METHOD FOR THE RADIATION MONITORING OF MOVING OBJECTS AND A RADIATION PORTAL MONITOR FOR CARRYING OUT SAID METHOD

• US 20110261650A1
• Filed: 12/04/2009
• Published: 10/27/2011
• Est. Priority Date: 12/09/2008
• Status: Abandoned Application

• Current Assignee: Alexandr Georgievich Sorokin, Jury Losifovich Olshansky
• Original Assignee: Alexandr Georgievich Sorokin, Jury Losifovich Olshansky
• Inventors: Sorokin, Alexandr Georgievich, Olshansky, Jury losifovich
• Application Number:
  US13/132,919
• Publication Number:
  US 20110261650A1
• Time in Patent Office: Days
• US Class Current: 367/89
• CPC Class Codes: G01S 15/88 Sonar systems specially adapted for specific applications seismic or acoustic prospecting or detecting G01V1/00
• CPC Class Codes: G01S 7/52004 Means for monitoring or calibrating short-range imaging G01S7/5205
• CPC Class Codes: G01T 1/00 Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation G01T3/00, G01T5/00 take precedence
• CPC Class Codes: G01T 1/167 Measuring radioactive content of objects, e.g. contamination whole body counters G01T1/163

Abstract

The invention relates to radiation monitoring and can be used for detecting radioactive materials during the unauthorized movement thereof. The method involves registering background gamma quanta and detecting a monitored object in a monitoring zone when the registered gamma radiation exceeds the background radiation. The moment when an object arrives at a distance Rπ from gamma radiation detectors is determined and the moment when the object moves away from the gamma radiation detectors to a distance Rγ is determined. The gamma quanta are registered from the moment when the object arrives at the given distance Rπ from the gamma radiation detectors to the moment when the object moves away from the gamma radiation detectors to the distance Rγ. Rπ=(0.8−1.2)(H+D) and Rγ=(0.8−1.2)(H+D), where H is the height of the horizontal plane that is the plane of symmetry of the position of the gamma radiation detectors; and D is half the distance between two gamma radiation detectors mounted at the same height. The monitor comprises the following components accommodated in a twin-post portal: a controller with a signaling unit, gamma radiation detectors with amplifiers and analog-to-digital converters, an object detection sensor based on an ultrasonic oscillation source and an ultrasonic oscillation receiver, a detection signal amplifier, a detector, a smoothing filter and an object detection and distance recording unit. The invention makes it possible to decrease the smallest detectable mass of radioactive material.

Claims

1. A method for the radiation monitoring of moving objects, including:

a registration of background gamma quanta by at least two gamma-ray detectors,

counting the background gamma quanta recorded over a given time interval,

detecting the test object in the control zone,

a registration of gamma quanta by at least two gamma-ray detectors when controlled object is located in the control zone,

counting of gamma quanta recorded over a given time interval when controlled object is located in the control zone,

a comparison of number of gamma quanta recorded over the given time interval when controlled object is located in the control zone with the number of background gamma quanta recorded over the given time interval, and

providing a decision about the presence of the radioactive material in the controlled object at the excess of number of gamma quanta recorded over the given time interval when controlled object is located in the control zone over the number of background gamma quanta registered during the given time interval,

characterised in that

after the detection of the test object in the control zone a moment when the controlled object arrives at a given distance R_P from the gamma-ray detectors is determined,

a moment when the controlled object moves away from the gamma-ray detectors to a given distance R_U is determined and

a registration of gamma quanta when controlled object is located in the control zone is carried out from the moment when the controlled object arrives at the given distance R_P from the gamma radiation detectors to the moment when the controlled object moves away from the gamma radiation detectors to the given distance R_U, where the distance R_P and R_U is set according to the formula R_P=(0.8−

1.2)·

(H+D) and R_U (0.8−

1.2)·

(H+D), where H—

the height of the horizontal plane which is a symmetry plane of gamma-ray detectors location;

D—

the half of the distance between the two gamma-ray detectors installed at the same height.

2. The method according to claim 1, wherein in the control zone an ultrasonic vibrations are emitted in the control zone, ultrasonic vibrations reflected from the controlled object are accepted and converted into electrical signal, the electrical signal is increased, a component of the electrical signal proportional to the distance to the controlled object is selected by a bandpass frequency filter, the said component of electrical signal is detected and smoothed and the moment when the controlled object arrives at a given distance R_P from the gamma-ray detectors and the moment when the controlled object moves away from the gamma-ray detectors to a given distance R_U are determined by comparing the said component of the electric signal with at least one threshold value established in accordance with the values of the given distance R_P and the given the distance R_U.

3. The method according to claim 1, wherein an ultrasonic vibrations are emitted in the control zone, ultrasonic vibrations reflected from the controlled object are accepted and converted into electrical signal, the electrical signal is increased, a component of the electrical signal proportional to the speed of the controlled object is selected by a bandpass frequency filter, the said component of electrical signal is detected and smoothed, it compared with the established threshold, and in case of excess of the said component of the electric signal over the threshold the decision is made whether violation of the rules of movement through the control zone by the controlled objects was occurred.

4. The method according to claim 1, wherein an ultrasonic vibrations are emitted in the control zone, ultrasonic vibrations reflected from the controlled object are accepted and converted into electrical signal, the electrical signal is increased, a component of the electrical signal proportional to the intensity of the ultrasonic noise in the control zone is selected by a bandpass frequency filter, the said component of electrical signal is detected and smoothed and resulting smoothed component is subtracted from the electric signal.

5. The method according to claim 1, wherein the magnitude of time interval between the moments of electrical signals shaping by at least with two crossing sensors, which are designed as the source and receiver of optical radiation, placed opposite to each other on the opposite sides with respect to trajectory of controlled object movement in the control zone, and set in the plan at a given distance, is determined, the said magnitude of the time interval is compared with the established threshold, and decision is made about violation of the rules of movement through the control zone by the controlled object when threshold value exceeds the referred time interval.

6. The method according to claim 1 or 5, wherein the current time since the moment of the controlled object detection in the control zone until the moment of forming an electrical signal by at least one crossing sensor is measured, the current time is compared with established threshold, and decision is made about violation of the rules of movement through the control zone by the controlled object if the value of the current time exceeds the established threshold.

7. A radiation portal monitor comprising a two-frame portal, allocated in the portal controller with a connected alarm unit, at least two gamma-ray detectors with series connected incorporated amplifier and analog-digital converter connected to the input of the controller, and object detection sensor, characterised in that it is equipped with an series connected object detection signal amplifier, the first detector, the first smoothing filter and unit of object detection and distance recording that is connected by the output to the input of controller, at that the object detection sensor is designed as a source and receiver of ultrasonic vibrations, and the input of the object detection signal amplifier connected to the output of ultrasonic vibrations receiver.

8. The monitor according to claim 7, characterised in that it is equipped with amplification automatic control unit connected by the input to the output of the first smoothing filter and the object detection signal amplifier is arranged with possibility to adjust its amplification ratio and its amplification control input is connected to the output of amplification automatic control unit.

9. The monitor according to claim 7, characterised in that the said unit of object detection and distance recording contains the series connected a first bandpass frequency filter, a second detector, a second smoothing filter and a distance registration threshold device with a threshold level equals to the value of the electric signal at its input when the controlled object is located at a given distance from the gamma-ray detectors, equals to (0.8−

1.2)·

(H+D), where H—

the height of the horizontal plane which is a symmetry plane of gamma-ray detectors location;

D—

the half of the distance between the two gamma-ray detectors installed at the same height.

10. The monitor according to claim 7, characterized in that it is equipped with object speed recording unit containing series-connected a second bandpass frequency filter, a third detector, a third smoothing filter and speed registration threshold device, and the input of the said second bandpass frequency filter and the output of the said speed registration threshold device are connected respectively to the output of the first smoothing filter and the input of the controller.

11. The monitor according to claim 7, characterized in that it is equipped with noise recording unit, comprising series-connected third bandpass frequency filter, the fourth detector and a fourth smoothing filter, and the input of the third bandpass frequency filter connected to the output of the first smoothing filter and the output of the fourth smoothing filter connected to the inputs of the first and second bandpass frequency filters.

12. The monitor according to claim 7, characterized in that it is equipped with at least two crossing sensors installed in the alignment of the two-frame portal at the same horizontal plane at the assigned distance from each other, each of which is designed as a optical radiation source and a optical radiation receiver mounted on the opposite frames of the portal across from each other, and with at least two circuits containing series-connected a crossing signal amplifier and a crossing signal threshold device, and the crossing signal amplifier input is connected to the optical radiation receiver output, and the output of crossing signal threshold device is connected to the controller input.