Offline Sip Leak Test Equipment Detector System

Abstract

The present invention discloses a detector system for an offline sniffing and leakage test device, which includes a shielding body and a gas detection device provided in the shielding body. The gas detection device includes a sampling chamber provided in the shielding body, a first detection component provided on one side of the sampling chamber, and a second detection component provided on the other side of the sampling chamber. The first detection component is inserted into the sampling chamber to detect the activity concentration values of Xe-133 and Kr-85 by detecting beta rays, and the second detection component is inserted into the sampling chamber to detect the activity concentration value of Xe-133 by detecting gamma rays. The detector system for the offline sniffing and leakage test device can be used to measure the activity concentrations of Kr-85 and Xe-133 in the pipeline of the sniffing and leakage system and output the energy spectrum information of Kr-85 and Xe-133. Considering the relatively high gamma irradiation background level at the site, a special auxiliary detector is also provided to reduce the interference of environmental background fluctuations. Moreover, the detector system for the offline sniffing and leakage test device has high detection sensitivity and strong anti-interference ability, and can realize the detection of slightly defective components.

Description

Technical Field

[0001] The invention relates to the field of nuclear power plant maintenance devices, and particularly to a detector system for an offline leak testing equipment. Background Art

[0002] During reactor refueling, an offline leak testing equipment detector is required to monitor the activity of radioactive inert gases in the monitoring system and evaluate the integrity of the fuel assembly cladding. Traditional offline leak testing detectors have problems such as low detection sensitivity and susceptibility to external gamma field interference, which are not conducive to detecting fuel assemblies with minor defects. In addition, due to the short half-life of the detected Xe-133, it is impossible to detect the cladding integrity of the repaired fuel assemblies and the fuel assemblies stored for a long time. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a detector system for an offline leak testing equipment.

[0004] The technical solution adopted by the present invention to solve its technical problem is: to construct a detector system for an offline leak testing equipment, which includes a shielding body and a gas detection device disposed in the shielding body;

[0005] The gas detection device includes a sampling chamber disposed in the shielding body, a first detection component disposed on one side of the sampling chamber, and a second detection component disposed on the other side of the sampling chamber;

[0006] The first detection component is inserted into the sampling chamber to detect the activity concentration values of Xe-133 and Kr-85 by detecting beta rays;

[0007] The second detection component is inserted into the sampling chamber to detect the activity concentration value of Xe-133 by detecting gamma rays.

[0008] In some embodiments, the first detection component includes a first probe inserted into the sampling chamber for measuring the beta ray activity concentration value in the sampling chamber, a second probe for compound subtraction of the count caused by the environmental background, and a third probe for measuring the beta ray activity by the current integration method;

[0009] A shielding plate for shielding beta rays in radioactive inert gases is provided at the bottom of the second probe.

[0010] In some embodiments, the second detection component includes a first detection head for energy spectrum acquisition of Xe-133 in the sampling chamber and measurement of the corresponding activity concentration value, and a second detection head for avoiding count interference caused by the environmental background;

[0011] An attenuation layer is provided at the bottom of the first detection head;

[0012] A barrier layer is provided between the second detection head and the first detection head and the sampling chamber respectively;

[0013] Radioactive source inspection trays are provided on both the first detection head and the second detection head.

[0014] In some embodiments, the first probe, the second probe, and the third probe are all β probes;

[0015] Both the first detection head and the second detection head are γ probes composed of sodium iodide crystals.

[0016] In some embodiments, the first probe and the second probe act together to measure the activity concentration values of Kr-85 and Xe-133 within the range of 3 3.7E+03 Bq / m 3 to 3.7E+09 Bq / m;

[0017] The third probe is used to measure the activity concentration values of Kr-85 and Xe-133 within the range of 3 3.7E+07 Bq / m 3 to 3.7E+12 Bq / m;

[0018] The first detection head and the second detection head act together to measure the activity concentration value of Xe-133 within the range of 3 3.7E+04 Bq / m 3 to 3.7E+010 Bq / m.

[0019] In some embodiments, the gas detection device further includes a positioning frame, a carbon fiber layer provided in the positioning frame for strengthening the positioning frame, a sealing ring provided on the sampling chamber, and a processing circuit provided on the positioning frame.

[0020] In some embodiments, the shielding body includes a plurality of shielding block units, and the plurality of shielding block units are connected together by fasteners;

[0021] A lifting ring is further provided on the shielding body.

[0022] In some embodiments, the offline leak test equipment detector system further includes a transport cart for carrying the shielding body;

[0023] A shock pad is provided between the shielding body and the transport cart.

[0024] In some embodiments, the offline leak test equipment detector system further includes a ventilation circuit, and the ventilation circuit includes an air inlet connected to the sampling chamber and an air outlet connected to the sampling chamber;

[0025] A filter is provided between the air inlet and the sampling chamber;

[0026] A sampling pump is provided between the air outlet and the sampling chamber.

[0027] In some embodiments, the detector system of the offline sniff leak test equipment further includes an electrical box connected to the gas detection device and a host computer connected to the electrical box.

[0028] Implementing the present invention has the following beneficial effects: The detector system of the offline sniff leak test equipment includes: a shielding body and a gas detection device provided in the shielding body. The gas detection device includes a sampling chamber provided in the shielding body, a first detection component provided on one side of the sampling chamber, and a second detection component provided on the other side of the sampling chamber. The first detection component is inserted into the sampling chamber to detect the activity concentration values of Xe-133 and Kr-85 by detecting beta rays; the second detection component is inserted into the sampling chamber to detect the activity concentration value of Xe-133 by detecting gamma rays. The detector system of the offline sniff leak test equipment can be used to measure the activity concentrations of Kr-85 and Xe-133 in the pipeline of the sniff leak system and output the energy spectrum information of Kr-85 and Xe-133. Considering the relatively high gamma irradiation background level on site, a dedicated auxiliary detector is also provided to reduce the interference of environmental background fluctuations. Moreover, the detector system of the offline sniff leak test equipment has high detection sensitivity and strong anti-interference ability, and can detect slightly defective components. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the present invention, the present invention will be further described below in conjunction with the drawings and embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0030] Figure 1 is a schematic structural diagram of the detector system of the offline sniff leak test equipment in some embodiments of the present invention;

[0031] Figure 2 is a schematic structural diagram of the gas detection device in some embodiments of the present invention;

[0032] Figure 3 is a schematic structural diagram of the gas detection device in another direction in some embodiments of the present invention;

[0033] Figure 4 is a schematic structural diagram of the shielding body in some embodiments of the present invention;

[0034] Figure 5It is a schematic diagram of the functional structure of the detector system of the offline leak test equipment in some embodiments of the present invention. Detailed implementation manners

[0035] In order to have a clearer understanding of the technical features, objectives, and effects of the present invention, the specific implementation manners of the present invention will now be described in detail with reference to the accompanying drawings. In the following description, it should be understood that the orientation or positional relationships indicated by "front", "rear", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail", etc. are based on the orientation or positional relationships shown in the accompanying drawings and are constructed and operated in a specific orientation, and are only for the convenience of describing the technical solution, rather than indicating that the indicated device or element must have a specific orientation, so it should not be construed as a limitation to the present invention.

[0036] It should also be noted that unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection", "fixation", "setting", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements. When an element is referred to as being "above" or "below" another element, the element can be "directly" or "indirectly" located above the other element, or there may also be one or more intermediate elements. Terms such as "first", "second", "third", etc. are only for the convenience of describing the technical solution and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first", "second", "third", etc. may explicitly or implicitly include one or more of such features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] Please refer to Figures 1 to 5 , which is a detector system of an offline leak test equipment in some embodiments of the present invention. It is used to detect defective fuel assemblies during the refueling outage of a nuclear power plant to determine whether the fuel assembly is damaged. The offline leak test equipment detector system includes a shielding body 1 and a gas detection device 2 disposed in the shielding body 1. The gas detection device 2 includes a sampling chamber 21 disposed in the shielding body 1, a first detection component 22 disposed on one side of the sampling chamber 21, and a second detection component 23 disposed on the other side of the sampling chamber. The first detection component 22 is inserted into the sampling chamber 21 to detect the activity concentration values of Xe-133 and Kr-85 by detecting beta rays; the second detection component 23 is inserted into the sampling chamber 21 to detect the activity concentration value of Xe-133 by detecting gamma rays.

[0038] In some embodiments, the first detection component 22 includes a first probe, a second probe, and a third probe, and a shielding plate is provided at the bottom of the second probe. Specifically, the first probe and the second probe may have the same shape and size, and the sizes of the first probe and the second probe are larger than the size of the third probe, and the first probe and the second probe may be designed symmetrically left and right. Among them, the first probe is used to measure the total β radioactivity concentration value in the sampling chamber 21, and the second probe is used to perform composite deduction on the count caused by the environmental background. Preferably, the third probe can measure the activity concentrations of Xe-133 and Kr-85 by the current integration method. Further, the shielding plate may preferably be a steel plate with a thickness of 1 mm, which is used to shield the β rays in the radioactive inert gas, thereby ensuring the accuracy and stability of the detection of the first detection component 22. Among them, the first probe and the second probe act together to measure the activity concentration values of Kr-85 and Xe-133 within the range of 3.7E+03 Bq / m 3 ~3.7E+09 Bq / m 3 The activity concentration values of Kr-85 and Xe-133 within the range, and the third probe is used to measure the activity concentration values of Kr-85 and Xe-133 within the range of 3.7E+07 Bq / m 3 ~3.7E+12 Bq / m 3 The activity concentration values of Kr-85 and Xe-133 within the range.

[0039] In some embodiments, the second detection component 23 includes a first detection head and a second detection head. An attenuation layer is provided at the bottom of the first detection head, and a barrier layer is provided between the second detection head and the first detection head and the sampling chamber 21 respectively. Understandably, the first detection head is used to collect the energy spectrum of Xe-133 in the sampling chamber 21 and measure the corresponding activity concentration value, and the second detection head is used to avoid the counting interference caused by the environmental background. Further, the attenuation layer may preferably be a stainless steel absorber sheet, which can be used to prevent the detector from being saturated by the high activity concentration of Xe-133. And to achieve a wide γ detection range, the stainless steel absorber sheet can shield part of the energy according to its different thicknesses, so as to ensure that the first detection head will not exceed the range during detection. The actual value of the activity concentration of Xe-133 can be calculated inversely according to the measurement result of the first detection head and the thickness of the stainless steel absorber sheet, ensuring the accuracy and stability of the detection of the first detection head. Further, the barrier layer may be a 10-mm-thick lead plate, which enables the second detection head to measure the value of the external γ background. The first detection head and the second detection head work together to reduce the background interference and jointly complete the measurement of the activity concentration value of Xe-133. Still further, radiation source inspection trays are provided on both the first detection head and the second detection head, which are used to inspect the first detection head and the second detection head to prevent measurement deviations of the first detection head and the second detection head, ensuring the effectiveness and stability of the detection of the second detection component 23. Among them, the first detection head and the second detection head work together to measure 3.7E+04 Bq / m 3 ~3.7E+010 Bq / m 3 The activity concentration value of Xe-133 within the range.

[0040] Among them, the first probe, the second probe and the third probe are all β probes. The β probe can be made of plastic scintillator material. The β probe made of plastic scintillator material has high luminous efficiency, good linearity, short luminous decay time, and good processing performance, and the refractive index is appropriate. The first detection head and the second detection head are both γ probes. The γ probe can be made of sodium iodide crystal material. The γ probe made of sodium iodide crystal material has the advantages of high detection efficiency, high sensitivity, large counting capacity, etc., and has energy resolution ability, and can be applied to occasions such as monitoring the radiation level in the environment and radioactive nuclide identification.

[0041] Such as Figure 3As shown, in some embodiments, the gas detection device 2 further includes a positioning frame 24, a carbon fiber layer 25 provided in the positioning frame 24 for fixing the positioning frame 24, a sealing ring 26 provided on the sampling chamber 21, and a processing circuit 27 provided on the positioning frame 24. It can be understood that the positioning frame 24 is used to provide a positioning and supporting structure for the sampling chamber 21, the first detection component 22, and the second detection component 23. The carbon fiber layer 25 has high strength and rigidity, and can also resist corrosion, be acid and alkali resistant, and high temperature resistant, making the positioning frame 24 more firm and reliable. The sealing ring 26 is used to prevent air leakage in the sampling chamber 21, ensuring the sealing performance of the gas detection device 2. Among them, the processing circuit 27 is used to receive the measurement values from the first detection component 22 and the second detection component 23, and after processing, transmit signals to the control system. The processing circuit 27 and the first detection component 22 and the second detection component 23 can be electrically connected through wire connections.

[0042] As Figure 4 shown, further, the shielding body 1 includes a number of shielding block units 11, and the number of said shielding block units 11 are connected together by fasteners. Preferably, the shielding body 1 can be made of a 50 mm thick lead plate plus a 10 mm thick 304 stainless steel plate, which is used to reduce the interference of the external gamma field and reduce the measurement background value. It can be understood that for convenient on-site transportation, the shielding body 1 adopts a split design. The shielding body 1 can be split into 11 pieces, and the weight of each piece ranges from 50 kg to 65 kg. Further, the number of said shielding block units 11 can be bolt-fixed by fasteners, which is convenient for disassembly and improves work efficiency. In some other embodiments, the number of splits of the shielding block unit 11 can be adjusted according to actual situations, and the number of said shielding block units 11 can also be connected through slots or through positioning pins, which are not specifically limited here. Preferably, the shielding body 1 is also provided with a lifting ring 12 for convenient hoisting and transportation.

[0043] Among them, the detector system of the offline leak test equipment further includes a transport trolley 3 for carrying the shielding body 1, and a shock pad 31 is provided between the shielding body 1 and the transport trolley 3. It can be understood that for convenient transportation and transfer, the shielding body 1 is installed on the transport trolley 3 and moved. Preferably, the transport trolley 3 can be made of solid steel, with a load capacity of 1500 kg and dimensions of 652 mm * 453 mm * 740 mm. Further, the shock pad 31 can provide a buffering effect for the shielding body 1 during transportation, making the shielding body 1 not easily damaged during transportation.

[0044] In some embodiments, the detector system of the offline leak test equipment further includes a ventilation circuit 4. The ventilation circuit 4 includes an air inlet 41 connected to the sampling chamber 21 and an air outlet 42 connected to the sampling chamber 21. It can be understood that the air inlet 41 and the air outlet 42 are jointly connected to the sampling chamber 21 to form an air flow channel for gas circulation with the sampling chamber 21. Among them, the air inlet 41 and the air outlet 42 can be provided on the same side of the sampling chamber 21. In some other embodiments, the air inlet 41 and the air outlet 42 can also be provided on the opposite sides of the sampling chamber 21, which can be adjusted according to the actual situation. Further, a filter 43 is provided between the air inlet 41 and the sampling chamber 21. The filter 43 can be used to intercept various contaminants such as aerosols, iodine, and abrasive particles in the gas entering the ventilation circuit 4 through the air inlet 41, ensuring the purity of the gas entering the sampling chamber 21 and the accuracy of the detection by the gas detection device 2. Still further, a sampling pump 44 is provided between the air outlet 42 and the sampling chamber 21. The sampling pump 44 is used to extract the gas in the sampling chamber 21 and discharge it through the air outlet 42.

[0045] In some embodiments, the ventilation circuit 4 may also be provided with a flow meter, a pressure gauge, and a control valve. The flow meter can be used to measure the magnitude of the flow value on the ventilation circuit 4. The pressure gauge can be used to measure the magnitude of the flow value on the ventilation circuit 4. The control valve can be used to control the pressure and flow on the ventilation circuit 4. Preferably, quick connectors are used for connecting the pipes on the ventilation circuit 4, which can improve the installation efficiency and facilitate disassembly.

[0046] Further, the detector system of the offline leak test equipment further includes an electrical box 5 connected to the gas detection device 2 and a host computer 6 connected to the electrical box 5. It can be understood that the electrical box 5 is used for power supply and communication conversion of the gas detection device 2, and it is small in size and convenient to use. The host computer 6 can be used to receive the signals transmitted from the processing circuit 27 and can monitor the performance status of the gas detection device 2 in real time.

[0047] Among them, in addition to the direct deduction compensation method, the background compensation method of the detector system of the offline leak test equipment also adopts a dynamic composite measurement compensation method. The direct deduction method is used under low environmental dose rate conditions, and the composite measurement compensation method is automatically adopted under high dose rates.

[0048] It can be understood that the beneficial effects of the detector system of the offline leak test equipment are as follows:

[0049] 1. The detector system of the offline leak test equipment has a simple structure, reasonable design, and is easy to implement;

[0050] 2. The detector system of this offline leak and sip test equipment can not only measure the total β activity concentration of inert gas, but also measure the activity concentrations of Kr-85 and Xe-133. It can reach the lower limit of Kr measurement of 3.7E+03 Bq within 120 s and respond to the lower limit of Xe-133 measurement of 3.7E+04 Bq within 300 s, with a fast reaction efficiency, thus improving the measurement efficiency;

[0051] 3. The detector system of this offline leak and sip test equipment adopts a reasonable design of gas detection device. Using two identical detectors, one measures the activity concentration value of the gas and the other measures the environmental dose rate, excluding external interference and reducing the measurement background. It can ensure the normal operation of the equipment under a γ field of 200 μGy / h, ensuring the stability and accuracy of the measurement by the gas detection device 2;

[0052] 4. The first detection component 22 adopts a multi-detector design, achieving a measurement range of 12 orders of magnitude. A stainless steel absorber is also provided in the second detection component 23 to achieve a wide γ measurement range, improving the adaptability of the detector system of this offline leak and sip test equipment;

[0053] 5. The shielding body 1 of the detector system of this offline leak and sip test equipment adopts a split design, which is convenient for handling and on-site installation, saving the time for disassembly, assembly and handling, and reducing the probability of danger to the staff;

[0054] 6. The detector system of this offline leak and sip test equipment has high detection sensitivity and strong anti-interference ability, and can detect slightly defective components. It can detect Kr-85 with a long half-life period, enhancing the detection ability for the fuel components after repair and the spent fuel components in long-term storage.

[0055] It can be understood that the above embodiments only represent the preferred implementation modes of the present invention, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention; it should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can also be made, which all belong to the protection scope of the present invention; therefore, all equivalent transformations and modifications made to the scope of the claims of the present invention shall fall within the scope covered by the claims of the present invention.

Claims

1. An off-line leak test equipment detector system, characterized in that: include: A shielding body (1) and a gas detection device (2) disposed in the shielding body (1); The gas detection device (2) comprises a sampling chamber (21) arranged in a shielding body (1), a first detection component (22) arranged on one side of the sampling chamber (21), and a second detection component (23) arranged on the other side of the sampling chamber (21); The first detection component (22) is inserted into the sampling chamber (21) to detect the activity concentration values of Xe-133 and Kr-85 by detecting beta rays; The second detection component (23) is inserted into the sampling chamber (21) to detect the activity concentration value of Xe-133 by detecting gamma rays; The first detection component (22) includes a first probe inserted into the sampling chamber (21) for measuring the beta ray activity concentration value in the sampling chamber (21), a second probe for performing a composite subtraction on the counts caused by the environmental background, and a third probe for measuring the beta ray activity using a current integration method; A shielding plate for shielding beta rays in the radioactive inert gas is provided at the bottom of the second probe; The second detection component (23) comprises a first detection head for collecting the energy spectrum of Xe-133 in the sampling chamber (21) and measuring the corresponding activity concentration value, and a second detection head for avoiding counting interference caused by environmental background; An attenuation layer is provided at the bottom of the first detection head; A barrier layer is provided between the second detection head, the first detection head and the sampling chamber (21); Both the first detection head and the second detection head are provided with a radioactive source inspection tray; The first probe, the second probe and the third probe are all β probes; The first detection head and the second detection head are both gamma probes made of sodium iodide crystals.

2. The off-line leak test equipment detector system according to claim 1, characterized in that: The first probe and the second probe work together to measure the activity concentration values of Kr-85 and Xe-133 in the range of 3.7E+03Bq / m³ to 3.7E+09Bq / m³; The third probe is used to measure the activity concentration values of Kr-85 and Xe-133 within the range of 3.7E+07Bq / m³ to 3.7E+12Bq / m³; The first detection head and the second detection head work together to measure the activity concentration value of Xe-133 within the range of 3.7E+04Bq / m³~3.7E+010Bq / m³.

3. The off-line leak test equipment detector system according to claim 1, characterized in that: The gas detection device (2) further comprises a positioning frame (24), a carbon fiber layer (25) provided in the positioning frame (24) for reinforcing the positioning frame (24), a sealing ring (26) provided on the sampling chamber (21), and a processing circuit (27) provided on the positioning frame (24).

4. The off-line leak test equipment detector system according to claim 1, characterized in that: The shielding body (1) comprises a plurality of shielding block units (11), and the plurality of shielding block units (11) are connected together by fasteners; The shielding body (1) is also provided with a hanging ring (12).

5. The off-line leak test equipment detector system according to claim 4, characterized in that: It also includes a transport trolley (3) for carrying the shielding body (1); A shock-absorbing pad (31) is provided between the shielding body (1) and the transport trolley (3).

6. The off-line leak test equipment detector system according to claim 1, characterized in that: It also includes a ventilation circuit (4), wherein the ventilation circuit (4) includes an air inlet (41) connected to the sampling chamber (21) and an air outlet (42) connected to the sampling chamber (21); A filter (43) is provided between the air inlet (41) and the sampling chamber (21); A sampling pump (44) is provided between the gas outlet (42) and the sampling chamber (21).

7. The off-line leak test equipment detector system according to claim 1, characterized in that: It also includes an electrical box (5) connected to the gas detection device (2) and a host computer (6) connected to the electrical box (5).

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