Micro nuclear reactor having a heat pipe extending into a core comprising fuel particles mixed with moderator particles, where the particles can be gravity discharged from the core through a bottom outlet

A nuclear reactor comprising:

• a core containing granular particles of nuclear fuel mixed with granular particles of moderator material;
• a heat pipe comprising an evaporator end in the core and a condenser end out of the core;
• a power converter arranged to receive heat from the condenser end of the heat pipe, wherein the power converter is operable to convert thermal energy into electrical energy;
• an outlet located at a lower portion of the core, wherein the outlet when open allows for gravity discharge of the nuclear fuel and the moderator material out of the core;
• and
• a valve configured to open and close the outlet,
• wherein the valve is configured to open responsive to a predetermined condition,
• wherein the valve when open causes gravity discharge of the nuclear fuel and the moderator material from the core through the outlet.