JP6630207B2 - Apparatus and method for measuring thermal neutron permeation amount of powder or granulated substance, and apparatus and method for quantitative analysis of element in powder or granulated substance - Google Patents

Description

  The present invention relates to an apparatus and a method for measuring the amount of thermal neutron permeation through a powder or a granulated product, and to an apparatus and a method for quantitatively analyzing elements in a powder or a granulated product.

  Boron in coal ash is controlled by the elution standard value in the Soil Contamination Countermeasures Law. For quantitative analysis of the amount of boron eluted from coal ash, it is necessary to prepare an eluate specified in the Environment Agency Notification No. 46 (Non-Patent Document 1).

Ministry of the Environment: "Environmental Standards for Soil Pollution", Notification of the Environment Agency, No. 46, (1991)

  However, preparation of an eluate according to the notification of the Environment Agency No. 46 requires immersion of coal ash in water and shaking treatment for as long as 6 hours, which results in the removal of boron from coal ash. There is a problem that it takes a long time to quantitatively analyze the elution amount. There is also a problem that performing such preprocessing itself is complicated.

  Incidentally, it has been reported that there is a correlation between the amount of boron eluted from coal ash and the boron concentration of coal ash (J. Jankowski, CR Ward, D. French, S. Groves: “Mobility of trace elements from selected Australian fly ashes and its potential impact on aquatic ecosystems ”, Fuel, 85, 243-256, (2006)., B. Cetin and AH Aydilek:“ pH and fly ash type effect on trace metal leaching from embankment soils ", Resources, Conservation and Recycling, 80, 107-117, (2013).).

  Therefore, if the boron concentration of coal ash can be quantitatively analyzed easily and quickly, the amount of boron eluted from coal ash can be easily and quickly predicted without preparing an eluate according to the Environment Agency Notification No. 46. It is considered possible.

  However, at present, a method for simply and quickly quantitatively analyzing the boron concentration of coal ash has not been established. For example, as a method for quantitatively analyzing the concentration of a trace element in a solid, a sediment survey method (Ministry of the Environment, Environmental Management Bureau, Water Environment Department: “About the Sediment Survey Method”, Kansui Osui No. 120725002, (2012). ) Is known, and it is possible to perform a quantitative analysis of the boron concentration of coal ash by this method. However, when this method is employed, it is necessary to perform a pretreatment of completely decomposing the coal ash by alkali melting or the like to form a solution, and it requires more labor and time than preparation of an eluate according to the Environment Agency Notification No. 46. Become. In addition, energy dispersive X-ray spectroscopy (EDS) is known as a method for quantitative analysis of trace elements that does not require a total decomposition treatment of solids. However, quantitative analysis of light element boron is difficult with this analysis method. It is.

  In addition, it is considered industrially extremely meaningful to establish a method for simply and quickly quantitatively analyzing the concentration of the constituent elements of not only coal ash but also powders or granules in general.

  Therefore, an object of the present invention is to provide an apparatus and a method for easily and quickly quantitatively analyzing the concentration of an element such as boron in a powder or a granulated substance such as coal ash.

  Further, the present invention provides a measuring device and a method capable of easily and quickly obtaining data required for quantitatively analyzing the concentration of an element such as boron for powder or granulated material such as coal ash. The purpose is to do.

  In order to solve such an object, the present inventor has proposed a method for simply and rapidly quantitatively analyzing the boron concentration of coal ash by a method completely different from the conventionally known method for quantitatively analyzing the concentration of trace elements in a solid. We studied diligently. As a result, a method of simply and quickly quantitatively analyzing the boron concentration of coal ash, and a configuration of a measuring device capable of easily and quickly acquiring data required for quantitatively analyzing the boron concentration of coal ash, have been developed. It has been established. And it is found that the method and the measuring device can be applied not only to coal ash but also to powders or granules in general, in which not only boron but also gadolinium and lithium can be quantitatively analyzed. Reached.

  Further, the present inventor has found that the configuration of the measurement apparatus is effective in suppressing measurement errors caused by uneven distribution and particle size variation of the element to be analyzed in the object to be analyzed, and is also effective in improving the measurement sensitivity. Have been found, and the present inventors have further studied variously, and have completed the present invention.

That is, the thermal neutron permeation measuring device of the present invention is a device for measuring the thermal neutron permeation amount of a substance to be analyzed using a powder or a granulated substance as an analysis object, and an outer cylinder and a concentric circle in the outer cylinder. A sample holder in which an analyte is accommodated, a neutron source that emits fast neutrons, and a fast neutron source that includes a bottom plate that closes one end of the outer tube and one end of the inner tube. A moderator for converting neutrons to thermal neutrons, a detector for detecting thermal neutrons, and at least a rotating mechanism, one of the neutron source and the detector is arranged to face the inner peripheral surface of the inner cylinder. , The other of which is arranged opposite to the outer peripheral surface of the outer cylinder, the neutron source is surrounded by the moderator, and the neutron source or detector arranged opposite to the outer peripheral surface of the outer cylinder is rotated by the rotating mechanism to sample for the Hol da in the circumferential direction of the sample holder are intended to measure relative rotation is performed

The thermal neutron transmission amount measurement method of the present invention includes an outer cylinder, an inner cylinder concentrically arranged in the outer cylinder, and a bottom plate that closes between one end of the outer cylinder and one end of the inner cylinder. A step of allowing thermal neutrons to be incident on one of an outer peripheral surface of an outer cylinder and an inner peripheral surface of an inner cylinder of a sample holder in which an object is accommodated, and detecting thermal neutrons transmitted through an analyte and emitted from the other. This step involves changing the incident position of thermal neutrons or the detection position of thermal neutrons relative to the sample holder in the circumferential direction of the sample holder so as to rotate and scan the analyte in the circumferential direction of the sample holder. While doing it.

  Next, the quantitative analysis device of the present invention is a device that quantitatively analyzes the concentration of the analysis target element in the analysis target, using the powder or granulated material as the analysis target, and boron, gadolinium or lithium as the analysis target element. The thermal neutron transmission measuring apparatus of the present invention, and the thermal neutron transmission measured by the thermal neutron transmission measuring apparatus of the present invention with the concentration of the element to be analyzed as a dependent variable for a plurality of samples of the same kind as the analyte. Means for calculating the concentration of the element to be analyzed in the analyte based on the simple regression function previously determined by performing the simple regression analysis and the amount of thermal neutron permeation of the analyte as the independent variable, At least.

  Further, the quantitative analysis method of the present invention is a method for quantitatively analyzing the concentration of an element to be analyzed in an object to be analyzed using powder or granulated material as an object to be analyzed and boron, gadolinium or lithium as an element to be analyzed. The step of measuring the thermal neutron transmission of the analyte by the thermal neutron transmission measurement method of the present invention, and for a plurality of samples of the same type as the analyte, the concentration of the element to be analyzed as a dependent variable, Using the thermal neutron transmission measured by the thermal neutron transmission measurement method as an independent variable, the analysis target is determined based on the simple regression function previously obtained by performing simple regression analysis and the thermal neutron transmission of the analyte. Calculating the concentration of the element to be analyzed in the substance.

  According to the thermal neutron transmission amount measuring apparatus and method of the present invention, such as the preparation of a wet decomposition solution by alkali melting determined by the sediment survey method or the like for the powder or granulated material to be analyzed The amount of thermal neutron permeation of the analyte can be easily and quickly measured without performing complicated and time-consuming preparation or the like.

  Further, according to the thermal neutron transmission amount measuring apparatus and method of the present invention, it is possible to perform nondestructive measurement of an analyte. Therefore, it is possible to collect and effectively utilize the analysis object subjected to the measurement. Further, unlike the preparation of a wet decomposition solution by alkali melting determined by the method for examining sediment or the like, no waste liquid or the like is generated after the wet decomposition, so that there is no need to perform these post-treatments.

  Further, according to the thermal neutron transmission amount measuring apparatus and method of the present invention, it is possible to easily suppress the measurement error caused by the uneven distribution of the element to be analyzed and the variation in particle diameter of the object to be analyzed, and to easily improve the measurement sensitivity.

  According to the quantitative analysis device and the quantitative analysis method of the element in the powder or the granulated material of the present invention, the analysis object by utilizing the thermal neutron transmission amount measured by the thermal neutron transmission measurement device and method of the present invention. Since the concentration of the element to be analyzed in a certain powder or granulated material is quantitatively analyzed, it is difficult and time-consuming to prepare a wet-decomposition solution by alkali melting as defined in the Sediment Survey Method. The element concentration in the analyte can be quantitatively analyzed from the measurement result obtained by subjecting the analyte to the measurement of the thermal neutron permeation amount without performing necessary preparations and the like. Therefore, it is possible to easily and quickly perform quantitative analysis of the concentration of the element to be analyzed in the object to be analyzed.

  Further, according to the quantitative analysis device and the quantitative analysis method of the element in the powder or the granulated material of the present invention, the analysis object using the thermal neutron transmission amount measured by the thermal neutron transmission measurement device and the method of the present invention. Since the concentration of the element to be analyzed in the powder or the granulated material is quantitatively analyzed, it is possible to perform nondestructive measurement of the object to be analyzed. Therefore, it is possible to collect and effectively utilize the analysis object subjected to the measurement. Further, unlike the preparation of a wet decomposition solution by alkali melting determined by the method for examining sediment or the like, no waste liquid or the like is generated after the wet decomposition, so that there is no need to perform these post-treatments.

  Furthermore, according to the quantitative analysis device and the quantitative analysis method of the element in the powder or the granulated material of the present invention, the analysis object using the thermal neutron transmission amount measured by the thermal neutron transmission measurement device and the method of the present invention. Analyze the concentration of the element to be analyzed in the analyte, using data with reduced measurement errors caused by uneven distribution and particle size variation of the analyte in the analyte, and data obtained with high measurement sensitivity. Quantitative analysis can be performed. Therefore, it is possible to perform quantitative analysis with high precision and high accuracy, and furthermore, expand a quantifiable region to a lower concentration range.

It is a front view showing an example of an embodiment of a thermal neutron permeation measuring device of the present invention, and is a figure showing a sample holder and a case as a sectional view. FIG. 2 is an external view of a thermal neutron transmission amount measuring device used in an example. It is an enlarged view of a neutron source. It is a flow figure showing an example of an embodiment of a quantitative analysis method of the present invention. It is a block diagram showing an example of an embodiment of a quantitative analysis device of the present invention. FIG. 4 is a block diagram illustrating an example of a means for calculating a boron concentration. FIG. 4 is a diagram illustrating a relationship between an outer diameter of a sample holder and a lower detection limit of boron. FIG. 4 is a diagram illustrating a relationship between a rotation speed of a sample holder and a lower limit of boron detection. It is a figure which shows the relationship between a measurement time and a boron detection lower limit. FIG. 4 is a diagram illustrating a rotation mechanism of a sample holder of the thermal neutron transmission measuring device used in the example.

  Hereinafter, an example of an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

1. Thermal neutron transmission rate measuring apparatus and method The thermal neutron transmission rate measuring apparatus and method of the present invention require a powder or a granulated substance as an analysis target and are required for quantitative analysis of an analysis target element concentration of the analysis target. Used for measuring thermal neutron transmission. Specifically, it is suitably used, for example, for measuring the amount of thermal neutron permeation required for quantitative analysis of the boron concentration in coal ash.

The thermal neutron transmission amount measurement method of the present invention includes an outer cylinder, an inner cylinder concentrically arranged in the outer cylinder, and a bottom plate that closes between one end of the outer cylinder and one end of the inner cylinder. The thermal neutrons are incident on one of the outer peripheral surface of the outer cylinder of the outer cylinder and the inner peripheral surface of the inner cylinder of the sample holder in which the object is accommodated, and the thermal neutrons transmitted through the analyte and released from the other are This step includes detecting the incident position of thermal neutrons or the detected position of thermal neutrons relative to the sample holder in the circumferential direction of the sample holder so as to rotate and scan the analyte in the circumferential direction of the sample holder. and to perform while changing to.

The thermal neutron transmission measurement method of the present invention is carried out, for example, using the thermal neutron transmission measurement apparatus of the present invention. The thermal neutron transmission measuring device of the present invention is a device for measuring a thermal neutron transmission amount of an analysis target using a powder or a granulated substance as an object to be analyzed, and an outer cylinder and a concentric circle in the outer cylinder. An inner cylinder that is disposed, a bottom plate that closes between one end of the outer cylinder and one end of the inner cylinder, a sample holder in which an analyte is stored, a neutron source that emits fast neutrons, and a fast neutron Moderator for converting to thermal neutrons, a detector for detecting thermal neutrons, and at least a rotating mechanism, one of the neutron source and the detector is arranged to face the inner peripheral surface of the inner cylinder, and the other Is arranged facing the outer peripheral surface of the outer cylinder, the neutron source is surrounded by the moderator, and the neutron source or detector arranged facing the outer peripheral surface of the outer cylinder is attached to the sample holder by the rotation mechanism. On the other hand, the measurement is performed by relative rotation in the circumferential direction of the sample holder .

  FIG. 1 shows an example of an embodiment of a thermal neutron transmission amount measuring apparatus according to the present invention. The thermal neutron transmission measuring device 20 shown in FIG. 1 roughly includes a sample holder 21 in which an object to be analyzed is accommodated, a neutron radiation source 23 that emits fast neutrons, and a moderator that converts fast neutrons into thermal neutrons. 22, a detector 26 for detecting thermal neutrons, and a rotating mechanism 27.

  In the present embodiment, thermal neutrons are made incident on the inner peripheral surface of the inner cylinder 21b of the sample holder 21 in which the analysis target is accommodated, and transmitted through the analysis target and released from the outer peripheral surface of the outer cylinder 21a. The case where neutrons are detected will be described as an example. Therefore, the neutron source 23 is arranged to face the inner peripheral surface of the inner cylinder 21b of the sample holder 21, and the detector 26 is arranged to oppose the outer peripheral surface of the outer cylinder 21a.

  The sample holder 21 is a container for accommodating a powder or a granulated material to be analyzed and for performing a thermal neutron transmission measurement, and includes an outer tube 21a and an inner tube arranged concentrically in the outer tube 21a. It is provided with a cylinder 21b and a bottom plate 21c that blocks between one end of the outer cylinder 21a and one end of the inner cylinder 21b. Thereby, an annular sample accommodation space is formed. The outer cylinder 21a, the inner cylinder 21b, and the bottom plate 21c are made of a material that does not substantially absorb thermal neutrons, in other words, a material having a very small thermal neutron absorption cross-sectional area, such as a resin, stainless steel, or an aluminum alloy. In the sample holder 21, a powder or a granulated substance to be analyzed is stored as it is and used for measurement. That is, in the present invention, not only does not require a complicated and time-consuming preparation and the like, such as the preparation of a wet decomposition solution by alkali melting determined by the sediment survey method or the like, for the analyte. There is also an advantage that pressure molding or the like of the analyte is not required.

The neutron source 23 emits fast neutrons in all directions. For example, a californium 252 ( ²⁵² Cf) neutron standard sealed source can be used. Here, the neutron source 23 must have a standard capacity (10 MBq) or less defined by laws and regulations. As a result, it is possible to receive design authentication as an authentication device with a display, and it is possible to easily handle the neutron source 23. In the present embodiment, the neutron source 23 is held and used by the neutron source holder 23a (see FIG. 3).

  The moderator 22 is a member that decelerates fast neutrons emitted from the neutron beam source 23 and converts them into thermal neutrons. The time required for decelerating fast neutrons is short, and an element having a small atomic number with a small neutron absorption effect is used. For example, a member made of a material containing a hydrogen element can be used as appropriate. Examples of such a material include a resin such as a polyethylene resin, a polypropylene resin, and an acrylic resin (for example, polymethyl methacrylate). Since the resin is excellent in processability and moldability, there is an advantage that a resin having a desired shape can be easily obtained and manufactured. Here, it is particularly preferable to use a polyethylene resin among the resins. Since a large amount of hydrogen element is contained in polyethylene molecules, fast neutrons can be converted to thermal neutrons very efficiently. Therefore, the efficiency of converting fast neutrons into thermal neutrons can be improved, and the number of thermal neutrons incident on the sample holder 21 can be increased, thereby improving the measurement sensitivity. Note that the moderator 22 is not limited to a resin, and for example, a container is filled with a liquid having a fast neutron moderating action, such as a liquid containing a hydrogen element such as heavy water or water, to obtain a moderator. You can also. Further, a gas having a fast neutron moderating action can be filled in a container to be used as a moderator. When a solid such as a resin is used as the moderator, the moderator is not limited to the block-shaped one, and powder or granular material may be contained in a container to be used as the moderator.

  The neutron source 23 is arranged to face the inner peripheral surface of the inner cylinder 21b of the sample holder 21. Further, the neutron source 23 is surrounded by the moderator 22. Therefore, fast neutrons radiated in all directions from the neutron source 23 are converted into thermal neutrons in the process of propagating through the moderator 22, and the thermal neutrons are emitted from the moderator 22 with three-dimensional spread. In the present embodiment, the cylindrical moderator 22 in which the neutron source 23 is embedded is filled in the inner cylinder 21 b of the sample holder 21. In this case, the neutron source 23 and the moderator 22 can be fixed in the inner cylinder 21a with a very simple configuration. Further, since the side surface of the moderator 22 is in close contact with the inner peripheral surface of the inner cylinder 21b of the sample holder 21, the thermal neutrons emitted from the side surface of the moderator 22 are directly incident on the inner peripheral surface of the inner cylinder 21b. . Therefore, the distance from the side surface of the moderator 22 from which the thermal neutrons are emitted to the detector 26 can be reduced, the attenuation of the thermal neutrons can be suppressed, and the measurement sensitivity can be easily improved. In the following description, the surface of the moderator 22 facing the inner cylinder 21b (the side surface of the moderator 22) may be referred to as the "measuring line emission surface of the moderator 22".

  The thickness of the moderator 22 disposed between the neutron source 23 and the inner peripheral surface of the inner cylinder 21b of the sample holder 21 is such that fast neutrons emitted from the neutron source 23 are sufficiently converted into thermal neutrons. And the thickness is set so as not to excessively extend the moving distance of the thermal neutrons. Thereby, while sufficient thermal neutrons are generated, the attenuation of thermal neutrons can be suppressed, and the measurement sensitivity can be easily improved. When the moderator 22 is made of a block made of polyethylene resin, for example, the thickness (the shortest path from the fast neutron incidence part to the measurement line emission surface of the moderator 22) is 20 mm to 55 mm, preferably 20 mm to 50 mm. It is more preferably from 30 mm to 50 mm, even more preferably from 40 mm to 50 mm. As for the diameter of the inner cylinder 21b of the sample holder 21, the thickness of the moderator 22 can sufficiently convert fast neutrons radiated from the neutron source 23 into thermal neutrons, and a detector for the converted thermal neutrons. The travel distance up to 26 is set so that the thermal neutrons will not be attenuated due to excessive stretching.

  Here, the thickness in the horizontal direction of the analysis object accommodated in the sample holder 21 is fixedly defined by the inner cylinder 21b and the outer cylinder 21a of the sample holder 21. Therefore, when thermal neutrons enter the inner peripheral surface of the inner cylinder 21b of the sample holder 21 and are emitted from the outer peripheral surface of the outer cylinder 21a as in this embodiment, the thermal neutrons are caused by the influence of the bulk density of the analyte. Variations in the travel distance of thermal neutrons in the analyte are suppressed. Therefore, it is possible to suppress a change in the thermal neutron capture rate (thermal neutron attenuation rate) of the element to be analyzed due to a change in the moving distance of the thermal neutron in the analyte, and thus to achieve a highly accurate and highly accurate thermal neutron transmission. The quantity can be measured. Briefly, it is possible to measure the thermal neutron transmission amount with high accuracy and high accuracy while suppressing the influence of the bulk density of the analyte.

  The thickness of the sample holder 21 in the direction of thermal neutron transmission (difference between the inner diameter of the outer cylinder 21a and the outer diameter of the inner cylinder 21b) is determined while ensuring a sufficient moving distance of the thermal neutrons in the object to be analyzed. Is set to a thickness that does not excessively elongate the moving distance. Thereby, while increasing the probability of collision between the analysis target element and the thermal neutron in the analysis target, the attenuation of the thermal neutron is suppressed, and the measurement sensitivity can be easily improved. If the thickness of the sample holder 21 in the direction of thermal neutron transmission is too thin, the operability when introducing an analyte into the sample holder 21 is reduced. Is preferably set. The thickness of the sample holder 21 in the thermal neutron transmission direction is preferably, for example, 20 mm to 30 mm.

Detector 26 is a device for detecting thermal neutrons can be used, for example, proportional counter (e.g. ³ He proportional counters, etc.). The detector 26 is used, for example, housed in the housing 25. The housing 25 is made of a material that does not substantially absorb thermal neutrons, in other words, a material having a very small thermal neutron absorption cross-sectional area. Examples of such a material include resin, stainless steel, and aluminum alloy. The housing 25 houses, for example, a preamplifier (not shown) for amplifying a signal obtained by the detector 26, in addition to the detector 26. The amplified signal is shaped into a waveform by a control processor (not shown) through a cable or the like, and data is accumulated. In the present embodiment, the housing 25 is a bottomed cylindrical container with a lid and is supported by the support body 40. However, the shape of the housing 25 is not limited to this. Instead, for example, a rectangular parallelepiped may be used. Further, the housing 25 may be directly mounted on the stage 30 without being supported by the support body 40 or the like.

  In the present embodiment, the detector 26 is fixed, and is arranged to face the outer peripheral surface of the outer cylinder 21 a of the sample holder 21. It is preferable that the detector 26 (housing 25) be arranged as close as possible within a range that does not collide with the sample holder 21. Thereby, the distance from the outer cylinder 21a to the detector 26 can be reduced, the attenuation of thermal neutrons from the outer cylinder 21a to the detector 26 can be suppressed, and the measurement sensitivity can be easily improved.

The rotation mechanism 27 is a mechanism for relatively rotating the detector 26 or the sample holder 21 that is disposed to face the outer peripheral surface of the outer cylinder in the circumferential direction of the sample holder 21. With this mechanism, the object to be analyzed can be rotationally scanned in the circumferential direction of the sample holder 21 and the entire object to be analyzed can be used for measurement. In the present embodiment, the rotation mechanism 27 includes a motor 27a for rotating the sample holder 21 around the central axis of the sample holder 21, a controller 27b for controlling the start and stop of the motor, the number of rotations, and the like. The rotation direction of the sample holder 21 may be clockwise or counterclockwise.

  When only the sample holder 21 is rotated around the central axis by the rotation mechanism 27 and the detector 26, the neutron source 23 and the moderator 22 are fixed, the neutrons are located between the neutron source 23 and the detector 26. The distance from the source 23 to the measurement line emission surface of the moderator 22, the distance from the neutron source 23 to the inner cylinder 21b, and the distance from the neutron source 23 to the outer cylinder 21b are independent of the rotation of the sample holder 21. It is always constant. Therefore, even if the sample holder 21 is rotated around the central axis, the measurement conditions do not change, and the entire analysis target contained in the sample holder 21 can be measured under the same measurement conditions.

  Here, in the present embodiment, since the cylindrical moderator 22 having the neutron source 23 embedded therein is filled in the inner cylinder 21b of the sample holder 21, the rotation of the sample holder 21 and the moderator 22 and The rotation of the neutron source 23 occurs simultaneously. In such a case, it is preferable that the neutron source 23 be disposed on the central axis of the sample holder 21. By disposing the neutron source 23 on the central axis of the sample holder 21, the distance from the neutron source 23 to the measurement line emission surface of the moderator 22, the distance from the neutron source 23 to the inner cylinder 21 b, and the neutron beam The distance from the source 23 to the outer cylinder 21b can be constant on a plane perpendicular to the central axis of the sample holder 21 in any normal direction of the peripheral surface of the sample holder 21. Therefore, even if the sample holder 21 is rotated around the central axis, the measurement conditions do not change, and the entire analysis target contained in the sample holder 21 can be measured under the same measurement conditions. When the cylindrical moderator 22 having the neutron source 23 embedded therein is filled in the inner cylinder 21 b of the sample holder 21 as in the present embodiment, the moderator 22 is rotated by the rotating mechanism 27. By rotating, the sample holder 21 can also be rotated.

  As described above, the analysis target is rotated and scanned in the circumferential direction of the sample holder 21 to provide the entire analysis target for measurement, and the entire analysis target is measured under the same measurement conditions, thereby enabling the analysis target to be analyzed. Measurement errors caused by uneven distribution of elements and variation in particle diameter can be suppressed. Further, by performing the measurement by rotating and scanning the object to be analyzed in the circumferential direction of the sample holder 21, the measurement sensitivity can be improved as compared with the case where the measurement is performed in a stopped state without performing the rotation operation. By forming the moderator 22 in a cylindrical shape, an effect of suppressing scattering and reflection of fast neutrons and decelerated thermal neutrons emitted from the neutron source 23 can be expected. This effect can also be achieved by the cylindrical shape of the sample holder 21. Therefore, it is possible to measure the amount of transmitted thermal neutrons with extremely high accuracy and high accuracy.

  Here, if the rotation speed of the sample holder 21 by the rotation mechanism 27 is too low, the measurement sensitivity is reduced. Moreover, even if it is too fast, the measurement sensitivity may be saturated or the measurement sensitivity may be reduced. Therefore, the rotation speed is set so that the rotation speed is reduced as much as possible and the driving cost for the rotation mechanism 27 can be reduced within a range where sufficient measurement sensitivity can be obtained. For example, it is preferably about 2 rpm to 25 rpm, more preferably about 5 to 15 rpm, and still more preferably about 10 rpm.

  In this embodiment, the detector 26 is a proportional counter tube, and the major axis of the proportional counter tube is arranged parallel to the central axis of the sample holder 21. In this case, the largest amount of thermal neutrons that pass through the analysis target and are emitted from the outer cylinder 21a reach the proportional counter 26. Therefore, the measurement sensitivity can be easily improved. However, the arrangement of the detector 26 (proportional counter tube) is not limited to this, and the detector 26 may be appropriately inclined with respect to the center axis of the sample holder 21 as long as a desired measurement sensitivity can be obtained.

  In addition, in the present embodiment, as shown in FIG. 1, sufficient measurement sensitivity can be obtained even when the number of the proportional counter tubes 26 is one. In this case, the cost of the proportional counter tube 26 can be reduced, and the equipment cost of the thermal neutron transmission measuring device of the present invention can be significantly reduced. However, this does not necessarily deny the use of two, three or more (for example, three or four) proportional counter tubes 26.

  In addition, the amount of thermal neutron emission on the measurement line emission surface of the moderator 22 increases in a portion at the shortest distance from the neutron source 23, and decreases toward the end. When such an in-plane distribution of the thermal neutron emission amount on the measurement line emission surface of the moderator 22 is considered, the center of the detector 26 (proportional counter) in the long axis direction is a neutron of the measurement line emission surface of the moderator 22. It is preferable to arrange so as to coincide with the portion that is the shortest distance from the radiation source 23, but it may be slightly shifted. In addition, the length of the moderator 22 in the central axis direction and the length of the sample holder 21 in the central axis direction (the length of the analysis target accommodated in the sample holder 21 in the central axis direction of the sample holder 21) are determined by the detector. It is preferable that the length be longer than the length of the effective measuring section of the 26 (proportional counter) in the major axis direction. This makes it easy to improve the measurement sensitivity by using the entire effective measuring section of the proportional counter 26.

  The principle of measuring the thermal neutron transmission amount of the analyte by the thermal neutron transmission amount measuring apparatus configured as described above will be described below.

  Fast neutrons emitted in all directions from the neutron source 23 are converted into thermal neutrons in the process of propagating through the moderator 22, and the thermal neutrons are emitted from the moderator 22 with three-dimensional spread. Of these, thermal neutrons emitted from the measurement line emission surface of the moderator 22 are incident on the inner cylinder 21b and propagate through the analysis object accommodated in the sample holder 21. In this process, some of the thermal neutrons are absorbed by colliding with the element to be analyzed in the analyte, while thermal neutrons that do not collide with the element to be analyzed pass through the analyte and pass through the outer cylinder 21a. , And reaches the detector 26 and is detected. Thereby, the thermal neutron permeation amount depending on the concentration of the element to be analyzed in the object to be analyzed is measured. Then, in the thermal neutron transmission amount measuring apparatus of the present invention, the whole object to be analyzed is subjected to measurement by rotating and scanning the object to be analyzed in the circumferential direction of the sample holder 21. Note that the higher the concentration of the element to be analyzed in the object to be analyzed, the lower the amount of thermal neutron transmission. Conversely, the lower the concentration of the analyte element in the analyte, the greater the thermal neutron penetration.

  Here, the number of thermal neutrons measured by the detector 26 can be attenuated by the half-life of the atoms used in the neutron source 23. Therefore, it is preferable to measure the blank value at regular intervals (for example, every 24 hours) and perform calibration in consideration of the blank value. Note that the blank value is a value obtained by measuring the amount of transmitted thermal neutrons in a state where the sample is not introduced into the sample holder 21. More preferably, it is provided with a correction function for correcting the signal value in consideration of the half-life of the atoms used in the neutron beam source 23. As a result, the frequency of measuring the blank value can be reduced. Alternatively, the measurement of the blank value can be omitted.

  In addition, as for the measurement time of the thermal neutron permeation amount of the analyte by the thermal neutron permeation amount measuring apparatus of the present invention, the measurement sensitivity tends to be improved as the time is longer, but the measurement sensitivity is saturated when it is longer than a certain value. Therefore, the measurement time is set so that the measurement can be completed in as short a time as possible within a range where sufficient measurement sensitivity can be obtained.

  According to the thermal neutron permeation amount measurement apparatus according to the present invention, without the need for complicated and time-consuming preparation and the like, such as the preparation of a wet decomposition solution by alkali melting determined by the sediment survey method and the like, The amount of thermal neutron permeation required for quantitative analysis of the concentration of the element to be analyzed in the object to be analyzed can be easily and quickly measured while suppressing the influence of the bulk density of the object to be analyzed. Further, it is possible to measure the amount of transmitted thermal neutrons with high sensitivity while suppressing a measurement error caused by uneven distribution of the element to be analyzed or particle size variation of the object to be analyzed.

2. Quantitative analysis device and quantitative analysis method Regarding the quantitative analysis device and the quantitative analysis method using the thermal neutron permeation amount measurement device of the present invention, an example in which the analysis target is coal ash and the analysis target element is boron will be described below. Will be described.

  The quantitative analysis method according to the present embodiment is performed, for example, according to the procedure shown in FIG. That is, the coal ash to be analyzed is collected (S01), and the thermal neutron permeation amount of the coal ash to be analyzed is measured by the thermal neutron permeation measuring device of the present invention (S02). Then, the boron concentration of the analysis target coal ash is calculated using the simple regression function (S03). In detail, for a plurality of coal ash, the boron concentration was determined as a dependent variable, and the thermal neutron transmission measured by the thermal neutron transmission measuring device of the present invention was determined as an independent variable, and a simple regression analysis was performed. By substituting the thermal neutron permeation amount of the analysis target coal ash obtained in S02 into the simple regression function, the boron concentration of the analysis target coal ash is calculated.

  The quantitative analysis method according to the present embodiment is performed by, for example, the quantitative analysis device 1 illustrated in FIG. The quantitative analyzer 1 shown in FIG. 5 includes the thermal neutron transmission measuring device 20 of the present invention, and the thermal neutron transmission measured by the thermal neutron transmission measuring device of the present invention with the boron concentration as a dependent variable for a plurality of coal ash. Means 7 for calculating the boron concentration of the coal ash to be analyzed by substituting the amount of thermal neutron permeation of the coal ash to be analyzed into a simple regression function previously determined by performing a simple regression analysis using the amount as an independent variable. At least it should be prepared.

  In the following description, `` for a plurality of coal ash, the boron concentration is used as a dependent variable, and the thermal neutron transmission measured by the thermal neutron transmission measuring device of the present invention is used as an independent variable, and a single regression analysis is performed in advance to determine. The means 7 for calculating the boron concentration of the coal ash to be analyzed by substituting the amount of thermal neutron permeation of the coal ash to be analyzed into the simple regression function may be simply referred to as "boron concentration calculating means 7".

  The analysis target coal ash collected in S01 is introduced into the sample holder 21 of the thermal neutron transmission measurement device 20, and the thermal neutron transmission is measured (S02).

  The boron concentration calculating means 7 calculates the boron concentration of the coal ash to be analyzed using a simple regression function (S03).

  The simple regression function can be obtained by the following procedure.

  First, a plurality of coal ash is prepared as a sample of the same kind as the coal ash to be analyzed. For the coal ash whose boron concentration is unknown, for example, a method for determining boron by a sediment survey method (Ministry of the Environment, Environmental Management Bureau, Water Environment Department: “About the sediment survey method”, 120725002, (2012).) Or by performing ICP (inductively coupled plasma) emission spectroscopy after bomb decomposition with nitric acid and hydrofluoric acid to obtain the boron concentration.

  In addition, it is preferable that a plurality of coal ash be prepared, for example, for each business establishment where coal ash is discharged, and used for determining a simple regression function. Thus, the quantitative analysis of the boron concentration of the coal ash discharged from the business site can be performed with higher accuracy and higher accuracy. Further, when the coal type of the coal to be traded is changed at the business establishment, it is preferable to prepare a plurality of coal ashes after the change of the coal type and use it for determining the simple regression function.

  Next, the thermal neutron transmission amount of the plurality of coal ash is measured using the thermal neutron transmission amount measuring device 20.

  Finally, a simple regression analysis is performed on multiple coal ash with boron concentration as the dependent variable and thermal neutron penetration as the independent variable. As a result, a simple regression function is obtained.

  In S03, the thermal neutron permeation amount of the analysis target coal ash obtained in S02 is substituted into the simple regression function obtained in advance in the above procedure, and the boron concentration of the analysis target coal ash is calculated.

The boron concentration calculating means 7 is, for example, a computer 10 shown in FIG. 6, and the computer 10 executes a quantitative analysis program.
The computer 10 executes a quantitative analysis program 17.

  The computer 10 includes a control unit 11, a storage unit 12, an input unit 13, a display unit 14, and a memory 15, and is mutually connected by a signal line such as a bus. Further, a data server 16 as a storage device is connected to the computer 10 by a signal line such as a bus, and transmission and reception of signals such as data and control commands (that is, input / output) are mutually performed through the signal line. Done.

  The control unit 11 controls and calculates the entire computer 10 by the quantitative analysis program 17 stored in the storage unit 12, and is, for example, a CPU (Central Processing Unit).

  The storage unit 12 is a device that can store at least data and programs, and is, for example, a hard disk.

  The memory 15 is a memory space that is a work area when the control unit 11 executes various controls and calculations, and is, for example, a RAM (Random Access Memory).

  The input unit 13 is an interface for giving at least an operator's command and the like to the control unit 11, and is, for example, a keyboard, a touch panel, or the like.

  The display unit 14 draws and displays characters, figures, and the like under the control of the control unit 11, and is, for example, a display.

  In the first embodiment, the thermal neutron permeation amount of the analysis target coal ash obtained in S02 is stored (saved) in the data server 16. The data acquired in S02 may be recorded on the data server 16 by an operator after being stored in an appropriate recording medium, for example, or may be wireless or wired from the thermal neutron transmission amount measuring device 20. The data may be automatically recorded in the data server 16 via the communication unit.

  The control unit 11 of the computer 10 includes a data reading unit 11a and a calculation unit 11b.

  When the quantitative analysis program 17 is executed, first, the data reading unit 11a of the control unit 11 reads the data acquired in S02 from the data server 16 as a storage device.

  Specifically, the data reading unit 11a reads the thermal neutron permeation amount of the analysis target coal ash acquired in S02 and stored in the data server 16 from the data server 16, and reads the thermal energy of the read analysis target coal ash. The data of the neutron transmission amount is stored in the memory 15.

  The arithmetic unit 11b of the control unit 11 calculates the boron concentration of the analysis target coal ash from the read thermal neutron transmission amount data of the analysis target coal ash and the simple regression function. Specifically, the data of the thermal neutron transmission amount of the coal ash to be analyzed is substituted into the simple regression function, and the boron concentration of the coal ash to be analyzed is calculated. The simple regression function is defined in advance in the quantitative analysis program 17.

  The data of the thermal neutron transmission amount of the coal ash to be analyzed is input by the operator via the input unit 13 when the calculation unit 11b of the control unit 11 calculates the boron concentration of the coal ash to be analyzed. You may. Alternatively, the data of the thermal neutron permeation amount of the coal ash to be analyzed may be stored in the storage unit 12 as a data file in which the data is recorded.

  According to the quantitative analysis device and the quantitative analysis method according to the present embodiment, since the quantitative analysis is performed using the thermal neutron transmission amount measured by the thermal neutron transmission measurement device of the present invention, sediment survey Simple and quick, high-accuracy and high-accuracy boron concentration in coal ash without the need for complicated and time-consuming preparations such as the preparation of wet decomposition solutions by alkali melting specified by the method, etc. Quantitative analysis becomes possible. Moreover, the thermal neutron permeation measured by the thermal neutron permeation measuring device of the present invention is high without measuring the bulk density of the coal ash to be analyzed because the influence of the bulk density of the analyte is suppressed. Accurate and highly accurate quantitative analysis of the boron concentration of the target coal ash can be performed. Therefore, the labor and time required for volume measurement and weight measurement required for calculating the bulk density of the coal ash to be analyzed can be saved, and extremely simple and rapid analysis can be performed.

  The above embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the spirit of the present invention.

For example, the thermal neutron transmission amount measurement device in the above embodiment, by rotating the sample holder 21, it had been to fix the detector 26, the sample holder 21 solid constant, the detector 26 the sample holder 21 it may be made to the in the circumferential direction rotation. In other words, the detector 26 may revolve in the circumferential direction of the sample holder 21. Also in this case, similarly to the case where the sample holder 21 is rotated, the analysis object can be rotationally scanned in the circumferential direction of the sample holder 21 and the entire analysis object can be used for measurement. In this case, the neutron source 23 is disposed on the central axis of the sample holder 21, and the central axis of the cylindrical moderator 22 is aligned with the central axis of the sample holder 21 so that the neutron source 23 is placed in the inner cylinder 21 b of the sample holder 21. It is preferable to store the moderator 22. Of course, the cylindrical moderator 22 may be filled in the inner cylinder 21b of the sample holder 21. With such an arrangement, the distance from the neutron source 23 to the survey line emission surface of the moderator 22, the distance from the neutron source 23 to the inner cylinder 21b, and the distance from the neutron source 23 to the outer cylinder 21b On a plane perpendicular to the central axis of the sample holder 21 in any normal direction of the peripheral surface of the sample holder 21. Thus, the detector 26 also for the sample holder 2 1 is relatively rotated in the circumferential direction of the sample holder 21 without causing fluctuations in measurement conditions, the entire analyte accommodated in the sample holder 21 in the same measurement conditions Can be measured. Therefore, also in this case, the effect of suppressing the measurement error caused by the uneven distribution of the element to be analyzed and the variation of the particle diameter of the object to be analyzed and the effect of improving the measurement sensitivity are exhibited.

Further, in the thermal neutron transmission amount measuring apparatus according to the above-described embodiment, the neutron source 23 is arranged to face the inner peripheral surface of the inner cylinder 21b of the sample holder 21, and the detector 26 is opposed to the outer peripheral surface of the outer cylinder 21a. Although the case where they are arranged is described as an example, the thermal neutron transmission amount measuring apparatus of the present invention is not limited to such a form. For example, the detector 26 may be arranged to face the inner peripheral surface of the inner cylinder 21b of the sample holder 21, and the neutron beam source 23 may be arranged to be opposed to the outer peripheral surface of the outer cylinder 21a.
In this case, only the sample holder 21 is rotated around the central axis by the rotation mechanism 27, and if the detector 26, the neutron source 23 and the moderator 22 are fixed, the position between the neutron source 23 and the detector 26 is fixed. The distance from the neutron source 23 to the measurement line emission surface of the moderator 22, the distance from the neutron source 23 to the inner cylinder 21b, and the distance from the neutron source 23 to the outer cylinder 21b are determined by the rotation of the sample holder 21. It is always constant regardless of. Therefore, even if the sample holder 21 is rotated around the central axis, the measurement conditions do not change, and the entire analysis target contained in the sample holder 21 can be measured under the same measurement conditions.
The fixed without rotating the sample holder 21, be allowed to rotate relative to the circumferential direction of the sample holder 21 against the neutron source 23 surrounded by the moderator 22 to the sample holder 2 1 per moderator 22 Good. In other words, the neutron source 23 surrounded by the moderator 22 may revolve around the sample holder 21 together with the moderator 22. Also in this case, similarly to the case where the sample holder 21 is rotated, the analysis object can be rotationally scanned in the circumferential direction of the sample holder 21 and the entire analysis object can be used for measurement. In this case, it is preferable that the long axis of the detector (proportional counter tube) 26 be aligned with the center axis of the sample holder 21. With such an arrangement, the distance from the detector 26 to the measurement line emission surface of the moderator 22, the distance from the detector 26 to the inner cylinder 21b, and the distance from the detector 26 to the outer cylinder 21b are determined by the sample. On a plane perpendicular to the central axis of the holder 21, it can be constant in any normal direction of the peripheral surface of the sample holder 21. Therefore, even for a neutron source 23 to the sample holder 2 1 per moderator 22 is relatively rotated in the circumferential direction of the sample holder 21 without causing fluctuations in measurement conditions, the entire analyte accommodated in the sample holder 21 Measurement can be performed under the same measurement conditions.
Therefore, also in these cases, the effect of suppressing the measurement error caused by the uneven distribution of the element to be analyzed and the variation of the particle diameter of the object to be analyzed and the effect of improving the measurement sensitivity are exhibited.

  Further, in the thermal neutron transmission amount measuring apparatus in the above-described embodiment, the inner cylinder 21b constituting the sample holder 21 is arranged concentrically in the outer cylinder 21a, but the range in which the effects of the present invention are exhibited. Therefore, a deviation between the central axis of the outer cylinder 21a and the central axis of the inner cylinder 21a is allowed. Similarly, a shift of the neutron source 23 from the center axis of the sample holder 21 and a shift of the detector 26 from the center axis of the sample holder 21 are allowed.

  Further, in the thermal neutron transmission amount measuring device according to the above-described embodiment, the neutron source 23 is arranged to face the inner peripheral surface of the inner cylinder 21b of the sample holder 21, and the detector is opposed to the outer peripheral surface of the outer cylinder 21a. In the case of disposing the sample holder 21, the inner peripheral surface of the inner cylinder 21b of the sample holder 21 is covered with the moderator 22, a space is provided around the central axis of the sample holder 21 and the periphery thereof, and the neutron source 23 is disposed in the space. You may. When the detector 26 is arranged facing the inner peripheral surface of the inner cylinder 21b of the sample holder 21 and the neutron source 23 is arranged facing the outer peripheral surface of the outer cylinder 21a, the outer cylinder 21b of the sample holder 21 May be covered with a moderator 22 so that the neutron source 23 revolves around the sample holder 21 in the circumferential direction.

Further, in the thermal neutron transmission amount measuring device according to the above-described embodiment, the neutron source 23 is arranged to face the inner peripheral surface of the inner cylinder 21b of the sample holder 21, and the detector is opposed to the outer peripheral surface of the outer cylinder 21a. If you place Te, for both the sample holder 21 and the detector 26 to the sample holder 2 1 in the circumferential direction of the sample holder 21 may be caused to rotate relative to each other. Also, when the detector 26 is arranged facing the inner peripheral surface of the inner cylinder 21b of the sample holder 21 and the neutron source 23 is arranged facing the outer peripheral surface of the outer cylinder 21a, the sample holder 21 and the neutron both sources 23 may be rotated relative against the sample holder 2 1 in the circumferential direction of the sample holder 21.

Further, in the thermal neutron transmission amount measuring device according to the above-described embodiment, the neutron source 23 is arranged to face the inner peripheral surface of the inner cylinder 21b of the sample holder 21, and the detector is opposed to the outer peripheral surface of the outer cylinder 21a. when placing Te, the detector 26 by entrained as rotated relative to the circumferential direction of the against the sample holder 2 1 sample holder 21, the circumferential direction of the sample holder 21 neutron source 23 for the sample holder 2 1 May be relatively rotated. In other words, the neutron source 23 may revolve in the inner circumferential direction of the inner cylinder 21b of the sample holder 21. Also in this case, the distance from the neutron source 23 to the measurement line emission surface of the moderator 22, the distance from the neutron source 23 to the inner cylinder 21b, and the distance from the neutron source 23 to the outer cylinder 21b are determined by the sample holder. On a plane perpendicular to the center axis of the sample holder 21, it can be constant in any normal direction of the peripheral surface of the sample holder 21. Similarly, when the neutron source 23 is arranged to face the inner peripheral surface of the inner cylinder 21b of the sample holder 21 and the detector is arranged to face the outer peripheral surface of the outer cylinder 21a, the neutron source 23 is placed in the sample holder. 2 1 by entrained as rotated relative to the circumferential direction of the sample holder 21 for the detector 26 for the sample holder 2 1 in the circumferential direction of the sample holder 21 may be caused to rotate relative to each other.

  In addition, other than the coal ash to be analyzed, for example, other than the coal ash finally discharged from a coal-fired power plant, for example, a branch is provided in a pipe or the like through which the coal ash passes, and the coal ash to be analyzed is collected from the branch. You may do so. That is, means for collecting the coal ash to be analyzed during a process in a coal-fired power plant or the like may be incorporated and provided for the quantitative analysis of the present invention.

  Further, the analysis target may be a powder or a granulated substance other than coal ash. Specific examples include minerals, loosened soil samples, various materials, foods such as agar, powders or granules such as living things and wastes, and ash of these.

  The element to be analyzed is not limited to boron, and gadolinium or lithium having a large thermal neutron absorption cross section may be used as the element to be analyzed.

  Further, the analyte may be one obtained by artificially adsorbing or absorbing the element to be analyzed. For example, after adsorbing boron (or gadolinium or lithium) in water onto an adsorbent (eg, an adsorbent polymer gel or a ceramic granule) and concentrating the adsorbent, the adsorbent is used as an analyte. By subjecting to the quantitative analysis of the present invention, it is possible to quantitatively analyze boron (or gadolinium or lithium) that can be contained in water at a low concentration.

  In addition, the thermal neutron transmission measuring device 20 may be independently installed as a measuring device used for measuring the thermal neutron transmission of the analyte in the quantitative analyzer and the quantitative analysis method of the present invention. That is, as shown in FIG. 5, the thermal neutron transmission amount measuring device 20 may be independently installed without being incorporated in the quantitative analyzer 1. Then, using the data obtained by the thermal neutron transmission amount measuring device 20, for example, the computer 10 or the like may separately calculate the analysis target element of the analysis target.

  In the above-described embodiment, the data on the thermal neutron permeation amount of the coal ash to be analyzed is stored (saved) in the data server 16. Is not limited thereto, and may be stored in the storage unit 12 or may be stored (saved) in a storage device such as a hard disk connected to the computer 10. For example, the information may be stored (saved) in various storage media that can be attached to and detached from a slot of the computer 10 so that the control unit 10 can access (in other words, recognize).

  Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

[Example 1]
The measurement conditions of the thermal neutron transmission rate in the thermal neutron transmission rate measuring apparatus of the present invention were examined.

(1) Sample The concentration of boron (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity: 99.0% or more, particle size: 45 μm or less) is set to 60 to 500 mg / kg in coal ash of a single property having a known boron concentration. The sample to which the standard was added was used. Hereinafter, this sample is referred to as a “standard sample”.

(2) Experimental apparatus An apparatus having the same basic configuration as the thermal neutron transmission amount measuring apparatus shown in FIG. 1 was used. FIG. 2 shows an external view of the apparatus used in the experiment.

The neutron source 23 was N-252CE (manufactured by Eckert & Ziegler Isotope Products). The neutron source authentication device with indicator acquired design certification (certification number are as follows.), And was packed Californium 252 (252 ^Cf) in a stainless steel capsule was dispersed in a ceramic substrate It is a sealed source. The half-life of ²⁵² Cf is 2.65 years, the average neutron energy is 2.3 MeV, the nominal activity of this neutron source is 3.7 MBq, and the neutron emission number is 4.3 × 10 ⁵ n / s. The neutron source 23 was held in a neutron source holder 23a (see FIG. 3).

In the thermal neutron transmission measurement device used in this example, the correction was not performed in consideration of the half-life of ²⁵² Cf, and the study under the same conditions was performed within 24 hours.

  The moderator 22 was made of polyethylene resin and had a cylindrical shape (130 mm × φ80 mm). The neutron source 23 was arranged on the central axis of the moderator 22. Therefore, the shortest distance from the neutron source 23 to the measurement line emission surface of the moderator 22 is 40 mm.

Proportional counter ^26, 3 the He proportional counter (gas pressure: 5.0 atm, Sensitivity: 15.6cps / nv) and the. The total length of the proportional counter is 168 mm, and the length of the effective measurement portion is 127 mm. The signal obtained by the proportional counter tube 26 is amplified by a preamplifier (not shown) housed in the housing 25 together with the proportional counter tube 26, and is shaped into a waveform by a control processor (not shown) through a cable (not shown). And accumulated the data. The measurement range of the control processor is 10 kHz or less as an input pulse, the measurement time is 1 to 3600 seconds, and the number of repetitions is 1 to 999.

  The housing 25 was a stainless steel bottomed cylindrical container with a lid capable of storing the proportional counter tube 26 and the preamplifier.

  The proportional counter 26 was arranged in parallel with the central axis of the moderator 22.

The sample holder 21 was made of SUS304, and three types having different heights and outer diameters were prepared. The specifications (outer diameter x inner diameter x height) of the three types of sample holders used are shown below. Here, “outer diameter” refers to the outer diameter of the outer cylinder 21 a of the sample holder 21, and “inner diameter” refers to the inner diameter of the inner cylinder 21 b of the sample holder 21.
・ Sample holder A: φ140 × φ82 × 100mm
・ Sample holder B: φ150 × φ82 × 160mm
・ Sample holder C: φ160 × φ82 × 70mm
The thickness of the sample holder 21 in the thermal neutron transmission direction (the difference between the inner diameter of the outer cylinder 21a and the outer diameter of the inner cylinder 21b) is 25 mm for the sample holder A, 30 mm for the sample holder B, and 35 mm for the sample holder C. is there.

  The cylindrical moderator 22 was used by being housed in the inner cylinder 21b of the sample holder 21.

  As the rotation mechanism 27, a speed control motor unit (US2-26JA-A, manufactured by Oriental Motor Co., Ltd.) was attached to the lower portion of the sample holder 21, and the sample holder 21 was rotatable at a predetermined rotation speed. In this embodiment, only the sample holder 21 is rotated, and the moderator 22 (and the neutron source 23) is fixed so as not to rotate together with the sample holder 21. FIG. 10 shows a specific configuration. The moderator 22 was fixed to the stage 30 via a shaft member 40. A cylindrical clog 41 is provided below the sample holder 21. A cylindrical member with a flange 42 was attached to the shaft member 40 via a bearing 43. The moderator 22 (and the neutron source 23) is fixed by fitting the flange portion 42 a of the flanged cylindrical member 42 into the clog 41 and transmitting the rotational force of the motor to the flanged cylindrical member 42 via the gear 44. In this state, only the sample holder 21 was rotatable.

(3) Calculation method of the lower limit of boron detection In the thermal neutron transmission measurement device, the higher the boron concentration in the sample, the larger the amount of captured thermal neutrons. Therefore, the calibration curve indicating the correlation between the amount of transmitted thermal neutrons of the sample and the boron concentration has a negative slope. Therefore, the lower limit of boron detection was obtained by partially modifying the formula (ISO / CD 11843-2: “Calibration of detection Part 2: Methodology in the liner calibration”, (1994)) determined by the ISO as follows. .

Detection limit X _d is calculated by the standard deviation S _xy gradient a and the residual of the calibration curve (displacement of each point). In the neutron boron meter, since the slope of the calibration curve shows a negative value, the boron detection lower limit was obtained from the absolute value of the calculated value as shown in the following equation 1.
X _d = | (3.29S _xy / a) | (formula 1)

Further, the standard deviation S _xy, as shown in Equation 2 below, the gradient a of the calibration curve is calculated from the intercept Y _b and the total number of measurements n. In Expression 2 below, the x value in the case of the boron concentration i was _x i, a y value _{y i.
S xy = [Σ {y i} - (ax i + Y b)} 2 / (n-2)] 1/2 ··· ( Equation 2)

The lower limit of boron quantification was determined by the following equation (3).
X _d = | (10S _xy / a) | (formula 3)

(4) Influence of standard of sample holder The thermal neutron transmission amount of a standard sample was measured using three types of sample holders, and a calibration curve was prepared to calculate the lower detection limit of boron. FIG. 7 shows the results. As the outer diameter of the sample holder increases, the lower detection limit tends to increase. When the sample holder A (outer diameter φ140 mm) is used, the lower detection limit is the lowest value (147.5 mg / kg). became.

  Here, in the present embodiment, the inner diameter of the inner cylinder of the sample holder is constant (φ82 mm), and the lower detection limit tends to increase as the outer diameter of the sample holder, that is, the diameter of the outer cylinder, increases. Therefore, it was considered that the thickness of the sample holder in the direction of thermal neutron transmission was preferably in the range of 20 mm to 30 mm, and particularly preferably about 23 mm to 27 mm.

(5) Influence of rotation speed of sample holder In order to suppress measurement errors due to uneven distribution of boron contained in the coal ash sample, thermal neutrons of the standard sample were used when the sample holder A was used and the rotation speed was 0 to 25 rpm. The amount of permeation was measured, a calibration curve was prepared, and the lower limit of detection of boron was calculated. FIG. 8 shows the results. In the range of 0 to 10 rpm, the lower detection limit tended to decrease as the rotation speed increased, and the lower detection limit at a rotation speed of 10 rpm was 156.5 mg / kg. On the other hand, when the rotation speed was increased beyond 10 rpm, the lower detection limit tended to slightly increase.

(6) Influence of measurement time Based on the results of the above (4) and (5), when the sample holder A is used and the rotation speed of the sample holder is 10 rpm, the detection lower limit value in the range of the measurement time 1 to 10 minutes is determined. Calculated. FIG. 9 shows the results. As the measurement time became longer, the lower limit decreased and tended to be substantially constant after 5 minutes or more. The lower limit of detection when the measurement time was 5 minutes was 156.4 mg / kg.

(7) Summary From the above results, quantitative analysis of boron in coal ash can be performed at the lower detection limit of 156.4 mg / kg by using the apparatus and method for measuring thermal neutron transmission of the present invention. It turned out to be possible.

DESCRIPTION OF SYMBOLS 1 Quantitative analyzer 7 Boron concentration calculation means 10 Computer 20 Thermal neutron permeation measuring device 21 Sample holder 21a Outer cylinder 21b Inner cylinder 21c Bottom plate 22 Moderator 23 Neutron radiation source 25 Housing 26 Detector, proportional counter 27 Rotation mechanism

Claims (4)

A device for measuring the thermal neutron permeation amount of the analysis target with the powder or granulated material as the analysis target,
A sample holder that includes an outer cylinder, an inner cylinder concentrically arranged in the outer cylinder, and a bottom plate that closes one end of the outer cylinder and one end of the inner cylinder; When,
A neutron source emitting fast neutrons,
A moderator for converting the fast neutrons to thermal neutrons,
A detector for detecting the thermal neutrons;
At least a rotating mechanism,
One of the neutron source and the detector is arranged to face an inner peripheral surface of the inner cylinder, and the other is arranged to face an outer peripheral surface of the outer cylinder,
The neutron source is surrounded by the moderator;
The outer cylinder the neutron source or the detector is disposed to face the outer peripheral surface of, the measurement is performed in relative rotation in the circumferential direction of the sample holder for the sample Hol da by the rotation mechanism A thermal neutron transmission amount measuring apparatus, characterized in that: A method for measuring a thermal neutron transmission amount of the powder or granulated material as an analysis target, and the analysis target,
A sample holder including an outer cylinder, an inner cylinder concentrically arranged in the outer cylinder, and a bottom plate closing between one end of the outer cylinder and one end of the inner cylinder; The step of causing thermal neutrons to be incident on one of the outer peripheral surface of the outer cylinder and the inner peripheral surface of the inner cylinder, and detecting the thermal neutrons transmitted through the analyte and emitted from the other,
In the step, the incident position of the thermal neutron or the detection position of the thermal neutron is relative to the sample holder in the circumferential direction of the sample holder so as to rotate and scan the analysis target in the circumferential direction of the sample holder. A method for measuring the amount of transmitted thermal neutrons, wherein the method is performed while changing the temperature. An apparatus for quantitatively analyzing the concentration of the element to be analyzed in the object to be analyzed, wherein the powder or the granulated substance is the object to be analyzed, and boron, gadolinium or lithium is the element to be analyzed,
A thermal neutron transmission measurement device according to claim 1,
For a plurality of samples of the same kind as the analyte, the concentration of the element to be analyzed as a dependent variable, the thermal neutron transmission measured by the thermal neutron transmission measuring device as an independent variable, and a single regression analysis is performed in advance. Means for calculating the concentration of the element of the analyte in the analyte, based on the determined simple regression function and the thermal neutron transmission of the analyte,
An apparatus for quantitatively analyzing an element in a powder or a granulated material, comprising at least: A method for quantitatively analyzing the concentration of the element to be analyzed in the object to be analyzed, wherein the powder or the granulated substance is the object to be analyzed, and boron, gadolinium or lithium is the element to be analyzed,
Measuring the thermal neutron transmission rate of the analyte by the thermal neutron transmission rate measurement method according to claim 2,
For a plurality of samples of the same kind as the analyte, the concentration of the element to be analyzed as a dependent variable, the thermal neutron transmission measured by the thermal neutron transmission measurement method as an independent variable, and a single regression analysis is performed in advance. A step of calculating the concentration of the element to be analyzed in the analyte based on the determined simple regression function and the thermal neutron transmission amount of the analyte,
A method for quantitative analysis of elements in a powder or a granulated material, characterized by comprising: