Method for stress test and dangerous area assessment of fusion device intermittent heat source heat storage tank

Abstract

The application discloses a stress test and dangerous area evaluation method for an intermittent heat source storage tank of a fusion device, belongs to the technical field of performance detection of core equipment of an energy storage system of a fusion device, and aims at liquid level periodic change and thermal-mechanical coupling problems caused by intermittent operation of a fusion reactor. The application reproduces a storage tank operation process by simulating liquid level circulation and thermal loss boundary conditions under actual working conditions. Strains are monitored by using a layered point distribution mode to obtain stress change rules, maximum stress values and amplitudes in a complete period. On this basis, strength and fatigue dangerous areas are identified, and dynamic migration characteristics of the dangerous areas with a liquid level and a temperature interface are revealed. The application solves the problem that existing technologies cannot reflect dynamic coupling stress and dangerous area change, and provides reliable data support for structural optimization design, strength checking and fatigue life analysis of the fusion storage tank.

Description

Technical Field

[0001] This invention belongs to the technical field of core equipment performance testing of fusion device energy storage systems, specifically relating to a method for stress testing and hazardous area assessment of intermittent heat source storage tanks in fusion devices. Background Technology

[0002] With the development of controlled nuclear fusion energy technology, fusion reactors, as advanced energy devices with high energy density, low carbon emissions, and high safety, are gradually moving from the physical experiment stage to the engineering demonstration and commercial application stage. In fusion reactor energy utilization systems, the high-grade thermal energy generated by fusion plasma needs to be recovered and utilized through energy conversion systems. Among these systems, energy storage systems, as a key intermediate link connecting the heat source and downstream power generation systems, can resolve the contradiction between the intermittent operation of the fusion reactor and the power generation system's demand for a stable heat source, thus helping to improve system stability and reliable operational lifespan.

[0003] The thermal storage tank is a core component of existing fusion reactor thermal storage systems. Compared to conventional tanks, fusion reactor thermal storage tanks exhibit significant periodic liquid level fluctuations. During fusion reactor operation, high-temperature molten salt continuously enters the tank, gradually increasing the liquid level. During periods of reactor shutdown, the tank continuously supplies heat, causing the liquid level to gradually decrease. With the periodic alternation of reactor operation and shutdown, the tank liquid level continuously cycles between high and low levels. This periodic change in liquid level not only leads to continuous variations in the hydrostatic pressure on the tank wall, resulting in changes in mechanical stress, but also alters the temperature distribution on the tank wall. As the liquid level rises and falls, the contact area between the high-temperature molten salt and the tank wall changes continuously. The area below the molten salt level is heated by the high-temperature molten salt, while the area above the level is mainly affected by the free flow of air and heat dissipation from the environment. Due to the combined effects of periodic cold air intrusion and wall heat loss unique to thermal storage tanks used in fusion reactors, the wall temperature above the liquid level is significantly lower than that below the liquid level. Therefore, the temperature interface on the tank wall continuously changes with the liquid level, resulting in a dynamic migration of the temperature interface. This leads to periodic changes in temperature stress, a phenomenon unique to thermal storage tanks used in fusion reactors. Specifically, as the liquid level decreases, the temperature interface layer on the sidewall migrates downwards, and the temperature difference between the upper and lower parts of the tank wall can reach as high as 138°C, causing severe thermal stress. Consequently, the temperature interface will migrate at different liquid levels.

[0004] Therefore, the actual stress state of the fusion reactor thermal storage tank wall is not solely determined by the pressure stress caused by liquid level changes, nor by the temperature stress generated by overall heating or cooling. Instead, it is a thermo-mechanical coupled stress formed by the combined effects of hydrostatic pressure stress caused by periodic liquid level changes and temperature stress generated by the dynamic migration of the temperature interface under heat loss. Since the variation patterns of these two types of stresses during operation are not consistent, the location of the maximum stress on the storage tank wall and the corresponding location of the stress variation amplitude may not be the same, leading to dynamic changes in the hazardous area with liquid level changes. Because the temperature interface on the fusion reactor thermal storage tank wall continuously changes with liquid level, there are significant differences in wall temperature at different heights at the same time, and the temperature at the same test point continues to change during operation. The elastic modulus and Poisson's ratio of the storage tank material both change with temperature. If fixed material parameters are used to calculate stress based on strain, it will be difficult to accurately reflect the actual stress state of the storage tank wall, thus affecting the accuracy of hazardous area identification and strength and fatigue assessment results.

[0005] During long-term operation, the walls of the thermal storage tank will experience repeated stress cycles under the aforementioned periodic thermo-mechanical coupling effects, making them prone to fatigue damage and crack propagation. In severe cases, this could lead to leaks in the thermal storage tank, impacting the safe operation of the fusion reactor energy storage and power generation systems. Therefore, accurately obtaining the stress variation patterns and hazardous area distribution characteristics of the fusion reactor thermal storage tank during cyclic operation is of great significance for optimizing the tank's structural design, assessing stress intensity, and analyzing fatigue life.

[0006] Existing technologies involving stress testing of thermal storage tanks include, for example, Chinese patent application CN202411224701.3, which discloses a molten salt storage tank testing device and method, and Chinese patent application CN201610982991.7, which discloses a pre-cooling temperature stress testing system for LNG storage tanks used for strain gauge installation. These technologies primarily target tank stress testing under specific heating or cooling conditions. Temperature changes are actively applied through the overall heating or cooling process, without addressing the dynamic temperature interface changes resulting from the combined effects of cyclical liquid level changes and heat loss. Therefore, they cannot reflect the formation mechanism and actual change process of thermo-mechanical coupling stress in fusion reactor thermal storage tanks. Furthermore, existing tank stress testing is only related to the pressure caused by the liquid level, with the danger zone fixed near the bottom. Test points are typically arranged according to fixed danger areas, assuming the danger zone remains constant throughout operation. Strength or fatigue assessment is based solely on the maximum stress or stress change amplitude corresponding to the fixed test points. However, for fusion reactor thermal storage tanks, the thermo-mechanical coupling stress distribution on the tank wall continuously changes during operation due to hydrostatic pressure variations caused by periodic liquid level changes and alterations in the temperature interface. Critical areas may also dynamically change. Current technologies cannot obtain the thermo-mechanical coupling stress variation patterns of fusion reactor thermal storage tanks throughout a complete operating cycle, nor can they identify the dynamic changes in critical areas caused by liquid level and temperature interface variations. Furthermore, existing stress calculations typically use fixed material parameters for conversion, failing to consider the impact of continuous temperature changes at various test points on the material's mechanical properties caused by periodic liquid level changes. Therefore, it is difficult to accurately obtain the true stress distribution on the tank wall under dynamic temperature fields.

[0007] Therefore, there is an urgent need to provide a method for stress testing and hazardous area assessment of thermal storage tanks suitable for intermittent heat source operation of fusion devices. By simulating the cyclical changes in liquid level and real heat loss conditions during the actual operation of a fusion reactor, a dynamic thermal boundary consistent with the actual operation of the fusion reactor is constructed, so that the temperature interface of the thermal storage tank wall changes dynamically with the liquid level. The real-time temperature of each test point is collected simultaneously, and the thermo-mechanical coupling stress under the dynamic temperature field of the thermal storage tank is calculated in combination with the material mechanical parameters at the corresponding temperature. The thermo-mechanical coupling stress change law and the dynamic change characteristics of the hazardous area of ​​the thermal storage tank during the complete operation cycle are accurately obtained, providing reliable data support for the optimized design of thermal storage tanks for fusion devices. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a method for stress testing and hazardous area assessment of the thermal storage tank of a fusion reactor intermittent heat source. Addressing the stress changes caused by the periodic changes in the liquid level of the thermal storage tank during the intermittent operation of a fusion reactor, and the temperature stress changes caused by the alteration of the temperature interface, this method simulates the actual operation and shutdown conditions of the fusion reactor to realistically reproduce the characteristics of the periodic changes in the liquid level and the temperature interface changes caused by heat loss, thereby obtaining the thermo-mechanical coupling stress variation law of the thermal storage tank within a complete operating cycle. Based on the characteristics of stress changes at different locations over time and with liquid level, the location and dynamic variation law of the hazardous area of ​​the thermal storage tank are identified, providing data support for the structural optimization design of the thermal storage tank of the fusion reactor.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for stress testing and hazardous area assessment of intermittent heat source storage tanks in fusion devices includes the following steps:

[0011] Step 1: The molten salt is transported to the thermal storage tank to reach the minimum liquid level of the thermal storage tank. After the temperature stabilizes, the insulation and ventilation are adjusted to maintain the heat loss rate within the design operating range, thereby constructing the initial wall temperature and heat loss rate consistent with the actual operation of the fusion reactor, so that the thermal storage tank wall forms a temperature interface that changes with the liquid level.

[0012] Step 2: Turn off the heater of the thermal storage tank, fill the thermal storage tank with molten salt according to the target flow rate to the highest liquid level of the storage tank to complete the thermal storage, and then discharge the molten salt to the lowest liquid level to complete the heat release; set up a test group including strain-temperature combined test points to simultaneously collect strain data, temperature data and liquid level data;

[0013] Step 3: Calculate the stress value by combining the temperature data of each strain-temperature combination test point, and establish a curve of thermo-mechanical coupling stress changing with time and liquid level;

[0014] Step 4: Obtain the maximum stress value, minimum stress value, and stress change amplitude based on the curve, and evaluate the structural strength and fatigue damage characteristics of the thermal storage tank respectively.

[0015] Step 5: Compare the maximum stress value and stress change amplitude of each test group to determine the strength danger zone and fatigue danger zone;

[0016] Step 6: Based on the assessment results of the combined strength hazard area and fatigue hazard area, determine the critical hazard area or fatigue control hazard area of ​​the thermal storage tank;

[0017] Step 7: Statistically analyze the location changes of the intensity hazard zone and fatigue hazard zone during the complete operating cycle, and obtain the dynamic change characteristics of the hazard zone with the liquid level and temperature interface.

[0018] Step 8: Determine the main dangerous areas based on the maximum stress value, stress change amplitude, and occurrence time of the dangerous area.

[0019] Beneficial effects:

[0020] 1. This invention proposes for the first time a method for stress testing and hazardous area assessment of thermal storage tanks applicable to intermittent heat source operation in fusion devices. By simulating the alternating operation mode of the fusion reactor during its operation and intermittent periods, the cyclical change process of the temperature interface migration on the wall of the thermal storage tank can be realistically reproduced. This allows for the acquisition of the stress variation law, maximum stress value, and maximum stress variation amplitude of the thermal storage tank within a complete operating cycle, providing a reliable basis for strength verification and fatigue damage analysis of the thermal storage tank.

[0021] 2. This invention fully considers the dynamic changes in the temperature interface under heat loss during the periodic changes in the liquid level of the fusion reactor's thermal storage tank. As the liquid level rises and falls, the contact area between the high-temperature molten salt and the tank wall continuously changes, causing the wall temperature interface to constantly change. This, along with the hydrostatic pressure caused by the liquid level change, forms a thermo-mechanical coupled stress. By constructing thermal boundary conditions consistent with the actual operation of a fusion reactor, the stress change process formed by the combined action of mechanical and thermal stresses on the tank wall can be accurately reflected. Stress calculations are performed based on the material mechanical parameters at the corresponding temperature matching the real-time temperature at each test point, allowing for a more accurate reflection of the coupling effect of mechanical and thermal stresses. This improves the accuracy of stress calculations and hazardous area assessments of the thermal storage tank under dynamic temperature field conditions.

[0022] 3. This invention addresses the periodic fluctuations in the interface between liquid level and temperature in fusion reactor thermal storage tanks by proposing a layered testing method based on the liquid level variation range and a dynamic identification method for hazardous areas. Based on the lowest and highest liquid levels and their fluctuation ranges in the storage tank, multiple test groups are set up along the height direction within the liquid level variation coverage area. Stress changes are simultaneously monitored in conjunction with the connection areas of the bottom plate and side walls to obtain the stress distribution characteristics of the storage tank at different operating stages. By comparing the stress change patterns of each test group during heat storage and release processes, the location and dynamic changes of hazardous areas are identified, providing a technical basis for the optimized design of the thermal storage tank structure. Attached Figure Description

[0023] Figure 1 This is a system structure diagram of a method for stress testing and hazardous area assessment of an intermittent heat source storage tank for a fusion device according to the present invention.

[0024] The attached figures are labeled as follows: 1-Heat storage tank, 2-Storage equipment, 3-First pump, 4-First valve, 5-Second pump, 6-Second valve, 7-Heat storage tank heater, 8-Molten salt storage equipment heater, 9-Pipeline electric heat tracing, 10-Insulation layer, 11-Bottom insulation structure, 12-Base and ventilation mechanism, 13-Strain-temperature combination test point, 14-First thermocouple, 15-Second thermocouple, 16-Third thermocouple, 17-Level gauge, 18-First heat flow meter, 19-Second heat flow meter, 20-First mass flow meter, 21-Second mass flow meter. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0026] like Figure 1 As shown, the system involved in the stress testing and hazardous area assessment method of the intermittent heat source storage tank of a fusion device according to the present invention includes a heat storage tank 1, a storage device 2, a first pump 3, a first valve 4, a second pump 5, a second valve 6, a heat storage tank heater 7, a molten salt storage device heater 8, an electric heat tracing pipe 9, an insulation layer 10, a bottom insulation structure 11, a base and ventilation mechanism 12, a strain-temperature combination test point 13, a first thermocouple 14, a second thermocouple 15, a third thermocouple 16, a level gauge 17, a first heat flow meter 18, a second heat flow meter 19, a first mass flow meter 20, and a second mass flow meter 21.

[0027] The outlet of storage device 2 is connected to the inlet of the first pump 3, the outlet of the first pump 3 is connected to the inlet of the first valve 4, the outlet of the first valve 4 is connected to the inlet of the thermal storage tank 1, the outlet of the thermal storage tank 1 is connected to the inlet of the second pump 5, the outlet of the second pump 5 is connected to the inlet of the second valve 6, and the outlet of the second valve 6 is connected to the inlet of storage device 2.

[0028] A level gauge 17 is installed on the side wall of the thermal storage tank 1 to measure the liquid level of the thermal storage tank 1; a first thermocouple 14 is installed on the storage device 2 with its probe extending into the interior of the storage device 2 to measure the temperature of the molten salt inside the storage device 2; a second thermocouple 15 is installed on the side wall of the thermal storage tank 1 to measure the temperature of the side wall surface of the thermal storage tank 1; and a third thermocouple 16 is installed on the bottom plate of the thermal storage tank 1 to measure the temperature of the bottom plate of the thermal storage tank.

[0029] The first valve 4 is installed on the pipeline between the outlet of the first pump 3 and the inlet of the thermal storage tank 1, and the second valve 6 is installed on the pipeline between the outlet of the second pump 5 and the inlet of the storage device 2. Both are one-way regulating valves used to control the flow direction of the molten salt medium.

[0030] A heater 7 is installed on the top of the thermal storage tank 1 to heat the internal medium of the molten salt storage tank. A heater 8 is installed on the storage equipment 2 to heat the internal medium of the storage equipment 2. An electric heating tracing device 9 is installed on the outer surface of the connecting pipe between the inlet and outlet of the thermal storage tank 1 and the storage equipment 2 to heat the pipe. An insulation layer 10 is installed on the side wall and top of the thermal storage tank 1 to insulate the internal medium. A bottom insulation structure 11 is installed at the bottom of the thermal storage tank 1 to insulate the internal medium. A base and ventilation mechanism 12 is installed below the bottom insulation structure 11 to support the thermal storage tank 1 and adjust the heat dissipation rate at the bottom.

[0031] The first heat flow meter 18 is installed on the outer surface of the insulation layer of the side wall of the heat storage tank and is used to measure the heat loss of the side wall of the heat storage tank; the second heat flow meter 19 is installed on the outer surface of the insulation structure at the bottom of the heat storage tank and is used to measure the heat loss of the bottom plate of the heat storage tank.

[0032] The first mass flow meter 20 is installed on the pipeline between the outlet of the storage device 2 and the inlet of the thermal storage tank 1 to measure the mass flow rate of molten salt flowing into the thermal storage tank 1; the second mass flow meter 21 is installed on the pipeline between the outlet of the thermal storage tank 1 and the inlet of the storage device 2 to measure the mass flow rate of molten salt flowing out of the thermal storage tank 1.

[0033] Figure 1 In the figure, Q1 is the flow rate measured by the first heat flow meter 18, Q2 is the flow rate measured by the second heat flow meter 19, and T2 is the temperature measured by the second thermocouple 15.

[0034] Based on this, the present invention provides a method for stress testing and hazardous area assessment of intermittent heat source storage tanks in fusion devices. This method is used for stress testing and hazardous area assessment of intermittent heat source storage tanks in fusion devices, realistically simulating the periodic changes in liquid level and heat loss of the storage tank under intermittent operation conditions of the fusion reactor. It obtains the stress change pattern of the storage tank within a complete operating cycle and identifies the dynamic change characteristics of hazardous areas, including:

[0035] Step 1: Turn on the molten salt storage device heater 8, pipeline electric heat tracing 9, and heat storage tank heater 7. Set the heating temperature to the fusion reactor thermal storage system storage temperature Th. When the molten salt inside the storage device 2 melts and the temperature T1 reaches Th, turn on the first pump 3 and the first valve 4. The molten salt is transported from the storage device 2 to the thermal storage tank 1 until the liquid level L1 inside the thermal storage tank reaches the lowest liquid level under the actual operating conditions of the thermal storage tank. Then turn off the first pump 3 and the first valve 4. After the temperature of the second thermocouple 15 at the temperature measuring point on the side wall of the thermal storage tank and the third thermocouple 16 at the temperature measuring point on the bottom plate of the thermal storage tank stabilizes, measure the heat loss rate of the side wall and the bottom plate of the thermal storage tank respectively through the first heat flow meter 18 and the second heat flow meter 19. By adjusting the thickness of the insulation layer 10 and the forced ventilation rate at the bottom of the thermal storage tank, maintain the heat loss rate of the side wall and the bottom plate of the thermal storage tank within the design operating conditions of the thermal storage tank, thereby simulating the side wall temperature interface change process during the actual operation of the fusion reactor thermal storage tank. That is, by establishing the initial wall temperature and heat loss rate consistent with the actual working conditions, and keeping the inlet and outlet medium temperature and flow rate consistent with the actual working conditions, the temperature interface change process of the sidewall is simulated.

[0036] Step 2: Turn off the heater 7 of the thermal storage tank and begin the thermal stress test. Turn on the first pump 3 and the first valve 4, and control the opening of the first valve 4 so that the molten salt medium flows into the thermal storage tank 1 at the target mass flow rate M1. During the thermal storage process, the wall strain and wall temperature of the thermal storage tank at the corresponding positions are measured simultaneously through the strain-temperature combination test points 13 arranged on the thermal storage tank 1. The strain value, wall temperature and thermal storage tank liquid level data of each strain-temperature combination test point 13 are recorded simultaneously at one-minute intervals using a data acquisition instrument.

[0037] At time t1 during the fusion reactor's operation, the liquid level L1 inside the thermal storage tank reaches its highest level under actual operating conditions. At time t1, the first pump 3 and the first valve 4 are closed, while the second pump 5 and the second valve 6 are opened. The opening degree of the second valve 6 is controlled to allow the molten salt medium to flow into the storage device 2 at the target mass flow rate M2.

[0038] At time t1+t2, the liquid level L1 inside the thermal storage tank reaches the lowest level under actual operating conditions, and t2 is the fusion reactor interval. The wall strain and wall temperature at the corresponding location are simultaneously measured using strain-temperature combined test point 13; the strain value, wall temperature, and thermal storage tank liquid level data at each strain-temperature combined test point 13 are simultaneously recorded at one-minute intervals using a data acquisition instrument.

[0039] Preferably, the strain-temperature combined test points 13 are arranged in a layered layout based on the liquid level change range:

[0040] At least three test groups are arranged along the height direction within the liquid level fluctuation coverage area on the side wall of the thermal storage tank, namely the first test group, the second test group, and the third test group, corresponding to the lowest liquid level area, the middle liquid level area, and the highest liquid level area, respectively. The first test group, the second test group, and the third test group are arranged at different height positions within the liquid level fluctuation range. Each test group has no less than 4 strain-temperature combination test points, which are evenly arranged along the circumference at the same height and are all arranged on the outer surface of the side wall of the thermal storage tank.

[0041] At least four test groups are arranged at the large fillet weld connecting the sidewall and bottom plate of the thermal storage tank: the fourth test group, the fifth test group, the sixth test group, and the seventh test group. The fourth test group is located at the inner fillet weld, the fifth test group is located at the outer fillet weld, the sixth test group is located on the inner side of the thermal storage tank sidewall adjacent to the fillet weld, and the seventh test group is located on the inner side of the thermal storage tank bottom plate adjacent to the fillet weld. Each test group has no fewer than four strain-temperature combination test points, evenly distributed along the circumference at the same height.

[0042] At least two test groups, namely the eighth test group and the ninth test group, are arranged on the bottom plate of the thermal storage tank. The eighth test group is located on the central ring of the bottom plate, and the diameter of the central ring is half the diameter of the thermal storage tank. The ninth test group is located in the midpoint area of ​​the bottom plate. Each test group has no less than 4 strain-temperature combination test points, which are evenly distributed along the circumference and arranged on the upper surface of the bottom plate of the thermal storage tank.

[0043] In strain-temperature combined test point 13, strain gauges and thermocouples are installed at the same measurement location to achieve synchronous measurement of wall strain and wall temperature, providing a data foundation for dynamic thermo-mechanical coupled stress calculation. High-temperature resistant biaxial strain gauges are used, attached axially and circumferentially to the sidewalls and radially and circumferentially to the base plate. A corresponding wall thermocouple is placed next to each strain gauge to ensure the accuracy of synchronous strain and temperature acquisition.

[0044] Step 3: Based on the wall temperature collected synchronously at each strain-temperature combination test point, retrieve the elastic modulus and Poisson's ratio of the heat storage tank material at the corresponding temperature, and combine them with the strain data collected at each strain-temperature combination test point. Calculate the axial stress, circumferential stress, or radial stress corresponding to each strain-temperature combination test point according to Hooke's Law to obtain the thermo-mechanical coupling stress value of each strain-temperature combination test point under the dynamic temperature field.

[0045] Based on the temperature at the strain-temperature combination test point Call the elastic modulus of the storage tank material at the corresponding temperature. Poisson's ratio Based on the strain values ​​ε1 and ε2 measured by the biaxial strain gauge in two directions, Hooke's law is used to calculate the principal stresses in the two directions respectively. , :

[0046] ;

[0047] ;

[0048] For the sidewall of the thermal storage tank, subscript 1 represents the axial direction and subscript 2 represents the circumferential direction; for the bottom plate of the thermal storage tank, subscript 1 represents the radial direction and subscript 2 represents the circumferential direction.

[0049] Subsequently, stress-time curves and stress-liquid level curves were established for each strain-temperature combination test point to obtain the stress variation law of each strain-temperature combination test point within a complete operating cycle.

[0050] Step 4: Based on the stress-time variation curves at each strain-temperature combination test point, obtain the maximum stress value, minimum stress value, and stress variation amplitude Δσ at each strain-temperature combination test point within a complete operating cycle. Evaluate the structural strength of the thermal storage tank based on the maximum stress value, and assess the fatigue damage characteristics of the thermal storage tank based on the stress variation amplitude. The maximum stress value and stress variation amplitude mentioned above are calculated using dynamic thermo-mechanical coupling stress.

[0051] Step 5: Compare the maximum stress values ​​at each strain-temperature combination test point to determine the strain-temperature combination test point where the maximum stress is located, and define its location as the strength danger zone; compare the stress change amplitude Δσ at each strain-temperature combination test point to determine the strain-temperature combination test point where the maximum stress change amplitude is located, and define its location as the fatigue danger zone.

[0052] Step 6: Based on the assessment results of the combined strength hazard area and fatigue hazard area, determine the overall hazard area of ​​the thermal storage tank. When the strength hazard area and the fatigue hazard area are located in the same location, that location is determined as the critical hazard area of ​​the thermal storage tank; when the strength hazard area and the fatigue hazard area are located in different locations, the strength control hazard area and the fatigue control hazard area of ​​the thermal storage tank are determined separately.

[0053] Step 7: Statistically analyze the positional changes of the intensity hazard zone and fatigue hazard zone within a complete operating cycle to obtain the dynamic change pattern of the hazard zone as the liquid level and temperature interface change. When the position of the intensity hazard zone or fatigue hazard zone changes, it is determined that the hazard zone has changed. Based on the position of the temperature interface on the heat storage tank wall corresponding to the moment the hazard zone changes, analyze the correspondence between the hazard zone and the change of the temperature interface to obtain the dynamic change characteristics of the hazard zone as the liquid level and temperature interface change.

[0054] Step 8: Based on the maximum stress value, stress change amplitude and occurrence time of the corresponding dangerous area, determine the main dangerous parts of the thermal storage tank in the heat storage and heat release stages, and provide a basis for the structural optimization design and fatigue life analysis of the thermal storage tank.

[0055] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for stress testing and hazardous area assessment of an intermittent heat source storage tank in a fusion device, characterized in that, Includes the following steps: Step 1: The molten salt is transported to the thermal storage tank to reach the minimum liquid level of the thermal storage tank. After the temperature stabilizes, the insulation and ventilation are adjusted to maintain the heat loss rate within the design operating range, thereby constructing the initial wall temperature and heat loss rate consistent with the actual operation of the fusion reactor, so that the thermal storage tank wall forms a temperature interface that changes with the liquid level. Step 2: Turn off the heater of the thermal storage tank, fill the thermal storage tank with molten salt according to the target flow rate to the highest liquid level of the storage tank to complete the thermal storage, and then discharge the molten salt to the lowest liquid level to complete the heat release; set up a test group including strain-temperature combined test points to simultaneously collect strain data, temperature data and liquid level data; Step 3: Calculate the stress value by combining the temperature data of each strain-temperature combination test point, and establish a curve of thermo-mechanical coupling stress changing with time and liquid level; Step 4: Obtain the maximum stress value, minimum stress value, and stress change amplitude based on the curve, and evaluate the structural strength and fatigue damage characteristics of the thermal storage tank respectively. Step 5: Compare the maximum stress value and stress change amplitude of each test group to determine the strength danger zone and fatigue danger zone; Step 6: Based on the assessment results of the combined strength hazard area and fatigue hazard area, determine the critical hazard area or fatigue control hazard area of ​​the thermal storage tank; Step 7: Statistically analyze the location changes of the intensity hazard zone and fatigue hazard zone during the complete operating cycle, and obtain the dynamic change characteristics of the hazard zone with the liquid level and temperature interface. Step 8: Determine the main dangerous areas based on the maximum stress value, stress change amplitude, and occurrence time of the dangerous area.

2. The method for stress testing and hazardous area assessment of an intermittent heat source storage tank in a fusion device according to claim 1, characterized in that, In step 1, the heat loss rate of the side wall and bottom plate of the thermal storage tank is measured by the first heat flow meter and the second heat flow meter, respectively. By adjusting the thickness of the insulation layer and the forced ventilation rate at the bottom of the thermal storage tank, the heat loss rate of the side wall and bottom plate of the thermal storage tank is kept within the design operating range of the thermal storage tank.

3. The method for stress testing and hazardous area assessment of an intermittent heat source storage tank in a fusion device according to claim 1, characterized in that, In step 2, test groups are arranged in a layered layout based on the liquid level change range. At least three test groups are set along the height direction in the liquid level fluctuation coverage area on the side wall of the thermal storage tank, corresponding to the lowest liquid level, the middle liquid level and the highest liquid level. Each test group contains no less than four strain-temperature combination test points evenly arranged along the circumference on the outer surface of the side wall of the thermal storage tank. Each test group covers the temperature interface change area during the liquid level fluctuation process.

4. The method for stress testing and hazardous area assessment of an intermittent heat source storage tank in a fusion device according to claim 3, characterized in that, In step 2, at least four test groups are arranged at the large fillet weld connecting the side wall and the bottom plate of the thermal storage tank, respectively located at the inner fillet weld, the outer fillet weld, the inner side of the side wall adjacent to the fillet weld, and the inner side of the bottom plate of the thermal storage tank adjacent to the fillet weld. Each test group is equipped with no less than four strain-temperature combination test points evenly distributed along the circumference. At least two test groups are arranged on the bottom plate of the thermal storage tank in the central ring and midpoint areas. Each test group is equipped with no less than four strain-temperature combination test points evenly distributed along the circumference on the upper surface of the bottom plate of the thermal storage tank.

5. A method for stress testing and hazardous area assessment of an intermittent heat source storage tank for a fusion device according to claim 3 or 4, characterized in that, Each strain-temperature combined test point includes a biaxial strain gauge and a wall thermocouple. The wall thermocouple and the biaxial strain gauge are installed at the same test position to simultaneously measure the wall strain and wall temperature at the corresponding position. Specifically, the biaxial strain gauges of the strain-temperature combined test points on the side wall of the thermal storage tank are pasted along the axial and circumferential directions, respectively, while the biaxial strain gauges of the strain-temperature combined test points on the bottom plate of the thermal storage tank are pasted along the radial and circumferential directions, respectively. The strain value, wall temperature, and liquid level data of each strain-temperature combined test point are synchronously recorded at one-minute intervals by a data acquisition instrument.

6. The method for stress testing and hazardous area assessment of an intermittent heat source storage tank in a fusion device according to claim 5, characterized in that, In step 3, based on the wall temperature synchronously collected at each strain-temperature combination test point, the elastic modulus and Poisson's ratio of the heat storage tank material at the corresponding temperature are retrieved.

7. The method for stress testing and hazardous area assessment of an intermittent heat source storage tank in a fusion device according to claim 6, characterized in that, Combine the strain data collected synchronously in step 2 to perform thermo-mechanical coupling stress calculation, which is used as the stress value of the strain-temperature combination test point at the corresponding time.

8. The method for stress testing and hazardous area assessment of an intermittent heat source storage tank in a fusion device according to claim 1, characterized in that, In step 6, when the strength hazard area and the fatigue hazard area are located at the same strain-temperature combination test point, that location is identified as the critical hazard area of ​​the thermal storage tank.

9. The method for stress testing and hazardous area assessment of an intermittent heat source storage tank in a fusion device according to claim 8, characterized in that, When the strength hazard zone and the fatigue hazard zone are located at the corresponding positions of different strain-temperature combination test points, the location of the strength hazard zone is defined as the strength control hazard zone and the location of the fatigue hazard zone is defined as the fatigue control hazard zone, respectively.

10. The method for stress testing and hazardous area assessment of an intermittent heat source storage tank in a fusion device according to claim 9, characterized in that, In step 7, when the location of the intensity danger zone or fatigue danger zone changes, it is determined that the danger zone has changed; based on the temperature interface position of the heat storage tank wall corresponding to the time when the danger zone changes, the correspondence between the danger zone and the temperature interface change is analyzed to obtain the dynamic change characteristics of the danger zone as the liquid level and temperature interface change.

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