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: Surface radiological contamination detection robot, 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 relates to metrology in radiation protection, in particular for the control of soil and road contamination, in order to determine the presence or absence of artificial radioactivity.

[0003] Current regulations require periodic inspections of roads likely to be used by radioactively contaminated material. These road inspections must ensure that radioactive contamination does not disperse outside the site and into the soil (regulatory requirement).

[0004] One area of ​​application concerns, in particular, nuclear power plants. Within these plants, basic nuclear installations (INB) and classified installations for environmental protection (ICPE) define a traffic plan for means of transport carrying hazardous materials on their site. The roads affected by the movement of radioactive materials are those that will be subject to annual road inspections.Certain areas are subject to more frequent inspections, including the section of roadway beneath various buildings of a nuclear power plant (abbreviated as: BR (Reactor Building), BK (Fuel Building), BAN (Nuclear Auxiliary Building), BW (Operations Building), BTE (Effluent Treatment Building), the areas in front of the exit airlocks of the ZppDN zones (abbreviation for: zone with potential nuclear waste production) of the BK, BAN, BW, BTE buildings, the washing plant, the hot workshop, the transport control building, and the areas near the storage areas. The frequency of inspections is adjusted according to the type of outage, the volume, and the type of activities. Furthermore, it is mandatory to carry out non-contamination checks in the areas adjacent to the ZppDN exit airlocks (airlocks designated by the ex-DI82 designation) used following the internal transfer of oversized equipment such as TN12 (fuel removal). worn). .

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

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

[0007] These devices also have the disadvantage of requiring the device to maintain a small distance between its beta radiation detector and the ground, or even to be in near contact with the ground. This necessitates monitoring by the person using the device and presents a risk of damage to the beta radiation detector if the device passes over a surface with protrusions, due, for example, to the presence of objects or materials on the ground or road surface, or to surface deterioration. These devices are therefore fragile and lack robustness, resulting in 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 proves 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, and a computer program for implementing the method, which overcome the disadvantages 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 the robot's position relative to the surface during a measurement, at least one gamma radiation detection probe, which includes a gamma radiation detection diameter against the surface and which is capable of measuring impacts detected in the detection diameter in response to gamma radiation, a wireless transceiver, a robot control computer, configured to perform the following steps: prescribe a speed for the robot's movement system and a measurement duration for the gamma radiation detection probe, command the movement system to move the robot along a first path at the prescribed speed forward along or across the surface and command the probe to measure a first number of impacts detected within the detection diameter during the prescribed measurement time during the first path, calculate a gamma radiation emission activity as a function of the first number of impacts detected by the probe, compare the gamma radiation emission activity to a prescribed activity threshold, for in the event that the gamma radiation emission activity is below the prescribed activity threshold, command the wireless transceiver to transmit a first message indicating the absence of detection of radiological contamination, in the event that the gamma radiation emission activity is greater than or equal to the prescribed activity threshold, command the wireless transceiver to transmit a second message indicating the detection of radiological contamination.

[0011] The invention makes it possible to perform surface checks for radiological contamination, such as on potentially polluted soil or roads in a nuclear power plant. Thanks to the invention, gamma radiological contamination emitted by a radionuclide at, or below, the surface can be quickly detected.

[0012] One advantage of the invention is that it eliminates the need for measurements based on the surface condition, for example, of the ground or road surface. Dust or the roughness of the road surface is no longer a constraint, since the measurement involves gamma radiation. Similarly, weather conditions, particularly the presence of soil moisture, are no longer considered problematic and likely to distort the measurement. Furthermore, certain radionuclides that do not emit beta particles, but alpha particles as well as gamma radiation, can be detected. The method therefore extends the detection range. Gamma radiation can penetrate materials, making it possible to measure surface radioactivity even if the surface is wet. This increases the overall availability of the measuring device and allows road inspections to be carried out as close as possible to the point of need.

[0013] The invention eliminates the need to maintain a small distance between the gamma radiation detection probe and the surface and offers the advantages of high robustness and low maintenance and personnel costs. Gamma radiation can be detected at a greater distance than beta radiation (penetration into matter), meaning that it is not necessary to place the gamma radiation detection probe in close contact with the surface or ground. This reduces the risk of the gamma radiation detection probe coming into contact with road defects or objects and materials present on the road surface.

[0014] The invention makes it possible to avoid monopolizing a person who has to 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 the first step, control the movement system to move the robot, following at least a second path at the prescribed speed forward along or across the surface, commands the probe to perform a second measurement of b; of impacts detected within the detection diameter during the prescribed duration F; of measurement during the second path, In a second step, calculate a minimum detectable SDMC activity of gamma radiation emission, proportional to , for the prescribed duration F i of measurement, In a third step, compare the minimum detectable SDMC activity of gamma radiation emission to the prescribed SA activity threshold, in the case where the minimum detectable SDMC activity of gamma radiation emission is lower than the prescribed SA activity threshold: At each iteration of a second loop, during a fourth step, command the movement system to move the robot along the first path at the prescribed speed forward along or across the surface, command the probe to measure the first number M of detected hits in the detection diameter during the prescribed measurement time during the first path, and calculate the gamma radiation emission activity as being proportional to the first number M of detected hits, minus the second number b of detected hits. In a fifth step, compare the gamma radiation emission activity to the prescribed SA activity threshold, for In the event that the gamma radiation emission activity is below the prescribed SA activity threshold, command the wireless transceiver to transmit the first information indicating the absence of detection of radiological contamination by the wireless transceiver during a sixth step and return to the fourth step to perform a subsequent iteration of the second loop, In the event that the gamma radiation emission activity is greater than or equal to the prescribed SA activity threshold, command the wireless transceiver to transmit the second information indicating the detection of radiological contamination during a seventh step, in the event that the minimum detectable SDMC gamma radiation emission activity is greater than or equal to the prescribed SA activity threshold: during an eighth step, modify the prescribed measurement time F; to a modified measurement time Fi+i according to p _ SDMCF, , modify the prescribed speed of the second robot journey, corresponding to the prescribed modified measurement time Fi+i, 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 prescribed duration Fi+i of modified measurement and according to the prescribed speed V2 modified.

[0016] According to one embodiment of the invention, the second path is initialized to 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 one embodiment of the invention, the first piece of information further contains the calculated gamma radiation emission activity 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 specific index of probe sensitivity. SCR is a conversion factor determined from the probe to the number of counts per SA activity threshold.

[0019] According to one embodiment of the invention, the SA activity threshold 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: In a ninth step, command the movement system to move and then immobilize the robot in a fixed position located at a prescribed length greater than or equal to at least one first backward path against the surface, In a tenth step, command the probe, immobilized in the fixed position, to perform the measurement of N numbers rO[j] of detected hits during N successive prescribed time windows Fj of measurement of equal durations D, where N is a determined natural number, greater than or equal to 2, and j is a natural number from 1 to N, In an eleventh step, calculate a mean rO of the N numbers rO[j] of detected hits, in a twelfth step, calculate a measurement time tg of the probe as a function of the mean rO, the threshold SA, N and D, and modify the speed of movement of the robot movement system to a prescribed speed V3 modified 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, command the movement system to move the robot along a third path at the modified prescribed speed V3 forward along or on the surface and command the probe to perform the measurement of a third number rg of detected hits in the detection diameter during the prescribed measurement time tg during the third path, in a fourteenth step, calculate a moving average rg' of the third number rg of detected hits during the prescribed measurement time tg, and calculate a modified gamma radiation emission activity as being proportional to the moving average rg', from which is subtracted the mean rO.

[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 less 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 to the prescribed activity threshold, for In the event that the modified gamma radiation emission activity is below the prescribed activity threshold, command the wireless transceiver to transmit, during a sixteenth step, a third piece of information containing the modified gamma radiation emission activity and / or an uncertainty about the modified gamma radiation emission activity. in the event that the modified gamma radiation emission activity is greater than or equal to the prescribed activity threshold, command the wireless transceiver to transmit during a seventeenth step a fourth piece of 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: In an eighteenth step, determine if the position corresponds to a measurement already taken during at least one previous journey, for: in the case where the position corresponds to the measurement by at least one first path, return to the thirteenth step to perform the next iteration of the third loop, in the case where the position does not correspond to the measurement by at least one first path, return to the first step to perform a subsequent 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 includes a memory and is configured to record the measurement and / or gamma radiation emission activity and / or the first piece of information or the second piece of information and / or the third piece of information or the fourth piece of 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 object of the invention is a computer program, comprising code instructions for implementing the method of 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 upon reading the following description, given solely by way of non-limiting example with reference to the figures below of the attached drawings.

[0032] [Fig-1] represents a schematic front perspective 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 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, following on from B in [Fig.4A]. [Fig.4B] continues from C in [Fig.4A].

[0037] An example of an autonomous robot for detecting radiological contamination is described in more detail below with reference to [Fig.1].

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

[0039] The autonomous robot 1 includes a system 2 for moving the robot 1 along or on the surface S. This system includes, for example, at least three or four wheels 21, 22, 23, 24 rolling against the surface S (arranged in a quadrilateral in top view) and means for keeping 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 mounted to rotate 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 backward direction X2 of the longitudinal direction X relative to the surface S.Figures 1 and 2 also show the Z direction 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 Y1 direction to the left of the transverse direction Y and the Y2 direction to the right of the transverse direction Y. At least one or more of the wheels 21, 22, 23, 24, such as wheel 21, is steerable and is able to be turned to the left in the direction Y1 and to the right in the direction Y2 with respect 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 includes, 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 with respect to the surface S during a measurement.

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

[0042] The position supply system 3 P may include, 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 includes, attached to the chassis 25, one (or more) gamma radiation detection probe(s) 4. Figure 3 shows a path T of the same probe 4 during the movement of the robot 1 against the surface S, from a position P1 to a position P2; the rest of the robot 1 is not shown. Each probe 4 has a non-zero diameter Diam for detecting gamma radiation against the surface S (the scanned area ZD formed by the circle of diameter Diam on the surface S). Each probe 4 is capable of measuring impacts detected in response to the gamma radiation emitted by the surface S within 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 non-zero height h0 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 detection diameter Diam and allows the capture of gamma radiation emitted from the scanned zone ZD of the surface S and directed within the detection cone 40 towards the center 42 of the receiver 41. The gamma radiation detection probe(s) 4 can be positioned at the front of the robot 1. The probe 4 can be covered on top by a sealing cap and hermetically sealed (especially against moisture) in a protective housing.For example, two gamma radiation detection probes 4 can be provided, located side by side along the transverse direction Y. The movement system 2 allows the robot 1 to scan the surface S in successive positions at least along 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 can be located at the prescribed height hO, at least 5 cm above a contact surface 20 of the movement system 2 with the surface S. The height hO can be greater than or equal to 5 cm and less than or equal to 20 cm. In particular, the height hO can be greater than or equal to 10 cm. For example, the height hO can be approximately 15 cm. The diameter of the wheels 21, 22, 23, 24 can 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 can be 30 cm.

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

[0046] The gamma radiation detection probe(s) 4 may be a scintillation probe or scintillator. 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 Nal(Tl) (thallium-doped sodium iodide). In another example, the inorganic scintillator may comprise a measuring material containing CsI(Tl) (thallium-doped cesium iodide). In yet 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, where provided, also the minimum detectable SDMC gamma radiation emission activity during step E1) can be performed for a specified radionuclide of interest, emitting gamma radiation from the surface S. The SA threshold may have been prescribed for this specified 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, distinguish them, and perform a measurement of the number of detected hits (b; and, where provided, also M) for a specified radionuclide of interest or for each of several specified radionuclides of interest. For example, a specified radionuclide of interest might be 60Co. Another specified radionuclide of interest might be 137Cs.

[0048] The measurement of the gamma radiation emission activity A during step E4 (and, where applicable, also the minimum detectable SDMC gamma radiation emission activity during step El) can be calibrated for a specific radionuclide of interest, referred to as the reference radionuclide. This specific reference radionuclide of interest could be, for example, 60Co. To perform this calibration, a known quantity of the specific reference radionuclide of interest is placed in the surface at a known location, and the robot 1 performs measurements at this location. The values ​​of the gamma radiation emission activity A (and, where applicable, also the minimum detectable SDMC gamma radiation emission activity during step El) are then calculated to obtain prescribed values ​​based on the known quantity of the specific reference radionuclide of interest.

[0049] The conversion SCR factor, described below, allows the gamma radiation emission activity A for a given radionuclide of interest, other than the reference radionuclide of interest, to be calculated from the first number M of detected counts. The conversion SCR factor is determined and / or prescribed and / or pre-established. recorded in memory 61 of the computer 6. The SCR conversion factor varies depending on the probe 4.

[0050] The overall conversion factor K, described below, allows the minimum detectable SDMC activity of gamma radiation emission for a given radionuclide of interest, other than the reference radionuclide of interest, to be calculated, when specified. This is based on the second number of detected counts. The overall conversion factor K is determined and / or prescribed and / or pre-recorded in memory 61 of the computer 6.

[0051] The autonomous robot 1 includes, fixed to the chassis 25, a wireless transceiver 5 (having a transmitting-receiving antenna 51), allowing it to send information to a remote station 1000 and to receive information from the remote station 1000. A detection device may include the autonomous robot 1 and the remote station 1000.

[0052] The autonomous robot 1 includes, attached to the chassis 25, a robot 1 control computer 6. The control computer 6 is configured to perform the steps described below, with reference to Figures 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 robot 1 control computer 6, with reference to Figures 4A and 4B. The control computer 6 may be or include one or more computers, one or more processors, one or more microprocessors, one or more control circuits, or other components. The control computer 6 may have been programmed by a computer program, including code instructions for implementing the method, when implemented on this computer, with reference to Figures 4A and 4B.

[0053] A first embodiment of certain steps is described below. The first embodiment allows for the detection of 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 robot 1 movement system 2 and a duration F; or Fi+i of measurement of the gamma radiation detection probe 4.

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

[0056] Then, during step E4, the computer 6 commands 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 or on the surface S. The computer 6 commands the probe 4 to perform the measurement of a first number M of strokes detected in the diameter Diam of detection during the prescribed time F; or Fi+i of measurement during the first path Th The robot 1 position supply system 3 provides different positions P of robot 1 and probe 4 along the first path Th

[0057] During step E4, computer 6 calculates an activity A of gamma radiation emission as a function of the first number M of hits detected by 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 radiological contamination detection threshold. The prescribed activity threshold SA determines, in steps E5, E6, and E7, whether the scanned area ZD of the surface S at position P is contaminated or not.

[0059] In the event that (YES at step E5), at step E5, the computer 6 determines that the gamma radiation emission activity A is below the prescribed activity threshold SA, i.e., A < SA, the computer 6 commands the wireless transceiver 5 to transmit, during step E6, a first INF1 signal 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 position P and measured by the probe 4.

[0060] In the event that (NOT at step E5), at 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., A > SA, the computer 6 commands the wireless transceiver 5 to transmit, during step E7, a second INF2 signal indicating the detection of radiological contamination. The second INF2 signal may contain an AL alarm. The SA threshold is a real number expressed in Bq (Becquerels) or s1. The gamma radiation emission activity A is a real number expressed in Bq (Becquerels) or s1. During step E7, the computer 6 commands 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 (or ionizing or radioactive) contamination is present locally at position P on surface S, without requiring a person to be present at that location. The first embodiment also allows the user to be notified if this radiological contamination is detected by sending the INF2 information remotely.

[0062] For each measurement of the number M performed by the probe P and / or for each gamma radiation emission activity A calculated by the computer 6, the position P, determined by the position P supply system 3 of the robot 1, can be associated or recorded in memory 61 of computer 6 with the measurement of the number M and / or with the gamma radiation emission activity A calculated by computer 6 and / or with the first piece of information INF1 or with the second piece of information INF2. Robot 1 thus maps the surface S by passing successively through several positions P along or on the surface S. Robot 1 thus calculates the gamma radiation emission activity A for each position P through which robot 1 passes.

[0063] A second embodiment of certain additional steps compared to the first embodiment is described below. The second embodiment allows for the removal of a measure b, taking into account background noise.

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

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

[0066] The second path T2 can be initialized to a prescribed zone Z0 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 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 time F. This minimum detectable SDMC activity of gamma radiation emission is proportional to . The computer 6 calculates the activity minimum detectable SDMC gamma radiation emission, as being 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 calculator 6.

[0070] For example, 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 memory 61 of computer 6) of the sensitivity of probe 4 to gamma radiation and is a dimensionless real number, es is an efficiency of probe 4 (efficiency of the measuring instrument) determined (and / or pre-recorded in memory 61 of computer 6), SCR is the conversion factor to strokes per SA threshold.

[0073] So in this example we have:

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

[0076] s^d'-Tb"

[0077] Then, the calculator 6 can calculate a minimum MDCRS count rate, 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 SA activity threshold may be greater than or equal to 15 Bq and less than or equal to 2000 Bq. For example, the SA activity threshold may be equal to 800 Bq.

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

[0083] For example, in embodiments of the invention, the efficiency es of the probe 4 can 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 can 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 SA activity threshold and less than or equal to 10,000 counts per SA activity threshold. For example, the SCR conversion factor may be equal to 10 counts per SA activity threshold, and for example, to 10 counts per 800 Bq. The value of 800 Bq may correspond to the presence of an 800 Bq point source of cobalt-60 on the surface S, referred to as the reference radionuclide. Of course, the reference radionuclide could be something other than cobalt-60.

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

[0086] In the case (YES at step E3) where, during the third step E3, the calculator 6 determines that the minimum detectable SDMC gamma radiation emission activity 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, commands the movement system 2 to move the robot 1 along the first path Ti (or scan) at the prescribed speed V forward along or across the surface S, commands the probe 4 to measure the first number M of detected hits in the detection diameter Diam during the prescribed measurement time F; during the first path Ti, and calculates the gamma radiation emission activity A as being proportional to the first number M of hits detected during the measurement, from which is subtracted the second number b; of hits detected during background acquisition, according

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

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

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

[0090] In the case where (NOT at step E5), at 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. A > SA, the computer 6 commands the wireless transceiver 5 to transmit during the seventh step E7 described above the second information INF2 indicating the detection of radiological contamination.

[0091] In the case where (NOT at step E3), at the third step E3, the computer 6 determines that the minimum detectable SDMC activity of gamma radiation emission is greater than or equal to the prescribed activity threshold SA, i.e., SDMC > SA, the computer 6, during an eighth step E8, modifies the prescribed measurement time F to a modified prescribed measurement time 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 or on the surface S into a modified prescribed speed V2 according to

[0094] y - Dhjm 2 Fkl

[0095] This modified prescribed velocity V2 corresponds to the path traversed by the second path T2 along the surface S, or on the surface S in the forward direction XI, during the modified prescribed measurement time Fi+i. Then, after step E8, the computer 6 returns to the first step El to perform a subsequent iteration of the first loop Bi, using the modified prescribed measurement time Fi+i instead of the prescribed measurement time F, and using the modified prescribed velocity V2 instead of the prescribed velocity V in this subsequent iteration of the first step El. The following iteration(s) allow the calculation of the modified prescribed velocity V2 such that the minimum detectable SDMC activity of gamma radiation emission is less than the prescribed activity threshold SA, i.e., SDMC < SA.

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

[0097] The minimum detectable SDMC activity of gamma radiation emission is determined from the minimum count MDCRS by applying the SCR conversion factor, which takes into account the size of the Nal(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 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 scan of step E1 or E4 is the actual time during which the detector of probe 4 can respond to the contamination source on 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 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 error. Risks are reduced by controlling the speed V2 according to the background noise. This leads to better accuracy, reproducibility, and reliability in the execution of road inspections.

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

[0101] In the preceding, during the sixth step E6, the first piece of information INF1 may further contain the calculated gamma radiation emission activity A 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 or second embodiment is described below. The third embodiment allows for a more precise calculation of a gamma radiation emission activity A' and for validating or invalidating the second piece of information INF2 indicating the detection of radiological contamination. The third embodiment of the invention is performed by the robot 1 control computer 6 following the seventh step E7.

[0104] According to the third embodiment of the invention, following the seventh step E7, the computer 6 commands 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 the first paths TJ backwards in the direction X2 against the surface S). The computer 6 commands the movement system 2 to immobilize the robot in this fixed position PF.

[0105] Then, during a tenth step E10, the computer 6 commands the probe 4, immobilized in the fixed position PF, to measure N numbers rO[j] of detected strikes during N successive prescribed time windows Fj of equal durations D. N is a specific natural number, greater than or equal to 2, and j is a natural number 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 computer 6 calculates an average rO of the N numbers rO[j] of detected hits. 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 time tg for 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 the robot 1's movement system 2 to 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 El and / or E4.

[0111] During the twelfth step El2, the computer 6 can calculate the measurement time 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 robot 1 therefore adapts the speed V3 in order to comply with the above condition on SA.

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

[0117]

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

[0119] 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 commands the movement system 2 to move the robot 1 along a third path T3 at the modified prescribed speed V3 forward along or on the surface S. During the thirteenth step E13 of the third loop B3, the computer 6 commands the probe 4 to measure a third number rg of detected impacts in the detection diameter Diam during the prescribed measurement time tg during the third path T3. The robot 1 position supply system 3 provides different positions P of the robot 1 and of 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 moving average rg' of the third number rg of detected hits during the prescribed measurement time tg, that is rg'=rg / tg.

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

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

[0124] The modified gamma radiation emission activity A' is a real number 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 to be 6 seconds in this example.

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

[0128] 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 event that, at the fifteenth step E15, the computer 6 has determined that the modified gamma radiation emission activity A' is below the prescribed activity threshold SA, the computer 6 commands the wireless transceiver 5 to transmit, during a sixteenth step E16 of the third loop B3, a third piece of information INF3 containing the modified gamma radiation emission activity A' and / or an uncertainty u(A') on the modified gamma radiation emission activity A'.

[0131] If, at 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 commands the wireless transceiver 5 to transmit, during a seventeenth step E17 of the third loop B3, a fourth INF4 message 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 INF4 message may contain an AL alarm.

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

[0133] The calculator 6, following the sixteenth step E16 and following the seventeenth step E17, to Each iteration of a third loop B3 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 at least one first path Ti, i.e. whether the current position P, provided by the robot 1 position supply system 3 for the measurement step E13, is in a range of positions P where a measurement of the first number M of detected hits 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 at step E18), that the current position P of the step E13 corresponds to a measurement by at least one first path Tb the computer 6 returns to the thirteenth step E13 to perform a subsequent 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 (NOT at step E18), that the current position P of step E13 does not correspond to a measurement by at least one first path Tb of the computer 6 returns to the first step El to perform a next 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

[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 memory 61 of the control computer 6 can be recorded the measurement M, b, 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, b, rO[j], rg, rg' and / or the AL alarm.

[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 include an information presentation means 1001 for displaying to a user the measurement M, b, rO[j], rg, rg' and / or the gamma radiation emission activity A, A' and / or the first piece of information INF1 or the second piece of information INF2 and / or the third piece of information INF3 or the fourth piece of information INF4 in association with the position P, having been determined by the position provisioning system 3 during the measurement M, b, rO[j], rg, rg', and / or the AL alarm, 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 include a display screen. Information presentation method 1001 can display on screen a specific visual indication or icon of absence of radiological contamination (e.g. a green tile) associated with the INF1 and / or INF3 information.Information presentation method 1001 can display on the screen a specific visual indication or icon of the presence of radiological contamination (e.g., a red tile) associated with the INF2 and / or INF4 information. Remote station 1000 can be a portable device, such as a computer, tablet, or phone. Remote station 1000 can... include control means for remotely controlling the robot 1. The remote station 1000 may include a memory 1003 to store the measurement M, b,, 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, for example on a map 1002 of the surface S, or more generally to store the values ​​recorded in the memory 61 of the computer 6.

[0144] Step E10 of the third embodiment of the invention allows for the measurement of background noise, formed by the number rO[j] of detected hits. The measurement of the gamma radiation emission activity A' is thus rendered relatively insensitive to background noise.

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

[0146] The third embodiment of the invention reduces human error. Risks are reduced by controlling the speed V3 according to the background noise. This leads to improved accuracy, reproducibility, and reliability in the execution of road inspections.

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

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

[0149] The robot 1 may have on the chassis 25 one or more auxiliary connectors 29, in order to be able to connect additional sensors, which must be carried by the chassis 25.

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

[0151] The robot 1 includes in the chassis 25 a power supply battery, enabling the computer 6, the sensor 4, the systems 2 and 3, the wireless transceiver (5) and the elements carried by the robot 1 to be powered.

[0152] The invention thus provides an autonomous robotic system for measuring radioactive contamination of roads, capable of locating itself and moving within its environment using LIDAR and GPS systems. Radioactive contamination measurements are carried out using gamma detectors (probe 4) sufficiently far from the ground, which makes it possible to resolve problems related to meteorology, to The condition of the surface and the fragility of the detectors are taken into account. When contamination points are detected by the robot, they are automatically recorded on the site's GPS map (1002 mapping). The robot can operate in several modes: manual (using 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 disadvantage of known devices, which is their fragility and lack of robustness, which generates significant maintenance costs.

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

[0156] The invention can be implemented by all operators of nuclear facilities requiring the performance of inspections of roads or indoor surfaces not restricted by the nature of their activity. The invention can be implemented by operators carrying out inspections of roads to determine 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

Demands

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 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 has a gamma radiation detection diameter (Diam) against the surface (S) and which is capable of measuring impacts detected in the detection diameter (Diam) in response to gamma radiation, a wireless transceiver (5), a computer (6) for controlling the robot (1), configured to perform the following steps: prescribe (EO, E1, E2, E3, E8) a speed (V) of movement of the robot (1) movement system (2) and a measurement time (F1, F1+i) of the gamma radiation detection probe (4), command (E4) the movement system (2) to move the robot (1) along a first path (T1) at the prescribed speed (V) forward along or on the surface (S), and command the probe (4) to perform the measurement of a first number (M) of detected hits in the detection diameter (D1) during the prescribed measurement time (F1, F1+i) during the first path (T1, calculate (E4) a gamma radiation emission activity (A) as a function of the first number (M) of counts detected by the probe (4), compare (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 less than the prescribed activity threshold (SA), command the wireless transceiver (5) so that the wireless transceiver (5) transmits (E6) a first 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), command the wireless transceiver (5) so that the wireless transceiver (5) transmits (E7) a second information (INF2) indicating the detection of radiological contamination.

2. 2. Autonomous robot (1) according to claim 1, characterized in that the robot (1) control computer (6) is configured to, at each iteration of a first loop (Bi): in a first step (E1), command 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 command the probe (4) to perform the measurement of a second number b; of impacts detected in the detection diameter (Diam) during the prescribed measurement time F; during the second path (T2), In a second step (E2), calculate a minimum detectable SDMC activity of gamma radiation emission, proportional to , during the prescribed measurement time F; T in a third step (E3), compare the minimum detectable SDMC activity of gamma radiation emission to the prescribed SA activity threshold, for In the case where the minimum detectable SDMC gamma radiation emission activity is less than the prescribed SA activity threshold: at each iteration of a second loop (B2), during a fourth step (E4), command the displacement system (2) to move the robot (1) along the first path (Ti) at the prescribed speed (V) forward along or on the surface (S), command the probe (4) to measure the first number M of detected hits in the detection diameter (Diam) during the prescribed measurement time (Fi) during the first path (Ti), and calculate the gamma radiation emission activity (A = (M-bi).SCR) as being proportional to the first number M of detected hits, minus the second number b of detected hits. in a fifth step (E5), compare the gamma radiation emission activity (A) to the prescribed activity threshold SA, for in the event that the gamma radiation emission activity (A) is below the prescribed activity threshold SA, command the wireless transceiver (5) to transmit the first information (INF1) indicating the absence of detection of radiological contamination by the wireless transceiver (5) during a sixth step (E6) and return to the fourth step (E4) to perform a subsequent iteration of the second loop (B2), in the event that the gamma radiation emission activity (A) is greater than or equal to the prescribed activity threshold SA, command the wireless transceiver (5) to transmit the second information (INF2) indicating the detection of radiological contamination during a seventh step (E7), in the event that the minimum detectable SDMC gamma radiation emission activity is greater than or equal to the prescribed activity threshold SA: during an eighth step (E8) modify the prescribed duration F;of measurement in a prescribed time Fi+i of measurement 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 time Fi+i of modified measurement, along the surface (S) or on the surface (S) at a prescribed speed V2 modified according to y^ — 1¾¾¾ , where Diam is the detection diameter, then return to the first step (El) to perform a next iteration of the first loop (B i) according to the prescribed time Fi+i of modified measurement 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 to 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 piece of information (INF1) further contains the calculated gamma radiation emission activity (A) 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 sensitivity index of the probe (4), SCR is a determined conversion factor of the probe (4) into the number of counts per SA activity threshold.

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

7. 7. An autonomous robot (1) according to any one of claims 2 to 6, characterized in that the robot (1) control computer (6) is configured to, following the seventh step (E7): during a ninth step (E9), command 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 backward path (Ti) against the surface (S); during a tenth step (E10), command the probe (4) immobilized in the fixed position (PF) to perform the measurement of N numbers rO[j] of detected hits during N successive prescribed time windows Fj of measurement of equal durations D, where N is a determined natural number, greater than or equal to 2, and j is a natural number from 1 to N; during an eleventh step (E11), calculate an average rO of the N numbers rO[j] of detected hits, during a twelfth step (E12),calculate a measurement time 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 robot (1) control computer (6) is configured to, following the twelfth step (E12), at each iteration of a third loop (B3): during a thirteenth step (E13), command the movement system (2) to move the robot (1) along a third path (T3) at the modified prescribed speed V3 forward along or on the surface (S) and command the probe (4) to perform the measurement of a third number rg of detected hits in the detection diameter (Diam) during the prescribed measurement time tg during the third path (T3); during a fourteenth step (E14), calculate a moving average rg' of the third number rg of detected hits 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 less than the modified prescribed speed V2.

11. 11. An 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. An autonomous robot (1) according to any one of claims 8 to 11, where it depends at least on claim 8, characterized in that the robot (1) control computer (6) is configured to, following the fourteenth step (El4): during a fifteenth step (E15), compare the modified gamma radiation emission activity (A') to the prescribed activity threshold (SA), and, if the modified gamma radiation emission activity (A') is below the prescribed activity threshold (SA), command the wireless transceiver (5) to transmit, during a sixteenth step (El6), a third piece of information (INF3) containing the modified gamma radiation emission activity (A') and / or an uncertainty (u(A')) on the modified gamma radiation emission activity (A'), if the activity (A') modified gamma radiation emission is greater than or equal to the prescribed threshold (SA) of activity,command the wireless transceiver (5) so that the wireless transceiver (5) transmits during a seventeenth step (E17) a fourth piece 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').

13. 13. Autonomous robot (1) according to claim 12, characterized in that the robot (1) control computer (6) is configured to, following the sixteenth step (E16) and following the seventeenth step (E17): during an eighteenth step (E18), determine if the position (P) corresponds to a measurement already made during at least one first journey (TJ), so that: in the case where the position (P) corresponds to the measurement by the at least one first journey (TJ), return to the thirteenth step (E13) to perform a subsequent iteration of the third loop (B3), in the case where the position (P) does not correspond to the measurement by at least one first path (Ti), return to the first step (El) to perform a subsequent 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 piece of information (INF1) or the second piece of information (INF2) and / or the third piece of information (INF3) or the fourth piece of 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 of 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 of detecting radiological contamination emanating from a surface (S) according to claim 16, when the program is executed on a computer (6).