CATHARE modelling of the HELIOS loop for the study of heat transfer to supercritical helium flowing in pipes following loss of insulating vacuum

•HELIOS experiment is modified to study vacuum loss on supercritical helium pipe.•HELIOS new design is investigated with the thermal hydraulic code CATHARE.•First verification of CATHARE results for a cryogenic device with diphasic helium.•The methodology to quantify the heat flux is investigated with CATHARE.