Measurement system, measurement method, and program

Abstract

This technology provides a way to measure the moisture content and water content of fuel debris storage containers. [Solution] The measurement system comprises a neutron generator that irradiates the object to be measured with neutrons, a neutron detector that detects neutrons in different energy bands, and a measuring device that generates a neutron spectrum based on the neutron count rate detected by the neutron detector and measures the amount of water and / or hydrogen in the object to be measured based on the spectral information of the medium velocity group and above in the neutron spectrum.

Description

Technical Field

[0001] The present disclosure relates to a measurement system, a measurement method, and a program for measuring the residual moisture content, water content, and amount of hydrogen in a storage container for fuel debris.

Background Art

[0005] A method is needed to measure the moisture content of fuel debris storage containers.

[0006] This disclosure provides a measurement system, measurement method, and program that can solve the above-mentioned problems. [Means for solving the problem]

[0007] The measurement system disclosed herein comprises a neutron generator that irradiates an object to be measured with neutrons, a neutron detector that detects neutrons in different energy bands, and a measuring device that generates a neutron spectrum based on the neutron count rate detected by the neutron detector and measures the amount of water and / or hydrogen in the object to be measured based on spectral information of the medium velocity group and above from the neutron spectrum.

[0008] The measurement method of the present disclosure involves detecting the neutron count rate of an object to be measured using a neutron detector that detects neutrons in different energy bands, generating a neutron spectrum based on the detected neutron count rate using a computer, and measuring the amount of water and / or hydrogen in the object to be measured based on spectral information of the medium-velocity group and above from the neutron spectrum.

[0009] The program of this disclosure causes a computer to generate a neutron spectrum based on the neutron count rate of an object to be measured detected by a neutron detector that detects neutrons in different energy bands, and to perform a process of measuring the amount of water and / or hydrogen in the object to be measured based on spectral information of the medium-velocity group and above from the neutron spectrum. [Effects of the Invention]

[0010] According to the measurement system, measurement method, and program of this disclosure, the moisture content of a fuel debris storage container can be measured. [Brief explanation of the drawing]

[0011] [Figure 1] This is a first schematic diagram showing an example of a measurement system according to the embodiment. [Figure 2] This is a second schematic diagram showing an example of a measurement system according to the embodiment. [Figure 3] This is a block diagram showing an example of a measuring device according to an embodiment. [Figure 4] This figure shows an example of a neutron spectrum according to the embodiment. [Figure 5] This is a flowchart showing an example of the moisture content estimation process according to the embodiment. [Figure 6] This is a flowchart showing an example of the material property information estimation process according to the embodiment. [Figure 7] This figure shows an example of the hardware configuration of the measuring device in the embodiment. [Modes for carrying out the invention]

[0012] The measurement system described herein will be explained below with reference to the drawings. (composition) Figure 1 shows an example of a measurement system 100 for measuring the amount of water and moisture content in a container that stores fuel debris. The measurement system 100 comprises a pair of neutron generators 1 and neutron detectors 2, a container 4 containing fuel debris, a transport device 3 capable of transporting the container 4 in the direction of the arrow (x-axis direction), and a measurement device 10 for measuring the amount of water in the container 4. The neutron generator 1 irradiates the neutron detector 2 with neutrons. The neutron detector 2 detects neutrons irradiated from the neutron generator 1 while the container 4 is sandwiched between them. The neutron detector 2 also detects neutrons caused by spontaneous fission emitted from the container 4 when the neutron generator 1 is not irradiating it with neutrons. The measurement device 10 is connected to the neutron detector 2 and acquires the neutron count rate detected by the neutron detector 2. With the container 4 in between, the neutron generator 1 can irradiate the entire container 4 with neutrons, and the neutron detector 2 can detect all the neutrons in the container 4. The measuring device 10 generates a neutron spectrum from the acquired neutron count rate and measures the water content of the container 4 based on the neutron spectrum. The following explanation will use the case of measuring the water content inside the container 4 as an example. For water content, the weight of the contents stored inside the container 4 is obtained using the weighing scale 8 (Figure 2), and the water content of the container 4 can be measured by dividing the measured water content inside the container 4 by that weight. In addition to the water content and water content inside the container 4, the measuring device 10 can also estimate the number of hydrogen atoms and molecules inside the container 4.

[0013] The neutron detector 2 detects neutrons in a relatively low energy range. In this embodiment, in order to generate a neutron spectrum spanning a wide energy range, measures are taken to change the energy range of neutrons that the neutron detector 2 can detect by installing a moderator (such as polyethylene) 5 around the neutron detector 2 or by installing a neutron-absorbing material (such as Cd) not shown. For example, increasing the thickness of the moderator 5 increases the degree of thermalization of neutrons passing through the moderator 5, making them slower. In other words, the thicker the moderator 5, the higher the energy range of neutrons that can be detected by the neutron detector 2. For example, in Figure 1, a measurement environment is created in which no moderator 5 is installed around the neutron detector 2, and multiple measurement environments are created in which moderators 5 of different thicknesses are installed around the neutron detector 2, and the neutron count rate is measured for each measurement environment. Then, the count rates for each energy obtained from these measurements are converted back into the original neutron count rates for each energy before passing through the moderator 5, and a neutron spectrum is generated.

[0014] To detect neutron count rates in different energy bands, as shown in Figure 1, moderators of varying thicknesses may be switched and installed around a single neutron detector 2, or, as illustrated in Figure 2, neutron detectors 2 may be prepared for each moderator thickness and arranged side by side. Alternatively, a neutron absorber may be installed around the neutron detector 2 in place of / in addition to the moderator 5. Installing a neutron absorber has the effect of absorbing neutrons in the lower energy band, thereby cutting out a certain amount of neutrons in that energy band that can be detected by the neutron detector 2. For example, by installing the neutron absorber in front of the moderator (farther from the neutron detector 2), the lower energy band can be reduced, and then neutrons in the medium-to-high energy band can be passed through the moderator 5, allowing for measurements that exclude the influence of the lower energy band, and thus improving detection accuracy. Furthermore, in addition to the neutron detector 2, a fast neutron detector 2d (Figure 2) for detecting fast neutrons may be installed, and neutrons in the high-energy band may be detected by the fast neutron detector 2d without installing a thick moderator 5. In this embodiment, these neutron detectors 2, moderators 5 of multiple thicknesses, neutron absorbers, and fast neutron detectors can be arbitrarily combined for the purpose of generating a neutron spectrum, and there are no particular limitations on the configuration of neutron detectors for detecting neutrons in different energy bands. Also, the neutron generator 1 may use multiple neutron generators, each irradiating with different energies.

[0015] Furthermore, in order to measure the moisture content and water content of container 4, as well as the physical properties of the fuel debris contained in container 4, the measurement system 100 may be equipped with an X-ray CT (Computed Tomography), a gamma-ray detector, etc. Figure 2 shows another example configuration 100a of the measurement system. Figure 2 is a top view of the measurement system 100a. The measurement system 100a comprises a neutron generator 1a and a neutron detector 2a (a bare neutron detector 2 without a moderator 5, etc.), a neutron generator 1b, a neutron detector 2b, and a thick moderator 5b installed around the neutron detector 2b, a neutron generator 1c, a neutron detector 2c, and a thin moderator 5c installed around the neutron detector 2c, a neutron generator 1d and a fast neutron detector 2d, a gamma-ray generator 6 (Co-60, etc.) and a gamma-ray detector 7, a weighing scale 8, an X-ray CT device 9, a transport device 3, and a measurement device 10. In Figure 2, two moderators of different thicknesses are provided, but the number of neutron detectors 2 equipped with moderators 5 of different thicknesses may be three or more, or it may be just one. Although not shown in the diagram, a neutron detector 2 equipped with a neutron absorber may be installed in place of the moderator 5, or a neutron absorber may be installed around the neutron detectors 2b and 2c in addition to the moderators 5b and 5c. Neutron detectors 2a to 2d are used to detect neutrons in various energy bands and obtain a neutron spectrum. The neutron transmittance of container 4 may also be measured using the neutron generator 1a and neutron detector 2a, and the material composition inside container 4 may be estimated from the measured neutron transmittance. The gamma-ray generator 6 and gamma-ray detector 7 can be used to measure the gamma-ray characteristics of container 4 (e.g., gamma-ray transmittance and gamma-ray counting rate) and to estimate the material inside container 4 from the measured gamma-ray characteristics. The weighing scale 8 can be used to measure the weight of container 4, subtract the weight of container 4 itself to obtain the weight of the contents inside container 4, and then measure the water content of container 4 by (water content inside container 4 ÷ weight of contents inside container 4). The X-ray CT scanner 9 can be used to acquire density information of the object stored in the container 4 and to estimate the substance inside the container 4 from the acquired density information.In the case of the measurement system 100a in FIG. 2, while transporting the container 4, measurements are taken of the weight, neutron count rate in each energy band, neutron transmittance, gamma-ray peak, gamma-ray transmittance, and the like. The measuring device 10 is connected to neutron detectors 2a to 2e, a gamma-ray detector 7, and a weighing scale 8. The measuring device 10 generates a neutron spectrum from the neutron count rates detected by the neutron detectors 2a to 2e, and measures the moisture content of the container 4 based on the neutron spectrum. Further, the measuring device 10 estimates the physical properties information of the container 4, such as the neutron transmittance, gamma-ray characteristics, and density information of the container 4.

[0016] FIG. 3 shows an example of the functional configuration of the measuring device 10. FIG. 3 includes an acquisition unit 11, a moisture content estimation unit 12, a physical property estimation unit 13, and a storage unit 14. The acquisition unit 11 acquires the measurement values measured by the neutron detectors 2, 2a to 2e, the gamma-ray detector 7, the weighing scale 8, and the X-ray CT device 9. The moisture content estimation unit generates a neutron spectrum based on the neutron count rates measured by the neutron detectors 2, 2a to 2e, focuses on the energy band above the intermediate speed group of the generated neutron spectrum, and estimates the moisture content based on the correlation data between the neutron spectrum above the intermediate speed group and the moisture content. Further, the moisture content estimation unit divides the estimated moisture content by the weight of the contents stored in the container 4 to estimate the moisture content rate of the container 4. Further, the moisture content estimation unit estimates the number of hydrogen atoms or the number of hydrogen molecules (number of hydrogen molecules = number of hydrogen atoms × 2) corresponding to the estimated moisture content. Since there is the following relationship between the number of hydrogen atoms and the amount of substance of water molecules (moisture content), the moisture content estimation unit calculates the number of hydrogen atoms and the like using the following formula. Number of hydrogen atoms = amount of substance of water molecules × Avogadro's number × 2 Note that the object that can be estimated by the neutron spectrum is precisely the number of hydrogen atoms. Since neutrons cause physical behavior (scattering and absorption reactions) depending on the atomic number density of substances in the medium and the reaction cross-section of each substance, the change in the neutron spectrum depends on the abundance of atoms. In the case of the container 4 containing fuel debris, the neutron spectrum changes depending on the abundance of hydrogen atoms. In the present embodiment, the change in the neutron spectrum depending on the number of hydrogen atoms is utilized to estimate the moisture content in the container 4 based on the neutron spectrum.

[0017] The physical property estimation unit 13 estimates the physical properties of the container 4 from the neutron transmittance, gamma-ray characteristics, and density information of the container 4. The memory unit 14 stores correlation data between neutron spectra of medium velocity and above and water content, a physical properties database containing physical property information such as neutron transmittance, gamma-ray transmittance, gamma-ray peak, and density information for each material, and measurement values ​​acquired by the acquisition unit 11.

[0018] Figure 4 shows an example of a neutron spectrum based on the neutron count rate measured by neutron detector 2. The vertical axis in Figure 4 represents the neutron flux (n / cm²). 2 / s), and the horizontal axis is energy (MeV). Graphs 41 to 44 are neutron spectra measured with the measurement system 100 illustrated in FIG. 1 with an object having a known moisture content placed in the container 4. Graph 41 is the neutron spectrum of the measurement object sample with a moisture content = X1 (g or kg) containing relatively a lot of water, Graph 42 is the neutron spectrum of the measurement object sample with a moisture content of X2 (g or kg), Graph 43 is the neutron spectrum of the measurement object sample with a moisture content of X3 (g or kg), and Graph 44 is the neutron spectrum of the measurement object with a moisture content of 0 (g or kg). The relationship of the moisture content is X1>X2>X3. Here, if the region where the neutron energy is 0.5 eV or less is called the slow group, the region of 0.5 eV to 0.1 MeV is called the medium speed group, and the region of 0.1 MeV or more is called the fast group, the inventor has found that the magnitude of the water content appears in the waveform of the medium speed group or higher (especially the medium speed group) of the neutron spectrum. Specifically, as shown in FIG. 4, it has been found that the higher the moisture content, the more the neutron spectrum of the medium speed group becomes a waveform with a gentle slope or a waveform close to horizontal instead of a sharply rising waveform on the right shoulder. Therefore, measurement objects with various moisture contents are prepared, and in a measurement environment devised so as to obtain neutron count rates in different energy bands as described in FIGS. 1 and 2, the neutron spectra of those measurement objects are obtained and registered as "correlation data between neutron spectrum and moisture content". Then, the neutron spectrum of the container 4 to be evaluated is compared with the "correlation data between neutron spectrum and moisture content", and the neutron spectrum with the waveform of the neutron spectrum of the medium speed group being the closest is obtained from the "correlation data", and the moisture content corresponding to the obtained neutron spectrum is estimated as the moisture content of the container 4. Note that the "correlation data between neutron spectrum and moisture content" may be created from two types of correlation data between neutron spectrum and moisture content when measuring neutrons generated from the neutron generator 1 and transmitted through the measurement object, and correlation data between neutron spectrum and moisture content when measuring neutrons emitted from the measurement object in a state where the neutron generator 1 does not generate neutrons, and registered in the storage unit 14.

[0019] Here, with reference to Figures 1 and 4, the method for generating the neutron spectrum of container 4 will be explained. First, with nothing placed around the neutron detector 2, neutrons are generated from the neutron generator 1 and detected by the bare neutron detector 2 after passing through container 4. In the measuring device 10, the acquisition unit 11 acquires the detected neutron count rate and records the value in the storage unit 14. Also, with no neutrons generated from the neutron generator 1, neutrons emitted from container 4 are detected by the bare neutron detector 2 and the detected neutron count rate is recorded in the storage unit 14. The recorded neutron count rates for each energy are converted into a neutron spectrum by known methods, such as converting them into neutron flux. This yields a neutron spectrum of the low-energy group (for example, the range of 401 in Figure 4). Neutrons emitted from neutron generator 1 and transmitted through container 4, as well as neutrons generated from container 4 itself (spontaneous fission neutrons), are measured individually and converted into neutron spectra. The amount of water is then estimated individually by comparing each neutron spectrum with "correlation data between neutron spectra and water content" collected in the corresponding measurement environment. This improves the accuracy of the estimation.

[0020] Next, with the thinnest moderator 5 placed around the neutron detector 2, neutrons are generated from the neutron generator 1, and the neutron count rate detected by the neutron detector 2 is recorded in the storage unit 14. Also, with the thinnest moderator 5 placed around the neutron detector 2, and without generating neutrons from the neutron generator 1, the count rate detected by the neutron detector 2 from neutrons emitted from the container 4 is recorded in the storage unit 14. Each of the recorded neutron count rates is converted into a neutron spectrum using a known method. This yields a neutron spectrum in the range of, for example, 402, as shown in Figure 4. Next, with the second thinnest moderator 5 placed around the neutron detector 2, the neutron count rates detected with and without generating neutrons from the neutron generator 1 are recorded in the storage unit 14 and converted into a neutron spectrum. This yields a neutron spectrum in the range of, for example, 403, as shown in Figure 4. Similarly, the thickness of the moderator is changed to measure the neutron count rate in other energy bands and convert it into a neutron spectrum. For example, range 405 in Figure 4 is the neutron spectrum based on the neutron count rate measured with the thickest moderator 5 installed (or the neutron count rate measured by the fast neutron detector 2d), and range 404 is the neutron spectrum based on the neutron count rate measured with the second thickest moderator 5 installed. Then, the neutron spectra of each energy band are integrated with respect to energy to generate a wide range of neutron spectra as illustrated in Figure 4. The relationship between the thickness of the moderator and the energy bands of neutrons detectable by the neutron detector 2 is analyzed in advance, and moderators of each thickness are prepared so that a neutron spectrum of the entire range can be obtained (at least so that the neutron spectrum of the medium-velocity group used for estimating the amount of water can be obtained). Furthermore, the relationship between ranges 401 to 405 shown in Figure 4 and the thickness of the moderator described above is for convenience only and is not limited to this. Note that graph 42a in Figure 4 shows the spectrum when a neutron-absorbing material is placed around the neutron detector 2. By placing the neutron-absorbing material, the neutron count rate in the low-energy band detected decreases.

[0021] (operation) Next, we will explain the process for estimating the moisture content of container 4 using Figure 5. Figure 5 is a flowchart showing an example of the moisture content estimation process according to the embodiment. First, the acquisition unit 11 acquires the neutron count rate measured for different energy bands (step S1). For example, the acquisition unit 11 acquires the neutron count rate detected by the bare neutron detector 2 with the container 4 sandwiched between the neutron generator 1 and the neutron detector 2, and the neutron count rate in each measurement environment detected by installing moderators 5 of different thicknesses (two types each for when neutrons are generated from the neutron generator 1 and when they are not), and records this data in the storage unit 14.

[0022] Next, the moisture content estimation unit 12 reads the neutron count rate from the memory unit 14 according to the thickness of the moderator and corrects the energy level using a response function (step S2). The response function is a function configured to output the energy of the neutrons before they pass through the moderator 5 when the energy associated with the thickness of the moderator 5 and the detected neutron count rate is input. For the neutrons detected by the neutron detector 2 (for example, range 402 in Figure 4), the moisture content estimation unit 12 inputs the energy of each neutron and the thickness of the moderator 5 used for measurement in range 402 into the response function and corrects it to the original energy before it passed through the moderator 5. The moisture content estimation unit 12 records the corrected energy and neutron count rate in the memory unit 14. For other ranges 403 to 405, etc., the moisture content estimation unit 12 also corrects the energy level of the neutrons detected in the measurement environment according to the thickness of the moderator 5 installed when measuring the neutron count rate.

[0023] Next, the moisture content estimation unit 12 generates a neutron spectrum (step S3). The moisture content estimation unit 12 organizes the neutron count rate obtained in step S2, after energy level correction, in terms of neutron energy, and generates a neutron spectrum.

[0024] Next, the moisture content estimation unit 12 extracts the medium velocity group from the neutron spectrum (step S4). For example, the moisture content estimation unit 12 extracts the range of 0.5 eV to 0.1 MeV from the neutron spectrum generated in step S3. Next, the moisture content estimation unit 12 estimates the moisture content of container 4 using the "correlation data between neutron spectra and moisture content" (hereinafter referred to as "correlation data") of the medium velocity group (step S5). The moisture content estimation unit 12 refers to the "correlation data" when neutrons are generated from the neutron generator 1 and determines which moisture content neutron spectrum waveform in the "correlation data" matches or approximates the waveform of the medium velocity group neutron spectrum measured with neutrons generated from the neutron generator 1. Similarly, the moisture content estimation unit 12 refers to the "correlation data" for cases where neutrons are not generated from the neutron generator 1 and determines which neutron spectrum waveform of the medium velocity group measured without neutron generation from the neutron generator 1 matches or approximates the waveform of the neutron spectrum of which moisture content included in the "correlation data". For example, if in both cases the waveform of water matches or approximates that of X1 (g or kg), the moisture content estimation unit 12 estimates the moisture content of container 4 to be X1 (g or kg). If the neutron spectrum matches or approximates that of different moisture content when neutrons are generated from the neutron generator 1 and when neutrons are not generated from the neutron generator 1, the moisture content estimation unit 12 may calculate the average or weighted average of each moisture content and estimate the moisture content of container 4 to be the calculated average or weighted average. The moisture content estimation unit 12 outputs the estimated moisture content to a display device or electronic file (not shown). Alternatively, the moisture content estimation unit 12 may calculate the moisture content of container 4 by dividing the estimated moisture content by the weight of the contents of container 4 and output the moisture content to a display device or the like. Or, the moisture content estimation unit 12 may output the number of hydrogen atoms or molecules in container 4 to a display device or the like.

[0025] In the above explanation, step S4 involves extracting the medium-velocity group of neutron spectra generated in step S3. However, it is also possible to extract the medium-velocity group or higher and estimate the water content by comparing it with the "correlation data between neutron spectra and water content" of the medium-velocity group or higher in step S5.

[0026] Figure 6 is a flowchart showing an example of the material property information estimation process according to the embodiment. The physical property estimation unit 13 acquires the neutron transmittance (step S11). For example, the physical property estimation unit 13 acquires the neutron count rate A detected by the bare neutron detector 2 when neutrons are generated from the neutron generator 1 with the container 4 sandwiched between the neutron generator 1 and the neutron detector 2, and the neutron count rate B detected by the bare neutron detector 2 when neutrons are generated from the neutron generator 1 with nothing between the neutron generator 1 and the neutron detector 2, from the acquisition unit 11. The unit then acquires the neutron transmittance by dividing the neutron count rate A by the neutron count rate B, and records this value in the storage unit 14.

[0027] Next, the physical property estimation unit 13 acquires the gamma-ray transmittance (step S12). For example, the physical property estimation unit 13 acquires the gamma-ray count rate A detected by the gamma-ray detector 7 when gamma rays are generated from the gamma-ray generator 6 with the container 4 sandwiched between the gamma-ray generator 6 and the gamma-ray detector 7, and the gamma-ray count rate B detected by the gamma-ray detector 7 when gamma rays are generated from the gamma-ray generator 6 with nothing between the gamma-ray generator 6 and the gamma-ray detector 7, from the acquisition unit 11. The gamma-ray transmittance is then calculated by dividing the gamma-ray count rate A by the gamma-ray count rate B, and this value is recorded in the storage unit 14.

[0028] Next, the physical property estimation unit 13 acquires the gamma-ray count rate (step S13). For example, the physical property estimation unit 13 places the container 4 between the gamma-ray generator 6 and the gamma-ray detector 7, and without generating gamma rays from the gamma-ray generator 6, acquires the gamma-ray count rate detected by the gamma-ray detector 7 from the acquisition unit 11 and records the value in the storage unit 14.

[0029] Next, the physical property estimation unit 13 acquires the count rate ratio of gamma rays with different energies (step S14). For example, the physical property estimation unit 13 places the container 4 between the gamma-ray generator 6 and the gamma-ray detector 7, generates gamma rays from the gamma-ray generator 6, acquires the gamma-ray count rate detected by the gamma-ray detector 7 from the acquisition unit 11, identifies the peaks of gamma-ray count rates in different energy bands from the acquired count rates, calculates the ratio of the count rates of the identified peaks, and records that value in the storage unit 14.

[0030] Next, the physical property estimation unit 13 acquires density information of the container 4 (step S15). For example, the physical property estimation unit 13 acquires the CT value measured by the X-ray CT device 9, converts the acquired CT value into density using a correspondence table between CT value and density, and records the calculated density in the storage unit 14.

[0031] Next, the physical property estimation unit 13 estimates the substance in the container 4 (step S16). The physical property estimation unit 13 estimates the substance in the container 4 based on the physical property information acquired in steps S11 to S15 and the physical property database. The physical property database registers physical property information for various substances, such as neutron transmittance, gamma-ray transmittance, gamma-ray count rate, the ratio of count rates of gamma rays with different energies, and density. The physical property estimation unit 13 refers to the physical property database and extracts substances for which approximate values ​​are registered for each piece of information acquired in steps S11 to S15, and outputs the extracted substances along with each piece of physical property information acquired in steps S11 to S15 to a display device or the like. Note that the physical property estimation unit 13 does not need to estimate all of the physical property information from steps S11 to S15, and may be configured to estimate only a part of it.

[0032] (effect) As described above, according to this embodiment, a neutron spectrum is generated by a neutron detector configured to acquire neutron count rates in different energy bands, and the amount of water is estimated by focusing on the waveform of the medium-velocity group in the neutron spectrum. This makes it possible to estimate the amount of water, water content, and amount of hydrogen (number of H atoms or molecules) in the container 4 containing fuel debris that contains a mixture of various materials. Furthermore, according to this embodiment, physical property information such as the neutron transmittance and gamma-ray transmittance of the container 4 is estimated by the neutron detector, gamma-ray detector, etc. From the physical property information, it is possible to estimate the various materials mixed in the container 4.

[0033] Figure 7 shows an example of the hardware configuration of the measuring device. The computer 900 includes a CPU 901, main memory 902, auxiliary memory 903, input / output interface 904, and communication interface 905. The measuring device 10 described above is implemented in the computer 900. The functions described above are stored in the auxiliary memory 903 in the form of programs. The CPU 901 reads the program from the auxiliary memory 903, expands it into the main memory 902, and executes the above processing according to the program. The CPU 901 also allocates a memory area in the main memory 902 according to the program. The CPU 901 also allocates a memory area in the auxiliary memory 903 to store the data being processed according to the program.

[0034] Furthermore, a program to implement all or part of the functions of the measuring device 10 may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be loaded into a computer system and executed to perform processing by each functional unit. Here, "computer system" includes hardware such as the OS and peripheral devices. Also, if a WWW system is used, "computer system" also includes the homepage provisioning environment (or display environment). Furthermore, "computer-readable recording medium" refers to portable media such as CDs, DVDs, USBs, and storage devices such as hard disks built into the computer system. In addition, if this program is distributed to computer 900 via a communication line, computer 900 that receives the program may load it into main memory 902 and execute the above processing. Furthermore, the above program may be for implementing part of the functions described above, and may also be able to implement the above functions in combination with programs already recorded in the computer system.

[0035] As described above, several embodiments relating to this disclosure have been explained, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be carried out in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0036] <Note> The measurement system, measurement method, and program described in the embodiment can be understood, for example, as follows:

[0037] (1) The measurement system according to the first embodiment comprises a neutron generator that irradiates an object to be measured with neutrons, a neutron detector that detects neutrons in different energy bands, and a measuring device that generates a neutron spectrum based on the neutron count rate detected by the neutron detector and measures the amount of water and / or hydrogen in the object to be measured based on spectral information of the medium velocity group and above from the neutron spectrum. This allows for the measurement of moisture content and hydrogen content in fuel debris storage containers.

[0038] (2) The measurement system according to the second embodiment is the measurement system of (1), wherein the neutron detector for detecting neutrons in different energy bands is composed of one neutron detector, and neutrons in different energy bands are detected by switching and installing moderators of different thicknesses around the one neutron detector. This allows for the detection of neutrons in different energy bands and the generation of neutron spectra.

[0039] (3) The measurement system according to the third embodiment is the measurement system of (1), wherein the neutron detector for detecting neutrons of different energy bands is composed of a plurality of neutron detectors, one of the plurality of neutron detectors is installed as is, and moderators of different thicknesses are installed around each of the remaining neutron detectors. This allows for the detection of neutrons in different energy bands and the generation of neutron spectra.

[0040] (4) The measurement system according to the fourth embodiment is the measurement system of (2) to (3), wherein the neutron detector for detecting neutrons in different energy bands further includes a fast neutron detector for detecting fast neutrons and / or a neutron detector surrounded by a neutron absorber. The measurement system according to claim 2 or claim 3. This allows for the detection of neutrons in different energy bands and the generation of neutron spectra.

[0041] (5) The fifth aspect of the measurement system is the measurement system of (1) to (4), further comprising a gamma-ray detector for detecting gamma rays, wherein the measurement device estimates the gamma-ray characteristics of the object to be measured based on the gamma rays detected by the gamma-ray detector. This allows for the acquisition of physical property information such as the gamma-ray characteristics and density of the object being measured.

[0042] (6) The measurement system according to the sixth embodiment is the measurement system of (1) to (5), further comprising an X-ray CT device, wherein the measurement device estimates the density of the object to be measured based on the CT value measured by the X-ray CT device. This allows for the acquisition of physical property information, such as the density of the object being measured.

[0043] (7) The measurement system according to the seventh embodiment is the measurement system of (1) to (6), further comprising a weighing scale, wherein the measuring device estimates the water content of the object to be measured based on the water content of the object to be measured and the weight measured by the weighing scale. This allows us to estimate the moisture content of the object being measured.

[0044] (8) The measurement method according to the eighth aspect involves detecting the neutron count rate of the object to be measured using a neutron detector that detects neutrons in different energy bands, generating a neutron spectrum based on the detected neutron count rate using a computer, and measuring the amount of water and / or hydrogen in the object to be measured based on the spectral information of the medium velocity group and above from the neutron spectrum. This allows for the measurement of moisture content and hydrogen content in fuel debris storage containers.

[0045] (9) The program according to the ninth aspect causes a computer to generate a neutron spectrum based on the neutron count rate of the object to be measured detected by a neutron detector that detects neutrons in different energy bands, and to measure the amount of water and / or hydrogen in the object to be measured based on the spectral information of the medium velocity group and above in the neutron spectrum. This allows for the measurement of moisture content and hydrogen content in fuel debris storage containers. [Explanation of Symbols]

[0046] 1. Neutron generator 2. Neutron detector 3. Conveying device 4...container 5...moderator 6. Gamma ray generator 7. Gamma-ray detector 8...Weight scale 10. Measuring device 11...Acquisition part 12...Moisture content estimation section 13...Physical property estimation section 14...Storage section 100... Measurement System 900... Computer 901···CPU 902...Main memory 903...Auxiliary storage device 904... Input / Output Interface 905...Communication Interface

Claims

1. A neutron generator that irradiates the object to be measured with neutrons, Neutron detectors that detect neutrons in different energy bands, A measuring device that generates a neutron spectrum based on the neutron count rate detected by the neutron detector, and measures the amount of water and / or hydrogen in the object to be measured based on the spectral information of the medium velocity group and above in the neutron spectrum, A measurement system equipped with the following features.

2. The neutron detector that detects neutrons in different energy bands consists of a single neutron detector, and detects neutrons in different energy bands by switching and installing moderators of different thicknesses around the single neutron detector. The measurement system according to claim 1.

3. The neutron detector that detects neutrons in different energy bands is composed of multiple neutron detectors, one of which is left in place, and moderators of different thicknesses are placed around each of the remaining neutron detectors. The measurement system according to claim 1.

4. A neutron detector that detects neutrons in the aforementioned different energy bands is, The system further includes a fast neutron detector for detecting fast neutrons and / or a neutron detector surrounded by a neutron-absorbing material, The measurement system according to claim 2 or claim 3.

5. It further includes a gamma-ray detector for detecting gamma rays, The measuring device estimates the gamma-ray characteristics of the object to be measured based on the gamma rays detected by the gamma-ray detector. The measurement system according to claim 1 or claim 2.

6. It is further equipped with an X-ray CT scanner, The measuring device estimates the density of the object to be measured based on the CT value measured by the X-ray CT device. The measurement system according to claim 1 or claim 2.

7. A weighing scale is also included, The measuring device estimates the water content of the object to be measured based on the water content of the object and the weight measured by the weighing scale. The measurement system according to claim 1 or claim 2.

8. The neutron count rate of the object being measured is detected by a neutron detector that detects neutrons in different energy bands. A computer generates a neutron spectrum based on the detected neutron count rate, and measures the amount of water and / or hydrogen in the object being measured based on the spectral information of the medium velocity group and above within the neutron spectrum. Measurement method.

9. On the computer, A neutron detector that detects neutrons in different energy bands generates a neutron spectrum based on the neutron count rate of the object being measured. A process for measuring the amount of water and / or hydrogen in the object to be measured, based on spectral information of the medium velocity group or higher among the neutron spectra, A program that executes the command.

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