Radiation monitor

Abstract

To provide a radiation monitor capable of measuring a radioactive substance with high accuracy by suppressing the influence of a contamination component.SOLUTION: A radiation monitor includes a flow path section through which a detection target liquid containing a radionuclide flows, a phosphor layer that emits photons by interaction with radiation emitted by the radionuclide, and a β-ray transmission layer that is arranged between the phosphor layer and the flow path section and attenuates and absorbs the radiation emitted by the radionuclide in the flow path section.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a radiation monitor. [Background technology]

[0002] Radiation measurement devices using, for example, a liquid scintillator, an ionization chamber, or a solid scintillator are used to measure radiation from nuclides in liquids such as water. For example, a radiation monitor has been proposed in which a sampling container through which a liquid to be detected passes is provided between two opposing flat solid scintillators (see, for example, Patent Document 1). In this radiation monitor, the solid scintillator is excited by radiation emitted from the liquid to be detected, and the photons generated by the solid scintillator are measured to determine the concentration of the radioactive material. Such a radiation monitor using a solid scintillator is expected to be a method capable of measuring radionuclides in liquids such as water online. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-178336 Summary of the Invention [Problem to be solved by the invention]

[0004] It is important for a radiation monitor to have high radiation detection sensitivity. The radiation monitor described in Patent Document 1 uses a large flat detector to increase the contact area with the water to be measured and improve sensitivity. However, in the radiation monitor described in Patent Document 1, the container surface area in contact with the water increases, increasing the impact of radioactive materials (contamination) adhering to the container surface. The occurrence of contamination is unavoidable as long as a liquid containing radioactive materials is passed through the monitor. When contamination occurs, it becomes impossible to distinguish between signals due to contaminant components and signals from radioactive materials in the water, making it impossible to accurately measure the concentration of radioactive materials.

[0005] In order to solve the above-mentioned problems, the present invention provides a radiation monitor that can suppress the influence of contaminants and measure radioactive materials with high accuracy.

[0006] The above and other objects of the present invention and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0007] The radiation monitor of the present invention comprises a flow path section through which a detectable liquid containing a radionuclide flows, a phosphor layer that emits photons through interaction with radiation emitted by the radionuclide, and a beta-ray transparent layer that is disposed between the phosphor layer and the flow path section and attenuates and absorbs radiation emitted by the radionuclide in the flow path section. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a radiation monitor that can suppress the influence of contaminant components and measure radioactive materials with high accuracy.

[0009] Problems, configurations, and effects other than those described above will become clear from the following description of the embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view of a radiation monitor according to a first embodiment. [Figure 2] 2 is a cross-sectional view of the radiation monitor shown in FIG. 1 taken along line AA. [Figure 3] 2 is a cross-sectional view of the radiation monitor shown in FIG. 1 taken along line BB. [Figure 4] FIG. 1 is a block diagram of a radiation monitor according to a first embodiment. [Figure 5] FIG. 2 is a block diagram of a first modified example of the radiation monitor of the first embodiment. [Figure 6] FIG. 10 is a block diagram of a second modified example of the radiation monitor of the first embodiment. [Figure 7]FIG. 10 is a block diagram of a third modified example of the radiation monitor of the first embodiment. [Figure 8] FIG. 10 is a block diagram of a fourth modified example of the radiation monitor of the first embodiment. [Figure 9] FIG. 10 is a block diagram of a fifth modified example of the radiation monitor of the first embodiment. [Figure 10] FIG. 10 is a block diagram of a sixth modified example of the radiation monitor of the first embodiment. [Figure 11] FIG. 10 is a block diagram of a seventh modified example of the radiation monitor of the first embodiment. [Figure 12] FIG. 13 is a block diagram of an eighth modified example of the radiation monitor of the first embodiment. [Figure 13] FIG. 13 is a block diagram of a ninth modified example of the radiation monitor of the first embodiment. [Figure 14] FIG. 10 is a perspective view of a radiation monitor according to a second embodiment. [Figure 15] 15 is a cross-sectional view of the radiation monitor shown in FIG. 14 taken along line AA. [Figure 16] 15 is a cross-sectional view of the radiation monitor shown in FIG. 14 taken along the line BB. [Figure 17] FIG. 10 is a block diagram of a radiation monitor according to a second embodiment. [Figure 18] FIG. 10 is a block diagram of a first modified example of the radiation monitor of the second embodiment. [Figure 19] FIG. 10 is a block diagram of a second modified example of the radiation monitor of the second embodiment. [Figure 20] FIG. 10 is a block diagram of a third modified example of the radiation monitor of the second embodiment. [Figure 21] FIG. 10 is a block diagram of a fourth modified example of the radiation monitor of the second embodiment. [Figure 22] FIG. 10 is a block diagram of a fifth modified example of the radiation monitor of the second embodiment. [Figure 23] FIG. 10 is a block diagram of a sixth modified example of the radiation monitor of the second embodiment. [Figure 24] FIG. 10 is a block diagram of a seventh modified example of the radiation monitor of the second embodiment. [Figure 25] FIG. 11 is a block diagram of an eighth modified example of the radiation monitor of the second embodiment. [Figure 26] FIG. 13 is a block diagram of a ninth modified example of the radiation monitor of the second embodiment. [Figure 27] FIG. 10 is a block diagram of a radiation monitor according to a third embodiment. [Figure 28] FIG. 10 is a block diagram of a modified example of the radiation monitor of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] An example of a radiation monitor according to an embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the following example. In each of the drawings described below, common members are given the same reference numerals. Furthermore, in the drawings used in this specification, identical or corresponding components are given the same reference numerals, and repeated explanations of these components may be omitted.

[0012] The explanation will be given in the following order. 1. Configuration of Radiation Monitor (First Embodiment) 2. Configuration of Radiation Monitor (Second Embodiment) 3. Configuration of Radiation Monitor (Third Embodiment)

[0013] 1. Configuration of Radiation Monitor (First Embodiment) [Radiation monitor configuration] A first embodiment of a radiation monitor will be described. Fig. 1 shows a schematic configuration (perspective view) of a radiation monitor 1 according to the first embodiment. Fig. 2 shows a cross-sectional view of the radiation monitor 1 shown in Fig. 1 taken along line AA, and Fig. 3 shows a cross-sectional view of the radiation monitor 1 taken along line BB. As shown in Fig. 1, the radiation monitor 1 includes a radiation detection unit 2 and a flow path unit 5. The radiation detection unit 2 also includes a phosphor layer 3 and a β-ray transmission layer 4. The radiation detection unit 2 and flow path unit 5 that constitute the radiation monitor 1, and the phosphor layer 3 and β-ray transmission layer 4 that constitute the radiation detection unit 2 will be described below.

[0014] [Radiation detection unit] As shown in Figures 1, 2, and 3, the radiation detection unit 2 is composed of a phosphor layer 3 and a β-ray transmission layer 4. A flow path section 5 is disposed in contact with the β-ray transmission layer 4. The flow path section 5 is formed within the phosphor layer 3, and a detection target liquid 6 flows through the flow path section 5. The phosphor layer 3 interacts with β-rays emitted from radioactive materials within the flow path section 5, thereby emitting photons. The radiation monitor 1 has a flow path section 5 in a phosphor layer 3 that constitutes the radiation detection section 2. Furthermore, the radiation monitor 20 has a β-ray transmitting layer 4 on the wall surface of the flow path section 5. That is, in the radiation monitor 20, the β-ray transmitting layer 4 is interposed between the detection target liquid 6 and the phosphor layer 3 in the flow path section 5.

[0015] Furthermore, in the radiation monitor 1, the sidewalls of the flow path section 5 are affected by the adhesion of radioactive materials, so-called contamination. The radiation monitor 1 is, for example, a radiation monitor capable of continuously measuring the concentration of a radioactive nuclide 7 in the detectable liquid 6 online, and selectively detects radiation from the radioactive nuclide contained in the detectable liquid 6 flowing through the flow path section 5 and radiation from contaminant components adhered to the surface of the flow path section 5. Specifically, radiation from the radioactive nuclide contained in the detectable liquid 6 flowing through the flow path section 5 is attenuated and absorbed in the β-ray transmission layer 4. Then, radiation from the radioactive nuclide of the contaminant components passes through the β-ray transmission layer 4. As a result, radiation from the radioactive nuclide contained in the detectable liquid 6 does not pass through the phosphor layer 3, and only radiation from the radioactive nuclide of the contaminant components is detected by the phosphor layer 3.

[0016] [Phosphor layer] The phosphor layer 3 is made of a solid composition in order to form the flow path portion 5 therein. The phosphor layer 3 is not particularly limited as long as it is a composition that exhibits luminescence, and examples include photoluminescence caused by light such as ultraviolet light, radioluminescence caused by radiation, cathode luminescence caused by an electron beam, electroluminescence caused by an electric field, and chemiluminescence caused by a chemical reaction. Specifically, the phosphor layer 3 is made of, for example, NaI, CsI, LiI, SrI2, Bi4Ge3O as a base material. 12 , Bi4Si3O 12, CdWO4, PbWO4, ZnS, CaF2, LuAG, LuAP, Lu2O3, Y3Al5O 12 , YAlO3, Lu2SiO5, LYSO, Y2SiO5, Gd2SiO5, BaF2, CeF3, CeBr3, CsF, LiF, Gd2O2S, LaBr3, CeBr3, Gd3Al2Ga3O 12 Examples of such materials include light-transmitting materials such as Cs2LiYCl6, Cs2HfI6, ScTaO4, LaTaO4, LuTaO4, GdTaO4, YTaO4, InBO3, Y2O2S, ZnSiO4, and sialon phosphors, as well as light-transmitting materials containing rare earth elements such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, and elements, ions, and fluorescent materials such as Tl, Na, Ag, W, Cu, Al, Au, Mn, and CO3. More specifically, examples of such materials include InBO3:Tb, InBO3:Eu, ZnS:Cu, ZnS:Al, ZnS:Au, Y2O2S:Eu, Y2O2S:Tb, and ZnSiO4:Mn.

[0017] The valence of the element ions contained in the phosphor layer 3 is not particularly limited as long as it can be used for luminescence, and can be, for example, monovalent, divalent, trivalent, tetravalent, etc. Furthermore, for example, organic phosphors such as complexes, organic compounds, plastic scintillators, etc. can also be used as the phosphor layer 3.

[0018] (β-ray transparent layer) The radiation monitor 1 shown in Figures 2 and 3 includes a β-ray transmitting layer 4 between the phosphor layer 3 and the flow path section 5 in the radiation detection section 2. That is, in the radiation monitor 1, the β-ray transmitting layer 4 is interposed between the flow path section 5 and the phosphor layer 3. That is, the β-ray transmitting layer 4 is interposed between the detection target liquid 6 and the phosphor layer 3. The β-ray transparent layer 4 attenuates and absorbs the radiation 9. There are no particular limitations on the β-ray transparent layer 4, as long as it interacts with the radiation emitted from the radioactive material. The β-ray transparent layer 4 can be made of, for example, air (gas), wood, resin, water, glass, metal, etc. The β-ray transmission layer 4 may also utilize a phosphor that emits photons upon interaction with the radiation 9 and the radiation 15. When a phosphor is used as the β-ray transmission layer 4, the same phosphor as that used for the phosphor layer 3 described above can be used. When a phosphor is used as the β-ray transmission layer 4, the same phosphor as that used for the phosphor layer 3 described above may be powdered or microparticulated and dispersed in a solid such as resin or glass. In this case, the size, shape, and dispersion amount of the phosphor powder or microparticles are set to preferred values ​​depending on the desired fluorescent characteristics and physical properties such as the transmittance of β-rays.

[0019] The range of radiation is affected by the density of the material that constitutes the β ray transmitting layer 4. The lower the density of the material that transmits the radiation, the greater the range of radiation. For this reason, the material that constitutes the β ray transmitting layer 4 is not particularly limited, but for example, 3 The density of the β-ray transmitting layer 4 is preferably 1.0 g / cm or less. 3 By satisfying the following conditions, the range of radiation in the β-ray transmission layer 4 can be made equal to or longer than that in water. The β-ray transmission layer 4 may be made of the above-mentioned air (gas), wood, resin, water, glass, metal, etc. as a base, and the density may be adjusted by mixing additives. For example, when a gas is used as the β-ray transmission layer 4, the desired density may be adjusted by adjusting the composition, pressure, etc. of the gas. Furthermore, when a resin is used as the β-ray transmission layer 4, the density may be adjusted by the composition of the resin or additives added to the resin.

[0020] Furthermore, the thickness of the β-ray transmission layer 4 is preferably set to be equal to or less than the range of radiation emitted from the radioactive nuclide to be measured. Because the range of radiation in the β-ray transmission layer 4 is affected by the density of the material constituting the β-ray transmission layer 4, the thickness of the β-ray transmission layer 4 is preferably set to be equal to or less than the range of radiation at that density. If the thickness of the β-ray transmission layer 4 exceeds the range of radiation, it becomes difficult to detect radiation with the phosphor layer 3. Furthermore, the thickness of the β-ray transmission layer 4 is preferably 70% to 95% of the range of radiation, and more preferably 80% to 90%. As the thickness of the β-ray transmission layer 4 approaches the range of radiation, the number of radiation detection counts with the phosphor layer 3 decreases, resulting in a decrease in detection sensitivity. Furthermore, if the thickness of the β-ray transmission layer 4 is too small, it becomes difficult to distinguish between radiation from the detection target liquid 6 and radiation from contaminants adhering to the wall surface of the flow path section 5, resulting in a decrease in the accuracy of detecting radiation from the contaminants.

[0021] [Flow path] The radiation detection unit 2 includes two bonded phosphor layers 3. Each phosphor layer 3 has a symmetrical semicircular groove on one main surface. The phosphor layers 3 are bonded together with the positions of the semicircular grooves aligned. This forms a tubular cavity inside the phosphor layer 3. This tubular cavity has openings 53, 54 at two locations: one at a given position on the surface of the phosphor layer 3 and another at another position on the surface. The tubular cavity communicates with the openings 53, 54. The communicating cavity inside the phosphor layer 3 is a flow path 5 through which a detectable liquid 6 containing radioactive nuclides flows. Therefore, the radiation detection unit 2 has a flow path 5 formed by a tubular cavity formed inside the phosphor layer 3.

[0022] A detection target liquid 6, indicated by an arrow in Fig. 2, is supplied from the outside to the flow path section 5. In the configuration shown in Figs. 1 and 2, the flow path section 5 has openings 53 and 54 on opposing surfaces on which the light detection section 10 is not disposed. The detection target liquid 6 flows into the flow path section 5 from one opening 53 (inlet), passes through the flow path section 5, and is discharged from the other opening 54 (outlet). 1, the phosphor layer 3 is formed in the shape of a rectangular parallelepiped, for example. The shape of the phosphor layer 3 is not particularly limited, and may be any shape that allows the flow path section 5 to be formed therein and allows the light detection section 10 to detect photons.

[0023] The flow path section 5 is a tubular hollow section formed within the phosphor layer 3, and is therefore surrounded by the phosphor layer 3. That is, the flow path section 5 has a portion whose entire periphery is covered by the phosphor layer 3 in a cross section perpendicular to the flow direction of the detection liquid 6. Although the radiation monitor 1 shown in FIG. 1 has the entire flow path section 5 covered by the phosphor layer 3, this is not limited thereto. It is sufficient that at least a portion of the periphery of the flow path section 5 is covered by the phosphor layer 3. Therefore, the flow path section 5 may have a portion that is not covered by the phosphor layer 3, or a portion of the periphery that is not covered by the phosphor layer 3.

[0024] The flow path section 5 has a straight flow path section 51 whose flow portion is formed in a straight line and a curved flow path section 52 whose flow portion is formed in a curved line. The flow path section 5 is connected from the inlet to the outlet by a combination of the straight flow path section 51 and the curved flow path section 52. In the configuration shown in FIGS. 2 and 3, the flow path section 5 has three straight flow path sections 51 whose flow portion is formed in a straight line and two curved flow path sections 52 whose flow portion is formed in a curved line. In the flow path section 5, the straight flow path sections 51 are connected by the curved flow path sections 52. The flow path section 5 is extended in two dimensions by connecting the straight flow path sections 51 extending in the x-axis direction with the curved flow path sections 52 extending in the y-axis direction. In other words, the two curved flow path sections 52 form two turning portions in the flow path section 5.

[0025] The shape of the flow path section 5 is not limited to this. For example, the flow path section 5 may have an inlet and an outlet formed on the same surface of the phosphor layer 3, and may be configured to be linearly connected from the inlet to the outlet. The flow path section 5 may also have a configuration in which a plurality of linear flow path sections 51 are arranged in parallel positions, a configuration in which they are arranged in a twisted position, or a configuration in which a plurality of curved flow path sections 52 form a plurality of turning sections. 1-3, the flow path section 5 is two-dimensionally arranged by the straight flow path section 51 extending in the x-axis direction and the curved flow path section 52 extending in the y-axis direction, but is not limited to this shape. For example, the flow path section 5 may be formed by a cavity section arranged three-dimensionally in which at least one of the straight flow path section 51 and the curved flow path section 52 extends in the z-axis direction. In this way, it is preferable that the flow path section 5 is connected linearly or non-linearly from the inlet to the outlet by at least one of the straight flow path section 51 and the curved flow path section 52 . The radiation monitor 1 may also be configured to include flat solid scintillators arranged opposite each other, with a flow path formed between the flat plates through which the liquid to be detected flows.

[0026] The cross-sectional shape of the flow path section 5 is not particularly limited as long as it allows the detection liquid 6 to pass through it, but for example, by making the inner diameter of the flow path section 5 1.1 cm or less, the attenuation of beta rays in water can be reduced and the detection sensitivity of beta rays can be improved. 1 and 3 has a cylindrical cross section, there is no particular limitation on the cross-sectional shape of the flow path section 5. The cross-sectional shape of the flow path section 5 may be an ellipse or a polygonal shape such as a rectangle or a square. Furthermore, it is preferable that the inner diameter of the flow path section 5 is a constant value. It is also preferable that the cross-sectional shape of the flow path section 5 does not change. By not changing the inner diameter or cross-sectional shape, the radiation monitor 1 can stabilize the detection sensitivity.

[0027] In the radiation monitor 1, when the y-axis direction is the vertical direction, the detectable liquid 6 is supplied from the opening 53 at the bottom (below the y-axis) of the flow path section 5 to the opening 54 at the top (above the y-axis) as shown by the arrow in FIG. 2 . By supplying the detectable liquid 6 in this direction, the flow path section 5 can be filled with the detectable liquid 6 without leaving any cavities inside. As a result, the area where the phosphor layer 3 and the detectable liquid 6 are adjacent can be increased. The flow direction of the detectable liquid 6 is not particularly limited. For example, when the y-axis direction is the vertical direction, the detectable liquid 6 may be supplied from the opening 54 at the top (above the y-axis) of the flow path section 5 to the opening 53 at the bottom (below the y-axis). This supply direction eliminates the need for a pressure device such as a pump to supply the detectable liquid 6, thereby eliminating mechanical vibration noise caused by the pressure device and improving measurement accuracy.

[0028] (Manufacturing method of radiation detection unit) The phosphor layer 3 can be manufactured using, for example, a floating zone method, a Czochralski method (pulling-up method), a micro-pulling-down method, a Bridgman method, a Verneuil method, organic synthesis, or the like. The flow path section 5 can be manufactured by applying a method capable of micro-machining the phosphor layer 3. For example, semicircular grooves are formed on the surface of the phosphor layer 3 by machining, chemical reaction, or the like. Then, the machined surfaces of the phosphor layers 3 with the grooves formed thereon are bonded together.

[0029] Furthermore, when the β-ray transmission layer 4 is formed between the phosphor layer 3 and the flow path section 5, the material for the β-ray transmission layer 4 is filled into the semicircular grooves formed in the phosphor layer 3 described above and solidified. Further, semicircular grooves are formed in the solidified β-ray transmission layer 4 using machining, chemical reaction, or the like. Then, the processed surfaces of the phosphor layer 3 with the grooves formed in the β-ray transmission layer 4 and the β-ray transmission layer 4 are bonded together. When the β-ray transmission layer 4 is formed from a phosphor, the same manufacturing method as for the phosphor layer 3 described above can be applied. When a powdered or microparticulated phosphor is dispersed in the β-ray transmission layer 4, the same phosphor as that for the phosphor layer 3 is powdered or microparticulated and dispersed in the material constituting the β-ray transmission layer 4 described above, filled, and solidified.

[0030] This allows the manufacture of a radiation detection unit 2 in which a flow path portion 5 is formed in the phosphor layer 3 and the β-ray transmission layer 4. Furthermore, if non-linear processing is difficult due to the material of the solid phosphor or the β-ray transmission layer 4, the difficulty of processing can be relatively reduced by forming only the difficult-to-process portions from a material other than phosphor. In this way, the radiation detection unit 2 may be formed by combining the phosphor layer 3 and the β-ray transmission layer 4 with materials other than these. As an example of the folded shape, the folded shape can be described as a shape having a flow path whose dimension is longer than the sum of the vertical and horizontal dimensions of the processed surface of the phosphor layer 3. This allows the photodetector to be placed near the light source, thereby improving detection efficiency.

[0031] [Light detection section] The light detection unit 10 is disposed adjacent to the phosphor layer 3 of the radiation detection unit 2. The light detection unit 10 continuously measures, for example, the radiation dose in the detection target liquid 6 in the flow path unit 5. The light detection unit 10 detects photons generated in the phosphor layer 3. The light detection unit 10 converts the photons generated in the phosphor layer 3 into an electrical pulse signal. The light detection unit 10 is not particularly limited as long as it can convert photons into an electrical pulse signal, and for example, a photomultiplier tube, a photodiode, an avalanche photodiode, an image sensor, etc. can be used. This allows the photons generated in the phosphor layer 3 to be measured as an electrical pulse signal.

[0032] [Liquid to be detected] The liquid to be detected 6 contains a nuclide that emits radiation. The nuclide is not particularly limited, but examples include Sr-90 and Y-90. The emitted radiation is not particularly limited, but examples include particle rays such as α-rays, β-rays, and neutron rays, and electromagnetic waves such as X-rays and γ-rays. Of these, the radiation detected by the radiation monitor 10 is preferably α-rays and β-rays. The liquid to be detected 6 contains the nuclide in a dissolved or dispersed state. The portion of the liquid to be detected 6 excluding the nuclide is not particularly limited as long as it is liquid, and may be, for example, treated water from a nuclear power plant, seawater, brackish water, or other aqueous solution (brine water, etc.), but may also be fresh water.

[0033] [Block diagram of radiation monitor] Next, a block diagram of the radiation monitor 1 according to the first embodiment described above is shown in FIG. 4. The radiation monitor 1 shown in FIG. 4 has a configuration in which the light detection unit 10 is omitted from the radiation monitor 1 shown in FIGS. 1 and 3. As shown in FIG. 4, the radiation monitor 1 generally includes a radiation detection unit 2 made up of a phosphor layer 3 and a β-ray transmission layer 4, and a flow path 5. A detectable liquid 6 flows through the flow path 5. Within the flow path 5, there are radioactive nuclides 7 in the detectable liquid 6 and radioactive nuclides 8 (contaminants) attached to the wall surfaces of the flow path 5. FIG. 4 illustrates radiation 9 emitted from the radioactive nuclides 7 in the detectable liquid 6 and radiation 15 emitted from the radioactive nuclides 8 attached to the wall surfaces of the flow path 5.

[0034] In the radiation monitor 1, the β-ray transmitting layer 4 is disposed between the flow path section 5 and the phosphor layer 3. The β-ray transmitting layer 4 is formed to a thickness equal to or smaller than the range of the radiation 9, 15 emitted from the radioactive nuclides 7, 8 to be measured. Therefore, radiation 15 emitted from radionuclides 8 (contaminants) attached to the wall surface of the flow path section 5 passes through the β-ray transmitting layer 4 and reaches the phosphor layer 3. The radiation 15 is then attenuated and absorbed in the phosphor layer 3. The phosphor layer 3 is excited by the radiation 15 and generates photons. On the other hand, radiation 9 emitted from radionuclides 7 in the detectable liquid 6 is attenuated and absorbed in the β-ray transmission layer 4 and does not reach the phosphor layer 3. The thickness of the β-ray transmission layer 4 is equal to or less than the range of the radiation, preferably between 80% and 90% of the range of the radiation. Therefore, a portion of the radiation 9 emitted from the radionuclides 7 in the detectable liquid 6 passes through the β-ray transmission layer 4 and reaches the phosphor layer 3. The amount of radiation 9 that passes through the β-ray transmission layer 4 and reaches the phosphor layer 3 can be adjusted by the density and thickness of the β-ray transmission layer 4, as described above. Therefore, in the phosphor layer 3, excitation and photon generation caused by the radiation 9 emitted from the radionuclides 7 in the detectable liquid 6 are limited to a certain extent. As a result, the radiation monitor 1 can suppress the influence of radiation 9 emitted from radioactive nuclides 7 in the detection liquid 6 and detect radiation 15 emitted from radioactive nuclides 8 due to contaminant components. In other words, the radiation monitor 1 can selectively detect the influence of radioactive nuclides 8 attached to the sidewall of the flow path section 5, i.e., the influence of so-called contaminant components.

[0035] [Modified example of radiation monitor] Next, modified examples of the radiation monitor according to the first embodiment will be described. In the following modified examples, explanations of the same configurations as those of the radiation monitor according to the first embodiment will be omitted. In addition, in the explanation of the modified examples, only a block diagram of the radiation monitor will be shown, and the same reference numerals will be used in the explanation of the same configurations as those in FIG. 4 above.

[0036] (Variation 1) FIG. 5 shows a block diagram of a first modified example of a radiation monitor. The radiation monitor 1A shown in FIG. 5 has the same configuration as the radiation monitor 1 shown in FIGS. 1 to 3. The radiation monitor 1A generally includes a radiation detection unit 2 made up of a phosphor layer 3 and a β-ray transmission layer 4, and a flow path unit 5. A light detection unit 10 is connected to the phosphor layer 3. The light detection unit 10 is connected to the surface of the phosphor layer 3 opposite the β-ray transmission layer 4. The light detection unit 10 converts photons generated in the phosphor layer 3 into an electric pulse signal.

[0037] In the radiation monitor 1A shown in Fig. 5, the β-ray transmission layer 4 is disposed between the flow path section 5 and the phosphor layer 3. The β-ray transmission layer 4 is formed with a thickness equal to or less than the range of radiation emitted from the radioactive nuclide to be measured. Therefore, radiation 15 emitted from radioactive nuclide 8 (contaminants) attached to the wall surface of the flow path section 5 passes through the β-ray transmission layer 4 and reaches the phosphor layer 3. On the other hand, radiation 9 emitted from the radioactive nuclide 7 in the detection liquid 6 is attenuated and absorbed in the β-ray transmission layer 4 and does not reach the phosphor layer 3. Therefore, the phosphor layer 3 is excited mainly by radiation 15 from the contaminants, generating photons. As a result, the radiation monitor 1A can measure the concentration of radionuclides 8 attached to the wall surface of the flow path section 5, i.e., the contaminants, by having the light detection section 10 measure (count) the photons emitted by the phosphor layer 3. In other words, the radiation monitor 1A can selectively detect the influence of radionuclides 8 attached to the side wall of the flow path section 5, i.e., the influence of the contaminants.

[0038] [Radiation monitor block diagram (variation 2)] Next, Fig. 6 shows a block diagram of a second modified example of the radiation monitor. The radiation monitor 20 shown in Fig. 6 generally includes a radiation detection unit 2 consisting of a phosphor layer 3 and a β-ray transmission layer 4, and a flow path unit 5. A photodetector 10 (first photodetector) is connected to the phosphor layer 3, and a photodetector 21 (second photodetector) is connected to the β-ray transmission layer 4. The photodetector 10 is connected to the surface of the phosphor layer 3 opposite the β-ray transmission layer 4. The photodetector 21 is connected to the surface of the β-ray transmission layer 4 opposite the flow path unit 5, on which the phosphor layer 3 is not formed.

[0039] The radiation monitor 20 shown in Fig. 6 includes a phosphor as the β ray transmission layer 4. The β ray transmission layer 4 contains a phosphor, and thereby emits photons through interaction with radiation 9 emitted from radioactive nuclides 7 in the detection target liquid 6. Furthermore, the β ray transmission layer 4 contains a phosphor, and therefore the light detection unit 21 emits photons through interaction with radiation 15 emitted from radioactive nuclides 8 (contaminants) attached to the wall surface of the flow path unit 5. Therefore, the light detection unit 21 detects photons generated in the β ray transmission layer 4 and converts them into an electrical pulse signal. Therefore, the radiation monitor 20 can continuously measure the dose of radiation 15 due to the contaminant components using the light detection unit 10, and can simultaneously and continuously measure the dose of radiation 15 due to the contaminant components and the dose of radiation 9 due to the detectable liquid 6 using the light detection unit 21. As a result, the radiation monitor 20 reduces the influence of radioactive nuclides adhering to the surface of the flow path section 5 by subtracting the radiation dose measured by the light detection section 10 from the radiation dose measured by the light detection section 21, and can measure the radiation from the radioactive nuclides contained in the detectable liquid 6.

[0040] [Radiation monitor block diagram (variation 3)] Next, Fig. 7 shows a block diagram of a third modified example of the radiation monitor. The radiation monitor 1C shown in Fig. 7 generally includes a radiation detection unit 2 consisting of a phosphor layer 3 and a β-ray transmission layer 4, and a flow path unit 5. A photodetector 10 is connected to the phosphor layer 3, and a photodetector 21 is connected to the β-ray transmission layer 4. The photodetector 10 is connected to a surface of the phosphor layer 3 that is perpendicular to the surface that is connected to the β-ray transmission layer 4. The photodetector 21 is connected to a surface of the β-ray transmission layer 4 that is perpendicular to the surface that is connected to the phosphor layer 3 and the flow path unit 5.

[0041] 7, the radiation monitor 1C of Modification 3 has the same characteristics and effects as the radiation monitor 20 of Modification 2. Furthermore, the radiation monitor 1C of Modification 3 has a phosphor layer 3 with a larger volume than the radiation monitor 20 of Modification 2. Therefore, the radiation monitor 1C of Modification 3 has improved radiation detection sensitivity in the phosphor layer 3.

[0042] [Radiation monitor block diagram (variation 4)] Next, a block diagram of a fourth modified example of the radiation monitor is shown in Fig. 8. The radiation monitor 1D shown in Fig. 8 generally comprises a radiation detection section 2 consisting of a phosphor layer 3 and a β-ray transmission layer 4, and a flow path section 5. A photodetection section 10 is connected to the phosphor layer 3, and a photodetection section 21 is connected to the β-ray transmission layer 4. A photon reflecting layer 11 is also formed between the phosphor layer 3 and the β-ray transmission layer 4. The photon reflecting layer 11 is not particularly limited as long as it can reflect photons, and examples that can be used include Teflon (registered trademark) tape, aluminum foil, barium sulfate, optical film, optical filter, thin film, multilayer film, phosphor, grease, powder, paint, air, bulk metal, etc.

[0043] The radiation monitor 1D of Modification 4 has the same characteristics and effects as the radiation monitor 1C of Modification 3. Furthermore, by having the photon reflecting layer 11, the radiation monitor 1D can suppress the penetration of photons generated in the phosphor layer 3 into the β-ray transmission layer 4, and the penetration of photons generated in the β-ray transmission layer 4 into the phosphor layer 3. Therefore, the radiation monitor 1D can measure only photons generated in the phosphor layer 3 with the photodetector 10, and can measure only photons generated in the β-ray transmission layer 4 with the photodetector 21. As a result, the radiation monitor 1D can improve the measurement accuracy.

[0044] [Radiation monitor block diagram (variation 5)] Next, FIG. 9 shows a block diagram of a fifth modified example of a radiation monitor. The radiation monitor 1E shown in FIG. 9 generally includes a radiation detection unit 2, which is composed of a phosphor layer 3 and a β-ray transmission layer 4, and a flow path unit 5. The radiation detection unit 2 is formed in a circular shape so as to cover the outer periphery of the flow path unit 5, which has a cylindrical cross section. That is, the β-ray transmission layer 4 is formed in a cylindrical (tubular) shape that encloses the flow path unit 5. The phosphor layer 3 is also formed to cover the entire periphery in the cross-sectional direction of the β-ray transmission layer 4 (the direction perpendicular to the flow direction of the detection liquid 6). Therefore, in the radiation monitor 1E, the entire periphery in the cross-sectional direction of the flow path unit 5 is covered by the phosphor layer 3 with the β-ray transmission layer 4 interposed therebetween. The configurations of the phosphor layer 3, β-ray transmission layer 4, and flow path unit 5 are the same as those of the radiation monitor 1 shown in FIGS. 1 to 3 described above.

[0045] In addition, photodetector 10 and photodetector 21 are connected to phosphor layer 3. Photodetector 10 and photodetector 21 detect light of different emission wavelengths, although there is no particular limitation. For example, photodetector 10 detects light from phosphor layer 3, and photodetector 21 detects light from β-ray transmission layer 4. In this case, phosphor layer 3 and β-ray transmission layer 4 must each generate light of different wavelengths. Then, photodetector 10 and photodetector 21 detect light according to the emission wavelength of phosphor layer 3 and the emission wavelength of β-ray transmission layer 4, respectively.

[0046] In order to generate light of different wavelengths in the phosphor layer 3 and the β-ray transmission layer 4, it is preferable to use different types of phosphors for the phosphor layer 3 and the β-ray transmission layer 4. For example, it is preferable that either the phosphor layer 3 or the β-ray transmission layer 4 contains a trivalent rare earth element as a phosphor. For example, it is preferable that both the phosphor layer 3 and the β-ray transmission layer 4 contain a trivalent rare earth element, and that the phosphor layer 3 and the β-ray transmission layer 4 contain different trivalent rare earth elements that cause them to generate light of different wavelengths. It is also preferable that either the phosphor layer 3 or the β-ray transmission layer 4 contains a trivalent rare earth element as a phosphor, and the other is composed of a phosphor other than a trivalent rare earth element. Phosphors containing trivalent rare earth elements tend to have narrower emission wavelength peaks than other phosphors. Therefore, by using trivalent rare earth elements in the phosphor layer 3 and the β-ray transmitting layer 4, the emission from the phosphor layer 3 and the emission from the β-ray transmitting layer 4 can be accurately distinguished and detected based on the emission wavelength.

[0047] Therefore, by applying phosphors with different emission wavelengths to the phosphor layer 3 and the β-ray transmitting layer 4, the radiation monitor 1E can optically distinguish between the radioactive nuclide 7 and the radioactive nuclide 8. As a result, the radiation monitor 1E can continuously measure the dose of radiation 15 due to the contaminant components using the photodetector 10, and can simultaneously and continuously measure the doses of radiation 15 due to the contaminant components and radiation 9 due to the detectable liquid 6 using the photodetector 21. Furthermore, the radiation monitor 1E has an increased contact area between the flow path section 5 and the β-ray transmitting layer 4. This allows the radiation monitor 1E to improve its β-ray detection sensitivity.

[0048] [Radiation monitor block diagram (variation 6)] Next, FIG. 10 shows a block diagram of a sixth modified example of a radiation monitor. The radiation monitor 1F shown in FIG. 10 generally includes a radiation detection unit 2 composed of a phosphor layer 3 and a β-ray transmission layer 4, and a flow path unit 5. The radiation detection unit 2 is formed in a circular shape so as to cover the outer periphery of the flow path unit 5, which has a cylindrical cross section. That is, the β-ray transmission layer 4 is formed in a cylindrical (tubular) shape so as to cover the outer periphery on one side of the flow path unit 5. The phosphor layer 3 is also formed so as to cover the entire periphery in the cross-sectional direction of the flow path unit 5 and the β-ray transmission layer 4. Therefore, in the radiation monitor 1E, the flow path unit 5 is covered by the phosphor layer 3 over half its circumference in the cross-sectional direction, with the β-ray transmission layer 4 interposed therebetween. The half of the flow path unit 5 on which the β-ray transmission layer 4 is not formed is directly covered by the phosphor layer 3.

[0049] In addition, a light detection unit 10 (first light detection unit) and a light detection unit 22 (second light detection unit) are connected to the phosphor layer 3. The light detection unit 10 is formed on the side where the β-ray transmission layer 4 is interposed between the flow path unit 5 and the phosphor layer 3. The light detection unit 22 is formed on the side where the β-ray transmission layer 4 is not interposed between the flow path unit 5 and the phosphor layer 3. Therefore, the light detection unit 10 mainly detects the luminescence of the phosphor layer 3 due to radiation 15 from radioactive nuclides 8, which are contaminants, that have transmitted through the β-ray transmission layer 4. In addition, since the β-ray transmission layer 4 is not interposed between the flow path unit 5 and the phosphor layer 3, the light detection unit 22 detects the luminescence of the phosphor layer 3 due to both radiation 15 from the radioactive nuclides 8, which are contaminants, and radiation 9 from the radioactive nuclides 7 in the detection liquid 6.

[0050] Therefore, the radiation monitor 1F can continuously measure the dose of radiation 15 due to the contaminant components using the light detection unit 10, and can simultaneously and continuously measure the dose of radiation 15 due to the contaminant components and the dose of radiation 9 due to the detectable liquid 6 using the light detection unit 22. Furthermore, the radiation monitor 1F can reduce the position dependency of contamination in the flow path section 5 by forming the β-ray transmitting layer 4 only on one side between the flow path section 5 and the phosphor layer 3. This allows the radiation monitor 1F to improve measurement accuracy.

[0051] [Radiation monitor block diagram (variation 7)] Next, a block diagram of a seventh modified example of the radiation monitor is shown in FIG. 11. The radiation monitor 1G shown in FIG. 11 generally includes a first detection unit 2a in which a radiation detection unit 2 made of a phosphor layer 3 and a β-ray transmission layer 4 includes a flow path portion 5, and a second detection unit 2b that includes only the phosphor layer 3 and the flow path portion 5. The first detection unit 2a has the same configuration as the radiation monitor 1E of the fifth modified example shown in FIG. 9 described above. The second detection unit 2b has the same configuration as the radiation monitor 1E of the fifth modified example shown in FIG. 9 described above, except that the β-ray transmission layer 4 is removed. Therefore, in the radiation monitor 1G, the flow path portion 5 and the phosphor layer 3 are in direct contact with each other in the second detection unit 2b.

[0052] 11, the radiation monitor may include a plurality of phosphor layers 3 and a plurality of flow path sections 5. In this case, the radiation monitor preferably includes the same number of phosphor layers 3 as the number of flow path sections 5, corresponding to the plurality of flow path sections 5. Furthermore, a light detection unit 10 is connected to the phosphor layer 3 of the first detection unit 2a. A light detection unit 22 is connected to the phosphor layer 3 of the second detection unit 2b. Therefore, the light detection unit 10 mainly detects luminescence of the phosphor layer 3 due to radiation 15 from radioactive nuclides 8, which are contaminants, that have transmitted through the β-ray transmission layer 4. Furthermore, since the β-ray transmission layer 4 is not interposed between the flow path unit 5 and the phosphor layer 3, the light detection unit 22 detects luminescence of the phosphor layer 3 due to both radiation 15 from the radioactive nuclides 8, which are contaminants, and radiation 9 from the radioactive nuclides 7 in the detection liquid 6.

[0053] Therefore, the radiation monitor 1G continuously measures the dose of radiation 15 due to contaminants using the light detection unit 10, and can simultaneously and continuously measure the dose of radiation 15 due to contaminants and the dose of radiation 9 due to the detectable liquid 6 using the light detection unit 22. Furthermore, in the radiation monitor 1G, the light detection unit 22 detects the radiation 9 and 15 from the radioactive nuclides 7 and 8 that are not affected by the β-ray transmitting layer 4. This allows the radiation monitor 1G to improve measurement accuracy.

[0054] [Radiation monitor block diagram (variation 8)] Next, Fig. 12 shows a block diagram of a radiation monitor according to Modification 8. The radiation monitor 1H shown in Fig. 12 is the same as the radiation monitor 1G according to Modification 7 shown in Fig. 11 above, except that a photon reflecting layer 11 is formed between the phosphor layer 3 of the first detecting unit 2a and the phosphor layer 3 of the second detecting unit 2b. Except for the configuration related to the photon reflecting layer 11, the radiation monitor 1H has the same configuration as the radiation monitor 1G according to Modification 7 above.

[0055] The radiation monitor 1G has a photon reflecting layer 11, which can prevent photons generated in the phosphor layer 3 of the first detecting unit 2a from penetrating into the second detecting unit 2b. Furthermore, the radiation monitor 1G can prevent photons generated in the phosphor layer 3 of the second detecting unit 2b from penetrating into the first detecting unit 2a. Therefore, the radiation monitor 1G can measure only photons generated in the phosphor layer 3 of the first detecting unit 2a with the light detecting unit 10, and can measure only photons generated in the phosphor layer 3 of the second detecting unit 2b with the light detecting unit 22. As a result, the radiation monitor 1G can improve the measurement accuracy.

[0056] [Block diagram of radiation monitor (variation 9)] Next, a block diagram of a radiation monitor according to Modification 9 is shown in Fig. 13. The radiation monitor 1I shown in Fig. 13 has a first detection unit 2a and a second detection unit 2b having the same configuration as the radiation monitor 1G according to Modification 7 shown in Fig. 11 described above. Furthermore, the light detecting unit 10 and the light detecting unit 21 are connected across the phosphor layer 3 of the first detecting unit 2a and the phosphor layer 3 of the second detecting unit 2b. The light detecting unit 10 and the light detecting unit 21 are formed on different surfaces (opposite surfaces) of the phosphor layer 3. Therefore, the light detecting unit 10 and the light detecting unit 21 can detect both the light from the phosphor layer 3 and the β-ray transmitting layer 4 of the first detecting unit 2a and the light from the phosphor layer 3 of the second detecting unit 2b.

[0057] Furthermore, the light detecting units 10 and 21 detect light having different emission wavelengths, although this is not a particular limitation. For example, the light detecting unit 10 detects the emission of light from the phosphor layer 3 of the first detecting unit 2a and the phosphor layer 3 of the second detecting unit 2b. The light detecting unit 21 detects the emission of light from the β-ray transmitting layer 4 of the first detecting unit 2a. In this case, similar to the radiation monitor 1E of Modified Example 5 shown in FIG. 9 described above, phosphors having different emission wavelengths are applied to the phosphor layer 3 and the β-ray transmitting layer 4, respectively. Then, the light detecting units 10 and 21 detect light according to the emission wavelength of the phosphor layer 3 and the emission wavelength of the β-ray transmitting layer 4, respectively.

[0058] With this configuration, the radiation monitor 1G can continuously measure the dose of radiation 15 due to contaminant components using the light detection unit 10, and can simultaneously and continuously measure the dose of radiation 15 due to contaminant components and the dose of radiation 9 due to the detectable liquid 6 using the light detection unit 21. Furthermore, in the radiation monitor 1G, the photodetectors 10 and 21 are connected to a plurality of phosphor layers 3, so that the photodetectors 10 and 21 can be shared, thereby enabling cost reduction.

[0059] 2. Configuration of Radiation Monitor (Second Embodiment) [Radiation monitor configuration] Next, a second embodiment of the radiation monitor will be described. Fig. 14 shows a schematic configuration (perspective view) of a radiation monitor 20 according to the second embodiment. Fig. 15 shows a cross-sectional view of the radiation monitor 20 shown in Fig. 14 taken along line AA, and Fig. 16 shows a cross-sectional view of the radiation monitor 20 taken along line BB. As shown in Figures 14-16, the radiation monitor 20 of the second embodiment includes a contamination prevention layer 12 between the β-ray transparent layer 4 and the flow path section 5 in the radiation monitor 1 of the first embodiment shown in Figures 1-3 described above. Note that the radiation monitor 20 of the second embodiment can have the same configuration as the radiation monitor 1 of the first embodiment described above, except for the configuration related to the contamination prevention layer 12. Therefore, detailed description of the same configuration as the radiation monitor 1 of the first embodiment will be omitted below.

[0060] [Anti-pollution layer] The radiation monitor 20 shown in Figures 14-16 has a contamination prevention layer 12 on the wall surface of the flow path section 5. That is, the radiation monitor 20 has the contamination prevention layer 12 between the detectable liquid 6 and the β-ray transparent layer 4 in the flow path section 5. The contamination prevention layer 12 is formed in contact with the inner wall of the β-ray transparent layer 4. The inner wall side of the contamination prevention layer 12 forms the flow path section 5 through which the detectable liquid 6 flows.

[0061] Normally, when the detectable liquid 6 is supplied into the flow path section 5, radioactive nuclides contained in the detectable liquid 6 adhere to the inner wall of the flow path section 5. As a result, the inner wall of the flow path section 5 is contaminated with the radioactive nuclides in the detectable liquid 6 being supplied. Furthermore, the degree of contamination of the inner wall of the flow path section 5 by these nuclides increases with the supply amount and supply time of the detectable liquid 6. When the inner wall of the flow path section 5 is contaminated with radioactive nuclides, radiation originating from the nuclides (contamination) attached to the inner surface of the flow path section 5 is mixed into the radiation from the radioactive material in the detectable liquid 6, which is the object of measurement by the radiation monitor 20, resulting in so-called contamination.

[0062] The radiation monitor 20 has a contamination prevention layer 12 on the inner wall of this flow path section 5, thereby preventing adhesion (contamination) of radionuclides to the β-ray transparent layer 4. Furthermore, by providing the contamination prevention layer 12, even if contamination by radionuclides occurs, the contamination can be removed by removing and replacing the contamination prevention layer 12. Therefore, the radiation monitor 20 does not need to replace the phosphor layer 3 or the β-ray transparent layer 4 when contamination occurs, and the cost of replacing the phosphor layer 3 or the β-ray transparent layer 4 can be reduced.

[0063] The contamination prevention layer 12 is not particularly limited as long as it is permeable to the detection liquid 6. The contamination prevention layer 12 is composed of, for example, a chamber, hose, tube, etc. made of carbon fiber, PVC (polyvinyl chloride), or other resin. By configuring the contamination prevention layer 12 with a hose or tube, the contamination prevention layer 12 can be easily removed and replaced. The contamination prevention layer 12 may also be formed by a coating layer or a vapor deposition layer on the groove portion of the β-ray transparent layer 4 that constitutes the flow path portion 5. When the contamination prevention layer 12 is formed by a coating layer or a vapor deposition layer, the contamination prevention layer 12 can be removed and replaced by peeling it off and then forming a new layer.

[0064] The contamination prevention layer 12 may also be made of a water-repellent material. For example, a water-repellent silicone resin or fluororesin may be applied to the surface of the contamination prevention layer 12 to impart water repellency to the inner wall surface of the contamination prevention layer 12. The water-repellent nature of the inner wall of the contamination prevention layer 12 can prevent beta-ray-emitting nuclides from adhering to the contamination prevention layer 12. This reduces the frequency with which the contamination prevention layer 12 needs to be replaced.

[0065] The stain-preventing layer 12 has a density of 1.0 g / cm 3 More than 2.0g / cm 3 It is preferable to use a low density material such as: 3 If the density of the contamination prevention layer 12 is 2.0 g / cm or more, it is easy to prevent contamination of the β-ray transmission layer 4 and the phosphor layer 3 with nuclides. 3 If it is equal to or less than this, it is possible to reduce the attenuation of β rays in the contamination prevention layer 12. Therefore, it is possible to prevent the contamination prevention layer 12 from causing a decrease in the detection sensitivity of the radiation monitor 20. Furthermore, the thickness of the contamination prevention layer 12 is preferably 0.7 mm or more and 3 mm or less. If the thickness of the contamination prevention layer 12 is 0.7 mm or more, adhesion of nuclides to the β-ray transmitting layer 4 and the phosphor layer 3 can be suppressed, and manufacturing becomes easier. If the thickness of the contamination prevention layer 12 is 3 mm or less, attenuation of β-rays in the contamination prevention layer 12 can be reduced. Therefore, a decrease in the detection sensitivity of the radiation monitor 20 due to the contamination prevention layer 12 can be suppressed.

[0066] When the contamination prevention layer 12 is formed, for example, from a hose or a tube, the contamination prevention layer 12 can be placed on the inner wall of the beta ray permeable layer 4 by sandwiching the contamination prevention layer 12 between two beta ray permeable layers 4. When the contamination prevention layer 12 is formed from a coating layer, a vapor deposition layer, or the like, the contamination prevention layer 12 can be formed on the inner wall of the beta ray permeable layer 4 by forming a layer of the desired material in a semicircular groove formed on the surface of the beta ray permeable layer 4.

[0067] [Block diagram of radiation monitor] Next, a block diagram of a radiation monitor 20 according to the second embodiment described above is shown in FIG. 17. The radiation monitor 20 shown in FIG. 17 has a configuration in which the light detection unit 10 is omitted from the radiation monitor 20 shown in FIGS. 14-16. As shown in FIG. 17, the radiation monitor 20 generally includes a radiation detection unit 2 made up of a phosphor layer 3 and a β-ray transmission layer 4, a contamination prevention layer 12, and a flow path unit 5. A detectable liquid 6 flows through the flow path unit 5. The radiation monitor 20 shown in Fig. 17 has a configuration in which an anti-contamination layer 12 is added between the β-ray transmission layer 4 and the flow path portion 5 in the block diagram of the radiation monitor 1 of the first embodiment shown in Fig. 4 described above. Therefore, the radiation monitor 20 can prevent β-ray emitting nuclides from adhering to the anti-contamination layer 12. Furthermore, the radiation monitor 20 has the same configuration as the radiation monitor 1 of the first embodiment described above, except for the configuration related to the anti-contamination layer 12. Therefore, the radiation monitor 20 has the same characteristics and effects as the radiation monitor 1 of the first embodiment.

[0068] [Modified example of radiation monitor] Next, a modified example of the radiation monitor according to the second embodiment will be described. Note that in the following modified example, explanations of the same configurations as those of the first embodiment and its modified example, and the radiation monitor according to the second embodiment will be omitted. In addition, in the explanation of the modified example, only a block diagram of the radiation monitor will be shown. Furthermore, the same reference numerals will be used in the explanation of the same configurations as those in FIG. 4 above.

[0069] (Variation 1) FIG. 18 shows a block diagram of a radiation monitor according to Modification 1. The radiation monitor 20A shown in FIG. 18 has the same configuration as the radiation monitor 20 shown in FIGS. 14-16. The radiation monitor 20A shown in FIG. 18 has a configuration in which a contamination prevention layer 12 is added between the β-ray transmission layer 4 and the flow path section 5 in the block diagram of the radiation monitor 1A according to the first embodiment shown in FIG. 5 above. Therefore, the radiation monitor 20A has the same characteristics, actions, and effects as the radiation monitor 1A according to the first embodiment.

[0070] (Variation 2) Next, a block diagram of a radiation monitor according to a second modification is shown in Fig. 19. The radiation monitor 20B shown in Fig. 19 has a configuration in which a contamination prevention layer 12 is added between the β-ray transmission layer 4 and the flow path section 5 in the block diagram of the radiation monitor 1B according to the first embodiment shown in Fig. 6 above. Therefore, the radiation monitor 20B has the same characteristics, actions, and effects as the radiation monitor 1B according to the first embodiment.

[0071] (Variation 3) Next, a block diagram of a third modified example of the radiation monitor is shown in Fig. 20. The radiation monitor 20C shown in Fig. 20 has a configuration in which a contamination prevention layer 12 is added between the β-ray transmission layer 4 and the flow path section 5 in the block diagram of the radiation monitor 1C of the first embodiment shown in Fig. 7 above. Therefore, the radiation monitor 20C has the same characteristics, actions, and effects as the radiation monitor 1C of the first embodiment.

[0072] (Variation 4) Next, a block diagram of a fourth modified example of the radiation monitor is shown in Fig. 21. The radiation monitor 20D shown in Fig. 21 has a configuration in which a contamination prevention layer 12 is added between the β-ray transmission layer 4 and the flow path section 5 in the block diagram of the radiation monitor 1D of the first embodiment shown in Fig. 8 described above. Therefore, the radiation monitor 20D has the same characteristics, actions, and effects as the radiation monitor 1D of the first embodiment.

[0073] (Variation 5) Next, a block diagram of a fifth modified example of the radiation monitor is shown in Fig. 22. The radiation monitor 20E shown in Fig. 22 has a configuration in which a contamination prevention layer 12 is added between the β-ray transmission layer 4 and the flow path section 5 in the block diagram of the radiation monitor 1E of the first embodiment shown in Fig. 9 described above. Therefore, the radiation monitor 20E has the same characteristics, actions, and effects as the radiation monitor 1E of the first embodiment.

[0074] (Variation 6) Next, FIG. 23 shows a block diagram of a sixth modified example of the radiation monitor. The radiation monitor 20F shown in FIG. 23 has a configuration in which anti-contamination layers 12 are added between the flow path section 5 and the β-ray transmission layer 4 and between the flow path section 5 and the phosphor layer 3 in the block diagram of the radiation monitor 1F of the first embodiment shown in FIG. 10 described above. Specifically, the anti-contamination layer 12 is formed on the inner wall of the flow path section 5. Therefore, in a portion where the cylindrical (tubular) β-ray transmission layer 4 is formed to cover the outer periphery on one side of the flow path section 5, the anti-contamination layer 12 is formed between the flow path section 5 and the β-ray transmission layer 4. Furthermore, in a portion of the inner wall of the flow path section 5 where the β-ray transmission layer 4 is not formed, the anti-contamination layer 12 is formed between the flow path section 5 and the phosphor layer 3. Therefore, the radiation monitor 20F has the same characteristics, functions, and effects as the radiation monitor 1F of the first embodiment.

[0075] (Variation 7) Next, Fig. 24 shows a block diagram of a seventh modified example of the radiation monitor. The radiation monitor 20G shown in Fig. 24 has a configuration in which an anti-contamination layer 12 is added between the flow path section 5 and the β-ray transmission layer 4 or the phosphor layer 3 in the block diagram of the radiation monitor 1G of the first embodiment shown in Fig. 11 above. Specifically, the first detection unit 2a has a configuration in which an anti-contamination layer 12 is added between the β-ray transmission layer 4 and the flow path section 5. Furthermore, the second detection unit 2b has a configuration in which an anti-contamination layer 12 is added between the phosphor layer 3 and the flow path section 5. Therefore, the radiation monitor 20G has the same characteristics, actions, and effects as the radiation monitor 1G of the first embodiment.

[0076] (Variation 8) Next, Fig. 25 shows a block diagram of an eighth modified example of a radiation monitor. The radiation monitor 20H shown in Fig. 25 has a configuration in which an anti-contamination layer 12 is added between the flow path section 5 and the β-ray transmission layer 4 or the phosphor layer 3 in the block diagram of the radiation monitor 1H of the first embodiment shown in Fig. 12 described above. Specifically, the first detection unit 2a has a configuration in which an anti-contamination layer 12 is added between the β-ray transmission layer 4 and the flow path section 5. Furthermore, the second detection unit 2b has a configuration in which an anti-contamination layer 12 is added between the phosphor layer 3 and the flow path section 5. Therefore, the radiation monitor 20H has the same characteristics, actions, and effects as the radiation monitor 1H of the first embodiment.

[0077] (Variation 9) Next, Fig. 26 shows a block diagram of a 9th modified example of the radiation monitor. The radiation monitor 20I shown in Fig. 26 has a configuration in which an anti-contamination layer 12 is added between the flow path section 5 and the β-ray transmission layer 4 or the phosphor layer 3 in the block diagram of the radiation monitor 1I of the first embodiment shown in Fig. 13 described above. Specifically, the first detection unit 2a has a configuration in which an anti-contamination layer 12 is added between the β-ray transmission layer 4 and the flow path section 5. Furthermore, the second detection unit 2b has a configuration in which an anti-contamination layer 12 is added between the phosphor layer 3 and the flow path section 5. Therefore, the radiation monitor 20I has the same characteristics, actions, and effects as the radiation monitor 1I of the first embodiment.

[0078] 3. Configuration of Radiation Monitor (Third Embodiment) [Radiation monitor configuration] Next, a third embodiment of the radiation monitor will be described. FIG. 27 shows a block diagram of a radiation monitor 30 according to the third embodiment. As shown in FIG. 27, the radiation monitor 30 includes a light-transmitting material layer 13 between the phosphor layer 3 and the photodetector 10. The radiation monitor 30 of the third embodiment can be configured similarly to the radiation monitor 20 of the second embodiment, except for the configuration related to the light-transmitting material layer 13. Therefore, detailed description of the configuration similar to that of the radiation monitor 1 of the first embodiment will be omitted below. The radiation monitor 30 according to the third embodiment is similar to the radiation monitor 1 shown in FIGS. 1-4 and the radiation monitor 20 shown in FIGS. 14-17, except that the light-transmitting material layer 13 is provided between the phosphor layer 3 and the photodetector 10. Therefore, perspective views and cross-sectional views of the radiation monitor 30 will be omitted.

[0079] [Light transmitting material layer] As shown in FIG. 27, the radiation monitor 30 of the third embodiment has a configuration in which a light-transmitting material layer 13 is added between the phosphor layer 3 and the light detection unit 10 in the block diagram of the radiation monitor 20 of the second embodiment shown in FIG. 17 described above. The light-transmitting material layer 13 transmits the photons generated in the phosphor layer 3 to the photodetector 10. The photodetector 10 detects the photons propagated by the light-transmitting material layer 13. The light-transmitting material layer 13 is disposed so as to cover the entire surface of the phosphor layer 3 that is connected to the photodetector 10. By covering the entire surface of the phosphor layer 3, the light-transmitting material layer 13 can suppress loss of photons generated in the phosphor layer 3. The light-transmitting material layer 13 is not particularly limited as long as it can transmit photons from the phosphor layer 3 to the photodetector 10, and light-transmitting materials such as glass and resin, light guides, etc. can be used. In addition, the shape of the light-transmitting material layer 13 is not particularly limited as long as it can efficiently transmit photons from the phosphor layer 3 to the photodetector 10.

[0080] The radiation monitor 30 has the light-transmitting material layer 13, which allows for increased transmittance and light-collecting efficiency, thereby improving sensitivity and reducing costs. Furthermore, the radiation monitor 30 has the light-transmitting material layer 13, which allows for efficient detection of photons generated in the phosphor layer 3 without the need for multiple light detecting units 10. Therefore, the radiation monitor 30 can improve the detection sensitivity of photons generated in the phosphor layer 3 and reduce the installation costs of the light detecting units 10. Furthermore, the radiation monitor 30 has the same configuration as the radiation monitor 1 of the first embodiment and the radiation monitor 20 of the second embodiment, except for the configuration related to the light transmitting material layer 13. Therefore, the radiation monitor 30 has the same characteristics and effects as the radiation monitor 1 of the first embodiment and the radiation monitor 20 of the second embodiment.

[0081] [Modified example of radiation monitor] Next, a modified example of the radiation monitor according to the third embodiment will be described. The modified example of the radiation monitor according to the third embodiment can be configured by adding a light-transmitting material layer 13 between the phosphor layer 3 and the light detection unit 10 to the configuration of the modified example of the second embodiment shown in FIGS. 18-26 above. Specifically, the configuration of the radiation monitors 20A-20I according to the modified examples of the second embodiment shown in FIGS. 18-26 above can be configured by adding a light-transmitting material layer 13 between the phosphor layer 3 and the light detection unit 10, similar to the radiation monitor 30 shown in FIG. 27 above. For this reason, in the following description, as an example of a modified example of the radiation monitor according to the third embodiment, only a configuration in which a light-transmitting material layer 13 is added between the phosphor layer 3 and the light detection unit 10 to the configuration of the radiation monitor 20E according to the modified example 5 of the second embodiment shown in FIG. 22 above will be described. In addition, a modified example of the radiation monitor according to the third embodiment can also be configured by adding a light-transmitting material layer 13 between the phosphor layer 3 and the light detection unit 10 to the configuration of the modified example of the first embodiment shown in Figures 5-13 above.

[0082] (Variation) Figure 28 shows a block diagram of a modified example of the radiation monitor of the third embodiment. The radiation monitor 30A shown in Figure 28 generally includes a radiation detection unit 2 made up of a phosphor layer 3 and a β-ray transmission layer 4, a contamination prevention layer 12, and a flow path section 5. The radiation detection unit 2 is formed in a circular shape so as to cover the outer periphery of the flow path section 5, which has a cylindrical cross section. In other words, the β-ray transmission layer 4 is formed in a cylindrical (tubular) shape that encloses the flow path section 5. The phosphor layer 3 is also formed in a cylindrical (tubular) shape that encloses the β-ray transmission layer 4. Furthermore, in the radiation monitor 30A, a light-transmitting material layer 13 is formed to cover the entire periphery in the cross-sectional direction of the phosphor layer 3. The light-detecting unit 10 and the light-detecting unit 21 are connected to the light-transmitting material layer 13. The radiation monitor 30A has a light-transmitting material layer 13 that covers the entire periphery of the phosphor layer 3 in the cross-sectional direction, and is therefore able to efficiently guide photons from the β-ray transmitting layer 4 and phosphor layer 3 to the light detecting units 10 and 21. As a result, the sensitivity of the radiation monitor 30A is improved due to the increased transmittance and light-collecting efficiency provided by the light-transmitting material layer 13. Furthermore, the radiation monitor 30 has the same configuration as the radiation monitor 20 of the second embodiment described above, except for the configuration related to the light-transmitting material layer 13. Therefore, the radiation monitor 30 has the same characteristics and effects as the radiation monitor 20 of the second embodiment.

[0083] It should be noted that the present invention is not limited to the above-described embodiments and various modifications are possible. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to an embodiment including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete part of the configuration of each embodiment, or to add or replace other configurations. [Explanation of symbols]

[0084] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 20H, 20I, 30, 30A Radiation monitor, 10, 21, 22 Light detection unit, 11 Photon reflection layer, 12 Contamination prevention layer, 13 Light transmission material layer, 2 Radiation detection unit, 2a First detection unit, 2b Second detection unit, 3 Phosphor layer, 4 β-ray transmission layer, 5 Flow path unit, 51 Straight flow path unit, 52 Curved flow path unit, 53, 54 Opening, 6 Detected liquid, 7, 8 Radioactive nuclide, 9, 15 Radiation

Claims

1. a flow path portion through which a detection liquid containing a radionuclide flows; a phosphor layer that emits photons upon interaction with radiation emitted by the radionuclide; a β-ray transparent layer disposed between the phosphor layer and the flow path portion, which attenuates and absorbs radiation emitted by the radionuclide in the flow path portion. Radiation monitor.

2. The β-ray transmitting layer has a density of 1.0 g / cm ３ is The radiation monitor according to claim 1 .

3. a light detection unit connected to the phosphor layer that detects photons generated in the phosphor layer; The radiation monitor according to claim 1 .

4. A contamination prevention layer is provided on the wall surface of the flow path portion The radiation monitor according to claim 1 .

5. The fluorescent layer includes a plurality of flow path portions and a plurality of fluorescent layers corresponding to the plurality of flow path portions. The radiation monitor according to claim 1 .

6. A photon reflecting layer is provided between the phosphor layers. The radiation monitor according to claim 5 .

7. The plurality of phosphor layers each have a different emission wavelength. The radiation monitor according to claim 5 .

8. The phosphor layer contains a trivalent rare earth element. The radiation monitor according to claim 1 .

9. The β-ray transparent layer contains a phosphor that emits photons upon interaction with the radiation emitted by the radionuclide. The radiation monitor according to claim 1 .

10. The thickness of the beta ray transmitting layer is equal to or less than the range of the radiation to be detected. The radiation monitor according to claim 1 .

11. The β-ray transmitting layer contains the phosphor having an emission wavelength different from that of the phosphor layer. The radiation monitor according to claim 9.

12. a first photodetector connected to the phosphor layer; a second photodetector connected to the β ray transmission layer; The radiation monitor according to claim 9.

13. A photon reflecting layer is provided between the phosphor layer and the β-ray transmitting layer. The radiation monitor of claim 12.

14. a light-transmitting material connected between the phosphor layer and the light-detecting unit; The radiation monitor according to claim 3 .

Images