An on-line device and method for measuring pressure of fissile gas released from a fuel element

Abstract

This invention discloses an online measurement device and method for the release pressure of fission gas in fuel elements. The measurement device includes a fuel element, a fission gas dispersion and transmission channel, a coolant medium chamber, a bellows, an iron core, and a displacement monitor. The gas outlet of the fuel element is connected to the fission gas dispersion and transmission channel, and the end of the fission gas dispersion and transmission channel is connected to the coolant medium chamber. The bellows is located inside the coolant medium chamber. The two ends of the iron core are respectively connected to the bellows and the displacement monitor. The gas outlet channel of the fission gas dispersion and transmission channel is connected to the bellows. This invention can monitor the irradiation process in real time, thereby accurately reflecting the evolution of fuel and material properties and providing precise guidance for related designs.

Description

Technical Field

[0001] This invention relates to the field of fuel element irradiation technology, and more specifically to an online measurement device and method for the release pressure of fission gas in fuel elements. Background Technology

[0002] Fuel elements are the core components of a reactor core, and their performance is closely related to the reactor's safety, reliability, lifespan, and overall performance. Online measurement of fission gas release rate behavior parameters is a crucial step in evaluating fuel element performance. However, due to the demands of irradiation testing, the development of key irradiation testing technologies has not kept pace with these needs. Therefore, breakthroughs in online irradiation measurement technology and measurement device design are urgently needed.

[0003] Monitoring irradiation behavior is a highly coupled process. Online measurement of irradiation behavior not only requires research on the irradiation behavior itself, but also involves the measurement of environmental factors such as temperature and flow rate, the measurement of nuclear parameters such as neutron flux and gamma detection, and the development of instrumented irradiation devices. Given that online measurement of irradiation behavior is related to multiple factors, current methods for online measurement of fuel element irradiation behavior, which still rely on detecting the release pressure of fission gases after irradiation, are clearly insufficient to meet the needs of irradiation behavior monitoring. They cannot accurately reflect the evolution of fuel and material properties, nor can they provide precise guidance for related designs.

[0004] Therefore, this patent application is filed. Summary of the Invention

[0005] This invention provides an online measurement device and method for the release pressure of fission gas in fuel elements, which solves the problem that existing online monitoring of the release pressure of fission gas in fuel elements is performed after irradiation, resulting in inaccurate measurement and failure to accurately reflect the evolution process of fuel and material properties.

[0006] The first objective of this invention is to provide an online measurement device for the release pressure of fission gas in a fuel element, comprising a fuel element, a fission gas dispersion and transmission channel, a coolant medium chamber, a bellows, an iron core, and a displacement monitor. The gas outlet of the fuel element is connected to the fission gas dispersion and transmission channel, the end of the fission gas dispersion and transmission channel is connected to the coolant medium chamber, the bellows is located inside the coolant medium chamber, the two ends of the iron core are respectively connected to the bellows and the displacement monitor, and the gas outlet channel of the fission gas dispersion and transmission channel is connected to the bellows.

[0007] In an optional embodiment, the fission gas dispersion and transmission channel includes a gas dispersion layer and a fission gas transmission channel, the gas outlet of the fuel element is connected to the gas dispersion layer, and the gas dispersion layer is connected to the fission gas transmission channel.

[0008] In an optional embodiment, the fission gas transmission channel is a unidirectional transmission channel.

[0009] In an optional embodiment, the coolant medium chamber is filled with a coolant medium, which is either gas or water;

[0010] The coolant chamber is provided with a base at its end, and the displacement monitor is fixed on the base.

[0011] In an optional embodiment, the fission gas transmission channel is provided with multiple outflow holes, each of which is connected to a corresponding gas flow channel. The gas channels have different apertures and are nested together in sequence. The gas flow channel with the smallest aperture is connected to the bellows located at the end away from the fuel element, and the gas flow channel with the largest aperture is connected to the bellows closest to the fuel element. Each gas flow channel is connected to a bellows. A flow passage is provided between two adjacent bellows. The flow passage is open at one end and closed at the other end. Each flow passage is connected to a bellows closest to the fuel element.

[0012] The bellows located at the end, away from the fuel element, is connected to the iron core.

[0013] In an optional embodiment, the air passage is an annular air passage, and three bellows are provided.

[0014] In an optional embodiment, the bellows is a negative pressure differential bellows.

[0015] In an optional embodiment, the corrugated pipe includes a first end ring, a corrugated inner sleeve, an outer protective tube, and a second end ring. One end of the outer protective tube is slidably connected to the first end ring, and the other end is slidably connected to the second end ring. Both the first and second end rings are provided with a sliding protrusion, and the two sliding protrusions overlap and slide in cooperation. A cavity is formed between the outer protective tube, the first end ring, and the second end ring. The corrugated inner sleeve is disposed in the cavity, and one end of the corrugated inner sleeve is connected to the first end ring, and the other end is connected to the second end ring.

[0016] The second objective of this invention is to provide a method for online measurement of fission gas release pressure in fuel elements, which is implemented using the online measurement device for fission gas release pressure in reactor fuel elements as described above, and monitors the fission gas release pressure during the irradiation of fuel elements.

[0017] In an optional embodiment, it includes:

[0018] The multi-stage fission gas generated by the irradiation of the fuel element enters the multi-stage bellows through the fission gas diffusion and transmission channel. The displacement of the bellows causes the iron core to have a relative displacement with respect to the displacement monitor, so as to monitor the pressure change of the fission gas released during the irradiation operation.

[0019] The fission gas enters through the gas flow channel and is sealed in the chamber formed by the corrugated pipes of each stage and the corresponding annular gas channel, so as to concentrate the internal pressure formed by the fission gas of each stage to the end of the corrugated pipe far away from the fuel element.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] (1) The embodiment of the present invention provides an online measurement device for the fission gas release pressure of fuel elements, which can monitor the fission gas release pressure in real time during the irradiation process. It can monitor the changes in environmental factors such as temperature and flow rate, as well as the changes in nuclear parameters such as neutron flux and gamma detection during the irradiation process, in real time, so as to accurately reflect the evolution process of fuel and material properties and provide precise guidance for related designs.

[0022] (2) The embodiment of the present invention provides an online measuring device for the release pressure of fission gas of fuel element, which integrates fuel element and measuring device into one unit, and can collect radioactive Pu-238 and other toxic gases after irradiation to prevent gas leakage and diffusion.

[0023] (3) The online measurement device for the release pressure of fission gas in fuel elements provided in this embodiment of the invention can collect the gas in bellows at different levels through multiple channels for reversing gas flow, and display all loads in series in the displacement of the core, which has a significant amplification effect on the displacement and improves the measurement accuracy. Moreover, the gas / water chamber of this invention can improve the applicability of the device and is suitable for use in a variety of core media. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0025] Figure 1 This is a schematic diagram of a device for online measurement of the release pressure of fission gas in fuel elements, provided in an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the multi-channel gas flow and gas diffusion method in the online measurement device of this invention.

[0027] Figure 3 This is a schematic diagram of the bellows structure of the online measurement device according to an embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram of the iron core of the online measuring device according to an embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram of the probe of the online measurement device according to an embodiment of the present invention.

[0030] Names of the components in the attached diagram:

[0031] 1-Fuel element, 2-Gas dispersion layer, 3-Fission gas transmission channel, 4-First bellows, 41-First end ring, 42-Corrugated inner sleeve, 43-Outer protective tube, 44-Second end ring, 45-Sliding convexity, 5-Flow passage, 6-Second bellows, 7-Coolant medium chamber, 8-Third bellows, 9-Iron core, 91-Magnetic core, 92-Stud, 10-Displacement monitor, 101-Probe, 1011-Cable, 1012-Sealing head, 1013-Body, 11-Base, 12-Outlet hole, 13-Gas flow channel, 14-Flow passage. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0035] In the description of the embodiments of this application, the terms "center", "upper", "lower", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inner", "outer", "front", "rear", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this application and to simplify the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0036] In the description of this invention, unless otherwise explicitly specified and limited, the terms "set up," "have," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0037] Example 1:

[0038] An online measurement device for the release pressure of fission gas in fuel elements, such as Figure 1 As shown, it includes a fuel element 1, a fission gas dispersion and transmission channel, a coolant medium chamber 7, a bellows, an iron core 9, and a displacement monitor 10.

[0039] The fission gas dispersion and transmission channel includes a gas dispersion layer 2 and a fission gas transmission channel 3. The gas outlet of the fuel element 1 is connected to the gas dispersion layer 2, through which the irradiated fission gas is dispersed and released. The gas dispersion layer 2 is connected to the fission gas transmission channel 3, which is located at the rear end of the gas dispersion layer 2 and is used to transport the fission gas to the bellows. At the rear end of the fission gas transmission channel 3 is a coolant medium chamber 7, in which the bellows is located. The coolant medium chamber 7 is filled with coolant medium to cool the fission gas and prevent temperature from affecting the volume change of the bellows. One end of the iron core 9 is connected to the bellows, and the other end is connected to a displacement monitor 10. The iron core 9 is fixedly connected to the end of the bellows but can move relative to the displacement monitor 10.

[0040] In operation, fuel element 1 is irradiated, and the resulting fission gas is transported into a bellows where a coolant medium cools it. As the fission gas continuously enters the bellows, pressure changes occur within the bellows, causing radial displacement of the bellows and thus moving the iron core 9. The displacement of the iron core 9 is directly detected by a displacement monitor 10, which uses the detected displacement change signal to provide feedback on the fission gas release pressure, enabling real-time online monitoring during the irradiation process. Changes in environmental factors such as temperature and flow rate, as well as changes in nuclear parameters such as neutron flux and gamma detection, can all be monitored promptly during irradiation, accurately reflecting the evolution of fuel and material properties and providing precise guidance for related designs.

[0041] In this embodiment of the invention, the fuel element 1 and the measuring device are integrated into a whole, which can perform online real-time monitoring of the release pressure of fission gas from the reactor fuel element without having to perform the measurement after irradiation. The structure is reasonable, safe and reliable, and can operate stably for a long time.

[0042] Furthermore, the fission gas transmission channel 3 is a unidirectional transmission channel, which can be implemented using a one-way valve combined with a pipeline. With unidirectional transmission, the fission gas can only be transmitted in the direction of the bellows and will not flow in the reverse direction, making the measurement structure more accurate and reliable.

[0043] In this embodiment of the invention, the coolant medium chamber 7 is filled with a coolant medium, which can be gas or water, forming a gas chamber or a water chamber. For example, in a gas-cooled reactor, the corresponding chamber is a gas chamber, and the pressure in the gas chamber is the gas coolant pressure. The pressure difference between the pressure inside the bellows and the gas coolant pressure is the measured value. External pressure compensation correction needs to be considered when calculating the gas release amount. In a pressurized water reactor, the corresponding chamber is a water chamber, and the pressure in the water chamber is the primary water pressure. This design allows for a wider range of applications and enhanced adaptability. A base 11 is also provided at the end of the coolant chamber, and the displacement monitor 10 is fixed to the base 11.

[0044] This embodiment enables real-time online monitoring during the irradiation process, accurately reflecting the evolution of fuel and material properties. It also improves the applicability of the device, making it suitable for various reactor core media.

[0045] Example 2:

[0046] Based on Embodiment 1, the fission gas transmission channel 3 is further provided with multiple outflow holes 12, all of which are parallel and have a unidirectional gas outflow structure. Each outflow hole 12 has a corresponding gas flow channel 13 connected to its side. The gas flow channel 13 is located inside a corrugated pipe, and the diameters of each gas channel are different. The gas channels are nested together in sequence. The gas flow channel 13 with the smallest diameter is connected to the corrugated pipe located at the farthest end, which is farthest from the fuel element 1 and is connected to the iron core 9. The gas flow channel 13 with the largest diameter is connected to the corrugated pipe closest to the fuel element 1. Each gas flow channel 13 is connected to a corrugated pipe. In this way, after the fuel element 1 is irradiated, the fission gas enters each corrugated pipe through the outflow hole 12 and the corresponding gas flow channel 13. A flow channel 5 is provided between two adjacent corrugated pipes. The flow channel 5 is open at one end and closed at the other. The open end connects to a corrugated pipe near the fuel element 1, while the closed end connects to the other corrugated pipe. Thus, under the action of the unidirectional outflow orifice 12, the fission gas is confined within the space between the various corrugated pipes, the gas flow channel 13, and the flow channel 5. After irradiation, radioactive Pu-238 and other toxic gases can also be collected to prevent gas leakage and diffusion.

[0047] Better yet, the air passage 5 is configured as an annular air passage, and three corrugated pipes are provided, namely a first corrugated pipe 4, a second corrugated pipe 6, and a third corrugated pipe 8. The first corrugated pipe 4 is close to the gas dispersion layer 2, and the third corrugated pipe 8 is connected to the iron core 9.

[0048] The fission gas generated by fuel element 1, after passing through gas dispersion layer 2 and gas unidirectional channel, exhibits multiple gas flow paths and gas diffusion patterns, as shown in the figure. Figure 2 In this system, gas released from the middle channel of the unidirectional gas channel is axially transmitted to the third bellows 8 via the central gas flow channel (i.e., the gas channel with the smallest aperture, connected to the third bellows 8), while gas released from the outer channels is axially transmitted to the bellows via the outer annular flow channel 5. Thus, the internal pressure generated by the multi-stage fission gas ultimately concentrates on the base 11 to the right of the third bellows 8, generating a force and displacement to the right. The force and displacement on the base 11 are the sum of the multi-stage series loads. After being connected in series by the three bellows, the load is concentrated on the iron core 9, generating radial displacement, which is directly measured by the displacement monitor 10 fixed to the base 11.

[0049] In this embodiment, the fission gas can be collected in bellows at different levels through multi-channel reversing gas channels, and all loads are displayed in series in the displacement of the iron core 9, which amplifies the displacement and greatly improves the measurement accuracy.

[0050] Example 3:

[0051] Based on Embodiment 2, the corrugated pipe is a negative pressure differential corrugated pipe. The corrugated pipe includes a first end ring 41, a corrugated inner sleeve 42, an outer protective tube 43, and a second end ring 44. One end of the outer protective tube 43 is slidably connected to the first end ring 41, and the other end is slidably connected to the second end ring 44. Both the first end ring 41 and the second end ring 44 are provided with a sliding protrusion 45. The two sliding protrusions 45 overlap and slide in a staggered manner. A cavity is formed between the outer protective tube 43, the first end ring 41, and the second end ring 44. The corrugated inner sleeve 42 is disposed in the cavity. One end of the corrugated inner sleeve 42 is connected to the first end ring 41, and the other end is connected to the second end ring 44. The sliding cavity has a reserved axial displacement space of 10mm (range) for detecting the elongation of the corrugated inner sleeve 42. The outer protective tube 43 is used to support and protect the corrugated inner sleeve 42 and limit its radial displacement, so that its axial elongation is approximately linearly distributed with respect to the internal pressure, which is beneficial for calibration and standardization of the measurement work.

[0052] The structure of the iron core 9 in this embodiment is shown below. Figure 4 The LVDT core 9 includes a magnetic core 91 and a stud 92, while the structure of the displacement monitor 10 is shown below. Figure 5 The system includes an LVDT probe 101, which comprises a cable 1011, a sealing head 1012, and a body 1013. The sealing head 1012 is connected and fixed to the body 1013, and the stud 92 of the iron core 9 is fixedly engaged with the sealing head 1012.

[0053] This invention provides an online measurement device for the release pressure of fission gas from reactor fuel elements. It collects the fission gas released from fuel element 1 during irradiation and simultaneously measures the pressure of the collected fission gas online. The invention also provides methods for loading and applying the measurement device in both gaseous and aquatic environments, demonstrating its applicability.

[0054] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An online measuring device for the release pressure of fission gas in fuel elements, characterized in that, The device includes a fuel element (1), a fission gas dispersion and transmission channel, a coolant medium chamber (7), a bellows, an iron core (9), and a displacement monitor (10). The gas outlet of the fuel element (1) is connected to the fission gas dispersion and transmission channel. The end of the fission gas dispersion and transmission channel is connected to the coolant medium chamber (7). The bellows is located inside the coolant medium chamber (7). The two ends of the iron core (9) are respectively connected to the bellows and the displacement monitor. The gas outlet channel of the fission gas dispersion and transmission channel is connected to the bellows.

2. The online measuring device for the release pressure of fission gas in fuel elements according to claim 1, characterized in that, The fission gas dispersion and transmission channel includes a gas dispersion layer (2) and a fission gas transmission channel (3). The gas outlet of the fuel element (1) is connected to the gas dispersion layer (2), and the gas dispersion layer (2) is connected to the fission gas transmission channel (3).

3. The online measuring device for the release pressure of fission gas in fuel elements according to claim 2, characterized in that, The fission gas transmission channel (3) is a unidirectional transmission channel.

4. The online measuring device for the release pressure of fission gas in fuel elements according to claim 2, characterized in that, The coolant medium chamber (7) is filled with a coolant medium, which is either gas or water; The coolant chamber is provided with a base (11) at its end, and the displacement monitor (10) is fixed on the base (11).

5. The online measuring device for the release pressure of fission gas in fuel elements according to claim 2, characterized in that, The fission gas transmission channel (3) is provided with multiple outflow holes (12), each of which is connected to a gas flow channel (13). The gas flow channels (13) have different apertures and are nested together in sequence. The gas flow channel (13) with the smallest aperture is connected to the corrugated pipe located at the end away from the fuel element (1), and the gas flow channel (13) with the largest aperture is connected to the corrugated pipe closest to the fuel element (1). Each of the gas flow channels (13) is connected to a corrugated pipe. A flow passage (5) is provided between two adjacent corrugated pipes. The flow passage (5) is open at one end and closed at the other end. Each of the flow passages (5) is connected to a corrugated pipe close to the fuel element (1). The bellows located at the end, away from the fuel element (1), is connected to the iron core (9).

6. The online measuring device for the release pressure of fission gas in fuel elements according to claim 5, characterized in that, The air passage (5) is an annular air passage, and three corrugated pipes are provided.

7. The online measuring device for the release pressure of fission gas in fuel elements according to claim 1, characterized in that, The bellows is a negative pressure differential bellows.

8. The online measuring device for the release pressure of fission gas in fuel elements according to claim 1, characterized in that, The corrugated pipe includes a first end ring (41), a corrugated inner sleeve (42), an outer protective tube (43), and a second end ring (44). One end of the outer protective tube (43) is slidably connected to the first end ring (41), and the other end is slidably connected to the second end ring (44). A sliding protrusion (45) is provided on both the first end ring (41) and the second end ring (44). The two sliding protrusions (45) overlap and slide together. A cavity is formed between the outer protective tube (43), the first end ring (41), and the second end ring (44). The corrugated inner sleeve (42) is located in the cavity. One end of the corrugated inner sleeve (42) is connected to the first end ring (41), and the other end is connected to the second end ring (44).

9. A method for online measurement of fission gas release pressure in reactor fuel elements, characterized in that, The fission gas release pressure is monitored during the irradiation of the fuel element (1) using an online measurement device for fission gas release pressure of reactor fuel element as described in any one of claims 1 to 8.

10. A method for online measurement of fission gas release pressure in reactor fuel elements according to claim 9, characterized in that, include: The multi-stage fission gas generated by the irradiation of the fuel element (1) enters the multi-stage bellows through the fission gas diffusion transmission channel. The displacement of the bellows causes the iron core (9) to generate a relative displacement with respect to the displacement monitor (10) in order to monitor the pressure change of the fission gas released during the irradiation operation. The fission gas enters through the gas flow channel (13) and is sealed in the chamber formed by the corrugated pipes of each stage and the corresponding annular gas channel, so as to concentrate the internal pressure formed by the fission gas of each stage to the end of the corrugated pipe far away from the fuel element (1).

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