An irradiation test stand and method of using the same

Abstract

The present application relates to a kind of irradiation experimental line mechanism, including walking part and fixed part, walking part includes experimental box, the suspension chain of experimental box top and anchor iron being arranged at the bottom of experimental box are constituted;Fixed part includes the track for the walking of suspension chain, and the limiting anchor rail that is arranged below track and cooperates with anchor iron.Implementation, the experimental box can utilize irradiation device monitoring line to carry out irradiation experiment, provide effective data for small-dose gamma irradiation processing, realize the stable balance of irradiation dose range;For the effective data obtained by experimental box, draw out isodose distribution curve diagram, the index such as the statistics equivalent maximum dose area, equivalent minimum dose area, dose non-uniformity, main control time and absorbed dose relationship, so that production line can carry out small-dose precision irradiation, avoid capacity waste.

Description

Technical Field

[0001] This invention relates to the technical field of gamma irradiation equipment, specifically to an irradiation experimental line mechanism and its usage method, and more particularly to an irradiation experimental line mechanism and its usage method for conducting irradiation dose experiments using a gamma irradiation device monitoring line. Background Technology

[0002] In industrial gamma irradiation facilities, for the purpose of video safety inspection of irradiation equipment such as cobalt-60 source racks, irradiation boxes, and conveying mechanisms within the irradiation chamber, the aim is to achieve automated video inspection of surrounding or fixed-point locations within the irradiation environment. A lightweight overhead conveyor system, referred to as a monitoring line, is typically designed and installed within the irradiation chamber. This monitoring line transports the video inspection equipment to a closed loop within the maze and fortifications between the irradiation chamber and the cargo entrance / exit to achieve this video monitoring objective. Simultaneously, during routine safety inspections or in emergency situations, the monitoring line, via the overhead conveyor, carries the video inspection equipment or other emergency facilities into the irradiation chamber for video inspection or emergency response.

[0003] This patent aims to meet the relevant clauses of GB18280 / ISO11137 standards in irradiation processing activities, particularly the experimental requirements for product irradiation dose setting and dose verification. This patent provides the irradiation environment equipment and irradiation process required to achieve these requirements, utilizing a suspended chain conveyor system on the irradiation device monitoring line and configuring a suspended experimental chamber for irradiation dose experiments. The implementation of the irradiation experimental function of this suspended chain conveyor system is referred to as the experimental line. Essentially, through a series of technical measures, the irradiation function and its usage method of the irradiation device monitoring line are developed and utilized, meeting the requirements of low-dose gamma irradiation processes such as product irradiation dose setting and dose verification, extending the process chain and irradiation dose range of the irradiation plant to meet the relevant requirements of standards such as GB18280 / ISO11137.

[0004] According to the requirements of GB 18280 / ISO11137, the required dose range for low-dose gamma irradiation, such as product irradiation dose setting and dose verification, should be controlled within ±10% of the target dose. The ratio of the required maximum dose to the required minimum dose is 1.22, which is a very narrow dose range and places extremely high demands on the implementation of the irradiation process.

[0005] Currently, to meet the requirements of low-dose precision irradiation, areas with uniform dose rates are typically selected within the irradiation trays of gamma irradiation equipment production lines. This results in low tray utilization rates. Statistics show that only 10% of the tray volume is usable to meet the low-dose precision irradiation requirements. Considering the size of the products to be processed and loading requirements, the actual utilization rate is only about 2%, meaning the entire tray is essentially wasting capacity. Furthermore, this method also places requirements on the products loaded in other trays within the irradiation chamber. The density of the loaded products needs to be controlled to achieve a uniform and approximate condition throughout the irradiation chamber, avoiding excessive density differences that could lead to uneven radiation penetration and affect the implementation of low-dose precision irradiation. In conclusion, conducting low-dose precision irradiation on a production line presents significant drawbacks, including severe capacity waste and high processing control requirements. Summary of the Invention

[0006] The purpose of this invention is to provide an improved irradiation experimental line mechanism and its usage method. By setting up an experimental box and matching limiting anchor rails, irradiation dose experiments are conducted. Through experimental data, small-dose precise irradiation is achieved, thereby improving the utilization rate of tray loading on the production line.

[0007] To achieve the above objectives, the technical solution of the present invention is: an irradiation experimental line mechanism, characterized in that: the experimental line mechanism includes a traveling part and a fixed part, the traveling part comprising an experimental box, a suspension chain disposed on the top of the experimental box and an anchor iron disposed on the bottom of the experimental box; the fixed part includes a track for the traveling of the suspension chain and a limiting anchor rail disposed below the track and cooperating with the anchor iron.

[0008] Preferably, the experimental box includes a box frame, the front of which is provided with an openable box door, and the top and bottom of the box frame are provided with connecting blocks; the anchor is composed of an anchor body and a set of anchor tips located below the body, the anchor body is made of hollow square steel, and the anchor tips have a wedge-shaped structure.

[0009] Furthermore, the limiting anchor rail is set on the sleeper plate. The limiting anchor rail is composed of a straight rail and a transition rail. The transition rail is set at both ends of the straight rail, and there is an angle of 25-45 degrees between the transition rail and the straight rail.

[0010] A method for using an irradiation experimental line mechanism is characterized by the following steps: a) setting three measurement planes on two sides and the middle of the experimental chamber, and uniformly arranging dosimeters on the three measurement planes according to a grid; b) after locking the chamber door, the experimental chamber enters the irradiation chamber via a suspension chain for fixed-point irradiation. When the irradiation processing time is completed, the experimental chamber moves to the unloading platform via the suspension chain and unloads the irradiated dosimeters; c) measuring the dosimeters, recording all measurement results, and plotting isodose distribution curves of the three measurement planes based on the measurement values ​​to obtain the maximum and minimum dose areas, maximum and minimum dose points, and dose values. Subsequent adjustments to the irradiation time and dosimeter arrangement during irradiation processing can improve the controllability and repeatability of the product irradiation dose and achieve a stable and balanced irradiation dose range.

[0011] Compared with the prior art, the technical solution of the present invention not only improves the overall technical solution, but also includes many improvements in details. Specifically, it has the following beneficial effects:

[0012] 1. The improved solution of the present invention has a suspension chain at the top of the experimental chamber and an anchor iron at the bottom. The experimental chamber can use the monitoring line of the irradiation device to carry out irradiation experiments, provide effective data for small-dose gamma irradiation processing, and achieve stable and balanced irradiation dose range.

[0013] 2. In the technical solution of the present invention, the limiting anchor rail is set on the sleeper plate. The limiting anchor rail is composed of a straight rail and a transition rail. The transition rail is set at both ends of the straight rail. By setting the limiting anchor rail, the stability of the experimental box is ensured, the loading and unloading operation is safe and reliable, the operation risk is reduced, and the accuracy of the experimental data is improved.

[0014] 3. The data obtained after the experiment of this invention can be used to plot the isodose distribution curve, and to statistically analyze indicators such as the equivalent maximum dose region, the equivalent minimum dose region, dose non-uniformity, the relationship between master control time and absorbed dose, providing a technical basis for the irradiation process design of irradiation dose experiments.

[0015] 4. The experimental line mechanism of the present invention has a simple structure and installation method. It can be set up using existing irradiation device monitoring lines. It is easy to operate during use and obtains rich and accurate data after testing. It has great commercial value and is easy to promote and utilize. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention.

[0017] Figure 2 This is a schematic diagram of the experimental box of the present invention.

[0018] Figure 3 This is a schematic diagram of the anchor structure of the present invention.

[0019] Figure 4 for Figure 3 A schematic diagram of the AA-direction structure.

[0020] Figure 5 for Figure 3 A schematic diagram of the BB-oriented structure.

[0021] Figure 6 This is a schematic diagram of the anchor rail structure of the present invention.

[0022] Figure 7 This is another structural schematic diagram of the anchor rail of the present invention.

[0023] Figure 8 This is a diagram illustrating the effect of single-sided irradiation dose range in an embodiment of the present invention.

[0024] Figure 9 This is a diagram illustrating the effect of bi-lateral irradiation dose range in an embodiment of the present invention.

[0025] Figure 10 This is a reference setup diagram of the three measuring planes in an embodiment of the present invention.

[0026] Figure 11 This is a reference setting diagram of the measuring plane on the left side of the experimental box in an embodiment of the present invention.

[0027] Figure 12 for Figure 11 A graph showing the absorbed dose values ​​at various points on the measurement plane.

[0028] Figure 13 This is a reference setting diagram of the measuring plane on the right side of the experimental box in an embodiment of the present invention.

[0029] Figure 14 for Figure 13 A graph showing the absorbed dose values ​​at various points on the measurement plane.

[0030] Figure 15 This is a reference setting diagram of the measurement plane in the middle of the experimental box in an embodiment of the present invention.

[0031] Figure 16 for Figure 15 A graph showing the absorbed dose values ​​at various points on the measurement plane.

[0032] Figure 17 This is a surface dose distribution diagram of the irradiation chamber of the gamma irradiation device of the present invention.

[0033] Figure label:

[0034] 1. Anchor iron; 2. Experiment box; 3. Limiting anchor rail;

[0035] 11 anchor iron body, 12 anchor tip;

[0036] 21 Suspension connector, 22 Box frame, 23 Box door, 24 Connecting block;

[0037] 31. Sleeper flat plate; 32. Straight rail; 33. Transition rail; Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] This invention provides an irradiation experimental line mechanism, see details below. Figure 1 The difference between this and existing technologies lies in the following: the experimental line mechanism includes a traveling part and a fixed part. The traveling part consists of an experimental chamber, a suspension chain located at the top of the experimental chamber, and an anchor iron located at the bottom of the experimental chamber. The fixed part includes a track for the suspension chain to travel and a limiting anchor rail located below the track and cooperating with the anchor iron. The track mentioned here actually utilizes the existing track of the irradiation device monitoring line located in the irradiation chamber; it is only necessary to set the suspension chain on the original track.

[0040] In practice, the Monte Carlo simulation program MCNP was used to model and perform mathematical simulations to obtain the surface dose distribution map of the irradiation chamber of the gamma irradiation device of this invention, as shown in the figure. Figure 17 Furthermore, by combining the transmission path of the irradiation device's monitoring line and selecting a suitable irradiation station, a region with relatively uniform dose can be chosen as the location for fixed-point irradiation of the experimental chamber, based on the established transmission path of the irradiation device's monitoring line. Simultaneously, the Monte Carlo simulation program MCNP can simulate the dose distribution within the irradiation chamber, providing a technical basis for the selection and judgment of dose-uniformity areas. Specifically, to meet the operational requirements of achieving a static and stable state for the experimental chamber at both the fixed-point irradiation location and the fixed-point loading and unloading platform at the irradiation chamber entrance and exit, the precise positioning of the experimental chamber has two practical effects: firstly, it improves the inherent safety of irradiation equipment operation during loading and unloading operations, preventing the experimental chamber from shaking under external forces and ensuring safe and reliable loading and unloading operations; secondly, it improves the controllability and repeatability of product irradiation dose during fixed-point irradiation experiments or irradiation processing within the irradiation chamber, achieving a stable and balanced irradiation dose range. This eliminates the operational safety risks and the risk of unstable irradiation dose range caused by the swaying of the experimental chamber under the suspension chain. The overhead conveyor system for the monitoring line was installed and put into use in accordance with the relevant national standards (JB / T9016-2013) when the irradiation equipment was installed, so it will not be described in detail here.

[0041] Example 1

[0042] The experimental box includes a box frame, with an openable box door at the front. Connecting blocks are provided at the top and bottom of the box frame. The connecting block at the top of the box is connected to the suspension chain via a suspension connector. The anchor iron consists of an anchor iron body and a set of anchor tips located below the body. The anchor iron body is made of hollow square steel, and the anchor tips have a wedge-shaped structure.

[0043] Specifically, the experimental chamber includes a frame with an openable door at the front and connecting blocks at the top and bottom. When designing and manufacturing the experimental chamber, the shielding effect of metal materials on gamma rays should be considered, and lightweight alloy materials with certain strength should be selected as much as possible to increase the utilization rate of gamma ray energy. The frame is generally made of aluminum alloy sheet profiles and connected by riveting and welding. The chamber body and door are enclosed with aluminum metal mesh.

[0044] The anchor consists of an anchor body and a set of anchor tips located below the body. The anchor body is made of hollow square steel, typically 45# steel, 80-120mm hollow square steel tubing, with a wall thickness of 8-10mm. The anchor tips have a wedge-shaped structure. The length of the anchor is determined by the dimensions of the experimental chamber's bottom plate and consists of a straight section and wedge-shaped sections at both ends. The straight section is not less than half the length of the bottom plate. The wedge-shaped structures at both ends are made by cutting square steel into right-angled triangles at a 30-degree angle, then splicing and welding them together to form an equilateral triangular wedge-shaped anchor tip. Finally, the anchor is installed on the experimental chamber's bottom plate and locked to it using connecting plate bolts.

[0045] Furthermore, the limiting anchor rail is set on the sleeper plate and is composed of a straight rail and a transition rail. The transition rails are located at both ends of the straight rail, with an angle of 25-45 degrees between them. The net height of the anchor rail is 10-20mm greater than the height of the anchor iron, leaving a gap at the bottom. The width of the rail groove in the straight section of the anchor rail is 3-5mm greater than the width of the anchor iron, and the length of the straight section is greater than or equal to the effective length of the anchor iron (excluding the wedge-shaped sections at both ends). The rail groove allows the anchor iron to pass smoothly and also serves to limit the movement of the anchor rail, thereby stabilizing the test chamber and facilitating subsequent operations.

[0046] During implementation, when the experimental chamber travels to the designated point along the suspension chain, the anchor iron automatically enters the anchor rail along the guide rail. When the anchor iron and the straight section of the anchor rail are fully aligned and the limit switch is triggered, the suspension chain control system receives this command and immediately stops and locks. After the anchor iron stops entering the anchor rail, it is limited by the anchor rail, thus stabilizing the experimental chamber at the designated point. This achieves the purpose of stabilizing the chamber at a fixed point and prevents the experimental chamber from swaying due to its suspended state, thereby keeping the experimental chamber in a stable state at the irradiation position or loading / unloading position.

[0047] Example 2

[0048] A method for using an irradiation experimental line mechanism differs from existing technologies in that the method includes the following steps: a) Three measurement planes, denoted as A, E, and C, are set on the two sides and the middle of the experimental chamber. Dosimeters are evenly arranged on the three measurement planes according to a grid. b) After the experimental chamber door is locked, it enters the irradiation chamber via a suspended chain for fixed-point irradiation. When the irradiation processing time is completed, the experimental chamber moves to the unloading platform via the suspended chain and unloads the irradiated dosimeters. c) The dosimeters are measured, all measurement results are recorded, and isodose distribution curves of the three measurement planes are plotted based on the measurement values ​​to obtain the maximum and minimum dose areas, maximum and minimum dose points, and dose values. Subsequent adjustments to the irradiation time and dosimeter arrangement during irradiation processing can improve the controllability and repeatability of the product irradiation dose and achieve a stable and balanced irradiation dose range.

[0049] Furthermore, the adjustment in step c includes the following two parts: (1) Based on the results of the dose distribution test, calculate the relationship between the product's absorbed dose and the master control time (usually output in the form of dose rate, i.e. how much time is required to absorb 1kGy), and then calculate the time required to meet the product's dose requirements, which is the irradiation time.

[0050] (2) After the time is set, dosimeters still need to be deployed to monitor the actual absorbed dose of the product irradiation in order to determine whether the final irradiation dose of the product is qualified. Based on the dose distribution test results, dosimeters can be deployed in the identified minimum and maximum dose areas to monitor the actual absorbed dose of the product irradiation.

[0051] Specifically, in step a, the three measurement planes are selected from the leftmost, rightmost, and middle sides of the experimental chamber, respectively, and are denoted as A, E, and C. The three measurement planes are parallel to each other. Dosimeters are arranged on the measurement planes according to a 10cm×10cm grid. To meet the requirements of data repeatability and reproducibility, the dose measurement should be repeated at least three times. Potassium dichromate or silver dichromate dosimeters are selected. In step b, during fixed-point radiation, the irradiation time is 2 hours. After 1 hour of irradiation, the face is rotated 180°. This process is repeated at least 3 times. The transmission speed of the suspension chain is fixed at 4-6 minutes, preferably 5 minutes. The transmission process cannot be interrupted.

[0052] In step c, the average absorbed dose for each dose region is calculated based on the measurement results. variance s 2 Z; Determine the pooled variance s for all dose regions. overall Then, the minimum distinguishable factor δ is calculated. The calculation process is illustrated below using specific product dose distribution test results, which are shown in the table below:

[0053]

[0054]

[0055]

[0056] D i，z This is the measurement value of the i-th dosimeter in dose region z, which has undergone n measurements. z n z Subsequent independent measurements; the expected average absorbed dose for each dose region z is calculated according to formula (1). The variance s of the average absorbed dose in each dose region is calculated according to formula (2). 2 Z s 2 Z The CV value can be used to determine whether the changes in each dose region are similar. If the changes in the average dose in each dose region can be considered similar, then the pooled variance s of all dose regions is... overall s overall It can be calculated according to formula (3). Finally, the minimum distinguishing factor δ is calculated according to formula (4).

[0057]

[0058]

[0059]

[0060]

[0061]

[0062] In the formula:

[0063] —The average absorbed dose in the dose region;

[0064] D i，Z —The measurement value of the i-th dosimeter in dose region z;

[0065] n z n z —The number of repeated measurements for dose region z; in this example, the number of repeated measurements is 3.

[0066] s 2 Z s 2 Z —The variance of the average absorbed dose for each dose region;

[0067] Ztotal — Total number of dose zones;

[0068] N—Total number of dose measurements;

[0069] k — Coverage factor.

[0070] When the average dose in a certain dose region Less than or equal to Therefore, this region is the statistically equivalent maximum dose region; when the average dose of a certain dose region... Greater than or equal to Therefore, the equivalent minimum dose area is not statistically analyzed in this region. Then, based on the dose distribution test structure, dose distribution maps of three measurement planes can be drawn. In the dose distribution maps, the maximum and minimum dose areas, maximum and minimum dose points, and dose values ​​can be obtained intuitively and accurately.

[0071] The dose non-uniformity (DUR) of the product irradiation is calculated based on the measured minimum average absorbed dose and maximum absorbed dose.

[0072]

[0073] In actual processing, the expected non-uniformity can be calculated based on the specific location of the product placement to determine whether the irradiation dose of the product meets the requirements. Reducing the space for product placement can lower the DUR, but it will also lead to a waste of processing capacity.

[0074] During routine irradiation processing, the dose rate of product irradiation is calculated based on the measured minimum average dose, i.e., the time required to absorb 1 kGy. Multiplying this parameter by the minimum dose required by the product gives the minimum theoretical irradiation time. When a maximum dose requirement exists for the product, the maximum theoretical irradiation time can be calculated by combining the dose non-uniformity (DUR) determined by dose distribution testing. The actual irradiation schedule should be within the range of the minimum and maximum theoretical control times. During product irradiation, the actual absorbed dose needs to be monitored to determine whether the irradiation results are acceptable. Dosimeters can be placed in the identified maximum and minimum equivalent regions. The dose values ​​in these regions represent the minimum and maximum absorbed doses during product irradiation. By monitoring the dose values ​​in these regions, it can be determined whether the actual absorbed dose of the product meets the requirements.

[0075] Implementation 3

[0076] In one specific embodiment, a reliability assessment (IQ) report is conducted on the safety performance, technical performance, and operational performance of the existing monitoring line transmission system to confirm the maximum load capacity and safe load capacity of the suspension chain system, i.e., the safe load capacity of the irradiation dose experimental line.

[0077] Then, based on the safe load capacity, the space dimensions along the irradiation chamber's suspension chain, the dimensions of representative product boxes, and product density, the dimensions and materials of the experimental chamber are determined. When designing and manufacturing the experimental chamber, the shielding effect of metal materials on gamma rays should be considered, and lightweight alloy materials with sufficient strength should be selected to increase the utilization rate of gamma ray energy. The frame is generally made of aluminum alloy sheet profiles, and the chamber body and door are enclosed with metal mesh. Considering the comprehensive on-site conditions, the dimensions of the experimental chamber meet the requirements for safety, load capacity, radiation utilization rate, and effective volume. The dimensions of the experimental chamber are set at 400*450*500MM (length*width*height), and the experimental chamber is manufactured using a general riveting and welding process.

[0078] The design and fabrication of the anchor iron begins with determining the material of the square steel for the anchor iron based on the dimensions of the experimental chamber's bottom plate and the maximum load capacity of the chamber. The material is generally 45# steel, 80-120mm hollow square steel tubing with a wall thickness of 8-10mm. The length is determined by the dimensions of the experimental chamber's bottom plate and consists of a straight section and wedge-shaped sections at both ends. The straight section is no less than half the length of the bottom plate, and the wedge-shaped sections at both ends have an angle of 30 degrees. The anchor iron is fabricated by cutting and welding the square steel. The next step is to install the anchor iron on the experimental chamber's bottom plate and lock it in place using connecting plate bolts.

[0079] The anchor rail consists of transition rails at both ends and a straight rail, connected to the sleeper plate. It is made of steel plate with a thickness of not less than 10mm. The net height of the anchor rail is 10-20mm greater than the height of the anchor, with a gap at the bottom. The transition section of the anchor rail consists of two 30° inclined plates on both sides. Theoretically, the width of the rail entry is greater than the swing width of the suspended test box, generally 150*20mm or determined after actual measurement and theoretical calculation verification. The width of the rail groove of the straight section of the anchor rail is 3-5mm greater than the width of the anchor, and the length of the straight section is greater than or equal to the effective length of the anchor (excluding the wedge sections at both ends). The rail groove allows the anchor to pass smoothly and also serves to limit the movement of the anchor rail, thereby stabilizing the test box and facilitating subsequent operations. The straight section of the anchor rail is connected to the transition rail section as a whole and bolted to the sleeper plate.

[0080] After the components above are manufactured in the third step, the installation and installation verification (IQ) phase begins, and an IQ report is submitted to confirm that they meet the design requirements before proceeding to the next stage of work.

[0081] A plan should be developed for dose field testing, and after implementation, the data obtained should be collected, analyzed, and submitted as an operational verification report to provide key technical data support for the irradiation process method in the experimental line operation.

[0082] Corrugated cardboard with a density of 0.10 g / cm³ was used as a homogeneous simulation product to conduct dose distribution tests in the experimental chamber. The corrugated cardboard was uniformly filled throughout the experimental chamber, and gamma rays exhibited exponential decay in the material (e.g., gamma rays decayed exponentially within the material). Figure 8As shown in the figure, when bi-sided irradiation is used, the minimum dose region falls on the mid-section of the product along the ray penetration direction, as shown in the figure. Figure 9 As shown.

[0083] To measure the minimum and maximum dose of the product, three planes are marked on the product along the X-ray penetration direction: the left and right surfaces A and E, and the mid-section surface C, as shown. Figure 10 As shown, dosimeters were arranged in a 10cm × 10cm grid on three planes to monitor the absorbed radiation dose of the entire experimental chamber. Potassium dichromate (silver) dosimeters were selected, as they are of moderate size, have good measurement accuracy and repeatability, and are suitable for dose distribution testing in the experimental chamber.

[0084] Based on MCNP simulations, when the cobalt source activity of the gamma irradiation device is 2.5 MCI and the product loading density on the production line is approximately 0.10 g / cm³, the dose rate at the irradiation station in the experimental chamber is approximately 3.5 kGy / h. The OQ dose distribution test has no specific requirements regarding the dose value. Considering that the dose for common small-dose products is typically 5-10 kGy, the irradiation time for the OQ dose distribution test was set to 2 hours, with a 1-hour interval during the irradiation. This process was repeated three times to meet the requirements of data repeatability and reproducibility. During the test, the transmission speed of the monitoring line was fixed, and the transmission process could not be interrupted.

[0085] After irradiation, all dosimeters were removed and measurements were taken, and all results were recorded. The average absorbed dose for each dose zone was calculated according to the method described in ASTM / ISO 52303:2015. See formula (1); variance s 2 Z See formula (2); determine the pooled variance s for all dose regions. overall See formula (3); then calculate the minimum distinguishable factor δ, see formula (4).

[0086]

[0087]

[0088]

[0089]

[0090] In the formula:

[0091] —The average absorbed dose in the dose region;

[0092] D i，Z —The measurement value of the i-th dosimeter in dose region z;

[0093] n z n z —The number of repeated measurements in dose region z;

[0094] s 2 z s 2 z —The variance of the average absorbed dose for each dose region;

[0095] Ztotal — Total number of dose zones;

[0096] N—Total number of dose measurements;

[0097] k — Coverage factor.

[0098] When the average dose in a certain dose region Less than or equal to Therefore, this region is the statistically equivalent maximum dose region; when the average dose of a certain dose region... Greater than or equal to Therefore, the region where the statistically equivalent minimum dose is not calculated is not included. Identifying the statistically equivalent maximum and minimum dose regions helps in the selection and placement of dosimeters during product irradiation. Based on the dose distribution test results, dose distribution maps of the three planes of the ACE are plotted.

[0099] The isodose distribution curves of the three surfaces above provide a clear and accurate view of the maximum and minimum dose regions, maximum and minimum dose points (XYZ), and dose values.

[0100] The dose nonuniformity (DUR) of the product irradiation is calculated based on the measured minimum average absorbed dose and maximum absorbed dose, as shown in formula (5). The dose nonuniformity characterizes the degree of dose nonuniformity at all locations in the test chamber. Since the product chamber is much smaller than the test chamber, the expected nonuniformity can be calculated based on the specific location of the product during actual processing. This is used to determine whether the irradiation dose of the product meets the requirements. Reducing the space for product placement can lower the DUR, but it will also lead to a waste of processing capacity.

[0101]

[0102] Meanwhile, the dose distribution experiment can also determine the relationship between the minimum dose region, the maximum dose region, and time. This relationship can be used to verify the MCNP simulation results. The MCNP simulation results verified by actual testing can be well used to guide daily irradiation processing.

[0103] Dose distribution experiments are a prerequisite for conducting irradiation dose experiments. It is necessary to test and analyze the dose field distribution of the experimental chamber to obtain relevant technical indicators, such as the statistical equivalent maximum dose region, the equivalent minimum dose region, dose non-uniformity, and the relationship between master control time and absorbed dose. These indicators provide a technical basis for the irradiation process design of irradiation dose experiments.

[0104] The application of this experimental line effectively realizes the function of conducting irradiation dose experiments, providing experimental conditions for medical products to meet the relevant clauses of the GB18280 / ISO11137 standard. It extends the irradiation dose range of industrial gamma irradiation devices (achieving smaller, precisely controllable minimum doses), extends the process chain of irradiation plants (medical product irradiation dose verification, dose setting, etc.), and provides the necessary irradiation environment, equipment, and processes for irradiation dose experiments and related technical research, effectively improving the technical level and economic benefits of gamma irradiation plants.

[0105] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. An irradiation experimental line mechanism, characterized in that: The experimental line mechanism includes a traveling section and a fixed section. The traveling section includes an experimental box, a suspension chain on top of the experimental box, and an anchor iron on the bottom of the experimental box. The fixed section includes a track for the suspension chain to travel and a limiting anchor rail located below the track and cooperating with the anchor iron. The limiting anchor rail is set on the sleeper plate and is composed of a straight rail and a transition rail. The transition rail is located at both ends of the straight rail, and there is an angle of 25-45 degrees between the transition rail and the straight rail. The net height of the anchor rail is 10-20mm greater than the height of the anchor iron, with a gap at the bottom. The width of the straight section of the anchor rail is 3-5mm wider than the width of the anchor iron, and the length of the straight section is greater than or equal to the length of the anchor iron excluding the wedge-shaped sections at both ends. The rail groove allows the anchor iron to pass smoothly and also limits the anchor rail, so that the experimental box reaches a stable state. The anchor iron consists of a straight section and wedge-shaped sections at both ends. The straight section is not less than 1 / 2 of the length of the bottom plate of the box. The wedge-shaped structure at both ends is made by cutting square steel into right-angled triangles with a 30-degree angle, and then splicing and welding them together to form a wedge-shaped anchor tip with an equilateral triangle cross section. The anchor iron is installed on the bottom plate of the experimental box and is locked to the bottom plate of the experimental box by connecting block bolts.

2. The irradiation experimental line mechanism according to claim 1, characterized in that: The experimental chamber includes a frame. The front of the box frame is equipped with an openable door, and the top and bottom of the box frame are equipped with connecting blocks.

3. The method of using the irradiation experimental wire mechanism according to claim 1, characterized in that: The method of use includes the following steps: a) Set up three measurement planes on the two sides and the middle of the experimental chamber, and evenly arrange dosimeters on the three measurement planes according to the grid; b) After locking the door of the experimental chamber, it enters the irradiation chamber with the suspension chain for fixed-point irradiation. When the irradiation processing time is completed, the experimental chamber moves with the suspension chain to the unloading platform and unloads the irradiated dosimeters; c) Measure the dosimeters, record all measurement results, and draw the isodose distribution curve of the three measurement planes based on the measurement values ​​to obtain the maximum and minimum dose areas, maximum and minimum dose points and dose values. Subsequent adjustments to the irradiation time and dosimeter arrangement during irradiation processing can improve the controllability and repeatability of the product irradiation dose and achieve a stable and balanced irradiation dose range.

4. The method of using the irradiation experimental line mechanism according to claim 3, characterized in that: In step a, dosimeters are arranged in a 10cm×10cm grid. Potassium dichromate or silver dichromate dosimeters are selected. In step b, during fixed-point radiation, the irradiation time is 2 hours. After 1 hour of irradiation, the dosimeters are rotated 180°. This process is repeated 3 times. The transmission speed of the suspension chain is fixed at 4-6 minutes. The transmission process cannot be interrupted.

5. The method of using the irradiation experimental line mechanism according to claim 3, characterized in that: In step c, based on the measurement results, Calculate the average absorbed dose for each dose region. Variance S 2 Z; Determine the pooled variance S across all dose regions. overall Then calculate the minimum distinguishable factor δ; In the formula: —The average absorbed dose in the dose region; D i，Z —The measurement value of the i-th dosimeter in dose region z; n z n z —The number of repeated measurements in dose region z; S 2 Z—The variance of the average absorbed dose in each dose region; Ztotal — Total number of dose zones; N—Total number of dose measurements; k — Coverage factor; When the average dose in a certain dose region Less than or equal to Therefore, this region is the statistically equivalent maximum dose region; when the average dose of a certain dose region... Greater than or equal to Therefore, the region where the equivalent minimum dose is not statistically analyzed is not included.

6. The method of using the irradiation experimental line mechanism according to claim 3, characterized in that: The dose non-uniformity (DUR) of the product irradiation is calculated based on the measured minimum average absorbed dose and maximum absorbed dose.

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