EA012257B1 - Device for detection radioactive materials - Google Patents

Abstract

Application: detection of radioactive materials during illicit trafficking of the mentioned materials in hand luggage, cargo and baggage through checkpoints of customs and other national sites; invention can also be used as gamma and neutron radiation monitors as part of the continuous environmental monitoring systems. Essence: in the device containing gamma detecting units, neutron detecting units consisting of slow neutron counters surrounded by neutron moderator, and amplifier of signals of the mentioned counters with shields of borated polyethylene, sensor indicating presence of an object in the search area, tamper sensor, information processing controller, alarm unit, power supply unit and control panel, the mentioned controller has a module connected measuring speed of the object moving through the search area, and between the mentioned neutron detecting units and mentioned controller there is an additionally installed program unit with the set algorithm capable of detecting - on the basis of statistical information received by measuring background pulse frequency from the mentioned neutron counters – fact of failure of any of them and exclude – should there is such a case – information on the number of pulses received from the detected inoperative counter, from the general flow of data on the number of pulses coming from the mentioned detecting units to the mentioned controller. Technical result: significant increase of reliability of radiation monitoring results.

Description

The invention relates to the field of detection of radioactive nuclear materials and is designed to detect unauthorized transported in the hand luggage, cargo and baggage of these materials through the checkpoints and customs checkpoints of customs and other objects of national economy. The invention can also be used to control the flux of gamma and neutron radiation in the composition of continuous environmental monitoring systems.

Known similar device GRM-22L, manufactured by SLIBECL (description attached). The device includes gamma-ray detection units consisting of plastic scintillation sensors connected to photomultipliers through their optical inputs, an object presence sensor in the monitored zone, an autopsy sensor, a metal detector, an information processing controller, alarm means and a power supply unit.

The device GRM-22L works as follows.

In the absence of a control object in the controlled area, the device measures the average number of background pulses per unit of time produced by the gamma-radiation detection units and stores it. When the presence signal of the monitoring object from the presence sensor appears, the device measures the number of pulses per unit of time from the gamma-ray detection units, compares this with the number of background pulses and, if it exceeds the background number, generates an alarm. The alarm is also generated in the event that metallic masses appear in the zone of control and in the event of unauthorized opening of the device.

The disadvantages of this device are the low detection efficiency of radioactive materials experiencing spontaneous fission by their neutron radiation, which limits the functionality of the device and the reliability of detection of a specified class of radioactive materials (for example, when packaging ²³⁹ Pu samples into lead protection), as well as low compliance with actual the probability of false alarms (P lt), asked (P zlt).

As a prototype, we consider the “Device for detecting radioactive materials” patent No. 2129289, consisting of a gamma-radiation detection unit, a neutron detection unit, an object presence sensor in a controlled area, an autopsy sensor, an information processing controller, an alarm unit, a power supply unit and a control panel , while the neutron radiation detection unit consists of counters of slow neutrons surrounded by a neutron moderator, and an amplifier of signals of the specified counters, and bonded controller is provided for receiving input information coming from said neutron radiation detection unit, equipped with screens of counters borated polyethylene thick, e.g., 70 mm.

The disadvantage of the prototype is low compliance with the actual probability of false alarms (P lt) specified (P zlt), and the disadvantage of the prototype is the lack of control of the speed of movement of the object in the control zone, which does not allow to evaluate compliance with the most critical conditions for measurements.

Since the detection characteristics of the radiation monitor are normalized only in a limited range of object velocities in the monitoring zone, an object exceeding the speed results in unreliable radiation monitoring results.

The purpose of this invention is to increase the reliability of the results of radiation monitoring.

The goal is achieved due to the fact that a device for measuring an object in the monitoring zone is additionally installed in a device containing a gamma detection unit, a neutron detection unit, an object presence sensor, an opening sensor, an information processing controller, an alarm unit, a power supply unit, a control panel. the neutron detection unit and the controller installed a software device with a given algorithm.

The drawing shows a block diagram of the proposed device, where

- gamma-radiation detection unit,

- neutron radiation detection unit,

- presence sensor,

- opening sensor,

- controller,

- alarm unit

- power supply unit

- battery

- Remote Control,

- software device

- system controller

- speed measurement module.

The principle of operation of the system is based on estimating the statistical parameters of the natural background radiation in the absence of a controlled object in the controlled space (background measurement mode), followed by comparing these parameters with the parameters of radiation from the controlled object (mode of the object) under the condition that the object speed corresponds to requirements. The estimated radiation parameters are the counts of the number of pulses from the detectors, the speed of the object in the measurement zone.

In the background measurement mode, the presence sensor (3) is turned off, and the background count values from the gamma (1) and neutron (2) detectors of the device are measured. The evaluation of the background values of the accounts is carried out by the controller (5).

When the presence sensor triggers (3), the device enters the object measurement mode. The result of each measurement is compared with the threshold values calculated from the last background estimate. Comparison and calculation of threshold values is performed by the controller (5). Additionally, using the speed measurement module (12), the controller (5) processes the results of measuring the speed of movement of each object in the control zone and compares the result with the set speed thresholds.

The controller (5) will output information to the control panel (9) and a signal to turn on the alarm (6) if the count value from the gamma (1) and / or neutron (2) detectors exceeds the corresponding threshold value.

If the count value from gamma (1) and / or neutron (2) detectors does not exceed the corresponding threshold value, but the measured object speed in the control zone exceeds the set values, the controller (5) will issue the relevant information to the control panel (9) . This measurement of the object is unreliable. In this case, the object is measured again. The measurement of an object is considered reliable only if the condition for compliance with the speed of the object in the control zone with the established restrictions is met.

To reduce false positives on the neutron channel for each neutron detection unit, when measuring the background with the help of the software device (10), the average value of each counter is calculated. When a deviation from this value by a specified amount, the counting results of this counter are not taken into account when calculating the total count from this detector, and the console receives information on the malfunction of the counter detected in this way. At the same time, the output from the operating mode from 1 to 3 counters, depending on the modification, will not significantly affect the sensitivity of the monitor to the neutron measurement.

Thus, the reliability of radiation monitoring of cargo, hand luggage, baggage and vehicles is increased.

Claims (1)

CLAIM A device for detecting radioactive materials during their unauthorized movement through a controlled space, including gamma-ray detection units, neutron radiation detection units, consisting of slow neutron counters surrounded by a neutron moderator, and a signal amplifier of these counters with borated polyethylene screens, controlled area, opening sensor, information processing controller, alarm unit, power supply unit and control panel This method is characterized by the fact that a module measuring the speed of an object moving through a controlled space is connected to the specified controller, and a software device with a predetermined algorithm is installed between the specified neutron radiation detection units and the specified controller, which can be detected based on the statistical information obtained by measuring the frequency of the background pulses from the indicated neutron counters, the fact of failure of any of them and in this case exclude the information on the number of them pulse coming from failure detection counter, the general information including the flow of pulses coming from said detecting unit to said controller.