An online radiation total dose detection method based on fiber microbend loss

Abstract

The application provides an online radiation total dose detection method based on fiber micro-bending loss, which comprises the following steps: firstly, placing a reaction cavity in a detection device at a detection position; a transmission window is arranged on the reaction cavity, and a polyethylene detection material is arranged in the reaction cavity; secondly, arranging the transmission window to face a radiation source; an elastic film is arranged on the reaction cavity, so that the inside of the reaction cavity is a sealed environment; then, acquiring a power value at a current time detected by a fiber micro-bending sensor in the detection device; one end of the fiber in the fiber micro-bending sensor is connected to a light source, and the other end is connected to an optical power meter; the fiber is arranged directly above the elastic film; finally, determining the radiation total dose at the current time according to the power value at the current time. The application is based on the principle of fiber micro-bending loss, and the radiation total dose received by the detection material is calculated by monitoring the power change of the fiber in real time, so that the online detection of the radiation total dose of a target environment is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radiation detection technology, and particularly relates to an online radiation total dose detection method based on optical fiber micro-bending loss. BACKGROUND

[0002] With the gradual deepening of radiation research, radiation technology has been widely applied in medical treatment, industry, agriculture and other fields. However, due to the difference of application scenes, the radiation dose required by the corresponding radiation is different, which leads to the radiation dose becoming an important factor that needs to be accurately controlled, otherwise problems such as the radiation dose being too low to produce the required radiation effect and the radiation dose being too high to damage the material may occur.

[0003] At present, in the existing radiation dose detection device, most of the radiation hydrogen release principle is applied, that is, by measuring the total amount of hydrogen generated by the cross-linking reaction of the detection material after receiving the radiation, the total dose of the radiation received by the detection material is determined. However, the detection device designed based on the radiation hydrogen release principle belongs to offline measurement, and it is difficult to realize the real-time detection demand with high precision, and it is not convenient for distributed detection. Therefore, it is necessary to develop an online radiation total dose detection method to overcome the above-mentioned shortcomings. SUMMARY

[0004] In view of the above problems, the embodiments of the present application provide an online radiation total dose detection method based on optical fiber micro-bending loss, so as to overcome the above problems or at least partially solve the above problems.

[0005] The embodiments of the present application provide an online radiation total dose detection method based on optical fiber micro-bending loss, comprising:

[0006] An online radiation total dose detection method based on optical fiber micro-bending loss, characterized in that the method comprises:

[0007] Placing a reaction cavity in a detection device at a to-be-detected position; the detection device comprises the reaction cavity, an optical fiber micro-bending sensor; a transmission window is arranged on the reaction cavity, and a polyethylene detection material is arranged in the reaction cavity;

[0008] The transmission window is arranged to face the direction of a radiation source; an elastic film is arranged on the reaction cavity, so that the inside of the reaction cavity is a sealed environment;

[0009] Obtaining a power value of the current time detected by the optical fiber micro-bending sensor; wherein the optical fiber micro-bending sensor comprises an optical fiber, a light source and an optical power meter, one end of the optical fiber is connected to the light source, one end of the optical fiber is connected to the optical power meter, and the optical fiber is arranged directly above the elastic film;

[0010] According to the power value of the current time, the total radiation dose of the current time is determined.

[0011] Optionally, the elastic film is provided with a cylinder, an optical fiber fixing sheet is arranged above the elastic film, the optical fiber fixing sheet is provided with a circular hole in the center, and an optical fiber slot is arranged in the optical fiber fixing sheet.

[0012] The power value of the current time detected by the optical fiber micro-bending sensor is obtained, including:

[0013] The detection material is irradiated to generate gas, the pressure in the reaction cavity increases, the elastic film deforms, the cylinder is lifted through the circular hole, the optical fiber is also lifted, and the optical fiber is micro-bent and deformed.

[0014] The power value of the current time detected by the optical fiber micro-bending sensor is obtained, including:

[0015] Optionally, the method further comprises:

[0016] The pressure in the reaction cavity at the current time is obtained; the detection device further comprises a pressure detection probe connected with the reaction cavity to detect the pressure in the reaction cavity in real time.

[0017] Optionally, the pressure detection probe comprises a gland, a pressure cavity, a nuclear-grade graphite gasket, an adapter component, and a pressure detection component; the outer layer of the pressure detection component is a metal shielding layer to isolate the internal detection component from the radiation environment.

[0018] Before placing the reaction cavity in the detection device at a to-be-detected position, the method comprises:

[0019] The pressure cavity is tightly connected with the reaction cavity through the gland and the nuclear-grade graphite gasket.

[0020] The pressure detection component is connected with the pressure cavity through the adapter component.

[0021] Optionally, the method further comprises:

[0022] The pressure value of the reaction cavity before detection is obtained.

[0023] In a case where the pressure value of the reaction cavity before detection exceeds a preset range, the detection is stopped, and the detection device is checked.

[0024] Optionally, the reaction cavity is divided into an irradiation reaction cavity and an elastic film reaction cavity, the irradiation reaction cavity is provided with an air pipe, and the elastic film reaction cavity is provided with a socket.

[0025] Before placing the reaction cavity in the detection device in a position to be detected, further comprising:

[0026] Connecting the gas tube with the socket to tightly connect the irradiation reaction cavity and the elastic film reaction cavity.

[0027] Optionally, the method further comprises:

[0028] In the case that the total radiation dose at the current time reaches a preset threshold, the computer outputs an alarm signal.

[0029] Optionally, according to the power value at the current time, the total radiation dose at the current time is determined, comprising:

[0030] According to the power value at the current time, the bending deformation degree of the optical fiber is determined.

[0031] According to the bending deformation degree of the optical fiber, the deformation degree of the elastic film is determined.

[0032] According to the deformation degree of the elastic film, the internal pressure value of the reaction cavity is determined.

[0033] According to the internal pressure value of the reaction cavity, the total radiation dose at the current time is calculated.

[0034] Optionally, further comprising:

[0035] Determining the difference between the pressure detected by the pressure detection probe in the reaction cavity at the current time and the internal pressure value of the reaction cavity calculated by the computer;

[0036] In the case that the difference exceeds a preset error threshold, an error detection signal is output.

[0037] Optionally, before placing the reaction cavity in the detection device in a position to be detected, further comprising:

[0038] According to the required detection accuracy, the thickness of the elastic film is determined.

[0039] The embodiment of the present application provides a kind of online radiation total dose detection method based on optical fiber microbend loss, the method comprises: first, the reaction cavity in detection device is placed in the position to be detected;Reaction cavity is provided with transmission window, and polyethylene detection material is arranged in reaction cavity;Second, the transmission window is set to face the direction of radiation source;Reaction cavity is provided with elastic film, so that the inside of reaction cavity is sealed environment;Then, the power value of current time detected by optical fiber microbend sensor in detection device is acquired;The optical fiber of the optical fiber microbend sensor is connected with light source at one end, and optical power meter is connected at one end, and the optical fiber is arranged directly above the elastic film;Finally, according to the power value of current time, the radiation total dose of current time is determined.The present application utilizes the characteristics that polyethylene generates gas after being radiated, so that the pressure in the reaction cavity increases, and then the elastic film is deformed, the optical fiber is microbent and lost, the radiation total dose received by the device is calculated by monitoring the power change of optical fiber in real time, and the online detection of the radiation total dose of target environment is realized.

[0040] The specific beneficial effects of the present application are as follows:

[0041] 1) online monitoring is realized.The embodiment of the present application utilizes the characteristics that detection material generates gas after being radiated, so that the pressure in the reaction cavity increases, and then the elastic film is deformed, the optical fiber is microbent and lost, the radiation total dose of the position to be measured is calculated by monitoring the power change of optical fiber in real time, and the online monitoring of the radiation total dose is realized.

[0042] 2) detection is accurate.The embodiment of the present application utilizes the principle of optical fiber microbend loss, utilizes the corresponding relationship function that optical power is reduced due to the deformation of optical fiber microbend, so as to utilize power loss to obtain radiation total dose, and thus, by accurately measuring the power loss value, high-precision radiation total dose calculation can be realized.

[0043] 3) low cost.The detection method of the embodiment of the present application has simple structure of detection device, low damage to each component, and can realize reuse of detection device by replacing detection material in reaction cavity, prolong the service life of the device, and reduce detection cost. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating labor intensity.

[0045] Figure 1 It is a step flow chart of the online radiation total dose detection method based on optical fiber microbend loss provided by the embodiment of the present application.

[0046] Figure 2 is a structural schematic diagram of a detection device provided by an embodiment of the present application;

[0047] Figure 3 is a structural schematic diagram of a flange-fixed transmission window provided by an embodiment of the present application;

[0048] Figure 4 is a structural schematic diagram of an elastic film provided by an embodiment of the present application;

[0049] Figure 5 is a structural schematic diagram of an optical fiber fixing plate provided by an embodiment of the present application;

[0050] Figure 6 is a structural schematic diagram of a pressure detection probe provided by an embodiment of the present application;

[0051] Figure 7 is a schematic diagram of the change relationship of variables ω, h and R0 provided by an embodiment of the present application;

[0052] BRIEF DESCRIPTION OF DRAWINGS: 1-reaction cavity, 2-polyethylene detection material, 3-transmission window, 4-elastic film, 5-optical fiber, 6-light source, 7-optical power meter, 8-computer. DETAILED DESCRIPTION

[0053] Exemplary embodiments of the present application will be described in greater detail below with reference to the accompanying drawings. Although exemplary embodiments of the present application are shown in the drawings, it is understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present application can be more thoroughly understood, and the scope of the present application can be accurately conveyed to those skilled in the art.

[0054] An online total radiation dose detection method based on optical fiber micro-bending loss is provided by an embodiment of the present application, with reference to Figure 1 , Figure 1 A step flowchart of the online total radiation dose detection method based on optical fiber micro-bending loss provided by an embodiment of the present application is shown in Figure 1 , and the method comprises:

[0055] In step S101, the reaction cavity in the detection device is placed at a detection position; the detection device comprises the reaction cavity and an optical fiber micro-bending sensor; the reaction cavity is provided with a transmission window, and the reaction cavity is provided with polyethylene detection material;

[0056] Everything in nature, as long as the temperature is above absolute zero, will be constantly transmitting heat to the outside in the form of electromagnetic waves and particles, and this way of transmitting energy is radiation. Generally, radiation can be divided into non-ionizing radiation and ionizing radiation. Non-ionizing radiation includes light, microwaves, ultrasonic waves, radio waves, etc. The energy of this kind of radiation is not high, and it generally does not harm the human body. Ionizing radiation includes alpha rays, beta rays, gamma rays, neutrons and X-rays, etc. The energy of this kind of radiation is high, and it can directly or indirectly ionize or excite matter, causing damage to materials and biological cells. The online radiation total dose detection method proposed in this embodiment is mainly designed for ionizing radiation.

[0057] In this embodiment, on the one hand, the reaction cavity in the detection device needs to have the function of isolating radiation, so that the radiation in the external environment can only enter the reaction cavity from the transmission window. In this embodiment, reference is made to the metal materials commonly used in aerospace equipment and nuclear power plant equipment. Among them, aluminum and aluminum alloy, magnesium alloy, zirconium alloy, austenitic stainless steel, and high-density pyrolytic carbon materials can be used to resist radiation high-energy particles from other directions. On the other hand, since the polyethylene detection material in the reaction cavity produces hydrogen gas by radiation, considering that the amount of hydrogen gas diffusing into aluminum is relatively low, this embodiment selects aluminum alloy as the material for making the reaction cavity, so that the data measured is more accurate and reliable.

[0058] In this embodiment, the detection material is polyethylene. In this embodiment, polyethylene is selected as the detection material, mainly using the principle of radiation-induced hydrogen release of polyethylene. This is because after the polymer is irradiated, cross-linking or degradation reactions occur, and in this process, part of the cross-linking or degradation reaction of the polymer produces gas, and the amount of gas generation increases with the depth of the reaction. Among them, the yield of polyethylene and polymethyl acrylate is relatively high, but polymethyl acrylate is liquid at room temperature and is easy to gasify by heat, which is not easy to operate and replace in actual application. Therefore, this embodiment selects polyethylene as the detection material. The melting point of polyethylene is 140°C, and the demarcation point is 300°C. Its physical and chemical properties are relatively stable in a normal temperature environment, so the data obtained by detection is more reliable. Specifically, when polyethylene is irradiated, cross-linking reaction occurs, and a large amount of gas is generated during the cross-linking reaction, most of which is hydrogen, so it is called radiation-induced hydrogen release principle. Within the range of -200°C to 100°C, the amount of gas generated by the cross-linking reaction of polyethylene is proportional to the absorbed radiation dose, and has no significant correlation with the type of high-energy radiation and the dose rate, and has high stability.

[0059] In this embodiment, reference is made to Figure 2 , Figure 2 A structural schematic diagram of a detection device is shown, as Figure 2As shown, a groove is arranged inside the reaction cavity 1, and the detection material 2 can be fixed in the groove. An opening is arranged above the groove, and the transmission window 3 is covered and fixed at the opening by a flange structure. In this embodiment, the transmission window is arranged in the reaction cavity, so that the radiation can pass through the transmission window into the reaction cavity and then into the detection material. The gas generated by the detection material under the radiation mainly flows in the direction indicated by the arrow in Figure 2 . The transmission window can be arranged directly above the detection material. Specifically, an opening is arranged directly above the detection material, the diameter of the transmission window is slightly larger than the diameter of the opening, the transmission window completely covers the opening, and the flange device is used to fix the transmission window at the opening. In this way, the radiation can pass through the transmission window into the detection material.

[0060] In this embodiment, the flange structure at least includes a graphite gasket and six hexagonal head bolts. Since the transmission window directly faces the radiation source, the cumulative radiation dose is large. The Viton, fluorine rubber and other gaskets commonly used in the flange structure will change in structure under high radiation dose, which reduces the sealing performance of the flange and produces impurity gas. If a metal spring gasket is used, the roughness requirement of the metal surface is at least not greater than 0.4 μm, which leads to a greater difficulty in processing the gasket. If a metal spring gasket with roughness that does not meet the above requirement is used, the sealing effect of the metal surface is poor, and in the case where the material of the transmission window is quartz glass, the high-pressure gun required by the extremely high sealing load makes the glass transmission window extremely easy to break during the fixing process. Therefore, the graphite gasket with good sealing performance is selected in this embodiment, which effectively avoids the influence of high radiation dose on the gasket and achieves good sealing effect.

[0061] In this embodiment, since the graphite seal requires a certain load to achieve good sealing effect, the number and strength grade of the flange bolts need to be calculated according to the graphite sealing load. Specifically, the load formula of the nuclear-grade graphite seal is F1=(R1 2 -r1 2 )π×P1, wherein P1=60Mpa, R1 is the outer diameter, and r1 is the inner diameter. The size of the graphite gasket is 30mm×38mm×3.5mm (inner diameter / outer diameter / height). According to the maximum range of the theoretical pressure corresponding to 100kGy, P2=14.65kPa, and the window radius of the transmission window is r2=10mm, the residual maximum preload needs to be considered, and the axial load of the bolt is calculated as F=F1+πr2 2 P2. The calculation formula of the bolt diameter is:

[0062]

[0063] Where n is the number of bolts, and [σ] is the safe value of the yield strength σ corresponding to the bolt's material grade, i.e., relative to the safety factor S, [σ] = σ / s. Following the principle of minimizing mass and simplifying design, the relationship between bolt grade, quantity, and diameter should be weighed. Here, we take the safety factor S = 2.5, the number of bolts n = 6, the bolt grade 10.9, and the yield strength σ = 900 MPa obtained from the table. Therefore, according to the above formula, the bolt diameter d ≥ 3.96 mm, and here we take d = 4.0 mm. Based on the above analysis, this embodiment selects 6 M4 hexagonal head bolts with a strength grade of 10.9.

[0064] Reference Figure 3 , Figure 3 A schematic diagram of a flange-fixed transmission window is shown, as follows. Figure 3 As shown, the transmission window is a circular thin sheet. The flange is clamped on the upper and lower sides of the transmission window by two graphite gaskets respectively, and it is fixed to the reaction chamber by six hexagonal head bolts. This achieves a fixed connection between the transmission window and the reaction chamber, avoiding the possibility of radiation leakage from the connection gap.

[0065] Step S102: Set the transmission window to face the radiation source; an elastic film is provided on the reaction chamber to make the inside of the reaction chamber a sealed environment;

[0066] In this embodiment, by setting the transmission window to face the radiation source, when radiation enters the polyethylene detection material through the transmission window, the detection material undergoes cross-linking due to radiation, generating gas and causing a pressure change in the reaction chamber. An elastic membrane is also provided on the reaction chamber to make the inside of the reaction chamber a sealed environment. When the pressure in the reaction chamber changes, the elastic membrane deforms simultaneously.

[0067] In one embodiment, the transmission window is made of quartz glass with a thickness of 1.0 mm, or the transmission window is made of polyetheretherketone (PEEK) with a thickness of 2.0 mm. For the transmission window, either quartz glass or PEEK can be chosen to ensure that the window can transmit a large number of electrons and protons, without significant changes to the mechanical structure due to radiation, and without generating impurity gases that could affect detection. PEEK, as a plastic material, has excellent radiation resistance; its tensile strength, flexural strength, flexural modulus, and density remain almost unchanged before and after 75 kGy gamma radiation. Therefore, both quartz glass and PEEK can be used as materials for the transmission window.

[0068] The thickness of the transmission window should be selected considering both mechanical properties and ion penetration performance. The specific calculation process is as follows:

[0069] When the transmission window is made of quartz glass, first, for the quartz disc using edge support, the disc fracture formula can be obtained as follows:

[0070]

[0071] Where t is the thickness of the quartz disc (mm), r is the radius of the suspended part of the quartz disc (mm), which is 15 mm in this case, p0 is the ultimate load of the disc (Pa), S max is the maximum stress (Pa) that the quartz glass can withstand, i.e., the fracture strength. Since a safety factor is usually required for the maximum stress, according to the relevant data on the relationship between the safety factor of glass strength and failure probability, a safety factor of 3.0 can meet the requirements, i.e., Therefore, considering a certain safety factor, for the ultimate pressure p0 = 70 kPa, the minimum thickness t glass of the glass is 0.070 mm. To avoid the case of excessive local pressure due to insufficient flatness during processing, in this embodiment, when the transmission window is made of quartz glass, the thickness is 1.0 mm; similarly, for polyether ether ketone, the Young's modulus is about half of that of quartz glass, and the calculation can obtain the minimum thickness t PEEK = 0.098 mm, and when the transmission window is made of polyether ether ketone, the thickness is 2.0 mm.

[0072] In this embodiment, as shown in Figure 2 , holes are provided on the reaction cavity, and the elastic membrane 4 is covered and fixed at the holes, so that the inside of the reaction cavity is a sealed environment; in this embodiment, after the radiation passes through the transmission window and enters the detection material, the detection material receives the radiation, undergoes crosslinking reaction, and generates gas. Holes are also provided on the reaction cavity, and the elastic membrane is covered and fixed at the holes, so that the inside of the reaction cavity is a sealed environment and does not flow with the outside environment. Thus, in the reaction cavity, when the gas increases and the pressure increases, the elastic membrane deforms and expands outward. Correspondingly, the more total dose of radiation the detection material receives, the more gas in the reaction cavity, and the more serious the deformation of the elastic membrane.

[0073] In step S103, a power value at a current time detected by the optical fiber micro-bend sensor is obtained; wherein the optical fiber micro-bend sensor includes an optical fiber, a light source and an optical power meter, one end of the optical fiber is connected to the light source, and one end is connected to the optical power meter, and the optical fiber is arranged directly above the elastic membrane;

[0074] In this embodiment, the fiber optic microbending sensor is used to determine the power value of the fiber optic cable affected by deformation. The fiber optic microbending sensor includes an optical fiber, a light source, and an optical power meter. The optical fiber is positioned directly above the elastic film. When the elastic film deforms, the optical fiber bends accordingly, thereby changing its power value. One end of the optical fiber is connected to the light source, and the other end is connected to the optical power meter. Furthermore, the optical power meter can be connected to a computer via a cable, thereby transmitting the detected power value to the computer.

[0075] In this embodiment, as Figure 2 As shown, the fiber optic micro-bending sensor includes an optical fiber 5, a light source 6, and an optical power meter 7. One end of the optical fiber is connected to the light source, and the other end is connected to the optical power meter. The optical fiber is located directly above the elastic film. In this embodiment, the optical fiber is a single, complete optical fiber. One end of the optical fiber is connected to the optical power meter, and the other end is connected to the light source. The light source provides a stable light source input, and the optical power meter can detect the optical power value at the output end of the optical fiber in real time. The light source and optical power meter can be housed in a shielded box. The metal material of the shielded box isolates external radiation, thus protecting the light source and optical power meter from radiation damage. Because the optical fiber is located directly above the elastic film, during radiation dose detection, the detection material generates gas upon radiation, increasing the pressure within the reaction chamber and causing elastic deformation of the elastic film. In this embodiment, the optical fiber is positioned directly above the elastic film, so that when the elastic film deforms, it exerts upward pressure on the optical fiber, causing the optical fiber to bend slightly, resulting in micro-bending deformation. It is important to understand that when an optical fiber is subjected to uneven stress, the fiber axis undergoes minute and irregular bending, altering the light propagation path. This causes light to penetrate from the core into the cladding, and may even penetrate through the cladding outwards. The transmission mode changes to a radiation mode, resulting in energy loss and ultimately a reduction in optical power. Therefore, in this embodiment, the greater the deformation of the elastic film and the greater the degree of fiber bending, the greater the optical power loss.

[0076] Step S104: Determine the total radiation dose at the current moment based on the power value at the current moment.

[0077] In this embodiment, as Figure 2As shown, the optical power meter 7 is connected to the computer 8 through a cable, so as to send the detected optical power value to the computer, and the computer determines the total dose of radiation at the current time according to the change of the received optical power value. In an embodiment, the cable is connected to the computer through a metal pipe. By arranging the metal pipe, the metal pipe is connected to the optical power meter and the computer, and the cable passes through the metal pipe to complete signal transmission, so as to avoid that the cable is exposed to the radiation environment and causes radiation damage. In this process, the optical power meter can send the detected power value to the computer at a certain time interval, for example, the power value at the current time is sent to the computer every 1s, 2s or 5s, which is not limited in this embodiment. Moreover, a linear function between the optical power loss value and the total dose of radiation can be stored in the computer in advance, and the power loss of the optical fiber is taken as an input value, so as to calculate the output total dose of radiation.

[0078] In an embodiment, the total dose of radiation at the current time is determined according to the power value at the current time, including:

[0079] The bending deformation degree of the optical fiber is determined according to the power value at the current time.

[0080] The deformation degree of the elastic film is determined according to the bending deformation degree of the optical fiber.

[0081] The internal pressure value of the reaction cavity is determined according to the deformation degree of the elastic film.

[0082] The total dose of radiation at the current time is calculated according to the internal pressure value of the reaction cavity.

[0083] In this embodiment, after the computer obtains the current power value of the optical fiber detected by the optical power meter, the degree of loss of the optical fiber power, that is, the reduction of the optical power, is calculated, and the bending deformation degree of the optical fiber, or the bending angle of the optical fiber, is calculated. The greater the reduction of the optical power, the greater the bending angle of the optical fiber. Then, the deformation degree of the elastic film is calculated according to the bending deformation degree of the optical fiber, and the internal pressure value of the reaction cavity is obtained. That is, the more obvious the bending deformation of the optical fiber, the more obvious the deformation of the elastic film, and the greater the internal pressure of the reaction cavity. Finally, the amount of the gas increased in the reaction cavity is calculated according to the internal pressure value of the reaction cavity, and the total dose of radiation received by the detection material at the current time is obtained.

[0084] The embodiment places the reaction cavity in the detection device at a position to be detected, sets the transmission window of the reaction cavity to face the direction of the radiation source, and when the radiation passes through the transmission window into the detection material in the reaction cavity, the detection material generates gas, causing the pressure in the reaction cavity to change and the elastic membrane on the reaction cavity to deform; the fiber micro-bend sensor determines the current power value and sends it to the computer; when the elastic membrane deforms, the optical fiber in the fiber micro-bend sensor also deforms; the computer calculates the total radiation dose at the current time according to the current power value of the optical fiber. The embodiment uses the characteristic that the detection material generates gas after being radiated, increases the pressure in the reaction cavity, and further causes the elastic membrane to deform and the optical fiber to have micro-bend loss; by monitoring the power change of the optical fiber in real time, the total radiation dose at the position to be detected is calculated. Thus, the total radiation dose is monitored online. By using the principle of optical fiber micro-bend loss and the corresponding relationship function that the optical power decreases due to the deformation of the optical fiber, the total radiation dose is obtained by backstepping from the power loss. Thus, by accurately measuring the power loss value, the total radiation dose can be calculated with high precision. In addition, the detection device used in the detection method of the embodiment has a simple structure and causes low damage to components, the detection device can be reused by replacing the detection material in the reaction cavity, the service life of the device is prolonged, and the detection cost is reduced.

[0085] In an embodiment, the method further comprises:

[0086] In the case where the total radiation dose at the current time reaches a preset threshold, the computer outputs an alarm signal.

[0087] In the embodiment, a threshold can be set in advance, and when the output total radiation dose exceeds the preset threshold, the computer sends an alarm signal to the relevant staff, indicating that the total radiation dose received at the position has exceeded the preset threshold, so that the staff can close the radiation or perform other related operations according to the alarm signal, thereby achieving real-time monitoring and early warning.

[0088] In an embodiment, a cylinder is arranged at the center of the elastic membrane, an optical fiber fixing sheet is arranged above the elastic membrane, a circular hole is arranged at the center of the optical fiber fixing sheet, an optical fiber groove is arranged in the optical fiber fixing sheet, and the optical fiber is fixed in the optical fiber groove and passes through the circular hole.

[0089] The power value at the current time detected by the optical fiber micro-bend sensor comprises:

[0090] The detection material is radiated to generate gas, the pressure in the reaction cavity increases, the elastic membrane deforms, the cylinder is lifted through the circular hole, the optical fiber is also lifted, and the optical fiber deforms.

[0091] The optical power meter detects the current power value of the optical fiber.

[0092] In the embodiment, referring to Figure 4 , Figure 4 A schematic diagram of the structure of the elastic film is shown, as Figure 4 shown, a hole is arranged on the reaction cavity, and the elastic film covers and is fixed at the hole, so that the inside of the reaction cavity is a sealed environment. A cylinder is arranged at the center of the elastic film. When the pressure inside the reaction cavity increases and the elastic film deforms, the cylinder will be pushed up. An optical fiber fixing sheet is arranged above the elastic film. The center of the optical fiber fixing sheet is provided with a circular hole, and the cylinder vertically corresponds to the circular hole. Thus, when the cylinder is pushed up, it can pass through the circular hole. Referring to Figure 5 , Figure 5 A schematic diagram of the structure of the optical fiber fixing sheet is shown. The center of the optical fiber fixing sheet is provided with a circular hole, and an optical fiber groove is arranged. The optical fiber groove is a groove transversely passing through the circular hole, and the optical fiber can be fixed in the optical fiber groove and pass through the circular hole. The embodiment realizes adding a cylinder at the center of the film to make a micro-bending mechanism. The cylinder passes through the through hole in which the optical fiber is fixed to simulate micro-bending teeth, so that the loss function can be solved by using the model of the tooth-shaped optical fiber micro-bending theory.

[0093] Thus, in the process of radiation detection, the detection material is subjected to radiation, gas is generated, the pressure in the reaction cavity increases, the elastic film deforms, the cylinder of the elastic film is pushed up, and when it passes through the circular hole, the optical fiber will be pushed up at the same time, so that the optical fiber deforms. The optical power meter can determine the power loss of the optical fiber caused by the micro-bending deformation by detecting the power value of the optical fiber at the current time.

[0094] In an embodiment, the method further comprises:

[0095] The pressure in the reaction cavity at the current time is obtained. The detection device further comprises a pressure detection probe connected with the reaction cavity, which detects the pressure in the reaction cavity in real time.

[0096] In the embodiment, the pressure in the reaction cavity can be detected in real time by connecting the pressure detection probe with the reaction cavity, so that the pressure in the reaction cavity at the current time can be directly obtained, and auxiliary calculation and judgment can be performed according to the obtained pressure.

[0097] In an embodiment, the method further comprises:

[0098] determining a difference between the pressure detected by the pressure detection probe and the internal pressure of the reaction chamber calculated by the computer;

[0099] outputting a detection error signal if the difference exceeds a preset error threshold.

[0100] In this embodiment, after the computer calculates the loss of optical power, it calculates the micro-bending angle of the optical fiber, and reversely calculates the deformation degree of the elastic film, so as to calculate the pressure in the reaction chamber, and then deduce the amount of gas generated by the polyethylene detection material, and finally calculate the total dose of radiation received by the detection material according to the amount of gas. In order to further ensure the accuracy of the final calculation result, this embodiment can also obtain the pressure in the reaction chamber at the current time through the pressure detection probe while detecting the radiation dose. Thus, the pressure value at the current time can be used for auxiliary calculation. For example, the pressure value reversely calculated according to the micro-bending angle of the optical fiber is compared with the pressure value directly tested by the pressure detection probe. If the error between the two does not exceed the preset error threshold, the final calculated total dose of radiation is output. If the error between the two pressure values exceeds the preset error threshold, a detection error signal is output, prompting the relevant staff to check and calibrate the detection device.

[0101] In one embodiment, the pressure detection probe comprises a gland, a pressure chamber, a nuclear-grade graphite gasket, an adapter component, and a pressure detection component. The outer layer of the pressure detection component is a metal shielding layer, which separates the internal detection component from the radiation environment.

[0102] Before placing the reaction chamber in the detection device in the to-be-detected position, the method comprises:

[0103] The pressure chamber is tightly connected to the reaction chamber through the gland and the nuclear-grade graphite gasket.

[0104] The pressure detection component is connected to the pressure chamber through the adapter component.

[0105] In this embodiment, with reference to Figure 6 , Figure 6 a structure diagram of a pressure detection probe is shown, as Figure 6As shown, the pressure detection probe includes a gland, a pressure cavity, a nuclear-grade graphite gasket, an adapter component, and a pressure detection component. Before placing the detection device in the position to be detected, the pressure detection probe needs to be assembled on the reaction cavity. Specifically, the pressure cavity is connected with the reaction cavity through the gland and the nuclear-grade graphite gasket. In this embodiment, in order to connect the pressure detection probe with the reaction cavity, a corresponding opening needs to be provided on the reaction cavity. It should be noted that the size of the opening needs to be matched with the size of the interface of the pressure cavity, so as to avoid gaps when the two are connected. Moreover, the pressure detection probe is connected with the computer through a cable, so as to send the detected pressure value to the computer. The pressure detection component is connected with the pressure cavity through the adapter component. The outer layer of the pressure detection component is a metal shielding layer, which plays a role of protecting the internal detection component and isolating it from the radiation in the external environment to avoid radiation damage.

[0106] In an embodiment, the method further comprises:

[0107] obtaining the pressure value of the reaction cavity before detection;

[0108] if the pressure value of the reaction cavity before detection is out of the preset range, stopping the detection and checking the detection device.

[0109] In this embodiment, after the pressure detection probe is connected with the reaction cavity, the pressure value inside the reaction cavity is obtained before the radiation dose detection. In a normal environment, the pressure value of the reaction cavity should be within the normal pressure range. In this embodiment, a preset range can be set in advance. If the pressure value is lower than or higher than the preset range, it indicates that the reaction cavity has a problem and cannot be directly used for radiation dose detection.

[0110] In an embodiment, the reaction cavity is divided into an irradiation reaction cavity and an elastic film reaction cavity. The irradiation reaction cavity is provided with an air pipe, and the elastic film reaction cavity is provided with a socket.

[0111] Before placing the reaction cavity in the detection device in the position to be detected, the method further comprises:

[0112] connecting the air pipe with the socket to tightly connect the irradiation reaction cavity and the elastic film reaction cavity.

[0113] In the embodiment, the smaller the volume of the detection device is, the more convenient the detection in the environment is, and the more extensive the applicable detection environment is. In order to minimize the volume of the detection device as much as possible, the reaction cavity can be arranged as an irradiation reaction cavity and an elastic film reaction cavity, and the irradiation reaction cavity and the elastic film reaction cavity are connected through the air pipe and the port between the detection device is placed in the position to be detected. Thus, the transmission window is arranged on the irradiation reaction cavity, the detection material is arranged in the irradiation reaction cavity, the polyethylene detection material in the irradiation reaction cavity generates gas, which is transmitted to the elastic film reaction cavity through the connected air pipe and the port, and then the elastic film arranged on the elastic film reaction cavity is elastically deformed, so that the optical fiber above it is correspondingly micro-bent. The length of the air pipe can be arranged according to the actual situation, and in the embodiment, it is not limited.

[0114] It is considered that when the air pipe and the port cooperate with each other, due to the cooperation precision between the components, a gap is easily generated. In the embodiment, in order to solve the above problem, the air pipe is arranged as a stepped structure, as shown in Figure 3 , so that the air pipe can be just clamped into the port to form a tight connection channel, and the gas in the reaction cavity cannot leak to the outside environment, and the radiation into the reaction cavity is also avoided. In addition, a sleeve can also be arranged at the connection position to cover a gap of the connection, so as to further improve the air tightness of the reaction cavity.

[0115] In one embodiment, before the reaction cavity in the detection device is placed in the position to be detected, the method further comprises:

[0116] According to the required detection accuracy, the thickness of the elastic film is determined.

[0117] For the elastic film, on the one hand, it needs to have a certain elastic deformation ability, and can be elastically deformed sensitively when the pressure in the reaction cavity changes; on the other hand, since the detection device is arranged in a radiation environment, the elastic film will be affected by a certain radiation to a certain extent. In order to avoid the problems that the elastic film changes in quality and generates gas after receiving the radiation, the elastic film also needs to have a certain anti-radiation ability. In the embodiment, polyether ether ketone is selected as the material of the elastic film, so as to ensure the anti-radiation ability and elasticity of the elastic film.

[0118] In the embodiment, the thickness of the elastic film can be determined according to the required detection accuracy. Specifically, the thickness and radius of the elastic film are the main parameters in the design and production of the device, and the values thereof affect the range and resolution of the detection device. Under the condition of small deflection, according to the principle of elasticity, the deformation of the elastic film after being subjected to pressure is as follows:

[0119]

[0120] Wherein: ω is the deflection of the sensitive diaphragm; p is the pressure borne by the sensitive diaphragm; μ is the Poisson's ratio; E is the Young's modulus of silicon; h is the thickness of the sensitive diaphragm; R0 is the radius of the diaphragm; and r is the radius of the diaphragm at any position. Taking the pressure p = 1 kPa, the reference Figure 7 , Figure 7 A schematic diagram showing the change relationship of the variables ω, h and R0 is shown in FIG. 2. As shown in FIG. 2, the corresponding sensitivity expression is: Figure 7

[0121]

[0122] It is not difficult to conclude that the larger the radius R is, the smaller the thickness h is, and the higher the sensitivity is; that is, when a higher detection accuracy is required, a thinner elastic diaphragm is selected, and when a lower detection accuracy is required, a thicker elastic diaphragm is selected. Through testing, it is obtained that when the thickness h < 0.6 mm and the radius R > 20 mm, the error influence of the two parameters is greater. Specifically, in order to reduce the overall volume of the detection device and comprehensively consider the processing difficulty, appropriate values should be selected under the premise of ensuring a certain sensitivity. Exemplarily, h = 0.7 mm and R = 20.0 mm can be taken.

[0123] Each of the embodiments in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same and similar parts between the embodiments can be referred to each other.

[0124] The embodiments of the present application are described with reference to flowcharts and / or block diagrams according to the methods, devices, electronic equipment and computer program products of the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing terminal equipment to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal equipment realize the functions specified in the flowcharts and / or block diagrams. Figure 1 The functions specified in one flow or multiple flows and / or blocks Figure 1 The device of the functions specified in one block or multiple blocks. Moreover, the background color in the diagrams herein does not cover any meaning, and has no limiting meaning on the devices and methods proposed herein, and can be changed to other colors at will.

[0125] Although the preferred embodiments of the embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to the embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present application.

[0126] ​Finally, it is to be understood that the phraseology or terminology such as "first" and "second" etc. used herein is merely intended to differentiate one entity or operation from another without necessarily requiring or implying any actual such relationship or order between such entities or operations. Moreover, the use of the term "comprising", "containing" or any other variant thereof is intended to cover non-exclusive inclusions, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0127] The above describes in detail the method for detecting total dose of radiation based on fiber micro-bending loss provided by the present application. The principle and implementation of the present application are described by using specific examples. The above description of the examples is only used to help understand the method of the present application and its core idea. Meanwhile, for those skilled in the art, the specific implementation and application range can be changed according to the idea of the present application. In summary, the content of the present description should not be understood as a limitation of the present application.

Claims

1. An online total dose detection method based on fiber microbend loss, characterized in that, The method comprises: Placing a reaction cavity in a detection device in a position to be detected; the detection device comprises the reaction cavity, a fiber optic micro-bend sensor; the reaction cavity is provided with a transmission window, and the reaction cavity is provided with polyethylene detection material; the transmission window is arranged to face the direction of a radiation source; the reaction cavity is provided with an elastic film, so that the inside of the reaction cavity is a sealed environment; The reaction cavity is divided into an irradiation reaction cavity and an elastic film reaction cavity, the irradiation reaction cavity is provided with an air pipe, and the elastic film reaction cavity is provided with a socket; Obtaining a power value at the current time detected by the fiber optic micro-bend sensor; wherein the fiber optic micro-bend sensor comprises an optical fiber, a light source and an optical power meter, one end of the optical fiber is connected to the light source, one end of the optical fiber is connected to the optical power meter, and the optical fiber is arranged directly above the elastic film; According to the power value at the current time, determining the total radiation dose at the current time; The center of the elastic film is provided with a cylinder, the upper part of the elastic film is provided with a fiber fixing sheet, the center of the fiber fixing sheet is provided with a circular hole, the fiber fixing sheet is provided with a fiber groove, the fiber is fixed in the fiber groove and passes through the circular hole; Obtaining a power value at the current time detected by the fiber optic micro-bend sensor, comprising: The polyethylene detection material is irradiated to generate gas, the pressure in the reaction cavity increases, the elastic film deforms, the cylinder is lifted to pass through the circular hole, the fiber is also lifted, and the fiber is deformed by micro-bending; Obtaining the power value at the current time detected by the optical power meter.

2. The method of claim 1, wherein the fiber optic microbend loss based online radiation total dose detection method is characterized by, Further comprising: Obtaining the pressure in the reaction cavity at the current time; The detection device further comprises a pressure detection probe connected with the reaction cavity to detect the pressure in the reaction cavity in real time.

3. The method of claim 2, wherein the fiber optic microbend loss is based on a change in the fiber optic microbend loss due to the radiation dose. The pressure detection probe comprises a gland, a pressure cavity, a nuclear-grade graphite gasket, an adapter component and a pressure detection component; the outer layer of the pressure detection component is a metal shielding layer to isolate the internal detection component from the radiation environment; Before placing the reaction cavity in the detection device in the position to be detected, comprising: Through the gland and the nuclear-grade graphite gasket, the pressure cavity is tightly connected with the reaction cavity; Through the adapter component, the pressure detection component is connected with the pressure cavity.

4. The method according to claim 3, wherein the fiber optic microbend loss based online radiation total dose detection method is characterized by, The method further comprises: Obtaining the pressure value of the reaction cavity before detection; In the case that the pressure value of the reaction cavity before detection exceeds a preset range, stopping detection and checking the detection device.

5. The method of claim 1, wherein the fiber optic microbend loss based online radiation total dose detection method is characterized by, Before placing the reaction cavity in the detection device in the position to be detected, further comprising: Connecting the air pipe with the socket to tightly connect the irradiation reaction cavity and the elastic film reaction cavity.

6. The method of claim 1, wherein the fiber optic microbend loss based online radiation total dose detection method is characterized by, The method further comprises: In the case that the total radiation dose at the current time reaches a preset threshold, the computer outputs an alarm signal.

7. The method according to claim 2, wherein the fiber optic microbend loss based online radiation total dose detection method is characterized by, According to the power value at the current time, determining the total radiation dose at the current time, comprising: According to the power value at the current time, determining the bending deformation degree of the optical fiber; According to the bending deformation degree of the optical fiber, the deformation degree of the elastic film is determined; According to the deformation degree of the elastic film, the internal pressure value of the reaction cavity is determined; According to the internal pressure value of the reaction cavity, the total radiation dose at the current time is calculated.

8. The method according to claim 7, wherein the fiber optic microbend loss based online radiation total dose detection method is characterized by, Further comprising: Determine the difference between the pressure detected by the pressure detection probe in the reaction cavity at the current time and the internal pressure value of the reaction cavity calculated by the computer; If the difference exceeds the preset error threshold, an error detection signal is output.

9. The method according to claim 1, wherein the fiber optic microbend loss based online radiation total dose detection method is characterized by, Before placing the reaction cavity in the detection device at the detection position, further comprising: According to the required detection accuracy, the thickness of the elastic film is determined.

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