ES2550402B1 - Device for measuring activity and segregation of lands contaminated by 241Am - Google Patents

Abstract

Device for measuring activity and segregation of land contaminated by {IMAGE-01}, comprising: # - a support structure (17); # - a rotating element (12) that swings around the support structure in a position for filling (4), a measuring position (5) and a discharge position for contaminated material (6); # - a container of land (3) with the land to be analyzed, in solidarity with the rotating element (12); # - four Nal (TI) type FIDLER scintillation detectors (facing two to two), responsible for determining whether the lands contained in the container (3) are contaminated by {IMAGE-01}. # In the measurement position (5) The earth container (3) is located in the space between the four scintillation detectors (9) facing each other, the simultaneous measurement of the earth container (3) being performed, with the scintillation detectors (9) that are activated.

Description

DESCRIPTION

Device for measuring activity and segregation of lands contaminated by 241Am.

Field of the invention 5

The present invention falls within the field of soil treatment systems contaminated with 241Am and in particular is directed to the measurement of radioactivity and segregation of contaminated land.

 10

Background of the invention

Soils contaminated with transuranic are a serious environmental problem. Conventional technologies with potential to reduce risk, cost and volume of radiologically contaminated land, such as washing, flotation, bioremediation, magnetic separation, gravity separation and vitrification have been evaluated. These techniques are often expensive, being difficult to obtain reduction volumes above 70%.

In the last two decades, a new technology has been used for the remediation of contaminated land, based on the classification of soils by their concentration of activity. This technology known as Segmented Gate System (SGS), measures the radioactivity of the soil when it is being transported by a mechanized belt. Basically, the SGS system consists of a conveyor belt, and a matrix of thallium-activated sodium iodide scintillation detectors, NaI (Tl). The system uses 25 water to suppress dust generated during the land segregation process. The contaminated soil is loaded onto the conveyor belt, forming a thin layer not exceeding 5.08 cm, which passes under the detectors. When they detect radioactive material, the earth is diverted to a pile where the contaminated soil is deposited; the rest of the ground is directed towards a pile of "clean" soil. This system allows to treat the order of 26 30 m3h-1 of soil, with a density of 1.2 gcm-3.

The SGS system has been used in various locations, as described in the bibliographic references [1-5]. Compared to the systems referred to conventional technologies, the SGS system does not use chemical products and the generation of secondary waste (washing water and personal protective equipment) is minimal. However, one of the requirements of the SGS is that the land has to be homogeneously distributed in a thin layer on the conveyor belt; in this way detection limits of the order of 0.37 Bqg-1 of soil are reached.

 40

In US5,573,738 a method is described for use in the decontamination of materials such as soil, sludge, sediment, yard dust debris and the like, which are contaminated with radioactive materials such as 226Ra, 238U, or 238Th. The material is verified directly with a scanner, for example a sodium iodide detector. The measurement is carried out on a conveyor belt, where the material is spread 45 with a uniform thickness, preferably not more than 6 '(15.24 cm). The detectors preferably used are low radiation energy probes that operate in an energy range of about 13 to 24 keV. Subsequently, the elimination of uranium is carried out through a two-stage leaching process.

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In US5,045,240 a complex system is described that performs the treatment of large volumes of material, for example 9 Th-1. Makes an initial screening of the residue

radioactive (soils) and identifies the particle size range of the severely contaminated material fraction, processing said fraction. This fraction is subjected to a treatment to eliminate soluble compounds (radio, uranium, radioactive thorium and other radioactive species), by passing through a fluidized bed, which contains a leaching solution. The detection is done with a radioactivity scanner, for example 5 sodium iodide detectors, arranged on the sample to be measured, which in turn is placed on a conveyor belt.

The present invention provides significant improvements over the SGS system and other systems described above. On numerous occasions, especially when the emissions of the contaminated material that is inspected are low energy, the geometric arrangement of the material is essential. Defects in the arrangement of the latter, such as irregularities in the thickness of the layer that is placed on the conveyor belt may lead to erroneous measurements. The present invention works with a very well defined material geometry, which prevents this type of errors from occurring. fifteen

Another aspect that is of particular importance in the systems described above is that the segregation of the material is not carried out simultaneously to its measure, but that a certain time elapses between them. This forces the system to have a perfect temporal coordination between the performance of the activity measure and the separation mechanisms of the material. If for any reason this coordination is lost, there is a risk of mixing the streams of contaminated and uncontaminated materials.

The present invention avoids this type of situation, by arranging the material in discrete samples on which activity determinations are made. Thus, each of the samples is measured, kept separate from the rest of the material, and directed to the stream of contaminated or uncontaminated material, as appropriate.

Another important aspect of the present invention is the selection of FIDLER Field Instrument for Detection of Low Energy Radiation detectors and their arrangement around the 30 discrete samples that are inspected, which give the system an extremely sensitive measuring capacity in relatively short times.

Bibliographic references

 35

[1] C. A. Judd (1997). Maywood Chemical Company Superfund Site. Administrative record (1997). Document Number MISS- 106. 02/27/97.

http://www.fusrapmaywood.com/Docs/MISS-106.pdf.

[2] L. S. Hoeffner, J. D. Navratil, G. Torrao (2000). Evaluation of Remediation 40 Technologies for Plutonium Contaminated Soil. WM’02 Conference, February Tucson, AZ (US) 24-28 / 2002.

http://www.wmsym.org/archives/2002/Proceedings/12/435.pdf

[3] R. P. Wells (1999). Treatability Study (ts) Work Plan for Segmented Gate System 45 Technology Deployment. Document Number

INEEL / EXT-98-01097

.

http://ar.inel.gov/owa/getimage_2?F_PAGE=1&F_DOC=INEEL/EXT-98-01097&F_REV=00.

[4] R. Patteson (2000). The Accelerated Site Technology Deployment Program / Segmented Gate System Project. In Spectrum 2000 Conference; Chattanooga TN 50 (US) 09/24 / 2000-09 / 28/2000.

http://www.osti.gov/scitech/servlets/purl/763108.

[5] R.W. Doane

,

RH. Grant

 (1994). Johnston Atoll Plutonium Contaminated Soil Cleanup Project. 5th quarterly report, 1 August 94 to 31 October 1994. Technical report, 1 August to 31 October 1994.

 5

[6] Genie 2000 Manual, Spectroscopy System-Operations. Canberra Industries, Meriden, CT. United States of America.

[7] P. Arce, J.I. Lagares, L. Harkness, D. Pérez-Astudillo, M. Cañadas, P. Rato, M. de Prado, Y. Abreu, G. de Lorenzo, M. Kolstein, A. Díaz. Gamos: “A framework to do Geant4 10 simulations in different physics fields with an user-friendly interface”. Nuc. Instr. Meth. A, Vol. 735, January 21, 2014, Pages 304–313)

Description of the invention

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The invention relates to a device for semi-industrial use for the measurement of activity and segregation of soils contaminated by transurans, and in particular by 241Am. The device disposes the earth in discrete samples, with cylindrical geometry and an approximate volume of 9.4 l. On these discrete samples the determination of activity (or alternatively mass concentration of activity) is carried out and based on this result, an automated system performs the segregation of the material.

The determination of the activity on the discrete samples is carried out with a system of four scintillation detectors of NaI (Tl) type FIDLER facing two to two. These FIDLER detectors are specific equipment for field measurement, designed to detect low energy radiation. In particular they are especially suitable for detecting the 59.54 keV gamma emission of 241Am present in contaminated land.

The device for measuring activity and segregation of land contaminated by 241Am object of the present invention comprises:

 - a support structure;

- a rotating element that swings in different positions around the support structure,

- a land container in which the land to be analyzed is deposited, where said container is integrated in the rotating element and has a mobile base; 35

- four FIDLER type NaI (Tl) scintillation detectors facing two to two at a distance from each other that allows the passage of the earth vessel, and configured to determine, by detecting low energy radiation, whether the earth contained in the container are or are not contaminated by 241Am;

 40

The positions of the rotating element include:

- A filling position in which an operator performs the manual loading of land in the land container.

 Four. Five

- A measuring position in which the earth container is located in the space between the four scintillation detectors facing each other (preferably at a distance of 2 cm from the detectors), and in which the simultaneous measurement of the earth container is carried out lands, with scintillation detectors that are activated.

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- Two different discharge positions, one for the discharge of uncontaminated material and another for the discharge of contaminated material, in which the lands of the

Land container is discharged, by opening its base, respectively to a dump container of uncontaminated material or a dump container of contaminated material.

In a preferred embodiment, the device also comprises a control panel 5 responsible for governing the movement of the rotating element by means of an automaton.

The earth container is preferably cylindrical and made of methacrylate.

In a preferred embodiment, the support structure comprises a central base connected by means of support arms to a circular structure.

The device may also comprise a hopper integral with the rotating element and through which the earth vessel is fed with discrete samples of earth.

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The device preferably comprises a digital electronics associated with the scintillation detectors for pulse counting, and a computer connected to said digital electronics, in charge of the control and operation of the scintillation detectors.

In a preferred embodiment the scintillation detectors are preferably configured to perform the measurement with different levels of filling of the earth container (preferably 100%, 75%, 50% or 25%).

The device can use a modeling of the measuring system of the device for the calculation of efficiency values, corresponding to different earth densities and for 25 different levels of container filling.

In a preferred embodiment the discharge position of uncontaminated material corresponds to the filling position and the discharge position of contaminated material corresponds to a different position from the filling position and the measuring position. 30 The filling position, the measurement position and the discharge position of contaminated material preferably correspond to 0 °, 90 ° and 180 ° rotation positions, respectively, of the rotating element.

The large area of the active volume (cylindrical scintillation crystal of 127 mm in diameter) 35 makes these detectors capable of inspecting large surfaces in relatively short times. Its small thickness of 2 mm makes the influence on the measure of other gamma-emitting radionuclides of greater energy minimal. In addition, these detectors are protected by a DELRIN plastic cover, which mechanically provides them with the robustness necessary for use in unfavorable conditions. This cover 40 practically does not interfere with the 59.54 keV photons.

The detectors are associated with digital electronic systems, controlled from a computer. The spectra recorded by each of the four detectors are sent to a program where they process and obtain the results necessary to put into operation the mechanisms of segregation of the material.

The device implies an integral development of a specific machine for the measurement of activity and segregation of lands contaminated with 241Am. It is based on the disposition of the land to be evaluated in discrete samples, in an optimized geometry and volume, and with a large capacity to measure activity on these samples, when using four FIDLER detectors facing each other. The system can discriminate contaminated soils with concentrations

activity levels of less than 1 Bqg-1 of 241Am, with measurement times of 15 s and in standardized volumes of 9.4 l.

Brief description of the drawings

 5

A series of drawings that help to better understand the invention and that expressly relate to an embodiment of said invention which is presented as a non-limiting example thereof is described very briefly below.

Figures 1A, 1B and 1C show a perspective, plan and elevation view, 10 respectively, of a particular embodiment of the device for measuring land with FIDLER detectors.

Figures 2A, 2B and 2C show the operating positions provided in the device: manual loading and unloading position of the uncontaminated material (Figure 2A), measuring position 15 of the earth container (Figure 2B) and material unloading position contaminated (Figure 2C).

Figure 3 shows in detail the measurement position with four FIDLER detectors around the earth vessel. twenty

Figure 4 represents in detail the unloading of the earth container on a discharge container.

Figure 5 shows a side view of the device where the front of the 25 control panel can be seen.

Figure 6 shows the start and input screen of measurement parameters of the computer program that controls the device.

 30

Figure 7 shows a list with the efficiency values for different densities of the lands considered.

Figure 8 shows the connection buttons of the detectors.

 35

Figure 9 shows an example of the result of the measurements made by the four FIDLER detectors.

Figure 10 shows the spectra obtained by the FIDLER detectors.

 40

Figure 11 shows the modeling of the basic components of the detectors used.

Figure 12 shows the modeling of the four FIDLER detectors arranged in the device. Four. Five

Detailed description of the invention

In a preferred embodiment shown in Figures 1A, 1B and 1C (perspective, plan and elevation view, respectively), the device of the present invention comprises a support structure that integrates and / or supports various electromechanical systems of the device, formed in a preferred embodiment by a central base 17 with diameters of

67 and 90 cm in the upper and lower part respectively, joined by support arms 18 to a circular structure 19 with an outside diameter of 222 cm and an inside diameter of 211.5 cm. It also comprises a rotating device 12 supported by the central base 17 and which swings around the support structure in three different positions. The support structure (17, 18) and the circular structure 19 are made of electro-welded and machined steel 5, being removable and self-supporting. The support structure is anchored in concrete floor by bolts or screws, common in fixing small structures. In the support structure materials and finishes are used that facilitate its cleaning and eventual radioactive decontamination.

 10

In the rotating element 12 a land container 3 is arranged jointly and severally. Through a top hopper 2, also integral with the rotating element 12, the device is fed with the earth, ensuring its flow to the land container 3, which is of cylindrical shape (20 cm in diameter, 30 cm high and approximately 9.4 l capacity). The material of the earth container 3 is made of extruded methacrylate 3 mm thick, with sufficient mechanical strength and commercially available, which facilitates the replacement of the container in case of breakage.

The rotating element 12 moves in the horizontal plane in a field of ± 100 ° by servo-controlled rotation drive. Three positions of the rotating element 12 20 are provided for its operation:

- A filling position 4 (0 ° position), in which an operator 13 performs the manual loading of land and where the discharge of the uncontaminated material is also carried out to an unloading container 8 of uncontaminated material. 25

- A measuring position 5 (90 ° position), in which simultaneous measurement of the earth vessel 3 is carried out with four FIDLER detectors.

- A position for discharge of contaminated material 6 (position 180 °), in which land from contaminated material is unloaded to a container 8 ’for discharge of contaminated material.

The device also has a control panel 7, located in the 270º position, which always acts with two hands for safety reasons. The control panel 7 governs 35 the movement of the rotating element 12 by means of an automaton with display and whose programming language allows its integration into personal computers, in particular the Genie 2K environment of Canberra [6], which is used for configuration and acquisition of data from FIDLER equipment.

 40

Depending on the measurement results (contaminated or uncontaminated material), the earth container 3 will move according to the filling position 4 or the discharge position of contaminated material 6 (0 ° or 180 ° positions), where the content will be discharged respectively into the unloading container 8 of uncontaminated material or into the unloading container 8 'of contaminated material (implemented for example in 45 drums of 50 l capacity), avoiding the production of dust during this operation.

Figures 2A, 2B and 2C show the different operating positions (4, 5, 6) of the rotating element 12 provided in the device.

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In the filling position 4 (Figure 2A), the earth is manually loaded by an operator 13 through the small hopper 2, located at an approximate height of

1.25 m with respect to the ground. In order to reduce the emission of dust, during the loading of the lands, sufficient protections are available (the upper part of the hopper 2 is covered with suitable plastic or canvas) and an extraction system aimed at the hopper 2 is enabled. The lands enter by gravity in the land container 3.

 5

In measurement position 5 (Figure 2B) the measurement is made. Figure 3 shows this situation in detail with the rotating element 12 located in the measurement position 5. In this measurement position there are up to four FIDLER detectors 9 located around the earth container 3, at a distance of approximately 2 cm. The device has height-adjustable brackets 15 that allow to position the FIDLER detectors 10 9 around the earth container 3, which will be operated with digital electronics 11 connected to a control unit (for example a personal computer) via USB and / or Ethernet, and which will also be connected to the control automaton of the rotating element 12.

Depending on the measurements recorded on the land container 3, a personal computer 15 sends a signal to the electronics of the rotating element 12 which rotates to the filling position 4 or to the discharge position of contaminated material 6 (Figure 2C) as required. been the result of the measure. Next, the land container 3 is emptied by opening its base on the corresponding unloading container (8, 8 ’). The device contemplates the structures and precise extractions to avoid the dispersion of dust. Figure 4 represents in detail, for the situation shown in Figure 2C, the unloading of the earth container 3 onto the discharge container 8 ′ of contaminated material.

Figure 5 shows a side view of the device where the front of the control panel 25 7 can be seen.

The measurement process in the device is detailed below. In the first place, an operator 13 opens a deposit with land to be analyzed and pours its contents into the land container 3, ensuring that no dust is produced and that no more spill is given than the expected 30 indicated by maximum levels marked in the geometry standard. The remains of the tank are dragged manually with the help of brushes or brushes. After loading the earth container 3, a lid is placed in said container 3 to close it tightly and avoid dispersion of the material.

 35

The measurement process is carried out with a computer program developed for this purpose that controls the automaton of the device in the following order:

First, the sample identification data is entered. The program will give visual and acoustic signal for the start of the measurement. 40

2º Next and for safety reasons, it is necessary to act with both hands on the control cabinet 7, with which the container moves to the measuring position 5.

 Four. Five

3rd The measurement is carried out under the selected configuration. The container will automatically move to the filling position 4 to discharge the uncontaminated land or to the discharge position of contaminated material 6 to discharge the contaminated land, depending on the results obtained in the measurement.

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In a particular embodiment, the FIDLER PROBE 127 BRA2 / 5M-Q-X detector is used, which allows the detection of low energy radiation, in particular the 59.54 keV photons emitted by the 241Am present in the contaminated land.

The characteristics of the thallium-activated sodium iodide scintillation crystal, NaI (Tl), 5 are: diameter 127 mm and thickness 2 mm. The NaI crystal (Tl) is coupled to a 130 mm diameter photomultiplier tube through a 51 mm thick quartz guide.

- Entrance window: 0.0025 mm aluminum> 10 keV, with extra protection of 20 µm Kaptón. 10

- DELRIN plastic material coverage (3 mm thick).

 Each of the FIDLER 9 detectors has an associated digital electronics 11 for pulse counting with the following characteristics:

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- Multichannel analyzer for scintillation detectors with connection to computer via USB and Ethernet.

- 60 MHz analog / digital converter with 2048 channel gain.

- Operation modes PHA, MCS, SCA and MSS.

- 1300 V high voltage source with 1 mA maximum current and 20 100 V / s rise ramp.

- 8912 channel memory.

- Compatible with Genie 2000 v 3.2 program from Camberra Industries.

For the control and operation of the detectors a sealed personal computer is used and external to the control cabinet 7, with Flash disks (without motors) of 60 GB, 2 GB RAM and external display, keyboard and mouse.

The characterization process is completed in approximately 15 s. The power supply is single phase 220 V AC, with a power of 1.5 kW, requiring the specific differential 30 suitable for the motors.

Figure 6 shows the start screen of the computer program that governs the device. As you can see it is divided into different zones:

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 Selection of active FIDLER 9 detectors: Data are only acquired with the marked detectors, these controls are intended to continue the operation in the event of failure of any of the detectors.

 Detector status: Shows the working conditions of the activated detectors and the analyzer status, indicating possible errors. 40

 Keypad. It consists of three buttons:

o Connection: Opens the detectors and associates them with the measurement system.

o Measurement: Starts the measurement process of the equipment.

o Disconnection: Release the detectors so that they can be used by another user or program. Four. Five

 Mechanics status indicators: These indicators show the situation in which the mobile elements of the machine are.

 Identification: Sample data read from the automaton.

 Results: There are two types of results:

o The values of the integral of the peak 50 measured against that of the applied bottom are represented in the upper table.

o The values corresponding to the activity, uncertainty and detection limit of 241Am, calculated for each of the activated detectors, are written in the lower table.

 Spectra: representation of the different spectra obtained from active detectors. 5

Figure 7 shows a list with the efficiency values for different densities of the lands considered. The efficiency values are stored in a database, in a table. This table defines the FIDLER 9 detector to which the geometry, its description and the corresponding energy efficiency value of 10 59.54 KeV, corresponding to 241Am, apply. The geometry selection is made in the program start screen by means of a drop-down that shows the name of the geometry. The name must match on the four FIDLER 9 detectors as they are selected in block.

To measure it is necessary to indicate the FIDLER 9 detectors that are active and connect the program with them (Figure 8). This function is performed with the Connection button. Initially the Measurement and Disconnection buttons are disabled; they are only activated after the connection to the FIDLER 9 detectors has been successful. If the control system is switched off, the Automatic indicator must be disabled. When connecting to the detectors, the program reads their configuration and displays it in the zone of 20 Identification.

In manual mode, after connecting to the detectors with the Connection button, when pressing the Measure button, or when receiving the measurement position signal 5 from the PLC, the measurement process begins, acquiring the different spectra, which are shown Real time 25 on the program screen. It is convenient to have previously completed the identification fields of the sample; The program only needs to work the measurement time that reads it from a startup file.

The interval in which the peak of 241Am is expected to be treated is marked by a file of 30 regions of interest, ROI extension, associated with each of the FIDLER 9 detectors. When the spectra collection ends, because the analyzer has reached the selected time, the program saves the spectra of each of the detectors in a file, identified by the date and time of measurement. This data (Figure 9) is stored by the program. 35

Next, the integral corresponding to the peak window is determined; This interval is calculated with the initial and final channels of the region of interest. The value of said integral divided by the measurement time is shown in the zone corresponding to Integral and fund results, in the Counting box. The same operation is performed to determine the corresponding integral of the background spectrum, the result is shown in the Fund box. The results are listed sorted by the detector number; The difference between the two values, Net, is shown in the last box.

The program then analyzes the spectrum (Figure 10). For this purpose, it loads the Efficiency / Energy calibration corresponding to the geometry of the sample and calculates the activity, uncertainty and decision threshold from the counts calculated in the previous section.

The values obtained, both area and analysis, in addition to being displayed, 50 are stored in a database or in a text file. The format of this file is as follows:

- Date.

- Hour.

- Identification

- Weight.

- Commentary. 5

- State.

- Integral of first detector.

- Integral of the fund associated with the first detector.

- Net worth.

- 241Am activity of the first detector. 10

- Uncertainty of the 241Am activity of the first detector.

- Decision threshold of the first detector.

- Integral of second detector.

- Integral of the fund associated with the second detector.

- Net worth. fifteen

- 241Am activity of the second detector.

- Uncertainty of the 241Am activity of the second detector.

- Decision threshold of the second detector.

- Integral third detector.

- Integral of the fund associated with the third detector. twenty

- Net worth.

- 241Am activity of the third detector.

- Uncertainty of the 241Am activity of the third detector.

- Decision threshold of the third detector.

- Integral of fourth detector. 25

- Integral of the fund associated with the fourth detector.

- Net worth.

- 241Am activity of the fourth detector.

- Uncertainty of the 241Am activity of the fourth detector.

- Decision threshold of the fourth detector. 30

Each field is separated from the next by the tab character. Each measure is a line that is added to the file. If there is a missing field, or several fields in case there are inactive detectors, the separator tabs between fields are maintained, so that the values are always in a column. This file, having tabs such as a field separator, can be read directly from Excel and can be treated in the spreadsheet.

The modeling of the measuring system of the device is explained below. The variations in density and the different chemical compositions that the soils normally present, make it advisable to have a mathematical modeling (characterization) of the detection system, which allows obtaining the efficiency values (necessary for the activity / mass concentration determinations of activity) more suitable for the various types of soils, without having to resort to experimental efficiency calibrations. Four. Five

The modeling of the measurement system (Figure 11) also allows the calculation of the efficiencies corresponding to various types of soil and the calculation of the efficiency in those cases in which the methacrylate cylinder that houses the soil sample is not completely full, but present different levels of filling. fifty

Therefore, the measuring system of the device with the calculation code GEANT-4 has been modeled. This code, recognized internationally, is based on the application of specific mathematical methods (Monte-Carlo methods), to simulate the interaction of radiation with the measurement system.

 5

The GEANT-4 code is executed in CIEMAT's “EULER” cluster whose basic characteristics are the following: 144 Intel (R) Xeon (R) CPUs E5450 @ 3.0GHz, 8 cores / node, total 1152 processors. Memory 16GB / node.

In addition, to facilitate the handling of the GEANT4 code, an interface developed 10 is also used in CIEMAT, "GAMOS" [7]. The output data obtained with the code GEANT4 (GAMOS), correspond to the response of each of the four FIDLER 9 detectors installed in the device. The treatment of these data, from which efficiency is calculated, is carried out with the Mathematica 4 program.

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The 3D-EXPLORATION v 1.71 visualization program allows visualization, not only of the simulated geometry by means of the GEANT4 (GAMOS) code, but also of the interactions that have taken place with the measurement system. To carry out the modeling of the complete measurement system (Figures 11 and 12), it is necessary to first model the basic components of the type of detectors used (in a preferred embodiment 20, FIDLER PROBE 127 BRA2 / 5M-Q-X detectors).

Once one of the detectors is modeled, the modeling performed is checked by comparing the spectra obtained by exposing the detector to a point source of 241Am (Figure 11). 25

Finally, the four FIDLER 9 detectors arranged in the device are modeled (Figure 12).

In this way, the results are obtained from the efficiency of the different soil densities and the different fillings of the methacrylate cylinders (Figure 7).

Claims (13)

1. Device for measuring activity and segregation of lands contaminated by 241Am, characterized in that it comprises: 5  - a support structure (17); - a rotating element (12) that swings in different positions around the support structure, 10 - a land container (3) in which the lands to be analyzed are deposited, where said container (3) is integrated in the rotating element (12) and has a mobile base; - four scintillation detectors (9) of NaI (Tl) FIDLER type facing two to two to 15 a distance from each other allowing the passage of the earth vessel (3), and configured to determine, by detecting low energy radiation , if the lands contained in the container (3) are contaminated by 241Am or not; where the positions of the rotating element (12) include: 20 a filling position (4) in which an operator (13) performs the manual loading of land in the land container (3); a measuring position (5) in which the earth container (3) is located in the space between the four scintillation detectors (9) facing each other and in which the simultaneous measurement of the earth container (3) is carried out , with scintillation detectors (9) that are activated; two different unloading positions, one for the discharge of non-contaminated material and another for the discharge of contaminated material, in which the lands of the earth container (3) are unloaded, by opening their base, respectively to a container (8) discharge of uncontaminated material or a container (8 ') of discharge of contaminated material.  35 2. Device according to claim 1, characterized in that it comprises a control panel (7) responsible for governing the movement of the rotating element (12) by means of an automaton. 3. Device according to any of the preceding claims, characterized in that the earth container (3) is cylindrical. 4. Device according to any of the preceding claims, characterized in that the earth container (3) is methacrylate.  Four. Five Device according to any of the preceding claims, characterized in that the support structure comprises a central base (17) connected by means of support arms (18) to a circular structure (19). Device according to any of the preceding claims, characterized in that it comprises a hopper (2) integral with the rotating element (12) and through which the earth vessel (3) is fed with discrete samples of earth. Device according to any of the preceding claims, characterized in that it comprises a digital electronics (11) associated with the scintillation detectors (9) for pulse counting, and a computer connected to said digital electronics (11), in charge of the control and operation of scintillation detectors (9). 5 Device according to any of the preceding claims, characterized in that the scintillation detectors (9) are configured to perform the measurement with different levels of filling of the earth container (3).  10 9. Device according to claim 8, characterized in that the scintillation detectors (9) are configured to perform the measurement with the earth container (3) filled at 100%, 75%, 50% or 25%. 10. Device according to any of claims 8 to 9, characterized in that it uses a modeling of the measuring system of the device for the calculation of efficiency values, corresponding to different earth densities and for different levels of filling of the container (3) . Device according to any of the preceding claims, characterized in that the unloading position of uncontaminated material corresponds to the filling position (4) and the unloading position of contaminated material (6) corresponds to a position different from the position filling (4) and measuring position (5). 12. Device according to claim 11, characterized in that the filling position (4), the measuring position (5) and the discharge position of contaminated material (6) correspond to rotational positions of 0º, 90º and 180º, respectively, of the rotating element (12). 13. Device according to any of the preceding claims, characterized in that in the measuring position (5) the earth vessel (3) is located at a distance of substantially 2 cm from the detectors (9).