A nuclear fission reactor comprising a core, a pool of coolant liquid, and a heat exchanger. The core comprises an array of hollow tubes which contain molten salts of fissile isotopes. The tube array is at least partly immersed in the pool of coolant liquid. The tube array comprises a critical region, where the density of the fissile isotopes during operation of the reactor is sufficient to cause a self-sustaining fission reaction. Heat transfer from the molten salts of fissile isotopes to the tubes is achieved by any one or more of natural convection of the molten salts, mechanical stirring of the molten salts, and oscillating fuel salt flow within the tubes. The molten salts of fissile isotopes are contained entirely within the tubes during operation of the reactor.

A practical molten salt fission reactor

PROBLEM TO BE SOLVED: To provide a fuel assembly and a nuclear reactor core which allow improvement in maintenance work and repair work of a nuclear power plant.SOLUTION: A fuel assembly to be loaded to a core of a fast breeder reactor has a plurality of fuel rods 1A. Each fuel rod 1A includes a liquid nuclear fuel material 2, a hermetically sealed cladding tube 3 made of stainless steel, and an inner tube 22 made of Hastelloy-N (R). The hermetically sealed inner tube 22 is disposed in the cladding tube 3 to cover all the inside surface of the cladding tube 3. The liquid nuclear fuel material 2 is filled in the inner tube 22. The liquid nuclear fuel material 2 comprises, for example, a fluoride molten salt containing Th-232 and U-233 and is made liquid during operation of the fast breeder reactor. An outside surface of the cladding tube 3 is in contact with a liquid metal as a coolant. Since TI-208 produced by neutron absorption reaction of Th-232 does not flow into the liquid metal, maintenance work and repair work of structure members (primary system piping, primary system pumps, etc.) of the fast breeder reactor are improved.

Fuel assembly and nuclear reactor core

To obtain a molten-salt nuclear fuel element that can be loaded in a conventional reactor core and that enables combustion and nuclear conversion of plutonium and radioactive waste A molten-salt fuel element provided with: an electrode device (3) for controlling the reduction and oxidation (REDOX) of the molten salt in a cylindrical molten salt fuel channel (8) having a molten salt as fuel, the electrode device (3) being installed in the upper part of a molten salt fuel cask (4) for accommodating the molten salt fuel channel (8), and the molten salt fuel channel (8) being installed in the molten salt fuel cask (4); a gas pressurization device for pressurizing and compressing a fission gas generated from the molten salt fuel channel, the gas pressurization device being installed in the upper part of the electrode device (3) for performing the REDOX control; and a gas plenum for accommodating the compressed gas, the gas plenum being installed in the upper portion the gas pressurization device

Molten salt nuclear fuel module

A molten salt reactor using liquid fuel is a highly secure nuclear reactor in which fuel damage, steam explosions, and the like do not occur. However, the fuel itself is moved in a primary system of the reactor, necessitating countermeasures against radiation in the primary system, and therefore there are problems with the ease of maintenance, an expansion of the radiation controlled area, and so on. In the present invention, a liquid fuel is enclosed in a fuel container and is thus used without being caused to circulate in the primary system, and therefore, fuel management can be done on the basis of individual fuel assemblies (6), resulting in easier management of radioactive substances, and the aforementioned problems accompanying the movement of the liquid fuel in the primary system (S1) can be solved. In the present invention, a freeze seal is used when the liquid fuel is enclosed in the fuel container, and accordingly, an increase in temperature in the event of an emergency would cause the freeze seal to melt allowing the liquid fuel (5) to be drained into a bottle (21) below, resulting in enhanced passive safety. In addition, a structure whereby molten salt fuel in the fuel container can be loaded into and removed from a core allows the output of power to be directly controlled with the amount of the fuel, resulting in enhanced load following capabilities.

Compact molten salt reactor

PROBLEM TO BE SOLVED: To solve the problem wherein the power generation efficiency of a nuclear reactor transferring heat produced from a nuclear fuel to a coolant through convective heat transfer is low because the coolant and the nuclear fuel are integrated and the temperature of the coolant is low. SOLUTION: The heat produced from the nuclear fuel is transferred to the coolant through radiant heat. The coolant is isolated from the nuclear fuel. Temperature of the coolant is set at a high temperature. Power generation efficiency and safety of the nuclear reactor are enhanced. COPYRIGHT: (C)2006,JPO&NCIPI

Radiant heat nuclear power generator

PURPOSE:To execute the retreatment of used fuel with compact equipment and simplified process by forming a low melting plutomium and/or uranium alloy fuel phase, low melting salt phase and gas plenum successively from below to above in each fuel element. CONSTITUTION:The low melting plutonium and/or uranium alloy fuel phases 3 which melt at the operating temp. of a reactor furnace, the low melting salt phases 4 and the gas plenums 5 are formed in this order successively from lower to upper layers in the respective fuel elements 1a of the reactor vessel in which a liquid metal is used as a coolant and is disposed with the plural fuel elements in the cores. The alloy fuel phases 3 are thereby burned in the molten state during the reactor operation. The fission gases generated at this time are collected in the gas plenums 5 and the fission products are partly transferred to the salt phases 4 in the molten state, by which the self-refining function is provided to the alloy fuel phases 3 in the fuel elements 1a.

Nakajima Ichiro

Papers

Self-refining molten metal fuel furnace