Neutron-activation analysis of geologic samples for gold and associated elements using a power reactor

The method of neutron-activation analysis (NAA) using research reactors as neutron sources is widely used in the elemental analysis of rocks and ores. Because of the limited access to research reactors, however, it is difficult case, power reactors are promising for use in NAA. The authors investigated the possibility of using a power reactor for NAA of geological samples for gold and associated elements. Because of the difficult access to the channels passing through the active zone of the reactor, the samples were irradiated in the reserve channel for ionization chambers situated outside the active zone in the graphite reflector. The determination of gold by the NAA method is based on the radiative capture reaction 197Au(n, γ)198Au (T12 = 65 h) and subsequent detection of 412-keV γ rays. Gold containing samples and standards pulverized to a particle size of 200 mesh were prepared for the analysis. The sensitivity thresholds of a wide range of elements accompanying gold, which are well activated by thermal and resonance neutrons, were also evaluated