Method for calculating radiation transfer of reactor cavity in laser fusion reactor

Abstract

The invention discloses a reactor cavity radiation transfer calculation method in a laser fusion reactor. The method comprises the following steps: 1, establishing a spherical laser fusion reactor model; 2, spherical reactor cavity shock wave radiation calculation: calculating a shock wave radiation transfer process by using a Lagrange radiation-magnetofluid dynamics code to obtain a xenon radiation power curve; 3, calculating the radiation energy of the first wall of the spherical reactor cavity: averagely loading the residual energy except the direct radiation energy in the first period in the whole period as uniform radiation energy; and 4, carrying out multi-physics field coupling iterative calculation on the spherical cladding, considering that the temperature of the first wall is balanced when the temperature vibration amplitude and the maximum and minimum values do not change any more, and ending radiation transfer calculation on the reactor cavity of the laser fusion reactor. According to the method, the radiation energy and the radiation power passing through the first wall of the laser fusion reactor under different reactor cavity sizes, different pellet energy and different xenon densities can be calculated, and reference is provided for the design of the laser fusion reactor pellet, the laser and the whole reactor.

Description

Technical Field

[0001] The present invention relates to the technical field of laser fusion reactor radiation transfer, and in particular to a method for calculating reactor cavity radiation transfer in a laser fusion reactor. Background Art

[0002] A laser fusion reactor consists of a spherical reactor cavity. A target pellet is injected into the center of the cavity, where it undergoes a laser-driven implosion reaction. The energy generated by the fusion of the target pellet is primarily released in the form of X-ray radiation and neutrons, which first reach the first wall and are then deposited in the reactor cavity blanket. Some of these neutrons react with the tritium breeder, while the remaining neutrons and radiation are deposited in the blanket. The heat generated is dissipated through the blanket's cooling system.

[0003] Unlike magnetic confinement fusion, in laser fusion reactors, the energy release of the target capsule implosion is a periodic, strong transient process. The target capsule energy is released in nanoseconds and repeated according to the frequency of the reaction. This causes the first wall to be subjected to very severe transient thermal loads and may cause material damage, in which radiation energy plays a dominant role.

[0004] Typically, to reduce the peak power of radiation, xenon gas is used to absorb some of the transient radiation energy, reducing the instantaneous power and flattening the power peak to protect the first wall. During this process, the radiation power is affected by the target energy, reaction frequency, xenon gas density, and reactor cavity size. The target energy and reaction frequency affect both the target and laser design, while the reactor cavity size affects the overall reactor design. Excessively high xenon gas density can also affect laser propagation during ignition, reducing energy transmission efficiency.

[0005] Existing research focuses on radiation transfer within the reactor cavity, making it difficult to establish a direct logical relationship with laser fusion reactors during ignition and device research. Therefore, a comprehensive and systematic analysis is needed to obtain more accurate reactor-level radiation transfer characteristics. Simulating reactor-level results can provide a reference for current ignition and device research. Summary of the Invention

[0006] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a method for calculating the radiation transfer in the reactor cavity of a laser fusion reactor, which provides a reference for the design of the target capsule, laser and the entire reactor of the laser fusion reactor.

[0007] The present invention adopts the following technical solutions to achieve the above-mentioned purpose:

[0008] A method for calculating radiation transfer in a laser fusion reactor cavity comprises the following steps:

[0009] Step 1: Build a spherical laser fusion reactor model

[0010] Based on the structure and specific design requirements of the laser fusion reactor, the xenon density in the spherical cavity of the laser fusion reactor and the radial material distribution and size of each functional area of ​​the blanket are determined. The reaction frequency and the total energy released by the target pellet are determined, and a spherical laser fusion reactor model is established.

[0011] Step 2: Calculation of shock wave radiation in the spherical reactor cavity

[0012] The shock wave radiation transfer process was calculated using a Lagrangian radiation-magnetohydrodynamics code. Radiation energy was loaded into a core sphere with a radius of 0.1 cm. A Gaussian function was used to simulate the transfer of radiation energy throughout the laser fusion reactor cavity. The radiation energy of different target pellets accounted for 15% to 20% of the total energy of the target pellet, with the larger value of 20% being taken. The radiation energy and power passing through the first wall, or radiation boundary, were calculated, and the radiation power curve was then derived.

[0013] Step 3: Calculation of radiation energy of the first wall of the spherical reactor cavity

[0014] According to the xenon radiation power curve obtained in step 2, the instantaneous radiation power peak occurs in the first few milliseconds, indicating that the direct radiation energy is mainly concentrated in the first few milliseconds. In the first few calculation cycles, the xenon absorbs some of the radiation energy and continuously heats up. The radiation energy passing through the boundary is lower than the loaded radiation energy, and the secondary radiation power is low. After several cycles of iterative calculation, the radiation energy passing through the boundary equals the loaded energy, and equilibrium is reached. The xenon temperature remains constant, and the secondary radiation power also remains constant. The secondary radiation power accounts for the majority of the radiation energy. Comparing the first radiation cycle with the stabilization cycle, the peak radiation power after equilibrium is slightly higher than the peak radiation power of the first cycle. The peak radiation power of the first cycle is the direct radiation power, while the peak radiation power after equilibrium is the direct radiation power plus the secondary radiation power. Considering that the large direct radiation power value and the short loading time are the main causes of the first wall temperature oscillation, to simplify the calculation, the energy remaining after deducting the direct radiation energy in the first cycle is averaged over the entire cycle as uniform radiation energy. This energy deviates slightly from the balanced secondary radiation energy, and the overall error is acceptable. Using the above method, the complete radiation energy output can be approximately divided into two parts: the instantaneous radiation power at the initial stage of the calculation and the uniform radiation power over the entire calculation period. These two parts represent the direct radiation energy passing through the reactor cavity after the implosion reaction and the secondary radiation energy released by the heated xenon gas.

[0015] Step 4: Spherical cladding multi-physics coupling iterative calculation

[0016] Combined with the first wall radiation energy data obtained in step 3, multiphysics coupling software is used to couple neutron deposition heat to calculate the first wall temperature. Neutron deposition heat is calculated using a neutron transport program using the Monte Carlo method. Neutron deposition heat is uniformly applied within 1 nanosecond. The radiation energy loading method uses the following method: the peak radiation power of the first cycle is used as the power during the loading period, the time when the radiation power peak occurs is used as the loading time, and the uniform radiation energy is applied evenly over the entire cycle. Solid heat transfer is calculated using the Fourier heat conduction model, supercritical carbon dioxide using the turbulence model, and liquid lithium-lead using the laminar flow model. To calculate the temperature of the first wall when it stabilizes, iterative calculations are required. When the temperature oscillation amplitude and maximum and minimum values ​​no longer change, the first wall temperature is considered to have reached equilibrium, and the laser fusion reactor cavity radiation transfer calculation is concluded.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1) The method of the present invention can calculate the radiation energy and radiation power passing through the first wall of a laser fusion reactor under different reactor cavity sizes, different target pellet energies, and different xenon gas densities.

[0019] 2) Based on multiple programs such as the Lagrangian radiation-magnetohydrodynamics code, the Monte Carlo neutron transport program, and multi-physics field coupling software, this paper proposes a systematic calculation method for the radiation transfer in the core cavity of a laser fusion reactor, providing a reference for the design of laser fusion reactor target capsules, lasers, and the entire reactor.

[0020] 3) The present invention fully considers the characteristics of the laser inertial confinement fusion process and the characteristics of product release, and considers the radiation energy and neutrons released by the target capsule separately. The Lagrangian radiation-magnetohydrodynamics code is used to calculate the radiation shock wave transfer process, and the Monte Carlo neutron transport program is used to calculate the deposition heat of neutrons in the blanket. Different loading methods are used for radiation energy and neutron deposition heat. Multi-physics field coupling software is used to couple the laser fusion reactor blanket model to calculate the temperature oscillation of the reactor first wall, which provides a reference for predicting first wall damage and laser reactor blanket design.

[0021] 4) The present invention adopts a multi-physics field coupling method to study the radiation transfer in the laser fusion reactor cavity, and provides a reliable calculation method for the radiation transfer in the laser fusion reactor cavity.

[0022] In summary, the present invention designs a method for calculating cavity radiation transfer in a laser fusion reactor and proposes the corresponding calculation steps in detail. It can establish a radiation transfer calculation process based on Lagrangian radiation-magnetohydrodynamics code, Monte Carlo neutron transport program, multi-physics field coupling software, etc., and establishes a systematic analysis framework for cavity radiation transfer in laser fusion reactors, providing a reference for the design of laser fusion reactor target capsules, lasers, and the entire reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the blanket structure of a laser inertial fusion reactor for application of the calculation method of reactor cavity radiation transfer;

[0024] Figure 2 This is a flow chart of the calculation method for cavity radiation transfer in a laser fusion reactor. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] The laser fusion reactor cavity calculated by the present invention is a spherical structure, which is filled with xenon gas. The target pellet at its center undergoes periodic implosion reactions, and the energy generated by the fusion is then released mainly in the form of X-ray radiation and neutrons. During the entire process of radiation energy transfer, X-rays are constantly reflected and absorbed when penetrating the xenon gas. Only a portion of the energy can penetrate the xenon gas and reach the first wall. The absorbed energy is transferred and interacted in the cavity in the form of radiation shock waves and secondary radiation, while the neutron energy is evenly deposited in the entire cavity blanket. The formation of the radiation shock wave begins with the deposition of laser energy on the target pellet or the surrounding medium. The rapid deposition of energy leads to local high temperature and high pressure, which in turn drives the shock wave to propagate outward. The blanket of the laser fusion reactor adopts a double-cooled liquid blanket structure of supercritical carbon dioxide and liquid lithium-lead. The temperature oscillation of the first wall under the action of radiation heat and neutron deposition heat is calculated. The model of the laser fusion reactor cavity and its external double-cooled liquid blanket of supercritical carbon dioxide and liquid lithium-lead is shown as follows. Figure 1 As shown, the target capsule undergoes periodic implosion at the center of the laser fusion reactor, and the reactor cavity from the center to the first wall is filled with xenon gas. The cladding material from the first wall to the outside is as shown in Figure 1Shown in order are: first wall tungsten 1, low-activity ferrite and marrite steel 2, supercritical carbon dioxide 3, low-activity ferrite and marrite steel 2, liquid lithium-lead alloy 4 and low-activity ferrite and marrite steel 2; the radiation heat calculation uses the Lagrangian radiation-magnetohydrodynamics code to load the radiation energy into the core sphere, and then simulates the process of radiation transmission in the entire reactor cavity, taking the first wall as the radiation boundary, and calculating the radiation energy and radiation power passing through the boundary; the neutron deposition heat calculation uses the neutron transport program of the Monte Carlo method to calculate the deposition heat generated by neutrons in the entire blanket; then, through the multi-physics field coupling method, the temperature oscillation of the first wall is obtained through continuous iterative calculation.

[0027] like Figure 2 As shown, the steps of the laser inertial fusion reactor cavity radiation transfer calculation method of the present invention are as follows:

[0028] 1. According to the structure and specific design requirements of the laser fusion reactor, the xenon density in the spherical reactor cavity of the laser fusion reactor and the radial material distribution and size of each functional area of ​​the blanket are determined, the reaction frequency and the total energy released by the target pellet are determined, and a spherical laser fusion reactor model is established. In this embodiment, a 200MW power laser fusion reactor is used as an example to construct a supercritical carbon dioxide and liquid lithium-lead dual-cooled liquid blanket reactor cavity. Figure 1 As shown. The reactor cavity radius is 3m and the xenon density is 6mg / cm 3 .

[0029] 2. Use the Lagrangian radiation-magnetohydrodynamics code to calculate the shock wave radiation transfer process. The radiation energy is loaded into a core sphere with a radius of 0.1 cm. The energy loading uses a Gaussian function to simulate the process of radiation energy transfer throughout the laser fusion reactor cavity. The radiation energy of different target pellets usually accounts for 15% to 20% of the total energy of the target pellet. The larger value of the target pellet radiation energy is 20% of the total energy of the target pellet. In this embodiment, the target pellet energy is 15MJ, the target pellet radiation energy is 3MJ, and the reaction frequency is 13.3Hz. The radiation energy and radiation power passing through the first wall, i.e., the radiation boundary, are calculated, and then the radiation power curve is obtained.

[0030] 3. According to the radiation power curve obtained in step 2, the radiation energy of the first cycle is primarily concentrated within the initial 2ms, with a peak power of 177.77MW. This portion of energy is 0.123MJ, accounting for 4.1% of the target pellet's radiation energy. The radiation after equilibrium maintains the same trend as the first cycle, but the subsequent secondary radiation output reaches the 30MW level, with a peak power of 190.42MW, slightly greater than the first cycle due to the superposition of the secondary radiation output. The remaining 95.9% of the energy from the first cycle is averaged over the entire cycle as uniform radiation energy, resulting in an average power of 38MW, less than 5% deviation from the equilibrium secondary radiation. The boundary deposition energy calculated using this method at 2ms is 0.217MJ, which deviates by 4% from the iterative calculation of 0.226MJ, an acceptable overall error. Using the above method, the complete radiation energy output can be approximately divided into two parts: the instantaneous radiation power at the initial stage of the calculation and the uniform radiation power over the entire calculation period. These two parts represent the direct radiation energy passing through the reactor cavity after the implosion reaction and the secondary radiation energy released by the heated xenon gas.

[0031] 4. Combine the first wall radiation energy data obtained in step 3 with the neutron deposition heat data using multiphysics coupling software to calculate the first wall temperature. Neutron deposition heat is calculated using a Monte Carlo neutron transport program. Neutron deposition heat is uniformly applied over a 1 ns period. Radiation energy loading is performed using the peak radiation power of the first cycle as the power during loading, the time at which the peak occurs as the loading time, and uniform radiation energy is applied evenly over the entire cycle. Solid heat transfer is calculated using the Fourier heat conduction model, supercritical carbon dioxide using the turbulence model, and liquid lithium-lead using the laminar flow model. To calculate the first wall's stable temperature, iterative calculations are required. When the temperature oscillation amplitude and maximum and minimum values ​​no longer change, the first wall temperature is considered to have reached equilibrium, and the laser fusion reactor cavity radiation transfer calculation concludes.

Claims

1. A method for calculating cavity radiation transfer in a laser fusion reactor, characterized by: The steps include: Step 1: Build a spherical laser fusion reactor model Based on the structure and specific design requirements of the laser fusion reactor, the xenon density in the spherical cavity of the laser fusion reactor and the radial material distribution and size of each functional area of ​​the blanket are determined. The reaction frequency and the total energy released by the target pellet are determined, and a spherical laser fusion reactor model is established. Step 2: Calculation of shock wave radiation in the spherical reactor cavity The shock wave radiation transfer process was calculated using a Lagrangian radiation-magnetohydrodynamics code. Radiation energy was loaded into a core sphere with a radius of 0.1 cm. A Gaussian function was used to simulate the transfer of radiation energy throughout the laser fusion reactor cavity. The radiation energy of different target pellets accounted for 15% to 20% of the total energy of the target pellet, with the larger value of 20% being taken. The radiation energy and radiation power passing through the first wall, i.e., the radiation boundary, are calculated, and then the radiation power curve is obtained; Step 3: Calculation of radiation energy of the first wall of the spherical reactor cavity According to the radiation power curve obtained in step 2, the instantaneous radiation power peak appears in the initial few milliseconds, which indicates that the direct radiation energy is mainly concentrated in the initial few milliseconds. In the first few cycles of calculation, the xenon gas absorbs part of the radiation energy and continues to heat up. The radiation energy passing through the boundary is lower than the loaded radiation energy, and the secondary radiation power is low. After several cycles of iterative calculation, the radiation energy passing through the boundary is equal to the loaded energy. At this time, the equilibrium state is reached, the xenon gas temperature remains constant, the secondary radiation power also remains constant, and the secondary radiation energy accounts for the main part of the radiation energy. Comparing the first radiation cycle with the stable cycle, the peak radiation power after equilibrium is higher than that of the first cycle. The peak radiation power is due to the fact that the peak radiation power in the first cycle is the direct radiation power, while the peak radiation power after equilibrium is the sum of the direct radiation power and the secondary radiation power. Considering that the direct radiation power is large and the loading time is short, it is the main cause of the first wall temperature oscillation. To simplify the calculation, the energy remaining after deducting the direct radiation energy in the first cycle is evenly loaded over the entire cycle as uniform radiation energy. The complete radiation energy output is approximately divided into two parts: the instantaneous radiation power at the initial stage of the calculation and the uniform radiation power over the entire cycle. These two parts represent the direct radiation energy that passes through the reactor cavity after the implosion reaction and the secondary radiation energy released by the heated xenon gas, respectively. Step 4: Spherical cladding multi-physics coupling iterative calculation Combined with the first wall radiation energy data obtained in step 3, multi-physics coupling software is used to couple the neutron deposition heat to calculate the first wall temperature, where the neutron deposition heat is calculated using a neutron transport program using the Monte Carlo method; the neutron deposition heat is uniformly loaded within 1 ns; the radiation energy loading is performed as follows: the peak radiation power of the first cycle is used as the power during the loading period, and the time when the radiation power peak occurs is used as the loading time. The uniform radiation energy is loaded evenly over the entire cycle; Solid heat transfer is calculated using the Fourier thermal conductivity model, supercritical carbon dioxide using the turbulence model, and liquid lithium-lead using the laminar flow model. To calculate the temperature of the first wall when it stabilizes, an iterative calculation is required. When the temperature oscillation amplitude and the maximum and minimum values ​​no longer change, the first wall temperature is considered to have reached equilibrium, and the laser fusion reactor cavity radiation transfer calculation is concluded.

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