Safety valves accurately control closure and opening of fluid passage through the valve. Valves include a barrier that blocks the fluid until removal only by a high-energy projectile. Following removal and opening, the barrier or the projectile can flow through the valve, which remains open. Bullets, pneumatic pistons, shot, coilgun pellets and any other forceful projectile may impact and remove the barrier. The projectile is actuated with any type of chemical reaction, firing pin, spring release, accelerating circuit, ignition circuit. Catchers in the valve envelop or otherwise retain the projectile or barrier pieces and enter the fluid flow of the opened valve without blocking it. Disruptable barriers include strong but breakable glass plates, thin steel sheets, a rotatable door and other barriers that can withstand potentially over 10,000 psi of fluid pressure while closing the valve. Valves can use circuits to both monitor valve open/closed status and initiate firing the projectile.

A nuclear reactor shutdown system includes a housing vessel that is disposed above a reactor core fuel housed in a nuclear core vessel in a hermetically sealed manner, houses a plurality of neutron absorbers, and has an opening enabling the neutron absorbers to pass through at a bottom, a shielded path that passes through the reactor core fuel to extend in an up-and-down direction, an upper end of the shielded path communicating with the opening of the housing vessel and a lower end of the shielded path being closed, and a communicating part that is disposed so as to close the opening and causes the housing vessel and the shielded path to communicate with each other when the communicating part reaches or exceeds a threshold temperature.

Disclosed is a micro nuclear reactor that includes a core filled with nuclear fuel and moderator which are formed of particles, a heat pipe inserted in the core and transferring outwards heat generated by a nuclear reaction, and a power converter receiving heat from a condenser of the heat pipe and converting thermal energy into electrical energy.

A nuclear power system has an open volume between containment vessel and a reactor vessel containing a reactor core. Located in the open volume is a container holding a neutron-absorbing chemical in solid form. The container is configured to release the chemical in solid form directly into the open volume in response to a predetermined temperature and/or a predetermined pressure within the open volume. The released chemical can assist in maintaining the reactor core in a sub-critical state.

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.

A micro nuclear reactor includes a core filled with nuclear fuel particles mixed with moderator particles. A heat pipe extends into the core and transfers heat generated by the core. A power converter receives heat from the heat pipe and converts thermal energy into electrical energy. A valve is configured to open and close an outlet located at a lower portion of the core. When the valve is open the nuclear fuel and the moderator are discharged by gravity from the core through the outlet.