A fast reactor core includes a sodium plenum installed above the fuel. The sodium plenum is capable of reducing a void reactivity. During operation, a tip of a primary control rod is inserted in a core fuel region, and a tip of a backup control rod is arranged near an upper end of the sodium plenum.

This disclosure describes various configurations and components of a molten fuel fast or thermal nuclear reactor for managing the operating temperature in the reactor core. The disclosure includes various configurations of direct reactor auxiliary cooling system (DRACS) heat exchangers and primary heat exchangers as well as descriptions of improved flow paths for nuclear fuel, primary coolant and DRACS coolant through the reactor components.

The invention concerns a liquid metal-cooled fast-neutron nuclear reactor (1), comprising a system (2) for removing at least part of both the nominal power and the residual power of the reactor, which ensures, at the same time: removal of the residual power in a totally passive manner from the initial instant of the accident; removal of the heat through the primary vessel; implementation of a final cold source (container with PCM) other than the sodium/air or NaK/air heat exchangers used in the prior art.

An assembly to be inserted into a nuclear reactor, such as a liquid sodium-cooled fast neutron reactor, includes an assembly hollow body of elongate shape along a longitudinal axis X. The wall of the hollow body includes at least one through-opening. The assembly also includes an assembly element inserted into the hollow body. The assembly element includes at least one flexible blade of which the free end is shaped into a clip-fastening hook collaborating in clip-fastening fashion with the through-opening from inside the hollow body, so as to connect the assembly element to the hollow body. The assembly also includes at least one removable structure for locking the flexible blade clip-fastened into the through-opening. The removable locking structure makes it possible to prevent the flexible blade from flexing and thus the removable locking structure makes it possible to lock a connection between the assembly element and the hollow body.

The invention concerns a nuclear reactor, comprising a vessel closed at the top by a radially external fixed closing structure and by a radially internal mobile closing structure and containing a core, immersed in a primary cooling fluid and comprising fuel elements and control and shutdown rods, and a hydraulic separation structure delimiting a hot manifold and a cold manifold in which the primary fluid circulates; the control rods and shutdown rods are inserted in respective penetrations of the fixed closing structure and are therefore located radially external to the mobile closing structure and external to an upper portion of the separation structure containing respective heads of the fuel elements.

The invention concerns a nuclear reactor, comprising a vessel closed at the top by a radially external fixed closing structure and by a radially internal mobile closing structure and containing a core, immersed in a primary cooling fluid and comprising fuel elements and control and shutdown rods, and a hydraulic separation structure delimiting a hot manifold and a cold manifold in which the primary fluid circulates; the control rods and shutdown rods are inserted in respective penetrations of the fixed closing structure and are therefore located radially external to the mobile closing structure and external to an upper portion of the separation structure containing respective heads of the fuel elements.

Configurations of molten fuel salt reactors are described that allow for active cooling of the containment vessel of the reactor by the primary coolant. Furthermore, naturally circulating reactor configurations are described in which the reactor cores are substantially frustum-shaped so that the thermal center of the reactor core is below the outlet of the primary heat exchangers. Heat exchanger configurations are described in which welded components are distanced from the reactor core to reduce the damage caused by neutron flux from the reactor. Radial loop reactor configurations are also described.

Configurations of molten fuel salt reactors are described that allow for active cooling of the containment vessel of the reactor by the primary coolant. Furthermore, naturally circulating reactor configurations are described in which the reactor cores are substantially frustum-shaped so that the thermal center of the reactor core is below the outlet of the primary heat exchangers. Heat exchanger configurations are described in which welded components are distanced from the reactor core to reduce the damage caused by neutron flux from the reactor. Radial loop reactor configurations are also described.

Configurations of molten fuel salt reactors are described that include an auxiliary cooling system which shared part of the primary coolant loop but allows for passive cooling of decay heat from the reactor. Furthermore, different pump configurations for circulating molten fuel through the reactor core and one or more in vessel heat exchangers are described.

Configurations of molten fuel salt reactors are described that include an auxiliary cooling system which shared part of the primary coolant loop but allows for passive cooling of decay heat from the reactor. Furthermore, different pump configurations for circulating molten fuel through the reactor core and one or more in vessel heat exchangers are described.