A PRACTICAL MOLTEN SALT FISSION REACTOR

• US 20160005497A1
• Filed: 02/19/2014
• Published: 01/07/2016
• Est. Priority Date: 02/25/2013
• Status: Active Grant

• Current Assignee: Ian Richard Scott
• Original Assignee: Ian Richard Scott
• Inventors: SCOTT, Ian Richard
• Granted Patent: US 10,043,594 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G21C 1/03 cooled by a coolant not essentially pressurised, e.g. pool-type reactors
• CPC Class Codes: G21C 1/22 using liquid or gaseous fuel
• CPC Class Codes: G21C 3/24 with fissile or breeder material in fluid form within a non-active casing
• CPC Class Codes: G21C 3/54 Fused salt, oxide or hydroxide compositions
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors

Abstract

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.

Claims

1. A nuclear fission reactor, the reactor comprising a core, a pool of coolant liquid, and a heat exchanger for extracting heat from the coolant liquid, wherein:

the core comprises an array of hollow fuel tubes, each containing molten salt of one or more fissile isotopes, the fuel tube array being at least partly immersed in the pool of coolant liquid, the fuel tube array comprising a critical region, where the density of the fissile isotopes during operation of the reactor is sufficient to cause a self-sustaining fission reaction;

wherein heat transfer from the molten salt in each fuel tube to the exterior of that tube is achieved by any one or more of;

natural convection of the molten salt;

mechanical stirring of the molten salt;

oscillating molten salt flow within the fuel tube; and

boiling of the molten salt within the fuel tube;

and wherein the molten salt of fissile isotopes is contained entirely within the fuel tubes during operation of the reactor.

2. A reactor according to claim 1, wherein each fuel tube comprise internal baffles configured to divide at least a portion of the tube into segments.

3. A reactor according to claim 2, wherein each segment has a height and diameter that are the same order of magnitude so as to facilitate convection within the segment.

4. A reactor according to claim 2, wherein the internal baffles are movable relative to the fuel tube so as to impart oscillatory forces to the molten salt within the tube.

5. A reactor according to claim 1, wherein each fuel tube has a diameter of at least 5 mm.

6. A reactor according to claim 1, wherein each tube is U shaped, the reactor being configured to generate oscillating fuel salt flow within the tube by applying an oscillating gas pressure to one or both ends of the tube.

7. A reactor according to claim 1, wherein one or more of the tubes is formed as a shallow helix.

8. A reactor according to claim 1, wherein an upper portion of each tube is non-linear so as to prevent neutrons passing directly up the tube and out of the reactor.

9. A reactor according to claim 1, wherein each tube comprises a temperature sensor configured to determine the temperature of the molten salt of fissile material by any one of:

properties of light emitted from the molten salt of fissile material;

an amount of expansion of the fissile material;

a resonant acoustic frequency of a gas column in the tube.

11. A reactor according to claim 1 wherein the coolant liquid contains a sufficient proportion of a neutron absorbing material to substantially shield a containing tank of the liquid from neutrons emitted by the core.

12. A reactor according to claim 1 wherein the coolant liquid is a molten metal salt contained within a single tank, and the circulation of the coolant liquid is driven by natural convection only.

13. A reactor according to claim 1 wherein the coolant liquid contains a fertile isotope which produces a bred fissile isotope under neutron flux

14. A reactor according to claim 13, wherein the reactor comprises a layer of molten metal in contact with the coolant liquid, the molten metal being such that the bred fissile isotope is soluble in the molten metal, the reactor further comprising a system for extracting the molten metal.

15. A reactor according to claim 14, and comprising a system for circulating the molten metal such that it is drawn from the layer of molten metal and reintroduced to the coolant liquid as a spray or a plurality of columns, wherein the molten metal is passed to the heat exchanger prior to being reintroduced.

16. A reactor according to claim 1, wherein the heat exchanger comprises an array of tubes within the coolant liquid, the tubes containing a liquid and/or gas which circulates through the tube array, wherein the liquid and/or gas is any of:

water;

steam;

water and steam;

helium;

carbon dioxide;

air;

nitrogen;

a molten metal or metal salt.

17. A reactor according to claim 1, wherein the fuel tubes are formed from any of:

a molybdenum alloy;

pure molybdenum;

a carbon composite; and

silicon carbide.

18. A reactor according to claim 1, wherein the core further comprises a neutron moderating material.

19. A reactor according to claim 17, wherein said neutron moderating material is provided in moderator tubes within the array of fuel tubes.

20. A reactor according to claim 1, wherein the number density of fuel tubes is reduced towards the centre of the array of fuel tubes.

21. A reactor according to claim 1, wherein the concentration of fissile and/or fertile isotopes within the fuel tubes is increased towards the outside of the array of fuel tubes.

22. A reactor according to claim 1, wherein the fuel tubes comprise or contain a metal having a reactivity with halogens intermediate between the fuel tube material and the fissile isotopes.

23. A reactor according to claim 1, wherein the molten salts of fissile isotopes comprise trihalides of the fissile isotopes.

10. (canceled)

24. A method of operating a nuclear fission reactor comprising a core, a pool of coolant liquid and a heat exchanger, the core comprising an array of hollow fuel tubes, each containing the molten salt of one or more fissile isotopes, the fuel tube array being at least partly immersed in the pool of coolant liquid and comprising a critical region, where the density of the fissile isotopes during operation of the reactor is sufficient to cause a self-sustaining fission reaction, the method comprising:

containing the molten salt entirely within the fuel tubes;

transferring heat from the molten salt in each fuel tube to the exterior of that tube and thus to the coolant using one or more of;

natural convection of the molten salt;

mechanical stirring of the molten salt;

oscillating molten salt flow within the fuel tube; and

boiling of the molten salt within the fuel tube; and

extracting heat from the coolant using the heat exchanger.