Radiation monitor

Abstract

To provide a radiation monitor capable of improving detection sensitivity.SOLUTION: Provided is a radiation monitor that comprises: a radiation detection unit including a solid phosphor that emits photons in response to incident radiation; a flow path through which a liquid to be detected flows, the flow path being provided inside the phosphor; and a light detection unit that detects the photons emitted from the phosphor and converts the photons into an electrical signal. The flow path has a portion whose periphery is covered with the phosphor in a cross section in a direction orthogonal to the flow direction of the liquid to be detected.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] In order to measure radiation from nuclides in liquids such as water, radiation measuring devices using, for example, liquid scintillators, ionization chambers, solid scintillators, etc. are used. In general, the maximum range of beta rays generated from Sr-90 and Y-90 in liquids is short, about 1.1 cm. For this reason, badge measurements are performed by sampling. For example, a radiation monitor has been proposed in which a sampling container through which the liquid to be detected passes is placed 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 measure the concentration of the radioactive material. Such a radiation monitor using a solid scintillator is expected to be a method capable of measuring radioactive nuclides in liquids such as water online. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-178336 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the radiation monitor described in Patent Document 1, photons are generated within the flat surface of the scintillator disposed opposite the sampling container, and therefore the amount of photons generated is small, resulting in low detection sensitivity.

[0005] In order to solve the above-mentioned problems, the present invention provides a radiation monitor capable of improving detection sensitivity.

[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 radiation detection unit including a solid phosphor that emits photons in response to incident radiation, a flow path through which a detectable liquid flows that is provided within the phosphor, and a light detection unit that detects the photons emitted from the phosphor and converts them into an electrical signal. The flow path has a portion that is surrounded by the phosphor in a cross section perpendicular to the flow direction of the detectable liquid.

[0008] The radiation monitor of the present invention includes a radiation detection unit having a solid phosphor that emits photons in response to incident radiation, a flow path provided within the phosphor through which a detectable liquid from the outside flows, and a light detection unit that detects the photons emitted from the phosphor and converts the photons into an electrical signal. The flow path communicates from the inlet to the outlet of the detectable liquid disposed in the phosphor by at least one of a straight flow path portion in which the flow portion of the detectable liquid is formed in a straight line and a curved flow path portion in which the flow portion is formed in a curved line. Effect of the Invention

[0009] According to the present invention, it is possible to provide a radiation monitor capable of improving detection sensitivity.

[0010] Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing a schematic configuration of a radiation monitor according to a first embodiment. [Diagram 2] 2 is a cross-sectional view taken along line AA of the radiation monitor shown in FIG. 1. [Diagram 3] 2 is a cross-sectional view of the radiation monitor shown in FIG. 1 taken along line BB. [Figure 4]1 is a cross-sectional view (corresponding to line AA) of a radiation monitor according to a second embodiment. [Diagram 5] 11 is a cross-sectional view (corresponding to line BB) of a radiation monitor according to a second embodiment. [Figure 6] 11 is a cross-sectional view (corresponding to line AA) of a radiation monitor according to a third embodiment. [Figure 7] 11 is a cross-sectional view (corresponding to line BB) of a radiation monitor according to a third embodiment. [Figure 8] 13A to 13C are diagrams illustrating a method for manufacturing an anti-contamination layer of a radiation monitor according to a third embodiment. [Figure 9] FIG. 11 is a cross-sectional view (corresponding to line AA) of a radiation monitor according to a fourth embodiment. [Figure 10] FIG. 11 is a cross-sectional view (corresponding to line BB) of a radiation monitor according to a fourth embodiment. [Figure 11] FIG. 11 is a cross-sectional view (corresponding to line AA) of a radiation monitor according to a fourth embodiment. [Figure 12] FIG. 11 is a cross-sectional view (corresponding to line BB) of a radiation monitor according to a fourth embodiment. [Figure 13] 13 is a cross-sectional view (corresponding to line AA) of a radiation monitor according to a fifth embodiment. [Figure 14] FIG. 13 is a cross-sectional view (corresponding to line AA) of a radiation monitor according to a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 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, the same reference numerals are used to designate common members. Furthermore, in the drawings used in this specification, the same reference numerals are used to designate the same or corresponding components, and repeated description of these components may be omitted.

[0013] The explanation will be given in the following order. 1. Configuration of the Radiation Monitor (First Embodiment) 2. Configuration of Radiation Monitor (Second Embodiment) 3. Configuration of Radiation Monitor (Third Embodiment) 4. Configuration of Radiation Monitor (Fourth Embodiment) 5. Configuration of Radiation Monitor (Fifth Embodiment) 6. Configuration of Radiation Monitor (Sixth Embodiment)

[0014] 1. Configuration of Radiation Monitor (First Embodiment) 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. 1, the radiation monitor 1 includes a radiation detection unit 2 and a light detection unit 6. The radiation detection unit 2 and the light detection unit 6 that configure the radiation monitor 1 will be described below.

[0015] [Radiation detection section] 1 and 2, the radiation detection unit 2 is composed of a phosphor 3 and a flow path 4. The flow path 4 is formed within the phosphor 3, and a detectable liquid 5 flows through the flow path 4. The phosphor 3 interacts with β-rays from the detectable liquid 5 in the flow path 4 to emit photons.

[0016] (Phosphor) The phosphor 3 is made of a solid composition to form a flow path 4 therein. The phosphor 3 is not particularly limited as long as it is a composition that exhibits luminescence, and examples of such luminescence 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 3 is, for example, made of NaI, CsI, LiI, SrI2, Bi4Ge3O 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 , Cs2LiYCl6, Cs2HfI6, ScTaO4, LaTaO4, LuTaO4, GdTaO4, YTaO4, InBO3, Y2O2S, ZnSiO4, sialon phosphor, and other light-transmitting materials, and light-transmitting materials containing rare earth elements such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, or elements, ions, and fluorescent materials such as Tl, Na, Ag, W, Cu, Al, Au, Mn, and CO3. More specifically, examples include InBO3:Tb, InBO3:Eu, ZnS:Cu, ZnS:Al, ZnS:Au, Y2O2S:Eu, Y2O2S:Tb, ZnSiO4:Mn, and the like.

[0017] The valence of the element ion contained in the phosphor 3 is not particularly limited as long as it can be used for luminescence, and for example, monovalent, divalent, trivalent, tetravalent, etc. can be used. Furthermore, as the phosphor 3, for example, an organic phosphor such as a complex, an organic compound, a plastic scintillator, etc. can also be used.

[0018] (Flow path) The radiation detection unit 2 includes two phosphors 3 bonded together. Each phosphor 3 has a symmetrical semicircular groove on one of its main surfaces. The phosphors 3 are bonded together with the semicircular grooves aligned, forming a tubular cavity inside the phosphor 3. This tubular cavity has openings 43, 44 at two locations, one at a given location on the surface of the phosphor 3 and the other at another location on the surface. The tubular cavity communicates with the openings 43, 44. The communicating cavity inside the phosphor 3 is a flow path 4 through which a detectable liquid 5 containing a radioactive nuclide flows. Therefore, the radiation detection unit 2 has a flow path 4 formed by a tubular cavity formed inside the phosphor 3.

[0019] A detectable liquid 5, indicated by an arrow in FIG. 2, is supplied from the outside to the flow path 4. In FIG. 2, the direction of the arrow indicates the flow direction of the detectable liquid 5. The detectable liquid 5 flows into the flow path 4 from one opening 43 (inlet). The detectable liquid 5 passes through the flow path 4 and is discharged from the other opening 44 (outlet). In the radiation monitor 1 shown in FIG. 1, the phosphor 3 is formed as a rectangular parallelepiped, as an example. The shape of the phosphor 3 is not particularly limited, and may be any shape as long as the flow path 4 can be formed therein and photons can be detected by the light detection unit 6.

[0020] Since the flow path 4 is a tubular hollow portion formed in the phosphor 3, the periphery is covered with the phosphor 3. That is, the flow path 4 has a portion whose entire periphery is covered with the phosphor 3 in a cross section perpendicular to the flow direction of the detection liquid 5. Note that, although the entire flow path 4 is covered with the phosphor 3 in the radiation monitor 1 shown in FIG. 1, this is not limited thereto. It is sufficient that at least a part of the periphery of the flow path 4 is covered with the phosphor 3. Therefore, the flow path 4 may have a portion that is not covered with the phosphor 3 or a portion whose periphery is not covered with the phosphor 3.

[0021] The flow path 4 has a straight flow path section 41 in which the flow portion is formed in a straight line, and a curved flow path section 42 in which the flow portion is formed in a curved line. The flow path 4 is communicated from the inlet to the outlet by a combination of the straight flow path section 41 and the curved flow path section 42. For this reason, in the configuration shown in FIG. 2, the detectable liquid 5 flows into the straight flow path section 41 from an opening 43 (inlet) at the bottom of the drawing. Then, the detectable liquid 5 flows from the straight flow path section 41 into the curved flow path section 42. Furthermore, the detectable liquid 5 flows from the curved flow path section 42 into the straight flow path section 41 at the top of the drawing and is discharged from an opening 44 (outlet). The flow path 4 may be formed only of the straight flow path portions 41, or may be formed only of the curved flow path portions 42. In addition, the flow path 4 may be such that the straight flow path portions 41 are directly connected to each other, or the curved flow path portions 42 are directly connected to each other.

[0022] The flow path 4 shown in Fig. 2 has a non-linear folded shape formed by a combination of a straight flow path section 41 and a curved flow path section 42. The shape of the flow path 4 is not limited to this. For example, the flow path 4 may have an inlet and an outlet formed on another surface of the phosphor 3, and may be linearly connected from the inlet to the outlet. The flow path 4 may also have a configuration in which a plurality of straight flow path sections 41 are arranged in parallel positions, a configuration in which they are arranged in twisted positions, or a configuration in which a plurality of curved flow path sections 42 form a plurality of folded sections. 1, the flow path 4 is arranged in a two-dimensional direction by the straight flow path portion 41 extending in the x-axis direction and the curved flow path portion 42 extending in the y-axis direction, but is not limited to this shape. For example, the flow path 4 may be formed by a cavity portion arranged in a three-dimensional direction in which at least one of the straight flow path portion 41 and the curved flow path portion 42 extends in the z-axis direction. In this way, the flow path 4 may be connected linearly or non-linearly from the inlet to the outlet by at least one of the straight flow path portion 41 and the curved flow path portion .

[0023] The cross-sectional shape of the flow path 4 is not particularly limited as long as it allows the detection liquid 5 to pass through it. For example, by making the inner diameter of the flow path 4 1.1 cm or less, the attenuation of β rays in water can be reduced, and the detection sensitivity of β rays can be improved. 1 and 3 has a cylindrical cross section, but the cross-sectional shape of the flow channel 4 is not limited thereto. The cross-sectional shape of the flow channel 4 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 channel 4 is a constant value. It is also preferable that the cross-sectional shape of the flow channel 4 does not change. By not changing the inner diameter or cross-sectional shape, the radiation monitor 1 can stabilize the detection sensitivity.

[0024] (Manufacturing method of radiation detection unit) The phosphor 3 can be manufactured by using, for example, a floating zone method, a Czochralski method (pulling-up method), a micro-pulling-down method, a Bridgman method, a Bernoulli method, organic synthesis, or the like. The flow path 4 can be manufactured by applying a method capable of micromachining the phosphor 3. For example, a semicircular groove is formed on the surface of the phosphor 3 by using mechanical processing, chemical reaction, or the like. Then, the processed surfaces of the phosphors 3 with the grooves formed thereon are bonded together. In this way, the radiation detection unit 2 having the flow path 4 formed inside the phosphor 3 can be manufactured. Furthermore, when it is difficult to process a non-linear shape due to the material of the solid phosphor, etc., the difficulty of processing may be relatively reduced by forming only the difficult-to-process portion from a material other than phosphor. In this way, the radiation detection unit may be realized by a combination of phosphor and a material other than phosphor. As an example of the folded shape, the folded shape can be described as a shape having a flow path longer than the sum of the vertical and horizontal dimensions of the processing surface. This allows the light detector to be placed near the light emission source, thereby improving detection efficiency.

[0025] [Light detection section] The light detection unit 6 is disposed adjacent to the phosphor 3 of the radiation detection unit 2. The radiation monitor 1 continuously measures the dose of radiation in the detection target liquid 5 in the flow path 4, for example. The light detection unit 6 detects photons generated by the phosphor 3. The light detection unit 6 converts the photons generated by the phosphor 3 into an electric pulse signal. The light detection unit 6 is not particularly limited as long as it can convert photons into an electric pulse signal, and for example, a photomultiplier tube, an avalanche photodiode, or the like can be used.

[0026] [Liquid to be detected] The liquid to be detected 5 contains a nuclide that generates radiation. The nuclide is not particularly limited, but is, for example, Sr-90 or Y-90. The generated radiation is not particularly limited, but includes particle rays such as α-rays, β-rays, and neutron rays, and electromagnetic waves such as X-rays and γ-rays. Among them, the generated radiation is preferably α-rays and β-rays. The liquid to be detected 5 contains the nuclide in a dissolved or dispersed state. The portion of the liquid to be detected 5 excluding the nuclide is not particularly limited as long as it is liquid, and is, for example, aqueous solutions such as nuclear power plant treated water, seawater, and brackish water (brine water, etc.), but may be fresh water.

[0027] [Water flow direction / layout direction] In the radiation monitor 1, when the y-axis direction is the vertical direction, the detectable liquid 5 is supplied from an opening 43 at the bottom (below the y-axis) of the flow path 4 to an opening 44 at the top (above the y-axis) as shown by the arrow in Fig. 2. By supplying the detectable liquid 5 in this direction, the flow path 4 can be filled with the detectable liquid 5 without leaving any cavities inside. As a result, the adjacent area between the phosphor 3 and the detectable liquid 5 can be increased. The flow direction of the detection liquid 5 is not particularly limited, and for example, when the y-axis direction is the vertical direction, the detection liquid 5 may be supplied from the opening 44 at the upper part (above the y-axis) of the flow path 4 to the opening 43 at the lower part (below the y-axis). This supply direction does not require a pressure device such as a pump to supply the detection liquid 5, so that mechanical vibration noise caused by the pressure device can be eliminated and measurement accuracy is improved.

[0028] 2, the radiation detection unit 2 is arranged so that the straight flow path portion 41 is aligned in the y-axis direction. In the radiation monitor 1, the arrangement direction of the radiation detection unit 2 is not particularly limited, and for example, the radiation detection unit 2 may be arranged so that the x-axis direction or the z-axis direction is the vertical direction. Furthermore, the radiation detection unit 2 may be arranged at an angle with any direction between the x-, y-, and z-axis directions as the vertical direction. When the radiation detection unit 2 is arranged in this manner, the detectable liquid 5 is supplied from one of the openings 43, 44 arranged in the horizontal direction, and the detectable liquid 5 is discharged from the other.

[0029] In the radiation monitor 1 having the above-mentioned configuration, the periphery of the flow path 4 is covered with the phosphor 3. Therefore, in the radiation monitor 1, the surface area of ​​the phosphor 3 in contact with the detectable liquid 5 can be made larger than in a configuration using a conventional flat-plate solid scintillator. That is, in a configuration using a conventional flat-plate solid scintillator, the flow path 4 has at least a part that is not adjacent to the phosphor 3 in a cross section perpendicular to the flow direction of the detectable liquid 5. Therefore, radiation emitted in the direction of the part that is not adjacent to the phosphor 3 does not enter the solid scintillator (phosphor), resulting in detection loss. In contrast, in the radiation monitor 1 of the present embodiment described above, the phosphor 3 covers the entire periphery in the cross-sectional direction of the flow path 4, so that the probability that radiation emitted from the detectable liquid 5 enters the phosphor 3 is improved. In particular, the bending of the flow path 4 makes it easier for radiation emitted in the direction along the flow direction to enter the phosphor 3. Furthermore, the radiation monitor 1 has a folded shape formed by combining a straight flow path section 41 and a curved flow path section 42. The folded shape of the radiation monitor 1 enables the length of the flow path 4 to be increased. As a result, the adjacent area of ​​the detectable liquid 5 and the phosphor 3 in the flow path 4 of the radiation monitor 1 increases, increasing the probability of reaction between the phosphor 3 and radiation. Therefore, by having the flow path 4 formed in the phosphor 3, the radiation monitor 1 increases the probability of reaction between the phosphor 3 and radiation, improving the detection sensitivity.

[0030] 2. Configuration of Radiation Monitor (Second Embodiment) Next, a second embodiment of the radiation monitor will be described. The radiation monitor of the second embodiment differs from the radiation monitor of the first embodiment described above only in the configuration of the flow path. Therefore, detailed description of the same configuration as the radiation monitor of the first embodiment described above will be omitted. Figures 4 and 5 show a schematic configuration of a radiation monitor 1A according to the second embodiment. The radiation monitor 1A shown in Figure 4 corresponds to a cross-sectional view taken along line AA of the radiation monitor 1 shown in Figure 1. The radiation monitor 1A shown in Figure 5 corresponds to a cross-sectional view taken along line BB of the radiation monitor 1 shown in Figure 1. The radiation monitor 1A shown in Figures 4 and 5 differs from the radiation monitor 1 shown in Figure 1 only in the flow path 4, but the outer shape of the phosphor 3 and the configuration of the light detection unit 6 are the same.

[0031] 4 and 5 has a flow path 4 in a phosphor 3 constituting a radiation detection unit 2. As shown in Fig. 4, the flow path 4 has openings 43 and 44 on opposing sides on which the light detection unit 6 is not disposed. The detectable liquid 5 flows into the flow path 4 from one opening 43 (inlet), passes through the flow path 4, and is discharged from the other opening 44 (outlet).

[0032] The flow path 4 has three straight flow path sections 41 in which the flow portion is formed in a straight line, and two curved flow path sections 42 in which the flow portion is formed in a curved line. The straight flow path sections 41 of the flow path 4 are connected by the curved flow path sections 42. The flow path 4 is extended in two-dimensional directions by connecting the straight flow path sections 41 extending in the x-axis direction by the curved flow path sections 42 extending in the y-axis direction. That is, the two curved flow path sections 42 form two turning back sections in the flow path 4.

[0033] As described above, in the radiation monitor 1A, the flow path 4 that communicates from the opening 43 (inlet) to the opening 44 (outlet) is formed in the phosphor 3 by the communicating straight flow path portion 41 and the communicating curved flow path portion 42. That is, the flow path 4 of the radiation monitor 1A is entirely covered by the phosphor 3 in a cross section perpendicular to the flow direction of the detection liquid 5, similar to the first embodiment described above.

[0034] As in the radiation monitors 1, 1A of the first and second embodiments described above, the flow path 4 can be of any shape as long as it is formed inside the phosphor 3. In the radiation monitors 1, 1A, the length of the flow path 4 covered by the phosphor 3 is increased, thereby making it possible to increase the surface area of ​​the phosphor 3 that comes into contact with the detectable liquid 5. As a result, the radiation monitors 1, 1A can increase the probability of reaction between the phosphor 3 and radiation. In addition, the radiation monitor 1, 1A has a folded shape that connects the straight flow path section 41 and the curved flow path section 42, but the number of straight flow path sections 41 and the curved flow path sections 42 is not limited, and the number of folds can be increased to form a longer flow path 4. In this embodiment, only one flow path 4 that communicates with the inside of the phosphor 3 is shown, but other flow paths that do not communicate with the flow path 4 may be formed in the phosphor 3.

[0035] 3. Configuration of Radiation Monitor (Third Embodiment) Next, a third embodiment of the radiation monitor will be described. The radiation monitor of the third embodiment differs from the radiation monitor of the second embodiment only in that it has a contamination prevention layer in the flow path. Therefore, detailed description of the same configuration as the radiation monitors of the first and second embodiments will be omitted.

[0036] 6 and 7 show a schematic configuration of a radiation monitor 1B according to a third embodiment. The radiation monitor 1B shown in FIG. 6 corresponds to a cross-sectional view taken along line AA of the radiation monitor 1 shown in FIG. 1. The radiation monitor 1B shown in FIG. 7 corresponds to a cross-sectional view taken along line BB of the radiation monitor 1 shown in FIG. The radiation monitor 1B shown in FIGS. 6 and 7 has a flow path 4 having a similar shape to the radiation monitor 1A shown in FIGS. 4 and 5.

[0037] 6 and 7 has a flow path 4 in a phosphor 3 constituting a radiation detection unit 2. Furthermore, the radiation monitor 1B has a contamination prevention layer 7 on the wall surface of the flow path 4. That is, in the radiation monitor 1B, the contamination prevention layer 7 is interposed between the detectable liquid 5 and the phosphor 3 in the flow path 4.

[0038] The contamination prevention layer 7 is in contact with the inner surface of the flow channel 4, and can prevent contamination of the phosphor 3 caused by the detection liquid 5 flowing inside the contamination prevention layer 7. Usually, when the detectable liquid 5 is supplied into the flow path 4, radioactive nuclides contained in the detectable liquid 5 adhere to the inner wall of the flow path 4. As a result, the inner wall of the flow path 4 is contaminated by the radioactive nuclides of the detectable liquid 5 being supplied. Furthermore, the degree of contamination of the inner wall of the flow path 4 by this nuclide increases according to the supply amount and supply time of the detectable liquid 5. When the surface is contaminated by the nuclide, radiation originating from the nuclide (contamination) adhered to the inner surface of the flow path 4 is mixed into the radiation from the radioactive material in the detectable liquid 5, which is the object of measurement by the radiation monitor 1B, and so-called contamination occurs.

[0039] The radiation monitor 1B has a contamination prevention layer 7 on the inner wall of the flow path 4, thereby making it possible to prevent various adhesions (contamination) of the phosphor 3. Furthermore, by providing the contamination prevention layer 7, even if contamination occurs, the contamination can be removed by removing and replacing the contamination prevention layer 7. Therefore, with the radiation monitor 1B, it is not necessary to replace the phosphor 3 when contamination occurs, making it possible to reduce the cost of replacing the phosphor 3.

[0040] The contamination prevention layer 7 is not particularly limited as long as it is permeable to the detection liquid 5. The contamination prevention layer 7 is composed of, for example, a hose or tube made of PVC (polyvinyl chloride) or other resin. By configuring the contamination prevention layer 7 with a hose or tube, the contamination prevention layer 7 can be easily removed and replaced. Furthermore, the contamination prevention layer 7 may be formed by a coating layer, a deposition layer, or the like, on the grooves of the phosphor 3 that constitutes the flow path 4. When the contamination prevention layer 7 is formed by a coating layer, a deposition layer, or the like, the contamination prevention layer 7 can be removed and replaced by peeling off the contamination prevention layer 7 and forming a new layer.

[0041] Furthermore, the contamination prevention layer 7 may be formed from a water-repellent material. For example, a water-repellent silicone resin or fluororesin may be applied to the surface of the contamination prevention layer 7 to impart water repellency to the inner wall surface of the contamination prevention layer 7. The water-repellent nature of the inner wall of the contamination prevention layer 7 can suppress adhesion of β-ray-emitting nuclides to the contamination prevention layer 7. This can reduce the frequency of replacement of the contamination prevention layer 7.

[0042] The stain-preventing layer 7 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 7 is 2.0 g / cm or more, it is easy to prevent contamination of the phosphor 3. 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 7. Therefore, it is possible to suppress a decrease in the detection sensitivity of the radiation monitor 1B due to the contamination prevention layer 7. Furthermore, the contamination prevention layer 7 preferably has a thickness of 0.7 mm or more and 3 mm or less. If the contamination prevention layer 7 has a thickness of 0.7 mm or more, adhesion of nuclides to the phosphor 3 can be suppressed, and manufacturing can be facilitated. If the contamination prevention layer 7 has a thickness of 3 mm or less, attenuation of β rays in the contamination prevention layer 7 can be reduced. This makes it possible to suppress a decrease in the detection sensitivity of the radiation monitor 1B caused by the contamination prevention layer 7.

[0043] An example of a method for manufacturing the contamination prevention layer 7 is shown in Fig. 8. When the contamination prevention layer 7 is formed of a hose or tube, the contamination prevention layer 7 can be placed in the flow path 4 by sandwiching the contamination prevention layer 7 between two phosphors 3, as shown in Fig. 8. Furthermore, when the contamination prevention layer 7 is formed as a coating layer or a vapor deposition layer, the contamination prevention layer 7 can be provided within the flow path 4 by forming a layer of a desired material in the semicircular groove formed on the surface of the phosphor 3 .

[0044] 4. Configuration of Radiation Monitor (Fourth Embodiment) Next, a fourth embodiment of the radiation monitor will be described. The radiation monitor of the fourth embodiment differs from the radiation monitor of the third embodiment only in the arrangement of the light detection unit. Therefore, detailed description of the same configuration as the radiation monitors of the first, second and third embodiments will be omitted.

[0045] 9 and 10 show a schematic configuration of a radiation monitor 1C according to the fourth embodiment. Also, FIGS. 11 and 12 show a schematic configuration of a radiation monitor 1D according to the fourth embodiment. The radiation monitors 1C and 1D shown in FIGS. 9 and 11 correspond to a cross-sectional view taken along line AA of the radiation monitor 1 shown in FIG. 1. The radiation monitors 1C and 1D shown in FIGS. 10 and 12 correspond to a cross-sectional view taken along line BB of the radiation monitor 1 shown in FIG. The radiation monitors 1C and 1D shown in FIGS. 9 to 12 have a flow path 4 and a contamination prevention layer 7 having the same shape as the radiation monitor 1A shown in FIGS. 6 and 7.

[0046] 9 to 12, in the radiation monitors 1C and 1D, the light detecting units 6 can be disposed at any position relative to the phosphor 3. By increasing the number of light detecting units 6, the photons generated in the phosphor 3 can be detected efficiently. In particular, by disposing the light detecting units 6 in accordance with the shape of the flow channel 4, the photons generated in the phosphor 3 can be detected efficiently. 9 and 10, the light detection units 6 are arranged at a total of six locations, three on each side of the phosphor 3 (x-axis direction in the drawing), in accordance with the position of the straight flow path section 41. Meanwhile, in the radiation monitor 1D shown in Figures 11 and 12, the light detection units 6 are arranged at a total of eight locations, three on each side of the phosphor 3 and one each on the top and bottom surfaces of the phosphor 3 (y-axis direction in the drawing), in accordance with the position of the straight flow path section 41. In this way, by increasing the number of connections of the light detecting sections 6 in the radiation monitors 1C and 1D, photons generated by the phosphor 3 can be detected efficiently, and the detection sensitivity can be improved. In the radiation monitors 1C and 1D, the photodetector 6 is connected to the surfaces other than the surface on which the openings 43 and 44 are formed, but the photodetector 6 may be connected to the surface on which the openings 43 and 44 are formed. Furthermore, the photodetector 6 is arranged in parallel in the y-axis direction in the drawing, but it may be arranged in parallel in the x-axis direction or in parallel in both the x-axis and y-axis directions.

[0047] 5. Configuration of Radiation Monitor (Fifth Embodiment) Next, a fifth embodiment of the radiation monitor will be described. The radiation monitor of the fifth embodiment differs from the radiation monitor of the third embodiment described above only in that the radiation monitor of the fifth embodiment has a light guide between the phosphor and the light detection unit. Therefore, detailed descriptions of the same configurations as those of the radiation monitors of the first, second and third embodiments described above will be omitted.

[0048] Fig. 13 shows a schematic configuration of a radiation monitor 1E according to a fifth embodiment. The radiation monitor 1E shown in Fig. 13 corresponds to a cross-sectional view taken along line BB of the radiation monitor 1 shown in Fig. 1. Note that a drawing of the radiation monitor 1E corresponding to the cross-sectional view taken along line AA of the radiation monitor 1 shown in Fig. 1 is the same as Fig. 6, and therefore will not be repeated.

[0049] As shown in Fig. 13, in the radiation monitor 1E, a light guide 8 is connected between the light detection unit 6 and the phosphor 3. The light guide 8 transmits photons generated in the phosphor 3 to the light detection unit 6. The light detection unit 6 detects the photons propagated by the light guide 8. The light guide 8 is installed so as to cover the entire surfaces of the phosphor 3 that face each other in the x-axis direction in the drawing. By covering the entire surfaces of the phosphor 3, it is possible to suppress the loss of photons generated in the phosphor 3.

[0050] The light guide 8 is not particularly limited as long as it can transmit photons of the phosphor 3 to the light detection unit 6, and can be made of glass, resin, or the like. Furthermore, the shape of the light guide 8 is not particularly limited as long as it can efficiently transmit photons from the phosphor 3 to the light detection unit 6 .

[0051] The radiation monitor 1E has the light guide 8 and can efficiently detect photons generated in the phosphor 3, without providing multiple light detection units 6. Therefore, the radiation monitor 1E can improve the detection sensitivity of photons generated in the phosphor 3 and reduce the installation cost of the light detection units 6.

[0052] 6. Configuration of Radiation Monitor (Sixth Embodiment) Next, a sixth embodiment of the radiation monitor will be described. The fifth embodiment of the radiation monitor is different from the second embodiment of the radiation monitor only in the shape of the flow path. Therefore, detailed description of the same configuration as the first and second embodiments of the radiation monitor will be omitted.

[0053] Fig. 14 shows a schematic configuration of a radiation monitor 1F according to a sixth embodiment. The radiation monitor 1F shown in Fig. 14 corresponds to a cross-sectional view taken along line AA of the radiation monitor 1 shown in Fig. 1. Note that in the radiation monitor 1F, a drawing corresponding to the cross-sectional view taken along line BB of the radiation monitor 1 shown in Fig. 1 is omitted since it is the same as Fig. 5. Also, the light detection unit is omitted in Fig. 14.

[0054] As shown in FIG. 14, in a radiation monitor 1F, a flow path 4 formed in a phosphor 3 is formed in a non-linear shape by only linear flow path portions 41. The flow path 4 has three straight flow path sections 41 extending in the x-axis direction in the drawing and three straight flow path sections 41 extending in the y-axis direction. In the radiation monitor 1F, the flow path 4 is formed in the phosphor 3, which communicates from the opening 43 (inlet) to the opening 44 (outlet) by the straight flow path sections 41 extending in the x-axis direction and the y-axis direction. In the flow path 4, the straight flow path sections 41 extending in the x-axis direction and the straight flow path sections 41 extending in the y-axis direction are connected by intersecting with each other. Therefore, the flow path 4 is arranged in a lattice shape in the phosphor 3, with the straight flow path sections 41 intersecting with each other.

[0055] The detectable liquid 5 flows from an opening 43 (inlet) at the bottom of the drawing into a straight flow path section 41 extending in the x-axis direction. The detectable liquid 5 then branches from the straight flow path section 41 extending in the x-axis direction into three connected straight flow path sections 41 extending in the y-axis direction and flows into each of them. Furthermore, the detectable liquid 5 that flows into each straight flow path section 41 extending in the y-axis direction branches and merges into each of the straight flow path sections 41 extending in the intersecting x-axis direction and flows down in the y-axis direction as it is. Furthermore, the detectable liquid 5 flows from the curved flow path section 42 into the straight flow path section 41 at the top of the drawing and is discharged from an opening 44 (discharge port).

[0056] As in the radiation monitor 1F, the flow path 4 formed in the phosphor 3 may be formed only by the straight flow path portion 41. Moreover, the flow path 4 does not have to be formed by a single flow path 4 from the opening 43 (inlet) to the opening 44 (outlet). As described above, the flow path 4 can be formed by a combination of only straight flow path portions 41, a combination of only curved flow path portions 42, a combination of straight flow path portions 41 and curved flow path portions 42, and the like. The flow path 4 can be made longer in length by having a turnback shape, a branching shape, or a merging shape. In the radiation monitor 1, by making the flow path length longer, the adjacent area between the detectable liquid 5 and the phosphor 3 in the flow path 4 is increased, and the probability of the phosphor 3 reacting with radiation is increased.

[0057] 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 having all of the configurations described. It is also possible to replace a 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 a part of the configuration of each embodiment, or to add or replace another configuration. [Explanation of symbols]

[0058] 1, 1A, 1B, 1C, 1D, 1E, 1F radiation monitor, 2 radiation detection section, 3 phosphor, 4 flow path, 5 liquid to be detected, 6 light detection section, 7 contamination prevention layer, 8 light guide, 41 straight flow path section, 42 curved flow path section, 43, 44 opening

Claims

1. a radiation detection unit including a solid phosphor that emits photons in response to incident radiation; a flow path provided within the fluorescent body through which a detection target liquid flows; a light detection unit that detects the photons emitted from the phosphor and converts them into an electrical signal; The flow path has a portion that is surrounded by the phosphor in a cross section perpendicular to a flow direction of the detection liquid. Radiation monitor.

2. The radiation detection unit includes a contamination prevention layer between the flow path and the solid phosphor.

2. The radiation monitor of claim 1.

3. The contamination prevention layer is removable from the solid phosphor.

3. The radiation monitor of claim 2.

4. The stain-preventing layer has water repellency.

3. The radiation monitor of claim 2.

5. The stain-preventing layer has a density of 2.0 g / cm ３ is less than or equal to 3. The radiation monitor of claim 2.

6. The flow path is The flow portion of the test liquid includes a plurality of linear flow passage portions formed linearly, The inlet and the outlet of the liquid to be detected are connected by the straight flow path portion.

2. The radiation monitor of claim 1.

7. The flow path is a curved flow path portion in which the detection liquid flows, The straight flow path portions are connected to each other via the curved flow path portions.

7. The radiation monitor according to claim 6.

8. The flow path is The straight flow passage portions are directly connected to each other.

7. The radiation monitor according to claim 6.

9. The flow channel has an inner diameter of 1.1 cm or less.

2. The radiation monitor of claim 1.

10. A light guide is provided between the light detection unit and the phosphor.

2. The radiation monitor of claim 1.

11. a radiation detection unit including a solid phosphor that emits photons in response to incident radiation; a flow path provided in the fluorescent body through which a detection target liquid flows from the outside; a light detection unit that detects the photons emitted from the phosphor and converts them into an electrical signal; The flow path is connected from the inlet to the outlet of the detection liquid disposed in the phosphor by at least one of a straight flow path portion in which the flow portion of the detection liquid is formed in a straight line and a curved flow path portion in which the flow portion is formed in a curved line. Radiation monitor.

12. The flow path is connected in a non-linear manner with the straight flow path portion and the curved flow path portion. The radiation monitor of claim 11.

13. The radiation detection unit includes a contamination prevention layer between the flow path and the solid phosphor.

13. The radiation monitor of claim 12.

14. The contamination prevention layer is removable from the solid phosphor. The radiation monitor of claim 13.

15. The flow path is realized by bonding together a groove formed on a processed surface of the radiation detection unit, The contamination prevention layer is removable from the solid phosphor when the bonding is released.

15. The radiation monitor of claim 14.

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