DOSE MEASURING DEVICE FOR THE MEASUREMENT OF A RADIATION DOSE AND MEASUREMENT METHOD FOR DETERMINING THE RADIATION DOSE APPLIED DURING PASTEURIZATION AND/OR STERILIZATION OF PARTICULATE MATERIAL

Abstract

Disclosed is a dose measuring device for the measurement of a radiation dose which comprises a radiation-sensitive measuring film and a base body, wherein the measuring film is wound onto the base body in some areas. Furthermore, a measurement method using such a dose measuring device is disclosed to determine the radiation dose applied during the pasteurization and/or sterilization of particulate material.

Claims

1. A dose measuring device for the measurement of a radiation dose comprising: a radiation-sensitive measuring film; and, a base body, wherein the measuring film is wound onto the base body at least in certain areas, wherein the base body is fabricated from a material having a density which largely corresponds to the density of the particulate material to be treated.

2. The dose measuring device according to claim 1, that the base body has at least one dimension which largely corresponds to at least one dimension of a particulate material to be treated.

3. The dose measuring device according to claim 1, that the base body has a cylinder-like section, wherein the measuring film is advantageously wound on this cylinder-like section.

4. The dose measuring device according to claim 1, that the base body has at least one guide section for guiding the measuring film during winding of the same onto the base body, wherein two guide sections are provide wherein advantageously the measuring film lies between these two guide sections after winding the same onto the base body.

5. The dose measuring device according to claim 1, that the base body is fabricated from a carbon-based material, preferably from a polymer.

6. The dose measuring device according to claim 1, that the base body is fabricated from a material whose chemical structure largely corresponds to the chemical structure of the particulate material to be treated.

7. The dose measuring device according to claim 1, that the measuring film has a thickness of up to 200 m, preferably of 10-50 m.

8. The dose measuring device according to claim 1, that the number of windings of the measuring film on the base body corresponds to 1 to 20, preferably 2 to 10 and particularly preferably 3 to 6.

9. The dose measuring device according to claim 1, that at least one first fixing means is provided for fixing a first end 46 of the measuring film on the base body.

10. The dose measuring device according to claim 1, that at least one second fixing means is provided for fixing the second end of the measuring film.

11. A measurement method using a dose measuring device according to claim 1 to determine the radiation dose applied during pasteurization and/or sterilization of particulate material including the following steps: a) Mixing the particulate material to be treated using several dose measuring devices to form a mixture, b) Guiding the mixture past at least one electron beam, c) Separating the irradiated dose measuring devices from the treated mixture, d) Analyzing the irradiated measuring film, and e) Determining the applied radiation dose.

12. The method according to claim 11, wherein before analyzing the irradiated measuring film), the irradiated measuring film is removed from the base body.

13. The method according to claim 11 or 12, wherein the number of dose measuring devices (step a) added per kg of particulate material is 4 to 50, preferably 8 to 30, particularly preferably 8 to 20.

14. The method according to claim 11, wherein a transfer factor is determined preferably by means of a Monte Carlo simulation for the determined to the actual value.

Description

[0051] The invention is explained in detail hereinafter with reference to an exemplary embodiment and several drawings. In the figures:

[0052] FIG. 1: shows a first perspective view of a device for pasteurizing and/or sterilizing particulate material;

[0053] FIG. 2: shows a front view of the device shown in FIG. 1 with opened doors;

[0054] FIG. 3: shows a schematic side view of a part of the device shown in FIGS. 1 and 2;

[0055] FIG. 4: shows a front view of a dose measuring device according to the invention;

[0056] FIG. 5: shows a side view of a base body of a dose measuring device according to the invention;

[0057] FIG. 6: shows a top view of a treated mixture of particulate material and several dose measuring devices;

[0058] FIGS. 7-10: show views of the dose measuring device before use in various assembly states;

[0059] FIGS. 11-13: show views of the dose measuring device after use in various assembly states.

[0060] The device 10 shown in FIGS. 1 and 2 is provided for the pasteurization and/or sterilization of particulate material such as a spice, sesame, almonds or shelled pistachios. The device 10 contains an outer housing 40, a material inlet 43, a material outlet 44 and a material guide channel 41 in which the material can be guided from the material inlet 43 along a material guiding direction R through the device 10 to the material outlet 44. Located outside the outer housing 44 of the device 10 are an electrical frame 140 with an electric cabinet 141 and two generators 142 for supplying the subsequently described electron sources 20 and a pedestal 143. A mixing device 46 is provided by means of which the material 30 and several dose measuring devices 51 can be mixed before treatment of the same. The mixing device 46 can be part of the device 10 oras shown here as an examplea separate device.

[0061] The device 10 furthermore contains according to FIG. 2 a metering device not shown here by means of which the mixture can be metered onto a first vibration surface 14 which can be excited to vibrate. With the aid of this first vibration surface 14, the throughput of the mixture and therefore of the material can be controlled and a pre-separation can also take place already. Downstream of the first vibration surface 14, the device 10 contains a second vibration surface 11 which can be excited to vibrate. By this means the mixture can be conveyed further downstream and separated. Located downstream of the vibration surface 11 is an inclined sliding surface 16.

[0062] Even further downstream, the device 10 contains a treatment zone 19. There the mixture of the material 30 and the plurality of dose measuring devices 51 are pasteurized and/or sterilized in a free-falling manner by means of an electron beam which is generated by two mutually opposite electron sources 20.

[0063] FIG. 3 shows schematically a part of the device 10 according to the invention.

[0064] In the case of spices (e.g. peppercorns) the mixture advantageously moves at a speed of 3.0 m/s through the treatment zone 19. This speed can be adjusted by the length and the angle of inclination of the sliding surface 16. The electrons of the electron beam have an energy which lies in the range from 80 keV to 300 keV, for example, 250 keV. In the treatment zone 19, the electron beam has an average current density which lies in the range from 10.sup.15 s.sup.1.Math.cm.sup.2 to 2.77.10.sup.15 s.sup.1.Math.cm.sup.2. The mixture is exposed to the electron beam for a treatment time which can lie in the range from 15 ms to 25 ms and can, for example be 15 ms. As a result, the mixture or the material 30 is exposed to a radiation dose which can lie in the range from 1 kGy to 30 kGy and can, for example, be 12 kGy.

[0065] The dose measuring devices 51 distributed in the treated particulate material 30 (here peppercorns) can be seen in FIG. 6.

[0066] The dose measuring device 51 according to the invention for the measurement of a radiation dose or parts thereof are shown in FIGS. 4 to 5 and 7 to 13 which show various states of the dose measuring device 51. The dose measuring device 51 and its use in connection with the pasteurization and/or sterilization of peppercorns as particulate material 30 is described hereinafter.

[0067] The dose measuring device 51 has a radiation-sensitive measuring film 62 and a base body 52.

[0068] The base body 52 has a cylindrical section 53 and at both ends thereof respectively one guide section 54 which project radially outwards beyond the cylindrical section 53. The measuring film 62 is wound onto the base body 52 at least in some areas in the region of the cylindrical section 53 and surrounds this with several layers.

[0069] In the present exemplary embodiment the ratio is approximately 1.2 to 1.6:1.0 between the external diameter D2 of the guide sections 54 and the external diameter D1 of the cylindrical section 53. The external diameter D1 of the cylindrical section 53 here is 3 mm, which approximately corresponds to the average diameter of a peppercorn. The ratio of the total length L of the base body 52 and the length L1 of the cylindrical section 53 is about 1.05 to 1.2:1.0. The length L1 of the cylindrical section 53 here is approximately more than 20 mm.

[0070] For the preparation of the dose measuring device 51 reference is essentially made hereinafter to FIGS. 7 to 10.

[0071] The base body 52 is fabricated from carbon-based material, preferably from a polymer, for example, in a 3D printing process. The material of the base body has a density, e.g., of about 1.05 g/cm3 which largely corresponds to the density, e.g., of about 0.85 g/cm3 of the particulate material 30 to be treated (here the density of a peppercorn). The chemical structure of the material of the base body largely corresponds to the chemical structure of the particulate material 30 to be treated (here the chemical structure of a peppercorn).

[0072] Before using the base body 52, this is tested for possible damage and if necessary, undesired projections are removed from the fabrication.

[0073] The measuring film 12 is optionally cut to the desired size. The width Bm of the measuring film 62 is advantageously selected in such a manner that the measuring film 62 comes to rest between the two guide sections 54 during winding onto the base body 52. The length Lm of the measuring film 62 is selected according to the desired number of windings or layers of the measuring film 62 which the dose measuring device 51 should ultimately have.

[0074] The radiation-sensitive measuring film 62 has a thickness of up to 200 m, preferably of 10-50 m. In the present exemplary embodiment, a Ris B3 Radiochromic Dosimeter Film made by Tesa, Hamburg is used as measuring film 62.

[0075] For the arrangement or for fixing of the measuring film 62 on the base body 52, a first end of the measuring film 62 can be provided by means of an adhesive strip as a first fixing means 66 (FIG. 9). Alternatively the measuring film 62 is wound onto the base body 52 without fixing.

[0076] The number of windings of the measuring film 62 on the base body 52 is 1 to 20, preferably 2 to 10 and particularly preferably 3 to 6. The number of windings is, for example, dependent on the degree in which the accomplished penetration of the radiation into the material 30 is to be detected. With a view to the resulting results and the use of measuring film 62, for example, a number of three windings has proved advantageous.

[0077] The free-lying regions of the second end 64 of the measuring film 62 are here fixed with two fine adhesive strips as second fixing means 67 (FIG. 10).

[0078] Advantageously the measuring film 62 is arranged between the windings on the base body 52 largely without air bubble inclusions or bends. If air bubble inclusions cannot be prevented, these should be kept as small as possible in order not to influence too strongly the evaluation of an irradiated dose measuring device 51.

[0079] The prepared dose measuring device 51 should be stored dry and in the dark, advantageously at room temperature before it is used.

[0080] A plurality of prepared dose measuring devices 51 are mixed with the particulate material 30 to be treated. Per kg of particulate material 30 to be treated, 4 to 50 dose measuring devices 51, preferably 8 to 30 dose measuring devices 51, particularly preferably 8 to 20 dose measuring devices 51 are added.

[0081] The mixture is passed by the electron beam which was generated by the electron sources 20, wherein the particulate material 30 as also the dose measuring devices 51 distributed in this material 30 are irradiated.

[0082] The dose measuring devices 51 (see FIG. 6) located in the treated mixture are then separated from the same.

[0083] For the following analysis the irradiated measuring films 62 are advantageously removed or the irradiated dose measuring devices 51 are dismantled (see FIGS. 11 to 13).

[0084] By means of a suitable tool 68, e.g. tweezers, the two fixing means 67 are removed (FIG. 12) and then the irradiated measuring film 62 is unwound (FIG. 13).

[0085] The base body 52 can be fitted with a new measuring film for a further use (see FIGS. 7 to 10).

[0086] The introduced radiation dose is then determined by means of a suitable dosimetry scanner (not shown here). In order to taken into account system-dependent or material-dependent inaccuracies between the measured value determined in the analysis and the actual value of the radiation dose, a transfer factor is advantageously determined. The transfer factor is determined, for example, by means of a Monte Carlo simulation.

REFERENCE LIST

[0087] 10 Device [0088] 11 2nd vibration surface [0089] 14 1st vibration surface [0090] 16 Sliding surface [0091] 19 Treatment zone [0092] 20 Electron source [0093] 30 Particulate material [0094] 41 Material guiding channel [0095] 43 Material inlet [0096] 44 Material outlet [0097] 46 Mixing device [0098] 51 Dose measuring device [0099] 52 Base body [0100] 53 Cylindrical section of 52 [0101] 54 Guide section [0102] 62 Radiation-sensitive measuring film [0103] 63 1st end of 62 [0104] 64 2nd end of 62 [0105] 66 1st fixing means [0106] 67 2nd fixing means [0107] 68 Tool [0108] 141 Electric cabinet [0109] 142 Generator [0110] 143 Pedestal [0111] R Material guiding direction [0112] L Length of dose measuring device 51 [0113] L1 Length of cylindrical section 53 [0114] D1 Diameter of cylindrical section 53 [0115] D2 Diameter of guide section 54 [0116] Lm Length of measuring film 62 [0117] Bm Width of measuring film 62