JP2008089310A - Radiation measuring apparatus and its measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently measure the intensity of radiation of neutrons etc. by a simple constitution. <P>SOLUTION: A radiation measuring apparatus 10 comprises a measuring container 14 in which a measuring chamber 13 for installing an object to be measured 11 is formed; an ionizing particle generating means 15 installed in the measuring chamber 13 for generating ionizing particles in reaction to neutrons; a support means 16 to which ionizing particles have adhered; a gas cleaning means 17 for removing ions in gases flowing in the measuring chamber 13; an ion collection means 21 for guiding ion pairs generated by the ionization of generated ionizing particles with gases in the measuring chamber 13; a power supply means 23 for supplying electric power for an electrode 22 of the ion collecting means 21; a current measuring means 24 for measuring ions collected at the ion collecting means 21 as a current; a data processing means 25 for processing data of measured current values and measuring the intensity of neutrons on the basis of a conversion constant; and a gas transport means 21 for transporting gases in the measuring chamber 13 to the ion collecting means 21. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radiation measurement technique for measuring radiation emitted from a radiation measurement object by current measurement using an ionization action by radiation, and more particularly, radiation that is capable of efficiently measuring radiation such as neutrons and simplified radiation. The present invention relates to a measuring apparatus and a measuring method thereof.

  In general, this type of radiation measuring apparatus has an ion pair formed by ionizing a gas in the vicinity thereof by radiation emitted from a measurement object, and the generated ions have a lifetime of several seconds to several tens of seconds. Exists in the vicinity of the measurement object. Since the number of ions of the ion pair generated by the ionizing action by radiation is proportional to the intensity of the radiation, the intensity of the radiation can be obtained by measuring the number of ions generated.

As this type of radiation measuring apparatus, there are neutron detectors such as a BF ₃ proportional counter, a boron-coated proportional counter, and a ³ He proportional counter.

The BF ₃ proportional counter is a neutron detector utilizing the fact that the cross-sectional area of the (n, α) reaction between ¹⁰ B and thermal neutrons is large, and this neutron detector 1 is formed in a metal cylinder 2 as shown in FIG. Is filled with BF ₃ gas, and the center core wire 3 is supported via the insulators 4a and 4b with the cylinder 2 as a cathode, and an electrode structure is formed with an anode.

The neutron detector 1 has a manufacturing example of a metal cylinder having a diameter of 15 cmφ and a length of 180 cm, but generally has a diameter of 2.5 cmφ and a length of several tens of cm. Therefore, when a large neutron detector is required, a combination of a plurality of commercially available BF ₃ proportional counters having a diameter of 2.5 cmφ and a length of several tens of cm is used.

In addition, the boron-coated proportional counter is a ¹⁰ B (B-10) thin film coated on the inner surface of a cylinder, and is an ionizable particle (charged particle) of ⁷ Li and α particles generated by the reaction of ¹⁰ B with neutrons. When the gas runs through the gas, it is ionized to generate an electrical signal, and this electrical signal is measured to detect neutrons. Since neutrons have no charge, they are indirectly counted by measuring ionizing particles (charged particles) generated by some nuclear reaction.

The boron-coated proportional counter as a neutron detector is a metal cylindrical inner surface coated with boron (B), and the ³ He proportional counter is a recoil using the (n, p) reaction of ³ He and thermal neutrons. Proton proportional counters, both neutron detectors have the same challenges as BF ₃ proportional counters.

  Moreover, there exists a thing shown by patent document 1 as this kind of a radiation measuring apparatus. As shown in FIG. 10, the radiation measuring apparatus a stores an object to be measured d in a measuring chamber c in a measuring container b, and an ion detector g as an ion collecting means in which a voltage is applied to an electrode e by a power source f. The current measuring means h for measuring the ions collected by the ion detector g as current, and the gas transport means (suction means) j for transporting the gas inside the measurement chamber c to the ion detector g through the transport pipe i. Is done. In the radiation measurement apparatus a, gas is ionized by radiation emitted from a radiation source accommodated in the measurement object d, and ions are generated.

The gas in the measurement chamber is sucked to the ion detector g by the gas transport means j, transferred together with the ions in the gas, collected by the electrodes, and measured as a current value by the current measurement means h. In addition, the code | symbol k is a data processing means, and the code | symbol 1 is a gas purification means.
JP 2006-105882 A JP 2006-46972 A JP 2005-134239 A JP 2004-239762 A

  In the radiation measuring apparatus a described in Patent Document 1, when the measurement object d has a short dimension, for example, if it is 1 m or less, the measurement object can be stored in the measurement chamber. In the case of a measurement object having a length of several meters such as a fuel rod or a large measurement object that cannot be installed in the measurement chamber c, there is a problem that measurement cannot be performed.

Further, in a radiation measuring apparatus that employs a BF ₃ proportional counter or the like as a conventional neutron detector, ionizing particles generated by a reaction with thermal neutrons, for example, (n, α) reaction, pass through the gas. Ions generated by running and ionizing were collected by the electric field of the generator.

  In the conventional radiation detection apparatus, the reaction place with thermal neutrons and the ion collection place of the electric field are the same place. In addition, in order to collect ions efficiently, a strong electric field is required. When the diameter of the metal cylinder is increased, it is necessary to maintain the strength of the electric field and increase the voltage applied between the electrodes.

  However, since the voltage applied between the electrodes is limited by the withstand voltage of the insulating material that holds the electrodes, there is a dimensional limitation in increasing the size of the radiation detection apparatus.

  The present invention has been made in consideration of the above-described circumstances, and can efficiently and efficiently measure the intensity of radiation such as neutrons emitted from a measurement object with a simple configuration. An object of the present invention is to provide a radiation measuring apparatus and a measuring method thereof.

  In order to solve the above-described problems, a radiation measurement apparatus according to the present invention is a measurement container in which a measurement chamber in which a measurement object is placed is formed, and is installed in the measurement chamber to generate ionizable particles by reacting with neutrons. The support means to which the means is attached, the gas purification means for removing ions in the gas flowing into the measurement chamber, and the ions generated by ionization of the generated ionizing particles together with the gas in the measurement chamber Ion collection means to be guided, power supply means for supplying power to the electrodes of the ion collection means, current measurement means for measuring ions collected by the ion collection means as current, and measured current values as data Data processing means for processing and measuring neutrons from a conversion constant of neutron intensity, and gas transport means for transporting the gas in the measurement chamber to the ion collecting means It is characterized in that.

  Moreover, in order to solve the above-described problem, the radiation measurement method according to the present invention provides a (n, α) reaction between a neutron emitted from a measurement object and ionizing particle generation means, and (n, p). At least one kind of reaction and (n, f) reaction generates ionizable particles, and the generated ionizable particles ionize the gas in the measurement chamber to generate ion pairs. It is a method characterized in that ions collected by transporting to an ion collecting means are measured as a current or an electric quantity, and the intensity of radiation is measured from the current value using a conversion constant.

  The radiation measuring apparatus and the measuring method according to the present invention can efficiently and efficiently measure the radiation intensity of neutrons and the like emitted from the measurement object with a simple configuration.

  Embodiments of a radiation measuring apparatus according to the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a schematic configuration diagram showing a first embodiment of a radiation measuring apparatus according to the present invention.

The radiation measurement apparatus 10 shown in FIG. 1 measures neutron measurement that measures, for example, ²³⁸ U or ²⁴⁰ Pu spontaneous fission neutrons or neutrons generated by (α, n) reaction between α-rays and light elements such as oxygen. It is a device, and is a neutron measurement device that measures neutrons from the measurement object 11. The measurement object 11 includes a radiation source 12 that emits neutrons.

This radiation measurement apparatus 10 is installed in a measurement chamber 14 as a main body casing in which a measurement chamber 13 that houses a measurement object 11 is formed, and in the measurement chamber 13, and generates ionizable particles by, for example, (n, α) reaction. The ionizing particle generating means 15 such as ¹⁰ B (B-10), the supporting means 16 attached with the ionizing particle attaching means 15, and the gas purifying means 17 for removing ions in the gas flowing into the measurement chamber 13. Generated by a reaction between an installation table (base) 18 provided with a measurement object 11 that emits radiation in the measurement chamber 13 and ionizing particle generation means 15 by radiation from the measurement object 11 including the radiation source 12. The ionized particles are ionized to form ion pairs, and the ion pairs are squeezed and guided together with the gas in the measurement chamber 13, and the gas converging means 20 is guided together with the gas. Ion collection means 21 having a narrow gas passage cross-sectional area for guiding the ion pair, power supply means 23 for supplying power to the electrode 22 of the ion collection means 21, and current measurement for measuring ions collected by the ion collection means 21 as current Means 24, data processing means 25 for processing data of the measured current value, gas transport means 26 for transferring the gas in the measurement chamber 13 to the ion collecting means 21 through the gas converging means 20, and the ion collecting means 21. It is comprised from the gas purification means 27 which purifies the gas which passed.

  The ion collecting means 21 is provided with a core wire 29 constituting the anode 22 in the center of a metal cylinder 28 such as stainless steel constituting the cathode, and is transported together with gas from the measurement chamber 13 to the electrode 22 of the core wire 29. Ions are collected. Note that the gas that has passed through the ion collecting means 21 may be guided by the gas transport means 26 to the gas purification means 17 through a gas circulation path (not shown), and the ions may be removed and guided into the measurement chamber 13. In this case, installation of the gas purification means 27 becomes unnecessary.

Further, the ionizing particle generating means 15 of the radiation measuring device ^10, 10 B in addition to (B-10), thermal neutrons and (n, t) reaction ⁶ Li and cause (n, p) reacts example ³ For example, Th, U, Pu and their isotopes may be used to cause a He, (n, f) reaction.

The ionizing particle generating means 15 is made of, for example, ¹⁰ B, and is applied and mounted on the surfaces of a pair of stainless steel support plates 16a and 16b constituting the support means 16. The ionizable particle generating means 15 (15a, 15b) is configured by applying a thin film, for example, a ¹⁰ B film on the surface of the support means 16. The ion collection means may be structured to collect in a bell mouth shape or a trumpet shape.

  Next, the operation of the radiation measuring apparatus 10 will be described.

Neutrons emitted from the radiation source 12 of the measurement object 11 are decelerated by the measurement object 11 and surrounding objects to become thermal neutrons. When the ionizable particle generating means 15 is ¹⁰ B, the thermal neutron emits excited ⁷ Li, α particles according to the following reaction formula.

[Chemical 1]
¹⁰ B + n → ⁷ Li ^* + ⁴ He ^* 2.31 MeV
Here, ⁷ Li has an energy of 0.84 MeV, and α particles have an energy of 1.47 MeV, so that the ionizing particles having these energies are not lost inside the ionizing particle generating means 15 generated. The particle generating means 15 is composed of a ¹⁰ B thin film applied to the surface of the supporting means 16.

  The ionizing particles generated by the ionizing particle generating means 15 ionize the gas in the measurement chamber 13 to generate ion pairs. The generated ions have a lifetime of several seconds to several tens of seconds and coexist with the gas in the measurement chamber 13.

Here, since the W value of the air of α particles is 35.1 eV, when the generated ion pair is estimated using this value, 50% of the energy 2.31 MeV generated by the above reaction formula is converted into the ionization of the air. Assuming that it contributes, about 33000 ion pairs are generated. When this ion pair is converted into electric charge, it becomes 5.3E-15C (5.3 × 10 ⁻¹⁵ C). This charge conversion energy is a charge generated per reaction of one ion pair. Two reactions result in 12-14C, and this level can be measured electrically with an electrometer. Usually, since a plurality of reactions are targeted, the level is sufficiently measurable.

  In this radiation measurement apparatus 10, ions generated in the measurement chamber 13 by neutrons emitted from the radiation source 12 included in the measurement object 11 are gas in the measurement chamber 13 by the gas transport means 26 as suction means. At the same time, it is transported to the ion collecting means 21 through the gas converging means 20.

  Ions contained in the gas while passing through the ion collecting means 21 are collected by the electrode (anode) 22 and measured as a current value by the current measuring means 24. The current measuring unit 24 is, for example, an electrometer.

  Here, if the radiation source 12 included in the measurement object 11 is a radiation source that emits only neutrons, the current measurement unit 24 measures the current when the measurement object 11 does not exist in the measurement chamber 13 in advance, This current value is set as a background current value.

  When the measurement object 11 is in the measurement chamber 13, the current value measured by the current measuring unit 24 is set as the gross current value, and the background current value is subtracted from the gross current value by the data processing unit 25. This subtraction value is calculated as a net current value. The net current value is measured, and the neutron intensity can be easily obtained from the net current value by using a conversion constant of neutron intensity.

  According to the radiation measuring apparatus 10 shown in FIG. 1, the measurement chamber 13 and the ionizing particle generating means 15 do not need an electric field at the ionizing particle generation location. The size can be increased according to the neutron detection efficiency.

  On the other hand, in this radiation measuring apparatus 10, since the ionization particle production | generation place produced | generated by the nuclear reaction with neutron and the gas in the measurement champ 13 are ionized, the ion collection place collected can be separated. The size of the ion collecting means 21 can be reduced without making it the same as that of the measurement chamber. Even if the device is downsized, the ion collecting means 21 can be manufactured to a size that can generate an electric field having an appropriate strength.

  When a neutron measurement device with high neutron measurement efficiency is required as the radiation measurement device 10, neutron measurement efficiency can be improved with one large neutron detector without using a combination of many small neutron detectors. . Further, even if a large neutron detector is employed, the ion collecting means 21 can be made smaller than the conventional radiation detection device without increasing the size, and therefore, neutrons can be measured with high efficiency with a simple configuration.

[Second Embodiment]
FIG. 2 is a schematic configuration diagram showing a second embodiment of the radiation measuring apparatus according to the present invention.

  The radiation measurement apparatus 10A shown in the second embodiment is an apparatus that measures a neutron by installing a measurement object 11 including a radiation source 12 that emits neutrons outside a measurement chamber 13.

  In this radiation measurement apparatus 10A, conditions such as the dimensions of the measurement chamber 13 are determined in consideration of the size and shape of the measurement object 11 so that neutrons emitted from the measurement object 11 can be detected with high sensitivity.

  In describing the radiation measurement apparatus 10A shown in the second embodiment, the same components as those in the radiation measurement apparatus 10 shown in the first embodiment are denoted by the same reference numerals, and redundant description is omitted or simplified.

A radiation measurement apparatus 10A shown in FIG. 2 is provided in a measurement container 14 in which a measurement chamber 13 is formed, a measurement object 11 provided with a radiation source 12 installed in the vicinity of the outside of the measurement chamber 13, and a measurement chamber 13. An ionizing particle generating means 15 such as ¹⁰ B (B-10) which is installed and generates ionizing particles by (n, α) reaction that reacts with thermal neutrons, and a supporting means to which the ionizing particle generating means 15 is attached. 16, gas purifying means 17 for removing ions in the gas flowing into the measurement chamber 13, ion collecting means 21 for collecting ions transported through the gas transport path 30 together with the gas ionizing particles. A power supply means 23 for supplying power to the electrode 22 of the ion collection means 21, a current measurement means 24 for measuring ions collected by the ion collection means 21 as a current, and a measured current value Data processing means 25 that performs data processing, gas transport means 26 that also serves as suction means for transporting the gas in the measurement chamber 13 to the ion collection means 21, and gas purification means 27 that purifies the gas that has passed through the ion collection means 21 Consists of. The gas transport path 30 may constitute a bell mouth-like or trumpet-like gas converging structure like gas converging means.

The ionizable particle generating means 15 is shown as an example of ¹⁰ B coated on the support plates 16 a and 16 b forming the pair of the support means 16, but the ionizable particle generating means 15 is coated on the inner surface of the measurement container 14. You may let them. Further, the uncoated surface of the support means 16 coated with the ionizing particle generating means 15 may be placed toward the inner surface of the measurement chamber 13. Further, the support means 16 coated with the ionizing particle generating means 15 may be arranged in multiple layers or in a lattice form in the measurement chamber 13 so that the gas on the surface of the ionizing particle generating means 15 flows.

  Next, the operation of the radiation measuring apparatus 10A shown in the second embodiment will be described.

In this radiation measurement apparatus 10A, neutrons emitted from the radiation source 12 of the measurement object 11 are decelerated by the measurement object 11 or surrounding objects to become thermal neutrons. This thermal neutron is incident on the inside of the measurement chamber 13 and reacts with the ionizing particle generating means 15 inside the measurement chamber 13. When the ionizing particle generating means 15 is ¹⁰ B, thermal neutron and ¹⁰ B cause (n, α) reaction (nuclear reaction), and excited ⁷ Li and α particles are released. Alpha particles are helium nuclei, consisting of two protons and two neutrons, and constitute ionizing particles.

  The generated ionizing particles ionize the gas in the measurement chamber 13, and the ion pair generated by this ionization action is gasified together with the gas in the measurement chamber 13 by the operation of the gas transport means (suction means) 26. It is transported to the ion collecting means 21 via the transport path 30. While the transported ion pair passes through the ion collecting means 21, the ions are collected on the electrode 29 and measured as a gross current value by the current measuring means 24.

  On the other hand, in the current measuring means 24, the current value measured in a state where the measurement object 11 does not exist in the vicinity of the outside of the measurement chamber 13 and the measurement object 11 does not affect the measurement chamber 13 is referred to as the background current value. To do. The data processing means 25 calculates a net current value by subtracting the background current value from the gross current value. The neutron intensity of the measurement object 11 can be obtained from the net current value and the conversion constant of the neutron intensity obtained in advance.

  In the radiation measuring apparatus 10A shown in FIG. 2, for example, even when the measurement object 11 is large and cannot be accommodated in the measurement chamber 13, the measurement chamber 13 and the ionizing particle generating means 15 are provided according to the required detection efficiency. It can be enlarged so that it can be measured. On the other hand, the size of the ion collecting means 21 can be reduced without making it the same as the size of the measurement chamber 13, and can be installed in a size / space that creates an appropriate electric field.

  According to the neutron detection efficiency required for the radiation measuring apparatus 10A, the radiation measuring apparatus 10A can be simplified and enlarged, and neutrons can be easily and highly efficiently without being combined with a plurality of neutron detectors. Can be measured.

[Third Embodiment]
FIG. 3 is a schematic configuration diagram showing a third embodiment of the radiation measuring apparatus 10B according to the present invention.

  In describing the radiation measuring apparatus 10B shown in the third embodiment, the same components as those in the radiation measuring apparatus 10 shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted or simplified.

  The radiation measurement apparatus 10 </ b> B shown in the third embodiment is a neutron measurement apparatus that stores the measurement object 11, ionizable particle generation means 15, and the neutron moderator 33 inside the measurement chamber 13 and measures neutrons.

The radiation measuring apparatus 10B includes a measuring container 14 that forms a measuring chamber 13, a measuring object 11 that is housed in the measuring chamber 13 and includes a radiation source 12, and is installed inside the measuring chamber 13 to react with thermal neutrons. For example, an ionizing particle generating means 15 such as ¹⁰ B that generates ionizing particles by an (n, α) reaction, a supporting means 16 attached with the ionizing particle generating means 15, and an inside of the measurement chamber 13. A neutron moderator 33 as a neutron moderator such as polyethylene that decelerates neutrons emitted from the measurement object 11 to generate thermal neutrons, and the neutron moderator 18 is covered to prevent charging. For example, the antistatic means of the cover 34 made of stainless steel, the gas purification means 17 for removing ions in the gas flowing into the measurement chamber 13, the thermal neutron and the charge A gas converging means 20 that narrows the gas ionized by the ion generating particles generated by the child generating means 15 to an ion collecting means 21 having a narrow gas passage cross-sectional area, and an ion that has an electrode 22 in the center and collects ions that are transported together with the gas Collecting means 21, power supply means 23 for supplying power to the electrodes 22 of the ion collecting means 21, current measuring means 24 for measuring the ions collected by the ion collecting means 21 as current, and data processing of the measured current values. Data processing means 25 to be performed, gas transport means 26 for transporting the gas in the measurement chamber 13 to the ion collecting means 21 through the gas converging means 20, and gas purifying means 27 for purifying the gas after passing through the ion collecting means 21 Composed.

  Further, the neutron moderator 33 installed in the measurement chamber 13 constitutes thermal neutron generating means for generating thermal neutrons by decelerating neutrons, and the stainless steel cover 34 prevents the neutron moderator 33 from being charged. Constitutes anti-static.

  The operation of the radiation measuring apparatus 10B shown in the third embodiment will be described.

In the radiation measuring apparatus 10 </ b> B shown in FIG. 3, neutrons emitted from the radiation source 12 of the measurement object 11 are decelerated by the neutron moderator 33 and become thermal neutrons. This thermal neutrons reach the ionizing particle generating means 15 of the transmission to ^{10 B} for example stainless steel of the support means 16, ^{10 B} is of thermal neutrons (n, alpha) ionizing particles (charged particles) by reaction Is generated.

  The generated ionizing particles ionize the gas in the vicinity of the measurement chamber 13 to generate ion pairs. The generated ions exist in the gas for about several seconds to several tens of seconds and coexist.

  The ion pairs generated inside the measurement chamber 13 by the thermal neutrons are guided and transported to the ion collecting means 21 through the gas converging means 20 together with the gas in the measurement chamber 13 by the suction action of the gas transport means 26. The ions of the guided ion pair are collected by the electrode 22 while passing through the ion collecting means 21, and the collected ions are measured by the current measuring means 24 as a gross current value.

  The gross current value measured as a current by the current measuring means 21 can be obtained by performing data processing similar to that of the first embodiment by the data processing means 25.

According to the radiation measuring device 10B shown in the third embodiment, the measurement chamber 13, 10 neutron moderator 33 such as ionizing particle generator 15 and polyethylene, such as ^B is depending on the required neutron detection efficiency Can be enlarged. On the other hand, unlike the measurement chamber 13, the ion collecting means can be miniaturized and can be set to a size that forms an appropriate electric field. Therefore, it is possible to construct a simple and simple large-sized radiation measuring apparatus without combining a large number of small neutron detectors, and this radiation measuring apparatus 10B can accurately and efficiently produce neutrons. It can be measured well.

[Fourth Embodiment]
FIG. 4 is a schematic configuration diagram showing a fourth embodiment of the radiation measuring apparatus according to the present invention.

  In describing the radiation measurement apparatus 10C shown in this embodiment, the same components as those in the radiation measurement apparatus 10 of the first embodiment are denoted by the same reference numerals, and redundant description is omitted or simplified.

  The radiation measurement apparatus 10 </ b> C shown in FIG. 4 places a measurement object 11 including a radiation source 12 outside the measurement chamber 13, and stores the ionizable particle generating means 15 and the neutron moderator 33 inside the measurement chamber 13. Neutron measuring device.

This radiation measurement apparatus 10C is installed in the measurement chamber 13 having the measurement chamber 13 installed in the vicinity of the outside without including the measurement object 11, and generates thermal neutrons by decelerating neutrons. A neutron moderator 33, a cover 34 made of, for example, stainless steel covering the periphery to prevent the neutron moderator 33 from being charged, and ¹⁰ B of ionizable particles generated by thermal neutron and (n, α) reaction. The ionizing particle generating means 15, the supporting means 16 attached with the ionizing particle generating means 15, the gas purification means 17 for removing ions in the gas flowing into the measurement chamber 13, and the ionizing particles are ionized. For example, ion collecting means 21 for collecting ions transported together with a gas such as air, power supply means 23 for supplying power to the electrode 22 of the ion collecting means 21, Current measuring means 24 for measuring the ions collected by the on-collecting means 21 as current, data processing means 25 for processing data of the measured current values, and gas transport means for transporting the gas in the measurement chamber 13 to the ion collecting means 21 And gas purifying means 27 for purifying the gas after passing through the ion collecting means 21.

  The neutron moderator 33 is made of polyethylene or the like and constitutes thermal neutron generation means, and the stainless steel cover 34 constitutes antistatic means for preventing the neutron moderator 33 from being charged.

  Next, the operation of the radiation measuring apparatus 10C will be described.

In this radiation measurement apparatus 10C, neutrons emitted from the radiation source 12 of the measurement object 11 pass through the wall of the measurement container 14, enter the inside of the measurement chamber 13, are decelerated by the neutron moderator 33, and are converted into thermal neutrons. Become. This thermal neutron undergoes a nuclear reaction with the ionizable particle generating means 15 installed in the measurement chamber 13. When the ionizing particle generating means 15 is ¹⁰ B, the thermal neutron causes (n, α) reaction with ¹⁰ B, and the ionizing particles are released. The internal gas is ionized, resulting in ion pairs. The generated ions are transported together with the gas in the measurement chamber 13 by the gas transporting means 26 and guided to the ion collecting means 21 as in the case of the first embodiment. In the ion collecting means 21, ions transported together with the gas are collected by the electrode 22, and the collected ions are measured as current by the current measuring means 24. The measured ion current value can be obtained by performing data processing in the data processing means 25 to obtain the neutron intensity.

  In the radiation measurement apparatus 10 </ b> C shown in the fourth embodiment, the measurement chamber 13, the ionizable particle generating means 15, and the neutron moderator 33 can be enlarged according to the required neutron detection efficiency. On the other hand, the size of the ion collecting means 21 can be reduced without making it the same as the size of the measurement chamber 13, and can be set to a size that creates an appropriate electric field. Therefore, according to the required neutron detection efficiency, it is possible to obtain a radiation measurement apparatus 10C that can measure neutrons easily and with high efficiency.

[Fifth Embodiment]
FIG. 5 is a schematic configuration diagram showing a fifth embodiment of the radiation measuring apparatus according to the present invention.

  In describing the radiation measurement apparatus 10D, the same components as those in the radiation measurement apparatus 10 of the first embodiment are denoted by the same reference numerals, and redundant description is omitted or simplified.

  The radiation measurement apparatus 10 </ b> D shown in FIG. 5 stores the measurement object 11 and the ionizing particle generation means 15 in the measurement chamber 13 formed in the measurement container 14, and thermal neutrons around the measurement container 14. It is a neutron measuring device provided with a neutron moderator 35 (35a, 35b, 35c) as a generating means.

The radiation measurement apparatus 10D is provided on a measurement container 14 in which a measurement chamber 13 is formed, an installation table 18 in the measurement chamber 13, a measurement object 11 including a radiation source 12, and an installation inside the measurement chamber 13. The ionizing particle generating means 5 such as ¹⁰ B that reacts with thermal neutrons to generate ionizing particles by, for example, (n, α) reaction, the support means 16 attached with the ionizing particle generating means 15, and measurement The neutron moderator 35 disposed around the chamber 13, the gas purifying means 17 for removing ions in the gas flowing into the measurement chamber 13, and the ionizing particles generated by the thermal neutrons and the ionizing particle generating means 15 are ionized. A gas converging means 20 for narrowing a gas such as air into a bell mouth shape or a trumpet shape, and a gas passage for collecting ions transported together with the gas having an electrode 22 in the center. An ion collecting means 21 having a small cross-sectional area, a power supply means 23 for supplying power to the electrode 22 of the ion collecting means 21, a current measuring means 24 for measuring ions collected by the ion collecting means 21 as a current, and a measured current Data processing means 25 for performing data processing of values, gas transport means 26 for transporting the gas in the measurement chamber 13 to the ion collecting means 21 via the gas converging means 20, and a gas for purifying the gas after passing through the ion collecting means 21 And purification means 27.

  Next, the operation of the radiation measuring apparatus 10D will be described.

  In the radiation measurement apparatus 10 </ b> D shown in FIG. 5, neutrons are emitted from the radiation source 12 of the measurement object 11 installed inside the measurement chamber 13, and the neutrons emitted from the radiation source 12 are emitted from the wall of the measurement container 14. , While being decelerated by the surrounding neutron moderator 35 to become thermal neutrons.

The thermal neutrons pass through the wall of the measurement container 14 and reach the ionizing particle generating means 15 inside the measurement chamber 13. When the ionizable particle generating means 15 is, for example, ¹⁰ B (B-10), ¹⁰ B undergoes a (n, α) reaction with thermal neutrons to generate ionizable particles.

  The ionizing particles ionize the gas in the measurement chamber 13 with ionization energy to generate ion pairs. The generated ions are sucked together with the gas in the measurement chamber 13 by the gas transport means 26 that is a suction means, narrowed down by the gas converging means 20, and transported to the ion collection means 21. Of the ion pairs transported to the ion collecting means 21, ions (anions) are positively collected by the electrode (anode) 22 of the ion collecting means 20, and the current due to the collected ions is measured by the current measuring means 24. The gross current value is calculated.

  This gross current value is compared with the background current value when there is no measurement object in the measurement chamber 13, and the data processing means 25 subtracts the background current value from the gross current value to calculate the net current value. The From this net current value, data processing using a neutron conversion constant can be performed to determine the neutron intensity.

  According to the radiation measurement apparatus 10 </ b> D shown in FIG. 5, the measurement chamber 13, the ionizable particle generating means 15, and the neutron moderator 35 can be enlarged according to the required neutron detection efficiency. On the other hand, the size of the ion collecting means 21 can be reduced without making it the same as the dimension of the measurement chamber 13, and can be set to such a size that the ion collecting means 21 creates an appropriate electric field.

  Therefore, by appropriately setting the size and shape of the measurement container 14 and the like according to the 3D dimensions of the measurement object 11, the radiation measurement apparatus 10D having a simple structure can be provided even if it is large. According to the required neutron detection efficiency, it is not necessary to use a combination of a large number of neutron detectors, and a radiation measurement apparatus 10D that can measure neutrons easily and with high efficiency is obtained.

[Sixth Embodiment]
FIG. 6 is a schematic configuration diagram showing a sixth embodiment of the radiation measuring apparatus according to the present invention.

  In describing the radiation measuring apparatus 10E, the same components as those in the radiation measuring apparatus 10 shown in the first embodiment are denoted by the same reference numerals, and redundant description is omitted or simplified.

  The radiation measuring apparatus 10E shown in the sixth embodiment installs the measurement object 11 including the radiation source 12 outside the measurement container 14, arranges a neutron moderator 35 around the measurement container 14, and measures the measurement chamber. 13 is a neutron measuring apparatus in which ionizing particle generating means 15 is housed inside 13.

This radiation measurement apparatus 10E includes a measurement container 14 in which a measurement chamber 13 is formed, a neutron moderator 35 installed around the measurement container 14, and a measurement target having a radiation source 12 installed near the outside of the measurement container 14. An ionizing particle generating means 15 such as ¹⁰ B which is installed inside the object 11 and the measurement chamber 13 and generates ionizing particles by thermal neutron and (n, α) reaction; and the ionizing particle generating means 15 The adhering support means 16, the gas purification means 17 for removing ions in the gas flowing into the measurement chamber 13, and the gas in the measurement chamber 13 such as air in which the ionizing particles are ionized pass through the gas transport path 30. The ion collection means 21 transported through the power supply, the power supply means 23 for supplying power to the electrode 22 of the ion collection means 21, and the ions collected by the ion collection means 21 as current. Current measuring means 24 for measuring the current, data processing means 25 for processing the data of the measured current value, gas transport means 26 for transporting the gas in the measurement chamber 13 to the ion collecting means 21, and after passing through the ion collecting means 21 And gas purifying means 27 for purifying the gas.

  The ion collecting means 21 is provided with an electrode (anode) 22 made of a core wire arranged concentrically at the center of a metal cylinder constituting the cathode, and a predetermined amount of power is supplied between the electrodes of the ion collecting means 21 by a power supply means 23. A voltage is applied.

In the radiation measurement apparatus 10E shown in the sixth embodiment, neutrons emitted from the radiation source 12 of the measurement object 11 are decelerated by the neutron moderator 35 (35a, 35b, 35c) around the measurement container 14 and heated. It becomes a neutron (slow neutron). This thermal neutron passes through the wall of the measurement container 14 and enters the measurement chamber 13. The incident thermal neutron collides with the ionizing particle generating means 15 to cause a nuclear reaction. When the ionizable particle generating means 15 is ¹⁰ B, the thermal neutron causes (n, α) reaction with ¹⁰ B, and the ionizable particles are released.

  The discharged ionizing particles ionize the gas inside the measurement chamber 13, and as a result, ion pairs (positive ions and negative ions) are generated. The ion pair generated in the measurement chamber 13 is transported to the ion collecting means 21 through the gas transport path 30 together with the gas in the measurement chamber 13 by the suction action of the gas transport means 26. Among the ion pairs transported to the ion collector 21, cations are collected on the electrode (negative electrode) 22 of the ion collector 21. The current due to the collected ions is measured by the current measuring means 24, and the gross current value is measured.

  The gross current value is subjected to data processing similar to that of the radiation measuring apparatus 10 shown in the first embodiment by the data processing means 25, and the net current value is calculated from the background current value calculated in advance. Using this net current value and a conversion constant to neutron intensity, the neutron intensity of the measurement object can be obtained.

  According to this radiation measurement apparatus 10E, the measurement container 14, the ionizing particle generation means 15, and the neutron moderator 35 in which the measurement chamber 13 is formed efficiently transfer the large measurement object 11 according to the required neutron detection efficiency. It can be enlarged so that it can be measured.

  On the other hand, the size of the ion collecting means 21 can be reduced without being the same as the size of the measurement chamber 13, and can be set to a size that creates an appropriate electric field. Therefore, even when the measurement object 11 and the neutron moderator 35 are not accommodated in the measurement chamber 13, the radiation measurement apparatus 10E that can measure neutrons easily and with high efficiency can be obtained.

[Seventh Embodiment]
FIG. 7 is a schematic configuration diagram showing a seventh embodiment of the radiation measuring apparatus according to the present invention.

  In describing the radiation measurement apparatus 10F of this embodiment, the same components as those of the radiation measurement apparatus 10 of the first embodiment are denoted by the same reference numerals, and redundant description is omitted or simplified.

  The radiation measurement apparatus 10 </ b> F according to the seventh embodiment is a neutron measurement apparatus that houses a measurement object 11 including a radiation source 12 inside a measurement chamber 13 and measures neutrons emitted from the measurement object 11. This neutron measurement apparatus can accurately measure neutrons even when the measurement object 11 detects, for example, α rays in addition to neutrons.

This radiation measurement apparatus 10F is installed in a measurement container 14 in which a measurement chamber 13 is formed, a measurement object 11 having a radiation source 12 installed in the measurement chamber 13, and a measurement neutron that reacts with thermal neutrons. Then, for example, an ionizable particle generating means 15 such as ¹⁰ B that generates ionizable particles by (n, α) reaction, a support means 16 attached with the ionizable particle generating means 15, an ionizing particle generating means 15, An ionizing particle shielding unit 36 that shields the ionizing particles generated by the ionizing particle generation unit 15 by being installed between the gas and prevents the gas from being ionized, and a shield that drives the ionizing particle shielding unit 36 Means driving means 37, gas purifying means 17 for removing ions in the gas flowing into the measurement chamber 13, and gas for guiding the ionizing particles to narrow down a gas such as air that is ionized. Collected by the focusing means 20, the ion collecting means 21 for collecting ions transported together with the gas in the measurement chamber 13, the power supply means 23 for supplying power to the electrode 22 of the ion collecting means 21, and the ion collecting means 21. Current measuring means 24 for measuring ions as current, data processing means 25 for processing data of the measured current value, and gas transport means 26 for transporting the gas in the measurement chamber 13 to the ion collecting means 21 through the gas converging means 20. And gas purifying means 27 for purifying the gas after passing through the ion collecting means 21.

  Next, the operation (measurement method) of the radiation measurement apparatus 10F will be described.

In this radiation measurement apparatus 10F, neutrons emitted from the radiation source 12 of the measurement object 11 are decelerated by the measurement object 11 and surrounding objects to become thermal neutrons, and these thermal neutrons are ionized particle generating means 15 and atomic nuclei. A reaction occurs. When the ionizable particle generating means 15 is ¹⁰ B, ¹⁰ B (B-10) undergoes a (n, α) reaction with thermal neutrons to generate 7Li and α particles, and the ionizable particles are released.

  The generated ionizing particles ionize the gas in the measurement chamber 13 to generate ion pairs. At this time, the ionizing particle blocking means 37 is driven by the shielding means driving means 38, moves to the front surface of the ionizing particle generating means 15, and sets the ionizing particles in a shielded state. The gas inside the measurement chamber 13 is transported by the gas transporting means 26 in a state where the ionizing particles are shielded, and is guided to the ion collecting means 21 through the gas converging means 20.

  The ion collecting means 20 collects ions transferred together with the gas in the measurement chamber 13, and measures the current value of the collected ions as a gross current value by the current measuring means 24. The gross current value is calculated by subtracting the background current value measured in advance by the data processing means 25, and the neutron of the measurement object 11 is calculated using a conversion constant from the net current value to the neutron intensity. The strength can be determined.

  According to the radiation measurement apparatus 10F shown in the seventh embodiment, the measurement container 14 and the ionizing particle generation means 15 in which the measurement chamber 13 is formed can be enlarged according to the required neutron detection efficiency. On the other hand, the size of the ion collecting means 21 can be reduced without making it the same as the size of the measurement chamber 13, and can be set to a size that creates an appropriate electric field. Therefore, it is possible to obtain the radiation measurement apparatus 10F that can measure neutrons easily and efficiently with respect to the measurement object 11 that emits radiation other than neutrons.

In the description of the second to seventh embodiments of the radiation measuring apparatus according to the present invention, the ionizable particle generating means 15 is composed of ¹⁰ B (B-10), and ¹⁰ B is composed of neutrons (n, α) An example in which ionizing particles are generated by reaction is shown. Even if the ionizing particle generating means 15 is ⁶ Li which causes (n, t) reaction with neutrons, it reacts with (n, α) reactions with neutrons. Even if it is ⁶ Li that occurs, or an object that contains ³ LHe that causes (n, p) reaction with neutrons, ²³⁵ U, U isotopes, Pu isotopes that cause (n, f) reactions with neutrons. And at least one of these elements and their isotopes may be used.

  Further, in the radiation measuring apparatuses 10B to 10E shown in the third to sixth embodiments, thermal neutron absorption means (not shown) surrounding the neutron moderator and the measured current value of the epithermal neutrons. Data processing means 25 for calculating the intensity may be provided, and epithermal neutrons may be measured by the data processing means 25.

[Eighth Embodiment]
An eighth embodiment of the radiation measuring apparatus according to the present invention will be described.

  The radiation measuring apparatus 10G shown in the eighth embodiment is a radiation measuring apparatus provided with a neutron intensity measuring means and a radiation source separating means (both not shown) in the radiation measuring apparatus 10F shown in FIG. .

  The neutron intensity measuring means calculates the net current value by subtracting the background current value measured in the state where the ionizing particles are shielded from the gross current value measured in the state where the ionizing particles are not shielded, to obtain the neutron intensity. Is a means for obtaining the chamber strength of the measuring object 11. The radiation source separation means is means for classifying the radiation source of the measurement object 11 into uranium (U), plutonium (Pu), and TRU based on the neutron intensity of the measurement object 11 and the intensity other than neutrons.

Here, as a representative of U, Pu, TRU, when assuming the release rate of spontaneous fission neutrons per gram of ²⁴⁴ Cm, and oxides of U, Pu, TRU, (α , N) An example of the emission rate of neutrons generated by the reaction and an example of the α-ray emission rate are expressed by the following emission rate surface.

In the emission rate table, the abundance ratio of U is natural uranium, Pu is about 75 wt% for ²³⁹ Pu, and about 18 wt% for ²⁴⁰ Pu. In the emission rate table, the ratio of the emission rate of neutrons to α rays is expressed with U as a reference. The release rate ratio is 1.0 for U, 0.138 for Pu, and 7.95 for ²⁴⁴ Cm, and varies greatly depending on the target of U, Pu, and ²⁴⁴ Cm.

Therefore, by calculating the intensity ratio of neutron / α-ray from the neutron intensity and α-ray intensity, and comparing this intensity ratio with the neutron / α-ray intensity ratio of U, Pu, ²⁴⁴ Cm determined in advance, The target document can be easily obtained.

  The radiation measurement apparatus 10G shown in the eighth embodiment partially ionizes the gas in the measurement chamber 13 by shielding the ionizable particles generated by the ionizable particle generating means 15 in the measurement chamber 13 of the measurement container 14. The ionizing particle shielding means 37 for preventing the ionizing particles, the shielding means driving means 38 for driving the ionizing particle shielding means 37, and the background current value in the state where the ionizing particles are shielded, in the state where the ionizing particles are not shielded. A means for calculating a net current value by subtracting from the measured gross current value and a means for calculating a neutron intensity using a conversion constant from the net current value to a neutron intensity are configured, and the net current value calculating means A data processor 25 is composed of the neutron intensity calculating means.

  Further, the radiation measuring apparatus 10G calculates a net current value by subtracting a background current value measured in a state where the ionizing particles are shielded from a gross current value measured in a state where the ionizing particles are not shielded, and calculates a neutron intensity. Means for subtracting the current value of the measurement object measured in a state where the ionizing particles are shielded in the absence of the measurement object from the background current value, and obtaining the intensity other than neutrons, and the neutron intensity And means for classifying the radiation source of the measurement object into uranium, plutonium, and TRU based on the intensity other than neutrons.

  If two types of radiation source targets are known, the mixing rate can also be obtained from the measured emission rate ratio if the relationship between the mixing rate and the neutron / α-ray emission rate ratio is obtained in advance.

According to the radiation measuring apparatus 10G shown in the eighth embodiment, not only neutrons but also the source of the generation source (radiation source 12) that emits the neutrons can be distinguished from U, Pu, and ²⁴⁴ Cm. When there are two types of mixing, the mixing ratio can be obtained. It is possible to obtain a radiation measuring apparatus that can easily and efficiently measure neutrons.

[Ninth Embodiment]
FIG. 8 is a schematic configuration diagram showing a ninth embodiment of the radiation measuring apparatus according to the present invention.

  This radiation measuring apparatus 10H is a radiation measuring apparatus that accurately and efficiently measures radiation intensity from a measurement object 11 that emits not only neutrons but also α rays, β rays, and γ rays from a radiation source 12. is there.

  In the description of the radiation measurement apparatus 10H shown in FIG. 8, the same components as those of the radiation measurement apparatus 10 shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted or simplified.

  This radiation measuring apparatus 10H divides a measurement chamber 13 formed in a measurement container 14 into first to fourth measurement chambers 13a, 13b, 13c, and 13d, and stores a measurement object 11 in a first measurement chamber. 13a generates ionized ions by α rays, generates ionized ions by β rays in the second measurement chamber 13b surrounding the first measurement chamber 13a, and in the third measurement chamber 13c surrounding the second measurement chamber 13b. Ionized ions caused by neutron beams are generated, and ionized ions by γ rays are generated in the fourth measurement chamber 13d surrounding the third measurement chamber 13c. The first to fourth measurement chambers 13a to 13d are configured in a substantially concentric multilayer structure using the characteristics of radiation (α rays, β rays, neutron rays, γ rays) emitted from the radiation source 12. is there.

  The first to fourth measurement chambers 13a to 13d that partition the measurement chamber 13 in the measurement container 14 concentrically are provided with gas purification means 17 for purifying ions of the flowing gas. The gas purification means 17 (17a to 17d) is provided for each measurement chamber in order to remove gas ions flowing into the first to fourth measurement chambers 13a to 13d.

  The gas ions flowing into the measurement chambers 13a to 13d of the measurement chamber 13 are removed and purified by the first to fourth gas purification means 17a to 17d, while the gas flows out of the measurement chambers 13a to 13d. As a concentric first to fourth gas transport path 40a to 40d, and a transport path switching means 41 for switching each gas transport path 40a to 40d, and this transport path switching means 41 is provided. The ion collecting means 21 is connected via the path switching means 41.

  The radiation measurement apparatus 10H includes a measurement object 11 having a radiation source 12 installed in a measurement chamber 13 of a measurement container 14, for example, a first measurement chamber 13a, and a wall that partitions the third measurement chamber 13c. An ionizing particle generating means 15 is installed.

  A radiation measurement apparatus 10H shown in the fourth embodiment includes a measurement container 14 in which a multi-layer measurement chamber 13 is formed concentrically and a radiation source 12 installed in a first measurement chamber 13a in the measurement chamber 13. Ions of gas flowing into the object 11 and the ionizing particle generating means 15 installed on the wall partitioning the third measurement chamber 13c of the measurement chamber 13 and the first to fourth measurement chambers 13a to 13d of the measurement chamber 13, respectively. The first to fourth gas purification means 17 (17a to 17d) for removing the gas and the first to fourth gas transport paths 40a to 40d from the first to fourth measurement chambers 13a to 13d in the measurement chamber 13 Route switching means 41 that guides through the gas, and ion collection that is guided by narrowing down the gas from the first to fourth gas transport routes 40a to 40d selectively switched by the transport route switching means 41. Means 21; power supply means 23 for supplying power to an electrode 22 for collecting ions guided to the ion collecting means 21 together with gas; current measuring means 24 for measuring ions collected by the ion collecting means 21 as current; Data processing means 25 for processing the data of the current value, gas transport means 26 for transporting the gas in the measurement chamber 13 to the ion collection means 21, and gas purification means 27 for purifying the gas after passing through the ion collection means 21 Consists of

  In addition, although the example which provided the gas purification means 27 in the downstream of the gas transport means 26 was shown, the gas after passing the gas purification means 26 is circulated to each measurement chamber 13a-13d of the measurement chamber 13 or the measurement chamber 13. A gas transport path (not shown) is provided, and ions in the gas are removed during the gas transport path or before flowing into the measurement chamber 13. A gas circulation means may be configured by providing a gas transport means.

  Incidentally, the radiation measuring apparatus 10H shown in FIG. 8 emits α rays, β rays, γ rays, and neutron rays from the radiation source 12 of the measurement object 11. In the first measurement chamber 13a of the measurement chamber 13, α-rays, in the second measurement chamber 13b β-rays, in the third measurement chamber 13c ionized particles resulting from the (n, α) reaction of neutrons, the fourth In the measurement chamber 13d, each radioactivity is obtained from the number of ions ionized by the influence of γ rays. Here, the material and thickness of the wall of the second measurement chamber 13b are selected so as to shield β rays and transmit γ rays.

  If the measurement chambers 13a to 13d in the measurement chamber 13 of the measurement container 14 are set as described above, the fourth measurement chamber 13d has only γ-rays, the third measurement chamber 13c has neutrons and γ-rays, and the second The measurement chamber 13b is β rays and γ rays, and the first measurement chamber 13a is α rays, β rays, and γ rays.

  In the radiation measuring apparatus 10H shown in the ninth embodiment, first, the fourth gas transport path 40d is selected by the transport path switching means 41. The gas in the fourth measurement chamber 13d is transported to the ion collecting means 21 via the gas transport path 40d and the transport path switching means 41, and the ion collecting means 21 is similar to that shown in the first embodiment. The ions contained in the gas in the fourth measurement chamber 13d are collected, and the current obtained by collecting the ions is measured by the current measuring means 24 as the gross current value.

  Thereafter, the third to first gases 41c to 41a are sequentially selected by the transport path switching means 41, and the gases in the third to first measurement chambers 13c to 13a are transported to the ion collecting means 21 to be used in the first embodiment. In the same manner as in the above, ions in the gases in the measurement chambers 13c to 13a are collected by the ion collecting means 21, and ions in the gases in the third to first measurement chambers 13c to 13a are collected in the ion collecting means 21. And the gross current value due to ions contained in the gas in the third to first measurement chambers 13c to 13a is measured.

  Next, the background current values of the measurement chambers 13a to 13d when the measurement object 11 is not present in the first measurement chamber 13a in the measurement chamber 13 are measured by the current measurement unit 24 via the ion collection unit 21, Subsequently, the data processing means 25 performs data processing for subtracting the background current value from the gross current value to obtain the net current value. The net current values of the first to fourth measurement chambers 13a to 13d can be obtained from this data processing, respectively.

  The current value of the fourth gas transport path 13d is mainly caused by γ rays, the third measurement chamber 13c is neutron, the second measurement chamber 13b is β rays, and the first measurement chamber 13a is mainly α rays. Using these net current values obtained by measurement and the respective conversion constants obtained in advance, the intensity of α-rays, β-rays, neutron rays, and γ-rays of the measurement object 11 is obtained. Can do.

  In this case, γ rays are also mixed into the currents of the third and second measurement chambers 13c and 13b, and β rays and γ rays are also mixed into the current of the first measurement chamber 13a. Therefore, the currents in the third and second measurement chambers 13c and 13b correct γ-rays mixed based on the net current value in the fourth measurement chamber 13d, and the net current value in the first measurement chamber 13a is the fourth value. If the net current value in the measurement chamber 13d and the net current value in the second measurement chamber 1b in which the γ-rays are corrected are corrected, the intensity of radiation can be obtained with higher accuracy.

  In this radiation measurement apparatus 10H, the first measurement chamber 13a in the measurement chamber 13 can be enlarged according to the required radiation detection efficiency. On the other hand, the dimensions of the ion collecting means 21 are also the same as those of the measurement chamber 13. The size can be reduced without making it the same as the size, and the size can be set so as to create an appropriate electric field. Further, neutrons can be obtained by correcting the influence of γ rays, and α rays, β rays and γ rays can be easily obtained by using the same radiation measurement system (ion collection means 21, current measurement means 24 and data processing means 25). Can be requested.

  Therefore, it is possible to obtain a radiation measuring apparatus that can measure radiation (α rays, β rays, γ rays, and neutron rays) easily and with high efficiency.

The block diagram which shows 1st Embodiment of the radiation measuring device which concerns on this invention. The block diagram which shows 2nd Embodiment of the radiation measuring device which concerns on this invention. The block diagram which shows 3rd Embodiment of the radiation measuring device which concerns on this invention. The block diagram which shows 4th Embodiment of the radiation measuring device which concerns on this invention. The block diagram which shows 5th Embodiment of the radiation measuring device which concerns on this invention. The block diagram which shows 6th Embodiment of the radiation measuring device which concerns on this invention. The block diagram which shows 7th and 8th embodiment of the radiation measuring device which concerns on this invention. The block diagram which shows 9th Embodiment of the radiation measuring device which concerns on this invention. The figure explaining an example of the conventional neutron detector. The block diagram which shows the conventional radiation measuring device.

Explanation of symbols

10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H Radiation measurement apparatus 11 Measurement object 12 Radiation source 13 Measurement chamber (measurement room)
14 Measuring container (main casing)
15 ionizing particle generating means 16 support means 17 gas purifying means 18 installation stand (stand)
20 gas converging means 21 ion collecting means 22 electrode 23 power supply means 24 current measuring means 25 data processing means 26 gas transport means 27 gas purifying means 28 cylinder 29 core wire (electrode)
30 Gas transport path 33 Neutron moderator (thermal neutron generation means)
34 Cover (Antistatic means)
35 Neutron absorber 36 Ionizing particle shielding means 37 Shielding means driving means 40a, 40b, 40c, 40d Gas transport path 41 Transport path switching means

Claims (13)

A measurement container having a measurement chamber in which a measurement object is placed;
An ionizable particle generating means installed in the measurement chamber and generating ionizable particles by reacting with neutrons;
A support means to which the ionizing particle generating means is attached;
Gas purification means for removing ions in the gas flowing into the measurement chamber;
Ion collecting means for guiding ions generated by ionizing the generated ionizing particles together with the gas in the measurement chamber;
Power supply means for supplying power to the electrodes of the ion collection means;
Current measuring means for measuring ions collected by the ion collecting means as current;
Data processing means for processing the measured current value and measuring neutrons from a conversion constant of neutron intensity;
A radiation measuring apparatus comprising gas transporting means for transporting the gas in the measurement chamber to the ion collecting means. The measurement object according to claim 1, further comprising a gas purification means for purifying a gas after passing through the ion collection means, while a measurement object having a radiation source is installed in the measurement chamber of the measurement container or in the vicinity of the outside of the measurement chamber. Radiation measurement device. A neutron moderator that decelerates neutrons emitted from the object to be measured, and an antistatic unit such as a cover that covers the periphery in order to prevent the neutron moderator from being charged, are provided in the measurement chamber of the measurement container. The radiation measuring apparatus according to claim 1 or 2 provided in. The measurement object is installed near the outside of the measurement container, and ionization particle generating means for generating ionizable particles by reacting with neutrons in the measurement chamber of the measurement container and neutrons emitted from the measurement object The radiation measuring apparatus according to claim 1, further comprising a neutron moderator for decelerating. The radiation measurement apparatus according to claim 1, further comprising a neutron moderating unit that is disposed around the measurement container and decelerates neutrons emitted from the measurement object. 7. The thermal neutron recovery means surrounding the neutron moderating means and a data processing means for calculating the intensity of epithermal neutrons from the current value measured by the current measurement means. Radiation measurement device. The neutron moderation means that is disposed around the measurement container and decelerates neutrons emitted from the measurement object, and a measurement object having a radiation source is installed outside the neutron moderation means. Radiation measurement equipment. The ionizing particle generating means includes ⁶ Li causing (n, t) reaction with neutron, ⁶ Li or ¹⁰ B causing (n, α) reaction with neutron, and (n, p) reaction with ³ neutron. The radiation according to claim 1, wherein an object containing He and at least one of ²³⁵ U, U isotopes, Pu isotopes and Th isotopes that cause (n, f) reaction with the neutrons are selected. measuring device. Ionizing particle shielding means for preventing ionization of gas by shielding the ionizing particles generated by the ionizing particle generating means in the measurement chamber of the measurement container;
The radiation measuring apparatus according to claim 1, further comprising shielding driving means for driving the ionizing particle shielding means. The net current value is calculated by subtracting the background current value measured for ionizing particles in the state shielded by the ionizing particle shielding means from the gross current value measured in the absence of ionizing particle shielding, and the neutron intensity Means for obtaining the neutron intensity from the conversion constant of
Means for subtracting the current value measured in a state where there is no measurement object and ionizing particles are shielded from the background current value to obtain intensity other than neutrons;
The radiation measuring apparatus according to claim 9, further comprising means for classifying a radiation area of the measurement object into U, Pu, and TRU based on the neutron intensity and the intensity other than the neutron. In the measurement chamber of the measurement container, a first measurement chamber that encloses the measurement object and generates ionized ions by α rays, a second measurement chamber that encloses this measurement amount and generates ionized ions by β rays, A third measurement chamber that surrounds the measurement chamber and generates ionized ions caused by neutron rays, and a fourth measurement chamber that surrounds the third measurement chamber and generates ionized ions by γ rays,
Ionizing particle generating means installed in the third measurement chamber;
First to fourth gas transport paths for transporting gases in the first to fourth measurement chambers of the measurement chamber;
Ion collection means for collecting ions in the gas transported through each gas transport path;
Power supply means for supplying power to the electrodes of the ion collection means;
Current measuring means for measuring ions collected by the ion collecting means as current; and
Data processing means for performing data processing of the measured current value;
Gas transport means for transporting the gas in each measurement chamber of the measurement chamber to the ion collection means,
The radiation measurement apparatus characterized in that the data processing means measures the intensity of α rays, β rays, γ rays and neutron rays from the current value of ions contained in the gas in each measurement chamber of the gas chamber. A gas transport path for circulating the gas after passing through the gas transport means to a measurement chamber in a measurement container;
The radiation measurement apparatus according to claim 1, further comprising a gas purification unit that removes ions in the gas before the circulated gas flows into the measurement chamber. Ionizable particles are generated by at least one of the (n, α) reaction, (n, p) reaction, and (n, f) reaction between the neutrons emitted from the measurement object and the ionizing particle generating means. And
The generated ionizing particles ionize the gas in the measurement chamber to generate ion pairs,
The generated ion pair is transported to the ion collecting means, and the collected ions are measured as current or electric quantity,
A radiation measurement method comprising measuring the intensity of radiation from the current value using a conversion constant.

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