CN201689068U - Experimental device for thermal conductivity of high-level waste disposing cushion material - Google Patents

Abstract

An experimental device for thermal conductivity of buffer materials for high-level radioactive waste disposal. The walls of the double-layer steel cylinder are filled with insulation materials. A heating cylinder is inserted vertically in the middle of the double-layer steel cylinder, and two heating rods are inserted into the heating cylinder. , There is a probe thermocouple next to the heating rod, the heating cylinder is filled with aluminum powder, and the cavity between the heating cylinder and the double-layer steel cylinder is filled with several layers of bentonite blocks whose thermal conductivity is to be measured. The utility model has the advantages of: (1) the heat conduction device simulates the multi-layer cylindrical conceptual model of the high-level radioactive waste disposal warehouse engineering site; (2) makes the equipment easy to operate and saves manpower; (3) the automatic storage system ensures that the data The stability and accuracy of the results; (4) It can measure the thermal conductivity of various other clays and rocks and soils.

Description

An experimental device for thermal conductivity of buffer materials for high-level radioactive waste disposal

technical field

The utility model relates to an experimental device, in particular to an experimental device for the thermal conductivity of a high-level radioactive waste disposal buffer material.

Background technique

With the development of nuclear science and the application of nuclear technology, the disposal of high-level radioactive waste (referred to as high-level radioactive waste) produced by the nuclear industry has become increasingly urgent. For the harmonious development of the nuclear industry, human beings and nature, many countries plan to adopt a conceptual model of deep geological disposal with multiple barriers to minimize the hazards of high-level radioactive waste. Because bentonite has good thermal stability, nuclide adsorption and extremely low permeability, in this model, many countries choose bentonite as the base material of high-level radioactive waste geological disposal buffer material. , Long half-life, and release a large amount of decay heat at the same time, these heat is the most important factor affecting the stability and safety of the high-level radioactive waste repository, especially the artificial barrier. Decay heat will lead to an increase in the temperature of the repository, which is generally believed to be up to 100°C, which may affect the structure and performance of the buffer material. Therefore, it is necessary to study the thermal conductivity of the buffer material, namely bentonite. Domestic research on the thermal properties of bentonite is mostly limited to the determination of thermal conductivity parameters, while many countries have begun field test research on large-scale high-level radioactive waste disposal. In order to study the change of in-situ thermal properties of bentonite compacted blocks during deep geological disposal of high-level radioactive waste, and to promote the level of domestic high-level radioactive waste disposal in line with international standards, this set of bentonite heat conduction equipment for simulating the engineering site was designed and manufactured.

Contents of the invention

The purpose of this utility model is to provide an experimental device for the thermal conductivity of high-level radioactive waste disposal buffer materials. Simulating the characteristics of the actual engineering site can help expand students' thinking space, stimulate innovation enthusiasm, fully tap the potential of design, and closely integrate scientific research and teaching.

The utility model is realized in this way, which includes double-layer steel cylinder, thermal insulation material, heating cylinder, heating rod, probe thermocouple, bentonite, temperature and humidity sensor, temperature control box, environmental sensor, temperature and humidity signal acquisition conversion module , data display monitoring memory, uninterruptible power supply, characterized in that the wall of the double-layer steel cylinder is filled with thermal insulation materials, a heating cylinder is inserted vertically in the middle of the double-layer steel cylinder, and two heating rods are inserted in the heating cylinder , there is a probe thermocouple next to the heating rod, the heating cylinder is filled with aluminum powder, the cavity between the heating cylinder and the double-layer steel cylinder is filled with several layers of bentonite, and there are several temperature and humidity chambers between the bentonite layer and the bentonite layer. The sensor, heating rod and probe thermocouple are connected to the temperature control box through wires, the temperature and humidity sensor and the environment sensor are respectively connected to the temperature and humidity signal acquisition conversion module, the temperature and humidity signal acquisition conversion module is connected to the data display monitoring memory, and the heating rod is connected to the uninterruptible power supply.

The utility model has the advantages that: (1) the heat conduction device has simulated the multi-layer cylindrical conceptual model of the high-level radioactive waste disposal warehouse engineering site, and has good guidance for studying the change law of temperature and humidity of the buffer material for the high-level radioactive waste disposal on the spot Significance; (2) Both the temperature control and the monitoring and storage system of temperature and humidity data are fully automatic, which makes the equipment easy to operate and saves manpower; (3) The excellent performance parameters of heating rods, sensors, and temperature control instruments and good sealing System and automatic storage system ensure the stability and accuracy of data results; (4) It can measure the thermal conductivity of various other clays and rocks and soils. At the same time, the sensors can be designed arbitrarily according to the requirements, and pressure sensors and moisture sensors can also be embedded in the soil blocks. etc. to study the variation law of expansion force, moisture and other parameters during the temperature change process.

Description of drawings

Fig. 1 is the structural representation of the utility model.

Fig. 2 is a layout diagram of the temperature and humidity sensor of the present invention.

Fig. 3 is another arrangement diagram of the temperature and humidity sensor of the present invention.

In the figure, 1. Double-layer steel cylinder 2. Thermal insulation rock wool 3. Heating cylinder 4. Heating rod 5. Probe thermocouple 6. Aluminum powder 7. Bentonite 8. Temperature and humidity sensor 9. Temperature control box 10. Environmental sensor 11 , Temperature and humidity signal acquisition conversion module 12. Data display monitoring memory 13. Uninterruptible power supply

Detailed ways

As shown in Figure 1, the utility model is realized in such a way that the wall of the double-layer steel cylinder 1 is filled with thermal insulation rock wool 2, and the middle of the double-layer steel cylinder 1 is vertically inserted with a heating cylinder 3, and the inside of the heating cylinder 3 Two heating rods 4 are inserted, and a probe thermocouple 5 is installed next to the heating rod 4. The heating cylinder 3 is filled with aluminum powder 6, and the cavity between the heating cylinder 3 and the double-layer steel cylinder 1 is filled with several layers of bentonite 7. , several temperature and humidity sensors 8 are arranged between the bentonite layer and the bentonite layer, the heating rod 4 and the probe thermocouple 5 are connected to the temperature control box 9 through wires, and the temperature and humidity sensors 8 and the environment sensor 10 are respectively connected to the temperature and humidity signal acquisition conversion module 11 The temperature and humidity signal acquisition conversion module 11 is connected to the data display monitoring memory 12, and the heating rod 4 is connected to the uninterruptible power supply 13.

As a buffer material, bentonite 7 must be compacted into a block with a certain density in order to effectively slow down the migration speed of nuclides, accelerate decay heat conduction, equalize the pressure of surrounding rocks, seal cracks in surrounding rocks and alleviate mechanical damage. The dual function of the barrier and the natural barrier, the decay heat will be relatively slow, in order to simulate this effect, the closed structure of the double-layer steel cylinder 1 filled with thermal insulation rock wool 2 is better, and the gap between the wire and the fastening bolt is used with high temperature resistant glue Sealed to ensure that as little heat and moisture as possible can be lost to the environment outside the device. The heating cylinder 3 simulates the decay heat source of high-level radioactive waste in the center of the multi-layer cylinder, and there are two heating rods 4 inside. Generally, one heating rod is turned on, and the other is spared. Two heating rods 4 can also be activated at the same time to increase the power. Next to the heating rod 4 is the probe thermocouple 5 for temperature measurement. The wires of the heating rod 4 and the probe thermocouple 5 are led out from the center of the top of the double-layer steel cylinder 1 and connected to the temperature control box 9. In order to speed up the heat transfer rate, the heating cylinder 3 is filled with Aluminum powder6. The multiple temperature and humidity sensors 8 embedded in the bentonite block are the main components for measuring temperature and humidity changes. The wires pass through the insulation rock wool 2, are led out from the top of the double-layer steel cylinder 1, and are connected to the temperature and humidity signal acquisition and conversion module 11. .

Arrangement of temperature and humidity sensors

In order to measure the change law of temperature and humidity with time at different positions of the heat source under the action of the simulated decay heat source inside the bentonite 7 compacted block, it is necessary to arrange some miniature temperature and humidity sensors 8 in the soil block. The bentonite blocks are added in a layered manner, from the top to the bottom in order of the 1st to 8th layers. The design position of the temperature and humidity sensor 8 is shown in Fig. 2 and Fig. 3. The numbers on the arrows are the distance from the top of the temperature and humidity sensor probe protective cover to the outer wall of the heating cylinder 3, represented by s. One temperature and humidity sensor is installed at the 0° direction s=70mm on the layer, and one is installed at the 180° direction s=70mm on the fifth layer. Through the temperature and humidity changes of these temperature and humidity sensors at the same position as the heating source, we can understand the simulated high-level radioactive waste Longitudinal temperature and humidity changes of bentonite compacted blocks at the disposal site. Set one at the 90°, 180°, 270° square sound s = 45mm, 20mm, 95mm of the third layer, and set one at the 90°, 0°, 270° direction s = 95mm, 20mm, 45mm of the fifth layer 1, through the temperature and humidity changes of the position sensors in different directions from the heating source on the 3rd and 5th floors, to study and simulate the radial temperature and humidity changes of bentonite compacted blocks at the high-level radioactive waste disposal site. Install an indoor ambient temperature and humidity sensor to understand the impact of ambient temperature and humidity on the heat transfer system.

The installation and arrangement of soil blocks and sensors can also be designed according to the performance characteristics and experimental requirements of different clay and rock soil samples.

Due to the long geological disposal time of high-level radioactive waste and the slow diffusion of water in compacted bentonite, the experimental time of heat conduction test depends on the composition, density and moisture content of bentonite, and generally takes several days to dozens of days. This requires a continuous and stable power supply. The design adopts an uninterruptible power supply (UPS) and a voltage stabilizer to form a power supply system.

The temperature control box mainly monitors the power and temperature of the heating cylinder and the switching between the two heating rods, and at the same time displays the temperature value inside the heating cylinder actually measured by the probe thermocouple. The power and temperature can be set and displayed on the control panel of the temperature control box. The actual output power of the heating rod can be set according to the temperature. % adjustable within the range. The temperature control box is also equipped with an automatic alarm device for heat dissipation and temperature, which increases the safety factor.

The data display monitoring memory is realized by the online monitoring software of bentonite thermal conductivity. The software can automatically display the temperature and humidity value of the temperature and humidity sensor in real time at the corresponding position of the heat conduction system diagram, and can perform simple online data analysis. The temperature and humidity data at different times will be It is automatically stored in the corresponding file, and can be converted into a commonly used file format at any time for detailed data analysis and organization. Parameters and schematic diagrams in the software can be set freely according to needs. For example, the data storage time interval can be adjusted according to the speed of temperature and humidity changes. The initial temperature and humidity changes in the experiment are faster, the interval can be set shorter, and the interval in the later stage of the experiment can be longer.

The power supply adopts 220V AC, and supplies stable and continuous current to the whole set of equipment through UPS and voltage stabilizer. The heating element adopts an industrial dry-fired electric heating tube with a rated power of 1.1kW, a diameter of 10mm, and a length of 400mm, which can be continuously heated for more than 3000 hours. The sensor adopts a protective industrial high-precision temperature and humidity sensor. The temperature and humidity sensor has a protective cover. The pores of the protective cover prevent bentonite powder, dust and macromolecular particles from entering, but the gas can enter, so that the temperature and humidity can be effectively detected. The pressure of the compacted bentonite block protects the sensor chip, thereby prolonging the service life of the sensor. Relative humidity measurement range: 0～100%RH, precision: ±1.8%RH; temperature measurement range: -40～+123.8℃; precision: ±0.3℃; response time: <4s. The outer steel cylinder of the double-layer steel cylinder is 10mm thicker, and the inner steel cylinder of the double-layer steel cylinder needs to be drilled, which is 1mm thinner. level two. The temperature controller is an output power regulator with a current of 40A and a controllable temperature range of ±3°C. Equipment startup and experiment

Put the ready-to-use 90° fan-shaped bentonite compacted block with a certain initial moisture content and compacted density into the heating system. Fill in the gaps, seal the top cover, and connect the various lines of the whole set of equipment. Open the thermal conduction online monitoring system software and set various parameters. Turn on the power, set the temperature and power value on the temperature control box, start the heating, start the experiment, the temperature and humidity data are automatically displayed and stored in the software.

Claims (1)

1. the experimental provision of a high-level radioactive-waste disposal padded coaming thermal conductivity, it comprises double-deck steel cylinder, heat preserving and insulating material, cartridge heater, heating rod, the probe thermopair, bentonitic clay, Temperature Humidity Sensor, temperature control box, environmental sensor, temperature-humidity signal is gathered modular converter, the data presentation monitoring memory, uninterrupted power source, it is characterized in that being filled with heat preserving and insulating material in the barrel of double-deck steel cylinder, the centre of double-deck steel cylinder vertically is inserted with cartridge heater, be inserted with two heating rods in the cartridge heater, the heating rod next door is provided with the probe thermopair, be filled with aluminium powder in the cartridge heater, be filled with the several layers bentonitic clay in the cavity between cartridge heater and the double-deck steel cylinder, be provided with several Temperature Humidity Sensors between bentonite bed and the bentonite bed, heating rod is connected temperature control box with the probe thermopair by lead, Temperature Humidity Sensor is connected temperature-humidity signal respectively with environmental sensor and gathers modular converter, temperature-humidity signal is gathered modular converter linking number monitoring memory according to the show, and heating rod connects uninterrupted power source.

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