JP2016161491A - Device for sampling radioactive material and analytical method of radioactive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform the analysis of a radioactive material locally distributed.SOLUTION: This radioactive material sampling device 1 includes: a radiation detection unit 10; and a radioactive material sampling unit 20. These units are fixed to a ROV100 via a frame 110. For this reason, the radiation detection unit 10 and the radioactive material sampling unit 20 are integrated each other and move on the sea bottom B together with the ROV100. The radiation detection unit 10 recognizes the presence or absence of a radioactive material piece in the sea bottom B, and when the radioactive material pieces are recognized, the soil around the periphery thereof is sampled by a radioactive material sampling unit 20. A radioactive material sampling device control unit recognizes which detection intensity of the radiation detector in each of the measuring heads is the highest, and recognizes a region inner position of the radioactive material piece.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radioactive substance collection device for collecting radioactive substances on the seabed in water and the like, and a radioactive substance analysis method using the same.

  When radioactive materials containing radioactive isotopes are scattered, it is important to measure their distribution. For this purpose, radiation (gamma rays, etc.) emitted by radioactive isotopes can be measured with a radiation detector. It is valid. For example, when radioactive materials scattered from radiation related facilities are targeted, it is clear that such radioactive materials are concentrated near the ground surface on the ground. For this reason, it is particularly important to know the horizontal distribution.

  On the other hand, radioactive material is scattered not only on the ground but also on the sea, and in this case, it accumulates on the sea bottom (water bottom), and, for example, particulate radioactive material pieces exist at specific locations on the sea bottom. In order to measure the distribution of these radioactive material fragments on the sea floor, it is necessary to measure radiation at the sea floor using a small measuring device thrown into the sea, and to perform this remotely from a ship on the sea. Become. Specifically, for example, as described in Patent Document 1, a method of scanning a device on which a radiation detector is mounted on the seabed can be used. Further, as described in Patent Document 2, a method in which a measuring device is dropped into the sea and the measuring device is levitated after measuring radiation on the seabed can be used.

Utility Model Registration No. 3181739 JP 2013-242219 A

  However, in order to detect radioactive material fragments that exist extremely locally in the form of small particles, it has been necessary to make a number of measurements over a wide area on the seabed. That is, it is difficult to perform efficient measurement.

  Furthermore, if a radioactive substance piece is detected by the above method (a narrow area having a high radiation intensity is recognized), it is important to accurately recognize the location. On the ground, it is easy to accurately recognize this location using GPS (Global Positioning System) or the like, but it is difficult to receive GPS signals on the sea floor. It was also difficult to obtain accurate position information accurately.

  Therefore, it has been difficult to efficiently analyze the radioactive material locally distributed in water.

  The present invention has been made in view of such problems, and an object thereof is to detect radioactive substances in water with high accuracy.

In order to solve the above problems, the present invention has the following configurations.
A radioactive substance collecting apparatus according to claim 1 of the present invention is a radioactive substance collecting apparatus that collects a radioactive substance that is locally present in water, and the intensity of radiation in a detection area that is a specific area in plan view. The radiation detection means for measuring, the radioactive substance collection means for collecting the substance in the detection area, and the detection intensity of the radiation detected by the radiation detection means exceeds a first threshold value determined for the radiation detection means. Control means for controlling the radioactive substance collection means to collect the substance in the detection region, and the radiation detection means and the radioactive substance collection means can move in water in conjunction with each other. It is characterized by that.
In this invention, when the radiation detection unit recognizes that a radioactive substance is present in a specific detection area in water, the substance in the detection area is collected by the radioactive substance collecting means. At this time, the radiation detection means and the radioactive substance collection means can be moved in conjunction with the water in which the distribution of the radioactive substance is to be measured.
The radioactive substance sampling apparatus according to claim 2 of the present invention includes an in-area position estimation means for estimating an in-area position, which is a position where the radioactive substance emitting the radiation exists in the detection area, and the control means Is characterized in that the radioactive substance collecting means collects a substance at a position in the region.
In the present invention, the position (intra-area position) of the radioactive substance in the detection region is estimated, and the substance at this position is selected and collected by the radioactive substance collecting means. The in-region position estimated here is a relative positional relationship of the radioactive substance with respect to the radiation detecting means, and is not an absolute position coordinate of the detected radioactive substance.
In the radioactive substance sampling apparatus according to claim 3 of the present invention, a plurality of radiation detectors discretely arranged on a plane are used in the radiation detection means, and the in-region position estimation means includes a plurality of the radiations. The position in the region is estimated from the positional relationship of the radiation detector with the maximum detection output among the detectors with respect to the detection region.
In the present invention, the position in the area is estimated based on the positional relationship between the detection area and the radiation detection intensity of the plurality of radiation detectors used in the radiation detection means.

The radioactive substance sampling apparatus according to claim 4 of the present invention is characterized in that a plurality of the radiation detectors arranged one-dimensionally are used in the radiation detection means.
In the present invention, a plurality of radiation detectors arranged one-dimensionally are used in the radiation detection means.
In the radioactive substance sampling apparatus according to claim 5 of the present invention, the radiation detecting means performs two measurements in which a plurality of the radiation detectors are arranged one-dimensionally so that the arrangement directions of the radiation detectors intersect each other. And the detection area is defined by a section in which the radiation detectors are arranged in each of the two measurement heads, and the in-area position estimation means outputs the detection output in each of the two measurement heads. The position in the region is estimated from the position of the radiation detector having the maximum value in the measurement head.
In the present invention, two intersecting measurement heads are used in the radiation detection means, and the detection area is defined by the measurement heads. The in-region position is estimated based on the position of the radiation detector at which the detection intensity in each of the two measurement heads is maximized.
In the radioactive substance sampling device according to claim 6 of the present invention, in the radiation detection means, a plurality of the radiation detectors arranged in a ring shape in a plan view are used, and the detection region is formed by a plurality of the radiation detectors. It is an enclosed area.
In the present invention, an annularly arranged radiation detector is used as the radiation detecting means. Further, the detection area is an area surrounded by the plurality of radiation detectors.
In the radioactive substance sampling device according to claim 7 of the present invention, the radiation detector includes a scintillator that emits light by absorbing the radiation, and a photodiode that detects light emitted by the scintillator. And
In the present invention, a radiation detector in which a scintillator and a photodiode are combined is used.

The radioactive substance sampling apparatus according to claim 8 of the present invention includes apparatus position recognition means for recognizing an apparatus position that is the position of the radiation detection means, and the control means is based on the in-region position and the apparatus position. Recognizing a radioactive substance position which is a position of the radioactive substance emitting the radiation.
In the present invention, the apparatus position, which is the absolute position of the radiation detection means, is recognized by the apparatus position recognition means. For this reason, the absolute position (radioactive material position) where it is presumed that the radioactive material is present is estimated based on the device position and the position in the region.
According to a ninth aspect of the present invention, there is provided a radioactive substance collecting apparatus comprising a radioactive substance position storage means for storing the radioactive substance position.
In the present invention, the radioactive substance position is stored by the radioactive substance position storage means. For this reason, simultaneously with the collection of the radioactive substance, information on the position (absolute position) where the radioactive substance was present is stored in the radioactive substance collection apparatus.
In the radioactive substance collecting apparatus according to claim 10 of the present invention, the radioactive substance collecting means includes a flexible suction hose for sucking the substance in the detection region, and the suction port of the suction hose is the region. It is controlled to the inner position.
In the present invention, the substance at the position in the detection region is sucked by the flexible suction hose.
The radioactive substance collection device according to claim 11 of the present invention comprises a sample confirmation means for measuring the intensity of radiation emitted from the substance in the detection region collected by the radioactive substance collection means, and the control means comprises When the detection intensity of the radiation detected by the sample confirmation unit is equal to or less than a second threshold value predetermined for the sample detection unit, the substance in the detection region is again sent to the radioactive substance collection unit. It is characterized by performing control for acquisition.
In the present invention, the presence or absence of a radioactive substance in the collected substance is determined. If it is determined that the radioactive substance is not present, the substance is collected again.
The radioactive substance sampling apparatus according to claim 12 of the present invention is characterized in that a multichannel analyzer (MCA) and / or a multichannel scaler (MCS) is connected to the output of the radiation detection means.
In the present invention, by using a multi-channel analyzer (MCA) and a multi-channel scaler (MCS), it is possible to simultaneously measure radiation intensities of a plurality of types of energy.
According to a thirteenth aspect of the present invention, there is provided a radioactive substance collection device that is movable along the bottom of the water.
In the present invention, since the radioactive substance collection device can be moved along the bottom of the water, the radioactive substance collection device can scan the bottom of the water.

The radioactive substance analysis method according to claim 14 of the present invention is characterized in that the radioactive substance contained in the substance in the detection region collected using the radioactive substance collection apparatus is analyzed.
In the present invention, the radioactive material collected using the radioactive material collection device is analyzed on the ground or the like.
In the radioactive substance analysis method according to claim 15 of the present invention, the substance in the detection region is sampled at each of a plurality of measurement locations in water using the radioactive substance sampling device, and the samples are collected at the plurality of measurement locations. The distribution of the radioactive substance contained in the substance in the detection region at the bottom of the water is measured.
In the present invention, substances in the detection region are collected at each of a plurality of measurement locations. This measures the distribution of radioactive material at the bottom of the water.
In the radioactive substance analysis method according to claim 16 of the present invention, the substance in the detection region is sampled at a plurality of measurement locations in water using the radioactive substance sampling device, and the radioactive substance position at a plurality of measurement locations. Based on the plurality of radioactive substance positions stored in the storage means, the distribution of the radioactive substance contained in the substance in the detection region collected at each of the plurality of measurement locations is measured at the bottom of the water.
In the present invention, not only substances in the detection region are collected at a plurality of measurement locations, but also the radioactive substance positions at each of the plurality of measurement locations are recognized. This measures the distribution of radioactive material at the bottom of the water.
A radioactive substance analysis method according to claim 17 of the present invention measures the intensity of radiation in a plurality of detection regions corresponding to a plurality of measurement locations using the radiation detection means in the radioactive substance sampling apparatus, The first threshold value is set such that the substance in the detection area having the highest detected intensity of the detected radiation among the plurality of detection areas corresponding to the measurement location is collected by the radioactive substance collecting means. The substance in the detection region where the intensity of the detected radiation is the highest is collected using the radioactive substance collecting means, and the radioactive substance contained in the collected substance is analyzed.
In the present invention, in the radioactive substance sampling apparatus, first, measurement is performed in a plurality of detection regions corresponding to a plurality of measurement locations using only radiation detection means. The first threshold value is set based on the detection intensity in the detection area where the detection intensity of the radiation is highest among the detection areas where the measurement is performed. Thereafter, the substance in the detection region is collected using the radioactive substance collecting means.
In the radioactive substance analysis method according to claim 18 of the present invention, the radioactive substance collection device is fixed to a moving body that moves in water, and the radioactive substance collection device is moved between the plurality of measurement points on the bottom of the water. And
In the present invention, the radioactive substance is collected at a plurality of measurement locations by scanning the radioactive substance collection apparatus at the bottom of the water using a moving body.
The radioactive substance analysis method according to claim 19 of the present invention is characterized in that the moving body is a remote control unmanned spacecraft (ROV).
In the present invention, the above-described movement is performed using a remotely operated unmanned explorer (ROV).

Since the radioactive substance collecting apparatus of the present invention is configured as described above, it is possible to collect small radioactive substance pieces that are locally present particularly at the bottom of the water with high efficiency. Etc., and can be performed with high accuracy.
At this time, by using the intra-region position estimation means, a small radioactive substance piece can be collected more efficiently at the intra-region position. In addition, by using a combination of the position in the area (relative position of the radioactive substance piece in the detection area) and the apparatus position (absolute position of the radiation detection means, etc.), the absolute presence of the collected radioactive substance piece was present. The correct position can be recognized accurately. In addition, the distribution of radioactive material can be obtained accurately.
In addition, by using a one-dimensionally arranged radiation detector in the radiation detection means, it is possible to estimate the position of the radioactive substance piece in the area with a simple configuration. It can be done more easily. By adopting such a simple configuration of the radiation detection means, the radiation detection means can be made small and light, and its movement (scanning) becomes easier. In particular, if a radiation detector that combines a scintillator and a photodiode is used, each radiation detector can be made small and light, and the radiation detector can be operated even with a low-output power source. It is particularly preferable when used in the above.
In addition, when a flexible suction hose that can easily change the position of the suction port is used, it is particularly easy to selectively suck the substance at the position in the region where the radioactive substance piece is estimated to exist. Can be done. When the sample confirmation means is used, the radioactive substance piece can be collected more reliably.
Further, by using MCA or MCS in the radiation detection means, it is possible to selectively collect a radioactive substance containing a specific nuclide or to recognize a nuclide contained in a radioactive substance recognized as existing.

Moreover, in the radioactive substance analysis method of the present invention, the collected radioactive substance piece can be analyzed with high accuracy on the ground by using the above-described radioactive substance sampling apparatus, and the distribution state thereof is also accurately checked. be able to. In particular, such a radioactive substance analysis method is suitable for examining a radioactive substance in water (in the sea) where it is difficult to collect a radioactive substance piece and to determine its exact position.
At this time, first, the radiation intensity is detected at a plurality of measurement locations using only the radiation detection means, the first threshold value is set based on the radiation intensity at the measurement location where the highest radiation intensity is obtained, and then the radioactive substance is again formed. If the collection means collects a substance in the detection region, soil with particularly high radiation intensity can be collected selectively and efficiently.
In this case, by combining the ROV with this radioactive substance collection device, it is possible to accurately and easily collect the radioactive substance pieces in water or the like.

It is a figure which shows the form at the time of using the radioactive substance sampling device which concerns on embodiment of this invention. It is the side view (a) and top view (b) which show the structure of the radiation detection means in the radioactive substance sampling apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of the radioactive substance collection | recovery means in the radioactive substance collection apparatus which concerns on embodiment of this invention. It is a figure which shows the connection of ROV etc. with the structure of the radioactive substance sampling apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of the modification of the radiation detection means and radioactive substance collection means in the radioactive substance collection apparatus which concerns on embodiment of this invention.

  Hereinafter, a radioactive substance collection device and a radioactive substance analysis method according to embodiments of the present invention will be described. This radioactive substance collecting apparatus is preferably used for measuring radioactive substances that are present locally locally on the seabed. This radioactive substance collection device is used by being mounted (fixed) on a moving body such as a ROV (Remotely Operated Vehicle). For this reason, this radioactive substance sampling apparatus can move on the seabed together with the moving body.

  FIG. 1 shows a configuration when the radioactive substance collection apparatus 1 is used while being fixed to the ROV 100. The ROV 100 is mounted in a bowl-shaped frame 110 provided to protect the ROV 100 around the ROV 100, and the ROV 100 is placed under the sea surface S. When the frame 110 reaches the sea bottom B, the position of the ROV 100 is changed to the sea bottom. Determined for B. However, the ROV 100 can move on the seabed B in this state.

  The radioactive substance collection device 1 includes a radiation detection unit (radiation detection means) 10 and a radioactive substance collection unit (radioactive substance collection means) 20. These are fixed to the ROV 100 via the frame 110. For this reason, the radiation detection unit 10 and the radioactive substance collection unit 20 are integrated and move on the seabed B together with the ROV 100. Note that a radioactive substance collection device control unit (control means) 30 described later is mounted in the radioactive substance collection unit 20. The radiation detection unit 10 recognizes the presence or absence of radioactive material pieces (regions with high radiation intensity locally) on the seabed B, and when the radioactive material pieces are recognized, the radioactive material collection unit 20 together with the surrounding soil and seawater. Collect by.

  FIG. 2 is a side view (a) and a top view (b) showing the configuration of the radiation detection unit 10. Here, the side view and the top view correspond to a state when the radiation detection unit 10 is actually used. The radiation detection unit 10 includes a base 11 and measurement heads 12 </ b> A and 12 </ b> B that intersect at a 90 ° angle at a connecting portion with the base 11. The plane including the longitudinal direction of the heads 12A and 12B is configured to overlap with or close to the seabed B on which the radiation detection unit 10 is placed. In the measurement heads 12A and 12B, as schematically shown in FIG. 2B, twelve radiation detectors 121 are arranged in the longitudinal direction.

  Here, since the measurement heads 12A and 12B intersect at an angle of 90 °, the longitudinal direction of the heads 12A and 12B corresponds to each of the 12 radiation detectors 121 as shown in FIG. 2B. It is possible to set a detection region R formed by a virtual lattice on a plane including the. In FIG. 2B, it is assumed that the radioactive substance piece P exists at the illustrated position in the detection region R. In this case, the radiation intensities detected by the twelve radiation detectors 121 in the measurement head 12A and the radiation intensities detected by the twelve radiation detectors 121 in the measurement head 12B are shown in FIG. It is schematically shown adjacent to the measuring heads 12A, 12B. That is, when the radioactive substance piece P exists at the illustrated position on the lattice, the radiation emitted from the radioactive substance piece P is detected by the radiation detector 121 in the measurement head 12A and the radiation detector 121 in the measurement head 12B. In the measurement head 12A, the fifth radiation detector 121 from the left provided at the closest distance to the radioactive substance piece P, and in the measurement head 12B, the sixth from the left provided at the closest distance to the radioactive substance piece P. The detection intensity at the radiation detector 121 is the highest. That is, it is estimated that the radioactive substance piece P exists at the position corresponding to the position of the radiation detector 121 having the highest detection intensity in the measurement head 12B and the position of the radiation detector 121 having the highest detection intensity in the measurement head 12B. be able to.

  If the radioactive substance piece P exists in the detection region R shown in FIG. 2B, at least one of the radiation detectors 121 in the measurement head 12A and at least one of the measurement heads 12B. The detection intensity of the radiation detector 121 is increased. For example, when the radioactive substance piece P exists on the upper side of the measurement head 12A in FIG. 2B, the detection intensity in any of the radiation detectors 121 in the measurement head 12A is increased, but the radioactive substance piece P Since the emitted radiation is blocked by the measurement head 12A, the detection intensity of any radiation detector 121 in the measurement head 12B does not increase. Therefore, a threshold value (first threshold value) is set for the detection intensity in the radiation detector 121, and at least one of the radiation detectors 121 in the measurement head 12A and at least one of the radiation detectors 121 in the measurement head 12B. If the detected intensity exceeds the threshold value, it can be estimated that the radioactive substance piece P exists somewhere in the detection region R. Hereinafter, the case where the detection intensity of the radiation detector 121 or the like exceeds this threshold is referred to as “radiation detected”.

  Here, the length of the measurement heads 12A and 12B can be set to about 30 cm, for example. In this case, due to the above configuration, even when a small radioactive substance piece P having a size of, for example, 1 cm or less exists in the detection area R of 30 cm square, the radioactive substance piece P exists in the detection area R. It is possible to recognize this and to estimate the position (in-area position) within the detection area R. Here, this position is a relative position with respect to the measurement heads 12A and 12B (radiation detection unit 10).

  When it is recognized that the radioactive substance piece P is present in the detection region R, the radioactive substance collecting unit 20 sucks the substance in the area where the radioactive substance piece P is estimated to exist as described above. If the positional relationship between the radioactive substance collection unit 20 and the radiation detection unit 10 is fixed, even if the absolute positional information of the radioactive substance piece P is unknown, such control is possible if the position in the region is found. . Here, although the radioactive substance piece P is mixed in the soil of the seabed B, not only the soil of the seabed B but also seawater is sucked simultaneously. FIG. 3 is a diagram showing the configuration of the radioactive substance collection unit 20. In the radioactive substance collecting unit 20, the soil on the seabed B is sucked together with seawater by a suction pump 22 from a flexible suction hose 21. The position of the suction port 21A at the tip of the suction hose 21 is adjusted by a manipulator 23 (not shown in FIG. 3) shown in FIG. The sucked substance is separated into soil having a large specific gravity and seawater having a low specific gravity by the separation unit 24, and the seawater is again discharged into the sea from the seawater discharge unit 25 on the upper side. On the other hand, the soil containing the radioactive substance piece P is stored in a state of being settled in the lower sample tank 26.

  Here, the sample tank 26 is provided with a sample confirmation radiation detector (sample confirmation means) 27 for detecting the radiation emitted by the substance in the sample tank 26, similarly to the radiation detector 121. Similarly to the radiation detector 121 described above, when the detection intensity of the sample confirmation radiation detector 27 exceeds a second threshold value determined in advance for the sample confirmation radiation detector 27, the sample tank 26 is radioactive. It can be recognized that the substance exists, that is, the radioactive substance piece P is collected in the sample tank 26.

  FIG. 4 is a diagram showing a configuration of a control system in the configuration of FIG. 1 including the radiation detection unit 10 and the radioactive substance collection unit 20 described above. Here, the configuration in the ship 300 used for controlling the ROV 100 is also shown. In FIG. 4, only the ship 300 is on the sea (the upper side of the sea surface S), and the others are in the sea (the lower side of the sea surface S).

  The ship 300 is provided with an overall control unit 301 that is operated by an operator and performs overall control, and a power source 302 that supplies electric power thereto. As the overall control unit 301, for example, a personal computer or the like can be used. Further, since the ship 300 is located on the sea, it is possible to accurately recognize its own position by receiving GPS signals. A position information acquisition unit 303 having such a function is also mounted on the ship 300, and the overall control unit 301 can recognize this position.

  Exchange of control signals and the like between the ROV 100 side and the ship 300 (overall control unit 301) is performed in seawater via the optical fiber 304. Electric power is supplied to the components in the ROV 100, the radiation detection unit 10, and the radioactive substance collection unit 20 by the ROV side power source 101 provided in the ROV 100, and the ROV 100 is operated by a power source different from the ship 300. In addition, the ROV 100 itself and the radioactive substance collection device (the radiation detection unit 10 and the radioactive substance collection unit 20) are controlled by the ROV control unit 102 mounted on the ROV 100. The ROV 100 can move on the seabed B, and this control is also performed by the ROV control unit 102.

  The operation of the ROV 100 in the sea is controlled by the ROV control unit 102. For this reason, the output of the sensor unit 103 is input to the ROV control unit 102. The sensor unit 103 includes a depth sensor for recognizing the depth of the ROV 100, an acceleration sensor for recognizing movement acceleration, a posture sensor for recognizing posture, a salinity meter for recognizing the state of seawater, and the like. Further, as described above, accurate position information of the ship 300 is input to the ROV control unit 102 from the ship 300 side. For this reason, if the position of the ROV 100 in the initial state with respect to the ship 300 is accurately recognized, the ROV control unit 102 can recognize the accurate position of the ROV 100 even when the ROV 100 moves thereafter. In addition, an inertial navigation device or a Doppler sonar may be used to recognize the exact position of the ROV 100.

  The movement / posture control thruster 104 is a power engine for moving the ROV 100 on the seabed B or controlling the posture (direction) thereof. The ROV control unit 102 can move the ROV 100 on the seabed B using the movement / posture control thruster 104 in accordance with a signal from the ship 300 side and control the posture (direction) of the ROV 100. At this time, the radiation detection unit 10 and the radioactive substance collection unit 20 fixed to the ROV 100 via the frame 110 also move simultaneously. For this reason, the ROV control unit 102 can also move the radiation detection unit 10 and accurately recognize the position and orientation of the radiation detection unit 10 by the sensor unit 103.

  The radiation detector 121 provided in the measurement heads 12A and 12B in the radiation detection unit 10 can detect the radiation (characteristic γ rays and the like) emitted from the radioactive substance piece P to be detected, and as this power source Any device that can use the ROV-side power supply 101 can be used. For example, a radiation detector 121 that combines a scintillator that emits light in the visible light region by absorbing radiation, a photodiode that detects the visible light, and the like can be used. As the scintillator, for example, a CsI (Tl) crystal having a side of about 1 cm is used. Each photodiode is also connected to a preamplifier that amplifies the detection signal.

In this case, the radiation absorbed by the scintillator is recognized as a pulse at the output of the photodiode, and its pulse height corresponds to the energy of the radiation. For this reason, the output of the radiation detector 121 is input to an MCA (multichannel analyzer) 122 provided in the base 11 in FIG. 2, and by using the MCA 122, the radiation for each of a plurality of types of energy can be counted. it can. Thereby, for example, a specific nuclide emitting gamma rays of this energy can be selectively detected by counting gamma rays of a specific energy, for example, 511 keV, ¹³⁷ Cs corresponding to characteristic gamma rays emitted by ²² Na. The intensity of 662 keV gamma rays corresponding to the characteristic gamma rays emitted by can be separately detected by the single radiation detector 121. Further, the detection intensity (count number) data for each energy in the detection output of the radiation detector 121 is transmitted to the overall control unit 301 at sea via the ROV control unit 102, and the operator recognizes the radioactive substance piece P recognized. The radionuclide contained in can be recognized. In addition, as the radiation detector 27 for sample confirmation provided in the radioactive substance collection part 20, the thing of the structure similar to the radiation detector 121 can be used.

  In addition to the MCA 122 or in place of the MCA 122, an MCS (multi-channel scaler) can be used. In this case, it is possible to detect a temporal change in the detection spectrum (output pulse height distribution) of the radiation detector 121. For this reason, in addition to being able to perform the same analysis as described above, the ROV control unit 102 performs control to move the ROV 100 to a position where the detection intensity is higher than the measurement result of the radiation detector 121 while the ROV 100 is moving, for example. Is also possible.

  Further, a radioactive substance collection device control unit (control means) 30 for controlling the operation of the radioactive substance collection unit 20 and the radiation detection unit 10 is provided. As described above, the radioactive substance collection device control unit 30 is actually provided in the radioactive material collection unit 20, but the radioactive substance collection device control unit 30 may be installed in the radiation detection unit 10 or the ROV 100. Alternatively, the ROV control unit 102 may also serve as the radioactive substance collection device control unit 30.

  The output of each radiation detector 121 via the MCA 122 is input to the radioactive substance collection device control unit 30. As described above, it is recognized that the radioactive substance piece P exists in the detection region defined by the measurement heads 12A and 12B, and the radiation detector 121 in the measurement head 12A has the maximum detection intensity, When there is a radiation detector 121 having the maximum detection intensity among the radiation detectors 121 in the measurement head 12B, the radioactive substance sampling device control unit 30 detects which radiation detector 121 has a detection intensity in each of the measurement heads 12A and 12B. And the position in the region of the radioactive substance piece P is recognized.

  Information on the position and orientation of the radiation detection unit 10 is input to the radioactive substance collection device control unit 30 via the ROV control unit 102. For this reason, the radioactive substance sampling device control unit 30 also functions as device position recognition means for recognizing the position (device position) of the radiation detection unit 10. For this reason, after all, the radioactive substance sampling apparatus control unit 30 can recognize the position where the radioactive substance piece P is estimated to exist from the apparatus position and the in-region position. The position of the radioactive substance piece P recognized here (radioactive substance position) is an absolute position based on a GPS signal or the like. This radioactive substance position is stored in a radioactive substance position storage unit (radioactive substance storage means) 31 constituted by a nonvolatile memory or the like. Thereby, in this radioactive substance collection device 1, the radioactive substance piece P is collected, and at the same time, the position where the radioactive substance piece P exists is also stored in the radioactive substance position storage unit 31.

  The radioactive substance collecting unit 20 is provided with a manipulator 23 that is locked to the suction hose 21 and can move the position of the water suction port 21A of the suction hose 21 on a plane according to the position of the tip. When the radiation detector 121 having the maximum intensity as described above is recognized, the radioactive substance sampling device control unit 30 causes the suction port of the suction hose 21 to be located at the position of the radioactive substance piece P estimated thereby. Next, the manipulator 28 is controlled. Thereafter, the detector control unit 27 can store the soil in the region including this position in the sample tank 25 by turning on the suction pump 22.

  At this time, when the radiation detector 27 for sample confirmation detects radiation, the radioactive substance collection device control unit 30 can recognize that the radioactive substance piece P is accommodated in the sample tank 26, and to that effect, The position (or in-region position) of the radioactive substance P can be transmitted to the overall control unit 301 on the sea via the ROV control unit 102. If the radiation detector 27 for sample confirmation fails to detect radiation, it recognizes that the collection of the radioactive substance piece P has failed, and the radioactive substance collection apparatus control unit 30 sucks the same place again, or Operations such as sequentially sucking adjacent regions can be performed. This operation is repeated until the sample confirmation radiation detector 27 detects radiation. If the sample confirmation radiation detector 27 fails to detect radiation even when this operation is performed a predetermined number of times, the radioactive substance sampling is performed. The device control unit 30 can notify the ocean control unit 301 via the ROV control unit 102 to that effect. In addition, when the nuclide confirmed by the radiation detector for sample confirmation 27 and the nuclide confirmed by the radiation detector 121 of the radiation measuring instrument 10 are different, the soil can be collected again. Alternatively, it is not necessary to cause only the entire control unit 301 to notify that fact and to re-collect the soil.

  Further, when the radiation detector 121 in the measurement heads 12A and 12B detects radiation, but there are a plurality of peaks in the detected intensity, the fact is notified to the overall control unit 301 at sea via the ROV control unit 102. The general control unit 301 can receive an instruction as to which peak is to be sucked. Further, when the radiation detector 121 in the measurement heads 12A and 12B detects the radiation, but a uniform detection intensity is obtained in at least one of the measurement heads 12A and 12B and no peak is recognized, FIG. It is recognized that the radioactive material is uniformly distributed over a wide range in the lattice region of (b), and that fact can be transmitted to the overall control unit 301 on the sea via the ROV control unit 102. In this case, it is possible to collect the soil in the same manner from a region where it is recognized that at least the radioactive substance is distributed.

  When it is recognized that the radioactive substance piece P is accommodated in the sample tank 26, an operator in the ship 300 can know this and the position of the radioactive substance piece P based on information from the overall control unit 301. . Thus, the operator can operate the overall control unit 301 to collect the ROV 100 and the like, and then collect the soil containing the radioactive material piece P from the radioactive material collection unit 20 (sample tank 26). Then, the analysis of this soil (radioactive substance piece) can be performed on the ground by various analysis methods.

  Then, the same operation | work is each performed in a several measurement location, and the substance (soil) in which the radioactive substance piece P is contained in each measurement location can be extract | collected. This substance can be taken out from the sample tank 26 on the ground, and analysis (composition analysis etc.) of the radioactive substance piece P (radioactive substance) can be performed again. At this time, the distribution of the radioactive substance on the seabed B can be measured from the analysis results obtained at a plurality of measurement locations. At this time, this distribution can be obtained with high accuracy by using the radioactive substance position stored in the radioactive substance position storage unit 31.

  Alternatively, in the case where a plurality of sample tanks 26 are provided in the radioactive substance collecting unit 20 and the soil sucked in each measurement location is sequentially accommodated in each sample tank 26, and the radioactive substance pieces P are accommodated in all the sample tanks 26. , ROV100 can also be recovered at sea. At this time, the radioactive substance position obtained for each measurement location is stored in the radioactive substance position storage unit 31 in association with each sample tank 26, whereby the distribution of the radioactive substance can be obtained easily and with high accuracy.

  In the radiation detection unit 10 described above, the measurement heads 12A and 12B intersecting each other are used in order to recognize that the radioactive substance piece P exists in the detection region R in FIG. However, as the radiation detection unit, a configuration other than that shown in FIG. 2 can be used as long as it can recognize that the radioactive substance piece P exists in a specific region (detection region) that can be sucked. For example, in the configuration of FIG. 2, only one of the measurement heads 12 </ b> A and 12 </ b> B may be moved back and the set angle with respect to the base 11 may be switched. Even in such a configuration, if the position of the radioactive substance piece P does not fluctuate with time, the presence / absence of the radioactive substance piece P and its position are estimated using the detection results before and after switching the angle in the same manner as described above. be able to. Further, a similar operation can be performed by using a single radiation detector and scanning it along the longitudinal direction of the measurement heads 12A and 12B in FIG. In such a case, the number of radiation detectors can be reduced and the detection region R can be set similarly to FIG.

  Alternatively, an array type radiation detector in which pixels (pixels) capable of detecting radiation are two-dimensionally arranged can be used. In this case, the radioactive substance position or the distribution of the radioactive substance can be obtained more accurately. However, in this case, it is necessary to move the arrayed radiation detector in order to suck the soil where the pixel estimated to be closest to the radioactive substance piece P is present. Further, in this case, processing of the detection signal becomes complicated, and therefore a processing unit corresponding to this needs to be mounted on the radiation detection unit.

  Moreover, as a radioactive substance detection part, as shown in FIG. 5, the thing of the structure which has arrange | positioned the radiation detector 121 circularly in planar view can be used. In this case, the manipulator is not used, and the suction port 21A in the suction hose 21 has a circular shape, so that the soil of a wide and wide area (detection area R) corresponding thereto can be sucked. A plurality of radiation detectors 121 are arranged on the outer periphery (circumference) of the detection region R. In this case, when all the arranged radiation detectors 121 detect radiation, it can be recognized that the radioactive substance piece P exists in the detection region R.

  Even in this case, the detection output of the radiation detector 121 closest to the radioactive substance piece P is the highest. For example, by analyzing the ratio between the detection output and the detection output of the radiation detector 121 at a position facing the radiation detector 121, the position (intra-region position) of the radioactive substance piece P in the detection region R is determined. Can be estimated.

  For this reason, if it is set as the structure which can move the suction port 21A and the some radiation detector 121 on the seabed B interlockingly, the position of the radioactive substance piece P can be calculated | required similarly to the above, and this can be extract | collected. In this case, both the suction hose 21 (radioactive substance collection unit) and the radiation detector 121 (radiation detection unit) move on the seabed B as the ROV 100 moves without using the manipulator. Accordingly, the radioactive substance collecting device can scan the seabed B. Further, the sample can be taken by moving the suction port 21A so as to face the position of the radioactive substance piece P without moving the ROV 100. Or it is good also as a structure which uses the manipulator and the some radiation detector 212 moves in the state which maintained the structure of FIG. 5 with the suction hose 21 with the manipulator.

Further, as shown in FIG. 5, in the case of the configuration in which the radiation detectors 121 are arranged in a ring shape, when the detection intensities of all the radiation detectors 121 are equal, the detection region R (suction port 21A) It can be estimated that the radioactive substance piece P exists in the center. For this reason, moving the ROV 100 so as to obtain such a detection output, and performing the suction after the radioactive substance piece P comes to the center of the suction port 21A, thereby collecting the radioactive substance piece P more efficiently. Can do.

  Each radiation detector 121 in the radiation detector 10 is required to be able to recognize the magnitude relationship between the detection intensities between the radiation detectors 121 and whether or not the detection intensity exceeds the first threshold. For example, precise measurement accuracy with respect to the radiation intensity emitted by the radioactive substance piece P is not required. For this reason, as the radiation detector 121, as described above, a small and light combination of a scintillator and a photodiode can be used. Further, the radioactive substance collecting unit 20 has a simple configuration using the suction pump 22 and the like. For this reason, both the radiation detection unit 10 and the radioactive substance collection unit 20 can be made small and light, and it is easy to mount them on the ROV 100 and scan the seabed B.

  In the above configuration, the radioactive substance sampling device control unit 30 controls the radioactive substance sampling unit 20 based on the output of the radiation detection unit 10, the position of the radioactive substance piece P in the detection region R (in the region It functions as all of the in-region position estimation means for estimating the position) and the apparatus position recognition means for obtaining and recognizing the position information of the radiation detection unit 10 from the outside. However, separate components may be used as these means. In this case, where each component is placed in the sea or on the ground can be appropriately set. The same applies to the radioactive substance storage unit 31, and this may be arranged anywhere.

  Further, for example, in the configuration of FIG. 5, the position (intra-region position) of the radioactive substance piece P may not be estimated. Even in this case, for example, if the apparatus position recognition means is provided, the position of the radioactive substance P can correspond to the apparatus position. Even in this case, although the accuracy is low, it is possible to measure the distribution of the radioactive substance.

  In addition, as long as the configuration can recognize the radioactive substance piece P in the area and suck the soil containing the radioactive substance piece P in the area, the radiation detection means, the radioactive substance collection means, etc. The thing of the structure of can be used.

  In the radioactive substance sampling apparatus 1 described above, the substance in the detection region R is sampled according to the first threshold set in the radiation detection unit 10. For this reason, the setting of the first threshold is important and can be determined according to the actual detection intensity in the radiation detector 121. In this case, for example, the radiation detection unit 10 (radioactive material sampling apparatus 1) is moved over a plurality of measurement points without operating the radioactive material sampling unit 20, and the output of the radiation detector 121 during this period is actually monitored. In view of this, the first threshold value can be set. In this case, for example, the first threshold value can be set so that only the substance at the measurement location (detection region R) where the highest detection intensity is obtained is collected by the radioactive substance collection unit 20. After setting the threshold value of 1, the radioactive substance collecting unit 20 can be operated at this measurement location. In addition, a predetermined multiple can be set as the first threshold with reference to the lowest detected intensity at a plurality of measurement locations. In these cases, substance collection may be performed at a plurality of measurement locations (detection regions R). Thereby, it is possible to selectively and efficiently collect only the substance at the measurement location (detection region R) that emits such high radiation. The position of the radioactive substance that emits this radiation (radioactive substance position) can also be determined accurately. Such a measurement is effective, for example, when the background intensity of radiation at the bottom of the water is high. When the background intensity of the radiation is not high, a detection intensity value can be determined in advance and set as the first threshold value.

  With the above-described radioactive substance collection device and radioactive substance analysis method, it is possible to examine in detail the radioactive substance that exists locally on the seabed and its distribution. However, it is clear that radioactive substances can be measured not only at the seabed but also at places with similar conditions to the seabed, such as lake bottoms. Furthermore, the same measurement can be performed in places where it is difficult for an investigator to enter, not on the bottom of the water but on the ground.

  As described above, the radioactive substance collection device and the radioactive substance analysis method described above are effective when measuring radioactive substances present in various places in water. It is extremely effective in a wide area.

1 Radioactive material sampling device 10 Radiation detection part (radiation detection means)
11 Base 12A, 12B Measuring head 20 Radioactive substance collecting part (Radioactive substance collecting means)
21 Suction Hose 21A Suction Port 22 Suction Pump 23 Manipulator 24 Separation Unit 25 Seawater Discharge Unit 26 Sample Tank 27 Sample Confirmation Radiation Detector (Sample Confirmation Means)
30 Radioactive material sampling device control unit (control means, in-region position estimation means, device position recognition means)
31 Radioactive substance position storage unit (radioactive substance storage means)
100 Remotely operated unmanned spacecraft (ROV)
DESCRIPTION OF SYMBOLS 101 ROV side power supply 102 ROV control part 103 Sensor part 104 Thruster 110 for movement / attitude control Frame 121 Radiation detector 122 Multichannel analyzer (MCA)
300 Ship 301 Overall Control Unit 302 Power Supply 303 Position Information Acquisition Unit 304 Optical Fiber B Seabed P Radioactive Material Fragment R Detection Area S Sea Surface

Claims (19)

A radioactive substance collecting device for collecting radioactive substances present locally in water,
Radiation detection means for measuring the intensity of radiation in a detection region which is a specific region in plan view;
A radioactive substance collecting means for collecting a substance in the detection region;
When the detection intensity of the radiation detected by the radiation detection means exceeds a first threshold defined for the radiation detection means, control is performed to cause the radioactive substance collection means to collect a substance in the detection region. Control means,
The radioactive substance collecting apparatus, wherein the radiation detecting means and the radioactive substance collecting means are movable in association with each other. An in-region position estimation means for estimating an in-region position, which is a position where the radioactive substance emitting the radiation exists in the detection region;
The radioactive substance collecting apparatus according to claim 1, wherein the control means causes the radioactive substance collecting means to collect a substance at a position in the region.   In the radiation detection means, a plurality of radiation detectors arranged discretely on a plane are used, and the in-region position estimation means is the radiation whose detection output has a maximum value among the plurality of radiation detectors. The radioactive substance collection device according to claim 2, wherein the position in the region is estimated from a positional relationship of a detector with respect to the detection region.   The radioactive substance collection apparatus according to claim 3, wherein the radiation detection means uses a plurality of the radiation detectors arranged one-dimensionally. The radiation detection means comprises two measurement heads each having a plurality of the radiation detectors arranged one-dimensionally so that the arrangement directions of the radiation detectors intersect each other.
The detection area is defined by a section in which the radiation detectors are arranged in each of the two measurement heads,
The in-region position estimation means estimates the in-region position from the position in the measurement head of the radiation detector at which the detection output has a maximum value in each of the two measurement heads. Item 5. The radioactive substance collecting apparatus according to Item 4. In the radiation detection means,
A plurality of the radiation detectors arranged in an annular shape in plan view are used,
The radioactive substance collecting apparatus according to claim 3, wherein the detection region is a region surrounded by a plurality of the radiation detectors.   The said radiation detector is equipped with the scintillator which light-emits by absorbing the said radiation, and the photodiode which detects the light which the said scintillator emitted, The any one of Claim 3-6 The radioactive substance collection device as described in the paragraph. Comprising an apparatus position recognizing means for recognizing an apparatus position which is a position of the radiation detecting means,
The said control means recognizes the radioactive substance position which is the position of the radioactive substance which emitted the said radiation from the position in the said area | region and the said apparatus position, The any one of Claim 2 to 7 characterized by the above-mentioned. The radioactive substance collection device described in 1.   The radioactive substance collection device according to claim 8, further comprising a radioactive substance position storage unit that stores the radioactive substance position.   3. The radioactive substance collecting means includes a flexible suction hose for sucking a substance in the detection region, and a suction port of the suction hose is controlled to a position in the region. The radioactive substance collection device according to any one of claims 1 to 9. Comprising a sample confirmation means for measuring the intensity of radiation emitted from the substance in the detection region collected by the radioactive substance collection means,
The control means determines the substance in the detection region as the radioactive substance when the detection intensity of the radiation detected by the sample confirmation means is equal to or less than a second threshold predetermined for the sample detection means. The radioactive substance collection device according to any one of claims 1 to 10, wherein control is performed to cause the collection means to acquire again.   The radioactive substance collection according to any one of claims 1 to 11, wherein a multichannel analyzer (MCA) and / or a multichannel scaler (MCS) is connected to an output of the radiation detection means. apparatus.   The radioactive substance collecting apparatus according to any one of claims 1 to 12, wherein the radioactive substance collecting apparatus is movable along a water bottom.   A radioactive substance analysis method, comprising: analyzing a radioactive substance contained in a substance in the detection region collected using the radioactive substance collecting apparatus according to any one of claims 1 to 13. .   Collecting substances in the detection region at a plurality of measurement locations in water using the radioactive substance sampling device, and at the bottom of the radioactive material contained in the substances in the detection regions collected at the plurality of measurement locations, respectively. The radioactive substance analysis method according to claim 14, wherein the distribution is measured. Using the radioactive substance collection device according to claim 9 to collect the substance in the detection region at each of a plurality of measurement locations in water,
Based on the plurality of radioactive substance positions stored in the radioactive substance position storage means at the plurality of measurement points, the radioactive substance contained in the substance in the detection region collected at each of the plurality of measurement points at the bottom of the water A radioactive substance analysis method characterized by measuring a distribution. Measuring the intensity of radiation in a plurality of detection regions corresponding to a plurality of measurement locations using the radiation detection means in the radioactive substance sampling device according to any one of claims 1 to 13,
Among the plurality of detection regions corresponding to the plurality of measurement locations, the first threshold value is set such that the substance in the detection region having the highest detected intensity of the detected radiation is collected by the radioactive substance collection unit. The substance in the detection region where the intensity of the detected radiation is the highest is collected using the radioactive substance collecting means, and the radioactive substance contained in the collected substance is analyzed. Radioactive material analysis method.   The radioactive substance collection device is fixed to a moving body that moves in water, and the radioactive material collection device is moved between the plurality of measurement locations on the bottom of the water. The radioactive substance analysis method described in the paragraph.   The radioactive substance analysis method according to claim 18, wherein the mobile body is a remotely operated unmanned space probe (ROV).

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