Laser inertial fusion hohlraum and method of designing the same

Abstract

The application discloses a laser inertial fusion cladding and a design method thereof. The cladding is divided into a tungsten armor, a first wall, a tritium breeding self-cooling area and a back plate from near to far according to the distance from the fusion reaction center. The design method firstly establishes a simplified radial partition three-dimensional model of the cladding, then performs neutron transport calculation on the model to obtain the tritium breeding rate and the nuclear heat deposition spatial distribution of the cladding, combines material characteristics to perform thermal calculation and obtain the temperature distribution in the cladding, comprehensively considers the tritium breeding rate and the temperature distribution, adopts an optimization algorithm to determine the reasonable interval of the radial size of each functional area of the cladding, then performs fine modeling, and optimizes the design in the interval until the standard is met. The fusion cladding and the design method thereof can replace the complete cladding model in the traditional cladding engineering design with the spherical radial partition model on the basis of ensuring the accuracy, avoid the establishment of a complex model in the multi-physical field coupling calculation, optimize the design process of the cladding, and design the cladding suitable for the laser inertial confinement fusion.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser fusion blanket design, in particular to a laser inertial fusion blanket and a design method thereof. BACKGROUND

[0002] The laser fusion blanket is an energy conversion structure of the laser inertial confinement fusion reactor, and also shoulders the functions of tritium breeding, containment of the reactor core and neutron shielding. During the operation of the fusion reactor, the reactor core is in a high-temperature plasma state, and emits target pellet fragments, high-energy neutrons, and various radiation products, which bring extremely high instantaneous load to the overall blanket and bring great challenges to the design of the blanket structure.

[0003] Unlike the development of better magnetic confinement fusion blankets, the design of domestic and international laser fusion blankets is still in its infancy. At the same time, due to the absence of a strong magnetic field, liquid tritium breeders that are easy to manufacture, have better tritium production rates and cooling performance can be selected for tritium breeding. However, the corrosion of liquid tritium breeders on the structure of the blanket material is continuously strengthened with the increase of temperature, so controlling the temperature of the tritium breeder and the interface between the structure material becomes the key to the design of the blanket.

[0004] Traditional magnetic confinement fusion blanket design usually establishes a complete model of the blanket and performs analysis, but the overall size of the blanket is generally in meters, and the structure involving fluid in the blanket is extremely fine, which requires fine modeling. The design of the laser inertial confinement fusion reactor blanket generally refers to the design process of the magnetic confinement fusion blanket, and the work is extremely tedious and arduous. SUMMARY

[0005] To solve the problems in the prior art of laser fusion blanket design, the present application aims to design a blanket suitable for laser inertial confinement fusion, and proposes a design method that ensures design accuracy and avoids the establishment of a complete complex model of the blanket in traditional blanket engineering design, thereby making up for the deficiency of the huge workload of existing laser fusion blanket design.

[0006] The present application achieves the above-mentioned purpose by adopting the following technical solutions:

[0007] A laser inertial fusion blanket, which is spherical as a whole, is divided into several arc-shaped sub-blankets by equator lines, and each arc-shaped sub-blanket is divided into several blanket modules by parallel lines, wherein one blanket module near two poles is left empty as an entrance for an external device of the blanket; each functional area of the blanket module is divided into a tungsten armor 1, a first wall 2, a tritium breeding self-cooling area 3, and a back plate 4 from near to far according to the distance from the fusion reaction center; the tungsten armor 1 and the front end first wall 2 are formed by diffusion welding of multiple layers of low-activity ferrite and martensite steel, wherein each layer of steel plate adopts laser etching micro-channels to ensure the structural strength and improve the cooling efficiency of the supercritical carbon dioxide of the blanket coolant; the tritium breeding self-cooling area 3 adopts liquid lithium-lead alloy, and is divided into three sub-areas by multiple layers of welded steel plates with built-in laser etching micro-channels, wherein the laser etching micro-channels with high heat exchange efficiency can fully utilize the cooling capacity of the supercritical carbon dioxide of the blanket coolant, effectively control the temperature of the liquid lithium-lead interface of the steel plate, reduce the corrosion of the liquid lithium-lead to the structural material of the blanket, and improve the overall service life of the blanket; the back plate 4, as the outermost structure of the blanket, directly contacts the inner part of the liquid lithium-lead alloy, is formed by multiple layers of welded steel plates with built-in laser etching micro-channels, and is internally connected with the supercritical carbon dioxide as a coolant to carry away heat, so as to control the temperature of the back plate-liquid lithium-lead alloy interface below the strong corrosion temperature threshold; the outer part of the back plate is completely formed by low-activity ferrite and martensite steel to improve the overall structural strength of the blanket module, and serves as a support surface for the external device of the blanket.

[0008] Preferably, the spherical laser inertial fusion blanket is divided into 24 arc-shaped sub-blankets by equator lines, and each arc-shaped sub-blanket is divided into 9 blanket modules by parallel lines.

[0009] The design method of the laser inertial fusion blanket comprises the following steps:

[0010] Step 1: Establishing a three-dimensional model of the spherical blanket

[0011] According to the structure of the laser inertial fusion blanket, the radial distribution and size of the functional areas in the spherical blanket are determined, and a corresponding simplified three-dimensional model of the spherical blanket is established;

[0012] Step 2: Sub-blanket neutron transport calculation

[0013] According to the design parameters of the laser fusion core, the neutron characteristics of the blanket material, and the preliminary design structural parameters of the blanket, the three-dimensional model of the spherical blanket established in step 1 is calculated by using the Monte Carlo method and a neutron transport program, so as to obtain the spatial distribution of nuclear heat deposition and the overall tritium breeding rate in the laser inertial fusion blanket, and to determine the preliminary size of the functional area of the tritium breeding self-cooling area;

[0014] Step 3: Thermal-hydraulic calculation of the spherical blanket

[0015] According to the fluid and solid heat transfer principle, the laser etching micro-channel design preliminary parameters of the flow channel size, coolant flow and steel plate thickness are obtained by using the coolant property and the convection heat transfer coefficient numerical calculation method; according to the geometric structure of the laser inertial fusion blanket and the thermal hydraulic characteristics of the blanket material, the thermal hydraulic analysis model of the laser inertial fusion blanket is established by using the CFD program, and the first wall surface heat flux density distribution obtained by the core design parameters and the laser etching micro-channel design preliminary parameters are combined with the nuclear heat deposition spatial distribution in the laser inertial fusion blanket obtained in step 2 to obtain the preliminary temperature distribution of the material in the laser inertial fusion blanket;

[0016] Step 4: Multi-physical field coupling iterative calculation of spherical blanket

[0017] Due to the different laser fusion core design parameters and the temperature limit of the blanket material, different blanket structures are suitable, so multiple calculations are needed to obtain the radial size interval of the functional area in the blanket, that is, steps 2 and 3 are performed multiple times, but the "blanket preliminary design structure parameters" used in the first step 2 need to be changed to the corresponding blanket design structure parameters in the subsequent implementation process, and the radial size interval of the functional area in the blanket suitable for the laser fusion core design parameters and the temperature limit of the blanket material is obtained after iterative calculation, and in the multiple calculation process, different optimization algorithms are used to determine the radial size interval of the functional area in the blanket more quickly;

[0018] Step 5: Fine three-dimensional blanket optimization design

[0019] A complete three-dimensional model of the overall blanket is established---the neutron transport program and the CFD program of the Monte Carlo method are used to establish the fine model of the neutron transport and thermal hydraulic of the blanket, in which the finite volume method and the Monte Carlo method are used to discretize the partial differential equations of the temperature field and the neutron transport field respectively, and the grid sizes obtained by the two methods for the same geometric structure are different, especially the grid cells obtained by the Monte Carlo method have less flexibility than the grid cells obtained by the finite volume method, so the volume weighted average method is needed to transfer data between grids, and the direct coupling calculation of neutron transport and thermal hydraulic is carried out, and the radial size interval of the functional area in the blanket obtained in step 4 is combined with the laser inertial fusion blanket design standard to determine the blanket optimization design structure parameters.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] 1. According to the laser inertial confinement fusion reaction process and characteristics, a blanket suitable for laser fusion reaction is designed, and the laser etching micro-channel is used to fully cope with the high peak and short period heat flux density brought by the laser inertial confinement fusion to the first wall, and to control the temperature of the liquid lithium lead and the interface of the blanket structure material.

[0022] 2, The application is based on the cross of multiple disciplines such as neutron science and heat transfer, and obtains the multi-physical field coupling design technology of the laser fusion blanket by comprehensively considering the laser inertial confinement fusion process characteristics and product spatial distribution, adopting the three-dimensional spherical blanket simulation step as the pre-design of the traditional blanket design, breaking through the limitation of the huge and complicated workload of the laser fusion blanket design brought by the traditional blanket design process, and obtaining the reasonable interval of the subsequent blanket fine design through the overall blanket simplified model calculation of the radial functional area arranged in turn.

[0023] 3, The application fully considers the laser inertial confinement fusion process characteristics and product spatial distribution, adopts the three-dimensional spherical blanket simulation step as the pre-design of the traditional blanket design, breaks through the limitation of the huge and complicated workload of the laser fusion blanket design brought by the traditional blanket design process, and obtains the reasonable interval of the subsequent blanket fine design through the overall blanket simplified model calculation of the radial functional area arranged in turn.

[0024] 4, The application adopts the multi-physical field coupling to study the laser fusion blanket design, and provides a reliable calculation method for the conceptual design of the laser fusion blanket.

[0025] In summary, the application designs a blanket suitable for laser inertial confinement fusion, and proposes a corresponding design method, which can establish the optimization design process of the laser inertial fusion blanket based on the Monte Carlo method, neutron transport, thermal hydraulic and other means, remove the redundant and complicated blanket overall modeling work, and provide guidance for the actual operation of the laser inertial fusion blanket. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic diagram of the optimization design method process of the laser inertial fusion blanket.

[0027] Figure 2 It is a schematic diagram of the overall structure of the laser inertial fusion blanket.

[0028] Figure 3 It is a schematic diagram of the local section of the laser inertial fusion blanket. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0030] As Figure 2 And Figure 3As shown in the figure, the application is applied to the spherical overall cladding of laser inertial fusion, in the embodiment, the spherical cladding is divided into 24 arc sub-claddings by equator, each arc sub-cladding is divided into 9 cladding modules by parallel, and one of the cladding modules near the two poles is left as an entrance of a cladding external device. The functional areas of the cladding modules are divided into the tungsten armor 1, the first wall 2, the tritium breeding self-cooling area 3 and the back plate 4 from the near to the far according to the distance from the fusion reaction center. The tungsten armor 1 and the front end first wall 2 are formed by diffusion welding of multiple low-activity ferrite and martensite steel plates, each of which is provided with laser etching micro-channels to ensure the structural strength and improve the cooling efficiency of the supercritical carbon dioxide coolant of the cladding. The tritium breeding self-cooling area 3 is made of liquid lithium-lead alloy and is divided into three sub-areas by multiple welding steel plates provided with the above-mentioned built-in laser etching micro-channels. The laser etching micro-channels with high heat exchange efficiency can make full use of the cooling capacity of the supercritical carbon dioxide coolant of the cladding, effectively control the temperature of the liquid lithium-lead interface of the steel partition plate, reduce the corrosion of the liquid lithium-lead to the cladding structural material and improve the overall service life of the cladding. The back plate 4 is the outermost structure of the cladding, the inner part directly contacting the liquid lithium-lead alloy is made of multiple welding steel plates provided with the above-mentioned built-in laser etching micro-channels and is internally connected with the supercritical carbon dioxide as a coolant to take away heat, so as to control the temperature of the back plate-liquid lithium-lead alloy interface below the strong corrosion temperature threshold. The outer part of the back plate is made of low-activity ferrite and martensite steel to improve the overall structural strength of the cladding module and serve as a support surface for the cladding external device.

[0031] As shown in the figure, the design method of the laser inertial fusion cladding of the application comprises the following steps: Figure 1

[0032] 1. According to the core design requirements of CFETR phase I and the requirements of laser fusion projects such as LIFE and HiPER, the main parameter requirements include: inner radius 6m, fusion reactor power 200MW, ignition frequency 1Hz, etc., the radial distribution and size of the functional areas in the spherical laser inertial fusion cladding are obtained, and a corresponding simplified spherical three-dimensional model is established;

[0033] 2. According to the core design parameters of LIFE and HiPER, the neutron characteristics of the cladding material and the preliminary design structural parameters of the cladding, the Monte Carlo method and the neutron transport program such as OpenMC are used to complete the calculation of the spherical cladding three-dimensional model established in step 1, to obtain the spatial distribution of nuclear heat deposition in the LIFE and HiPER cladding and the overall tritium breeding rate of the cladding, so as to determine the radial preliminary size of the tritium breeding self-cooling area and other functional areas;

[0034] ​3. According to the heat transfer principle of fluid and solid, the initial parameters of the laser etching micro-channel design, such as the flow channel size, coolant flow rate and steel plate thickness, are obtained by using the numerical calculation method of coolant physical properties and convective heat transfer coefficient; then, according to the geometric structure of LIFE and HiPER blanket and the thermal hydraulic characteristics of the blanket material, the thermal hydraulic analysis model of LIFE and HiPER blanket is established by using the CFD program, and based on the first wall surface heat flux density distribution obtained from the core design parameters and combined with the nuclear heat deposition spatial distribution in the laser inertial fusion blanket obtained in step 2, the initial temperature distribution of the LIFE and HiPER blanket is obtained;

[0035] 4. Due to the different core design parameters of LIFE and HiPER and the temperature limit of the blanket material, the applicable blanket structure is different, so multiple calculations are needed to obtain the reasonable interval of the radial size of the functional area in the blanket, i.e. multiple steps 2 and 3 are performed, but the "blanket preliminary design structure parameters" used in the first step 2 need to be changed to the corresponding blanket design structure parameters in the subsequent implementation process, and the reasonable interval of the radial size of the functional area in the blanket that adapts to the laser fusion core design parameters and the temperature limit of the blanket material is obtained after iterative calculation, and in the above multiple calculations, different optimization algorithms such as population algorithm are used to determine the reasonable interval of the radial size of the blanket more quickly, such as: the reasonable thickness interval of the inner partition in the tritium breeding functional area is [5, 8] mm;

[0036] 5. A complete three-dimensional model of the overall blanket is established - the neutron transport program of the Monte Carlo method and the CFD program establish the fine model of neutron transport and thermal hydraulic of the blanket, in which the finite volume method and the Monte Carlo method are used to discretize the partial differential equations of temperature field and neutron transport field respectively, and the grid size obtained by the two methods for the same geometric structure is quite different, especially the Monte Carlo method uses the Boolean operation of geometric bodies to obtain the grid cells, which is less flexible than the grid cells obtained by the finite volume method, so the volume weighted average method is needed to transfer data between grids, and the direct coupling calculation of neutron transport and thermal hydraulic is carried out, and according to the reasonable interval of the radial size of the functional area in the blanket obtained in step 4, the optimized design structure parameters of the blanket are determined combined with the design standards of the laser inertial fusion blanket.

Claims

1. A laser inertial fusion hohlraum, characterized by: The laser inertial fusion blanket is divided into several arc-shaped sub-blankets by equidividing meridians, and each arc-shaped sub-blanket is divided into several blanket modules by equidividing latitudes, wherein one of the blanket modules near the two poles is left empty as an entrance for an external device of the blanket; the functional zones of the blanket modules are divided into a tungsten armor (1), a first wall (2), a tritium breeding self-cooling zone (3), and a back plate (4) from the center of the fusion reaction to the outside, the tungsten armor (1) and the front end first wall (2) are formed by diffusion welding of multiple low-activity ferrite and martensite steel plates, each of which is provided with laser etching micro-channels to ensure the structural strength and improve the cooling efficiency of the supercritical carbon dioxide coolant; the tritium breeding self-cooling zone (3) is made of liquid lithium-lead alloy, and the tritium breeding self-cooling zone (3) is divided into three sub-zones by multiple welding steel plates provided with the laser etching micro-channels; the laser etching micro-channels with high heat exchange efficiency can make full use of the cooling capacity of the supercritical carbon dioxide coolant, effectively control the temperature of the interface between the steel plate and the liquid lithium-lead, reduce the corrosion of the liquid lithium-lead to the structural material of the blanket, and improve the overall service life of the blanket; the back plate (4) is the outermost structure of the blanket, and the inner part directly contacting the liquid lithium-lead alloy is formed by multiple welding steel plates provided with the laser etching micro-channels, and is internally connected with the supercritical carbon dioxide as a coolant to carry away heat, so as to control the temperature of the interface between the back plate and the liquid lithium-lead alloy below the critical corrosion temperature threshold; the outer part of the back plate is formed by low-activity ferrite and martensite steel to improve the overall structural strength of the blanket module, and serves as a support surface for the external device of the blanket.

2. The laser inertial fusion hohlraum of claim 1, wherein: The laser inertial fusion blanket is divided into 24 arc-shaped sub-blankets by equidividing meridians, and each arc-shaped sub-blanket is divided into 9 blanket modules by equidividing latitudes.

3. The method of designing a laser inertial fusion heller of claim 1, wherein: The method comprises the following steps: Step 1: establishing a three-dimensional model of the spherical blanket According to the structure of the laser inertial fusion blanket, the radial distribution and size of the functional zones in the spherical blanket are determined, and a corresponding simplified three-dimensional spherical model is established; Step 2: neutron transport calculation of the spherical blanket According to the design parameters of the laser fusion core, the neutron characteristics of the blanket material, and the preliminary design structural parameters of the blanket, the Monte Carlo method and the neutron transport program are used to complete the calculation of the three-dimensional model of the spherical blanket established in step 1, to obtain the spatial distribution of nuclear heat deposition and the overall tritium breeding rate in the laser inertial fusion blanket, so as to determine the radial preliminary size of the tritium breeding self-cooling zone functional zone; Step 3: thermal-hydraulic calculation of the spherical blanket According to the principles of fluid and solid heat transfer, the numerical calculation method of coolant properties and convective heat transfer coefficient is used to obtain the preliminary design parameters of the laser etching micro-channel, including the flow channel size, coolant flow rate, and steel plate thickness; then, according to the geometric structure of the laser inertial fusion blanket, the thermal-hydraulic characteristics of the blanket material, and the thermal-hydraulic analysis model of the laser inertial fusion blanket established by the CFD program, the preliminary distribution of the material temperature in the laser inertial fusion blanket is obtained based on the first wall surface heat flux density distribution obtained from the core design parameters and the preliminary design parameters of the laser etching micro-channel, and combined with the spatial distribution of nuclear heat deposition obtained in step 2. Step 4: Multi-physical field coupling iterative calculation of spherical blanket Due to the different design parameters of laser fusion core and the temperature limit of blanket material, the applicable blanket structure is different, so multiple calculations are needed to obtain the radial size interval of the functional area in the blanket, that is, steps 2 and 3 are performed multiple times. However, the "blanket preliminary design structure parameters" used in the first step 2 need to be changed to the corresponding blanket design structure parameters in the subsequent implementation process. After iterative calculation, the radial size interval of the functional area in the blanket that adapts to the design parameters of the laser fusion core and the temperature limit of the blanket material is obtained. At the same time, in the process of multiple calculations, different optimization algorithms are used to determine the radial size interval of the functional area in the blanket more quickly. Step 5: Fine three-dimensional blanket optimization design Establish a complete three-dimensional model of the overall blanket---the neutron transport program and CFD program of the Monte Carlo method establish a fine model of neutron transport and thermal-hydraulic in the blanket, use finite volume method for data transmission between grids, perform direct coupling calculation of neutron transport and thermal-hydraulic, and according to the radial size interval of the functional area in the blanket obtained in step 4, combined with the laser inertial fusion blanket design standard, determine the optimization design structure parameters of the blanket.

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