Method of operating a nuclear power plant

A nuclear power plant comprising:

• a molten salt reactor (MSR) to produce heat, the MSR comprising a vessel;
• a heat exchanger system;
• radioactivity detectors positioned outside the vessel;
• shutoff mechanisms positioned outside the vessel;
• and
• an end-use system,
• the MSR comprising a graphite moderator core positioned in the vessel, and a molten salt circulating at least in the vessel, the molten salt to transfer the heat produced by the MSR to the heat exchanger system, the graphite moderator core defining one or more than one through hole, the vessel being sealed to permanently integrate the graphite core into the vessel,
• the heat exchanger system having an inside portion located inside the vessel and an outside portion located outside the vessel, the inside portion comprising a plurality of heat exchangers in fluid communication with the one or more than one through hole of the graphite moderator core,
• each heat exchanger having an inlet conduit and an outlet conduit, each inlet conduit and each outlet conduit extending from each respective heat exchanger, through the vessel, toward the outside portion of the heat exchanger system and connecting each respective heat exchanger to the outside portion of the heat exchanger system,
• each heat exchanger having associated thereto a respective radioactivity detector, each radioactivity detector arranged to detect radioactivity present in a coolant salt circulating in the respective heat exchanger,
• each shutoff mechanism arranged to shut off circulation of the coolant salt circulating in the respective heat exchanger when radioactivity beyond a threshold amount is detected, by the respective radioactivity detector, in the respective heat exchanger.

A nuclear power plant comprising:

• an integral molten salt reactor (IMSR) comprising:
• a vessel, the vessel comprising:
• a graphite moderator core, the graphite moderator core defining one or more than one through hole;
• a molten salt circulating within the vessel and within the one or more than one through hole, the molten salt for receiving heat produced by the IMSR;
• and
• heat exchangers, each heat exchanger defining a volume;
• conduits connecting the heat exchangers to an outside the vessel and to an end use system, each conduit comprising a coolant salt circulating within, the coolant salt for receiving heat from the molten salt and providing the heat to the end use system located at the outside of the vessel, the conduits comprising inlet conduits and outlet conduits, each heat exchanger having connected thereto an inlet conduit and an outlet conduit, the inlet conduit to circulate coolant salt away from the heat exchanger to which it is connected, the outlet conduit to circulate coolant salt toward the heat exchanger to which it is connected;
• radioactivity detectors, each radioactivity detector having associated thereto a respective heat exchanger;
• pressure detectors;
• and
• shutoff mechanisms, each inlet conduit having associated thereto a respective shutoff mechanism, each outlet conduit having associated thereto a respective shutdown mechanism, each radioactivity detector for detecting radioactivity present in the coolant salt circulating in the heat exchanger associated to the respective radioactivity detector, at least one of the inlet conduit and the outlet conduit of each heat exchanger having a respective pressure detector connected thereto, each pressure detector for monitoring pressure of the coolant salt in the inlet conduit or the outlet conduit to which the pressure detector is connected, the shutoff mechanisms to shut off circulation of the coolant salt within the inlet conduit and the outlet conduit of a particular heat exchanger when at least one of:
• (a) the radioactivity in the particular heat exchanger exceeds a pre-determined threshold amount, and
• (b) the pressure in the at least one of the inlet conduit and the outlet conduit of the particular heat exchanger changes, wherein in the event that the shutoff mechanism shuts down the particular heat exchanger, the remaining heat exchangers still function and the IMSR continues to operate.