CN110703294A - Portable nuclear radioactive substance detection system and detection method - Google Patents
Portable nuclear radioactive substance detection system and detection method Download PDFInfo
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- CN110703294A CN110703294A CN201911148433.0A CN201911148433A CN110703294A CN 110703294 A CN110703294 A CN 110703294A CN 201911148433 A CN201911148433 A CN 201911148433A CN 110703294 A CN110703294 A CN 110703294A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/20—Measuring radiation intensity with scintillation detectors
- G01T1/202—Measuring radiation intensity with scintillation detectors the detector being a crystal
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/167—Measuring radioactive content of objects, e.g. contamination
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0063—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with circuits adapted for supplying loads from the battery
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Abstract
A portable nuclear radioactive substance detection system and a detection method belong to the technical field of nuclear detection; the handheld device is not comprehensive in security and protection due to the operation limitation of a user; the system comprises an integrated high-voltage module, a scintillation detector, a pulse amplifier, a discrimination forming module and a microprocessor, wherein the integrated high-voltage module is sequentially connected with the scintillation detector, the pulse amplifier, the discrimination forming module and the microprocessor, and the microprocessor is respectively connected with a counting/metering display module, an alarm lamp and an electric quantity display module; the power supply management chip, the integrated high-voltage module, the pulse amplifier, the screening and forming module, the microprocessor, the lithium battery and the scintillation detector are arranged in the outer sleeve, the alarm lamp is arranged at the upper end of the outer sleeve, the counting/metering display module and the electric quantity display module are arranged at the upper parts of the front side and the rear side of the outer sleeve, and the lower end of the outer sleeve is connected with the base through a connecting ring; the system can form a detection channel with the isolation belt handrail, and meets the requirement of nuclear security; the method is a real-time online detection method for personnel and equipment in and out through radioactive substance detection by the combination of the system.
Description
Technical Field
The invention belongs to the technical field of nuclear detection, and particularly relates to a portable nuclear radioactive substance detection system and a detection method.
Background
In a typical terrorist act, the survivors will be rescued and treated and the non-victims will not be at risk after the terrorist act. An attack may lead to a psychological shock or threat, but this effect is limited in time and space; dust generated by terrorist acts can be diffused, fire disasters and building damages can also bring danger, but the substances have no inherent danger; the cleaning work is limited to a certain range, the immediate place where the event occurs is safe, and the legal investigation can be carried out by adopting the common method. Such events do not prevent the relevant authorities from providing normal government services.
When the radioactive substance scattering device explodes (nuclear dirty bomb), the situation is different, the radioactive substance pollutes the trauma, so that the casualty is very difficult to treat, and the casualty can still have the possibility of being survived and free from the trauma immediately after the attack; shrapnel and other generally harmless materials generated by an explosion will be contaminated by radioactive substances, and the affected area will be much larger than the incident site. Long-term health effects that cannot be seen visually and radiation threats that cannot be judged with certainty will cause the public to panic and eventually disturb social order.
Two typical approaches to nuclear and radiation terrorist threats: simple nuclear devices and radioactive distribution devices (nuclear dirty bombs or RDDs). Today only the former soviet union has thousands of tons of weapon grade nuclear material, plus tens of thousands of radioactive substances and a large number of orphan sources. Even if a very small part of such a radioactive substance falls into the hands of terrorists, it will cause an unexpected damage to the human society.
Strengthening nuclear security is the most effective method for preventing nuclear accidents and nuclear terrorism. The nuclear security includes 3 basic elements, detection, delay and response. Wherein, the detection refers to a technical means of detecting the occurrence of a nuclear security event and sending an alarm; delay refers to a technical means that can delay or prevent an adversary from performing an action; the response is a quick action taken to terminate the development of a nuclear security event. The detection among the 3 elements is most important, the occurrence of nuclear-related accidents can be avoided only by finding radioactive substances, and the detection of the radioactive substances is the basis for the development of nuclear security work.
At present, only in the occasions with extremely high security level (such as important leaders or meetings participated by foreign guests) security personnel can hold the radiation dosage instrument by hand to check the nuclear security, but the handheld equipment cannot meet the real nuclear security requirement due to the operation limitation of users.
Disclosure of Invention
The system adopts a column structure design integrating a scintillation detector and a power supply lithium battery, can form a detection channel with an isolation belt rail, can be quickly deployed at an entrance and an exit of important places such as nuclear facilities, frontier ports, subways, airports, large conference activities and the like for use, and truly meets the requirement of nuclear security; the method is a real-time online detection method for detecting whether people and equipment in and out contain radioactivity by detecting radioactive substances in a mode of combining the system.
The technical scheme of the invention is as follows:
technical scheme one
A portable nuclear radioactive substance detection system comprises a lithium battery, a power supply management chip, an integrated high-voltage module, a scintillation detector, a pulse amplifier, a discrimination forming module, a microprocessor, a counting/metering display module, an alarm lamp and an electric quantity display module; the output end of the lithium battery respectively provides a +12V power supply for the integrated high-voltage module, a +12V power supply and a-12V power supply for the pulse amplifier, a +5V power supply for the discrimination forming module and a +3.3V power supply for the microprocessor through the power supply management chip; the output end of the integrated high-voltage module is sequentially connected with the scintillation detector, the pulse amplifier, the screening and forming module and the microprocessor, and the output end of the microprocessor is respectively connected with the counting/metering display module, the alarm lamp and the electric quantity display module;
the power management chip, the integrated high-voltage module, the pulse amplifier, the screening and forming module and the microprocessor are all arranged on a circuit board, the lithium battery, the scintillation detector and the circuit board are arranged in the outer sleeve, the alarm lamp is arranged at the upper end of the outer sleeve, the counting/metering display module and the electric quantity display module are arranged at the upper parts of the front side and the rear side of the outer sleeve, the lower end of the outer sleeve is connected with the base through a connecting ring, the base is provided with a communication port socket, a power switch, a battery charging socket and an antenna socket, and the communication port socket, the power switch, the battery charging socket and the antenna socket are all connected with;
the scintillation detector comprises a sodium iodide scintillator and two photomultiplier tubes, and the sodium iodide scintillator is arranged between the two photomultiplier tubes; the photomultiplier is a glass vacuum device that includes a photocathode, dynode, and anode.
Further, lithium cell, scintillation detector and circuit board are installed together, the extension scintillator of scintillation detector is installed in the top, and the circuit board is installed in the intermediate position, and the lithium cell is installed in the below.
Further, the outer sleeve is of a vertical cylindrical structure, the outer diameter of the outer sleeve is 80mm, and the height of the outer sleeve is 1200 mm.
Further, still include the chassis, the chassis fixed mounting is in the base below for make the base upright and more stable.
Technical scheme two
The detection method implemented by the portable nuclear radioactive substance detection system based on the technical scheme includes the following steps:
step a, turning on a power switch, and supplying power to each module by a lithium battery;
b, detecting gamma rays by a scintillation detector, and outputting a negative pulse signal;
c, because the amplitude of the negative pulse signal is small, performing inverse amplification through a pulse amplifier;
d, shaping the amplified positive pulse signals into positive pulse signals with uniform amplitudes through a discrimination forming module;
e, the regular positive pulse signals are subjected to data processing, operation and judgment through a microprocessor, parameters are set and modified through the microprocessor, and when the count or the dosage exceeds a set threshold value, an alarm lamp gives an alarm; when the count exceeds the dosage shifting boundary value, the calibration constant is automatically changed for operation and is displayed through the counting/metering display module; and displaying the residual electric quantity of the lithium battery in real time through the electric quantity display module.
Further, the method for detecting gamma rays by the scintillation detector in the step b comprises ionizing and exciting the sodium iodide scintillator by the gamma rays incident on the sodium iodide scintillator, and losing energy by ionizing radiation; when excited atoms or molecules are de-excited, fluorescence, namely photons, is emitted, and the energy absorbed by the sodium iodide scintillator is converted into light energy; the photons are collected on a photocathode of a photomultiplier through an optical glass window; the collected photons generate photoelectrons on the photocathode through a photoelectric effect; the photoelectrons are multiplied in sequence by a dynode and an increasing accelerating electric field; the multiplied number of electrons is eventually collected by the anode and forms an observable negative polarity pulsed electrical signal on the external load resistance.
Further, the method of alarming by the alarm lamp includes assuming a local natural radioactivity maximum background count rate of nbAlarm threshold n for count rateyCalculated as follows:
calculating the alarm threshold of equivalent dose rate according to the above formula
When measured and displayed equivalent dose rate
The alarm is not started, which indicates that no radioactive substance exists; when in use
The instrument gives out sound and light alarm to indicate the existence of radioactive substances, and a response mechanism needs to be started.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a portable nuclear radioactive substance detection system and a detection method, the system adopts a column structure design integrating a scintillation detector and a power supply lithium battery, can form a detection channel with an isolation strip rail, can be rapidly deployed at an entrance and an exit of important places such as nuclear facilities, frontier ports, subways, airports, large conference activities and the like, has the functions of portability and rapid deployment, and meets the real requirement of nuclear security; the system can quickly respond to weak radioactive substances and control the occurrence of nuclear-related accidents to the maximum extent;
the method is based on the nuclear physics measurement principle, adopts a mode of combining a double-path photomultiplier sodium iodide scintillator radiation detector with multi-path pulse signal acquisition to detect radioactive substances, and carries out real-time online detection on whether people and equipment in and out contain radioactivity.
Drawings
FIG. 1 is a block diagram of the electrical components of the present invention;
FIG. 2 is a view showing the structure of the outer appearance of the present invention;
fig. 3 is a block diagram of a scintillation detector.
In the figure; the system comprises a lithium battery 1, a power management chip 2, an integrated high-voltage module 3, a scintillation detector 4, a sodium iodide scintillator 41, a photomultiplier 42, a pulse amplifier 5, a discriminator forming module 6, a microprocessor 7, a counting/metering display module 8, an alarm lamp 9, an electric quantity display module 10, an outer sleeve 11, a connecting ring 12, a base 13 and a base plate 14.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings.
Detailed description of the invention
A portable nuclear radioactive substance detection system is shown in figure 1 and comprises a lithium battery 1, a power supply management chip 2, an integrated high-voltage module 3, a scintillation detector 4, a pulse amplifier 5, a screening and forming module 6, a microprocessor 7, a counting/metering display module 8, an alarm lamp 9 and an electric quantity display module 10; the output end of the lithium battery 1 respectively provides a +12V power supply for the integrated high-voltage module 3, a +12V power supply and a-12V power supply for the pulse amplifier 5, a +5V power supply for the screening and forming module 6 and a +3.3V power supply for the microprocessor 7 through the power management chip 2; the output end of the integrated high-voltage module 3 is sequentially connected with a scintillation detector 4, a pulse amplifier 5, a screening and forming module 6 and a microprocessor 7, and the output end of the microprocessor 7 is respectively connected with a counting/metering display module 8, an alarm lamp 9 and an electric quantity display module 10;
as shown in fig. 2, the power management chip 2, the integrated high-voltage module 3, the pulse amplifier 5, the screening and forming module 6 and the microprocessor 7 are all arranged on a circuit board, the lithium battery 1, the scintillation detector 4 and the circuit board are arranged in an outer sleeve 11, the alarm lamp 9 is arranged at the upper end of the outer sleeve 11, the counting/metering display module 8 and the electric quantity display module 10 are arranged at the upper parts of the front side and the rear side of the outer sleeve 1, the lower end of the outer sleeve 11 is connected with a base 13 through a connecting ring 12, a communication port socket, a power switch, a battery charging socket and an antenna socket are arranged on the base 13, and the communication port socket, the power switch, the battery charging socket and the antenna socket are all connected with; the display parts such as the counting/metering display module 8, the electric quantity display module 10 and the like are arranged at the upper part to facilitate observation, and the operation parts such as a communication port socket, a power switch, a battery charging socket, an antenna socket and the like are arranged at the lower part to facilitate concealment;
as shown in fig. 3, the scintillation detector 4 includes a sodium iodide scintillator 41 and two photomultiplier tubes 42, the sodium iodide scintillator 41 being mounted between the two photomultiplier tubes 42; the photomultiplier tube 42 is a glass vacuum device including a photocathode, dynode, and anode.
Specifically, the screening and shaping module comprises a voltage comparator; the inverting input end of the voltage comparator is connected with an adjustable valve voltage Vy, the amplified signal which is only larger than Vy has shaping output, and no output exists when the amplified signal is smaller than Vy, so that small-amplitude noise and interference signals can be effectively removed.
Specifically, lithium cell 1, scintillation detector 4 and circuit board are installed together, scintillation detector 4's extension scintillator is installed upmost, and the circuit board is installed at the intermediate position, and lithium cell 1 installs in the below.
Specifically, the lithium battery 1 is a 12.6V lithium battery, has a capacity of 30Ah, generates the operating voltage required by each module through the power management chip 2, and can save electricity.
Specifically, the outer sleeve 11 is a vertical cylindrical structure with an outer diameter of 80mm and a height of 1200 mm.
In particular, a chassis 14 is also included, said chassis 14 being fixedly mounted under the base 13 for making the base 13 upright and more stable.
In particular, the warning lamp is fixed to the outer sleeve 11 by means of a snap.
Specifically, when the charging is turned off, the electric quantity display module 10 has 10 dark lines up and down, the top line is bright when the electric quantity display module is fully charged, the bright line gradually moves downwards along with the use time, and the bright line flickers when the electric quantity display module moves to the penultimate line, so that the alarm electric quantity is insufficient. In order to prevent the over-discharge of the battery, the charging is required to be shut down at the moment, a two-core plug of the special charger is inserted into a charging socket on the right side of the base below the stand column, the charging is started when a power plug is connected to mains supply, the charger is lighted in red, and the charger is fully charged when the red becomes green, and at least 12 hours are required.
Specifically, the microprocessor 7 is a single chip microcomputer, the sampling time is 1 second, the picture of the display component is updated in real time, and the functions of the microprocessor are as follows:
1. setting and modifying parameters, wherein the parameters comprise a calibration constant and an alarm threshold, and can be electrically erased, set and modified;
2. the operation and judgment function is that the collected count is converted into the dose by a proper calculation formula, and an alarm switch signal is given when the count or the dose exceeds a set threshold; when the count exceeds the dosage shift boundary value, the calibration constant can be automatically changed for operation and display;
3. before the dose is calibrated, the display content of the picture is count rate cps, the picture is updated once per second, the alarm threshold can be set according to a certain value which is greater than the natural background count rate, and the alarm can be given when the alarm threshold is exceeded;
4. after the dosage is calibrated, a calibration constant is set, the picture display content is equivalent dosage rate, the unit is mu Sv/h, the picture display content is updated once per second, the alarm threshold can be set according to a certain value which is greater than the natural background dosage rate, and the overthreshold can alarm;
5. the alarm function of the exceeding threshold can start sound and light to alarm simultaneously before and after calibration, and only the contents of comparison and judgment are different.
Specifically, an expansion port is reserved in the system to realize remote control and monitoring, and the method specifically comprises the steps of setting discrimination threshold and other information in monitoring software, performing data information interaction with a master control, controlling the selection of a collector threshold value and a collector channel on one hand, receiving counting rate information transmitted by a microprocessor, and analyzing and processing. In addition, the monitoring software also realizes counting rate spectral line display and historical data extraction and storage.
The system adopts the column structural design of integrating the scintillation detector 4 and the power supply lithium battery 1, can form a detection channel with the isolation strip rail, has the capability of portability and quick deployment, and is mainly applied to nuclear security in important places such as frontier port, subway, airport, large-scale conference and the like, and monitors whether the personnel in and out carry radioactive substances. It can play an important role in effectively controlling nuclear materials, preventing nuclear diffusion and preventing nuclear terrorist activities. As long as the device is deployed at the entrance and exit where people must pass, when people who carry radioactive substances such as radioactive isotopes such as 60Co and 137Cs or have nuclear medicines (such as iodine-125 particle sources and fluorine-18 contrast agents) injected in hospitals pass through the device, sound and light alarms can be given out, and data monitoring software is used for recording and storing, so that the software can be used for remotely networking and recording related information, sending out a radiation overrun sound and light alarm and outputting a monitoring report.
The detection efficiency of the system can quickly detect whether the person coming in and going out carries radioactive substances within seconds, and compared with a security inspection method of a handheld radiation dosimeter, the system is efficient and comprehensive, and professional requirements of a measurer are greatly reduced. The system design adopts a method of combining multipath pulse and coincidence counting with an ultra-long sodium iodide crystal to improve the detection efficiency, so that the system has higher detection effect on weak radioactive substances and highly shielded radioactive sources.
The device can realize the following indexes:
(1) the measuring method comprises the following steps: upright fixed-point non-contact measurement;
(2) measuring sensitive area: a semicircular sector area with a radius of 1 meter;
(3) starting time: when the time is less than 5s, the instrument starts a power supply to immediately display the counting rate or the dosage rate;
(4) energy response range: 30 keV-3 MeV;
(5) dose rate response range: 0.1 mu Sv/h-100 mu Sv/h, the counting rate corresponding to the lower limit is far more than 3 times of the standard error of the background counting rate, the detection lower limit is reliable, and the counting rate corresponding to the upper limit cannot cause the counting rate overload;
(6) incident angle response R α: < 15%;
(7) consistency of sensitivity: < 30%;
(8) alarm response time: 1s, the equipment immediately alarms after being irradiated by a source;
(9) and (3) alarm mode: intermittent/continuous audible and visual alarm;
(10) false alarm rate: under the natural environment, the false alarm frequency of continuous working for 8 hours is zero;
(11) the alarm leakage rate is as follows: when a 241Am low-energy gamma source is used for moving and irradiating at a constant speed from 0.5m to the left and right of the upright column, the dose display values exceed the alarm threshold;
(12) coefficient of variation (transient and long-term stability): the relative standard deviation is less than 5 percent;
(13) relative error: the relative error of the measurement between the upright post and the standard dosage instrument is less than 30 percent;
(14) the external dimension is as follows: standColumnBase seat
(15) Weight: 9Kg of upright column and 9Kg of base;
(16) power consumption: the static power consumption is about 80mA, and the alarm power consumption is about 200 mA.
Detailed description of the invention
A detection method implemented by the portable nuclear radioactive substance detection system according to the embodiment includes the following steps:
step a, a power switch is turned on, and the lithium battery 1 supplies power to each module;
b, detecting gamma rays by a scintillation detector 4, and outputting a negative pulse signal;
c, because the amplitude of the negative pulse signal is small, performing reverse amplification through a pulse amplifier 5;
d, shaping the amplified positive pulse signals into positive pulse signals with uniform amplitudes through a discrimination forming module 6;
e, the regular positive pulse signals are subjected to data processing, operation and judgment through the microprocessor 7, parameters are set and modified through the microprocessor 7, and when the count or the dosage exceeds a set threshold value, an alarm lamp 9 gives an alarm; when the count exceeds the dosage shifting boundary value, the calibration constant is automatically changed for operation and is displayed through the counting/metering display module 8; the remaining capacity of the lithium battery 1 is displayed in real time by the capacity display module 10.
Specifically, the method of the scintillation detector 4 detecting gamma rays in step b includes ionizing and exciting the sodium iodide scintillator 41 by gamma rays incident on the sodium iodide scintillator 41, losing energy by ionizing radiation; when excited atoms or molecules are de-excited, fluorescence, i.e. photons, are emitted, and the energy absorbed by the sodium iodide scintillator 41 is partially converted into light energy; the photons are collected onto the photocathode of the photomultiplier tube 42 through an optical glass window; the collected photons generate photoelectrons on the photocathode through a photoelectric effect; the photoelectrons are multiplied in sequence by a dynode and an increasing accelerating electric field; the multiplied number of electrons is eventually collected by the anode and forms an observable negative polarity pulsed electrical signal on the external load resistance.
In particular, the energy spectrum shapes for detecting different nuclides using sodium iodide scintillators will vary due to the different gamma photon energies of decay for each radionuclide. The energy spectrum recognition algorithm is to make alarm judgment by comparing and analyzing the energy spectrum of the detection object and the background energy spectrum, and the essence is to judge whether the detection object contains radioactive nuclide according to the change of the shape of the detection energy spectrum. In the actual measurement process, by establishing regions of interest and main characteristic regions of different nuclides, the low-energy partial pulse count and the high-energy characteristic pulse count of the characteristic regions are judged and compared under the background condition and the detection condition by using the detection energy spectrum.
Wherein CL is the low-energy pulse count of the detection energy spectrum characteristic region, CH is the high-energy pulse count of the detection energy spectrum characteristic region, DL is the low-energy pulse count of the detection energy spectrum characteristic region, and DH is the high-energy pulse count of the detection energy spectrum characteristic region. In the normal state, N is very close to 0, and when a radiation source is included, N detected by the form of energy spectrum recognition and pulse counting will not approach 0.
The method is based on the nuclear physics measurement principle, adopts a mode of combining a double-path photomultiplier sodium iodide scintillator radiation detector with a multi-path pulse signal acquisition and energy spectrum identification algorithm to detect radioactive substances, carries out real-time online detection on whether people and equipment in and out contain radioactivity, realizes software remote networking to record relevant information, sends out a radiation over-limit acousto-optic alarm and outputs a monitoring report.
In particular, when there are few incident photons, the energy resolution is poor, it is difficult to clearly see the pulse corresponding to the energy peak of the test source from the output waveform of the amplifier, and when the amplification factor is selected, the lower threshold design and width selection of the amplification factor and energy window cannot be made in the conventional manner.
The system utilizes a recursion mode, firstly sets a monitoring alarm threshold value and an amplification factor, and measures the active counting and background Compton curves by changing the channel threshold value and the channel width of the single-channel analyzer. Calculating net counts of the sources according to the background counts and the active counts, calculating ratios of the net counts to the square roots of the background counts, and making curves of the quantities varying with the lower threshold of the single track respectively. By analysis of these curves, the appropriate magnification and lower threshold and width of the energy window can be selected.
Setting an alarm threshold value as follows:
where A0 is the environmental average background and B is the influence factor, it was verified by experimental accuracy (about 2-5). The selection principle of the magnification factor and the energy window is as follows: the ratio of the active net count to the square root of the background is used for judgment, and the measurement precision is higher when the ratio is larger.
Specifically, the system measures the gamma ray counting rate, and the counting rate can be converted into the equivalent dose rate through experimental calibration and operation. The 137Cs gamma-ray source and a standard dosage instrument are adopted for comparison measurement. The radioactive source is placed at the same height from the ground as the center of the instrument scintillator, i.e., 875 mm. Measuring the average count rate n of the instrument at different distances from the source, and measuring the corresponding equivalent dose rate at the same position by using a standard dose instrument
This results in a relational array of two variables
For use as a graph or regression analysis, the calibration constants a and b can be obtained from a linear relationship according to the following formula:
for the sake of accuracy, the system can also be calibrated in sections, assuming that the counting rate at a section is no, when the measured counting rate n is not more than no, the calibration constants a1 and b1 of the first section are adopted for operation and display; and when the counting rate n is larger than or equal to no, the second section of calibration constants a2 and b2 are adopted for operation and display.
And (3) a calibration constant is obtained through experimental calibration, the set counting rate measured by the system can be automatically converted into the equivalent dose rate through operation and displayed, and the unit of the equivalent dose rate is mu Sv/h.
Specifically, the method of alarming by the alarm lamp 9 includes assuming a local natural radioactivity maximum background count rate of nbAlarm threshold n for count rateyCalculated as follows:
calculating the alarm threshold of equivalent dose rate according to the above formula
When measured and displayed equivalent dose rate
The alarm is not started, which indicates that no radioactive substance exists; when in use
The instrument gives out sound and light alarm to indicate the existence of radioactive substances, and a response mechanism needs to be started.
Detailed description of the invention
On the basis of the first embodiment, the use method implemented by the portable nuclear radioactive substance detection system comprises the following steps:
(1) placing, unpacking and taking out the system, standing at a position where the system is not easy to scrape, and adding a chassis 14 for stable placement;
(2) starting the system, pressing a power switch on a base below the outer sleeve 11, immediately displaying the natural radioactivity background equivalent dose rate by the counting/metering display module 8, displaying the residual electricity by a bright bar on the electricity quantity display module 10, and then entering a normal duty working state by the system;
(3) and (4) shutting down the power supply by pressing the power switch when the power supply is not used.
Claims (7)
1. A portable nuclear radioactive substance detection system is characterized by comprising a lithium battery (1), a power supply management chip (2), an integrated high-voltage module (3), a scintillation detector (4), a pulse amplifier (5), a screening and forming module (6), a microprocessor (7), a counting/metering display module (8), an alarm lamp (9) and an electric quantity display module (10); the output end of the lithium battery (1) respectively provides a +12V power supply for the integrated high-voltage module (3), a +12V power supply and a-12V power supply for the pulse amplifier (5), a +5V power supply for the screening and forming module (6) and a +3.3V power supply for the microprocessor (7) through the power management chip (2); the output end of the integrated high-voltage module (3) is sequentially connected with a scintillation detector (4), a pulse amplifier (5), a screening and forming module (6) and a microprocessor (7), and the output end of the microprocessor (7) is respectively connected with a counting/metering display module (8), an alarm lamp (9) and an electric quantity display module (10);
the power management chip (2), the integrated high-voltage module (3), the pulse amplifier (5), the screening and forming module (6) and the microprocessor (7) are all arranged on a circuit board, the lithium battery (1), the scintillation detector (4) and the circuit board are arranged in an outer sleeve (11), the alarm lamp (9) is arranged at the upper end of the outer sleeve (11), the counting/metering display module (8) and the electric quantity display module (10) are arranged on the upper parts of the front side and the rear side of the outer sleeve (1), the lower end of the outer sleeve (11) is connected with a base (13) through a connecting ring (12), a communication port socket, a power switch, a battery charging socket and an antenna socket are arranged on the base (13), and the communication port socket, the power switch, the battery charging socket and the antenna socket are all connected with the microprocessor (7);
the scintillation detector (4) comprises a sodium iodide scintillator (41) and two photomultiplier tubes (42), the sodium iodide scintillator (41) being mounted between the two photomultiplier tubes (42); the photomultiplier tube (42) is a glass vacuum device including a photocathode, dynode and anode.
2. A portable nuclear radioactive substance detection system according to claim 1, wherein the lithium battery (1), the scintillation detector (4) and the circuit board are mounted together, the elongated scintillator of the scintillation detector (4) is mounted uppermost, the circuit board is mounted in a middle position, and the lithium battery (1) is mounted lowermost.
3. A portable nuclear radioactive substance detection system according to claim 1, wherein the outer sleeve (11) is of a vertical cylindrical configuration with an outer diameter of 80mm and a height of 1200 mm.
4. A portable nuclear radioactive material detection system according to claim 1, further comprising a chassis (14), the chassis (14) being fixedly mounted below the base (13) for erecting and stabilizing the base (13).
5. A detection method implemented on the basis of the portable nuclear radioactive substance detection system of claims 1 to 4, comprising the steps of:
step a, turning on a power switch, and supplying power to each module by a lithium battery (1);
b, detecting gamma rays by a scintillation detector (4), and outputting a negative pulse signal;
c, because the amplitude of the negative pulse signal is small, performing reverse amplification through a pulse amplifier (5);
d, shaping the amplified positive pulse signals into positive pulse signals with uniform amplitudes through a discrimination forming module (6);
e, the regular positive pulse signals are subjected to data processing, operation and judgment through a microprocessor (7), parameters are set and modified through the microprocessor (7), and when the count or the dosage exceeds a set threshold value, an alarm lamp (9) gives an alarm; when the count exceeds the dosage shifting boundary value, the calibration constant is automatically changed for operation and is displayed through a counting/metering display module (8); the residual capacity of the lithium battery (1) is displayed in real time through the capacity display module (10).
6. The portable nuclear radioactive substance detection method according to claim 5, wherein the method of detecting gamma rays by the scintillation detector (4) in the step b includes ionizing and exciting the sodium iodide scintillator (41) by gamma rays incident on the sodium iodide scintillator (41), and energy is lost by ionizing radiation; when excited atoms or molecules are de-excited, fluorescence is emitted, namely photons, and the energy absorbed by the sodium iodide scintillator (41) is partially converted into light energy; the photons are collected on the photocathode of the photomultiplier tube (42) through the optical glass window; the collected photons generate photoelectrons on the photocathode through a photoelectric effect; the photoelectrons are multiplied in sequence by a dynode and an increasing accelerating electric field; the multiplied number of electrons is eventually collected by the anode and forms an observable negative polarity pulsed electrical signal on the external load resistance.
7. A portable nuclear radioactive substance detection method according to claim 6, wherein the alarm by the alarm lamp (9) includes assuming a local natural radioactivity maximum background count rate of nbAlarm threshold n for count rateyCalculated as follows:
calculating the alarm threshold of equivalent dose rate according to the above formula
When measured and displayed equivalent dose rate
The alarm is not started, which indicates that no radioactive substance exists; when in useThe instrument gives out sound and light alarm to indicate the existence of radioactive substances, and a response mechanism needs to be started.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113156487A (en) * | 2021-04-27 | 2021-07-23 | 中国核动力研究设计院 | Method for adjusting discrimination threshold of pulse measurement circuit in program control manner |
| CN114660647A (en) * | 2022-04-11 | 2022-06-24 | 中国人民解放军69007部队 | Novel portable nuclear radiation survey instrument |
| CN117908082A (en) * | 2024-01-22 | 2024-04-19 | 营口世纪电子仪器股份有限公司 | Throwing type radiation detection device |
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2019
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113156487A (en) * | 2021-04-27 | 2021-07-23 | 中国核动力研究设计院 | Method for adjusting discrimination threshold of pulse measurement circuit in program control manner |
| CN114660647A (en) * | 2022-04-11 | 2022-06-24 | 中国人民解放军69007部队 | Novel portable nuclear radiation survey instrument |
| CN117908082A (en) * | 2024-01-22 | 2024-04-19 | 营口世纪电子仪器股份有限公司 | Throwing type radiation detection device |
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