CN111913205A - Nuclear emergency multifunctional portable radiation monitoring system and monitoring method - Google Patents

Abstract

The invention discloses a nuclear emergency multifunctional portable radiation monitoring system and a monitoring method, wherein the monitoring method comprises the following steps: the device comprises a detection module and a data processing and control module; the detection module is bidirectionally connected with the data processing and control module; the detection module comprises a G-M counting tube, a NaI detector and a 3He neutron detection counting tube; the data processing and control module comprises a detector selection unit, a multichannel pulse amplitude analyzer and a metering conversion unit; the invention can simultaneously measure two data of dose rate and gamma energy spectrum, and broadens the dose rate range, thereby increasing the application range of the system.

Description

A nuclear emergency multifunctional portable radiation monitoring system and monitoring method

technical field

The invention relates to the technical field of nuclear radiation monitoring, in particular to a nuclear emergency multifunctional portable radiation monitoring system and a monitoring method.

Background technique

With the development of nuclear technology, the utilization of nuclear technology has gradually entered people's lives, and more and more projects are related to nuclear technology, such as nuclear power industry, radiological medicine, radiation inactivation modification, etc. But we should be aware that while nuclear technology can benefit us, it can also harm human life. The number of radioactive sources used by medical, industrial, agricultural and other departments in my country is large, the cycle is long, and the distribution is scattered, which is very difficult to manage. Although the relevant government departments have continuously strengthened the management measures of radioactive sources, there are still radioactive source accidents. For example, a series of nuclear safety incidents such as the loss of the source used in industrial flaw detection and the neutron source used in oil logging, the untimely treatment of radioactive tailings, and the radioactive leakage caused by nuclear accidents in nuclear facilities. Therefore, while using nuclear technology, the detection and monitoring of radiation environment must also be strengthened. In order to protect the public and the environment, it is very important to improve the emergency response capability of radiation accidents, and it will become extremely important to explore more advanced technologies to improve nuclear radiation detection instruments.

The magnitude of radioactivity (dose rate) and the type of radioactivity (X, γ, n) are the two most concerned parameters in radioactivity assessment. my country's environmental protection departments generally use single-function detectors to carry out related work, and analysis of radiation fields often requires more. All kinds of detectors work together at the same time. After measuring a variety of data, the actual situation of the entire radiation site is analyzed, which will cause a certain information lag in some sudden nuclear accidents, which is not conducive to the rapid control and disposal of nuclear accidents.

Therefore, how to develop a nuclear emergency multifunctional portable radiation monitoring system and a monitoring method that can not only detect the magnitude of nuclear radiation but also accurately detect the type of nuclear radiation is an urgent problem for those skilled in the art to solve.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a nuclear emergency multifunctional portable radiation monitoring system and monitoring method, the purpose of which is to detect the magnitude of nuclear radiation and accurately detect the type of nuclear radiation.

In order to achieve the above object, the present invention adopts the following technical solutions:

A nuclear emergency multifunctional portable radiation monitoring system, comprising: a detection module and a data processing and control module; the detection module and the data processing and control module are bidirectionally connected;

The detection module includes a G-M counter tube, a NaI detector and a 3He neutron detection counter tube;

Wherein, the G-M counter tube and the NaI detector are used for radiation detection at the high-energy section and the low-energy end of the radiation dose, respectively, and the 3He neutron detection counter tube is used for neutron dose detection;

The data processing and control module includes a detector selection unit, a multi-channel pulse amplitude analyzer and a metering conversion unit;

The detector selection unit is respectively connected with the G-M counter tube and the NaI detector, and is used to control the gating of the G-M counter tube and the NaI detector in the detection module to realize the G-M counting Switching of the tube and the NaI detector;

The multi-channel pulse amplitude analyzer is connected to the NaI detector for acquiring an energy spectrum, and comparing the acquired energy spectrum with a standard energy spectrum to determine the type of radionuclide that produces current radiation;

The dose conversion unit is respectively connected with the multi-channel pulse amplitude analyzer, the G-M counter tube and the 3He neutron detection counter tube, and is used for obtaining the corresponding air absorption dose rate and neutron radiation dose through conversion.

Preferably, the detector selection unit includes a memory, a range discriminator and a gating switch;

A count value threshold Ns is preset in the memory, wherein the count value threshold Ns belongs to the cross range of the G-M counter tube and the NaI detector range;

The range discriminator is connected with the memory and the gating switch, and is used for comparing the pulse count N0 obtained by the pre-gated G-M counter tube with the count value threshold Ns;

The gating switch controls the on-off of the G-M counter tube and the NaI detector according to the comparison result of the range discriminator.

Preferably, the data processing and control module further includes an amplifier circuit, and the amplifier circuit is respectively connected to the output ends of the NaI detector and the 3He neutron detection counter tube, and is used for amplifying the pulse signal generated by the detection. .

Preferably, the detection module further includes a temperature sensor, and the temperature sensor is used to acquire the ambient temperature in real time.

Preferably, the data processing and control module further includes an energy spectrum stabilization unit; the energy spectrum stabilization unit is respectively connected with the multi-channel pulse amplitude analyzer and the temperature sensor, and is used for completing the energy spectrum according to the real-time ambient temperature. Spectral address correction, so that the energy spectrum tends to be stable under temperature changes.

The beneficial effects of adopting the above technical scheme are:

The G(E) fitting of the energy spectrum and the dose is used to correct the low-energy over-response problem of the ray. Combined with temperature compensation, the detection efficiency of the instrument for weak radioactivity and the accuracy of the low dose are improved.

Preferably, it also includes a power supply module, the power supply module includes a high-voltage power supply and a low-voltage power supply, the high-voltage power supply is used to supply power to the detection module, and the low-voltage power supply supplies power to the data processing and control module.

Preferably, it also includes a data transmission module, the data transmission module is connected with the data processing and control module, and data interaction with the upper computer is realized through the data transmission module.

A monitoring method for a nuclear emergency multifunctional portable radiation monitoring system, comprising the following steps:

S1. The detection module performs real-time detection, in which the G-M counter tube and the NaI detector respectively perform radiation detection on the high-energy section and the low-energy end of the radiation dose, and the 3He neutron detection counter tube detects the neutron dose and detects the detected neutron dose. The results are sent to the data processing and control module;

S2. the detector selection unit controls the gating of the G-M counter tube and the NaI detector;

When the G-M counter tube is gated, the pulses are counted, and the obtained result is sent to the metering conversion unit, and the metering conversion unit converts the pulse count rate into the air absorbed dose rate;

When the NaI detector is gated, the pulses are counted, and the obtained results are sent to a multi-channel pulse amplitude analyzer, and the multi-channel pulse amplitude analyzer obtains the energy spectrum, and uses the energy window discrimination method to The energy spectrum is compared with the standard energy spectrum to determine the type of radionuclide that produces the current radiation; the dose conversion unit obtains the energy spectrum, and calculates the corresponding air absorbed dose rate result through the G(E) function;

The 3He neutron detection and counting tube sends the detected results to the dose conversion unit to obtain the neutron radiation dose detection results.

Preferably, the specific method for the detector selection unit described in S2 to control the gating of the G-M counter tube and the NaI detector is:

Strobe the G-M counter tube, obtain the count value N0, and compare the count value N0 with the count value threshold Ns;

If N0≥Ns, continue gating the G-M counter tube through the gating switch to obtain the count value N1, where N1 is the final count value;

If N0<Ns, turn off the G-M counter tube through the gating switch, and then gating the NaI detector.

As can be seen from the above technical solutions, compared with the prior art, the present invention discloses and provides a nuclear emergency multifunctional portable radiation monitoring system and monitoring method. , to realize the radiation detection of X, γ, and n rays at the same time, and the radiation dose rate can be obtained accurately and quickly; secondly, because the G-M tube, NaI, and 3He tube two kinds of radiation detectors due to the existence of dead time The working characteristics are relatively Limitation, the present invention automatically selects NaI detector and GM counter tube for detection by controlling it in low and high dose rate environments, and the two complement each other so that the system can simultaneously measure both the dose rate and energy spectrum data, and also measure the dose. The frequency range has been widened, which has increased the scope of application of the system; in addition, the energy spectrum can be quickly obtained through the multi-channel pulse amplitude analyzer, and the types of radionuclides can be further quickly obtained by comparing the energy spectrum with the standard energy spectrum. Accurately and effectively achieve wide-range coverage of dose rates and fast and effective identification of commonly used nuclides, and the radiation monitoring system has a simple structure and a small volume after forming a monitoring instrument, which can guide related radiation practitioners more conveniently, quickly, accurately and safely. Personnel to carry out related work, so that detection equipment and technology are not only applicable to the scene of a sudden nuclear accident, but also to various places that require radiation monitoring.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the provided drawings without creative work.

1 is a schematic diagram of the overall structure of a nuclear emergency multifunctional portable radiation monitoring system provided by the present invention;

2 is a schematic flowchart of a monitoring method of a nuclear emergency multifunctional portable radiation monitoring system provided by the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The embodiment of the invention discloses a nuclear emergency multifunctional portable radiation monitoring system, comprising: a detection module and a data processing and control module; the detection module and the data processing and control module are bidirectionally connected;

The detection module includes G-M counter tube, NaI detector and 3He neutron detection counter tube;

Among them, the G-M counter tube and the NaI detector are used for radiation detection at the high-energy section and the low-energy end of the radiation dose, respectively, and the 3He neutron detection counter tube is used for neutron dose detection;

The data processing and control module includes a detector selection unit, a multi-channel pulse amplitude analyzer and a measurement conversion unit;

The detector selection unit is respectively connected with the G-M counter tube and the NaI detector, and is used to control the gating of the G-M counter tube and the NaI detector in the detection module, so as to realize the switching of the G-M counter tube and the NaI detector;

The multi-channel pulse amplitude analyzer is connected with the NaI detector to obtain the energy spectrum, and the obtained energy spectrum is compared with the standard energy spectrum to determine the type of radionuclide that produces the current radiation;

The dose conversion unit is respectively connected with the multi-channel pulse amplitude analyzer, the G-M counter tube and the 3He neutron detection counter tube, and is used to obtain the corresponding air absorbed dose rate and neutron radiation dose through conversion.

In order to further implement the above technical solution, the detector selection unit includes a memory, a range discriminator and a gate switch;

The count value threshold Ns is preset in the memory, and the count value threshold Ns belongs to the cross range of the G-M counter tube and the NaI detector range;

The range discriminator is connected with the memory and the gating switch, and is used to compare the pulse count N0 obtained by the pre-gated G-M counter tube with the count value threshold Ns;

The gating switch controls the on-off of the G-M counter tube and the NaI detector according to the comparison result of the range discriminator.

In order to further implement the above technical solution, the data processing and control module further includes an amplifier circuit, which is respectively connected to the output ends of the NaI detector and the 3He neutron detection counter tube for amplifying the pulse signal generated by the detection.

In order to further implement the above technical solution, the detection module further includes a temperature sensor, and the temperature sensor is used to acquire the ambient temperature in real time.

In order to further implement the above technical solution, the data processing and control module further includes an energy spectrum stabilization unit; the energy spectrum stabilization unit is respectively connected with the multi-channel pulse amplitude analyzer and the temperature sensor, and is used for completing the correction of the energy spectrum channel address according to the real-time ambient temperature. , so that the energy spectrum tends to be stable under temperature changes.

It should be noted:

The working temperature range of the gamma spectrometer in the outdoor environment is generally -20 to 50 °C. NaI scintillation crystals and photomultiplier tubes in NaI detectors are temperature-sensitive devices. Any temperature change will cause changes in the detector output, resulting in a shift in the energy peak position, which makes it difficult to analyze energy spectrum data and identify nuclides.

探测器进行实验，得到各温度下的γ能谱进行存储。并根据所得不同温度下的γ能谱，记录下每个能谱中X射线峰位、光电峰的道数值，拟合其道址随温度的变化曲线。在稳谱中可以用一条斜率为Gain、零点为offset的直线作为能量刻度曲线，通过测量¹³⁷Cs的两个参考峰位进行能量刻度。最后采用137Cs作为参考源首先测量其32KeV特征X射线峰位ch32KeV和662KeV特征γ射线峰位ch622KeV然后进行能量刻度公式1和公式2，再根据不同时刻标定的能量刻度曲线和初始能量刻度曲线把测量道址ch测量校正到校正道址ch校正公式3：In this example, the ¹³⁷ Cs radioactive source was used as the calibration source, and the calibration was performed at different temperatures (-20 to 30°C, 5°C/interval) in a high and low temperature experimental box.

The detector performs experiments to obtain the γ energy spectrum at each temperature for storage. And according to the obtained γ energy spectrum at different temperatures, the X-ray peak position and the channel value of the photoelectric peak in each energy spectrum were recorded, and the change curve of the channel position with temperature was fitted. In the stable spectrum, a straight line with a slope of Gain and a zero point of offset can be used as the energy calibration curve, and the energy calibration can be performed by measuring the two reference peak positions of ¹³⁷ Cs. Finally, using 137Cs as the reference source, firstly measure its 32KeV characteristic X-ray peak position ch32KeV and 662KeV characteristic γ-ray peak position ch622KeV, then carry out the energy calibration formula 1 and formula 2, and then measure the measurement according to the energy calibration curve and the initial energy calibration curve at different times. The track address ch is measured and corrected to the corrected track address ch. Correction formula 3:

Gain=662-32/(ch622KeV－ch32KeV)KeV Formula 1

offset=32×ch622KeV－662×ch32KeV/(ch622KeV－ch32KeV)KeV Formula 2

chCorrection=1/Gain0(Gain(n)×chMeasurement+offset(n)-offset(0)) Equation 3

Finally, the correction coefficient curves at different temperatures are obtained according to the temperature drift curve, and the correction function is written into the host computer program. When the system is working, the host computer obtains the temperature sensor value in real time and selects the correction coefficient corresponding to the temperature, and automatically completes the correction of the gamma energy spectrum, so that the energy spectrum tends to be stable under temperature changes.

In order to further implement the above technical solution, a power supply module is also included. The power supply module includes a high-voltage power supply and a low-voltage power supply. The high-voltage power supply is used for powering the detection module, and the low-voltage power supply is used for powering the data processing and control module.

In order to further implement the above technical scheme, a data transmission module is also included, the data transmission module is connected with the data processing and control module, and data interaction with the upper computer is realized through the data transmission module.

A monitoring method for a nuclear emergency multifunctional portable radiation monitoring system, comprising the following steps:

S1. The detection module performs real-time detection, in which the G-M counter tube and the NaI detector respectively perform radiation detection on the high-energy section and the low-energy end of the radiation dose, and the 3He neutron detection counter tube detects the neutron dose and detects the detected neutron dose. The results are sent to the data processing and control module;

S2. The detector selection unit controls the gating of the G-M counter tube and the NaI detector;

When the G-M counter tube is gated, the pulses are counted, and the obtained result is sent to the metering conversion unit, and the metering conversion unit converts the pulse count rate into the air absorbed dose rate;

When the NaI detector is gated, the pulses are counted, and the obtained results are sent to the multi-channel pulse amplitude analyzer, and the multi-channel pulse amplitude analyzer obtains the energy spectrum. The energy spectrum comparison determines the type of radionuclide that produces the current radiation; the dose conversion unit obtains the energy spectrum, and calculates the corresponding air absorbed dose rate result through the G(E) function;

The 3He neutron detection and counting tube sends the detected results to the dose conversion unit to obtain the neutron radiation dose detection results.

It should be noted:

The energy window discrimination method divides the energy segment into several energy windows according to the needs. By reasonably setting the energy upper limit and energy lower limit of each energy window, and taking all the counts of rays within this range as the main contribution of the energy characteristic peak, The nuclide information can be judged by direct comparison, and different energy windows can be added for nuclide analysis as needed.

The energy value of each radionuclide is within a certain range, and its position in the entire energy spectrum is relatively fixed. Usually, the energy range of the radionuclide in contact is 30keV-3MeV. Usually, the energy range is divided into 2 according to the size of the resolution. The integer multiple of ¹⁰ is the integer multiple of 1024 (if it is divided by 1024, the track width is 3Mev/1024=3keV,) The energy of some nuclides is known, such as the energy of ¹³¹ I is 365.4keV, the energy of ¹³⁷ Cs is 661.7keV, ⁶⁰ Co is 1173.2keV, and ²³⁸ U is 2680keV. When measuring a specific nuclide, only a certain range of energy can be observed. This certain range is the energy window. If it is found that the energy range of a certain nuclide falls within Within the range of the energy window, the radionuclide can be determined.

The G(E) function is not only related to the corresponding counts of the γ energy spectral location, but also to the corresponding energy, so the contribution of each channel count and energy to the air absorbed dose rate is different. Therefore, the G(E) function method is a method of calculating the air absorbed dose rate by using the γ energy spectrum obtained by measurement and performing weighted integration processing on the counts.

This functional relationship can be described by the following formula:

D _air is the air absorbed dose rate; T is the measurement time; N(E) is the γ energy spectrum measured in the T time; G(E) is the weight function form of the γ energy spectrum. The most commonly used form of the G(E) function is as follows:

In formula (1.2): K is the order of the function; Ak is the undetermined coefficient; E is the energy corresponding to the γ energy spectrum location. When using the standard radionuclide point source to calibrate the HPGeγ spectrometer, for different standard radioactivity The nuclide point source j has:

Then, the following formula can be obtained:

E _i is the energy corresponding to the i-th channel of the γ energy spectrum; J is the number of standard radionuclide point sources; N _ji is the corresponding count on the i-th channel of the j-th nuclide energy spectrum. Therefore, this method uses a gamma spectrometer to measure the standard radionuclide point source, constructs a function matrix equation, and then uses the least squares method or the conjugate gradient method to solve the value of the undetermined coefficient AK. , and calculate the corresponding air absorbed dose rate result.

In order to further implement the above technical solution, the specific method that the detector selection unit in S2 controls the gating of the G-M counter tube and the NaI detector is:

Gating the G-M counter tube, obtaining the count value N0, and comparing the count value N0 with the count value threshold Ns;

If N0≥Ns, continue gating the G-M counter tube through the gating switch to obtain the count value N1, which is the final count value;

If N0<Ns, turn off the G-M counter tube through the gating switch, and then gating the NaI detector.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant part can be referred to the description of the method.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. A nuclear emergency multifunctional portable radiation monitoring system, characterized in that, comprising: a detection module and a data processing and control module; the detection module and the data processing and control module are bidirectionally connected; The detection module includes a G-M counter tube, a NaI detector and a 3He neutron detection counter tube; Wherein, the G-M counter tube and the NaI detector are used for radiation detection at the high-energy section and the low-energy end of the radiation dose, respectively, and the 3He neutron detection counter tube is used for neutron dose detection; The data processing and control module includes a detector selection unit, a multi-channel pulse amplitude analyzer and a metering conversion unit; The detector selection unit is respectively connected with the G-M counter tube and the NaI detector, and is used to control the gating of the G-M counter tube and the NaI detector in the detection module to realize the G-M counting Switching of the tube and the NaI detector; The multi-channel pulse amplitude analyzer is connected to the NaI detector for acquiring an energy spectrum, and comparing the acquired energy spectrum with a standard energy spectrum to determine the type of radionuclide that produces current radiation; The dose conversion unit is respectively connected with the multi-channel pulse amplitude analyzer, the G-M counter tube and the 3He neutron detection counter tube, and is used for obtaining the corresponding air absorption dose rate and neutron radiation dose through conversion. 2. A nuclear emergency multifunctional portable radiation monitoring system according to claim 1, wherein the detector selection unit comprises a memory, a range discriminator and a gating switch; A count value threshold Ns is preset in the memory, wherein the count value threshold Ns belongs to the cross range of the G-M counter tube and the NaI detector range; The range discriminator is connected with the memory and the gating switch, and is used for comparing the pulse count N0 obtained by the pre-gated G-M counter tube with the count value threshold Ns; The gating switch controls the on-off of the G-M counter tube and the NaI detector according to the comparison result of the range discriminator. 3. A nuclear emergency multifunctional portable radiation monitoring system according to claim 1, wherein the data processing and control module further comprises an amplifier circuit, the amplifier circuit is respectively connected with the NaI detector and the The output end of the 3He neutron detection counter tube is connected to amplify the pulse signal generated by the detection. 4 . The nuclear emergency multifunctional portable radiation monitoring system according to claim 1 , wherein the detection module further comprises a temperature sensor, and the temperature sensor is used to acquire the ambient temperature in real time. 5 . 5. The nuclear emergency multifunctional portable radiation monitoring system according to claim 4, wherein the data processing and control module further comprises an energy spectrum stabilization unit; The pulse amplitude analyzer is connected with the temperature sensor, and is used for completing the correction of the energy spectrum channel address according to the real-time ambient temperature, so that the energy spectrum tends to be stable under temperature changes. 6 . The nuclear emergency multifunctional portable radiation monitoring system according to claim 1 , further comprising a power supply module, wherein the power supply module comprises a high-voltage power supply and a low-voltage power supply, and the high-voltage power supply is used for the detection The module supplies power, and the low-voltage power supply supplies power to the data processing and control module. 7 . The nuclear emergency multifunctional portable radiation monitoring system according to claim 1 , further comprising a data transmission module, the data transmission module is connected with the data processing and control module, and the data transmission module is connected with the data processing and control module. 8 . The module realizes data interaction with the host computer. 8. A monitoring method for a nuclear emergency multifunctional portable radiation monitoring system, characterized in that it comprises the following steps: S1. The detection module performs real-time detection, in which the G-M counter tube and the NaI detector respectively perform radiation detection on the high-energy section and the low-energy end of the radiation dose, and the 3He neutron detection counter tube detects the neutron dose and detects the detected neutron dose. The results are sent to the data processing and control module; S2. the detector selection unit controls the gating of the G-M counter tube and the NaI detector; When the G-M counter tube is gated, the pulses are counted, and the obtained result is sent to the metering conversion unit, and the metering conversion unit converts the pulse count rate into the air absorbed dose rate; When the NaI detector is gated, the pulses are counted, and the obtained results are sent to a multi-channel pulse amplitude analyzer, and the multi-channel pulse amplitude analyzer obtains the energy spectrum, and uses the energy window discrimination method to The energy spectrum is compared with the standard energy spectrum to determine the type of radionuclide that produces the current radiation; the dose conversion unit obtains the energy spectrum, and calculates the corresponding air absorbed dose rate result through the G(E) function; The 3He neutron detection and counting tube sends the detected results to the dose conversion unit to obtain the neutron radiation dose detection results. 9. The monitoring method of a nuclear emergency multifunctional portable radiation monitoring system according to claim 8, wherein the detector selection unit described in S2 selects the G-M counter tube and the NaI detector. The specific method of control is as follows: Strobe the G-M counter tube, obtain the count value N0, and compare the count value N0 with the count value threshold Ns; If N0≥Ns, continue gating the G-M counter tube through the gating switch to obtain the count value N1, where N1 is the final count value; If N0<Ns, turn off the G-M counter tube through the gating switch, and then gating the NaI detector.

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