Systems, methods, and apparatuses for the passive removal of heat from inside the containment of a pressurized water reactor. The claimed method includes examining the interior of individual sections of piping using visual inspection equipment; assessing additional fluid resistance in piping in an inaccessible section by analysing a forced circulation mode in a circulation loop; determining the proportion of blocked tubes from among the total number of tubes in a heat exchanger; and processing the data obtained in order to determine the state of the passive heat removal system. The claimed device comprises at least one cooling water circulation loop, and further comprises a heating tank partially filled with water and having electrical heating elements; a drain line including a tank for receiving water drained from the system; and measuring means. The technical result is an increase in the operating safety of a nuclear power station.

A molten salt reactor system includes a fuel salt system configured to circulate a molten salt through a reactor vessel. The molten salt reactor system further includes an inert gas system fluidically coupled with the fuel salt system and configured to maintain a pressurized volume in a head space of a drain tank by circulating an inert gas along a first inert gas flow path. The molten salt reactor system further includes an equalization system configured to equalize pressure between head spaces of the reactor vessel and the drain tank in response to a reactor shutdown event. The inert gas system is configured to cease maintenance of the pressurized volume in response to the reactor shutdown event.