阅读说明：本技术 一种超高温熔化工质密度在线测量装置及方法 (Online measuring device and method for density of ultra-high temperature melting working medium ) 是由 顾培文 曹克美 张梦威 于 2020-07-23 设计创作，主要内容包括：本发明公开了一种超高温熔化工质密度在线测量装置及方法,所述装置包括石墨坩埚(6)、保温系统、温度测量及观测系统、密度测量系统、辅助系统和耐高温石英外罩(1)；利用本发明提出的方法和设计的试验装置,能够将熔化工质最高加热到3000K,并且在线测量其密度值。本发明能够有效弥补当前核电厂严重事故分析所存在的熔化工质密度数据不精确的问题,提高严重事故分析的整体准确性,为建立有效的严重事故缓解措施提供支撑和保障作用。(The invention discloses an ultra-high temperature melting working medium density on-line measuring device and a method, wherein the device comprises a graphite crucible (6), a heat preservation system, a temperature measuring and observing system, a density measuring system, an auxiliary system and a high temperature resistant quartz outer cover (1); by utilizing the method and the designed test device, the melting working medium can be heated to 3000K at most, and the density value of the melting working medium can be measured on line. The method can effectively solve the problem that the density data of the molten working medium is inaccurate in the current serious accident analysis of the nuclear power plant, improve the overall accuracy of the serious accident analysis, and provide support and guarantee for establishing effective serious accident relieving measures.)

1. The device for measuring the density of the ultra-high temperature melting working medium on line is characterized by comprising a graphite crucible (6), a heat preservation system, a temperature measuring and observing system, a density measuring system, an auxiliary system and a high temperature resistant quartz outer cover (1);

the heat preservation system is arranged in the high-temperature-resistant quartz outer cover (1), and comprises a heat insulation reflection layer (5) surrounding the graphite crucible (6) and an alternating current coil group (3) which is connected with an alternating power supply (18) and is wound outside the heat insulation reflection layer (5);

the temperature measuring and observing system comprises an infrared thermometer (7) and a camera (8) which are arranged outside the high-temperature-resistant quartz outer cover (1), and a reflective prism (9) which is arranged in the high-temperature-resistant quartz outer cover (1), wherein the reflective prism (9) is arranged above the graphite crucible (6), and the infrared thermometer (7) and the camera (8) measure and observe the molten working medium (4) in the graphite crucible (6) through a hole on the high-temperature-resistant quartz outer cover (1) by using the reflective prism (9);

the auxiliary system comprises a vacuum pump (17) and an argon injection system (13), argon is injected into the high-temperature-resistant quartz outer cover (1) through the argon injection system (13), a pressure gauge (15) is arranged on the high-temperature-resistant quartz outer cover (1), the vacuum pump (17) is used for pumping the high-temperature-resistant quartz outer cover (1), the oxygen partial pressure in the high-temperature-resistant quartz outer cover (1) is reduced, and metal in the melting working medium (4) in the graphite crucible (6) is prevented from being combusted;

density measurement system sets up outside high temperature resistant quartz cover (1), including high temperature resistant capillary (10), lift (12), regulation isolation valve (16) and high-pressure argon gas case (19), lift (12) are adjusted high temperature resistant capillary (10) are in the depth of insertion in graphite crucible (6), high-pressure argon gas case (19) are passed through it is right to adjust isolation valve (16) inject argon gas in high temperature resistant capillary (10), it measures to be provided with manometer (14) on high temperature resistant capillary (10) pressure in high temperature resistant capillary (10).

2. The on-line measuring device for the density of the ultra-high temperature melting working medium according to claim 1, wherein the inner surface of the heat insulation reflecting layer (5) is provided with a reflecting layer film with extremely low absorptivity for reducing the heat dissipation of the graphite crucible.

3. The on-line measuring device for the density of the ultra-high temperature melting working medium according to claim 1, characterized in that an infrared thermometer (11) is installed at an opening on the outer side of the high temperature resistant quartz outer cover (1) and is used for monitoring the temperature of the outer surface of the graphite crucible (6).

4. An on-line measuring method for density of an ultra-high temperature melting working medium, which is characterized by comprising the on-line measuring device for density of the ultra-high temperature melting working medium as set forth in any one of claims 1 to 3, and the method comprises the following steps:

preparation of a test working medium: determining the mass and components of oxides, metals or other substances in the melting working medium (4), grinding the substances into powder, compacting the powder into blocks by using a press, wherein the external diameter of each block is slightly smaller than the internal diameter of the graphite crucible (6), and the height of each block is lower than the depth of the graphite crucible (6);

atmosphere control: the melting working medium (4) is placed into the graphite crucible (6), and the device is sealed; opening the vacuum pump (17) for pumping, and then opening the argon injection system (13) to fill inert gas;

heating process: starting the alternating power supply (18) to raise the temperature of the graphite crucible (6);

and (3) smelting: the graphite crucible (6) melts the melting working medium (4), and the melting process of the melting working medium (4) is observed and the temperature of the top of the melting working medium (4) is measured by utilizing the triangular reflector (9), the infrared thermometer (7) and the camera (8) above the graphite crucible (6); if the top of the melting working medium (4) forms a liquid state and reaches the specified measurement temperature, the power of the alternating power supply (18) can be properly adjusted to maintain the state of the melting working medium (4);

density measurement: a, inserting the high-temperature resistant capillary tube (10) into the melting working medium (4) by using the lifting system (12) at a certain depth, and opening the adjusting isolation valve (16) to control the argon injection flow of the high-pressure argon box (19); b maintaining the opening of the regulating isolating valve (16) when the pressure gauge (14) indicates that the pressure fluctuation can be clearly displayed; c, recording pressure data of the pressure gauge (14) and the pressure gauge (15); d, changing the insertion depth of the high-temperature resistant capillary (10) in the molten working medium (4) through the lifter (12), and repeating the processes a, b and c;

data processing and analysis: and reading the pressure difference between the pressure gauge (14) and the pressure gauge (15), performing fitting analysis on the moving distance of the lifter (12), and finally obtaining the density value of the melting working medium (4) by combining the geometric parameters of the high-temperature resistant capillary (10).

5. The method for measuring the density of the ultrahigh-temperature molten working medium according to claim 4, wherein the atmosphere control step can be performed for a plurality of times.

6. The on-line measuring method for the density of the ultra-high temperature melting working medium according to claim 4, characterized in that the temperature of the graphite crucible (6) and the melting working medium (4) is changed by adjusting the power of the alternating power supply (18), the density measuring step and the data processing and analyzing step are repeated to obtain the density of the melting working medium (4) under different temperature conditions, and finally the density library of the melting working medium (4) is formed.

Technical Field

The invention belongs to the technical field of serious accident mitigation measures of pressurized water reactor nuclear power plants, and particularly relates to the fields of analysis of a reactor core melting process, design of in-reactor melting working medium retention measures and research of out-of-reactor melting working medium mitigation strategies.

Background

The mitigation of serious accidents in nuclear power plants is one of the key matters that must be considered in the nuclear power research and design stage. Due to the presence of core decay heat, the fuel (uranium dioxide), cladding material (zirconium metal), internals (stainless steel), and pressure vessel wall (carbon steel) within the core may all melt in the event of an accident, creating an in-core melting process that poses a challenge to the integrity of the pressure vessel. If the pressure vessel fails in an accident, the molten working medium in the reactor can enter the containment vessel to melt the concrete bottom plate, which may cause the serious consequence of the release of radioactive substances to the outside.

The main tasks of the serious accident analysis are to research the accident process, develop reasonable and feasible serious accident mitigation measures and provide guarantee for the safety of nuclear power. Due to the complexity of the serious accident of the nuclear power plant, the serious accident process is difficult to simulate by adopting a test method, and the effectiveness of a serious accident mitigation strategy is difficult to verify by adopting real materials, so that the development of numerical simulation calculation is the most important means for analyzing the current serious accident.

The numerical simulation analysis of the serious accident depends on a basic database of the physical properties of the molten working medium after the reactor core is molten. The melting working medium mainly comprises uranium dioxide and zirconium dioxide, the melting point is above 2500 ℃, and the basic data of the physical properties of the melting working medium under the high-temperature condition are difficult to obtain. The physical property database at the solid state normal temperature has certain influence on the accuracy and the effectiveness of a calculation result, and a large design conservative margin is usually required to cover the analysis uncertainty caused by the deviation of the physical property database.

According to the existing serious accident analysis, the density of the molten working medium under ultrahigh temperature is an important parameter for influencing the serious accident phenomenon and analyzing and evaluating the serious accident relieving measures. If the density value of the melting working medium adopted by calculation and analysis has certain deviation with the real density value under the ultra-high temperature condition, completely different analysis results can be caused, and even the conclusion that the serious accident mitigation strategy is invalid can be obtained.

Aiming at the composition characteristics of the melting working medium of the nuclear power plant, the invention develops a test method which can melt the melting working medium, keep the liquefaction state of the melting working medium and measure the density of the melting working medium on line. Compared with the original density prediction method, the method obtains the density of the molten working medium under the ultrahigh temperature condition without carrying out calculation extrapolation, so that the result is more accurate, and the conclusion of serious accident analysis is more reliable.

Disclosure of Invention

The invention aims to provide an ultrahigh-temperature molten working medium density on-line measuring device, which is a test method for keeping the ultrahigh-temperature molten working medium density on a liquefied state and carrying out on-line density measurement. The device comprises a graphite crucible (6), a heat preservation system, a temperature measurement and observation system, a density measurement system, an auxiliary system and a high-temperature-resistant quartz outer cover (1);

the heat preservation system is arranged in the high-temperature-resistant quartz outer cover (1), and comprises a heat insulation reflection layer (5) surrounding the graphite crucible (6) and an alternating current coil group (3) which is connected with an alternating power supply (18) and is wound outside the heat insulation reflection layer (5);

the temperature measuring and observing system comprises an infrared thermometer (7) and a camera (8) which are arranged outside the high-temperature-resistant quartz outer cover (1), and a reflective prism (9) which is arranged in the high-temperature-resistant quartz outer cover (1), wherein the reflective prism (9) is arranged above the graphite crucible (6), and the infrared thermometer (7) and the camera (8) measure and observe the molten working medium (4) in the graphite crucible (6) through a hole on the high-temperature-resistant quartz outer cover (1) by using the reflective prism (9);

the auxiliary system comprises a vacuum pump (17) and an argon injection system (13), argon is injected into the high-temperature-resistant quartz outer cover (1) through the argon injection system (13), a pressure gauge (15) is arranged on the high-temperature-resistant quartz outer cover (1), the vacuum pump (17) is used for pumping the high-temperature-resistant quartz outer cover (1), the oxygen partial pressure in the high-temperature-resistant quartz outer cover (1) is reduced, and metal in the melting working medium (4) in the graphite crucible (6) is prevented from being combusted;

density measurement system sets up outside high temperature resistant quartz cover (1), including high temperature resistant capillary (10), lift (12), regulation isolation valve (16) and high-pressure argon gas case (19), lift (12) are adjusted high temperature resistant capillary (10) are in the depth of insertion in graphite crucible (6), high-pressure argon gas case (19) are passed through it is right to adjust isolation valve (16) inject argon gas in high temperature resistant capillary (10), it measures to be provided with manometer (14) on high temperature resistant capillary (10) pressure in high temperature resistant capillary (10).

Preferably, the inner surface of the heat insulation reflecting layer (5) is provided with a reflecting layer film with extremely low absorptivity, and the heat dissipation of the graphite crucible is reduced.

Preferably, an infrared thermometer (11) is installed at an opening on the outer side of the high-temperature-resistant quartz outer cover (1) and used for monitoring the temperature of the outer surface of the graphite crucible (6).

The invention also provides an on-line measuring method for the density of the ultra-high temperature melting working medium, which comprises the following steps:

preparation of a test working medium: determining the mass and components of oxides, metals or other substances in the melting working medium (4), grinding the substances into powder, compacting the powder into blocks by using a press, wherein the external diameter of each block is slightly smaller than the internal diameter of the graphite crucible (6), and the height of each block is lower than the depth of the graphite crucible (6);

atmosphere control: the melting working medium (4) is placed into the graphite crucible (6), and the device is sealed; opening the vacuum pump (17) for pumping, and then opening the argon injection system (13) to fill inert gas;

heating process: starting the alternating power supply (18) to raise the temperature of the graphite crucible (6);

and (3) smelting: the graphite crucible (6) melts the melting working medium (4), and the melting process of the melting working medium (4) is observed and the temperature of the top of the melting working medium (4) is measured by utilizing the triangular reflector (9), the infrared thermometer (7) and the camera (8) above the graphite crucible (6); if the top of the melting working medium (4) forms a liquid state and reaches the specified measurement temperature, the power of the alternating power supply (18) can be properly adjusted to maintain the state of the melting working medium (4);

density measurement: a, inserting the high-temperature resistant capillary tube (10) into the melting working medium (4) by using the lifting system (12) at a certain depth, and opening the adjusting isolation valve (16) to control the argon injection flow of the high-pressure argon box (19); b maintaining the opening of the regulating isolating valve (16) when the pressure gauge (14) indicates that the pressure fluctuation can be clearly displayed; c, recording pressure data of the pressure gauge (14) and the pressure gauge (15); d, changing the insertion depth of the high-temperature resistant capillary (10) in the molten working medium (4) through the lifter (12), and repeating the processes a, b and c;

data processing and analysis: and reading the pressure difference between the pressure gauge (14) and the pressure gauge (15), performing fitting analysis on the moving distance of the lifter (12), and finally obtaining the density value of the melting working medium (4) by combining the geometric parameters of the high-temperature resistant capillary (10).

Preferably, the atmosphere control step may be performed a plurality of times.

Preferably, the temperature of the graphite crucible (6) and the temperature of the melting working medium (4) are changed by adjusting the power of the alternating power supply (18), the density measuring step and the data processing and analyzing step are repeated, the density of the melting working medium (4) under different temperature conditions is obtained, and finally the density library of the melting working medium (4) is formed.

The invention provides a test method for melting a melting working medium of a nuclear power plant and measuring the density of the melting working medium under an ultrahigh temperature condition, and a corresponding test device is designed. By utilizing the method and the designed test device, the melting working medium can be heated to 3000K at most, and the density value of the melting working medium can be measured on line. The method can effectively solve the problem that the density data of the molten working medium is inaccurate in the current serious accident analysis of the nuclear power plant, improve the overall accuracy of the serious accident analysis, and provide support and guarantee for establishing effective serious accident relieving measures.

Drawings

FIG. 1 is a simulation diagram of a transient reaction process test of a lower head melting working medium;

FIG. 2 is a plan view of a melting and density measurement scheme for a molten working medium;

wherein: 1-high temperature resistant quartz outer cover; 2, a support frame; 3-alternating current coil; 4-melting the working medium; 5-heat insulation reflecting layer; 6-graphite crucible; 7-infrared thermometer; 8-a camera; 9-a three-edged reflector; 10-high temperature resistant capillary; 11-infrared thermometer; 12-a lift; 13-argon injection system; 14-pressure gauge; 15-pressure gauge; 16-adjusting the isolation valve; 17-a vacuum pump; 18-an alternating power supply; 19-high pressure argon tank.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

The main body of the test device designed by the invention comprises a graphite crucible, a heating and heat-preserving system, a temperature measuring and observing system, a density measuring system and an auxiliary system. The method utilizes the strong magnetic induction characteristic of graphite to absorb electromagnetic energy generated by a power supply so as to realize non-contact heating of a melting working medium; the high thermal conductivity of the graphite is utilized to realize the accurate measurement of the temperature of the melting working medium; the high melting point of graphite is utilized to ensure the purity of the molten working medium in the test process; the prism above the melting working medium is utilized to simultaneously realize the temperature measurement of the top surface of the melting pool and the video recording of the melting process; the method comprises the steps of utilizing a capillary tube capable of moving up and down, an adjusting isolation valve and a related pressure gauge to generate bubbles, penetrating through the capillary tube, and measuring the density of a molten working medium on line by measuring the pressure difference between the inside and the outside of the capillary tube and the moving distance of the capillary tube. Specifically, according to the test method and the concept of the invention, a recommended test device is formed, and comprises a graphite crucible, an alternating current coil and power supply, an infrared thermometer, a camera, a high-temperature-resistant quartz outer cover, an adiabatic reflecting layer, a reflective triple prism, a high-temperature-resistant capillary tube, an adjusting isolation valve, a lifting system and the like. By adopting the test method and the recommended test device provided by the invention, the density of the molten working medium under the ultrahigh temperature condition can be measured on line.

As shown in fig. 1, the present invention adopts the following technical solutions:

1) the test device comprises a graphite crucible, a heating system, a heat preservation system, a temperature measurement and observation system, a density measurement system, an auxiliary system and the like. The overall structure of the device is shown in fig. 1 and 2;

2) the graphite crucible is made of compact graphite material, and the melting working medium to be melted is placed in the graphite crucible. The graphite has good magnetic induction and high thermal conductivity, and can absorb most of electromagnetic energy emitted by alternating current, so that the temperature of the graphite crucible is increased and is quickly conducted to the melting working medium, and the temperature of the melting working medium is increased;

3) the heat preservation system mainly comprises an alternating power supply, a coil group wound around the graphite crucible and an adiabatic reflection layer. The alternating power supply generates alternating current with a certain frequency, the alternating current passes through the coil group around the crucible, and a magnetic field with a certain frequency is formed around the coil group. Because the inert gas around the coil and the heat insulation reflecting layer hardly absorb the energy of the magnetic field, the energy is mainly absorbed by the graphite crucible, and the annular induced current is generated in the graphite crucible for heating the crucible. The heat insulation reflecting layer is arranged around the graphite crucible, and the holes are formed in part due to the requirements of infrared temperature measurement and density measurement. The heat-insulating reflecting layer has low heat conductivity, and the inner surface of the heat-insulating reflecting layer is provided with a reflecting layer film with low absorptivity, so that the heat dissipation of the graphite crucible is reduced;

4) the temperature measuring and observing system mainly comprises a plurality of infrared thermometers, a camera and a reflecting prism. The infrared thermometer and the camera arranged above can simultaneously measure and observe the temperature of the upper surface of the melting working medium and the melting process of the melting working medium by utilizing the reflection effect of the triangular prism.

5) The density measuring system mainly comprises a high-temperature resistant capillary tube, a lifter, an adjusting isolation valve and a plurality of pressure gauges. Argon is injected into the capillary at different insertion depths, and the pressure difference between the inside and the outside of the capillary is measured to obtain the density of the molten working medium.

6) The auxiliary system mainly comprises a vacuum pump and an inert gas tank. The oxygen partial pressure in the device is reduced by a series of operations such as air extraction, inert gas tank exhaust and the like of the gas in the test device, and the metal in the melting working medium is prevented from burning.

The specific test method of the device of the invention is as follows:

1) preparation of a test working medium: determining the quality and components of oxides, metals or other substances in the molten working medium according to test requirements, grinding the substances into powder, compacting the powder into blocks (4) by using a press, wherein the outer diameter of each block is slightly smaller than the inner diameter of a graphite crucible, and the height of each block is lower than the depth of the crucible;

2) atmosphere control: the blocky test working medium is put into the graphite crucible (6), and the test device finishes covering and sealing. The vacuum pump (17) is used for pumping, and an argon injection system (13) is used for filling inert gas. After multiple charging and discharging, the oxygen partial pressure in the test device is reduced, the inert gas partial pressure is improved, an inert environment is formed, and the metal is prevented from burning in the test process.

3) Heating process: the alternating power supply (18) is started and the power supply power is slowly boosted. The magnetism sensitivity of the heat insulation reflecting layer (5) is poor, and electromagnetic energy generated by an alternating power supply is mainly absorbed by the graphite crucible (6), so that the temperature of the graphite crucible is gradually increased. An infrared thermometer (11) is arranged on the lateral side of the graphite crucible and is used for monitoring the temperature of the outer surface of the graphite crucible. According to the temperature indication, the power of the power supply can be adjusted, and the graphite crucible is prevented from being melted due to too fast temperature rise.

4) And (3) smelting: the graphite crucible (6) transfers the heat of the graphite crucible to the melting working medium (4) in a heat conduction mode, so that the melting working medium is melted. The melting process of the melting working medium can be observed and the temperature at the top of the melting working medium can be measured by utilizing the prism (9), the infrared thermometer (7) and the camera (8) above the graphite crucible. If the top of the melting working medium forms a liquid state and reaches the specified measurement temperature, the power supply power can be properly adjusted to maintain the current state of the melting working medium.

5) Density measurement: a high-temperature resistant capillary tube (10) is inserted into a certain depth of a melting working medium by using a lifting system (12), an adjusting isolation valve (16) is opened, the injection flow of argon is controlled, and the pressure (14) in the capillary tube and the pressure (15) in a quartz outer cover are observed. When the pressure (14) in the capillary (10) indicates that the pressure fluctuation can be clearly displayed, the opening degree of the regulating isolation valve (16) is maintained, and the pressure data of the pressure gauges (14) and (15) are recorded. The insertion depth of the capillary in the melting working medium is changed through the lifting system, and the previous processes of argon injection, pressure observation and data recording are repeated.

6) Data processing and analysis: and the density value of the melting working medium at high temperature is finally obtained by performing fitting analysis on the pressure difference between the pressure gauges (14) and (15) and the moving distance of the lifting system and combining the geometric parameters of the capillary.

7) Establishing density libraries under different temperature conditions: the temperatures of the graphite crucible and the melting working medium are changed by adjusting the power of the alternating power supply, and the previous steps 5 and 6 are repeated, so that the density of the melting working medium under different temperature conditions can be obtained, and a melting working medium density library is finally formed, thereby providing basic data for the serious accident analysis of the nuclear power plant.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations. The foregoing examples or embodiments are merely illustrative of the present invention, which may be embodied in other specific forms or in other specific forms without departing from the spirit or essential characteristics thereof. The described embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. The scope of the invention should be indicated by the appended claims, and any changes that are equivalent to the intent and scope of the claims should be construed to be included therein.