Surface radiological contamination detection robot, its detection method and program

Abstract

The invention relates to an autonomous robot for detecting radiological contamination emanating from a surface, comprising a control unit configured to prescribe (E0, E1, E2, E3, E8) a speed (V) of movement and a measurement time (Fi, Fi+1) for the gamma radiation detection probe, to control (E4) the movement system (2) along a first path (T1) at the speed (V), and to control the probe (4) to measure a first number (M) of detected counts during the time (Fi, Fi+1) during the first path (T1), to calculate (E4) a gamma radiation emission activity (A) as a function of the number (M), and, if the activity (A) is below the prescribed activity threshold (SA), to control the wireless transceiver (5) transmitting (E6) an information (INF1) indicating the absence of detection of radiological contamination; otherwise, to control the transceiver (5) transmitting (E7) an information (INF2) indicating the detection of radiological contamination.Figure for the abbreviation: Figure 4A.

Description

Title of the invention: Robot for detecting surface radiological contamination, its detection method and program

[0001] The invention relates to an autonomous robot for detecting radiological contamination emanating from a surface, a method for detecting radiological contamination emanating from a surface, and a computer program for implementing the method.

[0002] The field of the invention concerns metrology in radiation protection, in particular for monitoring soil and road contamination, in order to determine the presence or absence of artificial radioactivity.

[0003] Current regulations require periodic checks to be carried out on roads likely to carry radioactively contaminated material. These road checks must ensure that radioactive contamination does not disperse outside the site and into the ground (regulatory requirement).

[0004] One area of ​​application concerns, in particular, nuclear power plants for the production of electricity. In these, basic nuclear installations (INB) and installations classified for environmental protection (ICPE) define a traffic plan for means of transport transporting hazardous materials on their site. The roads concerned by the circulation of radioactive materials are those which will be subject to the annual road inspection.Some areas are subject to more frequent inspections, in particular the part of the roadway under various buildings of a nuclear power plant (abbreviated as: BR (Reactor Building), BK (Fuel Building), BAN (Nuclear Auxiliary Building), BW (Operating Building), BTE (Effluent Treatment Building), the areas in front of the exit airlocks of ZppDN zones (abbreviation for: zone with potential nuclear waste production) of the BK, BAN, BW, BTE buildings, laundry, hot workshop, transport control building and the areas near the storage areas. The frequency of inspections is adapted according to the type of unit shutdown, the volume and the type of activities. In addition, it is prescribed to carry out non-contamination checks of the areas adjacent to the ZppDN exit airlocks (airlocks designated by the name ex-DI82) used following the internal transfer of oversized equipment such as TN12 (disposal of spent fuel).

[0005] Radiological contamination detection devices are known, pulled manually by a person or pulled by a motorized vehicle driven by a person and using a measurement by detecting beta radiation coming from the surface.

[0006] These devices have the disadvantage of a low penetration capacity of beta radiation in the surface material to be detected, which means that beta detection is less suitable for wet floors, as the water can shield the beta radiation from the surface.

[0007] These devices also have the disadvantage of having to keep the distance between their beta radiation detector and the ground small, or even in near contact with the ground, which requires monitoring by the person using the device and presents risks of damage to the beta radiation detector if the device passes over a surface with projections, due for example to the presence of objects or materials on the ground or roadway, or to deterioration of the surface. These devices thus have the disadvantage of being fragile and lacking in robustness, and therefore generating high maintenance costs.

[0008] Another disadvantage of these devices is that the person using them is constantly busy intensively monitoring the measurement parameters (speed and ground / detector distance), which turns out to be a time-consuming task.

[0009] An objective of the invention is to obtain an autonomous robot for detecting radiological contamination emanating from a surface, a method for detecting radiological contamination emanating from a surface, as well as a computer program for implementing the method, which overcome the drawbacks mentioned above.

[0010] To this end, a first object of the invention is an autonomous robot for detecting radiological contamination emanating from a surface, the robot comprising: a system for moving the robot along or on the surface, a system for providing a position of the robot relative to the surface during a measurement, at least one gamma radiation detection probe, which has a gamma radiation detection diameter against the surface and which is capable of measuring counts detected in the detection diameter in response to the gamma radiation, a wireless transceiver, a robot control computer, configured to perform the following steps: prescribing a movement speed of the robot movement system and a measurement duration of the gamma radiation detection probe, controlling the movement system to move the robot along a first path at the prescribed speed forward along the surface or on the surface and controlling the probe to measure a first number of counts detected in the detection diameter during the prescribed measurement time during the first path, calculating a gamma radiation emission activity based on the first number of counts detected by the probe, compare the gamma radiation emission activity to a prescribed threshold of activity, for in the case where the gamma radiation emission activity is less than the prescribed activity threshold, controlling the wireless transceiver so that the wireless transceiver transmits a first piece of information indicating the absence of detection of radiological contamination, in the case where the gamma radiation emission activity is greater than or equal to the prescribed activity threshold, controlling the wireless transceiver so that the wireless transceiver transmits a second piece of information indicating the detection of radiological contamination.

[0011] The invention makes it possible to carry out surface checks for radiological contamination, such as for example potentially polluted soils or roads in a nuclear power plant for producing electricity. Thanks to the invention, gamma radiological contamination emitted by a radionuclide at, or below, the surface can be rapidly detected.

[0012] An advantage of the invention is that it makes it possible to overcome the condition of the surface, for example the ground or the road. Dustiness or roughness of the road surface is no longer a constraint, given that gamma radiation is being measured. Similarly, weather conditions, in particular the presence of moisture on the ground, are no longer considered problematic and as distorting the measurement. In addition, certain radionuclides that do not emit beta particles, but alpha particles as well as gamma radiation, can be detected. The method therefore makes it possible to extend the detection field. Gamma radiation can pass through materials, which makes it possible to measure the radioactivity of the surface, even if this surface is wet. This makes it possible to increase the overall availability of the measuring device and to carry out road inspections as close as possible to the need.

[0013] The invention makes it possible to avoid having to keep the distance between the gamma radiation detection probe and the surface small and has the advantage of high robustness and low maintenance and personnel costs. Gamma radiation can be detected at a greater distance than beta radiation (penetration into matter), which means that it is not necessary to place the gamma radiation detection probe in close contact with the surface or the ground. This limits the impacts of the gamma radiation detection probe with road defects or objects and materials present on the roads.

[0014] The invention makes it possible to avoid monopolizing a person who must be on the vehicle moving the gamma radiation detection probe to carry out the measurements.

[0015] According to one embodiment of the invention, the robot control computer is configured to, at each iteration of a first loop: in a first step, command the movement system to move the robot along at least a second path at the prescribed speed forward along the surface or on the surface and controlling the probe to measure a second number b; of detected hits in the detection diameter during the prescribed measurement time F; during the second path, in a second step, calculate a minimum detectable SDMC activity of gamma radiation emission, proportional to , during the prescribed duration F i of measurement, in a third step, comparing the minimum detectable SDMC gamma radiation emission activity to the prescribed activity threshold SA, for in the case where the minimum detectable SDMC gamma radiation emission activity is lower than the prescribed activity threshold SA: at each iteration of a second loop, during a fourth step, controlling the movement system to move the robot along the first path at the prescribed speed forward along the surface or on the surface, controlling the probe to measure the first number M of detected counts in the detection diameter during the prescribed measurement time during the first path and calculating the gamma radiation emission activity as being proportional to the first number M of detected counts, from which the second number b; of detected counts is subtracted, in a fifth step, compare the gamma radiation emission activity to the prescribed activity threshold SA, for in the event that the gamma radiation emission activity is below the prescribed activity threshold SA, controlling the wireless transceiver so that the wireless transceiver transmits the first information indicating the absence of detection of radiological contamination by the wireless transceiver during a sixth step and returning to the fourth step to carry out a subsequent iteration of the second loop, in the case where the gamma radiation emission activity is greater than or equal to the prescribed activity threshold SA, command the wireless transceiver so that the wireless transceiver transmits the second information indicating the detection of radiological contamination during a seventh step, in the case where the minimum detectable gamma radiation emission activity SDMC is greater than or equal to the prescribed activity threshold SA: during an eighth step modify the prescribed duration F; of measurement into a prescribed duration Fi+i of measurement modified according to p _ SDMCF, , modify the prescribed speed of the second robot path, corresponding to the prescribed duration Fi+i of modified measurement, the along the surface or on the surface at a prescribed speed V2 modified according to y _ Diam , where Diam is the detection diameter, then return to the first step “ Fi+i to perform a subsequent iteration of the first loop according to the modified prescribed measurement duration Fi+i and according to the modified prescribed speed V2.

[0016] According to one embodiment of the invention, the second path is initialized at a prescribed zone of absence of radiological contamination of the surface having a prescribed initial position against the surface during a first iteration of the first loop.

[0017] According to an embodiment of the invention, the first information further contains the gamma radiation emission activity having been calculated and / or an uncertainty u(A) on the gamma radiation emission activity (A) according to u(A) = •

[0018] According to one embodiment of the invention, the minimum detectable SDMC activity is calculated according to d^tÿSA, SDMC = F.SCR^- Or d is a determined index of the probe's sensitivity, SCR is a conversion factor determined from the probe to the number of counts per SA threshold of activity.

[0019] According to one embodiment of the invention, the activity threshold SA is greater than or equal to 200 Bq and is less than or equal to 2000 Bq.

[0020] According to one embodiment of the invention, the robot control computer is configured to, following the seventh step: during a ninth step, controlling the movement system to move and then immobilize the robot in a fixed position located a prescribed length greater than or equal to at least one first backward path against the surface, during a tenth step, controlling the probe immobilized in the fixed position to carry out the measurement of N numbers rO[j] of detected counts during N successive prescribed time windows Fj of measurement of equal durations D, where N is a determined natural integer, greater than or equal to 2, and j is a natural integer ranging from 1 to N, during an eleventh step, calculate an average rO of the N numbers rO[j] of detected hits, in a twelfth step, calculate a probe measurement time tg as a function of the mean rO, the threshold SA, N and D, and modify the displacement speed of the robot displacement system to a modified prescribed speed V3 according to V, = fl-!'1.! . 3 tg

[0021] According to one embodiment of the invention, the robot control computer is configured to, following the twelfth step, at each iteration of a third loop: in a thirteenth step, controlling the movement system to move the robot along a third path at the modified prescribed speed V3 forward along the surface or on the surface and controlling the probe to measure a third number rg of detected strokes in the detection diameter during the prescribed measurement time tg during the third path, in a fourteenth step, calculating a running average rg' of the third number rg of counts detected during the prescribed measurement time tg, and calculating a modified gamma radiation emission activity as being proportional to the running average rg', from which the average rO is subtracted.

[0022] According to one embodiment of the invention, the duration D is less than or equal to the duration F; or to the duration Fi+[.

[0023] According to one embodiment of the invention, the modified prescribed speed V3 is lower than the modified prescribed speed V2.

[0024] According to one embodiment of the invention, t*? =----£2----where k is a parameter [ ( V ) "Ni) ] prescribed.

[0025] According to one embodiment of the invention, the robot control computer is configured to, following the fourteenth step: in a fifteenth step, compare the modified gamma radiation emission activity with the prescribed activity threshold, for in the event that the modified gamma radiation emission activity is below the prescribed activity threshold, controlling the wireless transceiver so that the wireless transceiver transmits in a sixteenth step a third information containing the modified gamma radiation emission activity and / or an uncertainty on the modified gamma radiation emission activity, in the case where the modified gamma radiation emission activity is greater than or equal to the prescribed activity threshold, controlling the wireless transceiver so that the wireless transceiver transmits during a seventeenth step a fourth information, indicating the detection of radiological contamination and containing the modified gamma radiation emission activity and / or an uncertainty on the modified gamma radiation emission activity.

[0026] According to one embodiment of the invention, the robot control computer is configured to, following the sixteenth step and following the seventeenth step: during an eighteenth step, determine whether the position corresponds to a measurement already carried out during at least one first trip, for: in the case where the position corresponds to the measurement by the at least one first path, return to the thirteenth step to perform a next iteration of the third loop, in case the position does not match the measurement by the at least one first path, return to the first step to perform a next iteration of a fourth loop.

[0027] According to one embodiment of the invention, the gamma radiation detection probe is located at a prescribed distance of at least 5 cm above a contact surface of the displacement system with the surface.

[0028] According to one embodiment of the invention, the control computer comprises a memory and is configured to record the measurement and / or the gamma radiation emission activity and / or the first information or the second information and / or the third information or the fourth information in association with the position, having been determined by the position supply system (3) during the measurement.

[0029] A second object of the invention is a method for detecting radiological contamination emanating from a surface using the autonomous robot as described above, characterized in that the method comprises said steps, implemented by the robot's control computer.

[0030] A third subject of the invention is a computer program, comprising code instructions for implementing the method for detecting radiological contamination emanating from a surface as described above, when the program is executed on a computer.

[0031] The invention will be better understood on reading the description which follows, given solely by way of non-limiting example with reference to the figures below of the attached drawings.

[0032] [Fig-1] represents a schematic perspective front view of an autonomous robot for detecting radiological contamination according to an embodiment of the invention.

[0033] [Fig.2] represents a schematic top view of paths of an autonomous robot for detecting radiological contamination according to an embodiment of the invention.

[0034] [Fig.3] represents a schematic side view of a part of an autonomous robot for detecting radiological contamination according to an embodiment of the invention.

[0035] [Fig.4A] represents a first part of a flowchart of a method for detecting radiological contamination according to an embodiment of the invention, continuing from B to [Fig.4B].

[0036] [Fig.4B] represents a second part of a flowchart of the method for detecting radiological contamination according to an embodiment of the invention, continuing from B of [Fig.4A]. [Fig.4B] continues from C to [Fig.4A].

[0037] An example of an autonomous robot for detecting radiological contamination is described in more detail below with reference to [Fig.l].

[0038] The autonomous robot 1 is intended to move against a surface, in order to detect and / or measure radiological contamination emanating from this surface S. The surface S may be, for example, the ground (road, pavement or other), but also a wall or a ceiling. Thus, one or more radionuclides emitting gamma radiation, called a source S' of radiological contamination, may be present in unknown locations under the surface S or on the surface S.

[0039] The autonomous robot 1 comprises a system 2 for moving the robot 1 along the surface S or on the surface S. This system comprises, for example, at least three or four wheels 21, 22, 23, 24 for rolling against the surface S (arranged in a quadrilateral in top view) and means for holding the wheels against the surface S in the case where the surface S is sloping or vertical or a ceiling. The wheels 21, 22, 23, 24 are rotatably mounted about a horizontal axis on a chassis 25 of the robot 1. At least one, several or all of the wheels 21, 22, 23, 24 is driven and is capable of being driven in rotation against the surface S by a motor 7 present in the chassis 25, to move the robot 1 along the surface S or on the surface S forward in the forward direction XI of a longitudinal direction X parallel to the surface S and backward in the rear direction X2 of the longitudinal direction X relative to the surface S.Figures 1 and 2 also show the direction Z normal to the surface S, the transverse direction Y, which is parallel to the surface S and perpendicular to the longitudinal direction X, as well as the direction Y1 to the left of the transverse direction Y and the direction Y2 to the right of the transverse direction Y. At least one or more of the wheels 21, 22, 23, 24, such as for example the wheel 21, is steered and is capable of being steered to the left in the direction Y1 and to the right in the direction Y2 relative to the surface S by being driven around a pivot axis by a guide 8 or steering drive motor 8 connected to the chassis 25.

[0040] The autonomous robot 1 comprises, fixed to the chassis 25, a system 3 for providing a position P (at least one longitudinal coordinate along the longitudinal direction X and one transverse coordinate along the transverse direction Y) of the robot 1 relative to the surface S during a measurement.

[0041] The position supply system 3 P may comprise one (or more) position sensors 31 by reflectometry, which may for example be of the LIDAR type (acronym for detection and estimation of distance by light or by laser), allowing a measurement of the distance relative to a known reference point in the environment, based on the analysis of the time of flight of a beam of light or laser emitted by a transmitter of the sensor towards the known reference point then reflected towards a receiver of the sensor). The sensor 31 is connected to a calculation unit to measure the position P from the signals measured by the sensor 31.

[0042] The position supply system 3 P may comprise, in addition to or instead of the sensor 31, a position sensor 32 by GPS positioning (acronym for Geopositioning by satellite).

[0043] The autonomous robot 1 comprises, fixed to the chassis 25, one (or more) probes 4 for detecting gamma radiation. [Fig. 3] represents a path T of the same probe 4 during a movement of the robot 1 against the surface S, from a position PI to a position P2, the rest of the robot 1 not being represented. Each probe 4 has a diameter Diam, non-zero, for detecting gamma radiation against the surface S (scanned zone ZD formed by the circle of diameter Diam on the surface S). Each probe 4 is capable of measuring counts detected in response to the gamma radiation emitted by the surface S in the detection diameter Diam.The probe 4 has a gamma radiation receiver 41, having a non-zero detection cone 40, centered on a center 42 of the receiver 41, which is located at a prescribed height h0, non-zero, along the normal direction Z relative to an orthogonal projection 120 of the contact zone 20 of the robot 1 with the surface S (lower contact zone 20 of the wheels 21, 22, 23, 24 with the surface S). The detection cone 40 is delimited by the diameter Diam of detection and makes it possible to capture the gamma radiation which is emitted from the scanned zone ZD of the surface S and which is directed in the detection cone 40 towards the center 42 of the receiver 4L The gamma radiation detection probe(s) 4 can be arranged at the front of the robot 1. The probe 4 can be covered on top by a sealing cap and be hermetically sealed (particularly against moisture) in a protective housing.For example, two gamma radiation detection probes 4 may be provided, located side by side in the transverse direction Y. The movement system 2 allows the robot 1 to scan the surface S in successive positions at least in the forward direction XI to bring the probe 4 and its scanned area ZD in front of the source S' of contamination of the surface S, so that the probe 4 captures the gamma radiation which is emitted by the source S' of contamination of the surface S.

[0044] The gamma radiation detection probe 4 may be located at the prescribed height hO of at least 5 cm above a contact surface 20 of the displacement system 2 with the surface S. The height hO may be greater than or equal to 5 cm and less than or equal to 20 cm. In particular, the height hO may be greater than or equal to 10 cm. For example, the height hO may be approximately 15 cm. The diameter of the wheels 21, 22, 23, 24 may be greater than or equal to 10 cm and less than or equal to 30 cm. For example, the diameter of the wheels 21, 22, 23, 24 may be equal to 30 cm.

[0045] The detection diameter Diam can be greater than or equal to 7 cm and less than or equal at 80 cm. For example, the detection diameter Diam can be equal to 50 cm.

[0046] The gamma radiation detection probe(s) 4 may be a scintillation or scintillator probe. In one example, the gamma radiation detection probe(s) 4 may be an inorganic scintillator probe. For example, the inorganic scintillator may comprise a measuring material containing NaI(Tl) (sodium iodide, doped with thallium). In another example, the inorganic scintillator may comprise a measuring material containing CSI(Tl) (cesium iodide, doped with thallium). In another example, the gamma radiation detection probe(s) 4 may be a plastic or organic scintillator probe. Alternatively, the gamma radiation detection probe(s) 4 may be a gaseous or semiconductor detector probe.

[0047] The measurement of the gamma radiation emission activity A during step E4 (and when provided also the minimum detectable gamma radiation emission activity SDMC during step E1) can be carried out for a determined radionuclide of interest, emitting gamma radiation from the surface S. The threshold SA may have been prescribed for this determined radionuclide of interest. The probe 4, as in the examples above, can be configured to detect different energy levels of the received gamma radiation. This allows the probe 4 to detect different radionuclides of interest, to distinguish them and to make a measurement of the number of detected counts (b; and when provided also M) for a determined radionuclide of interest or for each of several determined radionuclides of interest. For example, a determined radionuclide of interest may be 60Co. Another determined radionuclide of interest may be 137Cs.

[0048] The measurement of the gamma radiation emission activity A during step E4 (and when it is also provided the minimum detectable SDMC gamma radiation emission activity during step E1) can be calibrated for a determined radionuclide of interest, called reference. This determined reference radionuclide of interest, perhaps for example 60Co. To carry out this calibration, a known quantity of the determined reference radionuclide of interest is placed in the surface at a known location and the robot 1 carries out the measurements at this location and the values ​​of the gamma radiation emission activity A (and when it is also provided the minimum detectable SDMC gamma radiation emission activity during step E1) are then calculated to have prescribed values ​​as a function of the known quantity of the determined reference radionuclide of interest.

[0049] The SCR conversion factor, described below, makes it possible to calculate the gamma radiation emission activity A for a determined radionuclide of interest, other than the determined reference radionuclide of interest, from the first number M of detected counts. The SCR conversion factor is determined and / or prescribed and / or preen recorded in a memory 61 of the calculator 6. The SCR conversion factor varies according to the probe 4.

[0050] The overall conversion factor K, described below, makes it possible to calculate, when it is provided, the minimum detectable SDMC activity of gamma radiation emission for a determined radionuclide of interest, other than the determined reference radionuclide of interest, from the second number b; of detected counts. The overall conversion factor K is determined and / or prescribed and / or pre-recorded in the memory 61 of the computer 6.

[0051] The autonomous robot 1 comprises, fixed to the chassis 25, a wireless transceiver 5 (having a transceiver antenna 51), making it possible to send information to a remote station 1000 and to receive information from the remote station 1000. A detection device may comprise the autonomous robot 1 and the remote station 1000.

[0052] The autonomous robot 1 comprises, fixed to the chassis 25, a computer 6 for controlling the robot 1. The control computer 6 is configured to carry out the steps described below, with reference to FIGS. 4A and 4B. A method for detecting radiological contamination emanating from the surface S using the autonomous robot 1 comprises the steps described below, implemented by the computer 6 for controlling the robot 1, with reference to FIGS. 4A and 4B. The control computer 6 may be or comprise one (or more) computers, one (or more) processors, one (or more) microprocessors, one (or more) control circuits or others. The control computer 6 may have been programmed by a computer program, comprising code instructions for implementing the method, when it is implemented on this computer, with reference to FIGS. 4A and 4B.

[0053] A first embodiment of certain steps is first described below. The first embodiment makes it possible to detect radiological contamination of the surface S.

[0054] During the preliminary steps E0, El (and possibly E2, E3, E8), the computer 6 prescribes a speed V of movement of the system 2 for moving the robot 1 and a duration F; or Fi+i of measurement of the probe 4 for detecting gamma radiation.

[0055] During step E0, the prescribed measurement duration F; may be initialized by the computer 6 to an initial value, which may be prescribed or pre-recorded in the memory 61 of the computer 6. According to a non-limiting example, this initial value of the prescribed measurement duration F; may be equal to 25 cm / s.

[0056] Then, during step E4, the computer 6 controls the movement system 2 to move the robot 1 along a first path Ti (or sweep) at the prescribed speed V forward (in the direction XI) along the surface S or on the surface S. The computer 6 controls the probe 4 to measure a first number M of strokes detected in the detection diameter Diam during the prescribed duration F; or Fi+i of measurement during the first path Th The system 3 for providing the position of the robot 1 provides different positions P of the robot 1 and the probe 4 along the first path Th

[0057] During step E4, the computer 6 calculates an activity A of gamma radiation emission as a function of the first number M of counts detected by the probe 4.

[0058] Then, during step E5, the computer 6 compares the gamma radiation emission activity A to a prescribed activity threshold SA. The prescribed activity threshold SA is a screening threshold for radiological contamination. The prescribed activity threshold SA makes it possible to decide, in steps E5, E6 and E7, whether at position P the scanned area ZD of the surface S is contaminated or not.

[0059] In the case where (YES in step E5), in step E5, the computer 6 determines that the gamma radiation emission activity A is lower than the prescribed activity threshold SA, i.e. that A < SA, the computer 6 controls the wireless transceiver 5 so that the wireless transceiver 5 transmits during step E6 a first item of information INF1 indicating the absence of detection of radiological contamination. The gamma radiation emission activity A corresponds to the gamma radiation emission activity emitted locally by the surface S at the position P and measured by the probe 4.

[0060] In the case where (NO in step E5), in step E5, the computer 6 determines that the gamma radiation emission activity A is greater than or equal to the prescribed activity threshold SA, i.e. that A > SA, the computer 6 controls the wireless transceiver 5 so that the wireless transceiver 5 transmits during step E7 a second information INF2 indicating the detection of radiological contamination. The second information INF2 may contain an alarm AL. The threshold SA is a real expressed in Bq (Becquerel) or s1. The gamma radiation emission activity A is a real expressed in Bq (Becquerel) or s1. During step E7, the computer 6 controls the movement system 2 to stop the robot 1 (position P3 in [Fig.2]).

[0061] This first embodiment of the steps described above allows the robot to check whether radiological contamination (or ionizing or radioactive contamination) is present locally at position P on surface S, without requiring the presence of a person at this location on the surface. The first embodiment makes it possible to warn the user in the event of detection of this radiological contamination, by sending him the information INF2 remotely.

[0062] For each measurement of the number M carried out by the probe P and / or for each activity A of gamma radiation emission calculated by the computer 6, the position P, determined by the system 3 for providing the position P of the robot 1 can be associated or recorded in the memory 61 of the computer 6 with the measurement of the number M and / or with the gamma radiation emission activity A calculated by the computer 6 and / or with the first information INF1 or with the second information INF2. The robot 1 thus makes it possible to map the surface S by successively passing through several positions P along the surface S or on the surface S. The robot 1 thus makes it possible to calculate the gamma radiation emission activity A for each position P where the robot 1 passes.

[0063] A second embodiment of certain additional steps compared to the first embodiment is described below. The second embodiment makes it possible to remove a measurement b; taking into account the background noise.

[0064] According to the second embodiment of the invention, the control computer 6 of the robot 1 is configured to carry out the following steps, at each iteration of a first loop Bh

[0065] During the first step E1, the computer 6 controls the movement system 2 to move the robot 1 along at least a second path T2 (or sweep) at the prescribed speed V forward along the surface S or on the surface S and control the probe 4 to measure a second number b; of detected strokes in the detection diameter Diam during the prescribed measurement duration E during the second path T2. The position supply system 3 of the robot 1 provides different positions P of the robot 1 and the probe 4 along the second path T2.

[0066] The second path T2 can be initialized at a prescribed zone Z0 of absence of radiological contaminations of the surface S having a prescribed initial position PO against the surface S during a first iteration of the first loop Bh

[0067] During the second step E2, the computer 6 calculates a minimum SDMC activity of gamma radiation emission, which is detectable during the prescribed measurement duration F;. This minimum detectable SDMC activity of gamma radiation emission is proportional to . The computer 6 calculates the activity SDMC minimum detectable gamma radiation emission, as equal to multiplied by the overall conversion factor K, i.e.

[0068] SDMC = K-^

[0069] The overall conversion factor K is determined and / or pre-recorded in the memory 61 of the computer 6.

[0070] For example, the calculator 6 calculates the overall conversion factor K as being equal to

[0071] K . d-SA “ scr^;

[0072] where d is a determined index (and / or pre-recorded in the memory 61 of the computer 6) of sensitivity of the probe 4 to gamma radiation and is a real number without unit, es is an efficiency of the probe 4 (efficiency of the meter) determined (and / or pre-recorded in the memory 61 of the computer 6), SCR is the conversion factor in counts per threshold SA.

[0073] We therefore have in this example:

[0075] In this example, the calculator 6 can calculate a number s; of minimum detectable net counts, observed during the prescribed measurement duration F;, according to

[0076] s^d'-Tb"

[0077] Then, the calculator 6 can calculate a minimum count rate MDCRS, which is detectable during the prescribed measurement time F;, according to

[0078] MDCR. = -4=

[0079] Then, the calculator 6 can calculate the minimum detectable SDMC activity of gamma radiation emission, according to

[0080] SDMC = • SA

[0081] For example, in embodiments of the invention, the activity threshold SA may be greater than or equal to 15 Bq and less than or equal to 2000 Bq. For example, the activity threshold SA may be equal to 800 Bq.

[0082] For example, in embodiments of the invention, the statistical performance index d' may be greater than 0 (especially greater than or equal to 0.1) and less than or equal to 3.28. For example, the statistical performance index d' may be equal to 1.38.

[0083] For example, in the embodiments of the invention, the efficiency es of the probe 4 may be greater than 0 (in particular greater than or equal to 0.1) and less than or equal to 1. For example, the efficiency es of the probe 4 may be equal to 1.

[0084] For example, in embodiments of the invention, the SCR conversion factor may be greater than or equal to 1 count per activity threshold SA and less than or equal to 10,000 counts per activity threshold SA. For example, the SCR conversion factor may be equal to 10 counts per activity threshold SA, and for example to 10 counts per 800 Bq. The value of 800 Bq may correspond to the presence of a point source of 800 Bq of cobalt 60 on the surface S, called the reference radionuclide. Of course, the reference radionuclide could be other than cobalt 60.

[0085] During the third step E3, the calculator 6 compares the minimum detectable gamma radiation emission activity SDMC to the prescribed activity threshold SA.

[0086] In the case (YES in step E3) where, during the third step E3, the calculator 6 determines that the minimum detectable gamma radiation emission activity SDMC is less than the prescribed activity threshold SA, i.e. SDMC < SA. the computer 6, at each iteration of a second loop (B2), during the fourth step E4, controls the movement system 2 to move the robot 1 along the first path Ti (or scan) at the prescribed speed V forward along the surface S or on the surface S, controls the probe 4 to carry out the measurement of the first number M of counts detected in the detection diameter Diam during the prescribed measurement duration F; during the first path Ti and calculates the gamma radiation emission activity A according to as being proportional to the first number M of counts detected during the measurement, from which is subtracted the second number b; of counts detected during the acquisition of the background noise, according to

[0087] A=(M-bi).SCR

[0088] After the fourth step E4, the computer 6 performs the fifth step E5 described above.

[0089] In the case where (YES in step E5), in step E5, the computer 6 determines that the gamma radiation emission activity A is lower than the prescribed activity threshold SA, i.e. that A < SA, the computer 6 controls the wireless transceiver 5 so that the wireless transceiver 5 transmits during the sixth step E6 described above the first information INF1 indicating the absence of detection of radiological contamination, then returns to the fourth step E4 to carry out a following iteration of the second loop B2.

[0090] In the case where (NO in step E5), in step E5, the computer 6 determines that the gamma radiation emission activity A is greater than or equal to the prescribed activity threshold SA, i.e. that A > SA, the computer 6 controls the wireless transceiver 5 so that the wireless transceiver 5 transmits during the seventh step E7 described above the second information INF2 indicating the detection of radiological contamination.

[0091] In the case where (NO in step E3), in the third step E3, the calculator 6 determines that the minimum detectable gamma radiation emission activity SDMC is greater than or equal to the prescribed activity threshold SA, i.e. that SDMC > SA, the calculator 6, during an eighth step E8, modifies the prescribed measurement duration F; into a modified prescribed measurement duration Fi+i according to

[0092] F _ SDMCFj r i+1 “ SA

[0093] During this step E8, the computer 6 modifies the prescribed speed V of the second path T2 of the robot 1 along the surface S or on the surface S into a modified prescribed speed V2 according to

[0094] y - Dhjm 2 Fkl

[0095] This modified prescribed speed V2 corresponds to the path of the detection diameter Diam during the modified prescribed measurement duration Fi+i by the second path T2 along the surface S or on the surface S in the forward direction XI. Then, after step E8, the computer 6 returns to the first step El, to carry out a following iteration of the first loop Bi by taking the modified prescribed measurement duration Fi+i instead of the prescribed measurement duration F; and by taking the modified prescribed speed V2 instead of the prescribed speed V in this following iteration of the first step El. The following iteration(s) make it possible to calculate the modified prescribed speed V2 such that the minimum detectable gamma radiation emission activity SDMC is lower than the prescribed activity threshold SA, i.e. SDMC < SA.

[0096] Steps E1, E2, E3 make it possible to measure a background noise, formed by the second number b; of detected counts, the number s; of minimum detectable net counts, the minimum count counting rate MDCRS and the minimum detectable gamma radiation emission activity SDMC. This background noise is that present globally against the surface S. This minimum count counting rate MDCRS is corrected to the minimum detectable gamma radiation emission activity SDMC by taking into account by K a desired performance coefficient to compensate for the type I and type II error rates which can be for example 0.05 and 0.6, respectively, which means less than 5% of false negatives and less than 60% of false positives. A high rate of false positives is easily tolerated due to the two scanning steps E1 and E4 described, where a pause for measurements with a duration Fi+i longer than the duration F; occurs.The variable given as the efficiency of the meter can avoid being conservative in the calculations, this factor being equal to a maximum of 1 when using a robot, against a minimum of 0.5 in the case of a human operator.

[0097] The minimum detectable gamma radiation emission activity SDMC is determined from the minimum count count rate MDCRS by applying the conversion factor SCR which takes into account the size of the NaI(Tl) crystals of the detector in one of the examples above and the gamma energy(s) of the radionuclide of interest emitting gamma radiation from the surface S. The minimum count count rate MDCRS takes into account the background noise level, the performance criteria (d1) and the observation interval (duration F; or Fi+i). The observation interval (duration F; or Fi+i) during the scanning of step E1 or E4 is the real time during which the detector of the probe 4 can respond to the source of contamination of the surface S. This interval depends on the measurement speed V and the diameter Diam of the scanned area ZD.

[0098] During the first loop Bb, the computer 6 of the robot 1 therefore adapts the speed V2 to the background noise present in order to respect SDMC < SA.

[0099] The invention makes it possible to reduce human errors. Risks are reduced by controlling the speed V2 according to the background noise. This leads to better precision, reproducibility and reliability in the execution of road inspections.

[0100] The prescribed measurement duration F; can be initialized to a determined value, which is prescribed and / or pre-recorded in the memory 61 of the computer 6 during step E0. This determined value can be equal to two seconds for example.

[0101] In the above, during the sixth step E6, the first information INF1 may further contain the gamma radiation emission activity A having been calculated and / or an uncertainty u(A) on the gamma radiation emission activity A according to

[0102] u(A)=^Â

[0103] A third embodiment of certain additional steps compared to the first embodiment or the second embodiment is described below. The third embodiment makes it possible to calculate more precisely a gamma radiation emission activity A' and to validate or invalidate the second information INF2 indicating the detection of radiological contamination. The third embodiment of the invention is carried out by the control computer 6 of the robot 1 following the seventh step E7.

[0104] According to the third embodiment of the invention, following the seventh step E7, the computer 6 controls during a ninth step E9 the movement system 2 to move the robot 1 back to a fixed position PF located at a prescribed length L, which is greater than or equal to the first path Ti (or to the first paths TJ backward in the direction X2 against the surface S. The computer 6 controls the movement system 2 to immobilize the robot in this fixed position PF.

[0105] Then, during a tenth step E10, the computer 6 controls the probe 4 immobilized in the fixed position PF to carry out the measurement of N numbers rO[j] of detected counts during N successive prescribed time windows Fj of measurement of equal durations D. N is a determined natural integer, greater than or equal to 2, and j is a natural integer ranging from 1 to N. The integers N and j are prescribed and / or pre-recorded in the memory 61 of the computer 6.

[0106] During an eleventh step El 1, the calculator 6 calculates an average rO of the N numbers rO[j] of detected counts. This average rO is considered to be the average of the background noise.

[0107] During a twelfth step E12, the computer 6 calculates a measurement duration tg of the probe 4 as a function of the average rO, the threshold SA, N and D. During the twelfth step E12, the computer 6 modifies the speed V of movement of the system 2 of movement of the robot 1 into a prescribed speed V3 modified according to

[0108] ^ / 3 = ¾21

[0109] The duration D may be less than or equal to the duration F; or to the duration Fi+i.

[0110] The modified prescribed speed V3 may be lower than the modified prescribed speed V2. Thus, the prescribed speed V3 is a slow speed compared to the speed V or V2 of steps E1 and / or E4.

[0111] During the twelfth step El2, the calculator 6 can calculate the measurement duration tg of the probe 4, such that the following condition is met:

[0112] k • + ~ < SA

[0113] where k is a prescribed parameter. The parameter k is prescribed and / or pre-recorded in the memory 61 of the computer 6.

[0114] For example, k is between 1.0 and 6.0. For example, k= 4.0.

[0115] The computer 6 of the robot 1 therefore adapts the speed V3 in order to respect the above condition on SA.

[0116] For example, to do this, during a twelfth step El2, the calculator 6 can calculate the measurement duration tg of probe 4 according to

[0117]

[0118] The third embodiment of the invention may comprise the following steps.

[0119] The calculator 6, following the twelfth step E12, at each iteration of a third loop B3 can perform the following steps.

[0120] During a thirteenth step E13 of the third loop B3, the computer 6 controls the movement system 2 to move the robot 1 along a third path T3 at the modified prescribed speed V3 forward along the surface S or on the surface S. During the thirteenth step E13 of the third loop B3, the computer 6 controls the probe 4 to measure a third number rg of detected strokes in the detection diameter Diam during the prescribed measurement time tg during the third path T3. The position supply system 3 of the robot 1 provides different positions P of the robot 1 and the probe 4 along the third path T3.

[0121] Then, during a fourteenth step E14 of the third loop B3, the computer 6 calculates a sliding average rg' of the third number rg of counts detected during the prescribed measurement duration tg, i.e. rg'=rg / tg.

[0122] The calculator 6 calculates a modified gamma radiation emission activity A' as being proportional to the running average rg', from which the background noise average rO is subtracted, i.e. according to

[0123] A' = (rg'-rO).SCR

[0124] The modified gamma radiation emission activity A' is a real expressed in Bq (Becquerel) or s'.

[0125] According to a non-limiting example, N=10 and D=1 second.

[0126] The measurement duration tg can be chosen at 6 seconds in this example.

[0127] The third embodiment of the invention may comprise the following steps.

[0128] The calculator 6, at the fourteenth step E14, at each iteration of the third loop B3, can perform the following steps.

[0129] During a fifteenth step E15 of the third loop B3, the computer 6 compares the modified gamma radiation emission activity A' to the prescribed activity threshold SA.

[0130] In the case where, in the fifteenth step E15, the computer 6 has determined that the modified gamma radiation emission activity A' is lower than the prescribed activity threshold SA, the computer 6 controls the wireless transceiver 5 so that the wireless transceiver 5 transmits during a sixteenth step E16 of the third loop B3 a third information item INF3 containing the modified gamma radiation emission activity A' and / or an uncertainty u(A') on the modified gamma radiation emission activity A'.

[0131] In the case where, in the fifteenth step E15, the computer 6 has determined that the modified gamma radiation emission activity A' is greater than or equal to the prescribed activity threshold SA, the computer 6 controls the wireless transceiver 5 so that the wireless transceiver 5 transmits during a seventeenth step E17 of the third loop B3 a fourth item of information INF4, indicating the detection of radiological contamination and containing the modified gamma radiation emission activity A' and / or an uncertainty u(A') on the modified gamma radiation emission activity A'. The fourth item of information INF4 may contain an alarm AL.

[0132] The third embodiment of the invention may comprise the following steps.

[0133] The calculator 6, following the sixteenth step E16 and following the seventeenth step E17, at each iteration of a third B3 loop can perform the following steps.

[0134] During an eighteenth step E18 of the third loop B3, the computer 6 determines whether the current position P of the step E13 corresponds to a measurement by the at least one first path Ti, that is to say whether the current position P, provided by the position supply system 3 of the robot 1 for the measurement step E13 is in a range of positions P where a measurement of the first number M of detected counts has already been carried out by the step E4 and where the gamma radiation emission activity A has been calculated.

[0135] In the case where the computer 6 has determined during the eighteenth step El8 of the third loop B3 (YES in step E18), that the current position P of step E13 corresponds to a measurement by the at least one first path Tb the computer 6 returns to the thirteenth step E13 to carry out a following iteration of the third loop B3.

[0136] In the case where the computer 6 has determined during the eighteenth step El8 of the third loop B3 (NO in step E18), that the current position P of step E13 does not correspond to a measurement by the at least one first path Tb the computer 6 returns to the first step El to perform a subsequent iteration of a fourth loop B4.

[0137] The calculator 6 can calculate during the sixteenth step E16 of the third loop B3 and during the seventeenth step E17 of the third loop B3 the uncertainty u(A') on the modified gamma radiation emission activity A' according to

[0138] uAA) = SCR2- (f + < ) +Â2-i^SCR^

[0139] Where u^^SCR) depends on the manufacturer's parameters of the detection probe used and can be prescribed or pre-recorded in the memory 61 of the computer 6, and

[0140] u(A') = ^m2( A')

[0141] In the memory 61 of the control computer 6 can be recorded the measurement M, b;, rO[j], rg, rg' and / or the gamma radiation emission activity A, A' and / or the first information INF1 or the second information INF2 and / or the third information INF3 or the fourth information INF4 in association with the position P, having been determined by the position supply system 3 during the measurement M, b,, rO[j], rg, rg' and / or the alarm AL.

[0142] The transceiver 5 can transmit to the remote station the measurement M, bi5 rO[j], rg, rg' and / or the activity A, A' of gamma radiation emission and / or the first information INF1 or the second information INF2 and / or the third information INF3 or the fourth information INF4 in association with the position P, having been determined by the position supply system 3 during the measurement M, bi5 rO[j], rg, rg' and / or the alarm AL.

[0143] The remote station 1000 may comprise an information presentation means 1001 for presenting to a user the measurement M, b,, rO[j], rg, rg' and / or the gamma radiation emission activity A, A' and / or the first information INF1 or the second information INF2 and / or the third information INF3 or the fourth information INF4 in association with the position P, having been determined by the position supply system 3 during the measurement M, b;, rO[j], rg, rg', and / or the alarm AL, for example on a map 1002 of the surface S. This information presentation means 1001 may be visual and / or audible. This information presentation means 1001 may comprise a display screen. The information presentation means 1001 can display on the screen a visual indication or determined icon of absence of radiological contamination (for example a green tile) associated with the information INF1 and / or INF3.The information presentation means 1001 may display on the screen a visual indication or determined icon of the presence of radiological contamination (for example a red tile) associated with the information INF2 and / or INF4. The remote station 1000 may be of the portable device type, which may be for example a computer, a tablet or a telephone. The remote station 1000 may. comprise control means for remotely controlling the robot 1. The remote station 1000 may comprise a memory 1003 for storing the measurement M, b,, rO[j], rg, rg' and / or the gamma radiation emission activity A, A' and / or the first information INF1 or the second information INF2 and / or the third information INF3 or the fourth information INF4 in association with the position P, having been determined by the position supply system 3 during the measurement M, bi5 rO[j], rg, rg', and / or the alarm AL, for example on a map 1002 of the surface S, or more generally for storing the values ​​recorded in the memory 61 of the computer 6.

[0144] Step E10 of the third embodiment of the invention makes it possible to measure a background noise, formed by the numbers rO[j] of detected counts. The measurement of the gamma radiation emission activity A' is thus made insensitive to the background noise.

[0145] The third embodiment of the invention overcomes another drawback of known devices, which is their high background noise. In certain environments, there may be high background noise due to sources of natural or artificial radioactivity, which may make it more difficult for these known devices using beta radiation detectors to accurately detect beta radiation of interest from the surface.

[0146] The third embodiment of the invention makes it possible to reduce human errors. Risks are reduced by controlling the speed V3 according to the background noise. This leads to better accuracy, reproducibility and reliability in the execution of road inspections.

[0147] The robot 1 may comprise anti-obstacle elements, such as for example a guard 26 at the front of the wheels 21, 22, 23 and a guard 27 at the rear of the wheels 22, 23, 24.

[0148] The robot 1 may comprise a starting element 28 on the chassis 25, such as for example a starting key.

[0149] The robot 1 may include on the chassis 25 one or more additional connectors 29, to be able to connect additional sensors, to be carried by the chassis 25.

[0150] The robot 1 may include an emergency stop button 30 on the chassis 25.

[0151] The robot 1 comprises in the chassis 25 an electricity supply battery, making it possible to supply energy to the computer 6, the sensor 4, the systems 2 and 3, the wireless transmitter-receiver (5) and the elements carried by the robot 1.

[0152] The invention thus makes it possible to obtain an autonomous robotic system for measuring radioactive contamination of roads, capable of locating itself and moving in its environment using LIDAR and GPS systems. The radioactive contamination measurements are carried out using gamma detectors (probe 4) sufficiently far from the ground, which makes it possible to resolve problems linked to meteorology, the condition of the surface and the fragility of the detectors. When contamination points are detected by the robot, they are automatically reported on the GPS map of the site (1002 mapping). The robot can have several operating modes: manual (use of a joystick), semi-automatic (setting up virtual barriers) and autonomous (automatic programming).

[0153] In the example described above, robot 1 makes it possible to detect the presence of a point source of 800 Bq of cobalt 60 on the surface.

[0154] The invention makes it possible to overcome another drawback of known devices, which is their fragility and lack of robustness, which generate significant maintenance costs.

[0155] The invention makes it possible to carry out inspections of horizontal surfaces, but also of walls or roofs, for example in the context of dismantling sites for nuclear power plants producing electricity, and makes it possible to carry out mapping of areas which are difficult and / or dangerous to access.

[0156] The invention can be implemented by all operators of nuclear installations requiring the carrying out of road inspections or inspections of interior surfaces not sectorized by the nature of their activity. The invention can be implemented by operators carrying out road inspections aimed at determining the presence of radioactive contamination.

[0157] Of course, the embodiments, features, possibilities and examples described above can be combined with each other or selected independently of each other.

Claims

Claims

1. 1. Autonomous robot (1) for detecting radiological contamination emanating from a surface (S), the robot (1) comprising: a system (2) for moving the robot (1) along the surface (S) or on the surface (S), a system (3) for providing a position (P) of the robot (1) relative to the surface (S) during a measurement, at least one gamma radiation detection probe (4), which comprises a gamma radiation detection diameter (Diam) against the surface (S) and which is capable of measuring detected hits in the detection diameter (Diam) in response to the gamma radiation, a wireless transceiver (5), a computer (6) for controlling the robot (1), configured to carry out the following steps: prescribing (EO, El, E2, E3, E8) a speed (V) of movement of the system (2) for moving the robot (1) and a duration (F;, Fi+i) of measurement of the probe (4) for detecting gamma radiation, controlling (E4) the system (2) for moving the robot (1) along a first path (Ti) at the prescribed speed (V) forward along the surface (S) or on the surface (S) and controlling the probe (4) to measure a first number (M) of counts detected in the detection diameter (Diam) during the prescribed duration (F;, Fi+i) of measurement during the first path (TJ, calculating (E4) a gamma radiation emission activity (A) as a function of the first number (M) of counts detected by the probe (4), comparing (E5) the gamma radiation emission activity (A) to a prescribed activity threshold (SA), for in the case where the gamma radiation emission activity (A) is lower than the prescribed activity threshold (SA), controlling the wireless transceiver (5) so that the wireless transceiver (5) transmits (E6) a first piece of information (INF1) indicating the absence of detection of radiological contamination, in the case where the gamma radiation emission activity (A) is greater than or equal to the prescribed activity threshold (SA), controlling the wireless transceiver (5) so that the wireless transceiver (5) transmits (E7) a second piece of information (INF2) indicating the detection of radiological contamination.

2. 2. Autonomous robot (1) according to claim 1, characterized in that the control computer (6) of the robot (1) is configured to, at each iteration of a first loop (Bi): during a first step (El), controlling the movement system (2) to move the robot (1) along at least a second path (T2) at the prescribed speed (V) forward along the surface (S) or on the surface (S) and controlling the probe (4) to measure a second number b; of detected strokes in the detection diameter (Diam) during the prescribed measurement time F; during the second path (T2), during a second step (E2), calculate a minimum detectable SDMC activity of gamma radiation emission, proportional to , during the prescribed measurement duration F;, T in a third step (E3), compare the minimum detectable SDMC gamma radiation emission activity to the prescribed activity threshold SA, for in the case where the minimum detectable gamma radiation emission activity SDMC is less than the prescribed activity threshold SA: at each iteration of a second loop (B2), during a fourth step (E4), controlling the movement system (2) to move the robot (1) along the first path (Ti) at the prescribed speed (V) forward along the surface (S) or on the surface (S), controlling the probe (4) to measure the first number M of detected counts in the detection diameter (Diam) during the prescribed measurement time (Fi) during the first path (Ti) and calculating the gamma radiation emission activity (A = (M-bi).SCR) as being proportional to the first number M of detected counts, from which the second number b; of detected counts is subtracted, during a fifth step (E5), compare the gamma radiation emission activity (A) to the prescribed activity threshold SA, for in the case where the gamma radiation emission activity (A) is lower than the prescribed activity threshold SA, controlling the wireless transceiver (5) so that the wireless transceiver (5) transmits the first information (INF1) indicating the absence of detection of radiological contamination by the wireless transceiver (5) during a sixth step (E6) and returning to the fourth step (E4) to carry out a following iteration of the second loop (B2), in the case where the gamma radiation emission activity (A) is greater than or equal to the prescribed activity threshold SA, controlling the wireless transceiver (5) so that the wireless transceiver (5) transmits the second information (INF2) indicating the detection of radiological contamination during a seventh step (E7), in the case where the minimum detectable gamma radiation emission activity SDMC is greater than or equal to the prescribed activity threshold SA: during an eighth step (E8) modifying the prescribed duration F;of measurement in a prescribed measurement time Fi+i modified according to „ _ SDMC-Fj , modify the prescribed speed (V) of the second path (T2) ri+l“ SA of the robot (1), corresponding to the prescribed measurement time Fi+i modified, along the surface (S) or on the surface (S) in a prescribed speed V2 modified according to y^ — 1¾¾¾ , where Diam is the detection diameter, then return to the first step (El) to carry out a next iteration of the first loop (B i) according to the prescribed measurement time Fi+i modified and according to the prescribed speed V2 modified.;

3. 3. Autonomous robot (1) according to claim 2, characterized in that the second path (T2) is initialized at a prescribed zone (ZO) of absence of radiological contamination of the surface (S) having a prescribed initial position (PO) against the surface (S) during a first iteration of the first loop (B i).

4. 4. Autonomous robot (1) according to claim 2 or 3, characterized in that the first information (INF1) further contains the gamma radiation emission activity (A) having been calculated and / or an uncertainty u(A) on the gamma radiation emission activity (A) according to u(A) = •

5. 5. Autonomous robot (1) according to any one of claims 2 to 4, characterized in that the minimum detectable SDMC activity is calculated according to d-JF-SA, where d is a determined index of sensitivity of the probe (4), SCR is a determined conversion factor of the probe (4) into number of counts per SA activity threshold.

6. 6. Autonomous robot (1) according to any one of claims 2 to 5, characterized in that the activity threshold SA is greater than or equal to 200 Bq and is less than or equal to 2000 Bq.

7. 7. Autonomous robot (1) according to any one of claims 2 to 6, characterized in that the computer (6) for controlling the robot (1) is configured to, following the seventh step (E7): during a ninth step (E9), control the movement system (2) to move and then immobilize the robot (1) in a fixed position (PF) located a prescribed length (L) greater than or equal to at least one first path (Ti) backward against the surface (S), during a tenth step (E10), control the probe (4) immobilized in the fixed position (PF) to measure N numbers rO[j] of detected strokes during N successive prescribed time windows Fj of measurement of equal durations D, where N is a determined natural integer, greater than or equal to 2, and j is a natural integer ranging from 1 to N, during an eleventh step (Eli), calculate an average rO of the N numbers rO[j] of detected hits, during a twelfth step (E12),calculate a measurement duration tg of the probe (4) as a function of the average rO, the threshold SA, N and D, and modify the speed (V) of movement of the system (2) of movement of the robot (1) to a prescribed speed V3 modified according to •,

8. 8. Autonomous robot (1) according to claim 7, characterized in that the computer (6) for controlling the robot (1) is configured to, following the twelfth step (E12), at each iteration of a third loop (B3): during a thirteenth step (El3), control the movement system (2) to move the robot (1) along a third path (T3) at the modified prescribed speed V3 forward along the surface (S) or on the surface (S) and control the probe (4) to measure a third number rg of detected counts in the detection diameter (Diam) during the prescribed measurement time tg during the third path (T3), during a fourteenth step (E14), calculate a running average rg' of the third number rg of detected counts during the prescribed measurement time tg, and calculate a modified gamma radiation emission activity (A') as being proportional to the moving average rg', from which the average rO is subtracted.

9. 9. Autonomous robot (1) according to claim 7 or 8, characterized in that that the duration D is less than or equal to the duration F; or to the duration Fi+i.

10. 10. Autonomous robot (1) according to any one of claims 7 to 9, characterized in that the modified prescribed speed V3 is lower than the modified prescribed speed V2.

11. 11. Autonomous robot (1) according to any one of claims 7 to 10, characterized in that m ----where k is a prescribed parameter, f SA V 1 [ \ k / "NB J

12. 12. Autonomous robot (1) according to any one of claims 8 to 11, when it depends at least on claim 8, characterized in that the computer (6) for controlling the robot (1) is configured to, following the fourteenth step (El4): during a fifteenth step (E15), compare the modified gamma radiation emission activity (A') with the prescribed activity threshold (SA), for in the case where the modified gamma radiation emission activity (A') is lower than the prescribed activity threshold (SA), control the wireless transceiver (5) so that the wireless transceiver (5) transmits during a sixteenth step (El6) a third information item (INF3) containing the modified gamma radiation emission activity (A') and / or an uncertainty (u(A')) on the modified gamma radiation emission activity (A'), in the case where the activity (A') modified gamma radiation emission is greater than or equal to the prescribed threshold (SA) of activity,controlling the wireless transceiver (5) so that the wireless transceiver (5) transmits during a seventeenth step (E17) a fourth information item (INF4), indicating the detection of radiological contamination and containing the modified gamma radiation emission activity (A') and / or an uncertainty (u(A')) on the modified gamma radiation emission activity (A').,

13. 13. Autonomous robot (1) according to claim 12, characterized in that the computer (6) for controlling the robot (1) is configured to, following the sixteenth step (E16) and following the seventeenth step (E17): during an eighteenth step (El8), determine whether the position (P) corresponds to a measurement already carried out during the at least one first path (TJ, for: in the case where the position (P) corresponds to the measurement by the at least one first path (TJ, return to the thirteenth step (E13) to carry out a following iteration of the third loop (B3), in the case where the position (P) does not correspond to the measurement by the at least one first path (Ti), return to the first step (El) to carry out a following iteration of a fourth loop (B4).

14. 14. Autonomous robot (1) according to any one of the preceding claims, characterized in that the gamma radiation detection probe (4) is located at a prescribed distance of at least 5 cm above a contact surface (20) of the movement system (2) with the surface (S).

15. 15. Autonomous robot (1) according to any one of the preceding claims, characterized in that the control computer (6) comprises a memory (61) and is configured to record the measurement (M, b,,, rO[j], rg, rg') and / or the gamma radiation emission activity (A, A') and / or the first information (INF1) or the second information (INF2) and / or the third information (INF3) or the fourth information (INF4) in association with the position (P), having been determined by the position supply system (3) during the measurement (M, b;,, rO[j], rg, rg').

16. 16. Method for detecting radiological contamination emanating from a surface (S) using the autonomous robot (1) according to any one of the preceding claims, characterized in that the method comprises said steps, implemented by the computer (6) controlling the robot (1).

17. 17. Computer program, comprising code instructions for implementing the method for detecting radiological contamination emanating from a surface (S) according to claim 16, when the program is executed on a computer (6).

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