Application of a two energy group analytical solutions to the YALINA experiment SC3A

The SC3A experiment in the YALINA-Booster facility in Belarus is described and investigated. For this investigation the very special configuration of YALINA-Booster core, consisting of a fast and a thermal zone, decoupled with a neutron ‘valve’is analyzed based on a full HELIOS model for the calculations. The effect of the two region design on the experimental results at different detector positions is leading to unexpected results and the special problems for the analysis of the experiments have been shown. For a more detailed representation, a recently developed two group analytical solution for the time dependent diffusion equation obtained by Green’s function method without separation of space and time was used. To model the above mentioned streaming of neutrons from the thermal area into the fast area an analytical solution for the time dependent neutron flux with two sources has been developed from the available Green’s functions for two groups. In addition to the central source pulse of the external source a source at the boundary of the system has been introduced. The new analytical solution shows very good agreement with the experimental results, even for the unexpected behavior of the outermost deterctor. Thus analytical solution without separation of space and time are a very promising tool to develop a new method for the analysis of ADS experiments.