Mobile carrier intended for a measuring device

Abstract

Mobile carrier (1), intended to support a radiation detector (30), the carrier comprising: a chassis (5), movable on wheels (6), the wheels defining a rolling plane (PXY) of the carrier; a plate (10), extending perpendicularly to the rolling plane, the plate being fixed relative to the chassis (5), the plate being connected to a trolley (20), arranged to receive the detector, the plate being arranged so that the trolley is movable in translation relative to the plate, along an axis of translation (Z) perpendicular to the rolling plane, the height of the trolley relative to the rolling plane being continuously adjustable; the trolley being movable in rotation relative to the plate, along an axis of rotation (Δ) parallel to the rolling plane.

Description

Title of the invention: Mobile carrier intended for a measuring device Technical field

[0001] The technical field of the invention is the radiological characterization of structures or equipment of a nuclear installation. PREVIOUS ART

[0002] During the operation of a nuclear facility, the structures, civil engineering or equipment of the facility may be contaminated by radionuclides. During dismantling operations, it is useful to estimate the residual activity levels in the facility. This makes it possible to establish scenarios for the work to be carried out, as well as to predict the quantity of nuclear waste that will be generated. For this purpose, it is useful to carry out in-situ measurement campaigns, during which an ionizing radiation detector is deployed in the field.

[0003] When it comes to detecting gamma radiation, a radiation detector can be relatively heavy, usually exceeding a few kg. This high weight is due to the use of shielding, arranged around the detector and intended to delimit the field of observation of the detector. However, the position of the detector, relative to an object to be controlled, must be controlled. It is therefore useful to have a carrier, allowing easy movement of the detector in installations likely to be cluttered or cramped. Furthermore, the carrier must allow the detector to be held in different positions or orientations relative to the object to be controlled, while being simple to handle.

[0004] One intended application concerns the control of concrete walls, forming the civil engineering of nuclear installations. During dismantling operations, the radiological state of the civil engineering must be controlled before said operations, in order to carry out the radiological inventory, but also after the operations, in order to control the residual activity. For this type of operation, the use of gamma spectrometry detectors is common. However, this requires a carrier that can be moved in construction site environments.

[0005] The company Mirion, specialized in the field of nuclear measurements, markets a mobile carrier for moving and maintaining a spectrometry measuring device. This carrier is well suited to field measurements. It allows a gamma spectrometer, protected by shielding, to be placed in different positions.

[0006] However, the inventors found that the number of positions defined in Using the carrier is too limited. In addition, two adjacent positions are too far apart. They propose an improved carrier, allowing greater variability in detector positions. In addition, the carrier allows the position or orientation of a detector to be easily changed. The objective is to more precisely and easily adjust the position of the detector relative to an object to be controlled. Statement of the invention

[0007] A first object of the invention is a mobile carrier, intended to support a radiation detector, the carrier comprising: - a chassis, mobile on wheels, the wheels defining a rolling plane of the carrier; - a plate, extending perpendicular to the rolling plane, the plate being fixed relative to the chassis, the plate being connected to a carriage, arranged to receive the detector, the plate being arranged so that the carriage is movable in translation relative to the plate, along a translation axis perpendicular to the rolling plane, the height of the carriage relative to the rolling plane being continuously adjustable; - the carriage being movable in rotation relative to the plate, around an axis of rotation parallel to the rolling plane; - so that the position of the carriage can vary, relative to the rolling plane, in rotation, along the axis of rotation, and in translation, along the axis of translation.

[0008] The carrier thus defined makes it possible to maintain the detector, on the carriage, at a multitude of heights relative to the rolling plane, along the translation axis, and at a multitude of angular positions around the rotation axis.

[0009] By continuously adjustable, we mean that two successive positions are offset by a small step, typically less than 1 cm or 2 cm.

[0010] According to one possibility, the carriage is connected to the plate by a worm screw, extending parallel to the translation axis, so that a rotation of the worm screw causes the translation of the carriage. The worm screw can be manually actuated.

[0011] According to one possibility, the carriage is continuously orientable according to a plurality of rotation angles around the rotation axis. By continuously orientable, it is meant that two successive positions are offset by a small angular step, typically less than 5° or 3°.

[0012] According to one possibility, the carrier comprises a control unit, intended to be connected to the detector, the control unit being configured to generate a reference signal for the position of the detector as a function of a detection signal resulting from the detector.

[0013] The carrier may comprise at least one location unit, configured to establish a distance between the carrier and a reference object, the distance being determined parallel to the rolling plane.

[0014] The location unit may comprise at least one rangefinder.

[0015] The carrier may comprise a three-dimensional camera, secured to the carrier, and configured to acquire three-dimensional geometric data in an observation field of the radiation detector.

[0016] Another object of the invention is a method of arranging a detector using a carrier according to the first object of the invention, the method comprising: a. arranging the detector on the carriage; b. taking into account a height, along the translation axis, and an orientation of the detector, around the rotation axis, relative to an object to be controlled; c. control of the translation and rotation of the carriage to reach the predetermined height and orientation.

[0017] The invention will be better understood upon reading the description of the exemplary embodiments presented in the remainder of the description, in conjunction with the figures listed below. FIGURES

[0018] [Fig.l] [Fig.l] shows a three-dimensional view of a carrier according to the invention. In each of the figures, the Z axis is considered to be vertical.

[0019] [Fig.2A] [Fig.2A] represents a front view of the wearer, in a vertical plane.

[0020] [Fig.2B] [Fig.2B] shows a front view of the carrier plate.

[0021] [Fig.3] [Fig.3] shows a side view of the carrier, in a vertical plane.

[0022] [Fig.4] [Fig.4] is a view detailing the carrier's carriage.

[0023] [Fig.5] [Fig.5] shows a schematic view of the carrier from above.

[0024] [Fig.ôA] [Fig.ôA] shows a configuration in which the carriage is in a low position.

[0025] [Fig.ôB] [Fig.ôB] shows a configuration in which the carriage is in the high position. PRESENTATION OF SPECIAL EMBODIMENTS

[0026] Figures 1, 2A, 2B and 3 represent a three-dimensional view of an example of a carrier 1 according to the invention. The carrier 1 comprises a chassis 5 mounted on wheels 6. The chassis is configured to be easily movable along a rolling plane Pxy defined by the wheels 6. The rolling plane PXy extends parallel to a lateral axis X and a longitudinal axis Y.

[0027] The carrier is intended to support a radiation detector 30. In this example, the radiation detector 30 is a Germanium type gamma spectrometry detector. The detector comprises a detection crystal 31 connected to a cryostat 32. The connection between the radiation detector 30 and the carrier 1 is provided by a carriage 20. The carriage comprises a means for fixing the detector. The detector comprises a frame 23, the latter being fixed to the carriage, for example using clamping lugs or screws. The carriage 20 is movable in translation, relative to the chassis 5, along a translation axis Z perpendicular to the rolling plane PXY.

[0028] The carriage 20 is held by a plate 10, the latter being integral with the chassis. The plate 10 comprises a translation mechanism, manually controllable, allowing a translation of the carriage 20 along the translation axis Z. In this example, the translation mechanism comprises a worm screw 12 controlled by a crank 11. Conventionally, under the action of a rotation of the worm screw 12, the carriage 20 moves in translation along the plate 10. Guide rails 13 are provided on the plate, allowing the translation of the carriage 20.

[0029] The actuation of the translation mechanism allows precise control of the translation along a translation distance. The translation distance can be between 50 cm and 2 m. Along the translation distance, the carriage can occupy a large number of different positions. The resolution of the translation mechanism allows two successive positions to be spaced less than 2 cm, or even less than 1 cm, or even less than a few millimeters. Thus, the position of the carriage, along the translation axis, can be precisely adjusted. This allows a "continuous" translation of the carriage, in the sense that the difference between two successive positions, along the translation axis, is small: less than 2 cm or less than 1 cm.

[0030] A linear graduation can be arranged on the plate 10, parallel to the translation axis Z, this graduation being coupled to a mechanical reference mark secured to the carriage 20. This allows quantification of the position of the carriage 20 along the Z axis.

[0031] The carriage 20 is rotatable about an axis of rotation A parallel to the rolling plane PXY. The rotation of the carriage 20 makes it possible to orient the latter in an angular range of 180°, or even 360°. Thus, the carriage comprises a rotation mechanism, making it possible to adjust the rotation of the carriage about the axis of rotation A.

[0032] In this example, the rotation mechanism comprises a worm screw 22 controlled by a crank 21. The worm screw 22 is shown in [Fig.4]. Under the action of a rotation of the worm screw 22, the carriage moves in rotation around the axis of rotation A. The actuation of the rotation mechanism allows precise control of the translation along a translation distance. The translation distance can be between 20 cm and 2 m. Around the axis of rotation A, the carriage 20 can occupy a large number of different angular positions. The resolution of the rotation mechanism makes it possible to space two successive angular positions by less than 5°, or even less than 3°, or even of the order of a degree. This allows a “continuous” rotation of the carriage, in the sense that the angular difference between two positions successive is weak.

[0033] An angular graduation 23 can be arranged on the carriage 20, around the axis of rotation A, this graduation being coupled to a mechanical reference mark secured to the plate 10. This allows quantification of the angular position of the carriage 20, around the axis of rotation A.

[0034] The connection between the plate 10 and the carriage 20 is ensured by an interface part 24, visible in [Fig. 4], which allows reversible fixing of the carriage on the plate. The carriage is configured to hold the detector 30. In [Fig. 3], the carriage is shown, holding the detector 30 in a horizontal position, in two different positions, along the translation axis Z.

[0035] Alternatively, the translation and / or rotation mechanisms are motorized. According to one possibility, the translation and / or rotation of the carriage are controlled by a control unit 40. Position sensors may be arranged on the carriage, so that a position signal is addressed to the control unit. The position signal includes information on the translational and rotational position of the carriage 20.

[0036] The detector 30 may be connected to a processing unit 35, intended to collect the data measured by the detector and to establish an interpretation. The processing unit 35 may in particular comprise a computer, programmed to give an interpretation result of the measurements resulting from the detector 30. According to one possibility, depending on the measurements resulting from the detector 30, the processing unit 35 establishes a setpoint signal, addressed to the control unit 40. The setpoint signal is configured to control a rotation and / or a translation of the carriage 20.

[0037] In order to assign a location to each measurement, the carrier may comprise a location unit 7. The location unit is arranged on the carrier 1, and makes it possible to establish a location of the carrier in the environment. Since the carrier is essentially intended for indoor use, the use of a GPS beacon is not recommended. The location unit is preferably autonomous, in the sense that it does not use an external communication network. The location unit may be formed by two laser rangefinders, making it possible to establish a position of the carriage or the carrier parallel to the rolling plane. The two rangefinders are oriented at 90° to each other. They are intended to establish a distance between the carrier 1 and a reference wall.

[0038] In [Fig. 5], two rangefinders 7X, 7Y are shown forming a location unit 7 making it possible to establish a distance from the carriage 20 respectively along the X axis (distance dx) and along the Y axis (distance dY). This makes it possible to obtain a position of the carriage 20 along the longitudinal axis X and along the lateral axis Y. In [Fig. 5], a reference wall ref x and a reference wall refY are shown respectively parallel to the X axis and to the Y axis.

[0039] In [Fig.5], the detector is oriented so that the crystal 31 points towards the rolling plane. Such a configuration is shown in [Fig.6A]. According to this configuration, the crystal is located at a distance of 96 mm from the rolling plane PXY. This corresponds to a low position of the carriage 20. [Fig.6B] shows an opposite configuration, according to which the crystal points upwards, the carriage 20 being in the high position.

[0040] According to this embodiment, depending on the signal resulting from the detector 30 and processed by the processing unit 35, the height of the detector relative to the rolling plane can be defined by the control unit 40.

[0041] The carrier 1 may have, along the translation axis Z, a height which may be between 1 m and 2 m. Along the X axis and the Y axis, the dimension of the carrier is preferably less than 1 m or 1.5 m.

[0042] The configurations shown in Figures 2A, 6A and 6B are suitable for the radiological control of walls, whether vertical walls ([Fig.2A]), floors ([Fig.6A]) or ceilings ([Fig.6B]). The configuration of [Fig.6B] also makes it possible to carry out a measurement according to a so-called “Marinelli” geometry, according to which a sample is arranged around the detector. The coupling with the location unit 7 provides assistance in positioning the carriage in the controlled installation.

[0043] According to one possibility, the carriage comprises a 3D visualization means, for example a three-dimensional camera. This makes it possible to obtain three-dimensional geometric data in the field of observation of the detector. Geometric data of a component, present in the field of observation, that it is desired to characterize, are thus obtained, and this simultaneously with the acquisition of radiological data by the radiation detector. The component can be any equipment, for example a wall, but also a tank or a pipe or any other process equipment. The three-dimensional geometric data can be for example: - dimensions of the observed component; - relative positioning and / or orientation data of the detector in relation to the component.

[0044] The three-dimensional geometric data can be combined with the radiological data resulting from the detector. The combination of the geometric data and the radiological data allows a quantitative interpretation of the radiological activity of the measured component.

[0045] The invention may be implemented for the control of structures or equipment of nuclear installations, in support of maintenance or dismantling operations. It may also be deployed for carrying out radiological control on contaminated land.

Claims

Claims

1. Mobile carrier (1), intended to support an ionizing radiation detector (30), the carrier comprising: - a chassis (5), movable on wheels (6), the wheels defining a rolling plane (PXy) of the carrier; - a plate (10), extending perpendicular to the rolling plane, the plate being fixed relative to the chassis (5), the plate being connected to a carriage (20), arranged to receive the detector, the plate being arranged so that the carriage is movable in translation relative to the plate, along a translation axis (Z) perpendicular to the rolling plane, the height of the carriage relative to the rolling plane being continuously adjustable; - the carriage being movable in rotation relative to the plate, around an axis of rotation (A) parallel to the rolling plane;- so that the position of the carriage can vary, relative to the rolling plane, in rotation, along the axis of rotation, and in translation, along the axis of translation; the carrier being such that the carriage is connected to the plate by a worm screw (12), extending parallel to the axis of translation (Z), so that a rotation of the worm screw causes the translation of the carriage.;

2. A carrier according to claim 1, wherein the worm screw is manually actuable.

3. Carrier according to any one of the preceding claims, in which the carriage is continuously orientable according to a plurality of angles of rotation around the axis of rotation.

4. Carrier according to any one of the preceding claims, in which the carrier comprises a control unit (40), intended to be connected to the detector, the control unit being configured to generate a setpoint signal for the position of the detector as a function of a detection signal resulting from the detector.

5. A carrier according to any preceding claim, comprising at least one location unit (7), configured to establish a distance between the carrier and a reference object, the distance being determined parallel to the rolling plan.

6. A carrier according to claim 5, wherein the location unit comprises at least one rangefinder (7X, 7Y).

7. Carrier according to any one of the preceding claims, comprising a three-dimensional camera, integral with the carrier (1), and configured to acquire three-dimensional geometric data in the field of observation of the radiation detector.

8. Method for arranging a detector (30) using a carrier (1) according to any one of the preceding claims, the method comprising: a. arranging the detector (30) on the carriage (20); b. taking into account a height, along the translation axis, and an orientation of the detector, around the rotation axis, relative to an object to be controlled; c. controlling the translation and rotation of the carriage to reach the predetermined height and orientation.

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