阅读说明：本技术 用于空间推进的径向流动高温气冷堆燃料组件及工作方法 (Radial flow high-temperature gas cooled reactor fuel assembly for space propulsion and working method ) 是由 章静 李彬乾 苏光辉 段子勉 王明军 巫英伟 田文喜 秋穗正 于 2021-07-19 设计创作，主要内容包括：本发明公开了一种用于空间推进的径向流动高温气冷堆燃料组件及工作方法,该燃料元件包括燃料组件底座、慢化剂区及其内外包壳、燃料环、燃料环堆叠固定装置、燃料组件顶盖,并给出了各部分的材料选择和连接方法。工作时,冷却剂由燃料组件顶盖上的入口进入燃料组件,流入位于燃料块区和慢化剂区中间的外腔进行流量分配,在通过燃料块的径向流道时被发生裂变反应的燃料块加热,温度升高,速度增加。冷却剂从径向流道流出之后在燃料组件内腔汇合搅混,最后从燃料组件底座的出口去往冷却剂喷射系统。由此燃料组件进行的核热推进堆芯设计所产生的用于空间推进的发动机将可以达到高的推力和比冲,从而允许航天器在太阳系内更远的地方执行任务。(The invention discloses a fuel component of a radial flow high-temperature gas cooled reactor for space propulsion and a working method thereof. During operation, coolant enters the fuel assembly from an inlet on the top cover of the fuel assembly, flows into an outer cavity between the fuel block area and the moderator area for flow distribution, and is heated by the fuel blocks which are subjected to fission reaction when passing through radial flow channels of the fuel blocks, so that the temperature is increased, and the speed is increased. The coolant flows out from the radial flow passages, then is mixed and stirred in the inner cavity of the fuel assembly, and finally goes to a coolant injection system from an outlet of the base of the fuel assembly. The engines for space propulsion resulting from the design of the nuclear thermal propulsion core by the fuel assembly will be able to achieve high thrust and specific impulse, allowing the spacecraft to perform tasks farther within the solar system.)

1. A radial flow high temperature gas cooled reactor fuel assembly for space propulsion, characterized by: the fuel assembly is based on the principle that radial flow increases the heat exchange area and volume ratio of nuclear fuel to improve the heat exchange capacity of fuel and coolant flow, and comprises a fuel assembly base (1) which is positioned at the bottommost part of the whole fuel assembly, supports the whole fuel assembly and is provided with an outlet for guiding the flow of high-temperature coolant; the fuel assembly cladding (2) is positioned above the periphery of the fuel assembly base (1), is connected with the fuel assembly base (1) by using a fusion welding method, protects the whole fuel assembly and is used for fixing and butting the components; the moderator area (3) is positioned above the periphery of the fuel assembly base (1) and in the fuel assembly cladding (2) and is used for moderating fast neutrons generated during fuel operation so as to facilitate continuation of the chain type fission reaction; a moderator zone cladding (4) located above the periphery of the fuel assembly base (1) and within the moderator zone (3), connected to the fuel assembly base (1) using a fusion welding process, for isolating the outer coolant cavity from the moderator zone, preventing corrosive damage to the moderator zone by the coolant at high temperatures; the fuel ring stacking area (5) is positioned right above the fuel assembly base (1) and formed by stacking nuclear fuel rings, wherein a plurality of radial flow channels for flowing of a coolant are formed in the fuel ring stacking area, and the radial flow channels are used for generating chain reaction and exchanging heat between the coolant and the high-temperature nuclear fuel; the fuel ring stacking area fastener (6) is positioned outside the fuel ring stacking area (5) and plays a role in position restraint on the fuel ring stacking area (5), and is connected with the fuel assembly base (1) by using a fusion welding method; a fuel ring stacking area top cover (7) which is positioned above the fuel ring stacking area (5) and is used for fixing a fastening piece (6) of the fuel ring stacking area, and the fuel ring stacking area top cover and the fastening piece (6) of the fuel ring stacking area are connected by using a fusion welding method; a fuel assembly top cover (8) positioned above the fuel ring stacking area top cover (7), connected with the fuel assembly cladding (2), the moderator area cladding (4) and the fuel ring stacking area top cover (7) by using a fusion welding method, used for fixing the whole fuel assembly and provided with an inlet for guiding the flow of low-temperature coolant; the middle of the fuel ring stacking area (5) and the moderator area cladding (4) is an outer cavity, and the middle of the fuel ring stacking area (5) is an inner cavity.

2. The fuel assembly of claim 1, wherein the fuel assembly is a radial flow high temperature gas cooled reactor fuel assembly for space propulsion, and comprises: the fuel assembly base (1) and the fuel assembly top cover (8) are made of W-3Re alloy.

3. The fuel assembly of claim 1, wherein the fuel assembly is a radial flow high temperature gas cooled reactor fuel assembly for space propulsion, and comprises: the fuel assembly cladding (2) and the moderator zone cladding (4) are fabricated using a W-25Re alloy.

4. The fuel assembly of claim 1, wherein the fuel assembly is a radial flow high temperature gas cooled reactor fuel assembly for space propulsion, and comprises: the fuel ring of the fuel ring stack (5) is made of a solid solution ceramic made of uranium carbide, zirconium carbide and niobium carbide.

5. The fuel assembly of claim 1, wherein the fuel assembly is a radial flow high temperature gas cooled reactor fuel assembly for space propulsion, and comprises: the neutron moderator adopted in the moderator zone (3) is high-purity graphite.

6. The fuel assembly of claim 1, wherein the fuel assembly is a radial flow high temperature gas cooled reactor fuel assembly for space propulsion, and comprises: the fuel ring of the fuel ring stacking area (5) is provided with a radial flow passage with a rectangular cross section for the flowing of the coolant.

7. The fuel assembly of claim 1, wherein the fuel assembly is a radial flow high temperature gas cooled reactor fuel assembly for space propulsion, and comprises: the fuel ring stack area (5) is secured by fuel ring stack area fasteners (6) attached to the fuel assembly base (1) and the fuel ring stack area top cover (7) using fusion welding.

8. The method for operating a fuel assembly of a radial flow high temperature gas cooled reactor for space propulsion as claimed in any one of claims 1 to 7, wherein: during operation, low-temperature coolant enters a fuel assembly from an inlet on a top cover (8) of the fuel assembly, flows into an outer cavity between a fuel ring stacking area (5) and a moderator area cladding (4) for flow distribution, is heated by fuel blocks which undergo fission reaction when passing through a radial flow channel on the fuel ring stacking area (5), and is increased in temperature and speed; after flowing out from the radial flow channels on the fuel ring stacking area (5), the coolant is merged and stirred in an inner cavity in the middle of the fuel ring stacking area (5), and finally goes to a coolant injection system from an outlet of the fuel assembly base (1).

9. The method of operation of claim 8, wherein: the coolant is hydrogen gas.

Technical Field

The invention belongs to the technical field of nuclear thermal propulsion systems and nuclear reactor systems, and particularly relates to a radial-flow high-temperature gas cooled reactor fuel assembly for space propulsion and a working method.

Background

Compared with the existing chemical rocket technology, the nuclear thermal propulsion system technology has the obvious advantages of high specific impulse, large effective load, long endurance time, capability of starting for multiple times and the like. Compared with chemical rockets, the nuclear thermal rocket can save about 1/3 cost for each space mission. However, in existing nuclear thermal propulsion projects, fuel elements present some material and configuration problems that limit the ultimate performance of these nuclear thermal propulsion engines. Fuel assemblies using single or multi-channel prismatic fuel blocks are difficult to manufacture, have high thermal instability, and have a small surface-to-volume ratio, resulting in a large core pressure drop, limiting the thrust-to-weight ratio of the engine to about 3 or 4. The core of a particle bed fuel element arrangement is composed of spherical fuel particles packed in a bed, surrounded by hexagonal moderator blocks which are grouped and fixed in a cylindrical vessel. Uranium carbide, as fuel, is confined in two concentric porous cylinders, allowing coolant/propellant to pass through. Due to pressure drop caused by corrosion of long flow channels of fuel elements, the nuclear thermal propulsion reactor core has lower specific impulse, lower thrust-weight ratio and lower cruising time, so that the requirements of a propeller on a control system are higher and higher, and the cost of controlling the reactor is higher and higher.

Disclosure of Invention

The object of the present invention is to overcome the disadvantages of the prior art and to provide a fuel assembly and operating method for a space-pushed radial flow high temperature gas cooled reactor, which overcomes the known problems including, but not limited to, pressure drop, corrosion, thermal instability and complexity of the manufacturing method, thereby optimizing the heat transfer performance and mechanical properties of the fuel, and providing a reference for the design of a high thrust and high specific impulse nuclear reactor core.

In order to achieve the purpose, the invention adopts the following technical scheme:

a fuel assembly of radial flow high temperature gas cooled reactor for space propulsion, the fuel assembly is based on the principle that radial flow increases the heat exchange area and volume ratio of nuclear fuel to improve the heat exchange capacity of fuel and coolant flow, and comprises a fuel assembly base 1 which is positioned at the bottommost part of the whole fuel assembly, supports the whole fuel assembly and is provided with an outlet for guiding the high temperature coolant flow; the fuel assembly cladding 2 is positioned above the periphery of the fuel assembly base 1, is connected with the fuel assembly base 1 by using a fusion welding method, protects the whole fuel assembly and is used for fixing and butting the assemblies; the moderator area 3 is positioned above the periphery of the fuel assembly base 1 and in the fuel assembly cladding 2 and is used for moderating fast neutrons generated during fuel operation so as to facilitate continuation of the chain fission reaction; the moderator zone cladding 4 is positioned above the periphery of the fuel assembly base 1 and in the moderator zone 3 and is connected with the fuel assembly base 1 by using a fusion welding method, and is used for isolating the coolant outer cavity from the moderator zone and preventing the high-temperature coolant from corroding and damaging the moderator zone; the fuel ring stacking area 5 is positioned right above the fuel assembly base 1 and formed by stacking nuclear fuel rings, wherein a plurality of radial flow channels for flowing of a coolant are formed in the fuel ring stacking area, and the radial flow channels are used for generation of chain reaction and flowing heat exchange of the coolant and high-temperature nuclear fuel; the fuel ring stacking area fastener 6 is positioned outside the fuel ring stacking area 5 and plays a role in position restraint on the fuel ring stacking area 5 and is connected with the fuel assembly base 1 by using a fusion welding method; a fuel ring stacking area top cover 7 which is positioned above the fuel ring stacking area 5 and is used for fixing a fuel ring stacking area fastener 6 and is connected with the fuel ring stacking area fastener 6 by using a fusion welding method; a fuel assembly top cover 8 positioned above the fuel ring stack area top cover 7, connected with the fuel assembly cladding 2, the moderator area cladding 4 and the fuel ring stack area top cover 7 by using a fusion welding method, used for fixing the whole fuel assembly and provided with an inlet for guiding the flow of the low-temperature coolant; the middle of the fuel ring stacking area 5 and the moderator area cladding 4 is an outer cavity, and the middle of the fuel ring stacking area 5 is an inner cavity.

The fuel assembly base 1 and the fuel assembly top cover 8 are fabricated using a W-3Re alloy.

The fuel assembly cladding 2 and moderator zone cladding 4 are fabricated using a W-25Re alloy.

The fuel rings of the fuel ring stack 5 are made of solid solution ceramics made of uranium carbide, zirconium carbide and niobium carbide.

The neutron moderator adopted in the moderator zone 3 is high-purity graphite.

The fuel ring of the fuel ring stacking area 5 is provided with a radial flow passage with a rectangular cross section for the flowing of the coolant.

The fuel ring stack area 5 is secured by fuel ring stack area fasteners 6 attached to the fuel assembly base 1 and the fuel ring stack area top cover 7 using a fusion welding process.

The working method of the radial flow high-temperature gas cooled reactor fuel assembly for space propulsion is characterized by comprising the following steps: during operation, low-temperature coolant enters the fuel assembly from an inlet on the top cover 8 of the fuel assembly, flows into an outer cavity between the fuel ring stacking area 5 and the moderator area cladding 4 for flow distribution, is heated by fuel blocks which undergo fission reaction when passing through a radial flow channel on the fuel ring stacking area 5, and is increased in temperature and speed; the coolant flows out from the radial flow channels on the fuel ring stacking area 5, then is mixed and stirred in the inner cavity in the middle of the fuel ring stacking area 5, and finally goes to a coolant injection system from the outlet of the fuel assembly base 1.

The coolant is hydrogen.

Compared with the prior art, the invention has the following advantages:

1. the fuel assembly of the present invention employs an assembly outer cavity-radial coolant flow passage-assembly inner cavity coolant flow passage arrangement as compared to conventional nuclear thermal propulsion fuel assemblies. Because of the existence of the outer cavity of the assembly, the coolant separates the high-temperature fuel area from the moderator, and only the fuel is in a high-temperature state when the whole fuel assembly works. The characteristic prolongs the service life of the structural material, and allows the components to adopt moderator materials with low melting point and better performance, so that the reactor core is more compact and the neutron leakage is reduced. The radial coolant runner that the subassembly adopted arranges, greatly increased the heat transfer area that flows between fuel and the coolant, improved heat exchange efficiency for the power of the reactor core of the same volume compares traditional fuel element reactor core power and improves by a wide margin.

2. According to the fuel assembly, the fuel ring is made of solid solution ceramic made of uranium carbide, zirconium carbide and niobium carbide, so that the fuel assembly has good working performance at high temperature, the fuel is prevented from being melted at high temperature, and the safety of nuclear heat propulsion is improved.

3. According to the fuel assembly, the neutron moderator adopted by the moderator area is high-purity graphite, so that the fuel assembly is good in high-temperature performance, good in neutron moderating capacity and low in cost, the neutron utilization rate of a reactor is improved, and the manufacturing cost of a reactor core is reduced.

4. According to the fuel assembly, the fuel ring in the fuel ring stacking area is provided with the radial flow channel which is rectangular in cross section and used for flowing of the coolant, so that the heat exchange area and the volume ratio of the nuclear fuel are improved, the heat exchange capacity of the fuel and the flowing of the coolant is improved, and the thermal instability of the fuel is prevented.

5. According to the fuel assembly, the coolant is guided into the relatively short radial flow channel on the fuel ring of the fuel ring stacking area through the flow distribution of the outer chamber, so that the pressure drop loss in the flow channel is reduced, and the corrosion of the flow channel is prevented.

6. The fuel assembly has the advantages of simple structure and connection mode, reduction of the process requirement of fuel element design, and strong practicability.

Drawings

FIG. 1 is a schematic diagram of the overall structure of a radial flow high temperature gas cooled reactor fuel assembly for space propulsion according to the present invention;

as shown in FIG. 1, 1 is the fuel assembly base, 2 is the fuel assembly cladding, 3 is the moderator zone, 4 is the moderator zone cladding, 5 is the fuel ring stack zone, 6 is the fuel ring stack zone fasteners, 7 is the fuel ring stack zone top cover, and 8 is the fuel assembly top cover.

Detailed Description

The invention is described in detail below with reference to the following figures and detailed description:

as shown in FIG. 1, the invention relates to a fuel assembly of a space-propulsion radial-flow high-temperature gas-cooled reactor, which is based on the principle that radial flow increases the heat exchange area and volume ratio of nuclear fuel to improve the heat exchange capacity of fuel and coolant flow, and comprises a fuel assembly base 1, a fuel assembly cladding 2, a moderator zone 3, a moderator zone cladding 4, a fuel ring stacking zone 5, a fuel ring stacking zone fastener 6, a fuel ring stacking zone top cover 7 and a fuel assembly top cover 8.

The fuel assembly base 1 is made of W-3Re alloy, supports the whole fuel assembly and is provided with an outlet for guiding the flow of high-temperature coolant; a fuel assembly enclosure 2, made of W-25Re alloy, located over the periphery of the fuel assembly base 1, joined to the fuel assembly base 1 using fusion welding, to protect the entire fuel assembly for fixation and butt-joint between the assemblies; a moderator zone 3 which is positioned above the periphery of the fuel assembly base 1 and in the fuel assembly cladding 2 is filled with high-purity graphite and is used for moderating fast neutrons generated during fuel operation so as to facilitate continuation of the chain type fission reaction; a moderator zone cladding 4 located above the periphery of the fuel assembly base 1 and within the moderator zone 3, fabricated from a W-25Re alloy, joined to the fuel assembly base 1 using fusion welding to isolate the outer coolant cavity from the moderator zone and prevent corrosive attack of the high temperature coolant on the moderator zone; the fuel ring stacking area 5 is positioned right above the fuel assembly base 1 and is formed by stacking nuclear fuel rings, the fuel rings are made of solid solution ceramics made of uranium carbide, zirconium carbide and niobium carbide, and a plurality of radial flow channels for flowing of a coolant are formed in the fuel rings for generation of chain reaction and flowing heat exchange of the coolant and high-temperature nuclear fuel; the fuel ring stacking area fastener 6 is positioned outside the fuel ring stacking area 5 and plays a role in position restraint on the fuel ring stacking area 5 and is connected with the fuel assembly base 1 by using a fusion welding method; a fuel ring stacking area top cover 7 which is positioned above the fuel ring stacking area 5 and is used for fixing a fuel ring stacking area fastener 6 and is connected with the fuel ring stacking area fastener 6 by using a fusion welding method; the fuel assembly top cover 8, which is positioned above the fuel ring stack area top cover 7, is connected with the fuel assembly cladding 2, the moderator area cladding 4 and the fuel ring stack area top cover 7 by using a fusion welding method, is used for fixing the whole fuel assembly, and is provided with an inlet for guiding the flow of the low-temperature coolant.

After all components are installed, when the nuclear thermal propulsion core works, low-temperature coolant enters the fuel assembly from an inlet on a top cover 8 of the fuel assembly, flows into an outer cavity between the fuel ring stacking area 5 and the moderator area cladding 4 for flow distribution, is heated by fuel blocks which have fission reaction when passing through a radial flow channel on the fuel ring stacking area 5, and is increased in temperature and speed. The coolant flows out from the radial flow channels on the fuel ring stacking area 5, then is mixed and stirred in the inner cavity in the middle of the fuel ring stacking area 5, and finally goes to a coolant injection system from the outlet of the fuel assembly base 1.

The foregoing is a further detailed description of the invention in connection with specific preferred embodiments and it is not intended that the specific embodiments of the invention be limited thereto, as variations and modifications to the above-described embodiments will occur to those skilled in the art, which are within the spirit and scope of the invention as defined in the appended claims.