Light water nuclear reactor (lwr), in particular pressurized water reactor (pwr) or boiling water reactor (bwr), with a heat sink on the ground and incorporating an autonomous decay heat removal (dhr) system

A light water nuclear reactor (LWR), comprising:

• a reactor core;
• a cooling circuit comprising a heat exchange device connected in a closed loop to a take-off device for taking off steam from the primary or secondary circuit of the reactor and a first pump for supplying the take-off device of the primary or secondary circuit with water from the heat exchange device;
• a system for removing at least a part of the decay heat of the reactor core, the system comprising:
• a first water reservoir or pool, arranged below the steam generator, wherein the heat exchange device is immersed so that the water contained therein cools the steam coming from the take-off device;
• an organic Rankine cycle (ORC) engine comprising:
• an expander;
• a condenser,
• a second pump;
• an evaporator arranged in contact with the pool so that the latter constitutes the heat source of the ORC;
• a fluidic circuit wherein a working fluid flows in a closed loop, the fluidic circuit connecting the expander to the condenser the condenser to the second pump, the second pump to the evaporator, and the evaporator to the expander;
• a second water reservoir, separate from the pool, and a third pump connected to the second water reservoir and to the condenser of the ORC in order to supply the latter with water, as the heat sink of the ORC.