JP2016075628A - Radioactivity concentration measurement device and sorting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radioactivity concentration measurement device capable of obtaining a reliable radioactivity concentration of a measuring object.SOLUTION: A radioactivity concentration measurement device 1 includes: a carrier unit 6 in which a belt 4 of a measuring conveyor 5 moves in a first direction A1 and conveys a measuring object M in the first direction A1; a return unit 7 in which the belt 4 moves in a second direction A2; and a radioactivity concentration measuring instrument 12 for obtaining a measurement/detection value indicating the radioactivity concentration of the measuring object M being conveyed in the first direction A1. The radioactivity concentration measuring instrument 12 is installed in a measuring instrument installation unit 11 between the belt 4 in the carrier unit 6 and the belt 4 in the return unit 7.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a radioactivity concentration measuring apparatus that measures the radioactivity concentration of an object to be measured that contains a radioactive substance and is transferred by a belt conveyor.

  Conventionally, a radioactive waste separation and volume reduction device described in Patent Document 1 is known as a technique in the field of measuring radiation dose. The apparatus includes a transport unit that transports processing waste and delivers the waste from inside the sorting unit to the outside of the sorting unit, and a radioactive dose detection unit that detects a radioactive dose of the processing waste transported by the transport unit. Yes. The radioactive dose detection unit is fixed above the conveyance surface of the conveyance belt.

JP 2013-14743 A

  The radioactive dose detector described in Patent Document 1 is fixed at a predetermined interval above the conveyance surface of the conveyance belt. Therefore, a gap is formed between the processing waste on the conveyor belt and the radioactive dose detector. However, background radiation may enter through this gap and enter the radioactive dose detection unit. Therefore, it has been difficult to obtain a reliable radiation dose of the processing waste from the radioactive dose detector.

  Then, an object of this invention is to provide the radioactive concentration measuring device which can obtain the reliable radioactive concentration of a to-be-measured object.

  In one embodiment of the present invention, in the radioactivity concentration measuring apparatus that includes a radioactive substance and measures the radioactivity concentration of the measurement object transferred by the belt conveyor, the belt of the belt conveyor moves in the first direction, A carrier part for transferring the object to be measured in a first direction, a return part for moving the belt in a second direction opposite to the first direction, and radiation of the object to be measured being transferred in the first direction A radioactivity concentration measuring instrument that obtains a measurement detection value indicating the active density, and the radioactivity concentration measuring instrument is installed in a measuring instrument installation section between the belt in the carrier section and the belt in the return section.

  In this radioactivity concentration measuring apparatus, the measurement object is transferred in the first direction in the carrier portion of the belt conveyor. And while this to-be-measured object is transferred to the 1st direction, the radioactive concentration is measured by the radioactive concentration measuring device. Here, the radioactivity concentration measuring instrument is installed in a measuring instrument installation section between the belt in the carrier section and the belt in the return section. This measuring instrument installation part is formed inside the belt which is ring-shaped. That is, the radioactivity concentration measuring instrument is installed on the inner peripheral surface side of the belt opposite to the outer peripheral surface of the belt on which the object to be measured is placed. Since the object to be measured is not placed on the inner peripheral surface of the belt, it is possible to install the radioactivity concentration measuring instrument close to the object to be measured. According to this installation, since the gap between the radioactivity concentration measuring instrument and the object to be measured is reduced, the incidence of background radiation to the radioactivity concentration measuring instrument is suppressed. Therefore, a decrease in accuracy of the radioactivity concentration detected by the radioactivity concentration measuring instrument is suppressed, and a reliable radioactivity concentration of the measurement object can be obtained.

  A sliding plate may be installed between the radioactivity concentration measuring device and the belt, and the sliding plate may be fixed to the radioactivity concentration measuring device and slide with respect to the belt. According to this configuration, the radioactivity concentration measuring instrument can be brought into contact with the belt moving in the first direction via the sliding plate. Therefore, the radioactivity concentration measuring instrument can be brought closer to the object to be measured, and the radioactivity concentration measurement accuracy can be improved.

  In addition, the radioactivity concentration measuring device uses a shape acquisition unit that obtains the shape of the object to be measured, a weight acquisition unit that obtains the weight of the object to be measured, a shape, a weight, and a measurement detection value. A processing unit that obtains the radioactive concentration of the object, and the carrier unit has a measured object supply unit set on the upstream side and a measured object discharge unit set on the downstream side, and has a shape The acquisition unit and the weight acquisition unit may be installed between the measurement object supply unit and the measurement object discharge unit along the first direction. According to this configuration, since the density of the measurement object can be obtained, the radioactivity concentration can be corrected using the density.

  A sorting device according to another embodiment of the present invention includes the above-described radioactivity concentration measurement device, a first measured object storage unit that stores a measured object after measurement, and a first measured object. The radioactivity concentration acquired by the 2nd to-be-measured object storage part which accommodates the to-be-measured object after the measurement which has a different radioactivity concentration from the to-be-measured object accommodated in an accommodation part, and a radioactivity concentration measuring device And a switching transfer unit that separates the measurement object after the measurement and transfers it to either the first measurement object storage unit or the second measurement object storage unit. According to this separation apparatus, since the radioactive concentration measuring apparatus can obtain a reliable radioactive concentration of the measurement object, the measurement object can be reliably separated.

  ADVANTAGE OF THE INVENTION According to this invention, the radioactive concentration measuring apparatus which can obtain the reliable radioactive concentration of a to-be-measured object is provided.

FIG. 1 is a plan view of a sorting apparatus including a radioactivity concentration measuring apparatus according to an embodiment of the present invention. FIG. 2 is a side view of the radioactive concentration measuring apparatus of FIG. FIG. 3 is a view showing a cross section taken along line III-III in FIG. FIG. 4 is an enlarged side view showing the vicinity of the radioactivity concentration measuring instrument. FIG. 5 is a flowchart showing a sorting process in the sorting apparatus. 6 (a) and 6 (b) are diagrams for explaining the effect of the radioactivity concentration measuring apparatus. (A) part and (b) part of Drawing 7 are figures explaining the radioactivity concentration measuring device concerning a comparative example.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, the sorting device 90 measures the radioactivity concentration of the soil or the like containing the radioactive substance as the measurement object M, and sorts based on the radioactivity concentration. For example, the separation device 90 separates the measurement object M1 having a radioactivity concentration of 8000 Bq / kg or more and the measurement object M2 having a radioactivity concentration of less than 8000 Bq / kg.

  The separation device 90 includes a radioactivity concentration measurement device 1 that measures the radioactivity concentration while transferring the measurement object M, a hopper 91 that supplies the radioactivity concentration measurement device 1 with the measurement object M, and the acquired radioactivity. A damper chute 92 for separating the measurement object M based on the concentration, a low concentration conveyor 94 for transferring the separated measurement object M1 to the low concentration container 93, and the separated measurement object M2 for high concentration. And a high-concentration conveyor 97 that transports the container 96.

  The radioactivity concentration measuring apparatus 1 has a measurement conveyor 5 which is a so-called belt conveyor, and includes a belt 4 from a measurement object supply unit 2 set on the upstream side to a measurement object discharge unit 3 set on the downstream side. The object M to be measured placed thereon is transferred in the first direction A1. Furthermore, the radioactivity concentration measuring apparatus 1 measures the radioactivity concentration of the measurement object M being transferred. The radioactivity concentration measuring apparatus 1 will be described in detail later.

  A hopper 91 is disposed on the upstream side of the radioactivity concentration measuring apparatus 1 and above the measurement object supply unit 2. The hopper 91 supplies the measurement object M supplied from a supply belt conveyor (not shown) to the measurement object supply unit 2.

  A damper chute 92 as a switching transfer unit is disposed on the measurement object discharge unit 3 side of the radioactivity concentration measurement apparatus 1. The damper chute 92 has a Y-shape, and has a receiving port 92a, a low-concentration discharge port 92b, and a high-concentration discharge port 92c. The damper chute 92 receives the measurement object M discharged from the measurement object discharge unit 3 in the reception port 92a, and then transfers the measurement object M1 having a radioactivity concentration less than a predetermined threshold to the low-concentration discharge port 92b. The object to be measured M2 having a radioactive concentration equal to or higher than a predetermined threshold is discharged to the high concentration outlet 92c. In this separation, the measurement object M is distributed to the discharge port to be discharged by a separation valve (not shown) installed between the receiving port 92a, the low-concentration discharge port 92b, and the high-concentration discharge port 92c. . The separation valve operates based on the radioactivity concentration input from the radioactivity concentration measurement device 1.

  Below the low-concentration discharge port 92b, a low-concentration conveyor 94 for transferring the measurement object M1 after measurement to a low-concentration container 93 as a second measurement-object storage unit is disposed. A low concentration container 93 is arranged downstream of the low concentration conveyor 94. Further, below the high concentration outlet 92c, a high concentration conveyor 97 for transferring the measured object M2 after measurement to the high concentration container 96 as the first measured object storage unit is disposed. . A high concentration container 96 is disposed downstream of the high concentration conveyor 97.

  Next, the radioactive concentration measuring apparatus 1 will be described in detail.

  As shown in FIG. 2, the radioactivity concentration measurement apparatus 1 includes a measurement conveyor 5 and various measuring instruments attached to the measurement conveyor 5. The measurement conveyor 5 includes a carrier portion 6 in which the belt 4 moves in the first direction A1 and a return portion 7 in which the belt 4 moves in a second direction A2 opposite to the first direction A1. Yes.

  The carrier unit 6 is an area where the measurement unit 8 measures the radioactivity concentration of the measurement object M supplied by the measurement object supply unit 2 and transfers it to the measurement object discharge unit 3. The carrier part 6 is located above the return part 7. The carrier unit 6 includes a measurement object supply unit 2, a measurement unit 8, a transfer unit 9, and a measurement object discharge unit 3 which are set in order from the upstream side along the first direction A <b> 1. .

  The return unit 7 is an area in which the belt 4 moves from the pulley 13b disposed on the measured object discharge unit 3 side of the measurement conveyor 5 to the pulley 13a disposed on the measured object supply unit 2 side. Therefore, the belt 4 in the return portion 7 moves in the reverse direction (second direction A2) with respect to the belt 4 in the carrier portion 6. That is, the second direction A2 may be any direction as long as it moves from the pulley 13b arranged on the measured object discharge unit 3 side to the pulley 13a arranged on the measured object supply unit 2 side. It may be diagonally upward. That is, when viewed from the normal direction of the belt 4, the second direction A2 may be opposite to the first direction A1.

  Between the belt 4 in the carrier unit 6 and the belt 4 in the return unit 7, a measuring instrument installation unit 11 is set. In other words, the measuring instrument installation unit 11 is set inside the locus of the belt 4 that is ring-shaped. The measuring instrument installation unit 11 is a part where a later-described radioactivity concentration measuring instrument 12 is installed, and is set between the measured object supply unit 2 and the measured object discharge unit 3 along the first direction A1. ing. Further, in the measuring instrument installation unit 11, the distance D1 between the belts 4 is larger than the diameter of the pair of pulleys 13a and 13b installed at both ends of the measurement conveyor 5. More specifically, in the measuring instrument installation unit 11, the distance D <b> 1 between the belt 4 that moves the carrier unit 6 and the belt 4 that is positioned below the belt 4 of the carrier unit 6 and moves the return unit 7. Has been expanded. In other words, the distance between the inner peripheral surfaces 4b of the ring-shaped belt 4 is widened in the direction along the normal direction of the belt surface. This distance D <b> 1 only needs to be large enough to allow the radioactive concentration measuring instrument 12 to be installed, and may have a size that allows an operator to enter between the belts 4. According to such a distance D1, the installation work etc. of the radioactive concentration measuring instrument 12 can be implemented easily.

  In the measurement conveyor 5, the belt 4 is stretched between a pulley 13a disposed at the upstream end and a pulley 13b disposed at the downstream end, and a plurality of rollers are disposed between the pulleys 13a and 13b. The plurality of rollers include a support roller 16 that supports the belt 4 in the transfer unit 9 and a bypass roller 17 that bypasses the belt 4 in the measuring instrument installation unit 11. The support roller 16 includes a carrier roller 16a and a return roller 16b. The carrier roller 16a is disposed in a range in which the belt 4 conveys a load, and supports the belt 4 in a range from the downstream end of the side skirt 23 to the pulley 13b. The measurement conveyor 5 shown in FIG. 2 has seven carrier rollers 16a arranged at intervals of 0.5 m to 1.0 m. The return roller 16 b is disposed in a range where the belt 4 returns with an empty load, and supports the belt 4 in a range from the pulley 13 b to the detour roller 17. The measurement conveyor 5 shown in FIG. 2 has three carrier rollers 16a.

  The bypass roller 17 includes a roller portion 17a that folds the belt 4 moved from the measured object discharge portion 3 downward, a roller portion 17b that folds the belt 4 folded downward in the second direction A2, and the belt 4 upward. And a roller portion 17d that folds the belt 4 moved upward in the second direction A2. That is, the height dimension of the measuring instrument installation unit 11 corresponding to the distance D1 substantially corresponds to the distance between the roller unit 17a and the roller unit 17b. Further, a pair of folding rollers 18 and a tension applying portion 19 are disposed between the roller portions 17b and 17c. The tension of the belt 4 is controlled by the tension applying unit 19.

  In the measurement of the radioactivity concentration, it is desirable to keep the shape of the measurement object M at the time of measurement in a predetermined shape such as a rectangular cross section. Therefore, as shown in FIG. 3, the radioactivity concentration measurement apparatus 1 includes a molding unit 21 that maintains the shape of the measurement object M in the measurement unit 8 in a substantially rectangular parallelepiped. The molding unit 21 molds a plurality of impact bars 22 that mold the bottom surface Ma of the measurement object M, a pair of side skirts 23 that mold the side surface Mb of the measurement object M, and an upper surface Mc of the measurement object M. And an adjustment plate 24. The impact bar 22 and the side skirt 23 cooperate to shape the shape of the measurement object M into a rectangular cross section. That is, the impact bar 22 and the side skirt 23 are installed in a range S in which the shape of the measurement object M needs to be maintained. The range in which the shape of the measurement object M needs to be maintained is a range including a location where the radioactivity concentration measuring device 12 is installed and a location where a laser rangefinder (shape acquisition unit) 28 described later is installed. is there.

  The impact bar 22 is a rod-shaped member, and a plurality of impact bars 22 are installed in the measurement object supply unit 2 and the measurement unit 8 so that the longitudinal direction thereof is along the first direction A1 (see FIG. 4). A plurality of impact bars 22 are also installed in the direction of the width D <b> 2 of the belt 4. Further, the impact bar 22 is installed so as to be in contact with the inner peripheral surface 4 b of the belt 4 in the carrier portion 6. The impact bar 22 is a resin rod-like member with little friction and good slidability, and the contact portion with the belt 4 is planar. Therefore, since the belt 4 on which the measurement object M is placed is supported in a planar shape, the bottom surface Ma of the measurement object M in contact with the belt 4 can be kept flat.

  The side skirts 23 are a pair of plate-like members disposed from the measured object supply unit 2 to the measurement unit 8 and are installed in the same range as the range where the impact bar 22 is installed. The pair of plate-like members that form the side skirts 23 are spaced apart from each other so as to form a width D3 that is smaller than the width D2 of the belt 4. Accordingly, the width D3 between the plate-like members corresponds to the width of the measurement object M. Further, the surface of the plate-like member that contacts the object to be measured M is orthogonal to the outer peripheral surface 4 a of the belt 4.

  The adjustment plate 24 is a plate-like member attached to the opening 91 a of the hopper 91. The adjusting plate 24 has the same width as the width D3 of the pair of plate-like members constituting the side skirt 23. Then, the belt 4 is fixed apart from the outer peripheral surface 4a of the belt 4 by a predetermined distance D4 such as about 200 mm. The measured object M passes through a gap formed between the outer peripheral surface 4a of the belt 4 and the lower end side 24a of the adjustment plate 24, so that the upper surface Mc of the measured object M is leveled. Therefore, the distance from the outer peripheral surface 4 a of the belt 4 to the lower end side 24 a of the adjustment plate 24 corresponds to the thickness MT of the measurement object M. Note that the thickness MT of the measurement object M can be changed by adjusting the mounting height of the adjustment plate 24.

  As shown in FIG. 4, the radioactivity concentration measuring apparatus 1 includes an activity concentration measuring instrument 12 for measuring the radioactivity concentration. The radioactivity concentration measuring instrument 12 includes a scintillator 12a that absorbs radiation energy and generates fluorescence, and a photoelectric conversion unit 12b that converts light generated by the scintillator 12a into an electrical signal. As the scintillator 12a, for example, a NaI (Tl) scintillator or a CsI (Tl) scintillator is used. A value (measurement detection value: CPS) obtained by counting the light generated by the scintillator 12a is output from such a radioactivity concentration measuring instrument 12.

  By the way, the radioactive concentration measuring instrument 12 has an incident surface 12c on which the radiation of the measurement object M is incident, and is installed so that the incident surface 12c faces the inner peripheral surface 4b side of the belt 4 in the measuring unit 8. Has been. Here, the inner peripheral surface 4b of the belt 4 is a back surface with respect to the outer peripheral surface 4a on which the measurement object M is placed. That is, the radioactivity concentration measuring instrument 12 is installed so as to face the back surface of the belt 4. A sliding plate 26 is sandwiched between the incident surface 12 c of the radioactivity concentration measuring device 12 and the belt 4, and the radioactivity concentration measuring device 12 is attached to the inner peripheral surface 4 b of the belt 4 via the sliding plate 26. In contact. The sliding plate 26 is fixed to the radioactive concentration measuring instrument 12. Therefore, the belt 4 moving in the first direction A1 slides with respect to the sliding plate 26. As the sliding plate 26, a resin plate having a thickness of about 10 mm so as not to shield radiation from the object M to be measured is used. Then, the incident surface 12c of the radioactivity concentration measuring instrument 12 is arranged at a position separated from the object to be measured M by the total length D5 of the thickness of the belt 4 and the thickness of the sliding plate 26. This total length D5 is 10 mm to 20 mm. In addition, this radioactive concentration measuring device 12 may be attached to the raising / lowering apparatus 27 (refer FIG. 2) which can move to an up-down direction.

  When measuring the radioactivity concentration, the output value may be indicated as the radioactivity concentration per unit mass. Further, if the radioactivity concentration differs between the two measurement objects even if the radioactivity concentration is the same, a difference may occur in the radioactivity concentration measured by the self-shielding effect. Therefore, as shown in FIG. 2, the radioactivity concentration measurement apparatus 1 includes various measuring instruments in order to obtain the weight and density of the measurement object M. The radioactivity concentration measuring apparatus 1 includes a laser rangefinder 28 as a shape acquisition unit that determines the shape of the measurement object M in the measurement unit 8 and a weight acquisition unit that obtains the weight of the measurement object M per unit length. Belt conveyor weight meter 29 and a non-contact type speed meter 31 as a speed acquisition unit for obtaining an actual moving speed of the belt 4. Furthermore, the radioactive concentration measuring device 1 includes a processing device 32 as a processing unit for processing these measured values. In the present invention, “the shape of the object to be measured” specifically refers to the three-dimensional shape of the object M to be measured. The “shape acquisition unit” for obtaining “the shape of the object to be measured” includes a laser rangefinder 28 as a shape acquisition unit and a non-contact type speedometer 31 as a speed acquisition unit.

  The laser rangefinder 28 is installed on the downstream side of the radioactivity concentration measuring instrument 12 in the measuring unit 8. The laser range finder 28 has a plurality of sensors arranged along the width direction of the object M to be measured. The shape of the upper surface Mc of the measurement object M is acquired. Here, as shown in FIG. 3, the cross-sectional shape of the measurement object M in the measurement unit 8 is formed in a rectangular shape by the impact bar 22, the side skirt 23, and the adjustment plate 24. The shape of the side surface Mb of the measurement object M is maintained by the side skirt 23, and the shape of the bottom surface Ma of the measurement object M is maintained by the belt 4 and the impact bar 22. On the other hand, after passing through the adjustment plate 24, the shape of the upper surface Mc of the measurement object M is not maintained like the side surface Mb and the bottom surface Ma. For this reason, the uneven state of the upper surface Mc is measured using the laser range finder 28 on the downstream side of the measuring unit 8 to obtain accurate cross-sectional shape data.

  As shown in FIG. 2, the belt conveyor weight meter 29 is installed in the transfer unit 9. The transfer unit 9 is provided on the downstream side of the measuring unit 8, specifically, on the downstream side of the range S in which the impact bar 22 and the side skirt 23 are formed. Moreover, it can be said that the transfer part 9 is the range where the carrier roller 16a is arrange | positioned. The belt conveyor weight meter 29 measures the weight per unit length of the measurement object M placed on the belt 4.

  The non-contact speedometer 31 is installed downstream of the belt conveyor weight meter 29 in the transfer unit 9. The non-contact speedometer 31 measures the actual transfer speed of the belt 4 or the object M placed on the belt 4. As the non-contact speedometer 31, a laser Doppler speedometer using the Doppler effect can be used. In addition to the non-contact speedometer 31, a contact speedometer or a rotational speedometer that detects roller rotation may be used for the speed acquisition unit.

  Each data acquired in the radioactivity concentration measuring device 12, the laser range finder 28, the belt conveyor weight meter 29, and the non-contact speedometer 31 is output to the processing device 32. In the processing device 32, various data processing is performed. For example, the count value output from the radioactivity concentration measuring device 12 is converted into the radioactivity concentration. This radioactivity concentration data is output to, for example, the damper chute 92 and used for the separation of the measured object M after measurement.

  Here, an example of calculating the radioactivity concentration will be described. In this calculation example, the radioactivity concentration is corrected using the density of the measurement object M. When the thickness MT of the object to be measured M (that is, the distance D4 between the belt 4 and the adjusting plate 24) is thin and the self-absorption effect of the radiation in the object to be measured M can be considered to be small, the light generated by the scintillator 12a is The relationship between the counted value (measurement detection value: CPS) and the radioactivity concentration (Bq) is determined by the shape of the measurement object M and the positional relationship with a measuring instrument such as the radioactivity concentration measuring instrument 12. If the self-absorption effect cannot be regarded as small (ie, the self-absorption effect cannot be ignored), the relationship between the measured detection value (CPS) and the radioactivity concentration per unit weight (Bq / kg) for each soil density It can be converted into a function and used for conversion. The radioactivity concentration (Bq / kg) per unit weight of the measurement object M is a value obtained by dividing the radioactivity concentration (Bq) by the weight.

When the relationship between the measured detection value (CPS) and the radioactivity concentration per unit weight (Bq / kg) can be defined by a linear equation as shown in Equation (1), the coefficient α is the density ρ of the object M to be measured. Inversely proportional to Therefore, a correction coefficient γ indicating the relationship between the coefficient α and the density ρ is determined in advance, and the radioactivity concentration Y ′ taking density correction into consideration is obtained using the equation (2).
Y (Bq / kg) = α × X (CPS) + β (1)
Y ′ (Bq / kg) = (γ / ρ) × X (CPS) + β (2)

ｖ：非接触式速度計３１によって計測される被計測物Ｍの移動速度（ｃｍ／秒）
ｎ：ベルト４の幅方向の分割数（即ちレーザ測距計２８が有するセンサの数）
ｄ：分割幅（ｃｍ）
ＭＴ：分割幅毎に計測された被計測物Ｍの厚み（ｃｍ） Here, the density ρ in the above equation (2) is calculated using the following equation (3).
ρ = (w / 60) / V (3)
w is the weight (w: kg / min) of the measurement object M output from the belt conveyor weigh scale (weight acquisition unit) 29. V is the volume (liter / second) of the object M to be measured. The volume V is calculated using the following formula (4).

v: Movement speed of the measurement object M measured by the non-contact speedometer 31 (cm / second)
n: Number of divisions in the width direction of the belt 4 (that is, the number of sensors included in the laser range finder 28)
d: Divided width (cm)
MT: Thickness (cm) of object M measured for each division width

For example,
v: 10 cm / sec n: 10
d: 5 cm
MT: 20cm
, The volume V is V = 10 × (10 × 5) × (20 + 20 +... +20) = 10 × 50 × 200 = 10000 cc / second = 10 liter / second.

  Next, an operation flow of the sorting device 90 including the radioactivity concentration measuring device 1 will be described. As shown in FIG. 5, first, earth and sand as the measurement object M are put into the hopper 91 (step S1). The introduced earth and sand passes through the hopper 91 and moves to the measurement object supply unit 2 in the measurement conveyor 5. When the measurement object M moves from the measurement object supply unit 2 in the first direction A1, it passes through the gap between the adjustment plate 24 of the hopper 91 and the belt 4, so that the thickness of the measurement object M is adjusted. (Step S2). Further, the measurement object M is moved to the area where the side skirt 23 is installed, and the side surface Mb is adjusted (step S3).

  And the to-be-measured object M in which the cross section was adjusted to the rectangular shape passes over the radioactive concentration measuring instrument 12 while passing through the measuring unit 8. At this time, the radioactivity concentration measuring instrument 12 captures the gamma rays emitted from the measurement object M and outputs a count value corresponding to the incidence of the gamma rays (step S4). When the measurement object M that has passed over the radioactivity concentration measuring instrument 12 passes under the laser rangefinder 28, the shape of the upper surface Mc is acquired (step S5). Subsequently, when the measurement object M passes over the belt conveyor weigh scale 29, the weight per unit length is acquired (step S6). Subsequently, the actual moving speed of the belt 4 is acquired when the belt 4 that transfers the measurement object M passes below the non-contact speedometer 31 (step S7). Then, the radioactivity concentration is calculated by the processing device 32 until the measurement object M passes below the non-contact type speedometer 31 and is transferred to the measurement object discharge unit 3 (step S8).

  The measurement object M discharged from the radioactivity concentration measuring device 1 includes a high-concentration measurement object M having a radioactivity concentration equal to or higher than the threshold value in the damper chute 92 based on the measured radioactivity concentration, and radiation below the threshold value. It is classified into a low-concentration object M having an effective concentration (step S9). The separated objects to be measured M are respectively transferred by the low concentration conveyor 94 or the high concentration conveyor 97 and stored in the low concentration container 93 or the high concentration container 96.

  Hereinafter, the operational effects of the radioactivity concentration measurement apparatus 1 will be described while comparing the radioactivity concentration measurement apparatus 1 according to the present embodiment with the radioactivity concentration measurement apparatus 100 according to the comparative example.

  As shown in part (a) of FIG. 7, a radioactivity concentration measuring apparatus 100 according to the comparative example includes a radioactivity concentration measuring device 101 and a belt conveyor 102 that transports an object M to be measured. As a configuration of the belt conveyor 102, a configuration in which a belt 104 is supported on a pair of pulleys 103 disposed at both ends and a plurality of rollers 106 are disposed between the belts 104 is often used. . Therefore, the interval E1 between the inner peripheral surfaces 104b of the belt 104 may be generally equal to or smaller than the diameter of the pulley 103. According to such a configuration, since the interval E1 between the inner peripheral surfaces 104b of the belt 104 and the interval E2 between the rollers 106 are small, the radioactive concentration measuring instrument 101 is disposed on the inner peripheral surface 104b side of the belt 4. It is difficult to secure enough space. Therefore, the radioactive concentration measuring instrument 101 is installed on the outer peripheral surface 104 a side of the belt 104. When the radioactivity concentration measuring instrument 101 is installed on the outer peripheral surface 104a side, a sufficient interval E3 of, for example, about 100 mm is provided so as not to contact the measurement object M placed on the belt 104. When the measurement object M adheres to the radioactivity concentration measuring instrument 101, the radioactivity concentration measurement instrument 101 measures the radioactivity concentration of the adhering substance in addition to the measurement object M to be transferred. This is because it becomes difficult to obtain.

  Further, the gamma ray GM from the measurement object M captured by the radioactivity concentration measuring instrument 101 attenuates in inverse proportion to the square of the distance. Therefore, the intensity of the gamma ray GM detected by the radioactivity concentration measuring instrument 101 decreases and the sensitivity decreases as the distance E3 between the measurement object M and the radioactivity concentration measuring instrument 101 increases. In addition, when an interval E3 is provided between the measurement object M and the radioactive concentration measuring instrument 101, gamma rays GB in the background environment may enter the radioactive concentration measuring instrument 101 from the interval E3. Therefore, as shown in part (b) of FIG. 6, when the intensity of the gamma ray GB in the background environment is high, in order to shield the gamma ray GB, the measurement object M and the radioactivity concentration measuring instrument 101 It is necessary to arrange a shield 107 that closes the interval E3. The shield 107 normally shields the six directions of the upper and lower surfaces and the side surfaces by using a thick plate such as lead, and also the upstream and downstream surfaces of the radioactivity concentration measuring instrument 12. In some cases.

  On the other hand, as shown in FIG. 6, in the radioactivity concentration measuring apparatus 1, the measurement object M is transferred in the first direction A <b> 1 in the carrier unit 6 of the measurement conveyor 5. And while this to-be-measured object M is transferred to the 1st direction A, the radioactive concentration is measured by the radioactive concentration meter 12. FIG.

  Here, the radioactivity concentration measuring instrument 12 is installed in a measuring instrument installation section 11 between the belt 4 in the carrier section 6 and the belt 4 in the return section 7. This measuring instrument installation part 11 is formed inside the belt 4 which is ring-shaped. That is, the radioactivity concentration measuring instrument 12 is installed on the inner peripheral surface 4b side of the belt 4 opposite to the outer peripheral surface 4a of the belt 4 on which the measurement object M is placed. Since the measurement object M is not placed on the inner peripheral surface 4 b of the belt 4, it is possible to install the radioactivity concentration measuring instrument 12 so as to be close to the measurement object M. That is, as shown in part (b) of FIG. 6, according to this installation, the total length D5 between the radioactivity concentration measuring instrument 12 and the object M to be measured is reduced, so that the radioactivity concentration measuring instrument The incidence of gamma rays GB in the background environment 12 is suppressed. Therefore, a decrease in the accuracy of the radioactivity concentration detected by the radioactivity concentration meter 12 is suppressed, and a reliable radioactivity concentration of the measurement object M can be continuously obtained.

  Further, according to the configuration in which the radioactivity concentration measuring device 12 is installed on the inner peripheral surface 4 b side of the belt 4, the measurement object M is covered above the radioactivity concentration measuring device 12. Then, since the measurement object M shields the gamma ray GB in the background environment, the measurement object M can be used as a self-shielding body. Therefore, since it is not necessary to install a shield above the radioactivity concentration measuring instrument 12, the configuration of the radioactivity concentration measurement apparatus 1 can be simplified and reduced in weight.

  A sliding plate 26 is installed between the radioactivity concentration measuring instrument 12 and the belt 4. According to this configuration, the radioactivity concentration measuring instrument 12 can be brought into contact with the belt 4 moving in the first direction A1 via the sliding plate 26. Therefore, the total length D5 between the measurement object M and the radioactivity concentration measuring instrument 12 can be set to about 10 mm to 20 mm, and the radioactivity concentration measurement accuracy can be improved. Further, since the radioactivity concentration measuring device 12 is in close contact with the belt 4 via the sliding plate 26, a shielding body is unnecessary in the vicinity of the radioactivity concentration measuring device 12, or a simple shielding body can be provided. it can. Therefore, the material for constituting the shield can be significantly reduced, and the weight and manufacturing cost of the radioactivity concentration measuring apparatus 1 can be suppressed.

  In addition, according to the configuration in which the total length D5 of the measurement object M and the radioactivity concentration measuring instrument 12 is small, the measurement range of the radioactivity concentration measuring instrument 12 is narrowed down, so that the measurement resolution can be improved.

  The radioactivity concentration measuring apparatus 1 further includes a laser range finder 28, a non-contact type speedometer 31, a belt conveyor weight meter 29, and a processing device 32 that obtains the radioactivity concentration of the measurement object M. ing. According to these configurations, since the density of the measurement object M can be obtained, the radioactivity concentration can be corrected using the density.

  In addition, according to the separation device 90 according to another embodiment of the present invention, since the radioactive concentration measuring device 1 can obtain a reliable radioactive concentration of the measurement object M, the measurement object M is reliably separated. Can do.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

  The moving speed of the belt 4 is not constant, and may be changed according to the purpose of measuring the radioactivity concentration. For example, when it is desired to improve the resolution and measurement sensitivity in the radioactivity concentration measuring instrument 12, the moving speed of the belt is set to a low speed. When it is desired to process high contaminants having a high radioactivity concentration at high speed, the belt moving speed is set to high speed.

DESCRIPTION OF SYMBOLS 1 ... Radioactivity concentration measuring device, 2 ... To-be-measured object supply part, 4 ... Belt, 5 ... Measurement conveyor (belt conveyor), 6 ... Carrier part, 7 ... Return part, 8 ... Measuring part, 9 ... Transfer part, 11 DESCRIPTION OF SYMBOLS ... Measuring device installation part, 12 ... Radioactivity concentration measuring device, 16 ... Support roller, 17 ... Detour roller, 22 ... Impact bar, 23 ... Side skirt, 24 ... Adjustment plate, 26 ... Sliding plate, 28 ... Laser distance measurement Meter (shape acquisition unit), 29 ... belt conveyor weight meter (weight acquisition unit), 31 ... non-contact type speedometer (speed acquisition unit), 32 ... processing device (processing unit), 90 ... sorting device, 91 ... hopper, 92 ... Damper chute (switching transfer unit), 93 ... Low concentration container (first object storage unit), 94 ... Low concentration conveyor, 96 ... High concentration container (second object storage unit) 97 ... Conveyor for high concentration, GB, GM ... Ga Ma line, M ... object to be measured.

Claims (4)

In the radioactivity concentration measuring device that measures the radioactivity concentration of the object to be measured that contains radioactive material and is transferred by the belt conveyor,
A carrier unit for moving the object to be measured in the first direction by moving a belt of the belt conveyor in the first direction;
A return portion in which the belt moves in a second direction opposite to the first direction;
A radioactivity concentration measuring instrument for obtaining a measurement detection value indicating the radioactivity concentration of the measurement object being transferred in the first direction,
The radioactivity concentration measuring device is a radioactivity concentration measuring device installed in a measuring instrument installation section between the belt in the carrier section and the belt in the return section. A sliding plate is installed between the radioactive concentration meter and the belt,
The radioactive concentration measuring device according to claim 1, wherein the sliding plate is fixed to the radioactive concentration measuring instrument and slides with respect to the belt. A shape acquisition unit for obtaining the shape of the measurement object;
A weight acquisition unit for obtaining the weight of the object to be measured;
A processing unit that obtains the radioactive concentration of the measurement object using the shape, the weight, and the measurement detection value,
The carrier unit has a measured object supply unit set on the upstream side, and a measured object discharge unit set on the downstream side,
The shape acquisition unit and the weight acquisition unit are installed between the measurement object supply unit and the measurement object discharge unit along the first direction, respectively. Radioactivity concentration measuring device. The radioactive concentration measuring apparatus according to any one of claims 1 to 3,
A first object storage unit for storing the object to be measured after the measurement;
A second object storage unit for storing the object to be measured after completion of measurement having a radioactivity concentration different from that of the object to be measured stored in the first object storage unit;
Using the radioactivity concentration acquired by the radioactivity concentration measurement device, the measurement object after the measurement is separated, and the first measurement object storage unit or the second measurement object storage unit. And a switching transfer unit for transferring to any of the above.

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