A system includes a containment vessel configured to prohibit a release of a coolant, and a reactor vessel mounted inside the containment vessel. An outer surface of the reactor vessel is exposed to below atmospheric pressure, wherein substantially all gases are evacuated from within the containment vessel.

A system includes a containment vessel configured to prohibit a release of a coolant, and a reactor vessel mounted inside the containment vessel. An outer surface of the reactor vessel is exposed to below atmospheric pressure, wherein substantially all gases are evacuated from within the containment vessel.

A control rod for a nuclear fuel assembly is described herein that includes a neutron absorbing material having a melting point greater than 1500 C. that does not form a eutectic with a melting point less than 1500 C., and may further include a cladding material having a melting point greater than 1500 C. The cladding material is selected from the group consisting of silicon carbide, zirconium, a zirconium alloy, tungsten, and molybdenum. The absorbing material is selected from the group consisting of Gd.sub.2O.sub.3, Ir, B.sub.4C, Re, and Hf. The metal cladding or the absorbing material may be coated with an anti-oxidation coating of Cr with or without a Nb intermediate layer.

Disclosed is a nuclear reactor, comprising: a canister, a nuclear reactor core housed inside of the canister, and a controlled temperature housing attached to the canister. The nuclear reactor core comprises a control drum and a shaft extending from the control drum and out of the nuclear reactor core. Heat generated by the nuclear reactor core enters the controlled temperature housing. The controlled temperature housing comprises a proximal end attached to the canister, a first internal plate spaced from and positioned distal to the proximal end, a second internal plate spaced from and positioned distal to the first internal plate, and a motor mounted to the second internal plate. The shaft enters the controlled temperature housing through the proximal end and extends to the motor. The controlled temperature housing is to passively maintain the motor at a temperature equal to or below a predetermined temperature threshold.

Disclosed is a nuclear reactor, comprising: a canister, a nuclear reactor core housed inside of the canister, and a controlled temperature housing attached to the canister. The nuclear reactor core comprises a control drum and a shaft extending from the control drum and out of the nuclear reactor core. Heat generated by the nuclear reactor core enters the controlled temperature housing. The controlled temperature housing comprises a proximal end attached to the canister, a first internal plate spaced from and positioned distal to the proximal end, a second internal plate spaced from and positioned distal to the first internal plate, and a motor mounted to the second internal plate. The shaft enters the controlled temperature housing through the proximal end and extends to the motor. The controlled temperature housing is to passively maintain the motor at a temperature equal to or below a predetermined temperature threshold.

One variation of a system includes: a nuclear reactor; a shield arranged about the nuclear reactor; a metallic coolant; and a set of melt seals. The nuclear reactor includes a pressure vessel and nuclear fuel arranged within a lower region of the pressure vessel. The metallic coolant includes a mixture of metals and is configured to: occupy a liquid state within an operating temperature range; occupy an interstitial volume between the nuclear reactor and the shield; and occupy the lower region of the pressure vessel encompassing the nuclear fuel. The set of melt seals are arranged on the pressure vessel and configured to open to enable transfer of a volume of the metallic coolant from the interstitial volume into the lower region of the pressure vessel in response to temperatures within the pressure vessel exceeding the operating temperature range.

The group of invention refers to the area of nuclear power engineering, particularly to auxiliary devices for nuclear power plants, namely to the devices for installation of the outer heat insulation of a nuclear reactor vessel, and can be used at nuclear plants for recovery annealing of welds and/or base metal of the VVER reactor pressure vessel. The task to be solved by the claimed group of inventions is to ensure the installation and disassembly of heat insulation of the outer surface of the VVER reactor pressure vessel in the confined space under the reactor and with the high level of ionizing radiation, as well as work performance in an automated mode, which excludes the exposure of personnel to ionizing radiation.

The technical result of the invention related to outer heat insulation of the nuclear reactor pressure vessel is the reduction of the temperature gradient through the thickness of the nuclear reactor vessel by heat insulation of the external reactor vessel surface, assurance of uniform physical properties for the reactor vessel metal and welds, and reduction of thermal impacts on the surrounding structures during recovery annealing of the welds and/or base metal of the VVER reactor vessel.

The technical result of the invention is provided by the fact that the external heat insulation of the nuclear reactor pressure vessel includes racks, supporting and heat insulation rings installed in series above each other on the upper support platforms of the racks and covering the nuclear reactor pressure vessel, with the racks evenly placed under the supporting and heat insulation rings on the floor of the space under reactor, each rack is provided with guide channels made on the upper part of the inner surface of the rack, and pivoted on the rack base, while the joint between the rack and the rack base is offset relative to the center of gravity of the rack with the possibility of deflection of the rack from the vertical position and its self-return to the vertical position, and the rack base is equipped with an adjustable screw support and has a support platform. Primarily supporting and heat insulation rings are made in the form of articulated sections of frame structure, made in the form of arched ring segments; heat insulation made of mullite-silica felt is fixed on the inner side of the frame of each heat insulation ring section; heat insulation blocks made in the form of triangular sheet piles of mullite-silica felt are additionally fixed on the upper surface of the upper heat insulation ring sections; support casings are made on the outer side of the frame of the support and heat insulation ring sections adjacent to the racks.

A system includes a containment vessel configured to prohibit a release of a coolant, and a reactor vessel mounted inside the containment vessel. An outer surface of the reactor vessel is exposed to below atmospheric pressure, wherein substantially all gases are evacuated from the containment vessel.

A system includes a load-following nuclear power generator including a nuclear reactor configured to generate variable amounts of electricity. The system also includes an electric drive and a propeller controlled by the electric drive.

A system includes a load-following nuclear power generator including a nuclear reactor configured to generate variable amounts of electricity. The system also includes an electric drive and a propeller controlled by the electric drive.