Device and method for measuring internal pressure of radioactive container under fire working condition

Abstract

The invention relates to a device and method for measuring the internal pressure of a radioactive container under a fire working condition, the container comprises an inner container and an outer container, the inner container is arranged in the outer container, and the measuring device comprises a pressure guide pipe, a first pressure measuring element, a second pressure measuring element and a controller; one end of the pressure guide pipe can extend into the inner container of the container, the other end can extend out of the container and is communicated with the first pressure measuring element, and a heat insulation structure is arranged on at least the part of the pressure guide pipe outside the container; the first pressure measuring element is used for measuring the pressure in the inner container; the second pressure measuring element is used for measuring environment pressure; the controller is connected to the first pressure measuring element and the second pressure measuring element so as to obtain the gauge pressure in the inner container according to the measured values of the first pressure measuring element and the second pressure measuring element. The heat insulation structure is arranged on the pressure guide pipe, so that the measurement value of the first pressure measuring element is closer to the pressure value in the inner container, the measurement error is reduced, and the second pressure measuring element is arranged, so that the pressure measurement is more accurate through standard pressure source correction.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure measuring equipment, and in particular to a device and method for measuring the internal pressure of a radioactive container under fire conditions. Background Art

[0002] According to relevant national regulations, some radioactive material transport containers need to verify their safety performance under fire conditions before they are put into use. When conducting tests under fire conditions, the thermal environment temperature of the transport container can reach 800°C. The high temperature makes it difficult to measure the internal pressure of the transport container. This is mainly because when the pressure is measured directly by a pressure gauge, the pressure gauge is generally not resistant to high temperatures, and the data line of the pressure sensor is also not resistant to high temperatures. Therefore, it cannot be used in fire conditions. In addition, the high temperature environment of the fire will increase the temperature in the pressure taking pipe. When measuring the pressure in the container, there is a difference between the temperature in the container and the temperature in the pressure taking pipe, so there is a deviation between the measured value of the pressure gauge and the pressure value in the container. The above problems need to be solved urgently. Summary of the invention

[0003] The invention discloses a device and a method for measuring the internal pressure of a radioactive container under fire conditions, aiming to solve the technical problems existing in the prior art.

[0004] The present invention adopts the following technical solutions:

[0005] In a first aspect, the present invention provides a device for measuring the internal pressure of a radioactive container under fire conditions, wherein the container comprises an inner container and an outer container, wherein the inner container is arranged in the outer container, and the measuring device comprises a pressure pipe, a first pressure measuring element, a second pressure measuring element and a controller; one end of the pressure pipe can extend into the inner container of the container, and the other end can extend out of the container, and is connected to the first pressure measuring element, and at least the portion of the pressure pipe located outside the container is provided with a heat insulation structure; the first pressure measuring element is used to measure the pressure in the inner container; the second pressure measuring element is used to measure the ambient pressure; the controller is connected to the first pressure measuring element and the second pressure measuring element to obtain the gauge pressure in the inner container based on the measurement values ​​of the first pressure measuring element and the second pressure measuring element.

[0006] In the device for measuring the internal pressure of a radioactive container under fire conditions of the present invention, the thermal insulation structure is an aerogel layer arranged on the surface of the pressure conducting pipe.

[0007] In the device for measuring the internal pressure of a radioactive container under fire conditions of the present invention, the pressure-conducting tube is made of stainless steel, has a diameter of 3 mm and a thickness of 0.5 mm.

[0008] In the device for measuring the internal pressure of a radioactive container under fire conditions of the present invention, the measuring range of the first pressure measuring element is 0 to 100 kPa; the measuring range of the second pressure measuring element is 0 to 10 kPa.

[0009] In the device for measuring the internal pressure of a radioactive container under fire conditions of the present invention, the pressure-conducting tube is sealed and connected to at least the inner container through a sealing connector; the sealing connector includes a sealing member and a connector; the sealing member is sleeved and sealingly connected to the pressure-conducting tube, and the sealing member abuts and seals against the edge of the opening of the inner container; the connector includes a fixing member and a threaded member; the fixing member is used to be fixedly connected to the surface of the outer container, and has a channel connected to the outer container; the threaded member is sleeved on the outside of the fixing member and is threadedly connected to the fixing member; the pressure-conducting tube is passed through the threaded member, so that when the threaded member is threadedly connected to the fixing member, the sealing member abuts and seals against the edge of the opening of the inner container.

[0010] In the device for measuring the internal pressure of a radioactive container under fire conditions of the present invention, the sealing member is a truncated cone structure, which is coaxially arranged with the pressure guiding pipe, and the side surface of the truncated cone structure abuts against the edge of the opening of the inner container for sealing.

[0011] In the device for measuring the internal pressure of a radioactive container under fire conditions of the present invention, the seal, the pressure pipe and the container are all made of metal, and the thermal expansion coefficient of the seal is greater than the thermal expansion coefficients of the pressure pipe and the container.

[0012] In a second aspect, the present invention further provides a measurement method using the above-mentioned measurement device, which comprises the following steps:

[0013] A preliminary sealing test is performed by filling the pressure pipe with gas until the measured pressure is reached and then stopping the gas supply. The controller records the measured value of the first pressure measuring element and calculates the decreasing rate of the measured value.

[0014] If the measured value decreasing rate is greater than or equal to the first threshold, then check each connection until the measured value decreasing rate is less than the first threshold,

[0015] If the measured value decreasing rate is less than the first threshold, proceed to the next step;

[0016] The sealing performance is tested again by connecting the pressure pipe to the container and measuring the sealing performance of the measuring device again.

[0017] If the sealing meets the requirements, the container is transferred to a fire simulation environment to check whether the first pressure measuring element and the second pressure measuring element are normal.

[0018] If normal, proceed to the next step.

[0019] If it is abnormal, then debug the first pressure measuring element and the second pressure measuring element until they are displayed as normal;

[0020] If the sealing does not meet the requirements, repeat this step;

[0021] The test is started, the fire simulation environment is adjusted to a fire condition, and the measurement values ​​of the first pressure measuring element and the second pressure measuring element are stored and recorded through a controller.

[0022] In the measuring method of the present invention, before the preliminary sealing test, the following steps are also included:

[0023] According to the model of the container, determine the model of the pressure pipe and the range and accuracy of the first pressure measuring element and the second pressure measuring element;

[0024] A pressure pipe connection is used to connect the pressure pipe to the first pressure measuring element;

[0025] Initial installation: connect the first load cell and the second load cell to the controller, turn on the controller to test whether the controller, the first load cell and the second load cell are working properly.

[0026] If yes, proceed to the next step.

[0027] If no, repeat this step.

[0028] The measuring method of the present invention further includes a device calibration step;

[0029] The device calibration step comprises:

[0030] Connect one side of the pressure-conducting pipe connected to the container to a standard pressure source;

[0031] Obtaining a correction coefficient according to the pressure value of the standard pressure source and the measurement value of the first pressure measuring element;

[0032] The controller records the model of the pressure guiding tube and the correction coefficient in a one-to-one correspondence.

[0033] The technical solution adopted by the present invention can achieve the following beneficial effects:

[0034] The present invention mainly provides a device for measuring the internal pressure of a radioactive container under fire conditions. The device connects the inner container with a first pressure measuring element by a pressure conducting pipe, thereby realizing pressure externalization, and the first pressure measuring element is far away from the fire environment, so that the first pressure measuring element can work normally. In addition, a heat insulation structure is arranged on the pressure conducting pipe, so that the influence of the high temperature of the fire environment on the gas temperature in the pressure conducting pipe is reduced, so that the measurement value of the first pressure measuring element is closer to the pressure value in the inner container, and the measurement error is reduced. By arranging a second pressure measuring element, the difference between the measurement values ​​of the first pressure measuring element and the second pressure measuring element is used as the gauge pressure in the inner container, so that the pressure measurement is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments, which constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions explain the present invention and do not constitute improper limitations on the present invention. In the drawings:

[0036] Figure 1 This is one of the structural schematic diagrams of a device for measuring the internal pressure of a radioactive container under fire conditions according to the present invention;

[0037] Figure 2 This is a second structural schematic diagram of a device for measuring the internal pressure of a radioactive container under fire conditions according to the present invention;

[0038] Figure 3 It is a structural schematic diagram of the connecting piece of the present invention;

[0039] Figure 4 It is a schematic structural diagram of the pressure guiding tube of the present invention.

[0040] Description of reference numerals:

[0041] 1. Pressure pipe; 11. Inner tube; 111. Meltable structure; 12. Outer tube; 2. First pressure measuring element; 3. Second pressure measuring element; 4. Controller; 5. Insulation structure; 6. Sealing connector; 61. Sealing element; 62. Connector; 621. Fixing element; 6211. Passage; 622. Screwed connector; A. Container; A1. Inner container; A2. Outer container. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. In the description of the present invention, it should be noted that the term "or" is usually used in the sense of including "and / or", unless the content clearly indicates otherwise.

[0043] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or a magnetic connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three or more, etc., unless otherwise clearly and specifically limited.

[0044] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] In order to solve the problems existing in the prior art, the embodiments of the present application provide a device and a method for measuring the internal pressure of a radioactive container under fire conditions.

[0046] Example 1

[0047] This embodiment provides a device for measuring the internal pressure of a radioactive container under fire conditions. The container A includes an inner container A1 and an outer container A2. The inner container A1 is arranged inside the outer container A2. Figure 1 As shown, the measuring device includes a pressure pipe 1, a first pressure measuring element 2, a second pressure measuring element 3 and a controller 4; one end of the pressure pipe 1 can be extended into the inner container A1 of the container A, and the other end can be extended out of the container A and connected to the first pressure measuring element 2, such as a pressure measuring port; specifically, the length and diameter of the pressure pipe 1 are selected according to needs, such as being selected based on the principle of minimizing the impact on the measurement value of the first pressure measuring element 2; at least the part of the pressure pipe 1 located outside the container A is provided with a heat insulation structure 5; the first pressure measuring element 2 is used to measure the pressure in the inner container A1; the second pressure measuring element 3 is used to measure the ambient pressure; the controller 4 is connected to the first pressure measuring element 2 and the second pressure measuring element 3, and is used to obtain the measurement values ​​of the first pressure measuring element 2 and the second pressure measuring element 3, so as to obtain the gauge pressure in the inner container A1 according to the measurement values ​​of the first pressure measuring element 2 and the second pressure measuring element 3, that is, the difference between the measurement values ​​of the first pressure measuring element 2 and the second pressure measuring element 3.

[0048] The present invention provides a device for measuring the internal pressure of a radioactive container under fire conditions. The device connects an inner container A1 with a first pressure measuring element 2 through a pressure conducting pipe 1, thereby realizing pressure externalization. The first pressure measuring element 2 is away from the fire environment, so that the first pressure measuring element 2 can work normally. In addition, a heat insulation structure 5 is provided on the pressure conducting pipe 1, thereby reducing the influence of the high temperature of the fire environment on the gas temperature in the pressure conducting pipe 1, so that the measurement value of the first pressure measuring element 2 is closer to the pressure value in the inner container A1, thereby reducing the measurement error. By providing a second pressure measuring element 3, the difference between the measurement values ​​of the first pressure measuring element 2 and the second pressure measuring element 3 is used as the gauge pressure in the inner container A1, thereby making the pressure measurement more accurate.

[0049] In some preferred embodiments, the thermal insulation structure 5 is an aerogel layer disposed on the surface of the pressure conducting pipe 1; preferably, the thickness of the aerogel layer is 2 mm.

[0050] In some preferred embodiments, the pressure-conducting tube 1 is made of stainless steel, with a diameter of 3 mm (outer diameter) and a thickness of 0.5 mm; thereby, the influence of the pressure-conducting tube 1 on the measurement value of the first pressure measuring element 2 is reduced.

[0051] In some preferred embodiments, the first pressure measuring element 2 and the second pressure measuring element 3 are both pressure gauges.

[0052] In some preferred embodiments, the measuring range of the first pressure measuring element 2 is 0 to 100 kPa (gauge pressure); the measuring range of the second pressure measuring element 3 is 0 to 10 kPa (gauge pressure).

[0053] Preferably, the accuracy of the first pressure measuring element 2 is 1%; the accuracy of the second pressure measuring element 3 is 1%.

[0054] In some preferred embodiments, it also includes a gas charging and discharging interface communicated with the pressure conducting tube 1 , which is used to perform a pressure test on the pressure conducting tube 1 and the connection between the pressure conducting tube 1 and the first pressure measuring element 2 .

[0055] In some preferred embodiments, the controller 4 provides power energy for the first pressure measuring element 2 and the second pressure measuring element 3 on the one hand, and records and stores the measured values ​​of the first pressure measuring element 2 and the second pressure measuring element 3 on the other hand, displays the real-time pressure and maximum pressure of the container A1 through a built-in processing program, and gives a pressure curve; specifically, the acquisition frequency of the controller 4 is greater than or equal to 1 Hz, preferably 10 Hz.

[0056] In some preferred embodiments, Figure 2 and 3As shown, the pressure-guiding pipe 1 is sealed and connected to at least the inner container A1 through a sealing connector 6; the sealing connector 6 includes a sealing member 61 and a connector 62; the sealing member 61 is sleeved and sealed and connected to the outer side of the pressure-guiding pipe 1, and the sealing member 61 is abutted and sealed against the edge of the opening of the inner container A1, such as a metal seal or a high-temperature resistant sealing structure such as a polytetrafluoroethylene sealing gasket; the connector 62 includes a fixing member 621 and a screw member 622; the fixing member 621 is used to be fixedly connected to the surface of the outer container A2, and has a channel 622 connected to the inner side of the outer container A2. 211; the screw connection 622 is sleeved on the outside of the fixing member 621 and is screwed to the fixing member 621; the pressure-conducting tube 1 is installed on the screw connection 622, so that when the screw connection 622 is screwed to the fixing member 621, the sealing member 61 abuts against the edge of the opening of the inner container A1 for sealing; the pressure-conducting tube 1 and the container A are detachably connected through the sealing connector 6, so as to facilitate the replacement of pressure-conducting tubes 1 of different specifications; preferably, the screw connection 622 is screwed to the pressure-conducting tube 1, so as to adjust the abutting force between the sealing member 61 and the edge of the opening of the inner container A1 to a greater extent.

[0057] In some preferred embodiments, Figure 2 As shown, the seal 61 is a frustoconical structure, which is coaxially arranged with the pressure guiding tube 1, and the side of the frustoconical structure abuts and seals against the edge of the opening of the inner container A1; based on the frustoconical structure of the seal 61, the side of the frustoconical structure can abut and seal against the mounting hole on the inner container A1, and can adapt to mounting holes of different specifications.

[0058] In some preferred embodiments, the seal 61, the pressure tube 1 and the container A are all made of metal, and the thermal expansion coefficient of the seal 61 is greater than the thermal expansion coefficients of the pressure tube 1 and the container A. At this time, the sealing performance can be improved by providing a Teflon coating on the surface of the seal 61. For details, reference can be made to the existing high-temperature sealing structure. Based on this, when a fire occurs, the deformation of the seal 61 is greater than that of the pressure tube 1 and the container A, and the abutment between the seal 61 and the mounting hole is tighter, which can improve the sealing performance between the seal 61 and the inner container A1, that is, self-sealing at high temperature is achieved, thereby improving the high-temperature sealing performance. More preferably, the thermal expansion coefficients of the seal 61, the pressure tube 1 and the container A decrease successively. Then, when a fire occurs, the pressure tube 1 also expands, and the abutment force of the pressure tube 1 on the seal 61 increases, thereby also making the abutment between the seal 61 and the mounting hole tighter, thereby improving the high-temperature sealing performance.

[0059] In some preferred embodiments, Figure 4As shown, the pressure-conducting pipe 1 is a double-layer pipe, and there is a vacuum space between the two layers; the double-layer pipe includes an inner pipe 11 and an outer pipe 12, wherein the inner pipe 11 is connected to the first pressure measuring element 2 and is provided with an easily-meltable structure 111, the melting temperature of the easily-meltable structure 111 is lower than the fire temperature (such as a metal with a low melting point), so that when the temperature in the inner pipe 11 is higher than the melting temperature of the easily-meltable structure, it can melt. At this time, due to the connection between the inner and outer pipes, the influence of the expansion of the gas in the inner pipe 11 due to the increase in temperature on the measurement value of the first pressure measuring element 2 can be reduced; specifically, the volume of gas that needs to be discharged to the vacuum space can be calculated according to the highest temperature value in the inner pipe 11 during a fire, and then the volume of the vacuum space can be determined, which can be determined specifically according to the working conditions.

[0060] Example 2

[0061] This embodiment provides a measurement method using the measurement device of the above embodiment 1, which comprises the following steps:

[0062] Preliminary sealing test: gas is filled into the pressure guide pipe 1 until the measured pressure is reached and then the gas supply is stopped. The controller 4 records the measured value of the first pressure measuring element 2 and calculates the decreasing rate of the measured value. The measured pressure is the maximum pressure value in the inner container A1 under the fire condition obtained by simulation calculation.

[0063] If the measured value decrease rate is greater than or equal to the first threshold, then check each connection until the measured value decrease rate is less than the first threshold.

[0064] If the measured value decrease rate is less than the first threshold, then proceed to the next step;

[0065] The sealing performance is tested again. The pressure pipe 1 is connected to the container A, and the sealing performance of the measuring device is measured again. Specifically, the suction gun method or the pressure-testing channel of the controller 4 can be adopted, that is, a pipeline connected to the pressure pipe 1 is set to test the airtightness of the measuring device.

[0066] If the sealing meets the requirements, then transfer container A to the fire simulation environment. At this time, the temperature of the fire simulation environment is room temperature. Check whether the first pressure measuring element 2 and the second pressure measuring element 3 show normal conditions.

[0067] If normal, proceed to the next step.

[0068] If it is abnormal, debug the first pressure measuring element 2 and the second pressure measuring element 3 until the display is normal;

[0069] If the sealing does not meet the requirements, repeat this step, reconnect the pressure pipe 1 and the container A, and check the sealing points or connectors, etc.;

[0070] The test is started, the fire simulation environment is adjusted to the fire condition, and the measured values ​​of the first pressure measuring element 2 and the second pressure measuring element 3 are stored and recorded by the controller 4. Specifically, the fire simulation environment can be a gas furnace or an oil pool.

[0071] The measuring method of the present invention can realize accurate measurement of the pressure in the inner container A1 under fire conditions.

[0072] In some preferred embodiments, the following steps are also included:

[0073] According to the model of container A, the model of pressure conducting tube 1 and the range and accuracy of the first pressure measuring element 2 and the second pressure measuring element 3 are determined; specifically, the diameter and length of pressure conducting tube 1 are selected based on the principle of minimizing the impact on the measured value of the first pressure measuring element 2; preferably, the smaller the diameter and the shorter the length of pressure conducting tube 1, the lower the impact on the measured value of the first pressure measuring element 2.

[0074] Specifically, the measuring ranges of the first pressure measuring element 2 and the second pressure measuring element 3 are determined according to the simulation calculation results. If the simulation calculation shows that the maximum pressure of container A during the heat resistance test is 500 kPa, the measuring range of the first pressure measuring element 2 should be 1000 kPa.

[0075] The pressure guiding tube 1 is connected to the first pressure measuring element 2;

[0076] Initial installation: connect the first pressure measuring element 2 and the second pressure measuring element 3 to the controller 4, turn on the controller 4 to test whether the controller 4, the first pressure measuring element 2 and the second pressure measuring element 3 are working properly.

[0077] If yes, proceed to the next step.

[0078] If no, repeat this step; that is, reconnect the first pressure measuring element 2 and the second pressure measuring element 3 and the controller 4, replace the seal if necessary, and then replace the first pressure measuring element 2 and the second pressure measuring element 3 and the controller 4 of the same specifications if necessary.

[0079] In some preferred embodiments, it also includes a device calibration step;

[0080] The steps for device calibration include:

[0081] Connect one side of the pressure pipe 1 connected to the container A to the standard pressure source;

[0082] A correction coefficient is obtained based on the pressure value of the standard pressure source and the measurement value of the first pressure measuring element 2; specifically, by setting different pressure values ​​of the standard pressure source, the correction coefficient under different pressures is obtained; specifically, the correction coefficient C=A / B, wherein A is the pressure value of the standard pressure source, and B is the measurement value of the first pressure measuring element 2.

[0083] The controller 4 records the model of the pressure-conducting tube 1 and the correction coefficient in a one-to-one correspondence. Based on the correspondence between the model of the corresponding pressure-conducting tube 1 and the correction coefficient by the controller 4 and the storage in the controller 4, it is convenient to measure the pressure-conducting tubes 1 of different specifications, that is, when measuring, the corresponding model of the pressure-conducting tube 1 can be selected.

[0084] Preferably, the calibrated pressure range should be no less than 95% of the measuring range of the first pressure measuring element 2 .

[0085] In some preferred embodiments, the first threshold is 1 / 500 / 10min; for example, after the pressure in container A1 reaches 500kPa, the difference in the measured values ​​of the first pressure measuring element 2 measured by the controller 4 at intervals of 10min is not greater than 1kPa, which is qualified; the specific value can be determined according to usage requirements.

[0086] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A device for measuring the internal pressure of a radioactive container under fire conditions, the container comprising an inner container and an outer container, the inner container being arranged in the outer container, characterized in that: The measuring device comprises a pressure pipe, a first pressure measuring element, a second pressure measuring element and a controller; One end of the pressure-conducting tube can extend into the inner container of the container, and the other end can extend out of the container and communicate with the first pressure measuring element. At least a portion of the pressure-conducting tube located outside the container is provided with a heat insulation structure; The first pressure measuring element is used to measure the pressure in the inner container; The second pressure measuring element is used to measure the ambient pressure; The controller is connected to the first load cell and the second load cell to obtain the gauge pressure in the inner container according to the measurement values ​​of the first load cell and the second load cell.

2. The device for measuring the internal pressure of a radioactive container under fire conditions according to claim 1, characterized in that: The heat insulation structure is an aerogel layer arranged on the surface of the pressure guiding pipe.

3. The device for measuring the internal pressure of a radioactive container under fire conditions according to claim 1, characterized in that: The pressure-conducting tube is made of stainless steel, with a diameter of 3 mm and a thickness of 0.5 mm.

4. The device for measuring the internal pressure of a radioactive container under fire conditions according to claim 1, characterized in that: The measuring range of the first pressure measuring element is 0 to 100 kPa; the measuring range of the second pressure measuring element is 0 to 10 kPa.

5. The device for measuring the internal pressure of a radioactive container under fire conditions according to claim 1, characterized in that: The pressure guiding pipe is sealed and connected to at least the inner container via a sealing connection piece; The sealing connector comprises a sealing member and a connector; The sealing member is sleeved and sealed on the pressure guiding pipe, and the sealing member abuts against the edge of the opening of the inner container for sealing; The connecting piece includes a fixing piece and a screw connection piece; The fixing member is used to be fixedly connected to the surface of the outer container and has a channel communicating with the inner part of the outer container; The screw connection piece is sleeved on the outside of the fixing piece and is screwed to the fixing piece; the pressure guiding tube is passed through the screw connection piece, so that when the screw connection piece is screwed to the fixing piece, the sealing piece abuts against the edge of the opening of the inner container for sealing.

6. The device for measuring the internal pressure of a radioactive container under fire conditions according to claim 5, characterized in that: The sealing member is a truncated cone-shaped structure, which is coaxially arranged with the pressure-guiding tube, and the side surface of the truncated cone structure abuts against the edge of the opening of the inner container for sealing.

7. The device for measuring the internal pressure of a radioactive container under fire conditions according to claim 6, characterized in that: The sealing member, the pressure-conducting tube and the container are all made of metal, and the thermal expansion coefficient of the sealing member is greater than the thermal expansion coefficients of the pressure-conducting tube and the container.

8. A measuring method using the measuring device described in any one of claims 1 to 7, characterized in that: The steps include: A preliminary sealing test is performed by filling the pressure pipe with gas until the measured pressure is reached and then stopping the gas supply. The controller records the measured value of the first pressure measuring element and calculates the decreasing rate of the measured value. If the measured value decreasing rate is greater than or equal to the first threshold, then check each connection until the measured value decreasing rate is less than the first threshold, If the measured value decreasing rate is less than the first threshold, proceed to the next step; The sealing performance is tested again by connecting the pressure pipe to the container and measuring the sealing performance of the measuring device again. If the sealing meets the requirements, the container is transferred to a fire simulation environment to check whether the first pressure measuring element and the second pressure measuring element are normal. If normal, proceed to the next step. If it is abnormal, then debug the first pressure measuring element and the second pressure measuring element until they are displayed as normal; If the sealing does not meet the requirements, repeat this step; The test is started, the fire simulation environment is adjusted to a fire condition, and the measurement values ​​of the first pressure measuring element and the second pressure measuring element are stored and recorded through a controller.

9. The measuring method according to claim 8, characterized in that: Before the preliminary sealing test, the following steps are also included: Determine the model of the pressure pipe and the range and accuracy of the first pressure measuring element and the second pressure measuring element according to the model of the container; A pressure pipe connection is used to connect the pressure pipe to the first pressure measuring element; Initial installation: connect the first load cell and the second load cell to the controller, turn on the controller to test whether the controller, the first load cell and the second load cell are working properly. If yes, proceed to the next step. If no, repeat this step.

10. The measuring method according to claim 8, characterized in that: Also included is a device calibration step; The device calibration step comprises: Connect one side of the pressure-conducting pipe connected to the container to a standard pressure source; Obtaining a correction coefficient according to the pressure value of the standard pressure source and the measurement value of the first pressure measuring element; The controller records the model of the pressure guiding tube and the correction coefficient in a one-to-one correspondence.

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