Radiological protection container for a measuring device for radiological measurements

Abstract

This invention relates to a radiation protection container (11) for measuring radiation density or fill level (1). According to the invention, the radiation protection container (11) is based on two bodies (110, 111), each connected to the other via planar surfaces (1101, 1111), for example by welding, thereby defining a plane (E). A hollow radiation conductor (113) extends in the plane (E) for focused irradiation, wherein the hollow radiation conductor (113) is formed by recesses in the surfaces (1101, 1111) of the bodies. According to the present invention, the radiation protection container (11) includes radiation-absorbing structures (114, 114', 114"), which are formed by mutually abutting recesses and complementary protrusions located in the main body surface (1101, 1111). An advantage of this two-part design is that a steel-based refractory body (110, 111) can be used, wherein the recesses and protrusions of the hollow radiation conductor (113) and the radiation-absorbing structures (114, 114', 114") can be produced by surface processing. According to the present invention, the radiation-absorbing structures (114, 114', 114") ensure that no radiation leaves the radiation protection container (11) laterally.

Description

Technical Field

[0001] This invention relates to a radiation protection container for measuring radiation density or fill level. Background Technology

[0002] In automation technology, particularly in process automation, field devices are frequently used to detect and / or modify process variables. To detect process variables, sensors are used, such as fill level measuring instruments, flow measuring instruments, pressure and temperature measuring instruments, pH redox potential measuring instruments, conductivity measuring instruments, etc. They detect corresponding process variables, such as fill level, flow rate, pressure, temperature, pH value, redox potential, or conductivity. Actuators, such as valves or pumps, can change the flow rate of liquid in a piping section or the fill level in a container, and actuators are used to influence process variables. Within the scope of this invention, the term "container" also refers to an unsealed container, such as a pool, lake, or flowing body of water. All instruments used near the process and providing or processing process-related information are collectively referred to as field devices. Various such field devices are manufactured and sold by Endress+Hauser.

[0003] In the case of density or fill level measurement, field equipment is often used, and the measurement method is based on radiation measurement. In this measurement method, radioactive radiation (e.g., gamma radiation from a cesium or cobalt source) is emitted by a radioactive radiation source of the measuring instrument and guided through a container containing the fill material to be measured. After passing through the container, the intensity of the transmitted radiation is detected by the detector unit of the measuring instrument. By evaluating the detector signal, the transmitted portion of the emitted radiation intensity is determined. Based on this, the density or fill level of the fill material is inferred. In this case, the transmitted portion of the radioactive radiation power cannot be directly detected after passing through the container, but must first be converted into electromagnetic radiation within the spectral range by a material suitable for this purpose before the radiation power can be detected by a photomultiplier (or alternatively, one or more avalanche photodiodes) within the detector unit. Materials with this property are called scintillation materials. In particular, polystyrene has this scintillation property. Only radiation within the spectral range can be detected by a photomultiplier. Radioactive measurement fill level or density measuring instruments are known from the prior art. For example, the basic operating principle is described in patent specification EP2 208 031B1.

[0004] Radiation shielding containers are used for the safe transport of radiation sources and their safe measurement operations. On the one hand, they must be designed to protect the radiation source from damage and unauthorized removal. On the other hand, the radiation shielding container must provide radiation shielding against the surrounding environment. For this purpose, according to existing technology, radiation shielding containers are made of lead or another material that provides a seal against radioactivity.

[0005] For measurement operations, the radiation shielding container has an open end region, allowing the focused useful beam to exit the container in the direction of the detector unit. The end region located at the end of the radiation waveguide can be sealed within the radiation shielding container for the secure storage and transport of the source. In this case, sealing can occur via a movable shielding opener or a rotatable / displaceable radiation source. During the production of the shielded radiation shielding container, the radiation waveguide is created by recesses during casting of a lead-based or cast steel substrate, or subsequently by milling or drilling into the cast substrate.

[0006] Radiation protection containers made of lead have significant disadvantages, especially when used at high ambient temperatures and / or relative to their refractory properties. Therefore, it is obvious that the lead-based matrix of radiation protection containers should be replaced with a refractory / high-temperature resistant matrix made of steel or tungsten. However, if the production of such radiation protection containers from cast steel were similar to that from lead (which is inherently impossible in the case of tungsten), then the production of such containers from cast steel would be significantly uneconomical compared to the considerably more advantageous and readily cast lead.

[0007] When solid raw materials (e.g., in the form of extruded profiles or round blanks) are used to produce radiation shielding containers, the necessary radiation waveguides (for directional radiation emission along the beam axis) inside the container can be manufactured solely through complex milling, drilling, or electrical discharge machining. However, given the required shielding thickness, in these cases, the radiation waveguides must be embedded several centimeters deep, which is technically very complex and expensive. From an economic standpoint, additive methods for producing the shield (i.e., such as 3D printing) are also not feasible. Summary of the Invention

[0008] Therefore, the present invention is based on the task of providing a safe and temperature-resistant radiation protection container that can be produced economically.

[0009] This invention achieves this task through a radiation protection container for a radiation source in a measurement system used for measuring radiation density or fill level. For this purpose, the radiation protection container includes:

[0010] - A first substrate having a first planar surface.

[0011] - A second substrate having a second planar surface.

[0012] - A first connecting device that connects a first substrate and a second substrate to the surface in a form-fit manner, such that the surface defines a flat plane.

[0013] - A direct-axis radiating waveguide extending in the plane, the direct-axis radiating waveguide being formed by corresponding recesses in at least one of the surfaces of the two substrates, the direct-axis radiating waveguide having

[0014] ○ The first opening region, on which a radiation source can be fixed, and

[0015] ○Second opening region,

[0016] - At least one first radiation absorbing structure, which is formed by a depression and complementary protrusion in a first surface and a second surface, respectively, such that the first radiation absorbing structure extends in the plane and travels from the radiation waveguide.

[0017] This two-part design of the radiation shielding container according to the invention allows the use of heat-resistant steel as the manufacturing material for the substrate, wherein the radiation waveguide can be produced with minimal effort, for example, by surface processing, prior to the connection of the substrate. In the connected state of the substrate or during measurement operations of the measurement system, according to the invention, shielding is ensured by the radiation-absorbing structure, preventing lateral escape of radiation along the plane.

[0018] To ensure that the radiation shielding container shields the radiation waveguide on both sides, preventing radiation from escaping, it is advantageous that the radiation-absorbing structure, in each case, has a profile on both sides (particularly symmetrically) relative to the beam axis in the plane, extending from the radiation waveguide. In this case, the radiation-absorbing structure can be designed to have a profile with a circular segment shape curving up to 90° towards the first open end region in the plane about the beam axis, so as to achieve complete shielding of + / -90° on both sides of the radiation waveguide extending from the radiation source. If the radiation shielding container includes not only one radiation-absorbing structure arranged in the plane, but multiple radiation-absorbing structures arranged in the plane, the shielding can be further enhanced, wherein each radiation-absorbing structure is arranged at an increased distance from the first open end region relative to the beam axis. The cross-section of the radiation-absorbing structure is determined by its manufacturing method. In terms of shielding technology, a rectangular cross-section is most effective for the radiation-absorbing structure.

[0019] Within the framework of this invention, the method of connecting the two substrates is not strictly defined. In the case of a steel substrate, the first connecting device can be designed, for example, as a welded connection. However, in the simplest case, the first connecting device can also be designed, for example, as a threaded connection.

[0020] Based on the radiation protection container according to the invention, a measurement system for determining the density and / or filling level of the filling material located in the container can be implemented by the following additional components, wherein, for this purpose, the radiation protection container is attached to the container such that the second open end region of the radiation waveguide, and therefore the beam axis, is oriented in the direction of the container:

[0021] - A radioactive radiation source, which can be secured to the first open end region of the radiation waveguide, for example, by a corresponding insert.

[0022] - A detector unit that can be attached to the container on the beam axis so as to be opposite the radiation source in order to detect the radiation intensity of the source after the radiation has passed through the filling material, and

[0023] - Evaluation unit, which is designed to determine the density and / or filling level of the filling material in the container based on the received radiation intensity.

[0024] The radiation source or its corresponding insert can be designed to correspond to the threads on the substrate, having corresponding internal or external threads, so that the radiation source can be secured to the radiation shielding container via the resulting threaded connection. The threaded connection can be implemented such that the thread axis of the threaded connection extends parallel to the beam axis of the radiation waveguide. Securely fastening the radiation source to the radiation shielding container via a threaded connection offers the advantage that the radiation shielding container can be equipped with an opening / closing function for securely transporting the radiation source. For this purpose, the radiation source will be arranged with a defined radial offset about the thread axis of the threaded connection, and the radiation waveguide will be arranged in the plane such that its beam axis has the same defined radial offset about the thread axis of the threaded connection as the radial offset of the radiation source about the thread axis. Therefore, depending on how far the insert or radiation source is screwed in, the radiation source aligns with the beam axis of the radiation waveguide. This corresponds to the open state of the opening / closing. If the threaded connection is not screwed in to this position, causing the radiation source to align with the beam axis of the radiation waveguide, this corresponds to the closed state of the opening / closing. In this regard, the best approach is to design the threaded connection in such a way that when the threaded connection is in the end stop position, the radiation source is located in the beam axis of the radiation waveguide, so that the switch opens when the threaded connection is in the end stop position. Attached Figure Description

[0025] The invention will be explained in more detail with reference to the following figures, in which:

[0026] Figure 1 The measuring instrument for measuring radiation on the container is shown.

[0027] Figure 2 A first cross-sectional view of the radiation protection container according to the present invention is shown, and

[0028] Figure 3 A second cross-sectional view of the radiation protection container according to the present invention is shown. Detailed Implementation

[0029] To gain a general understanding of radiometric density and fill level measurements, Figure 1 A container 2 filled with filler material 1 is shown. Depending on the application of container 2 or the type of filler material 1, the density and / or filling level of filler material 1 in container 2 must be determined. For this purpose, a measurement system based on radiation measurement is arranged on container 2. In this case, the measurement system includes a radiation source 10, a detector unit 12, and an evaluation unit 13 downstream of the detector unit 12. The radiation source 10 is located in a radiation protection container 11, which, when open, allows radiation from the radiation source 10 to exit along a defined beam axis a.

[0030] To measure density or fill level, radiation shielding container 11 and detector unit 12 are arranged such that the beam axis a of radiation shielding container 11 points towards fill material 1. Furthermore, detector unit 12 is arranged relative to container 2 and radiation shielding container 11, such that detector unit 12 is positioned as centrally as possible on the beam axis a of radiation source 10 to detect the intensity of radiation after passing through fill material 1. For this purpose, radiation shielding container 11 and detector unit 12 can be directly mounted on container 2 or indirectly mounted on corresponding freestanding supports. Based on this radiation intensity, indirectly determined by a scintillator, evaluation unit 13 can determine density or fill level as needed, for example, after corresponding calibration of container 2.

[0031] Depending on the application, radiation measurement systems are designed to be fire-resistant for measurement operations, as specified, for example, in the IEC 62598:2011 series of standards. Therefore, refer to... Figure 2 and Figure 3 The possibility of producing the radiation protection container 11 with minimal effort according to the present invention is explained in more detail, without the need for refractory tungsten as a manufacturing material:

[0032] The radiation protection container 11 shown here for the radiation source 10 or for the insert 3 into which the radiation source 10 is embedded is based on two cubic bases 110, 111. For clarity, in Figure 2Only the first substrate 110 is shown. Each of the two substrates 110 and 111 has a first surface 1101 or a second surface 1111, wherein the surfaces 1101 and 1111, except for the radiating waveguide 113 and the radiating absorption structures 114, 114', 114" are formed in a planar manner. In this case, the planar surfaces 1101 and 1111 in the illustrated embodiment are each formed on one side surface of a free cube.

[0033] Figure 3 This is a cross-sectional view of the radiation shielding container 11, orthogonal to axis a of the radiation waveguide 113 and extending at a horizontal height between the first absorbing structure 114 and the first open end region 1130. It is clearly visible here that, in the completed state of the radiation shielding container 11, the substrates 110 and 111 are fastened together such that the primarily planar surfaces 1101 and 1111, except for the radiation waveguide 113, are abutted against each other in a form-fitting manner within manufacturing tolerances, such that the planar regions span the corresponding flat plane E. Since the substrates 110 and 111 can be made of steel, they can be welded, for example, along the edges of surfaces 1101 and 1111 to form the radiation shielding container 11. However, it is also conceivable to connect the substrates 110 and 111 by threaded connection 14. Figure 2 As shown, for this purpose, the bases 110 and 111 may each be provided with four screw channels or four internal threads extending orthogonally to the plane E, wherein the channel of one of the bases 110 and 111 is intended to be arranged in a consistent manner with respect to the channel or internal thread of the other base 110 and 111.

[0034] Inside the assembled radiation protection container 11, the radiation waveguide 113 is formed by a recess formed by the relative mirror symmetry of the surfaces 1101 and 1111 of the substrate 110 and 111, such that the radiation waveguide 113 extends in plane E from the first open end region 1130 on the cube to the opposite end region 1131 of the cube.

[0035] exist Figure 2 or Figure 3 In the illustrated embodiment, the recess of the radiating waveguide 113 has a rectangular cross-section, so that the resulting radiating waveguide 113 also has a rectangular cross-section. Conversely, in contrast to the illustrated embodiment, it is also conceivable that the radiating waveguide 113 has a circular cross-section, and for this purpose, the corresponding recesses each have a semi-circular cross-section. As an alternative example of the illustrated variant, it is also conceivable that the radiating waveguide 113 is formed only by a recess in one of the two surfaces 1101, 1111. Regardless of the cross-sectional shape of the radiating waveguide 113, the radiating waveguide 113 can be designed to improve beam focusing, such that the radiating waveguide 113 widens towards the second opening end region 1131, as... Figure 2As shown. The recess for the radiating waveguide 113 can be formed, for example, by subsequently machining the surfaces 1101 and 1111 using a corresponding machining method.

[0036] Furthermore, in the regions of radiation-absorbing structures 114, 114', and 114" respectively, since the radiation-absorbing structures 114, 114', and 114" are formed by corresponding protrusions in one surface and corresponding recesses in the other surface 1101, the surfaces 1101 and 1111 are adjacent to each other in a form-fit manner after the two substrates 110 and 111 are joined within the tolerance range of the corresponding manufacturing method. Figure 3 As can be seen, in the illustrated embodiment, the protrusions of the radiation absorption structures 114, 114', and 114' are located in the first surface 1101 or the first substrate 110, wherein the second substrate 111 has a recess in the second surface 1111 corresponding to the protrusion, such as... Figure 3 As shown.

[0037] Figure 2 and Figure 3 The variant of the radiation shielding container 11 shown includes three radiation-absorbing structures 114, 114', and 114'", which are arranged along the beam axis a at an increased distance from the first opening region 1130. In this case, the shapes formed by the radiation-absorbing structures 114, 114', and 114'" in plane E are as follows: Figure 2 As shown, the radiation-absorbing structures 114, 114', and 114" therefore travel orthogonally from the beam axis a on both sides in plane E, wherein the radiation-absorbing structures 114, 114', and 114" are curved toward the first opening end region 1130 in the shape of circular segments, and the distance from the beam axis a increases. In this case, the radiation-absorbing structure 114 closest to the first opening end region 1130 and the intermediate radiation-absorbing structure 114' are each curved by 90°. The radiation-absorbing structure 114" arranged closest to the second opening end region 1131 has a curvature of approximately 30° toward the first opening end region 1130.

[0038] As a result of this design, once the radiation source 10 is attached to the first open end region 1130, the radiation absorbing structures 114, 114', 114" prevent lateral radiation from leaving the radiation shielding container 11 along the plane E, even if possible tolerances during manufacturing or during the connection of the substrates 110, 111 result in a lack of form fit between the surfaces 1101, 1111. The recesses and protrusions of the radiation absorbing structures 114, 114', 114" can be reformulated, for example, by machining the surfaces 1101, 1111 using corresponding processing methods before connecting the substrates 110, 111.

[0039] like Figure 2As shown, in this variant, the radiation source 10 is enclosed in a rotating insert 3 for fastening to the first open end region 1130. In this case, the insert 3 is designed such that the radiation source 10 within the insert 3 is shielded on all sides by a tungsten-based sheath 101, except for the opening towards the first open end region 1130 of the radiation waveguide 113. In this context, the term "opening" is also understood to refer to an area lined with a corresponding material that can be penetrated by the radiation from the radiation source 10 with low loss, such as 1.5 mm thick steel.

[0040] The rotating insert 3 and the substrates 110 and 111 are designed with corresponding threaded connections 14 to allow the rotating insert 3 to be screwed onto the radiation shielding container 11, such that the opening of the radiation source 10 within the rotating insert 3 is adjacent to the first open end region 1130 of the radiation waveguide 113. For this purpose, the radiation source 10 is arranged within the rotating insert 3 and on the threaded axis of the threaded connection 14. Furthermore, the threaded connection 14 is designed such that its threaded axis extends in alignment with the beam axis a of the radiation waveguide 113. Therefore, in the installed state, the radiation source 10 is also automatically positioned within the beam axis a of the radiation waveguide 113, such that the radiation source 10 radiates along its beam axis a only through the second open end region 1131 of the radiation waveguide.

[0041] To achieve the threaded connection 14, in the illustrated variant, the rotary insert 3 includes a corresponding external thread, while the bases 110 and 111 form corresponding internal threads. It is apparent within the scope of the invention that, as an alternative example illustrated, the rotary insert 3 may also include an internal thread, and the radiation protection container 11 may include the external thread of the threaded connection 14.

[0042] Because in Figure 2In the variant shown, the thread axis of the screw thread 14 extends in alignment with the beam axis a of the radiation waveguide 113, and the radiation source 10 is located within the rotating insert 3 and on the thread axis of the screw thread 14, so the radiation source 10 automatically radiates once screwed in (even before screwing is complete). Conversely, an opener / closer function for transporting the radiation shielding container 11 can be achieved if the beam axis a of the radiation waveguide 113 extends parallel to the thread axis of the screw thread 14, but with a defined radial offset. To achieve the opener / closer function, in this case, the radiation source 10 is also arranged within the rotating insert 3 and has the same radial offset with respect to the thread axis of the threaded connection 14. As a result, the resulting opener / closer is only opened when the rotating insert 3 is screwed into the radiation shielding container 11 to the extent that the radiation source 10 is located on the beam axis a of the radiation waveguide 113. Ideally, the opening and closing mechanism is implemented such that when the rotating insert 3 is screwed into the radiation protection container 11 until it reaches a defined end stop, the opening and closing mechanism opens. To prevent misuse of the radiation source 10 or accidents related to the radiation source 10, the rotating insert 3 and the radiation protection container 11 may also be provided with a closing mechanism 4, through which the rotating insert 3 can be fixed on the radiation protection container 11 at the position where the opening and closing mechanism is closed or at a position where the radiation source 10 is not located on the beam axis a of the radiation waveguide 113.

[0043] List of reference numerals

[0044] 1. Filling material

[0045] 2 containers

[0046] 3 Rotary inserts

[0047] 4 Closing Mechanism

[0048] 10 radioactive radiation sources

[0049] 11 Radiation Protection Container

[0050] 12 detector units

[0051] 13 assessment units

[0052] 14 Threaded Connection

[0053] 101 Sheath

[0054] 110 First matrix

[0055] 111 Second matrix

[0056] 112 Connecting Device

[0057] 113 radiating waveguide

[0058] 114 radiation absorption structure

[0059] 1101 First Surface

[0060] 1111 Second Surface

[0061] 1130 First Opening End Region

[0062] 1131 Second Opening End Region

[0063] a beam axis

[0064] E plane

Claims

1. A radiation protection container (11) for a radiation source (10) of a measurement system for measuring radiation density or fill level (1), comprising: - A first substrate (110), the first substrate (110) having a first planar surface (1101), - Second substrate (111), the second substrate (111) having a second planar surface (1111), - A first connecting device (112) connects the first substrate (110) and the second substrate (111) to the first planar surface (1101) and the second planar surface (1111) in a form-fit manner, such that the first planar surface (1101) and the second planar surface (1111) define a flat plane (E). - A direct-axis radiating waveguide (113) extending in the plane (E), the direct-axis radiating waveguide (113) being formed from the two substrates (110, 111), the direct-axis radiating waveguide (113) having ○ First opening end region (1130), the radiation source (10) can be fixed to the first opening end region (1130), and ○Second opening region (1131), - At least one first radiation absorbing structure (114), the at least one first radiation absorbing structure (114) being formed by a recess and complementary protrusion in the first planar surface (1101) and the second planar surface (1111), such that the first radiation absorbing structure (114) extends in the plane (E) and travels from the radiation waveguide (113).

2. The radiation protection container (11) according to claim 1, wherein, The radiation-absorbing structure (114) has a profile that extends from the radiation waveguide (113) in each case.

3. The radiation protection container (11) according to claim 2, wherein, The radiation absorption structure (114) in each case has a profile that travels from the radiation waveguide (113) in a manner symmetrical about both sides of the beam axis (a).

4. The radiation protection container according to claim 1 or claim 2, wherein, The radiation-absorbing structure (114) has a profile in the plane (E) relative to the beam axis (a), the profile being curved up to 90° toward the first opening end region (1130) in the shape of a circular segment.

5. The radiation protection container according to claim 1 or claim 2, comprising: - Three radiation-absorbing structures (114, 114', 114") are arranged in the plane (E), and the three radiation-absorbing structures (114, 114', 114") are respectively arranged at an increased distance from the first opening end region (1130) relative to the beam axis (a).

6. The radiation protection container according to claim 1 or claim 2, wherein, The radiation-absorbing structure (114, 114', 114") has a rectangular cross-section.

7. The radiation protection container according to claim 1 or claim 2, wherein, The first substrate (110) and / or the second substrate (111) are made of steel.

8. The radiation protection container according to claim 1 or claim 2, wherein, The first connecting device (112) is configured as a threaded connection.

9. The radiation protection container according to claim 7, wherein, The first connecting device (112) is configured for a welded connection.

10. A measurement system (1) for determining the density and / or filling level of a filler material (2) located in a container (3) by means of radiometric measurement, comprising: - The radiation protection container (11) according to any one of the preceding claims is capable of being attached relative to the container (3) such that the second open end region (1131) of the radiation waveguide (113) is guided away from the container (3). - A radioactive radiation source (10), said radioactive radiation source (10) being fixed to the first open end region (1130) of the radiation waveguide (113), - Detector unit (12), which is capable of being attached to the container (3) on the beam axis (a) in a manner opposite to the radiation source (10) in order to detect the radiation intensity of the radiation source (10) after passing through the filling material (2). - Evaluation unit (13), which is designed to determine the density and / or filling level of the filling material in the container (3) based on the received radiation intensity.

11. The measurement system according to claim 10, wherein, The radiation source (10) can be fastened to the radiation protection container (11) by a threaded connection (14) such that the thread axis of the threaded connection (14) extends parallel to the beam axis (a).

12. The measurement system according to claim 11, wherein, The radiation source (10) is arranged to have a radial offset defined relative to the threaded axis of the threaded connection (14), and wherein the radiation waveguide (113) is arranged such that its beam axis (a) has the defined radial offset relative to the threaded axis of the threaded connection (14).

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