EP3722011A1 - Method and conveying device for processing and sorting materials potentially contaminated with radioactive substances - Google Patents

Abstract

The invention relates to a method for treating and sorting materials (10) potentially contaminated with radioactive substances, a) unsorted materials (10) being conveyed on a conveyor (1), b) individual areas of the unsorted materials (10) in the course the conveyance on the conveyor device (1) are measured with regard to at least one form of ionizing radiation, c) the measured values thus determined being temporarily stored and assigned to that area of the conveyed materials (10) that is in the measuring area of the at least one at the time of recording The sensor (2; 21) determining the measured value is located, d) wherein the conveyed materials (10) are fed to at least one selection device (3) at one position of the conveying device (1), in particular at its end, which the conveyed materials ( 10) forwards to one of at least two material flows depending on a selection signal, e) the respective selection signal forwarded to the at least one selection device (3) being determined as a function of the measured value or measured values assigned to the part of the materials (10) located in the area of the selection device (3).

Description

The invention relates to a method for treating and sorting materials potentially contaminated with radioactive substances in accordance with patent claim 1 and a conveyor system in accordance with patent claim 12.

A large number of sorting methods are known from the prior art with which different materials can be separated in a simple manner, for example based on their grain size. In the case of materials potentially contaminated with radioactive substances, it is problematic and involves great effort to subject the material conveyed on a conveyor to a selection so that materials that are contaminated are reliably separated from the materials that are not contaminated and, if necessary, in different containers be promoted.

It is fundamentally desirable here that uncontaminated materials are not mixed with contaminated materials, since the uncontaminated materials are, for example, to be dumped or brought into the environment in some other way. Mixing of contamination-free materials with contaminated materials should therefore be prevented. Likewise, it should be avoided that too large amounts of uncontaminated materials get to the contaminated materials, since this would increase the amount of materials that are laborious to dispose of or temporarily store and thus the disposal and / or storage costs would increase significantly.

The object of the invention is therefore to provide a method for sorting materials potentially contaminated with radioactive substances, which ensures a reliable separation between contaminated and non-contaminated materials.

1. a) wobei unsortierte Materialien auf einer Fördereinrichtung gefördert werden,
2. b) wobei einzelne Bereiche der unsortierten Materialien im Zuge der Beförderung auf der Fördereinrichtung in Hinblick auf zumindest eine Form von ionisierender Strahlung vermessen werden,
3. c) wobei die so ermittelten Messwerte zwischengespeichert und demjenigen Bereich der geförderten Materialien zugeordnet werden, der sich zum Aufnahmezeitpunkt im Messbereich des zumindest einen den Messwert ermittelnden Sensors befindet,
4. d) wobei die geförderten Materialien an einer Position der Fördereinrichtung, insbesondere an dessen Ende, zumindest einer Selektionseinrichtung zugeführt werden, die die bei ihr einlangenden geförderten Materialien in Abhängigkeit von einem Auswahlsignal an einen von zumindest zwei Materialströmen weiterleitet,
5. e) wobei das jeweilige an die zumindest eine Selektionseinrichtung weitergeleitete Auswahlsignal in Abhängigkeit von demjenigen Messwert oder denjenigen Messwerten ermittelt wird, der oder die dem im Bereich der Selektionseinrichtung befindlichen Teil der Materialien zugeordnet wurde.

The invention solves this problem with a method for treating and sorting materials potentially contaminated with radioactive substances according to claim 1. According to the invention, it is provided that

1. a) where unsorted materials are conveyed on a conveyor,
2. b) whereby individual areas of the unsorted materials are measured in the course of transport on the conveyor device with regard to at least one form of ionizing radiation,
3. c) the measured values determined in this way being temporarily stored and assigned to that area of the conveyed materials which is located in the measuring area of the at least one sensor determining the measured value at the time of recording,
4. d) wherein the conveyed materials are fed to at least one selection device at one position of the conveying device, in particular at its end, which forwards the conveyed materials arriving at it to one of at least two material flows as a function of a selection signal,
5. e) wherein the respective selection signal passed on to the at least one selection device is determined as a function of that measured value or those measured values that was assigned to the part of the materials located in the area of the selection device.

Such a method advantageously enables a reliable separation between materials contaminated with radioactive substances and non-contaminated materials on the basis of the measured values that were determined with regard to at least one type of ionizing radiation, for example beta or gamma radiation. The selection device advantageously ensures that the materials are assigned to a material flow on the basis of the measured values assigned to them so that contaminated and non-contaminated materials are conveyed separately from one another, for example into different containers.

When the selection signal changes, the selection device advantageously feeds the material previously conveyed into the selection device to the corresponding material flow in order to ensure a reliable separation between materials contaminated with radioactive substances and non-contaminated materials.

Such a method thus enables the materials not only to be assessed and sorted in fixed, predetermined quantity units (batch sizes), but also that the system can advantageously adapt the assignment to the material flows at any point in time by changing the selection signal in the event of changes in the material.

A particularly reliable selection signal can be provided if the individually determined measured values are fed to a digital filter,
it is provided in particular that the individual measured values are weighted and / or totaled and / or that a maximum value is determined among the individual measured values, and
that such a filtered measured value signal determined by filtering is used to form the selection signal.

In order to ensure a particularly precise separation of contaminated and non-contaminated materials, it can be provided that, for the formation of the selection signal, measured values are used that were recorded a predetermined time period before, this time period corresponding in particular to the time that the materials were transported from the recording area of the at least one sensor corresponds to the position of the selection device on the conveyor device.

A particularly small-scale examination of the unsorted materials potentially contaminated with radioactive substances can be achieved if measurements are made with a large number of sensors of the same type, with the receiving area of each of the sensors only covering a partial area of the width of the conveyor device,
that a selection is carried out with a plurality of separate selection devices, each selection device being assigned to one of the sensors and the selection devices and sensors assigned to one another each covering the same partial area of the width of the conveyor device, and
that the formation of the individual selection signals for the selection devices is carried out in each case on the basis of the temporarily stored measured values of the respective sensor assigned to the selection device.

A particularly reliable sorting of materials potentially contaminated with radioactive substances that emit different types of radioactive radiation can be achieved if a plurality of sensors that are sensitive to different types of radiation and / or energy ranges are provided for or for each selection device , which each determine measured values in relation to areas of the conveyed materials, which each reach a selection device, and
wherein the individual measured values, which are each assigned to the same area of conveyed materials, are stored together and used to form the selection signal for actuating the respective selection device.

A particularly reliable sorting of potentially contaminated materials on the basis of the measured values of different sensors can be ensured by measuring values of different, for different, for the formation of the selection signal Types of radiation and / or energy ranges of sensitive sensors are used, each of which has been recorded different predetermined time periods beforehand, these periods of time corresponding in particular to the time that corresponds to the conveyance of the materials from the recording area of the respective sensor to the position of the selection device on the conveyor.

A further improvement in the sorting or separation between contaminated and uncontaminated materials can be achieved if a mean value, in particular a sliding mean value, or a maximum value based on the in a predetermined time interval preceding the point in time at which the materials accumulate the position of the selection device are located on the conveying device, recorded measured values of the sensors are determined and used as a selection signal for forwarding the conveyed materials.

A particularly reliable separation of materials that are contaminated with radioactive substances that emit gamma radiation can be ensured if the results of a gamma spectral measurement for a number of different particle energies are used as the measured value, with
a weighted sum of the individual spectral measurement values of the gamma spectrum is used in particular when creating the selection signal, with individual areas of the gamma spectrum that are assigned to certain radioactive substances of interest being weighted higher than the other areas.

A particularly reliable separation of materials that contain beta emitters can be achieved if the beta radiation intensity is used as the measured value.

In the event that several sensors of the same type are arranged next to one another and / or one behind the other in the transport direction, a reliable correction of the measured values with regard to the influence of transverse radiation can be provided if the receiving area of each of the sensors only covers a partial area of the width of the conveyor , and
that a corrected measured value is ascertained by subtracting the measured values of temporally or spatially adjacent conveyor subareas in weighted form from the measured value ascertained in each case of a conveyor device sub-area.

A particularly reliable correction of gamma measured values with regard to the influence of transverse irradiation can be ensured if a corrected Gamma measurement value is determined and if energy-dependent weighting of the neighboring gamma measurement values is carried out as part of the correction, in particular if higher-energy components of the gamma measurement values are weighted more heavily than lower-energy components of the gamma measurement values during the deduction.

A particularly reliable estimate of the radiation attributable to pure beta emitters can be ensured if a comparison of the individual gamma measured values, in particular the results of the gamma spectral measurement, for a number of different particle energies with the beta radiation measured values, each relating to the same range or partial area of the conveyed materials were determined, the presence of pure beta emitters being determined and the activity of the pure beta emitters being estimated.

A measure of the total contamination of the contaminated materials that were conveyed into a container can be provided if the individual measured values for which the same selection signal was determined and which were recorded with regard to materials that were assigned to the same material flow are accumulated,
it is provided in particular that an accumulation of all gamma measurement values or beta radiation measurement values is carried out, which are supplied to the same container.

A measure of the contamination with individual radioactive substances of interest that are present in the materials that were conveyed in a container can be provided if the measured values determined for the materials conveyed into the same container, in particular the results of the gamma Spectral measurement for a number of different particle energies can be accumulated, a mass-specific measured variable being determined for each container, and an accumulated measured value, in particular the specific activity, of certain radioactive nuclides of interest being derived for the respective container.

A further improvement in the sorting of materials potentially contaminated with radioactive substances can be achieved if, in a first sorting pass, it is recognized as contaminated and / or uncontaminated and materials forwarded by the at least one selection device to a relevant material flow are conveyed on the conveyor device in at least one new sorting pass and in Be measured with regard to at least one form of ionizing radiation,
a selection signal for the respective selection device being determined again in each case as a function of that measured value or those measured values which was assigned to the part of the materials located in the area of the selection device.

A particularly small-scale sorting of the materials potentially contaminated with radioactive substances can be achieved if the creation of the selection signal and the forwarding of the conveyed materials to one of the at least two material streams takes place continuously as a function of the selection signal.

A particularly rapid sorting of larger quantities of materials potentially contaminated with radioactive substances can be achieved if the creation of the selection signal and the forwarding of the conveyed materials to one of the at least two material flows as a function of the selection signal is carried out discontinuously for specified units of measure, in particular in batches.

• eine, insbesondere kontinuierlich laufende, Fördereinrichtung zum Befördern von unsortierten Materialien,
• zumindest einen Sensor, der auf die Fördereinrichtung gerichtet ist und dazu ausgebildet ist, einzelne Bereiche der unsortierten Materialien im Zuge der Beförderung auf der Fördereinrichtung in Hinblick auf zumindest eine Form von ionisierender Strahlung zu vermessen,
• zumindest eine Selektionseinrichtung, der die geförderten Materialien an einer Position der Fördereinrichtung, insbesondere an deren Ende, zugeführt werden, wobei die Selektionseinrichtung dazu ausgebildet ist, die bei ihr einlangenden geförderten Materialien in Abhängigkeit von einem Auswahlsignal an einen von zumindest zwei Materialströmen weiterzuleiten und
• eine dem zumindest einen Sensor nachgeschaltete und mit der zumindest einen Selektionseinrichtung verbundene Steuer- und Verarbeitungseinheit, wobei die Steuer- und Verarbeitungseinheit dazu ausgebildet ist,
  • die von dem zumindest einen Sensor ermittelten Messwerte zwischenzuspeichern und demjenigen Bereich der geförderten Materialien zuzuordnen, der sich zum Aufnahmezeitpunkt im Messbereich des den Messwert ermittelnden Sensors befindet,
  • ein Auswahlsignal in Abhängigkeit von demjenigen Messwert oder denjenigen Messwerten zu ermitteln, der oder die dem im Bereich der Selektionseinrichtung befindlichen Teil der Materialien zugeordnet wurde, und
  • das jeweilige Auswahlsignal an die zumindest eine Selektionseinrichtung weiterzuleiten.

The invention further relates to a conveyor system for the treatment and sorting of materials potentially contaminated with radioactive substances, in particular for carrying out a method according to the invention

• a, in particular continuously running, conveyor device for conveying unsorted materials,
• at least one sensor which is directed at the conveyor and is designed to measure individual areas of the unsorted materials in the course of the conveyance on the conveyor with regard to at least one form of ionizing radiation,
• at least one selection device to which the conveyed materials are fed at a position of the conveying device, in particular at the end thereof, the selection device being designed to forward the conveyed materials arriving at it to one of at least two material flows as a function of a selection signal and
• a control and processing unit connected downstream of the at least one sensor and connected to the at least one selection device, the control and processing unit being designed to
  • to temporarily store the measured values determined by the at least one sensor and to assign them to that area of the conveyed materials that is in the measuring area of the sensor determining the measured value at the time of recording
  • to determine a selection signal as a function of the measured value or measured values assigned to the part of the materials located in the area of the selection device, and
  • forward the respective selection signal to the at least one selection device.

When the selection signal changes, the selection device advantageously feeds the material previously conveyed into the selection device to the corresponding material flow in order to ensure a reliable separation between materials contaminated with radioactive substances and non-contaminated materials. In this way, the materials can not only be used in fixed units of measure, i.e. Batch sizes are evaluated and sorted, but can advantageously be assigned to the corresponding material flow at any point in time when the measured values of the materials change by changing the selection signal.

A conveyor system configured in this way advantageously enables a reliable separation between materials contaminated with radioactive substances and non-contaminated materials, since the selection signal for the selection device from the control and processing unit is based on the measured values obtained by the at least one sensor with regard to at least one type of ionizing radiation, for example beta or gamma radiation, were measured. The control and processing unit controls the selection device according to the selection signal, so that it is advantageously ensured that the materials are assigned to a corresponding material flow based on the measured values assigned to them, and such contaminated and non-contaminated materials are conveyed separately from one another, for example into different containers.

• wenn die Förderanlage eine Vielzahl von gleichartigen Sensoren umfasst, wobei der Aufnahmebereich jedes der Sensoren jeweils nur einen Teilbereich der Breite der Fördereinrichtung abdeckt,
• wenn eine Vielzahl von separaten Selektionseinrichtungen vorgesehen ist, wobei jede Selektionseinrichtung jeweils einem der Sensoren zugeordnet ist und die einander zugeordneten Selektionseinrichtungen und Sensoren jeweils denselben Teilbereich der Breite der Fördereinrichtung abdecken, und
• wenn die Steuer- und Verarbeitungseinheit dazu ausgebildet ist, die einzelnen Auswahlsignale für die Selektionseinrichtungen jeweils aufgrund der zwischengespeicherten Messwerte des jeweiligen der Selektionseinrichtung zugeordneten Sensors zu ermitteln.

A particularly detailed examination of the unsorted, potentially radioactive material contaminated materials can be achieved,

• if the conveyor system comprises a plurality of sensors of the same type, the receiving area of each of the sensors only covering a partial area of the width of the conveyor system,
• when a plurality of separate selection devices is provided, each selection device being assigned to one of the sensors and the selection devices and sensors assigned to one another each covering the same partial area of the width of the conveyor device, and
• if the control and processing unit is designed to determine the individual selection signals for the selection devices in each case on the basis of the temporarily stored measured values of the respective sensor assigned to the selection device.

A particularly reliable sorting of potentially radioactive materials that emit different types of radioactive radiation, contaminated materials can be achieved if the conveyor system for or for each selection device has a plurality of sensors located one behind the other in the transport direction and sensitive to different types of radiation and / or energy ranges comprises, wherein the sensors are each designed to determine measured values in relation to areas of the materials conveyed, each of which reaches a selection device, and
if the control and processing unit is designed to jointly store the individual measured values, which are each assigned to the same area of conveyed materials, and to use them when generating the selection signal for actuating the respective selection device.

A particularly reliable separation of contaminated with radioactive nuclides and non-contaminated materials can be provided if the control and processing unit is designed to determine a selection signal according to a method according to the invention and / or a measured value according to a method according to the invention.

A particularly small-scale sorting of the materials potentially contaminated with radioactive substances can be achieved if the control and processing unit is designed to continuously generate the selection signal and the at least one selection device is designed to continuously transfer the conveyed materials to one of the at least two material flows in To forward depending on the selection signal.

A particularly rapid sorting of larger quantities of potentially radioactive materials can be achieved if the control and processing unit is designed to produce the selection signal discontinuously for specified units of measure, in particular batchwise, and the at least one selection device is designed to select the conveyed materials discontinuously in predetermined quantity units, in particular batchwise, to one of the at least two material streams as a function of the selection signal.

Further advantages and configurations of the invention emerge from the description and the accompanying drawings.

The invention is shown schematically in the following with the aid of particularly advantageous but not restrictive exemplary embodiments in the drawings and is described by way of example with reference to the drawings.

• Fig. 1 eine schematische Darstellung einer Förderanlage zur Durchführung eines ersten Ausführungsbeispiels eines erfindungsgemäßen Verfahrens,
• Fig. 2 einen Ausschnitt einer Förderanlage gemäß Fig. 1 mit einem Sensor,
• Fig. 3 einen Ausschnitt einer Förderanlage gemäß Fig. 1 mit mehreren Sensoren,
• Fig. 4 ein erstes Auswertungsbeispiel,
• Fig. 5 eine schematische Darstellung des Einflusses von Quereinstrahlung auf die Messwerte einzelner Sensoren,
• Fig. 6 ein zweites Auswertungsbeispiel mit Berücksichtigung der Quereinstrahlung.

Below show:

• Fig. 1 a schematic representation of a conveyor system for performing a first embodiment of a method according to the invention,
• Fig. 2 a section of a conveyor system according to Fig. 1 with a sensor,
• Fig. 3 a section of a conveyor system according to Fig. 1 with multiple sensors,
• Fig. 4 a first evaluation example,
• Fig. 5 a schematic representation of the influence of transverse irradiation on the measured values of individual sensors,
• Fig. 6 a second evaluation example with consideration of the cross irradiation.

Fig. 1 shows a schematic representation of a conveyor system 100 for carrying out a method according to the invention. As in Fig. 1 As can be seen, the conveyor system 100 comprises a conveyor device 1, for example a conveyor belt, on which materials 10 potentially contaminated with radioactive substances are conveyed. The potentially contaminated materials 10 can be, for example, bulk goods such as loose rock material of various grain sizes, but also potentially contaminated waste.

At the end of the conveying device 1, the potentially contaminated materials 10 to be sorted reach a selection device 3. Such a selection device 3 can be, for example, a rotatably mounted drum which has walls 31a, 31b, 31c protruding radially from the drum axis, so that cup segments 32a, 32b, 32c are thereby formed. Materials 10 falling from the conveying device 1 reach these cup segments 32a, 32b, 32c and are conveyed into different containers 4a, 4b, for example barrels.

For this purpose, the selection device 3 has a drive unit 32 which rotates the selection device 3 and thus the cup segments 32a, 32b, 32c of the selection device 3 by an arc section of, for example, 120 ° and the materials 10 depending on the direction of rotation of the selection device 3 in different containers 4a, 4b are funded.

To sort the materials 10 potentially contaminated with radioactive substances, the unsorted materials 10 are first placed on the conveyor 1, distributed and conveyed on the conveyor 1 or the conveyor belt under at least one sensor 2. If a particularly even distribution of the unsorted materials 10 is to be achieved, the conveyor system 100 can optionally e.g. Include a rake that ensures that the conveying device 1 is occupied as evenly as possible. Optionally, the conveyor system 100 can include, for example, an optical belt scale in order to check this occupancy of the conveyor device 1, to make a statement about the bulk thickness possible and to detect a lack of occupancy at an early stage.

In the course of the transport, individual areas of the unsorted materials 10 are measured with regard to at least one form of ionizing radiation. A wide variety of variants are possible with regard to the sensor structure. In a first, simple embodiment of a method according to the invention, a conveyor system 100 with only one sensor 2 for ionizing radiation is used, as shown in FIG Fig. 2 is shown schematically. The sensor 2 is in Fig. 2 arranged normal to the transport direction T of the conveyor 1 and its measuring range extends over the entire width of the conveyor 1.

The sensor 2 is in data communication with a control and processing unit 5, and the measured values determined by the sensor 2 are temporarily stored in a memory 51 of the control and processing unit 5. The measured values are assigned to that area of the conveyed materials 10 which is in the measuring area of the sensor 2 at the respective recording time. The position of the measured conveyed materials 10 on the conveyor 1 can e.g. determined via the position change between two measurements by a rotary encoder on a non-driven roller and assigned by the control and processing unit 5 to the respectively determined measured values.

At the end of the conveying device 1, the conveyed materials 10 are fed to the selection device 3, which receives the conveyed materials 10 depending on a selection signal to one of at least two material flows. The selection signal is generated as a function of that measured value that was assigned to the materials 10 that are currently in the area of the selection device 3.

The control and processing unit 5 is connected to the selection device 3 or its drive unit 32 and activates the drive unit 32 of the at least one selection device 3 for rotation. The direction of rotation depends on the determined selection signal, so that the materials 10 are fed to the corresponding material flow, and such contaminated and non-contaminated materials are conveyed separately from one another into different containers 4a, 4b. Such a configuration of the conveyor system advantageously makes it possible to transport materials 10 not only in predetermined quantity units or batch sizes, i.e. discontinuous, assess and sort. Alternatively, the materials 10 can be used at any time, e.g. when the measured values determined for the materials 10 are changed, they can be assigned to the corresponding material flow by changing the relevant selection signal.

For this purpose, for example, a selection signal is continuously provided for those materials 10 that have currently been fed from the conveyor device 1 to the selection device 3 or have entered a cup segment 32a, 32b, 32c of the selection device 3, so that these materials 10 are also continuously fed by the selection device 3 material flow corresponding to the selection signal. This means that a forwarding to the corresponding material flow in the most varied of partial quantities is possible at any time, for example if the measured value determined for the respective materials 10 exceeds a predetermined limit value.

As an alternative to this simple exemplary embodiment of a method according to the invention, in which only one sensor 2 for ionizing radiation is used, a more complex structure with a plurality of sensors can also be used. For example, two sensors 2, 21 sensitive to different types of radiation can also be arranged one behind the other, viewed in the direction of transport T. This can be, for example, a sensor 2 for gamma radiation and a sensor 21 for beta radiation. Optionally, more than two sensors that are sensitive to different types of radiation and / or energy ranges can also be arranged one behind the other.

The sensors 2, 21 arranged one behind the other can each determine measured values in relation to a measuring area 20 which covers the entire width of the conveyor device 1 or the conveyor belt. The individual measured values are each stored in the memory 51 of the control and processing unit 5, all of the measured values that originate from the same area of the conveyed materials 10 being stored together and used when generating the selection signal for actuating the selection device 3.

Optionally, the measurements can also be carried out with a large number of sensors 2a, ..., 2d; 21a, ..., 21d, as exemplified in Fig. 3 is shown. The receiving area of each of the sensors 2a, ..., 2d; 21a, ..., 21d in each case only covers a partial area 1a, ..., 1d of the width of the conveyor device 1 or of the conveyor belt.

Such a sensor arrangement is in Fig. 3 shown by way of example where four sensors 2a, ..., 2d which are sensitive to gamma radiation, for example, are arranged next to one another in the transport direction T, so that the receiving area 20a, ..., 20d of each of the sensors 2a, ..., 2d each has a partial area 1a,. .., 1d covers the width of the conveyor belt. In the exemplary embodiment shown, a further sensor 21a, ..., 21d, which is sensitive to other types of radiation and / or energy ranges, is arranged in front of each of the sensors 2a,..., 2d, viewed in the transport direction T. However, this is by no means absolutely necessary and an efficient sorting of potentially contaminated and non-contaminated materials 10 can also be achieved with a method according to the invention if only one type of sensor is used.

The coverage area of the further different sensors 21a,..., 21d has in the exemplary embodiment in Fig. 3 the same width as the coverage area 20a, ..., 20d of the sensors 2a, ..., 2d.

As in Fig. 3 is shown, in such a device with a number of sensors 2a, ..., 2d; 21a, ..., 21d equipped conveyor system 100a made the selection with a plurality of separate selection devices 3a, ..., 3d. Each selection device 3a, ..., 3d is one of the sensors 2a, ..., 2d; 21a, ..., 21d or the respectively covered sub-area 1a, ..., 1d assigned to the width of the conveyor device 1. This means that the selection devices 3a, ..., 3d and sensors 2a, ..., 2d; 21a, ..., 21d each cover the same partial area 1a, ..., 1d of the width of the conveyor 1.

The selection signal for each of the selection devices 3a, ..., 3d is generated on the basis of the temporarily stored measured values of the sensors 2a, ..., 2d; 21a, ..., 21d determined. This means, for example, that the selection signal for the selection device 3a is based on the measured values of the sensors 2a; 21a is formed as shown in Fig. 3 is shown.

For the formation of the selection signal, measured values are used, the time of which they were recorded a predetermined time span back. In the exemplary embodiments shown, this time period corresponds to FIG FIGS. 1 to 6 the time it takes for the materials 10 to be transported from the receiving area of the respective sensor 2a, ..., 2d; 21a, ..., 21d corresponds to the position of the selection device 3 on the conveyor device 1.

In the event that several sensors 2a, ..., 2d; 21a, ..., 21d, the z. B. are sensitive to different types of radiation and / or energy ranges, determine measured values in relation to regions of the materials 10 conveyed, as shown in FIG Fig. 3 is shown, different predetermined time periods are taken into account. This is due to the fact that the time spans that elapse until the materials 10 arrive from the receiving area of a respective sensor to the position of the selection device 3a,..., 3d on the conveyor device 1 are different.

Determination of a selection signal

In a method according to the invention, the selection signal for controlling a selection device 3 or a plurality of selection devices 3a,..., 3d can be determined in different ways by digital filters. In connection with the invention, such a digital filter is understood to mean, for example, the weighting and totaling of the individually determined measured values or the determination of a maximum value among the individual measured values. For example, an average can e.g. a moving average or a maximum value can be formed on the basis of the measured values determined.

This mean value or maximum value can be determined, for example, for the unsorted materials 10 which are transported past a relevant sensor, for example a gamma detector, within a predetermined time interval, as shown in FIG Fig. 4 is shown. The time interval can be adapted to the recording area of the respective sensor 2, 21 and a length of several seconds, for example exhibit. If the mean value or maximum value determined in this way exceeds a predetermined threshold value Th, the relevant materials 10 are considered to be contaminated and are assigned to the relevant material flow by the relevant selection device 3.

Alternatively, a selection signal based on the gamma or beta measurement values averaged over a variable time interval, e.g. depends on the extent of the change in the measured values over time.

If the sensors used are beta radiation detectors, for example, on the basis of, for example, a sliding average value over the beta radiation measured values, e.g. the beta radiation intensity, a selection signal for the forwarding of the conveyed materials 10 can be derived within a defined time interval of, for example, several seconds.

Furthermore, alternatively, on the basis of the over a defined, short time interval of e.g. 1 s, summed beta radiation measured values a sorting decision or a related selection signal based on the maximum beta radiation measured value within a defined longer interval of e.g. 16 s can be derived.

In general, the use of the maximum of the measured values over a defined time interval as a selection signal is particularly advantageous, since in this case there is only a lower risk of underestimating the contamination, since statistical fluctuations towards lower measured values, which would incorrectly indicate a particularly low level of contamination, cannot be included in the sorting criterion.

Influence of cross irradiation

For the formation of a selection signal, at least one sensor 2, which covers the entire width of the conveying device 1, determined measured values of a gamma spectral measurement for a number of different particle energies can be used. As an alternative to this, several sensors 2a,..., 2d of the same type arranged next to one another can be used to determine gamma spectra. Such a sensor structure for determining gamma radiation measured values is shown in the exemplary embodiment in FIG Fig. 5 shown. When creating the selection signal, a weighted sum of the individual spectral measurement values of the gamma spectrum is used, for example.

If the receiving area 20a, ..., 20d of each of the sensors 2a, ..., 2d only covers a partial area 1a, ..., 1d of the width of the conveyor 1 or the conveyor belt, cross irradiation from adjacent measuring areas can also contribute for the measured value that a respective sensor 2a, ..., 2d measures, as shown in Fig. 5 is shown.

Fig. 5 shows three sensors 2a, 2b, 2c with receiving areas 20a, 20b, 20c, which each detect conveyor device subareas 1a, 1b, 1c. For the in Fig. 5 The sensor 2b shown with the receiving area 20b, for example, provides material 10 that is conveyed on the adjacent sub-areas 1a, 1c of the conveyor 1 or radiation that is emitted by these materials 10, a contribution to the measured value that the sensor 2b measures. This means that lateral irradiation of material components that are not directly below the recording area 20b, but are immediately adjacent thereto, makes a contribution to the measured value in the recording area 20b.

Radiation from the sections of sub-area 1b of conveyor 1 that have already moved out of receiving area 20b of detector 2b or have not yet entered receiving area 20b also provides radiation components that are detected by sensor 2b. A measured value corrected for this influence of transverse irradiation is determined by taking the measured values of temporally or spatially adjacent conveyor system subareas 1a, ..., 1d from the measured value determined for a recording area 20a, ..., 20d of a conveyor device sub-area 1a, ..., 1d. .., 1d can be deducted in weighted form.

A schematic example of this procedure is shown in Fig. 6 shown. Fig. 6 shows a section of three conveyor device subregions 1a, 1b, 1c of a conveyor device 1 that moves along the transport direction T. For the receiving area 20b of the in Fig. 5 sensor 2b shown, a gamma spectrum is recorded and should be based on the contribution of the gamma spectra that were determined for locally right and left adjacent conveyor device sub-areas 1a, 1c and the contribution of the gamma spectra that were determined for the temporally preceding and subsequent areas of sub-area 1b have been determined.

To clarify this procedure, in Fig. 6 the gamma spectrum to be corrected of the recording area 20b of the detector 2b, as well as the gamma spectra to be taken into account for the correction of the locally adjacent or chronologically preceding and following conveyor device sub-areas are shown schematically.

The correction is indicated schematically by subtraction symbols between the relevant gamma spectra.

For the correction, for example, the sensors 2a, 2c generate spectra for the locally adjacent recording areas 20a, 20c shown in FIG Fig. 5 are shown, recorded and stored in memory 51 of control and processing unit 5. The gamma spectra for which the sensor 2b for the temporally preceding or following area of the sub-area 1b were or are also recorded in the memory 51. A respective gamma spectrum is corrected, for example, by a weighted, for example, percentage subtraction of the neighboring spectra.

For the correction of the determined gamma measurement values, energy-dependent weighting of the neighboring gamma measurement values can also be undertaken, with higher-energy components of the gamma measurement values being weighted more heavily than lower-energy components when subtracting. For the creation of the selection signal, individual areas of the gamma spectrum that are assigned to certain radioactive substances of interest can also be weighted higher than the other areas.

Weighting factor or quotient sum

For the formation of a selection signal, measured values from a gamma spectral measurement for a number of different particle energies can also be used with at least one sensor 2, which covers the entire width of the conveyor device 1, as a basis for calculating weighting factors or sums of quotients. For example, germanium detectors can be used for such a gamma spectral measurement.

In this case, the control and processing unit 5 sums up, for example, the individually determined gamma spectra of the respective sensors 2 sensitive to gamma radiation based on their position information over a predetermined length of the conveyor belt or a predetermined time interval, the length of which is adapted to the size of the recording area of the respective sensor 2 .

Thus, for a given measuring time of, for example, one second and a transport speed of the conveyor device 1 of, for example, 1 cm / s and a summation over, for example, a conveyor belt length of 230 mm, the current 23 individual gamma spectra are summed up on average. With each new single gamma spectrum that is recorded, the chronologically oldest gamma spectrum of the specified time interval is no longer taken into account for the formation of the sum.

The total activity of a respective nuclide i under a respective sensor k results for a specific point in time as follows: $${\mathrm{A.}}_{\mathrm{ik}}={\mathrm{counts}}_{\mathrm{i}}/\left(\mathrm{life\; time}*\mathrm{efficiency}*\mathrm{abundance}\right)$$

A_ik

Gesamtaktivität des Nuklids i unter dem jeweiligen Sensor k, Einheit: [Bq]

counts_i

die in einem Zeitintervall innerhalb der region of interest (ROI) für das jeweilige Nuklid i am jeweiligen Sensor k gezählten Impulse [dimensionslos]

life time

die aktive Messzeit des für Gammastrahlung sensitiven Sensors k während des Zeitintervalls, innerhalb dessen die counts gezählt wurden, Einheit: [s]

efficiency

die Detektoreffizienz (Detektor- und Geometrie-spezifisch) bei der für das entsprechende Nuklid i charakteristischen Strahlungsenergie, Einheit: [counts pro ausgesandtem Teilchen]

abundance

die Wahrscheinlichkeit, mit der das Radionuklid i die Gammastrahlung der entsprechenden Energie aussendet, Einheit: [generierte Teilchen in s^-1/Bq]

Are there

A _ik

Total activity of the nuclide i under the respective sensor k, unit: [Bq]

counts _i

the pulses counted in a time interval within the region of interest (ROI) for the respective nuclide i at the respective sensor k [dimensionless]

life time

the active measuring time of the sensor k, which is sensitive to gamma radiation, during the time interval within which the counts were counted, unit: [s]

efficiency

the detector efficiency (detector and geometry-specific) with the radiation energy characteristic of the corresponding nuclide i, unit: [counts per emitted particle]

abundance

the probability with which the radionuclide i emits the gamma radiation of the corresponding energy, unit: [generated particles in s ^-1 / Bq]

The weighting factor for a respective nuclide i results for a sensor k for a specific point in time as: $${\mathrm{WF}}_{\mathrm{ik}}={\mathrm{A.}}_{\mathrm{ik}}/\left({\mathrm{Dimensions}}_{\mathrm{k}}*{\mathrm{limit}}_{\mathrm{i}}\right)$$

WF_ik

Weighting factor für Nuklid i für den jeweiligen Sensor k, Einheit: [dimensionslos]

A_ik

Gesamtaktivität des Nuklids i unter dem jeweiligen Sensor k, Einheit: [Bq],

Masse_k

die unter dem Messfenster befindliche Gesamtmasse in [g], konstanter Faktor auf Basis der bisherigen Erfahrungen

Grenzwert_i

Grenzwert für dieses Nuklid in [Bq/g]

There are:

WF _ik

Weighting factor for nuclide i for the respective sensor k, unit: [dimensionless]

A _ik

Total activity of the nuclide i under the respective sensor k, unit: [Bq],

Mass _k

the total mass under the measurement window in [g], constant factor based on previous experience

Limit value _i

Limit value for this nuclide in [Bq / g]

Mit WF_k

Weighting factor für den jeweiligen Sensor k, Einheit: [dimensionslos]

WF_ik

Weighting factor für as jeweilige Nuklid i und den jeweiligen Sensor k, Einheit: [dimensionslos]

The total weighting factor for a respective sensor k for a specific point in time is thus: $${\mathrm{WF}}_{\mathrm{k}}={\mathrm{\Sigma iWF}}_{\mathrm{ik}}$$

With WF _k

Weighting factor for the respective sensor k, unit: [dimensionless]

WF _ik

Weighting factor for the respective nuclide i and the respective sensor k, unit: [dimensionless]

So overall for the weighting factor for a respective sensor k: $${\mathrm{WF}}_{\mathrm{k}}={\mathrm{\Sigma }}_{\mathrm{i}}{\mathrm{counts}}_{\mathrm{i}}/\left(\mathrm{life\; time}*\mathrm{efficiency}*\mathrm{abundance}*{\mathrm{Dimensions}}_{\mathrm{k}}*{\mathrm{limit}}_{\mathrm{i}}\right)$$

Activity details

If the unsorted materials 10, as described above, are conveyed into container 4 by means of a selection unit 3 or various selection devices 3a,..., 3d, a nuclide-specific activity information can optionally also be determined for each container 4. For this purpose, for example, the individual gamma measurement values or beta radiation measurement values for which the same selection signal was determined and which were recorded with reference to materials 10 that were assigned to the same material flow are accumulated, for example added up.

Optionally, a conveyor system 100 for carrying out a method according to the invention can also comprise a weighing unit 40 for a container 4 or several containers 4a,..., 4d. For example, the net weight of the container 4; 4a, ..., 4d can be determined during operation, which, given a constant level of filling of the container 4; 4a, ..., 4d inferences about the density of the materials 10 which are in the respective container 4; 4a, ..., 4d have been funded. To monitor the level of the container 4; 4a,..., 4d, the conveyor system 100 can include a fill level sensor 30.

Optionally, a specific activity information per container 4 or 4a, ..., 4d can be determined. For this purpose, as described above, an accumulated activity is determined for a respective container 4, the weight of the respective container 4 is determined by weighing and a specific activity is determined from these two details.

A total weighting factor for a respective container 4; 4a, ..., 4d results, assuming that the term mass _{k is} constant, as the mean value over all WF _k which are in the respective container 4; 4a, ..., 4d are assigned.

Comparison of gamma and beta radiation measurements

In addition, for the formation of the selection signal for the selection device 3 or several selection devices 3a,..., 3d and / or the activity information, a A comparison of the gamma measurement values determined for the same area or sub-area of the conveyed materials 10 with the respectively determined beta radiation measurement values can be carried out. Since it is known for radioactive nuclides which types of radiation or with which activity they emit radiation, a comparison of the gamma measured values with the beta radiation measured values can be used to estimate whether in addition to nuclides or substances that have both gamma and Beta radiation emitted, substances are present that only emit beta radiation. In this way, the pure beta emitters can be estimated and their activity determined.

Multiple sorting passes

Optionally, a method according to the invention for treating and sorting materials 10 potentially contaminated with radioactive substances can also be designed as a multi-stage method.

Thus, for example, the materials 10 classified as contaminated in a first sorting pass can be re-evaluated in at least one new sorting pass with changed parameters, for example different threshold values, for the creation of the selection signal.

In a first sorting pass, for example, a relatively low threshold value can be used for sorting out as contaminated material, e.g. it is not known which radionuclides are present in the materials 10 to be sorted. If a subsequent analysis of the measured values determined for the materials 10 reveals that only nuclides are present which allow a higher threshold value than the sorting threshold, in this case a new sorting run can take place with an adapted threshold value.

A reassessment of the materials 10 classified as contaminated in a first sorting pass can also take place, for example, if during an optional weighing of a respective container 4; 4a, ..., 4d it is subsequently recognized that the bulk density of the materials 10 was underestimated. The effect of this is that if an activity is calculated per mass or per container 4, this is overestimated.

A new sorting pass can also be carried out if, after a first sorting pass, it is found that largely harmless, non-contaminated or only slightly contaminated materials 10 are mixed with a few highly contaminated particles that cause isolated, high maxima in otherwise inconspicuous measured values. In this In this case, in a renewed second sorting pass with a high sorting value or threshold value, these contaminated particles can be sorted out from the materials 10 classified as contaminated. Since the highly contaminated particles were sorted out in this way in the second sorting pass, a further subsequent third sorting pass, in which a lower sorting value or threshold value is again selected, results in lower transverse radiation, which means that other parts of the material to be sorted are also recognized as uncontaminated first sorting pass were still recognized as contaminated due to the higher cross radiation there.

Alternatively, the materials 10 classified as uncontaminated in a first sorting pass can be re-evaluated in at least one new sorting pass with changed parameters, for example different threshold values, for the creation of the selection signal. This can be done, for example, if a subsequent analysis of the measured values determined for the materials 10 shows that one or more unexpected radionuclides are present for which e.g. a lower sorting value or sorting using sensors that are sensitive to gamma radiation would be required. Depending on the data situation, it is advantageous in this case to subject the materials 10 classified as non-contaminated to a sorting run again with parameters adapted to the nuclide in question.

Alternatively, such a new sorting pass can take place if, with an optional weighing of a respective container 4; 4a, ..., 4d it is subsequently recognized that the bulk density of the materials 10 was overestimated. In this case the activity per mass was underestimated. Depending on the data situation, it is advantageous in this case to re-sort the materials 10 classified as not contaminated with parameters adapted to the bulk density.

Claims (15)

Process for the treatment and sorting of materials potentially contaminated with radioactive substances (10), a) whereby unsorted materials (10) are conveyed on a conveyor device (1), b) wherein individual areas of the unsorted materials (10) are measured in the course of the transport on the conveyor device (1) with regard to at least one form of ionizing radiation, c) the measured values determined in this way being temporarily stored and assigned to that area of the conveyed materials (10) which, at the time of recording, is in the measuring area of the at least one sensor (2; 21) determining the measured value, d) the conveyed materials (10) being fed to at least one selection device (3) at one position of the conveying device (1), in particular at its end, which sends the conveyed materials (10) arriving at it to one of forwards at least two material streams, e) the respective selection signal forwarded to the at least one selection device (3) being determined as a function of the measured value or measured values assigned to the part of the materials (10) located in the area of the selection device (3). Method according to claim 1, characterized in that - that the individually determined measured values are fed to a digital filter,
it is provided in particular that the individual measured values are weighted and / or totaled and / or that a maximum value is determined among the individual measured values, and
that such a filtered measured value signal determined by filtering is used to form the selection signal
and or - That measured values are used for the formation of the selection signal that were recorded a predefined time period before, this time period corresponding in particular to the time that the conveyance of the materials (10) from the recording area of the at least one sensor (2, 21) to the position of the Selection device (3) on the conveyor (1) corresponds. Method according to one of the preceding claims, characterized in that measurements are carried out with a plurality of sensors of the same type (2a, ..., 2d; 21a, ..., 21d), the recording area of each of the sensors (2a, ..., 2d; 21a, ..., 21d) each covers only a partial area of the width of the conveyor device (1),
that a selection is made with a large number of separate selection devices (3a, ..., 3d), each selection device (3a, ..., 3d) each having one of the sensors (2a, ..., 2d; 21a, .. ., 21d) and the mutually assigned selection devices (3a, ..., 3d) and sensors (2a, ..., 2d; 21a, ..., 21d) each cover the same partial area of the width of the conveyor device (1) , and
that the formation of the individual selection signals for the selection devices (3a, ..., 3d) is based on the temporarily stored measured values of the respective sensor (2a, ..., 2d; 21a,. .., 21d) is made. Method according to one of the preceding claims, characterized in that for the or for each selection device (3; 3a, ..., 3d) a plurality of sensors (2) located one behind the other in the transport direction (T) and sensitive to different types of radiation and / or energy ranges ; 2a, ..., 2d; 21; 21a, ..., 21d) is provided, each of which determines measured values in relation to areas of the conveyed materials (10), which are each assigned to a selection device (3; 3a, ... , 3d), and
wherein the individual measured values, which are each assigned to the same area of conveyed materials (10), are stored together and used to generate the selection signal for actuating the respective selection device (3; 3a, ..., 3d). Method according to Claim 4, characterized in that measured values of different sensors (2; 2a, ..., 2d; 21; 21a, ..., 21d) sensitive to different types of radiation and / or energy ranges are used to form the selection signal, each of the different predefined periods of time recorded beforehand, these periods of time corresponding in particular to the time taken for the materials (10) to be conveyed from the recording area of the respective sensor to the position of the selection device (3; 3a, ..., 3d) on the conveying device ( 1). Method according to one of the preceding claims, characterized in that a mean value, in particular a sliding mean value, or a maximum value based on the in a predetermined time interval which precedes the point in time at which the materials (10) are at the position of the selection device ( 3; 3a, ..., 3d) are located on the conveyor device (1), recorded measured values of the sensors (2; 2a, ..., 2d; 21; 21a, ..., 21d) is determined and used as a selection signal for forwarding the conveyed materials (10). Method according to one of the preceding claims, characterized in that - That the results of a gamma spectral measurement for a number of different particle energies are used as the measured value, with
a weighted sum of the individual spectral measurement values of the gamma spectrum is used in particular when creating the selection signal, with individual areas of the gamma spectrum that are assigned to certain radioactive substances of interest being weighted higher than the other areas
and or - that the beta radiation intensity is used as the measured value. Method according to one of Claims 3 to 7, characterized in that the recording area of each of the sensors (2; 2a, ..., 2d; 21; 21a, ..., 21d) only has a partial area (1a, ..., 1d) covers the width of the conveyor device (1), and
that a corrected measured value is determined by subtracting the measured values of temporally or spatially adjacent conveyor system partial areas (1a, ..., 1d) in a weighted form from the measured value determined in each case for a conveyor device sub-area (1a, ..., 1d),
it is provided in particular that a corrected gamma measured value is determined and that an energy-dependent weighting of the neighboring gamma measured values is carried out as part of the correction,
in particular that higher-energy components of the gamma measurement values are weighted more heavily than lower-energy components of the gamma measurement values. Method according to one of the preceding claims, characterized in that a comparison of the individual gamma measured values, in particular the results of the gamma spectral measurement, for a number of different particle energies with the beta radiation measured values, each related to the same range or sub-range of the promoted Materials (10) were determined, is carried out, the presence of pure beta emitters being determined in this way and the activity of the pure beta emitters being estimated. Method according to one of the preceding claims, characterized in that the individual measured values were determined for the same selection signal and those in relation have been recorded on materials (10) that were assigned to the same material flow, are accumulated,
it is provided in particular that an accumulation of all gamma measurement values or beta radiation measurement values is carried out, which are fed to the same container (4; 4a, ..., 4d),
it is provided in particular that the measured values determined for the materials (10) conveyed into the same container (4; 4a, ..., 4d), in particular the results of the gamma spectral measurement for a number of different particle energies, are accumulated, with a mass-specific measured variable for each container (4; 4a, ..., 4d) is determined, and an accumulated measured value, in particular the specific activity, of certain radioactive nuclides of interest for the respective container (4; 4a, ..., 4d) is derived. Method according to one of the preceding claims, characterized in that - That in a first sorting pass recognized as contaminated and / or not contaminated and by the at least one selection device (3; 3a, ..., 3d) forwarded to a relevant material flow in at least one new sorting pass on the conveying device (1 ) funded and measured with regard to at least one form of ionizing radiation,
a selection signal for the respective selection device (3) is determined again depending on the measured value or measured values assigned to the part of the materials (10) located in the area of the selection device (3)
and or - that the creation of the selection signal and the forwarding of the conveyed materials (10) to one of the at least two material streams are carried out discontinuously for predetermined quantity units, in particular batchwise, or continuously as a function of the selection signal. Conveyor system (100) for treating and sorting materials (10) potentially contaminated with radioactive substances, in particular for carrying out a method according to one of Claims 1 to 11, comprising - a, in particular continuously running, conveying device (1) for conveying unsorted materials (10), - At least one sensor (2) which is directed to the conveyor (1) and is designed to detect individual areas of the unsorted materials (10) in the course of the To measure transport on the conveyor device (1) with regard to at least one form of ionizing radiation, - At least one selection device (3) to which the conveyed materials (10) are fed at a position of the conveying device (1), in particular at the end thereof, the selection device (3) being designed to select the conveyed materials (10 ) to forward depending on a selection signal to one of at least two material flows and - A control and processing unit (5) connected downstream of the at least one sensor (2) and connected to the at least one selection device (3), the control and processing unit (5) being designed to - to temporarily store the measured values determined by the at least one sensor (2) and to assign them to that area of the conveyed materials (10) which at the time of recording is in the measuring area of the sensor (2; 21) determining the measured value, - to determine a selection signal as a function of the measured value or measured values assigned to the part of the materials (10) located in the area of the selection device (3), and - Forward the respective selection signal to the at least one selection device (3). Conveyor system (100) according to claim 12, characterized in that
that a plurality of similar sensors (2a, ..., 2d; 21a, ..., 21d) is provided, the receiving area of each of the sensors (2a, ..., 2d; 21a, ..., 21d) in each case covers only part of the width of the conveyor device (1),
that a plurality of separate selection devices (3a, ..., 3d) is provided, each selection device (3a, ..., 3d) each having one of the sensors (2a, ..., 2d; 21a, ..., 21d ) is assigned and the mutually assigned selection devices (3a, ..., 3d) and sensors (2a, ..., 2d; 21a, ..., 21d) each cover the same partial area of the width of the conveyor device (1), and
that the control and processing unit (5) is designed to generate the individual selection signals for the selection devices (3a, ..., 3d) in each case on the basis of the temporarily stored measured values of the respective sensor (2a , ..., 2d; 21a, ..., 21d). Conveyor system (100) according to claim 12 or 13, characterized in that
that for or for each selection device (3; 3a,..., 3d) a plurality of one behind the other in the transport direction (T) for different types of radiation and / or energy ranges sensitive sensors (2; 2a, ..., 2d; 21; 21a, ..., 21d) is provided, the sensors (2; 2a, ..., 2d; 21; 21a, .. ., 21d) are each designed to determine measured values in relation to areas of the materials being conveyed (10), each of which reaches a selection device (3; 3a, ..., 3d), and
that the control and processing unit (5) is designed to jointly store the individual measured values, which are each assigned to the same area of conveyed materials (10), and when the selection signal is generated for actuating the respective selection device (3; 3a,. .., 3d). Conveyor system (100) according to one of Claims 12 to 14, characterized in that - That the control and processing unit (5) is designed to determine a selection signal according to one of Claims 2 to 6 and / or a measured value according to one of Claims 7 to 10
and or - That the control and processing unit (5) is designed to produce the selection signal discontinuously for predetermined units of measure, in particular batchwise, or continuously, and that the at least one selection device (3) is designed to discontinue the conveyed materials (10) in predetermined quantities To forward quantity units, in particular batchwise, or continuously to one of the at least two material streams as a function of the selection signal.

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