JP2005043272A - Body surface monitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase sensitivity for detecting radiation inside each foot in a body surface monitor. <P>SOLUTION: A wall section 100 is provided at a lower portion in a measuring room 18 and an under crotch type radiation detector is provided at the inside. A groove S9R for the right foot is formed at both the sides of the wall section 100 and a groove 102L for the left foot is formed at the other side. Radiation from the inside of each foot is detected by the under crotch type radiation detector, thus increasing the detection sensitivity. It is preferable that a double-sided radiation detector is used as such a detector. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a body surface monitor that measures radiation from a measurement subject.

  The body surface monitor functions as a body surface radiation measurement device, and is installed in, for example, a nuclear power plant or a nuclear fuel processing facility. That is, a body surface monitor is installed at the entrance and exit of the radiation management area, and radiation is measured for the exposure management of workers entering the radiation management area and workers leaving the radiation management area.

  A conventional body surface monitor is generally composed of a main body, an entrance door, an exit door, and the like. Conventionally, when the entrance door is open and the exit door is closed, the worker enters the measurement chamber, the worker turns 90 degrees in the measurement chamber, and the right hand and the left hand are formed on the front. Insert your hand into the measuring unit. In this state, the entrance door is closed, and radiation is measured over a predetermined time. After completion of the measurement, the exit door is opened and the worker leaves the measurement chamber. Then, the exit door is closed and the entrance door is opened. This process is repeated for each worker. Patent Document 1 listed below discloses a body surface monitor that can perform measurement without changing the orientation in a measurement chamber.

  In the body surface monitor, in order to detect radiation from the measurement subject with high sensitivity, there is a demand to place the radiation detector as close to the measurement subject as possible. Therefore, a body surface monitor that is provided with a head detector that moves up and down and can adjust the height of the head detector according to the height of the subject has also been put into practical use (for example, Patent Document 2 and Patent Document 3). ). In addition, there is Japanese Patent Application No. 2002-15961 as an unpublished patent application related to the present application.

Japanese Patent No. 2807168 Japanese Utility Model Publication No. 63-129848 JP-A-4-310892

  In the conventional body surface monitor, the radiation detector directly facing the outside and the back side of each foot is provided, but the radiation detector corresponding to the inside of each foot is not provided. Therefore, sufficient detection sensitivity cannot always be obtained for the inside of the foot. In particular, from the vicinity of the heel to the lower part (the lower part of both feet), depending on the work environment, contamination by radioactive materials may occur.

  An object of the present invention is to increase the detection sensitivity of radiation on the inside of each foot.

(1) The present invention is a main body having a measurement chamber for accommodating a person to be measured, and a plurality of radiation detectors for detecting radiation from the person to be measured accommodated in the measurement chamber, wherein the crotch type radiation stands upright And a radiation detector group having a detector.

  According to the above configuration, since the crotch type radiation detector is included in the radiation detector group, the detection sensitivity for the radiation from the inside of the foot can be increased.

  Preferably, the crotch type radiation detector is configured as a double-sided radiation detector. If the crotch type radiation detector is configured as a double-sided radiation detector, its thickness can be reduced and it does not get in the way.

  Preferably, the crotch type radiation detector has a form extending from the entrance side to the exit side of the measurement chamber, and on the both sides of the crotch type radiation detector in the lower part of the measurement chamber, the entrance side of the measurement chamber A right foot groove and a left foot groove penetrating from the base to the exit side are formed. According to this configuration, radiation is measured without entering the entrance side and changing the direction.

  As described above, according to the present invention, the radiation detection sensitivity can be increased on the inside of each foot.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.
FIG. 1 shows a preferred embodiment of a body surface monitor according to the present invention, and FIG. 1 is a perspective view of the body surface monitor viewed from the entrance side.

  The body surface monitor shown in FIG. 1 is installed at, for example, a nuclear power plant. Specifically, the body surface monitor is provided at the entrance and exit of a radiation control area, and body surface contamination is measured for workers entering and leaving the radiation control area. It is a device to do. The facility where the body surface monitor is installed is provided with a pressurized air outlet (not shown) at a required location, from which the pressurized air is introduced into the body surface monitor and an air cylinder or the like. Is driven.

  The body surface monitor is roughly divided into a main body 10, an entrance door 12, an exit door 14, a base 16 and a ceiling portion 17. The main body 10 has a measurement chamber 18 as a cavity formed from the inlet opening to the outlet opening. In FIG. 1, the Y direction is the direction in which the worker advances, the X direction is the left-right direction with respect to the worker, and the Z direction is the height direction.

  The measurement chamber 18 as a cavity is roughly divided into three parts. That is, it is divided into an upper part, a middle part and a lower part. As shown in FIG. 1 and FIG. 3 to be described later, the middle part is wide in the X direction, the upper part is gradually narrowed in the X direction toward the upper part, and the lower part is narrowed in the X direction toward the lower part. The width of is gradually narrowing. Therefore, the measurement chamber 18 has a substantially vertically long rhombus shape as viewed from the entrance side. This rhombus shape is a shape corresponding to various heights and body shapes of an approximately assumed worker, and is a form in which a radiation detector described later can be brought close to the body surface as much as possible.

  In the measurement chamber 18, a pair of hand detection units 26 are provided at the left and right ends in the X direction in the intermediate portion. The hand detection unit 26 has a groove 28 as a vertical groove or a V-shaped groove communicating with the measurement chamber 18. This groove 28 is a groove penetrating in the Y direction. The right hand or the left hand is inserted into the groove 28, and in this state, the radiation of the inner and outer surfaces of the hand is measured. A partition wall 30 is formed between the groove 28 and an intermediate portion of the measurement chamber 18, and radiation detectors S6 and S12 are provided in the partition wall 30 (see FIG. 3). Radiation detectors S8 and S14 are provided on the inner surface of the groove 28 facing the radiation detectors S6 and S12 (see FIG. 3). These radiation detectors and other radiation detectors are planar radiation detectors, and specifically include a scintillator plate and a plurality of photomultiplier tubes. The radiation detector group includes a plurality of tilting radiation detectors and a plurality of double-sided radiation detectors.

  The main body 10 is formed with two upper inner surfaces 22 and two lower inner surfaces 24 as inclined surfaces facing the measurement chamber 18. The upper inner surface 22 is inclined toward the measurement chamber 18 at a constant angle, and the lower inner surface 24 is also inclined upward while opening upward.

  Therefore, as described above, the measurement chamber 18 has a vertically long rhombus shape as a whole. The measurement chamber 18 further has a ceiling surface and a floor surface, and a radiation detector S9 for measuring radioactive contamination of the foot is provided on the floor surface. At the time of measurement, the operator stands up on the floor surface, and the radiation is measured with both hands inserted into the respective hand detection units 26.

  In the present embodiment, a wall portion 100 standing on the base 16 is provided, and a radiation detector (inseam radiation detector) S18 is provided therein (see FIG. 3). Such a radiation detector S18 is configured as a double-sided radiation detector and detects radiation from the inside of the lower part of the foot (for example, a range from the floor level to the shin level). A foot groove 102R for the right foot and a foot groove 102L for the left foot are formed as through grooves on both sides in the X direction of the wall portion 100, and the right foot and the left foot are inserted into each foot groove 102R, 102L.

  Further explaining the radiation detector, the entrance door 12 is provided with three radiation detectors S1 to S3 from the upper side to the lower side in the present embodiment. Further, two radiation detectors S4, S10 and S5, S11 are provided on the two upper inner surfaces 22 side by side (see FIG. 3). In addition, two radiation detectors S6, S12 and S7, S13 are provided on the two lower inner surfaces 24 side by side (see FIG. 3). The exit door 14 is provided with three radiation detectors from the top to the bottom in the present embodiment, but is not shown. Radiation detectors S9R and S9L are provided on the floor surface on the left and right of the wall portion 100 (on the bottoms of the foot grooves 102R and 102L). They mainly detect radiation from the back of each foot.

  Of course, the arrangement of each radiation detector is merely an example, and various arrangement methods can be used. However, it is desirable to arrange each radiation detector so that body surface contamination can be measured over the entire body of the operator who is the subject.

  In the above, the radiation detectors S4, S5, S10, and S11 are tilting radiation detectors, and the radiation detectors S6 and S12 are double-sided detectors. Their configuration will be described in detail later.

  The ceiling portion 17 is provided with a display 17A for displaying the measurement status, and the liquid crystal display 51 for displaying an instruction to the next person to be measured is provided on the entrance side. In addition, although the same liquid crystal display is provided in the exit side, it is utilized when using an exit side as an entrance side for convenience.

  The entrance door 12 is attached to the shaft 12A and is rotatable, and similarly, the exit door 14 is attached to the shaft 14A and is rotatable. They are driven by pressurized air introduced as described above. The plurality of tilting radiation detectors are also driven by pressurized air. However, it may be replaced by an electric drive system or may be used in combination. A member 12B provided between the shaft 12A and the entrance door 12 is provided with an auxiliary liquid crystal display 12C. Similarly, an auxiliary liquid crystal display (see FIG. 2) is also provided on a member provided between the shaft 14A and the exit door 14. On these liquid crystal displays, guidance and the like are displayed to the subject during measurement.

  A transmissive or reflective optical height sensor 52 is provided on the entrance side of the measurement chamber 18. The height sensor 52 is constituted by a large number of optical elements arranged in the vertical direction, and the height or height classification of the subject is measured. The measurement is preferably performed when the person to be measured enters, but the height may be measured at the stage of being accommodated in the measurement chamber 18. The height sensor 52 shown in FIG. 1 is an example, and other sensors such as an ultrasonic sensor can be used. Based on the height measured by the height sensor 52, a control unit (not shown) controls the tilting motion (falling motion, rising motion) of the plurality of tilting radiation measuring instruments.

  A sensor 54 provided facing each groove 28 is an optical sensor that detects that a hand has been inserted into the groove 28. A sensor 53 provided on the lower inner surface 24 is an optical sensor for detecting the presence of a person to be measured in the measurement chamber. Each sensor 53, 54 is a reflective or transmissive sensor. The controller determines the presence and proper posture of the person to be measured based on the outputs of the sensors 53 and 54, and controls the operation of the body surface monitor based on the judgment. The mat sensor 50 is provided at a waiting place for the next person to be measured, and detects that the next person to be measured is standing there. The detection result is also sent to the control unit. Further, a load sensor may be disposed on the base 16.

  FIG. 2 is a perspective view showing the outlet side of the body surface monitor. Reference numeral 55 denotes a box in which an electronic circuit including a control unit is accommodated. The entrance door 12 and the exit door 14 have a vertically long rectangle, while the measurement chamber has a vertically long rhombus. Even when both doors are closed, a plurality of substantially triangular shapes in which the measurement chamber and the outside communicate with each other. A gap is formed, and the presence of such a gap gives a sense of security to the measurement subject accommodated in the measurement chamber 18.

  As shown in FIGS. 1 and 2, in the above configuration, the shaft 12 </ b> A of the entrance door 12 is set on the right side when viewed from the entry direction, but of course it may be on the left side. Similarly, the shaft 14A of the outlet door 14 is formed on the right side when viewed from the outlet side to the inlet side, but of course it may be on the left side. Alternatively, the entrance door 12 and the exit door 14 may be double doors that open from the center in the left-right direction.

  In FIG. 1, in this embodiment, the height of the vertex of the partition wall 30 is set within a range of 90 to 100 cm, for example, and preferably 95 cm from the floor surface. The distance between the centers of the two grooves 28 is, for example, 60 to 120 cm, and desirably 90 cm. Further, the depth of the groove 28 is, for example, 30 to 45 cm, and preferably 40 cm. The height of the wall portion 100 or the crotch type radiation detector S18 is, for example, 5 to 50 cm, and preferably 35 cm. The width in the X direction is, for example, 2 to 5 cm, and desirably 3 cm. Furthermore, although the height from the floor surface to the ceiling surface is 2 m, for example, other values may be adopted. The angle of inclination of the upper inner surface 22 from the vertical is, for example, 0 to 80 °, and preferably 35 °. The open inclination angle of the lower inner surface 24 is, for example, 0 to 20 °, and preferably 10 °. However, each of the numerical values given above is an example, and other values can be adopted. For example, all or part of the lower inner surface 24 may be a vertical surface. Also, the upper inner surface 22 can be entirely or partly vertical, and the inclination angle can be set in two or more steps. Ultimately, the measurement chamber 18 can be configured as a vertically long ellipse. However, according to the embodiment of the present embodiment, since it has a relatively simple form and can perform efficient measurement, it has practical value.

  Next, the operation of the body surface monitor (control contents of the control unit) will be described. First, in a state where the exit door 14 is closed, an operator (a person to be measured) enters the measurement chamber 18 from the entrance opening side and stands on the floor surface. At that time, the height of the worker is measured by the height sensor 52, and the presence of the worker is detected by the sensor 53. In the standing state, the operator faces the inner surface of the exit door 14. In this state, both hands are inserted into the two hand detection units 26. Each foot is properly positioned in each groove 102R, 102L. The state is detected by the sensor 54. Prior to the start of measurement, the entrance door 12 is closed. Simultaneously with such a process (or before or after closing the entrance door 12), in order to increase the detection sensitivity of the upper part of the head etc. according to the height of the operator, among the four tilting radiation detectors One or more of these fall down. The tilt angle depends on the height of the worker, and in any case, the tilted radiation detector is at such an angle that the sensitive surface of the radiation detector can be brought close to the worker without touching the worker. The posture is adjusted. Radiation measurement is performed for a predetermined time from the time when the entrance door 12 is closed or the time when the necessary operation is completed.

  When the radiation measurement is completed, only the exit door 14 is opened, which allows the operator to exit forward. Before or simultaneously with the opening operation of the exit door 14, one or more tilting radiation detectors that are in a fallen state return to the original state. However, if the height data of the next worker can be obtained in advance, it may be adjusted to an inclination angle corresponding to the height of the worker in order to shorten the operation time. After the worker exits, the exit door 14 is closed and the entrance door 12 is opened, and the same process is repeated.

  Therefore, the operator as the person to be measured does not need to change the direction inside the measurement chamber 18, so that the measurement time per person can be shortened. Moreover, since the radiation detector is brought close to the body surface particularly in the upper and lower parts of the operator, the detection sensitivity can be increased. Further, the measurement chamber 18 shown in FIG. 1 has a rhombus shape, and the measurement chamber 18 is configured to have a certain height, so that radiation measurement is performed by accommodating almost all workers. It is possible.

  In the body surface monitor of the present embodiment, hand part detection units 26 are fixedly provided at both left and right ends of the measurement chamber 18. However, the length of the hand is generally proportional to the height, and no particular problem arises even with such a fixed arrangement. Moreover, in general, in the case of a tall person, two hands can be inserted into the hand detection unit 26 without opening the two upper arms so much, while in the case of a short person Since the two upper arms are opened to some extent and the two hands are inserted into the hand detection unit 26, the difference in arm length and the height difference are caused by such differences in the upper arm opening or the bending angle of the joint. Can be absorbed or adjusted. For this reason, even if the hand part detection unit 26 is fixedly arranged, radiation measurement on both hands can be performed reliably according to various heights. However, the hand part detection unit 26 may be movable in the vertical direction as necessary.

  FIG. 3 schematically shows the arrangement of radiation detectors in the body surface monitor. On the right side from the entrance side, radiation detectors S4, S5, S6, S8, and S7 are provided from the top to the bottom. On the left side from the entrance side, radiation detectors S10 and S11 are provided from the top to the bottom. , S12, S14, and S13. Further, radiation detectors S9R and S9L are provided on the floor surface. Further, a radiation detector S18 as a double-sided radiation detector is provided in the wall portion 100. If two independent radiation detectors are provided in the wall portion 100, the thickness of the wall portion 100 becomes unnecessarily thick or the arrangement itself becomes difficult. According to the present embodiment, however, By using such a double-sided detection type radiation detector, highly sensitive radiation detection can be performed on the inside of the foot while making the wall portion 100 thin.

  The radiation detectors S6 and S12 are double-sided radiation detectors provided on the partition wall 30, and both of the radiation from the torso or waist of the subject and the radiation from the inside of the arm. taking measurement.

  In the configuration example shown in FIG. 3, the radiation detectors S4, S5, S10, and S11 are tilting radiation detectors. Reference numerals S4 ', S5', S10 ', and S11' each indicate a state of being collapsed with the lower end side as the rotation center. Either the upper radiation detectors S4 and S10 or the lower radiation detectors S5 and S11 are tilted according to the height of the measurement subject. However, such a tilting operation does not have to be performed when the height of the person being measured is quite high. Further, the upper radiation detectors S4 and S10 may be tilted and the lower radiation detectors S5 and S10 may be tilted. That is, it is desirable to adjust the inclination angle of each radiation detector so that each radiation detector comes close to the head and shoulders of the subject according to the height of the subject.

  Further, as indicated by reference numeral S4 ″, if only one of the opposed radiation detectors S4 and S10 is greatly tilted and moved, the person with a short height is the same as the ceiling type radiation detector. Measurement on the upper side can be performed. Even in this case, if the pair of radiation detectors S5 and S11 in the lower stage are also tilted, they can be brought closer to the body surface to improve detection sensitivity.

  The large falling movement as described above is performed when the height of the person to be measured is equal to or less than a certain height. As the certain height, the pair of radiation detectors S4 and S10 physically interfere (collision) when they fall. It is set as the height corresponding to the angle immediately before the end. In the case where only one such tilting motion is performed, the pair of radiation detectors S4 and S10 may be selectively performed (preferably alternately) in a predetermined order. If it does in that way, the load added to each mechanism part can be equalized.

  As described above, since a plurality of posture variable radiation detectors are provided on the left and right and top and bottom, high sensitivity measurement can be performed by bringing each radiation detector close to the body surface according to the height or body shape of the subject. .

  FIG. 4 shows a cross-sectional view of a configuration example of the double-side radiation detector. The inside of the case 120 is hollow, and substrates 124A and 124B made of transparent acrylic or the like are provided on one surface and the other surface thereof. The scintillator plates 126A and 126B made of plastic scintillators and the like are superposed on them, and they are further covered with aluminized mylar films 128A and 128B. The case 120 is provided with a pair of photomultiplier tubes 130 (only one photomultiplier tube is shown in the figure). Due to the incidence of radiation, light is emitted from the scintillator plates 126A and 126B, and the light passes through the substrates 124A and 124B and is emitted into the case 120. When the light reaches the light receiving surface of the photomultiplier tube 130, it is detected as an electrical signal. The output signals of the pair of photomultiplier tubes are input to a known coincidence circuit or the like.

  According to the body surface monitor of the present embodiment, since the crotch type radiation detector is provided, the radiation detection sensitivity can be increased on the inside of each foot. Since the lower part of each foot is surrounded by the radiation detector as a whole, highly sensitive detection can be performed for that part. Therefore, highly reliable measurement can be realized.

  The height of the crotch type radiation detector can be set to a desired value according to the height range of the person to be measured. In the above embodiment, the crotch type radiation detector is fixedly disposed. However, the elevating mechanism is provided on the crotch type radiation detector, and from the time when the person to be measured positions both feet in an appropriate position (preferably, it is detected by a sensor), the inseam The type radiation detector may be raised and set to a normal height, and the crotch type radiation detector may be lowered to the floor level after the measurement is completed. According to this configuration, there is an advantage that the crotch type radiation detector does not get in the way when entering and leaving the measurement chamber. In that case, the protrusion height of the crotch type radiation detector may be adaptively controlled according to the height of the person to be measured or the length of the crotch.

It is the perspective view which looked at the body surface monitor concerning the present invention from the entrance side. It is the perspective view which looked at the body surface monitor which concerns on this invention from the exit side. It is explanatory drawing for demonstrating arrangement | positioning of a some radiation detector. It is sectional drawing which shows the structural example of a double-sided radiation detector.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Main body, 12 Entrance door, 14 Exit door, 16 Base, 17 Ceiling part, 26 Hand part detection unit, 100 Wall part, S4, S5, S10, S11 Tilt type radiation detector, S18 Inseam type radiation detector.

Claims (3)

A main body having a measurement chamber for accommodating a person to be measured;
A plurality of radiation detectors for detecting radiation from the measurement subject accommodated in the measurement chamber, the radiation detector group having a standing crotch type radiation detector;
A body surface monitor comprising: The body surface monitor according to claim 1,
The crotch type radiation detector is configured as a double-sided radiation detector. The body surface monitor according to claim 1,
The crotch type radiation detector has a form extending from the entrance side to the exit side of the measurement chamber,
A body surface monitor comprising a right foot groove and a left foot groove penetrating from the entrance side to the exit side of the measurement chamber on both sides of the crotch type radiation detector in the lower part of the measurement chamber.

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