CN110111912A - Spontaneous evaporation metal MHD integral reactor - Google Patents

Abstract

The invention discloses a kind of spontaneous evaporation metal MHD integral reactors, it include reactor pressure vessel, in-pile component, reactor core, inner magnet, starting motor and turbine in reactor, wherein, reactor pressure vessel by subcylindrical cylinder and lid is located at lid at the top of cylinder, the bottom (head) that is supported on cylinder body bottom forms.Out-of-pile includes outer magnet, rotary drum control rod, heat-pipe radiator, shielding construction.The present invention is suitable for fast reactor, applies also for other persistence heat sources such as isotope heat source；Meanwhile reactor structure size and output power adjustable extent are larger.

Description

Self-evaporating metal magnetic fluid integrated reactor

technical field

The invention belongs to the technical field of space small-scale nuclear power devices, and in particular relates to an integrated micro-reactor of self-evaporating metal magnetic fluid with full-environment automatic circulation capability.

Background technique

As the clean energy that is most likely to achieve large-scale and stable power generation, nuclear energy is one of the important ways to alleviate the contradiction between the environment and energy demand. The key to the application of nuclear energy lies in its safety. With the development of nuclear power technology, third-generation and fourth-generation nuclear power systems generally have passive safety features such as natural circulation of full power or partial power, and passive waste heat discharge.

At the same time, with the expansion of the scope of human space exploration and the extension of exploration time, it has become an important requirement for space exploration to be able to provide hundreds of kilowatts of power supply without relying on sunlight for several years. However, my country's isotope power supply raw material reserves are relatively small, and space reactors have become the main choice for the energy supply of the moon, Mars bases, and far-solar system probes.

The cooling methods of space reactors mainly include liquid metal cooling, gas cooling, liquid metal heat pipes, etc. Among them, although liquid metal heat pipes have high safety performance, the current technology is not yet mature; although liquid metal cooling and gas cooling methods are similar to ground nuclear power systems , but at present, the natural circulation of coolant in nuclear power systems depends on gravity and the difference in coolant density, and the natural circulation capacity cannot be guaranteed in the space environment. Therefore, pumps or fans can only be used to drive the cooling medium, and the failure of the pump or fan will cause the core to lose its cooling capacity. Risk of melting.

The energy conversion methods of space reactors mainly include thermocouples and thermions, Stirling cycle, closed Brayton cycle, etc. Among them, thermocouple conversion is the most widely used conversion method at present. However, the thermocouple conversion device has poor radiation resistance and low energy conversion efficiency - to achieve high conversion efficiency, it must have a very high hot end temperature. Therefore, Europe, the United States and my country are also vigorously promoting the Stirling cycle. Research on energy conversion methods such as closed Brayton cycle; the latter has high energy conversion efficiency, but as an energy conversion unit, compared with a thermocouple, the equipment per unit conversion power has a larger mass, a more complicated mechanical structure, and more moving parts. Many, especially closed Brayton cycles.

The invention solves the problem that the natural circulation of nuclear reactor coolant must rely on gravity, and realizes the passive safety of reactor core cooling under the action of no gravity; at the same time, it solves the problem that the external heat engine energy conversion system of the space reactor is too large, and the mechanical structure is complex and fragile problem, a highly integrated integrated reactor structure is realized.

Contents of the invention

The purpose of the present invention is to provide a self-evaporating metal magnetic fluid integrated micro-reactor with the ability of automatic circulation in the whole environment. The liquid metal cooling method realizes the automatic circulation ability under space conditions, and at the same time adopts a relatively simplified and integrated energy conversion structure. Higher conversion efficiency at lower hot junction temperature.

The present invention has adopted following technical scheme:

The self-evaporating metal magnetic fluid integrated reactor has the following structure: the reactor includes a reactor pressure vessel, reactor internals, a reactor core, a central magnet, an inner magnet, a starter motor and a turbine; the outside of the reactor includes an outer magnet located at a position corresponding to the inner magnet , drum control rods, heat pipe radiators and shielding structures; among them, the reactor pressure vessel is composed of a nearly cylindrical cylinder, a cover on the top of the cylinder, and a bottom head supported on the bottom of the cylinder. Inside the cylinder is a shroud for internal components, which divides the space of the pressure vessel into two areas, inside and outside; the upper part of the shroud for internal components is provided with a central magnet and an inner magnet, and a coolant flow channel is formed between the central magnet and the inner magnet. There is a core at the lower part of the inner shroud, which is a cylindrical core arranged with elongated cylindrical fuel elements, or a cylindrical core with elongated cylindrical coolant flow channels, through which the fuel element support It is fixed in the middle and lower part of the reactor internals shroud, and the top of the core coolant flow channel is set in the shape of a nozzle; above the nozzle is a turbine, which is connected to the impeller below the core through the axle passing through the core; the outside of the pressure vessel is in the active area of the core A number of circularly arranged drum control rods are set at the height, the drum is cylindrical, the main structure and the outer structure on one side of the circumference are neutron reflective materials, and the outer structure on the other side is neutron absorbing material, which can be adjusted by rotating the drum The control rod absorbs the neutrons of the core to adjust the reactivity of the core; the rotating shaft of the lower part of the drum is inserted into the bottom shielding structure, and the upper part is connected to the rotating motor; the rotating motor is inserted into the cylinder of the rotating drum.

The reactor cycle process is as follows: between the reactor internals shroud and the pressure vessel cylinder is the area where the metal magnetic fluid coolant of the core flows downward. The metal magnetic fluid coolant is partially vaporized when passing through the core, and flows upward from the nozzle. The injection drives the gas-liquid two-phase flow of the metal magnetic fluid to move upward, converting heat energy into mechanical energy; during the upward movement of the metal magnetic fluid, it passes through the flow channel between the central magnet and the inner magnet, cuts the magnetic induction line to generate electricity, and converts the mechanical energy into Electric energy; the metal ferrofluid moves upward to the top cover of the pressure vessel, then moves downward from the area between the reactor internals shroud and the pressure vessel shell, passes through the flow channel between the inner magnet and the outer magnet, and cuts the magnetic induction line again Power generation, converting mechanical energy into electrical energy; during the downward movement of the metal magnetic fluid, the heat pipe radiator outside the pressure vessel cylinder will export the waste heat to the cooling plate, and the cooled liquid metal magnetic fluid will flow back to the lower part of the core; the metal magnetic fluid In the process of spraying upward from the core nozzle, the turbine is driven, and the turbine is connected to the impeller at the lower part of the core to rotate, and the cooled liquid metal magnetic fluid is drawn into the core and partially gasified to form a complete coolant cycle; at the bottom of the reactor internals Set the starting engine, before the reactor is started and the coolant circulation is not established, the starting engine (in the case, a free piston Stirling engine) is used between the core coolant and the bottom of the reactor internals, the temperature difference drives the free piston Stirling engine to move, and the The power piston drives the plunger pump to pump the coolant into the core, and other engines can also be used) to form a cycle.

Wherein, a starter motor is arranged at the bottom of the internal components of the stack.

Wherein, the engine is a Stirling engine.

Wherein, a molybdenum-rhenium alloy thin layer is provided on the periphery of the core.

Among them, the height range of the core active area outside the lower cylinder of the pressure vessel is provided with a reflective layer with a drum structure; one side of the drum is provided with a boron carbide absorber, and the neutron absorption of the reflective layer is adjusted by controlling the rotation of the drum by a motor , and then control the core reactivity.

Among them, when the motor loses power, the boron carbide absorber will automatically turn to the side of the reactor core, so as to realize shutdown; at the same time, the drum can partially slide out of the active section of the core, and when the reactor is overheated, the drum will be fixed. When the gas chamber loses pressure, the drum partially slides out of the active section of the core under the action of the spring force, thereby realizing shutdown.

Among them, there is a circle of heat pipes outside the cylinder of the pressure vessel; the lower part of the heat pipe is inserted into the heat pipe seat that is close to the pressure vessel, and the heat pipe section in contact with the pressure vessel in the heat pipe seat becomes the hot end of the heat pipe, and the cold end of the heat pipe is connected to the radiator through heat radiation. waste heat emissions.

Wherein, the bottom and side of the pressure vessel cylinder are respectively provided with a bottom shield and a side shield for reducing the radiation dose outside the reactor.

Among them, the cylinder body of the pressure vessel is welded to the bottom head, the top cover of the pressure vessel is connected to the flange of the cylinder body through main bolts, and two sealing rings are provided on the sealing surface.

Among them, a liquid metal coolant with a low boiling point is used, the core temperature is higher than the boiling point, and the coolant is partially vaporized when passing through the core.

Among them, a turbine is set above the core, and the mechanical energy of the two-phase flow metal coolant injection is used to drive the turbine to rotate, and then the coolant is pumped into the core at the lower part of the core to maintain the coolant circulation.

Further, the coolant is liquid metal magnetic fluid with low boiling point, liquid metal magnetic fluid Na or NaK alloy.

The beneficial effects of the present invention are:

(1) The full-power automatic circulation system that does not depend on gravity can have passive safety performance in various environments such as space, lunar surface, Mars, and underwater, as well as various attitudes such as tilting and swinging;

(2) The automatic cycle power does not come from the difference in coolant density, and can realize full-power automatic cycle at high power density and low coolant flow channel height;

(3) Adopting a highly integrated modular structure, the reactor core, energy conversion structure, generator, and circulating medium are all arranged in a pressure vessel, which has high safety performance;

(4) Full external power control to improve the safety of the pressure boundary;

(5) The power control system with double passive safety design is adopted, and the two shutdown systems are independent of each other, which can realize passive shutdown under the conditions of power failure and over temperature, and have high passive safety performance;

(6) Passive waste heat discharge function, which can completely discharge waste heat without any external intervention after shutdown;

(7) Using magnetic fluid to generate electricity can achieve higher thermoelectric conversion efficiency and higher power density;

(8) The energy conversion process can automatically follow the change of the core power to realize the automatic adjustment of the output power;

(9) The reactor structure is simple, there are no components such as control rod drives with complicated mechanical structures, and there are no multiple coolant circuits, which has higher energy conversion efficiency and reliability;

(10) Compared with gaseous magnetic fluid, liquid metal magnetic fluid can work at a relatively low temperature, reducing the requirements for reactor materials;

(11) The modular structure that directly outputs electric energy is suitable for mass production and assembly, and can adapt to the needs of different powers by changing the number of modules;

(12) The basic structure of the reactor has a wide range of applications, not only for fast reactors, but also for other persistent heat sources such as isotope heat sources; at the same time, the reactor structure size and output power can be adjusted in a large range.

Description of drawings

Fig. 1 is the overall structure schematic diagram of self-evaporating metal magnetic fluid integrated reactor of the present invention;

Fig. 2 is the structural representation of the pressure vessel in the self-evaporating metal magnetic fluid integrated reactor structure of the present invention;

Fig. 3 is the internal structural representation of the pressure vessel in the self-evaporating metal magnetic fluid integrated reactor structure of the present invention;

Fig. 4 is a structural schematic diagram of the outside of the pressure vessel in the self-evaporating metal magnetic fluid integrated reactor structure of the present invention;

Among them, 1 is the pressure vessel; 2 is the internal components of the reactor; 3 is the core; 4 is the inner magnet; 5 is the outer magnet; 6 is the center magnet; 7 is the starting engine; 8 is the turbine; 11 is a side shield; 12 is a bottom shield.

Detailed ways

The specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, but it should be noted that these specific embodiments are only exemplary and not intended to limit the protection scope of the present invention.

Referring to Fig. 1, Fig. 1 has shown the overall structure schematic diagram of self-evaporating metal magnetic fluid integrated reactor of the present invention; Wherein, the specific structure of the reactor of the present invention comprises: pressure vessel 1, reactor internals 2, core 3, inner magnet 4. Outer magnet 5, center magnet 6, starter motor 7, turbine 8, drum reflection layer 9, heat pipe and heat pipe holder 10, side shield 11, bottom shield 12, etc. Among them, the reactor internals 2, core 3, inner magnet 4, center magnet 6, starter engine 7, and turbine 8, which are used to convert fission heat into electrical energy, organize coolant channels, and form automatic circulation capabilities, are all arranged in the pressure vessel Inner and outer magnets 5, drum reflectors 9 for waste heat discharge, reactivity control and shielding functions, heat pipes and heat pipe holders 10, bottom shielding structure 12, etc. are arranged outside the pressure vessel.

Specifically, referring to Fig. 2, Fig. 2 has shown the structural representation of the pressure vessel in the self-evaporating metal magnetofluidic integrated reactor structure of the present invention, wherein the reactor pressure vessel 1 consists of a nearly cylindrical cylinder body and a cover located on the cylinder body It is composed of the top cover and the bottom head supported on the bottom of the cylinder; the shroud and the bottom head are welded, the pressure vessel top cover and the upper flange of the shroud are connected by main bolts, and the sealing surface is provided with 2 sealing rings.

Inside the cylinder of the pressure vessel, there is a shroud 2 for internals, which divides the space in the lower section of the pressure vessel 1 into two areas, inside and outside; inside the shroud 2, there is a core 3, and the inside of the shroud is where the coolant flows upwards. Area; between the reactor internals shroud and the lower cylinder of the pressure vessel is the area where the coolant flows downward; the lower end of the shroud is radially limited by the boss at the bottom of the pressure vessel shroud.

Referring to Fig. 3, Fig. 3 has shown the structure diagram inside the pressure vessel in the self-evaporating metal magnetofluid integrated reactor structure of the present invention, the inside of the pressure vessel 1 is also provided with a core 3 and an inner magnet in addition to the reactor internals shroud 2 4. The central magnet 6, the starting engine 7, the turbine 8, and the core structure can be arranged in the form of elongated cylindrical fuel elements. Under this design, the outside of the core structure is a thin-walled core cylinder, and the cylinder connects several layers of fuel elements The grating (three layers in the figure); the grating not only limits the radial position of the fuel element, but also has a coolant channel; the core structure can also be a cylindrical fuel core with a slender cylindrical coolant channel. The core structure is installed in the lower part of the reactor internals shroud; on the upper part of the reactor internals shroud, a central magnet is arranged above the core structure; an inner magnet is arranged around the central magnet, and the annular space between the central magnet and the inner magnet It is the coolant ascending channel; several nozzle structures are arranged above the core structure to guide the coolant into the ascending channel between the central magnet and the inner magnet; several small turbines are arranged in the coolant channel above the nozzle, and each turbine passes through the The axle passing through the core is connected with the impeller below the core, driving the impeller to rotate together with the turbine; the bottom of the internal components is provided with a starting engine.

In a specific embodiment, the heated liquid metal magnetic fluid coolant in the core 3 is partially vaporized, and the volume expands violently, and the two-phase flow metal magnetic fluid is ejected from the upper nozzle of the core at high speed, converting heat energy into mechanical energy; On the one hand, the ejected magnetic fluid drives the turbine to rotate, on the other hand, it cuts the magnetic induction line to generate electricity, and converts mechanical energy into electrical energy; after the two-phase flow magnetic fluid reaches the top cover of the pressure vessel, it extends the gap between the inner component casing and the pressure vessel cylinder. The space moves downward to cut the magnetic induction line again, and at the same time, the heat pipe radiator outside the pressure vessel takes away the waste heat; the cooled liquid metal magnetic fluid flows to the bottom of the core, and the impeller driven by the turbine is drawn into the core to realize the cooling of the magnetic fluid The agent circulates automatically.

Further, the pressure vessel is equipped with drum reflectors, heat pipes, side shields and bottom shields, as shown in Figure 4 .

The drum reflective layer is arranged in a circle around several drums outside the lower casing of the pressure vessel; its main structure and the outer layer structure on one side of the circumference are neutron reflective materials, and the outer layer structure on the other side is neutron absorbing material. Material, adjust the reactivity of the core by rotating the drum; the rotating shaft at the lower part of the drum is inserted into the bottom shielding structure, and the upper part is connected to the rotating motor; the rotating motor is inserted into the cylinder of the drum.

The lower part of the heat pipe is inserted into the heat pipe seat near the reactor to improve heat exchange efficiency; the heat pipe seat is close to the pressure vessel cylinder to improve the heat exchange efficiency between the heat pipe and the coolant in the pressure vessel; the upper part of the heat pipe protrudes from the upper space of the pressure vessel, Connected to the heat dissipation structure; a large number (12 in the figure) of heat pipes are arranged around the pressure vessel casing.

The parts other than the above structure are side shield structure and bottom shield structure.

Specific embodiment 1 is given below in order to illustrate the structure of the present invention in more detail.

Example 1

(1) The main body of the reactor is a nearly cylindrical pressure vessel, the outer diameter of the pressure vessel shroud is 280mm, the height is 660mm, the wall thickness of the pressure vessel cylinder is 20mm, the nominal diameter of the main bolt is 10mm, and the number is 24; the reactor core, energy conversion structure, magnetic The fluid generator and circulating medium are all arranged in the pressure vessel; the reflection layer structure with a drum used to control the reactivity of the core is arranged outside the pressure vessel with thermodynamic working medium tubes.

(2) The lower part of the pressure vessel cylinder is equipped with a shroud for internal components, which divides the space of the lower section of the pressure vessel into two areas: inner and outer; the outer diameter of the inner member shroud is 220mm, the height is 480mm, and the wall thickness is 10mm.

(3) The uranium nitride fuel elements with a diameter of 14mm and a length of 200mm are arranged into a cylindrical core with a diameter of 200mm and a height of 200mm, which are fixed in the lower part of the reactor internals casing through the fuel element bracket, and the fuel enrichment degree is 98%; A thin layer of molybdenum-rhenium alloy with a thickness of 2 mm is provided on the periphery of the core.

(4) Inside the shroud of the reactor internals, an inner magnet is arranged above the core structure, the height of the inner magnet is 250mm, and the thickness is 35mm; the diameter of the central magnet is 50mm, and the height is 250mm; the width of the coolant channel passing between the inner magnet and the central magnet 35mm; the outside of the pressure vessel is equipped with an outer magnet at the same height as the inner magnet, with a thickness of 30mm; the width of the coolant channel between the internal component cylinder and the pressure vessel cylinder is 25mm, passing between the inner and outer magnets.

(5) On the outer side of the lower part of the pressure vessel, there is a beryllium oxide reflective layer with a drum structure in the height range of the core active area. The reflective layer has a thickness of 100mm and a height of 200mm; the diameter of the drum is 80mm, and a boron carbide absorber with a thickness of 20mm is installed on one side of the circumference. , the neutron absorption of the reflective layer is adjusted by controlling the rotation of the drum by the motor, and then the reactivity of the reactor core is controlled. Move 200mm out of the active section of the core. When the temperature of the hot end of the heat pipe exceeds 200°C due to the overheating of the reactor, the air chamber fixed by the drum will lose pressure, and the drum will partially slide out of the active section of the core under the action of the spring force, thereby Realize shutdown.

(6) There are 12 heat pipes on the outside of the pressure vessel cylinder. The heat pipes exchange heat with the pressure vessel cylinder through the aluminum alloy heat pipe seat. The diameter of the heat pipes is 20mm, and the total number is 24; The cold end uses a radiator to discharge waste heat, and the surface area of the radiator is 200m ² .

(9) The metal magnetic fluid is Na (in other embodiments, it may also be NaK alloy, etc.).

(10) The magnet system is provided by a ceramic insulating sheathed Helmertz coil.

The operating parameters of this embodiment are as follows:

(1) Rated electric power 200kw;

(2) The core temperature is 900°C;

(3) The design pressure is 10MPa;

(4) The temperature at the high temperature end of the heat pipe is 150°C, and the temperature at the low temperature end is 120°C.

Although the specific implementation of the patent of the present invention has been described and illustrated in detail above, it should be noted that we can make various equivalent changes and modifications to the above-mentioned implementation according to the concept of the patent of the present invention. If it still does not exceed the spirit contained in the description and drawings, it should be within the protection scope of the patent for the present invention.

Claims (12)

1. Self-evaporating metal magnetic fluid integrated reactor, the reactor includes a reactor pressure vessel, reactor internals, reactor core, inner magnet, starter motor and turbine, wherein the reactor pressure vessel consists of a nearly cylindrical cylinder and a cover set on the cylinder It consists of a cover on the top of the cylinder and a bottom head supported on the bottom of the cylinder; the outside of the reactor includes external magnets, drum control rods, heat pipe radiators and shielding structures; Internals shrouds are installed inside the pressure vessel cylinder, which divides the space of the pressure vessel into two areas, inside and outside; the core is provided at the middle and lower part of the reactor internals shroud, and there is a cooling system between the reactor internals shroud and the pressure vessel shell. The area where the agent flows downward; the coolant of the core is a liquid metal magnetic fluid Na or NaK alloy with a low boiling point, and the temperature of the core is higher than the boiling point of the coolant. Square injection drives the gas-liquid two-phase flow of the metal magnetic fluid to move upwards, converting heat energy into mechanical energy; during the upward movement of the metal magnetic fluid, it passes through the flow channel between the central magnet and the inner magnet, cuts the magnetic induction line to generate electricity, and converts mechanical energy It is electric energy; the metal ferrofluid moves upward to the top cover of the pressure vessel and then moves downward from the area between the shroud of the reactor internals and the cylinder of the pressure vessel, passing through the flow channel between the inner magnet and the outer magnet, and cutting the magnetic induction again Line power generation, converting mechanical energy into electrical energy; during the downward movement of the metal magnetic fluid, the heat pipe radiator outside the pressure vessel cylinder will export the waste heat to the cooling plate, and the cooled liquid metal magnetic fluid will flow back to the lower part of the core; When the metal magnetic fluid is sprayed upward from the core nozzle, it drives the turbine, and the turbine is connected to the impeller at the lower part of the core to rotate, and the cooled liquid metal magnetic fluid is drawn into the core, and partially gasified to form a complete coolant cycle; A starting Stirling engine is installed at the bottom of the internals. Before the reactor is started and the coolant circulation is not established, the temperature difference between the core coolant and the bottom of the pressure vessel drives the free piston Stirling engine to move, and the plunger pump is driven by the power piston to cool the engine. The agent is pumped like the core to form a circulation. 2. The reactor as claimed in claim 1, wherein magnets are arranged inside and outside the upper cylinder of the pressure vessel; the magnets are arranged on the inner and outer sides of the coolant flow channel surrounded by the reactor internals cylinder and the pressure vessel cylinder . 3. The reactor according to claim 1, wherein a starting motor is provided at the bottom of the pressure vessel. 4. The reactor according to claim 1, wherein the reactor core is a cylindrical core arranged with elongated cylindrical fuel elements, or a cylindrical core with elongated cylindrical coolant passages, through The fuel element support is fixed at the middle and lower part of the internals shroud, and the top of the core coolant flow channel is set in the shape of a nozzle. 5. The reactor as claimed in claim 1, wherein a molybdenum-rhenium alloy thin layer is provided on the periphery of the core. 6. The reactor as claimed in any one of claims 1-5, wherein the height range of the core active zone outside the lower cylinder of the pressure vessel is provided with a reflective layer with a drum structure; one side of the drum is provided with a boron carbide absorber The motor controls the rotation of the drum to adjust the neutron absorption of the reflective layer, thereby controlling the reactivity of the core. 7. The reactor as claimed in claim 6, wherein when the motor loses power, the boron carbide absorber will automatically turn to the side of the reactor core, thereby realizing shutdown; the rotating drum can partially slide out of the active section of the core simultaneously, when When the reactor is overheated, the air chamber fixed by the drum will be depressurized, and the drum will partially slide out of the active section of the core under the action of the spring force, thereby realizing shutdown. 8. The reactor according to any one of claims 1-5, wherein a circle of heat pipes is arranged outside the pressure vessel cylinder; the heat pipe section in contact with the pressure vessel becomes the hot end of the heat pipe, and the cold end of the heat pipe adopts a radiator to discharge waste heat. 9. The reactor according to any one of claims 1-5, wherein the bottom and side portions of the pressure vessel shell are provided with bottom shields and side shields, respectively. 10. The reactor as claimed in claim 1, wherein the cylinder body of the pressure vessel is welded to the bottom head, the top cover of the pressure vessel is connected to the flange of the cylinder body through main bolts, and two sealing rings are provided on the sealing surface. 11. The reactor of claim 1, wherein a liquid metal coolant with a low boiling point is used, the temperature of the core is above the boiling point, and the coolant is partially vaporized while passing through the core. 12. The reactor as claimed in claim 1, wherein a turbine is arranged above the core, and the mechanical energy injected by the two-phase flow metal coolant is used to drive the turbine to rotate, and then the coolant is pumped into the core at the lower part of the core to maintain the circulation of the coolant .