Explosion-proof radioactive gas radiation detector

Abstract

The invention provides an explosion-proof radioactive gas radiation detector which comprises a crystal shell and a crystal packaging shell, the crystal shell and the crystal packaging shell are connected through a flame-retardant sealing ring, a sodium iodide crystal is arranged in the crystal shell, one end of the sodium iodide crystal is in contact with the crystal shell, the other end of the sodium iodide crystal is provided with a photomultiplier tube, and the photomultiplier tube is connected with the crystal shell. The photomultiplier tube is arranged in the photomultiplier tube housing, one end face of the photomultiplier tube is provided with a photomultiplier tube pressing sheet, the photomultiplier tube pressing sheet is connected with the pcb supporting plate, the pcb supporting plate is provided with a plurality of circuit boards which are arranged at intervals, and the circuit boards are connected through copper columns. And secondly, multi-channel processing can be carried out on data, real-time control and parameter modification (multi-channel operation gain, multi-channel operation high voltage and measurement period) can be realized on multi-channel measurement, information processing is fast, and quick response can be realized.

Description

Technical Field

[0001] The invention relates to the field of radiation protection, in particular to an explosion-proof radioactive gas radiation detector. Background Art

[0002] The gas sampling radiation monitoring device is a widely used type of radiation detector. The basic principle is to use a vacuum pump or fan to extract the gas to be tested from a harsh environment or an area that is difficult for people to access to a designated area through a sampling pipe, and then use a special radiation detector to measure the content of radioactive substances in the sampled gas in a mild environment to monitor whether radioactive contamination occurs in the area to be tested, thereby determining whether there is any abnormality in the nuclear process (including radiation) related to the area to be tested and whether the workers are likely to be harmed by radiation.

[0003] The sodium iodide detector converts the gamma photon radiation signal emitted by the gas in the measured pipeline into an electrical signal and outputs it to the electronic component. The electronic component amplifies, processes and converts the received electrical signal into a digital signal, and finally transmits the detector signal to the local radiation processing unit. The local radiation processing unit collects, stores and processes the digital signal to provide the radioactivity concentration data at the location of the detector.

[0004] Because the measuring pipeline contains flammable gas, explosion-proof treatment is required. Generally, the gas is first subjected to explosion-proof treatment (gas concentration treatment, etc.) and then measured, which is a complicated process. Secondly, the current detector data acquisition and processing is a one-to-one relationship, with low processing efficiency and inability to respond quickly. Summary of the invention

[0005] The present invention is aimed at the deficiencies in the background technology and provides an explosion-proof radioactive gas radiation detector. The new structure is explosion-proof and can perform multi-channel processing on data, realize real-time control and parameter modification (multi-channel operation gain, multi-channel operation high voltage, measurement cycle) of multi-channel measurement, and has fast information processing and rapid response.

[0006] The objective of the present invention is achieved through the following technical measures: an explosion-proof radioactive gas radiation detector, comprising a crystal shell and a crystal packaging shell, the crystal shell and the crystal packaging shell are connected by a flame-retardant sealing ring, a sodium iodide crystal is arranged in the crystal shell, one end of the sodium iodide crystal is in contact with the crystal shell, and the other end is arranged with a photomultiplier tube, the photomultiplier tube is arranged in a photomultiplier tube cover, one end face of the photomultiplier tube is provided with a photomultiplier tube pressing sheet, the photomultiplier tube pressing sheet is connected to a PCB support plate, a plurality of mutually spaced circuit boards are arranged on the PCB support plate, and the circuit boards are connected by copper columns.

[0007] Furthermore, the rear end of the sodium iodide crystal is connected to a photomultiplier tube via a light guide.

[0008] Furthermore, photomultiplier tube pressure rings are provided on both sides of the photomultiplier tube.

[0009] Furthermore, the crystal housing is made of stainless steel.

[0010] Furthermore, the circuit board includes a voltage divider circuit board, a preamplifier board, a multi-channel, and a communication board.

[0011] Furthermore, the voltage divider circuit board, preamplifier board, multi-channel, and communication board are connected in sequence from left to right through lines.

[0012] Furthermore, the spacing between the voltage divider circuit board, the preamplifier board, the multi-channel and the communication board is greater than 15 mm.

[0013] Furthermore, a blue LED lamp is arranged between the communication board and the voltage divider circuit board.

[0014] A plurality of mutually spaced circuit boards are arranged on the PCB support board of the present invention, and the circuit boards are connected to each other through copper pillars. The intervals between the voltage divider circuit board, the preamplifier board, the multi-channel and the communication board are greater than 15 mm, thereby increasing the wiring cavity and ensuring sufficient size, which is convenient for reliable connection of the wires. The crystal housing is made of stainless steel, which plays an explosion-proof role.

[0015] The voltage divider board of the present invention provides working voltage for the photomultiplier tube, and inputs the signal into the rear-end preamplifier circuit after completing the photoelectric signal conversion and amplification; after the signal is preamplified with a certain gain, it directly enters the multi-channel for collection; the ARM processing board analyzes and processes the gamma energy spectrum collected by the multi-channel, and adjusts the soft gain of the multi-channel when necessary to stabilize the spectrum; the multi-channel and ARM data processing boards are designed on different circuit boards to form a front-end processing unit, which is arranged at the output end of the detector; the front-end processing unit communicates with the local radiation processing unit or the debugging computer through the RS485 / RS232 interface, and transmits the measured count rate of the interval of interest, energy spectrum information, equipment status and other information to the local radiation processing unit (LRP) or the debugging computer for processing and display, and can perform multi-channel processing on the data, can realize real-time control and parameter modification (multi-channel operation gain, multi-channel operation high voltage, measurement cycle) of the multi-channel measurement, has fast information processing, and can respond quickly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a cross-sectional view of the structure of the explosion-proof radioactive gas radiation detector of the present invention;

[0017] Figure 2 It is a schematic diagram of the circuit and signal processing of explosion-proof radioactive gas radiation detector;

[0018] Figure numerals: crystal housing 1, light guide 2, crystal pressure ring 3, photomultiplier tube cover 4, photomultiplier tube pressure sheet 5, photomultiplier tube pressure ring 6, hexagon socket screw 7, crystal packaging shell 8, PCB support plate 9, cross recessed countersunk screw 10, crystal housing end face 11, sodium iodide crystal 12, photomultiplier tube 13, circuit board 14, explosion-proof joint 15, sealing ring 16, single-head copper column 17, 18, 19, cross pan head screw 20. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] like Figure 1 As shown, an explosion-proof radioactive gas radiation detector includes a crystal housing 1 and a crystal packaging shell 8, the crystal housing 1 and the crystal packaging shell 8 are connected by a flame retardant sealing ring 16, a sodium iodide crystal 12 is arranged in the crystal housing 1, one end of the sodium iodide crystal is in contact with the crystal housing 1 and a crystal pressure ring 3 is arranged, and the other end is provided with a photomultiplier tube 13, the photomultiplier tube 13 is arranged in a photomultiplier tube cover 4, one end face of the photomultiplier tube 13 is provided with a photomultiplier tube pressing sheet 5, the photomultiplier tube pressing sheet 5 is connected to a pcb support plate 9, a plurality of mutually spaced circuit boards 14 are arranged on the pcb support plate 9, and the circuit boards 14 are connected by copper pillars (17 / 18 / 19). The rear end of the sodium iodide crystal is connected to the photomultiplier tube 13 through a light guide 2. Photomultiplier tube pressing rings 6 are also arranged on both sides of the photomultiplier tube 13. The crystal housing 1 is made of stainless steel. The rest also includes connecting and fixing parts such as hexagon socket screws 7, cross recessed countersunk screws 10, cross pan head screws 20, etc. An explosion-proof joint 15 is also provided outside to connect with the end face 11 of the crystal housing.

[0021] The detection principle of the present invention is as follows: Sodium iodide crystal is an inorganic scintillating crystal. When irradiated by gamma rays, the incident gamma rays will lose energy in the scintillator, causing ionization and excitation of the scintillator. The de-excitation of the excited atoms will emit visible light of about 410nm. After the light transmission process, the photon hits the cathode of the photomultiplier tube, and the photoelectric effect occurs to generate photoelectrons. The photoelectrons are multiplied and focused in the photomultiplier tube, and finally enter the signal processing circuit through the anode of the photomultiplier tube to form an electrical pulse signal. This pulse is output by the preamplifier after being formed and recorded and analyzed in multiple channels.

[0022] When radioactive gas flows through the measuring pipe section, some particles decay and emit gamma photons. These gamma photons pass through the outer wall of the pipe and the detector shell and enter the sodium iodide crystal to generate pulse counts. This count is proportional to the activity concentration of the solution. The greater the gas activity concentration, the more pulse counts are generated. The gamma ray count rate measured by the detector has the following relationship with the activity concentration:

[0023] n=q·V·k1·k2

[0024] Where:

[0025] q is the activity concentration of low-level gas in the measuring pipeline, Bq / m 3 ;

[0026] V is the volume of the measuring pipe, m 3 ;

[0027] k1 is the gamma-ray emissivity factor;

[0028] k2 is the detector detection efficiency factor;

[0029] n is the gamma radiation count rate at the measurement location, s -1 .

[0030] Among them, the density of sodium iodide crystal is 3.67g / cm 3 The rear end of the crystal is coupled to the photomultiplier tube through a coupling agent to reduce light loss. The rear end of the photomultiplier tube is connected to the voltage divider circuit and circuit board to complete power supply and signal processing. The shell is made of stainless steel with a density of 7.8kg / cm 3 , the top surface is 1.5mm thick, and the side surface of the cylinder is 2mm thick. The PCB support plate of the present invention is provided with a plurality of mutually spaced circuit boards, and the circuit boards are connected by copper pillars. The intervals between the voltage divider circuit board, the preamplifier board, the multichannel, and the communication board are greater than 15mm, which increases the wiring cavity and ensures sufficient size, which is convenient for reliable connection of the wire. The whole detector is sealed and waterproof, moisture-proof, and salt spray-proof.

[0031] like Figure 2 As shown, the circuit board includes a voltage divider circuit board, a preamplifier board, a multi-channel, and a communication board. The voltage divider circuit board, the preamplifier board, the multi-channel, and the communication board are connected in sequence from left to right through a line. The interval between the voltage divider circuit board, the preamplifier board, the multi-channel, and the communication board is greater than 15 mm.

[0032] The equipment uses a blue light LED inspection source for source inspection. The blue light LED lamp is arranged in the voltage divider circuit above the photomultiplier tube, and a lead is connected from the ARM processing board (the ARM processing board is the above-mentioned communication board) to it so that the blue light LED lamp is turned on.

[0033] In one embodiment, the detector voltage divider provides a working voltage for the photomultiplier tube, and after completing the photoelectric signal conversion and amplification, the signal is input into the back-end preamplifier circuit; after the signal is preamplified with a certain gain, it directly enters the multi-channel for collection; the ARM processing board analyzes and processes the gamma energy spectrum collected by the multi-channel, and adjusts the soft gain of the multi-channel when necessary to stabilize the spectrum; the multi-channel and ARM data processing boards are designed on different circuit boards to form a front-end processing unit, which is arranged at the output end of the detector; the front-end processing unit communicates with the local radiation processing unit or the debugging computer through the RS485 / RS232 interface, and transmits the measured count rate of the interval of interest, energy spectrum information, equipment status and other information to the local radiation processing unit (LRP) or the debugging computer for processing and display.

[0034] The gain adjustment is sent to multiple channels by the ARM data processing board. The gain is the software gain of the multiple channels. The default value is the debugging end parameter and the adjustment range is 1-32768.

[0035] The energy spectrum, multi-channel high voltage, gain and other information are transmitted between the multi-channel and ARM data processing boards through TTL communication. The energy spectrum consists of 2048 sets of uint32 type count values ​​corresponding to 2048 channel addresses (1-2048), and each data is accurate to one decimal place.

Claims

1. An explosion-proof radioactive gas radiation detector, comprising a crystal housing and a crystal packaging shell, characterized in that: The crystal shell and the crystal packaging shell are connected by a flame-retardant sealing ring. A sodium iodide crystal is arranged in the crystal shell. One end of the sodium iodide crystal is in contact with the crystal shell, and the other end is arranged with a photomultiplier tube. The photomultiplier tube is arranged in a photomultiplier tube cover. One end face of the photomultiplier tube is provided with a photomultiplier tube pressing sheet. The photomultiplier tube pressing sheet is connected to a PCB support plate. A plurality of mutually spaced circuit boards are arranged on the PCB support plate, and the circuit boards are connected by copper columns.

2. The explosion-proof radioactive gas radiation detector according to claim 1, characterized in that: The rear end of the sodium iodide crystal is connected to the photomultiplier tube through a light guide.

3. The explosion-proof radioactive gas radiation detector according to claim 1, characterized in that: Photomultiplier tube pressure rings are also arranged on both sides of the photomultiplier tube.

4. The explosion-proof radioactive gas radiation detector according to claim 1, characterized in that: The crystal housing is made of stainless steel.

5. The explosion-proof radioactive gas radiation detector according to claim 1, characterized in that: The circuit board includes a voltage divider circuit board, a preamplifier board, a multi-channel, and a communication board.

6. The explosion-proof radioactive gas radiation detector according to claim 5, characterized in that: The voltage-dividing circuit board, the preamplifier board, the multi-channel and the communication board are connected in sequence from left to right through lines.

7. The explosion-proof radioactive gas radiation detector according to claim 6, characterized in that: The intervals between the voltage divider circuit board, the preamplifier board, the multichannel board and the communication board are greater than 15 mm.

8. The explosion-proof radioactive gas radiation detector according to claim 5, characterized in that: A blue LED lamp is also arranged between the communication board and the voltage-dividing circuit board.

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