A mobile reactor radiation shielding solution prevents activation of structural materials to reduce a radiation dosage risk to living organisms and accelerates timetables for transport. The shielding solution can include: in-vessel neutron shield, in-vessel shadow shield, transport shield, and module shadow shield. In-vessel neutron shield reduces and prevents the activation of the structural materials and significantly reduces the need for heavy shielding to shield against the gamma emissions from activated structural materials. In-vessel shadow shield provides neutron and gamma shielding between the reactor and a balance-of-plant (BOP) module and control system. In-vessel shadow shield is placed near the active nuclear core to minimize size of the shield while maximizing the protected arc to shield radiation workers while preparing the nuclear reactor for transport. Transport shield is used during transportation when living organisms come into proximity of the reactor. Module shadow shield shields reactor control components and BOP module during operation.

Molten salt nuclear fission reactor including a core through which a fuel salt flows, a unit for circulating the fuel salt, a primary heat exchanger through which a heat-transfer salt flows, a primary enclosure which is impermeable to liquid salts and contains the reactor core, and a shelter. The reactor includes a parallelepiped matrix including alternating layers of fuel salt channels, and layers of heat-transfer salt channels. The matrix forms both the reactor core, in which the fission occurs, and the primary heat exchanger of the reactor. The circulating unit is entirely located within the primary enclosure and are configured to extract the fuel salt from one portion of the fuel salt channels on one side of the matrix and to propel the fuel salt into the other portion of the channels on the same side of the matrix.

A nuclear power generation system capable of generating power with robust shielding against ionizing radiation is provided. This nuclear power generation system includes: a nuclear reactor that includes a core fuel, and a reactor vessel that surrounds to cover the core fuel and to shield a space having the core fuel for shielding against ionizing radiation; a thermal conductor that is disposed inside of the reactor vessel, and transfers heat of the core fuel via solid thermal conduction; a refrigerant circuit that includes a pipe with a part inserted in the reactor vessel and another part disposed outside of the reactor vessel, and through which refrigerant is passed, and that circulates the refrigerant exchanging heat with the thermal conductor; a turbine that is rotated by the refrigerant circulating through the refrigerant circuit; and a generator that is rotated integrally with the turbine.