A nuclear fission power plant

Abstract

A nuclear fission power plant (10) comprising: a gas circuit (90) to circulate gas; a nuclear reactor core (20) comprising: a fuel system (30) and a moderator (35); the nuclear fission power plant further comprising a neutron reflector (70), a plurality of control drums (50), one or more control rods (60), and a containment vessel (40) substantially surrounding the nuclear reactor core and allowing gas in the gas circuit to flow through both the containment vessel and the core, and an open Brayton power system coupled to the gas circuit via a heat exchanger (92), the open Brayton power system comprising: a compressor (102); a turbine system (104); and a generator (108); the open Brayton power system being arranged such that the turbine system is configured to drive the compressor and the generator.

Description

2024PF002401A NUCLEAR FISSION POWER PLANTTECHNICAL FIELD

[0001] This disclosure relates to a nuclear fission power plant configured for use in a terrestrial environment and a kit of parts and method for a nuclear fission power plant configured for use in a terrestrial environment.BACKGROUND

[0002] It is desirable to have a reliable and low-carbon power source capable of deployment in a terrestrial environment. Terrestrial environments may include deserts, tundra, temperate climates, tropical rainforests, the Arctic, Antarctica, etc. Solar panels are often used as a means to generate electricity in terrestrial environments. However, their power density is low and they are limited to applications in sunlight. This is a particular problem for expeditions where a facility could be in darkness or in shadow for prolonged periods of time, e.g. a facility located in or substantially towards the Antarctic circle during the winter solstice, or a facility located beneath a tree canopy in a forest or jungle. The low power density of solar panels further limits their application. In particular, a facility in a terrestrial environment may have a high power requirement for which solar panels are not suited. Similarly, wind turbines may not be effective in locations with too low or too high an average wind speed for effective use of the turbine. Wind turbines also suffer from increased complexity in transportation and logistics, especially with regards to transporting the turbine blades, which may make it difficult to rapidly deploy a wind turbine to a terrestrial environment. On the other hand, diesel or gas generators are high-carbon energy sources, emit greenhouse gasses, and may be highly noise polluting.

[0003] The high-power density of a nuclear fission power plant and its ability to generate electricity independently from environmental conditions (e.g. sunlight or wind) make nuclear fission power plants an attractive option for use in terrestrial environments. However, it is desirable for a nuclear fission power plant to withstand harsh environmental conditions, require minimal maintenance, and be sufficiently robust to withstand damage in transit to a terrestrial environment. Weight and size are also issues as any power plant would likely need to fit within the confines of a container or containers in a transport vessel(s) capable of journeying to possibly remote and harsh environments.

[0004] The present disclosure seeks to address these issues.2024PF002402SUMMARY

[0005] According to a first aspect there is provided a nuclear fission power plant configured for use in a terrestrial environment, the nuclear fission power plant comprising: a gas circuit comprising: a first pump; a first passage through a heat exchanger; and a containment vessel, wherein the containment vessel contains at least: a neutron reflector comprising graphite disposed around a periphery of a nuclear reactor core; and a plurality of control drums disposed around the periphery of the nuclear reactor core; wherein the nuclear reactor core comprises: a fuel system comprising TRISO fuel; a moderator comprising graphite; and at least one core inlet and at least one core outlet; the containment vessel further comprising a containment vessel inlet and a containment vessel outlet, the containment vessel inlet and containment vessel outlet being configured such that gas circulating around the gas circuit flows from the containment vessel inlet towards the nuclear reactor core, into the nuclear reactor core via the at least one core inlet, out of the nuclear reactor core via the at least one core outlet, and towards the containment vessel outlet; the nuclear fission power plant further comprising one or more control rods, each of the one or more control rods being configured to be selectively inserted into one or more corresponding void(s) in the nuclear reactor core; and an open Brayton cycle power system coupled to the gas circuit via the heat exchanger, the open Brayton power system comprising: a compressor; a turbine system; and a generator; the open Brayton power system being arranged such that air can flow through the compressor, the heat exchanger, and the turbine system, wherein the heat exchanger is configured to permit heat in the gas flowing through the gas circuit to be transferred to the compressed air from the compressor, and the turbine system is configured to drive the compressor and the generator.

[0006] The fuel system of the nuclear fission power plant may comprise High Assay Low Enriched Uranium (HALEU).

[0007] The fuel system of the nuclear fission power plant may be enriched to substantially 19.75% uranium-235.

[0008] The TRISO fuel may comprise uranium-oxycarbide.

[0009] The TRISO particle fuel particle may comprise a uranium, carbon, and oxygen fuel kernel.

[0010] The moderator of the nuclear fission power plant may comprise zirconium hydride.2024PF002403

[0011] The neutron reflector of the nuclear fission power plant may comprise aluminium oxide.

[0012] The nuclear fission power plant may further comprise a neutron shield disposed around a periphery of the neutron reflector. The neutron shield may comprise boron carbide.

[0013] The control drums may be a primary form of control to control a reactivity level of the nuclear reactor core, and may be used for fine control of the reactivity level.

[0014] The one or more control rods may be secondary form of control to control a reactivity level of the nuclear reactor core, and may be used for coarse control of the reactivity level.

[0015] According to a second aspect there is provided a kit of parts for a nuclear fission power plant configured for use in a terrestrial environment, the kit of parts being configured at least partially for assembly at the terrestrial environment and comprising: a nuclear reactor core; a containment vessel; a plurality of control drums; one or more control rods; a neutron reflector; a heat exchanger; a first pump; and an open Brayton cycle power system; the kit of parts being configured to be assembled to form: a gas circuit comprising: the first pump; a first passage through the heat exchanger; and the containment vessel; wherein the containment vessel is configured to contain at least: the neutron reflector, the neutron reflector comprising graphite disposed around a periphery of the nuclear reactor core; the plurality of control drums, configured to be disposed around the periphery of the nuclear reactor core; and the nuclear reactor core, the nuclear reactor core comprising: a moderator comprising graphite; at least one core inlet and at least one core outlet; one or more voids configured to receive the one or more control rods, the one or more control rods each being configured to be selectively insertable into a corresponding void in the nuclear reactor core; the nuclear reactor core being configured to accept a fuel system comprising TRISO fuel; the containment vessel further comprising a containment vessel inlet and a containment vessel outlet, the containment vessel inlet and containment vessel outlet being configured such that when assembled, gas can circulate around the gas circuit, flowing from the containment vessel inlet towards the nuclear reactor core, into the nuclear reactor core via the at least one core inlet, out of the nuclear reactor core via the at least one core outlet, and towards the containment vessel outlet; the open Brayton cycle power system being configured to be coupled to the gas circuit via the heat exchanger, the open Brayton power system comprising: a compressor; a turbine system; and a generator; the open Brayton power system being arranged such that when assembled, air can flow through the compressor, the heat exchanger, and the turbine system, wherein the heat exchanger is configured to permit heat in the gas flowing through the gas circuit to be2024PF002404 transferred to the air from the compressor, and the turbine system is configured to drive the compressor and the generator.

[0016] The kit of parts may further comprise a neutron shield configured to be disposed around a periphery of the neutron reflector.

[0017] According to a third aspect, there is provided a method for a nuclear fission power plant configured for use in a terrestrial environment, the method comprising controlling the nuclear fission power plant to: generate heat with a nuclear reactor core, the nuclear reactor core comprising a fuel system, a moderator, at least one core outlet, and at least one core inlet, wherein: a neutron reflector is disposed around a periphery of the nuclear reactor core; a plurality of rotatable control drums are disposed around the periphery of the nuclear reactor core; one or more control rods are configured to be selectively inserted into one or more corresponding voids in the nuclear reactor core; and a containment vessel is arranged to substantially surround the nuclear reactor core, the containment vessel comprising a containment vessel inlet and a containment vessel outlet, and being configured to define a flow path between the containment vessel inlet and the containment vessel outlet, such that gas following the flow path flows from the containment vessel inlet towards the nuclear reactor core, into the nuclear reactor core via the at least one core inlet, out of the nuclear reactor core via the at least one core outlet, and towards the containment vessel outlet; circulate gas around a gas circuit, including delivering the gas to the containment vessel inlet to be heated by the nuclear reactor core, and extracting the gas from the containment vessel outlet; and generate electricity with an open Brayton power system coupled to the gas circuit via a heat exchanger, the open Brayton power system comprising a compressor, a turbine system, and a generator, the open Brayton power system being arranged such that air flows through the compressor, the heat exchanger, and the at least one turbine, wherein the heat exchanger is configured to permit heat in the gas flowing through the gas circuit to be transferred to the compressed air from the compressor, and the at least one turbine is configured to drive the compressor and the generator.

[0018] The skilled person will appreciate that except where mutually exclusive, a feature described in relation to any one of the above aspects may be applied mutatis mutandis to any other aspect. Furthermore, except where mutually exclusive any feature described herein may be applied to any aspect and / or combined with any other feature described herein.2024PF002405BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Embodiments will now be described by way of example only with reference to the accompanying drawings, in which:

[0020] FIG. 1 is a schematic diagram showing an arrangement of an example nuclear fission power plant configured for use in a terrestrial environment;

[0021] FIG. 2 is a schematic diagram showing an example arrangement of control drums with respect to a nuclear reactor core;

[0022] FIG. 3 is a schematic diagram showing an example actuator arrangement for control drums;

[0023] FIG. 4 is a schematic diagram showing another example actuator arrangement for control drums;

[0024] FIG. 5 is a schematic diagram showing an example neutron shielding arrangement; and

[0025] FIG. 6 is a flowchart depicting a method for a nuclear fission power plant configured for use in a terrestrial environment.DETAILED DESCRIPTION

[0026] The present disclosure relates to a nuclear fission power plant configured for use in a terrestrial environment. The nuclear fission power plant is configured to be sufficiently robust, low-weight, deployable, and rugged to be transported to and used anywhere on the Earth’s surface, including remote and harsh environments such as desert regions, tropical rainforests, tundra, etc. Transportation / deployment to such environments may use any of ground / land-based vehicles (e.g. trucks, trains, etc.), aircraft (e.g. helicopters, airplanes, etc.), watercraft (e.g. boats, ships, etc.), or any other form of transportation. The nuclear fission power plant may be fully assembled prior to transportation or may be at least partially assembled before transportation. Alternatively, the nuclear fission power plant may be configured to be assembled where it is intended to be operated. For example, the nuclear fission power plant may be transported in modular components or in sub-assemblies. Each module or sub-assembly may be transported, and the nuclear fission power plant may subsequently be assembled.2024PF002406

[0027] The nuclear fission power plant may be a micro- reactor. The micro-reactor may have a power output in the range of 1 - 5MW. The nuclear fission power plant may be readily transportable, e.g. in a standard shipping container, or in a plurality of shipping containers containing distinct modules / sub-assemblies of the nuclear fission power plant.

[0028] Referring to FIG. 1 , the nuclear fission power plant 10 comprises a gas circuit 90 configured to allow passage of a gas. The gas circuit 90 comprises a first passage 142 through a heat exchanger 92 and a first pump 94. The first pump 94 may be operated to pump gas around the gas circuit. The gas circuit 90 further comprises a containment vessel 40. The gas circuit 90 is configured such that gas being pumped around the gas circuit 90 enters the containment vessel 40 via a containment vessel inlet 42. The gas circuit 90 is further configured such that gas being pumped around the gas circuit 90 exits the containment vessel 40 via a containment vessel outlet 44.

[0029] As depicted, within the containment vessel 40 there is a nuclear reactor core 20. The nuclear reactor core 20 comprises a fuel system 30. The fuel system 30 may comprise High Assay Low Enriched Uranium (HALEU), e.g., with the concentration of the fissile isotope uranium-235 (U-235) being between 5% and 20% of the mass of uranium. In particular, fuel of the fuel system 30 may be enriched to substantially 19.75% uranium-235. This level of enrichment allows for better energy density whilst maintaining a safe level of enrichment.

[0030] The fuel system 30 comprises Tri-structural Isotropic (TRISO) particle fuel. Each TRISO particle fuel may comprise a uranium, carbon and oxygen fuel kernel, such as a mixture of UO2 and UC. The TRISO particle fuel may comprise uranium oxycarbide (UCO). The TRISO fuel system may undergo fission from neutrons that have undergone moderation (slowing down). The TRISO fuel may be coated with layers of carbon and a layer of siliconcarbide (SiC). The carbon and SiC-coated layers prevent the release of fission isotopes into the environment, thereby improving an overall safety of the nuclear fission power plant 10. These small, coated particles (around the size of a poppy seed) may then be manufactured into compacts, with a matrix material holding the particles together. The matrix holding the particles together may be substantially cylindrical and may be provided in pellet form. The pellets may be clad, e.g. in one or more layers of ceramic or one or more layers of metal or any combination of ceramic and metal layers.

[0031] The nuclear reactor core 20 is moderated and comprises a moderator 35. The moderator 35 is situated within the nuclear reactor core 20 and may be interspersed throughout the nuclear reactor core, i.e. interspersed between regions containing fuel. Whilst in the example of FIG. 1 the moderator 35 is shown in distinct blocks (indicated with the2024PF002407 diagonal hatching) between regions of fuel, it is to be understood that the moderator may also, or instead, surround or envelope the fuel. For example, the moderator may take the form of a monolith (the monolith being the structure in which the fuel is contained - not shown in FIG. 1) in which the fuel is encased.

[0032] The moderator 35 serves to slow down neutrons travelling within the nuclear reactor core 10, thus increasing their cross-section of interaction with uranium atoms within the core, leading to an increased number of fission events. Thus, the moderator improves the neutron economy of the nuclear reactor core 20, which is important given that the nuclear fission power plant 10 may be located in a remote location, and therefore challenging to refuel on a regular basis. The moderator comprises graphite. Graphite may be a good selection for deployable applications as it has excellent thermal properties and good mechanical strength at high temperatures, as well as being relatively easy to machine and manufacture into a desired form.

[0033] The nuclear reactor core 20 is gas-cooled. Specifically, the nuclear reactor core is cooled by gas flowing around the gas circuit. The nuclear reactor core 20 comprises at least one core inlet 46 and at least one core outlet 48. Heat may therefore be extracted from the nuclear reactor core 20 by virtue of gas flowing within and through the nuclear reactor core 20. Specifically, heat energy is transferred from one or more components of the nuclear reactor core to the gas flowing within the nuclear reactor core as the gas passes through nuclear reactor core 20. This heat energy is then extracted from the gas at a later stage in the gas circuit (as shall be explained), thus cooling the gas, prior to the gas returning back around the gas circuit to the nuclear reactor core, where it is reheated. The gas circuit 90 is configured such that the gas enters the nuclear reactor core 20 via the at least one core inlet 46 and exits the nuclear reactor core 20 via the at least one core outlet 48. The gas may be helium, heliumxenon (a mixture of helium and xenon), nitrogen, hydrogen, or any other appropriate cooling gas. The gas cooling system may allow higher core temperatures to be reached, where coolant evaporation issues (which can afflict pressurised water reactors) are eliminated. This, in turn, may allow for a greater thermodynamic efficiency of the nuclear fission power plant by creating a greater temperature difference between the reactor core 20 and heat sink.

[0034] The nuclear fission power plant 10 further comprises a plurality of control drums 50. The control drums 50 may be controlled to vary the degree to which the control drums 50 absorb or reflect neutrons from the nuclear reactor core 20, and thereby control reactivity levels in the nuclear reactor core 20. The control drums 50 are disposed within the containment vessel 40, around the periphery of the nuclear reactor core 20. In the example of2024PF002408FIG. 1 , the control drums are shown in cavities within the neutron reflector 70. Whilst only two control drums 50 are visible (in sectional view) in FIG. 1 , it is to be understood that more control drums could be arranged around the periphery of the nuclear reactor core, an example of such an arrangement being shown in FIG. 2.

[0035] The control drums 50 are configured to be rotated by one or more first actuators 52 (these have been omitted in FIG. 2 for clarity). Rotation of the drums by the one or more first actuators 52 may vary whether the control drums 50 absorb or reflect neutrons from the nuclear reactor core 20. The first actuator(s) 52 may be controlled by a suitable first controller 54, which may receive data from one or more sensors. In the example of FIG. 1 , the first actuators 52 are controlled by a first controller 54. The first controller 54 may be in communication with any suitable reactivity sensor system (not shown) of the nuclear fission power plant 10, which may determine (for example) a rate of fission in the nuclear reactor core 20. Each control drum may comprise a neutron-reflecting material 51 (e.g. graphite or aluminium oxide) and may further comprise a neutron-absorbing material 53 (e.g. boron carbide). The neutron-absorbing material 53 may be disposed over at least a portion of an outer circumference of the drum. To promote reactivity, the control drums may be positioned such that more of the reflecting material 51 is facing toward the core, thereby directing more neutrons back into the nuclear reactor core. To slow down reactivity, each control drum cylinder may be rotated so that more of the neutron-absorbing material 53 is facing toward the core, thereby absorbing more neutrons to slow down the nuclear reactor. In this way, reactivity levels of the nuclear reactor core 20 may be controlled and the control drums may provide the primary form of reactivity control. The control drums 50 may be used for fine control, such as during a normal operating mode of the nuclear fission power plant 10. The control drums 50 are advantageously compact and sufficiently robust for transportation.

[0036] Two or more independent first actuators 52 may be provided for redundancy. For example, a first actuator may be provided at each end of a control drum, as shown in the example of FIG. 3. In another example arrangement shown in FIG. 4, the control drums may be arranged in two or more independent sets of control drums with each set having its own first actuator 52. The control drums within a particular set may alternate with control drums from another set. For example, there may be two independent sets of control drums interspersed with one another about the circumference of the nuclear reactor core 20. Although only one first controller 54 is shown in the example of FIG. 1 , there may be two or more independent first controllers 54. As shown in the example of FIG. 4, a first controller 54 may be provided for each set of rotatable drums. Therefore, to achieve a desired level of reactivity in the nuclear reactor core 20, the first controller(s) 54 may operate first actuators2024PF00240952 to either cause each control drum of the nuclear fission power plant 10 to rotate, or cause a set of control drums of the nuclear fission power plant 10 to rotate, or cause individual control drums of the nuclear fission power plant 10 to rotate.

[0037] Returning to FIG. 1 , the nuclear fission power plant 10 further comprises one or more control rods 60. The one or more control rods 60 are configured to be selectively inserted into corresponding voids 65 within the nuclear reactor core. This may occur by way of one or more second actuator(s) 62 wherein the one or more second actuator(s) 62 are coupled or otherwise in communication with one or more control rods 60. The one or more second actuator(s) 62 may be in communication with a second control system 63. The one or more control rods maybe be contained within the containment vessel 40, or may be configured to be inserted into the nuclear reactor core 20 through the containment vessel 40.

[0038] The control rods are made of a material or materials that can absorb neutrons within the nuclear reactor core 20, in order to prevent the neutrons from instigating fission events in the fuel atoms. As such, the degree to which the control rods are inserted into the nuclear reactor core determines how many neutrons the control rods can absorb, and therefore their effect on the rate of fission events occurring within the nuclear reactor core. The one or more control rod(s) may comprise one of boron carbide or tantalum.

[0039] The one or more control rods 60 may be used for coarse control, such as in an emergency or shut-down mode of the nuclear fission power plant 10. In the example nuclear fission power plant of FIG. 1 , the one or more control rod(s) may be inserted quickly into the nuclear reactor core 20 in the event of an emergency. An emergency event may be determined by a suitable reactivity sensor system (not shown) of the nuclear fission power plant 10.

[0040] Within the containment vessel 40 there is a neutron reflector 70 disposed around the nuclear reactor core 20. The neutron reflector 70 is configured to reflect neutrons back towards the core. The neutron reflector 70 may at least partially surround the nuclear reactor core 20. In particular, the neutron reflector 70 may surround or substantially surround the nuclear reactor core. For instance, the neutron reflector may be disposed around a periphery of the nuclear reactor core 20. The neutron reflector 70 may improve the efficiency of the nuclear fission power plant 10, as neutrons which have not been reflected by a primary neutronic control element may be reflected by the neutron reflector 70. The neutron reflector 70 may comprise elongate cavities. Each elongate cavity may be configured to receive a control drum 50. In this way, the control drums may be disposed around a periphery of the nuclear reactor core 20. The neutron reflector 70 may further comprise one or more control rod through holes to permit the control rods to be inserted into the one or more voids 65 of the2024PF0024010 nuclear reactor core 20. In addition, a plurality of channels may be formed in the neutron reflector 70. For example, the at least one core inlet 46 and the at least one core outlet 48 may be formed by virtue of a plurality of channels formed in the neutron reflector 70. The neutron reflector 70 comprises graphite, which, as stated previously, has excellent thermal properties and good mechanical strength at high temperatures, as well as being relatively easy to machine and manufacture into a desired form.

[0041] The containment vessel 40 defines a section of the gas flow path (see for example block arrows in FIG. 1) between the containment vessel inlet 42 and the containment vessel outlet 44. Accordingly, gas may flow through the containment vessel 40 in a predetermined manner. In this way, gas following the flow path flows from the containment vessel inlet 42 towards the nuclear reactor core 20. The flow path may direct the flow of the gas from the containment vessel inlet 42, through one or more channels formed in the neutron reflector 70 to the at least one core inlet 46. The gas may then flow into the nuclear reactor core 20 via the at least one core inlet 46. The gas may then flow through the nuclear reactor core 20, thereby forcing the gas to flow over, and absorb heat energy from, components within the nuclear reactor core 20. The gas (which has now been heated by the components within the nuclear reactor core) may subsequently flow out of the nuclear reactor core 20 via the at least one core outlet 48. The flow path may direct the flow of the gas from the at least one core outlet 48 to the containment vessel outlet 44. The gas may then exit the containment vessel 40 via the containment vessel outlet 44. In this way the nuclear reactor core is cooled by the gas flow, in that heat energy is transferred from the components of the nuclear reactor core to the gas as it flows through the nuclear reactor core, and extracted from the nuclear reactor core with the gas as the gas exits the nuclear reactor core.

[0042] With reference to FIG. 5, the nuclear fission power plant 10 may further comprise a neutron shield 80 disposed around the nuclear reactor core 20. The neutron shield 80 is configured to substantially reduce a likelihood of neutrons escaping from the nuclear fission power plant 10 and into the surrounding environment. The neutron shield 80 may at least partially surround the containment vessel 40. In particular, the neutron shield 80 may surround or substantially surround the containment vessel 40. For instance, the neutron shield 80 may be disposed around a periphery of the containment vessel 40. The neutron shield 80 may thus improve the safety of the nuclear fission power plant 10, as neutrons which have not been absorbed or reflected by the control drums, or reflected by the neutron reflector 70, may be absorbed by the neutron shield 80. The neutron shield 80 may be formed from boron carbide, or any other suitable neutron-absorbing material.2024PF0024011

[0043] The neutron shield 80 and the containment vessel 40 may comprise primary through-holes. The number and location of primary through-holes formed in the neutron shield 80 and the containment vessel 40 may correspond with the number and location of elongate cavities formed in the neutron reflector 70. A control drum 50 may thus be inserted into a corresponding elongate cavity of the neutron reflector 70 through a primary through-hole. Additionally or alternatively, the primary through-holes may allow e.g. cables, shafts, actuation systems, sensors, etc. to couple a first actuator 52 to a corresponding control drum 50. The neutron shield 80 and the containment vessel 40 may further comprise one or more secondary through-holes. The one or more secondary through-holes may correspond with the one or more control rod through-holes of the neutron reflector 70, such as to permit one or more control rods to be inserted into corresponding voids 65 of the nuclear reactor core 20. The neutron shield 80 may further comprise an outlet through-hole. The outlet through-hole formed in the neutron shield 80 may correspond with the containment vessel outlet 44. As such, cooling gas following the flow path defined by the containment vessel 40 may flow out of the containment vessel 40 and be received by e.g. a heat exchanging system.

[0044] Referring back to FIG. 1 , the gas, having absorbed heat energy from the nuclear reactor core, flows to and through a first passage 142 of the heat exchanger 92. The heat exchanger 92 is configured to transfer heat from the gas within the gas circuit 90 to the working fluid of an open Brayton cycle power system 130 which is flowing through the second passage 144 of the heat exchanger 92. It is to be understood that the terms “first passage” and “second passage” are not to be considered limiting to a single tube or route as indicated by the dotted and dashed lines of FIG. 1 , but rather are to also include any arrangement of two or more separated fluid flow paths which allow for the transfer of heat energy from the fluid in the gas circuit to the working fluid of the power conversion system without the two fluids coming in to contact or mixing. For example, the first 142 and second 144 passages within the heat exchanger may comprise a number of channels or branches which are intertwined with one another and divided by thermally conductive material so as to allow heat energy to flow via at least conduction from the gas within the gas circuit 90 to the working fluid of the open Brayton cycle power system 130.

[0045] The open Brayton cycle power system 130 comprises a compressor 102, a recuperator 120, a turbine system 104, and a generator 108. A fluid duct 110, such as an air duct, may fluidically couple the compressor 102 to the second passage 144 of the heat exchanger 92, and the second passage of the heat exchanger 92 to the turbine system 104. The turbine system 104 may comprise more than one turbine, in which case the plurality of turbines may also be connected to the fluid duct 110. The fluid duct 110 will have an intake2024PF0024012 configured to permit air from the environment into the compressor 102. The air, once compressed by the compressor, will then flow into a recuperator 120, where it can be heated by air exiting the turbine system 104. The air, now compressed and heated, will enter the heat exchanger 92. The heat exchanger 92 is configured to transfer heat from the gas of the gas circuit 90 to the air of the open Brayton cycle power system 130, so that the air is hot and compressed. The hot compressed air will subsequently flow into the turbine system 104. The turbine system 104 may be mechanically coupled to the compressor 102, e.g. via a shaft, and thus the turbine system 104, being driven by the air, may drive the compressor 102. The turbine system 104 is coupled to the generator 108, and thus drives the generator, to generate electrical power. The electrical power may be distributed via a power distribution network 114 to users. The air, following the fluid duct 110, therefore passes through the compressor 102, the recuperator 120, the heat exchanger 92, and the turbine system 104, before being exhausted back into the environment via an exhaust of the fluid duct 110. The air released back into the environment may subsequently act as a heatsink, thereby improving a thermodynamic efficiency of the open Brayton cycle power system 130.

[0046] Although not depicted, it is envisaged that the nuclear fission power plant 10 may be transported in distinct sub-assemblies. Each sub-assembly may be loaded into separate shipping containers, or into the same container, and may be assembled ‘in-situ’ at the terrestrial location, e.g. where power is required. As an example, a first sub-assembly may comprise the nuclear reactor core 20, the control drums 50, the control rods 60, the neutron reflector 70, the containment vessel 40, and the neutron shield 80. A second sub-assembly may comprise the first pump 94, the heat exchanger 92, and any further interconnecting piping of the gas circuit 90. A third sub-assembly may comprise the open Brayton cycle power system 130. A fourth sub-assembly may comprise the at least one first controller 54, and any first actuators 52 of the control drums and second actuators 62 of the control rods 60. This is but one example, it will be understood that other sub-assemblies are possible, and that the configuration of sub-assemblies may be adapted to best suit the means of transport. For example, first actuators 52 of the control drums 50 and second actuators 62 of the control rods 60 may be assembled into the first sub-assembly instead of being separately transported in the fourth sub-assembly. It is also possible for the nuclear fission power plant 10 to be completely assembled, loaded onto a container, and transported to the appropriate terrestrial location.

[0047] Although not depicted, it is envisaged that the nuclear fission power plant 10 may comprise at least one further gas circuit similar to gas circuit 90. The further gas circuit may be configured to transfer heat from gas flowing through the further gas circuit to the2024PF0024013 working fluid of the open Brayton cycle power system 130 via the heat exchanger 92 or a further heat exchanger. The further gas circuit may have a further pump for circulating a gas in the further gas circuit. The further gas circuit may effectively be parallel to the gas circuit 90 and may improve the robustness of the nuclear fission power plant 10 by providing redundancy in the event of one of the gas circuits failing.

[0048] Although not depicted, it is envisaged that the nuclear fission power plant 10 may comprise at least one further open Brayton cycle power system 130 (the open Brayton cycle power system being as described above). The further open Brayton power system may be configured to absorb heat from the working fluid of the gas circuit 90 or further gas circuit. The further open Brayton power system may therefore be coupled to the heat exchanger 92 or to a further heat exchanger. The further open Brayton power system may effectively be parallel to the open Brayton power system and may improve the robustness of the nuclear fission power plant 10 by providing redundancy in the event of one of the open Brayton power systems failing. The open Brayton cycle power system or further open Brayton cycle power system may comprise a second pump (not shown). The second pump may be useful in establishing the flow of air through the open Brayton cycle power system or further open Brayton cycle power system at startup of the nuclear fission power plant.

[0049] The present disclosure also relates to a kit of parts for the nuclear fission power plant 10. The kit of parts may comprise at least some of the above-described components. The kit of parts may be configured for placement within at least one container, such as a standard shipping container to be loaded onto a ship or a truck. The kit of parts may also be configured at least partially for assembly at the desired terrestrial deployment location. Once deployed in the terrestrial environment, the kit of parts may automatically assemble, or may be assembled with the assistance of a robot or any other operative.

[0050] With reference to FIG. 6, the present disclosure also relates to a method 200 for the nuclear fission power plant 10. The method 200 comprises controlling the nuclear fission power plant 10. The control of the nuclear fission power plant 10 may be at least partially carried out remotely. For example, the nuclear fission power plant 10 may be controlled from a control facility that is located remote to the location of the nuclear fission power plant 10. Alternatively, control of the nuclear fission power plant 10 may be carried out locally (i.e., at the location of the nuclear fission power plant 10).

[0051] The method 200 controls the nuclear fission power plant 10 such that in a first action 210, the nuclear fission power plant 10 generates heat with the nuclear reactor core 20. The nuclear reactor core comprises a fuel system, a moderator, at least one core outlet, and2024PF0024014 at least one core inlet. I addition, a neutron reflector is disposed around a periphery of the nuclear reactor core, a plurality of rotatable control drums are disposed around the periphery of the nuclear reactor core, and one or more control rods are configured to be selectively inserted into one or more corresponding voids in the nuclear reactor core. Furthermore, a containment vessel is arranged to substantially surround the nuclear reactor core, the containment vessel comprising a containment vessel inlet and a containment vessel outlet, and being configured to define a flow path between the containment vessel inlet and the containment vessel outlet, such that gas following the flow path flows from the containment vessel inlet towards the nuclear reactor core, into the nuclear reactor core via the at least one core inlet, out of the nuclear reactor core via the at least one core outlet, and towards the containment vessel outlet.

[0052] In a second action 220, gas is circulated around a gas circuit, the circulation including delivering the gas to the containment vessel inlet to be heated by the nuclear reactor core. In a third action 230, gas heated by the nuclear reactor core is extracted from the containment vessel outlet. In a fourth action 240, heat energy in the gas flowing through the gas circuit is transferred to air in an open Brayton power system via a heat exchanger. In a fifth action 250, air flows through the compressor, the heat exchanger, and the at least one turbine of the open Brayton power system. In a sixth action 260, the at least one turbine drives the compressor and the generator to generate electricity.

[0053] The present disclosure advantageously provides a very efficient nuclear power reactor plant with a high power-to-weight ratio. Using gas as the coolant in conjunction with TRISO fuel allows for the nuclear reactor core to reach much higher temperatures than other fuel forms and cooling methods. This is at least partly because the TRISO structure makes the fuel resilient to high temperatures and a gaseous coolant cannot change state at high temperatures in the way a liquid coolant can. This in turn can improve thermodynamic efficiency by providing a greater temperature gradient across the system.

[0054] A further advantage of the present disclosure is that it is particularly rugged and effective at retaining nuclear isotopes. This is due to the TRISO fuel system securely containing fission isotopes within a coated shell. Although the TRISO fuel form may have a lower fissile density, this is countered by the reflector and the moderator, which make better use of the available neutrons.

[0055] Safety of the nuclear fission power plant is improved by reducing a likelihood of neutrons and radioisotopes from being released into the environment. This is at least partly achieved by the neutron shield, which may absorb any neutrons that are not reflected by the2024PF0024015 neutron reflector. The rotatable drums provided, in combination with the one or more control rods, enables a controller or controllers to exert both fine and coarse control over the rate of fission in the core of the reactor. This further enhances a safety of the nuclear fission power plant.

[0056] It is further noted that the open Brayton cycle power system generator provides excellent power to weight performance when compared to other power conversion technologies. The open Brayton cycle power system is configured to use air from the surrounding environment as the working fluid of the system, and to use the air from the environment as the heat sink. A nuclear fission power plant that uses a steam Rankine cycle is confined to operating in environments with a water source. On the other hand, the nuclear fission power plant of the present disclosure may be deployed even to environments with no nearby water source, such as dry and arid desert environments like the Australian outback. This improves a robustness and versatility of the nuclear fission power plant, as it may safely function in almost all terrestrial environments.

[0057] A transportability and utility of the nuclear fission power plant is improved through the ability to either transport the nuclear fission power plant in distinct sub-assemblies, or to transport an ‘already’ assembled nuclear fission power plant. As such, if transport constraints (e.g. regulations) demand smaller shipping containers, this may be accommodated by transporting the nuclear fission power plant in sub-assemblies configured to be easily assembled at the environment. Where no such constraints exist, the nuclear fission power plant may be fully or substantially assembled (e.g. at a factory) before being transported to the environment, thereby reducing a complexity for an end operative.

[0058] Various examples have been described, each of which feature various combinations of features. It will be appreciated by those skilled in the art that, except where clearly mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and subcombinations of one or more features described herein.

Claims

2024PF0024016CLAIMS1. A nuclear fission power plant configured for use in a terrestrial environment, the nuclear fission power plant comprising: a gas circuit comprising: a first pump; a first passage through a heat exchanger; and a containment vessel, wherein the containment vessel contains at least: a neutron reflector comprising graphite disposed around a periphery of a nuclear reactor core; and a plurality of control drums disposed around the periphery of the nuclear reactor core; wherein the nuclear reactor core comprises: a fuel system comprising TRISO fuel; a moderator comprising graphite; and at least one core inlet and at least one core outlet; the containment vessel further comprising a containment vessel inlet and a containment vessel outlet, the containment vessel inlet and containment vessel outlet being configured such that gas circulating around the gas circuit flows from the containment vessel inlet towards the nuclear reactor core, into the nuclear reactor core via the at least one core inlet, out of the nuclear reactor core via the at least one core outlet, and towards the containment vessel outlet; the nuclear fission power plant further comprising one or more control rods, each of the one or more control rods being configured to be selectively inserted into one or more corresponding void(s) in the nuclear reactor core; and an open Brayton cycle power system coupled to the gas circuit via the heat exchanger, the open Brayton power system comprising: a compressor; a turbine system; and a generator; the open Brayton power system being arranged such that air can flow through the compressor, the heat exchanger, and the turbine system, wherein the heat exchanger is configured to permit heat in the gas flowing through the gas circuit to be transferred to the compressed air from the compressor, and the turbine system is configured to drive the compressor and the generator.2024PF00240172. The nuclear fission power plant of claim 1 , wherein the fuel system comprises High Assay Low Enriched Uranium (HALEU).

3. The nuclear fission power plant of claim 1 or 2, wherein the fuel system is enriched to substantially 19.75% uranium-235.

4. The nuclear fission power plant of any of the preceding claims, wherein the TRISO fuel comprises uranium-oxycarbide.

5. The nuclear fission power plant of claim 4, wherein the TRISO particle fuel comprises a uranium, carbon, and oxygen fuel kernel.

6. The nuclear fission power plant of any preceding claim, wherein the moderator comprises zirconium hydride.

7. The nuclear fission power plant of any preceding claim, wherein the neutron reflector comprises aluminium oxide.

8. The nuclear fission power plant of any preceding claim, further comprising a neutron shield disposed around a periphery of the neutron reflector.

9. The nuclear fission power plant of any of the preceding claims, wherein the control drums are a primary form of control to control a reactivity level of the nuclear reactor core, and are used for fine control of the reactivity level.

10. The nuclear fission power plant of any of the preceding claims, wherein the one or more control rods are a secondary form of control to control a reactivity level of the nuclear reactor core, and are used for coarse control of the reactivity level.

11. The nuclear fission power plant of claim 8, wherein the neutron shield comprises boron carbide.

12. A kit of parts for a nuclear fission power plant configured for use in a terrestrial environment, the kit of parts being configured at least partially for assembly at the terrestrial environment and comprising: a nuclear reactor core;2024PF0024018 a containment vessel; a plurality of control drums; one or more control rods; a neutron reflector; a heat exchanger; a first pump; and an open Brayton cycle power system; the kit of parts being configured to be assembled to form: a gas circuit comprising: the first pump; a first passage through the heat exchanger; and the containment vessel; wherein the containment vessel is configured to contain at least: the neutron reflector, the neutron reflector comprising graphite disposed around a periphery of the nuclear reactor core; the plurality of control drums, configured to be disposed around the periphery of the nuclear reactor core; and the nuclear reactor core, the nuclear reactor core comprising: a moderator comprising graphite; at least one core inlet and at least one core outlet; one or more voids configured to receive the one or more control rods, the one or more control rods each being configured to be selectively insertable into a corresponding void in the nuclear reactor core; the nuclear reactor core being configured to accept a fuel system comprising TRISO fuel; the containment vessel further comprising a containment vessel inlet and a containment vessel outlet, the containment vessel inlet and containment vessel outlet being configured such that when assembled, gas can circulate around the gas circuit, flowing from the containment vessel inlet towards the nuclear reactor core, into the nuclear reactor core via the at least one core inlet, out of the nuclear reactor core via the at least one core outlet, and towards the containment vessel outlet; the open Brayton cycle power system being configured to be coupled to the gas circuit via the heat exchanger, the open Brayton power system comprising: a compressor; a turbine system; and a generator;2024PF0024019 the open Brayton power system being arranged such that when assembled, air can flow through the compressor, the heat exchanger, and the turbine system, wherein the heat exchanger is configured to permit heat in the gas flowing through the gas circuit to be transferred to the air from the compressor, and the turbine system is configured to drive the compressor and the generator.

13. The kit of parts of claim 12, further comprising a neutron shield configured to be disposed around a periphery of the neutron reflector.

14. A method for a nuclear fission power plant configured for use in a terrestrial environment, the method comprising controlling the nuclear fission power plant to: generate heat with a nuclear reactor core, the nuclear reactor core comprising a fuel system, a moderator, at least one core outlet, and at least one core inlet, wherein: a neutron reflector is disposed around a periphery of the nuclear reactor core; a plurality of rotatable control drums are disposed around the periphery of the nuclear reactor core; one or more control rods are configured to be selectively inserted into one or more corresponding voids in the nuclear reactor core; and a containment vessel is arranged to substantially surround the nuclear reactor core, the containment vessel comprising a containment vessel inlet and a containment vessel outlet, and being configured to define a flow path between the containment vessel inlet and the containment vessel outlet, such that gas following the flow path flows from the containment vessel inlet towards the nuclear reactor core, into the nuclear reactor core via the at least one core inlet, out of the nuclear reactor core via the at least one core outlet, and towards the containment vessel outlet; circulate gas around a gas circuit, including delivering the gas to the containment vessel inlet to be heated by the nuclear reactor core, and extracting the gas from the containment vessel outlet; and generate electricity with an open Brayton power system coupled to the gas circuit via a heat exchanger, the open Brayton power system comprising a compressor, a turbine system, and a generator, the open Brayton power system being arranged such that air flows through the compressor, the heat exchanger, and the at least one turbine, wherein the heat exchanger is configured to permit heat in the gas flowing through the gas circuit to be transferred to the compressed air from the compressor, and the at least one turbine is configured to drive the compressor and the generator.

Images