This work is devoted to hydrogen safety security during severe accidents at NPP as well as the validation of equipment performance of passive safety systems under these conditions. The results of an experimental investigation of the performance of the primary means of measurement module of the hydrogen concentration control system under physicochemical actions on them due to the precipitation of insoluble aerosols, non-condensable gases, and oil vapor during severe accidents at NPP are presented. It is shown that the physicochemical actions do not significantly affect the performance of the primary means of measurement module of the hydrogen concentration control system.