Neutronic parameters of a low enrichment core in reactor LR-0 for MSR research

The study of the reactivity effects, which are in many cases negligible, is not a simple task. Consequently, the special core configuration with high sensitivity to low introduced reactivity changes was developed at LR-0 reactor. It proved to be suitable for precise definition of any material, in terms of its impact on reactivity, being inserted into a reactor core. The results also imply this kind of core configuration to be applicable for the planed precise measurement of the MSR FLIBE salt temperature reactivity coefficients. This paper also examines the agreement between calculations and experiments for some cases of the low reactivity introduction into the core. Besides that, the similar cores can be used for purposes of neutron dosimetry, therefore the neutron spectrum in the experimental region was determined and compared with the results of MCNP calculations with the standard nuclear data libraries.