigeria Research Reactor-1 for efficient neutron activation analysis

Abstract

One of the main uses to which the Nigeria Research Reactor-1 (NIRR-1) will be put is neutron activation analysis. The activation analyst requires information about the flux level at various points within and around the reactor core to enable him identify the point of optimum flux (at a given operating power) for any irradiation scheme. A method has been developed to calculate and plot a two-or three-dimensional thermal flux profile of this Miniature Neutron Source Reactor (MNSR) over any vertical plane of symmetry through the axis of the core. It thus provides valuable information to neutron activation analyst, information which hitherto could only be obtained by a cumbersome and expensive process of trial and error. The scheme combines the lattice code WIMS and core analysis code CITATION to generate the required group constants and carry out the neutronic calculations respectively. It is shown that the neutron flux peaks not only in the annular and bottom beryllium reflectors but also within the core and inside the top beryllium shim tray. This work will result not only in savings in time and resources, but will also serve to provide useful information to the MNSR designer on where to locate more irradiation sites in future designs or modification.

Nigerian Journal of Physics Vol. 16(2) 2004: 135-141