Current source module and nuclear radiation monitoring device capable of simulating ionization chamber output current

Abstract

The application discloses a current source module capable of simulating output current of an ionization chamber and a nuclear radiation monitoring device, and the current source module comprises an interface unit, a program-controlled switch unit, a V-I conversion unit, a 2N-way DAC, a control unit and a power supply unit which are sequentially connected. The 2N-way DAC outputs multiple voltage signals, then the voltage signals are converted into current signals by the V-I conversion unit, the current signals can enter a preprocessor after the program-controlled switch and the interface, and the control unit can control the size of the voltage signal output by each channel of the DAC and the closing of the program-controlled switch, so that the size of the output current and the control of the direct current or pulse current are realized. The application can simulate the current generated by the ionization chamber in a gamma radiation field, and realizes the detection and result evaluation of the nuclear radiation monitoring device which is composed of the ionization chamber and the preprocessor and cannot be disassembled.

Description

Technical Field

[0001] This invention relates to the field of nuclear radiation monitoring technology, and in particular to a current source module and a nuclear radiation monitoring device that can simulate the output current of an ionization chamber. Background Technology

[0002] With increasing emphasis on nuclear safety, the monitoring of radioactive materials under extreme environmental conditions is receiving more and more attention. By installing nuclear radiation monitoring devices that can still function normally under harsh environments in places such as nuclear power plants and spent fuel reprocessing facilities, the radioactivity levels in the surrounding environment can be monitored so as to assess the safety of nuclear facilities and the stability of processes.

[0003] An ionization chamber is a detector that measures ionizing radiation by utilizing the ionization effect. It is widely used in nuclear physics, biomedicine, and environmental monitoring. An ionization chamber typically consists of a sealed outer electrode and a central electrode, with a medium gas such as argon filling the space between the two electrodes. When the ionization chamber is operating, a high voltage is applied to the central electrode, generating a strong electric field. When radiating particles pass through the gas, they collide with gas molecules, causing some molecules to be ionized—that is, losing or gaining an electron. These free electrons and ions move towards the anode and cathode under the influence of the electric field. Inside the ionization chamber, electrons accelerate along the electric field lines, colliding with gas molecules again, generating more ionization events. Under the influence of the electric field, positive and negative ions drift towards the negative and positive electrodes, respectively, forming an ionization current. Since the ionization current is proportional to the intensity of the radiation, measuring this current yields the intensity of the ionizing radiation.

[0004] Nuclear radiation monitoring devices that use ionization chambers to measure nuclear radiation typically consist of an ionization chamber and a preprocessor connected to the input end of the ionization chamber. Due to the harsh working environment, the ionization chamber does not contain electronic circuits for measurement. The output current signal of the ionization chamber needs to be processed by the preprocessor to obtain the intensity of ionizing radiation.

[0005] In practical applications, to ensure the effectiveness of nuclear radiation monitoring devices, regular testing is generally required. Two common methods exist: one is to disassemble the main components, such as the detector and preprocessor, and place them in a standard dose field for testing; the other is to place a radiation source near the detector and observe the device's response. However, for nuclear radiation monitoring devices installed in special areas or those that cannot be disassembled, it is neither feasible to disassemble the device nor convenient to place a radiation source, making the above methods unsuitable for effective testing. Summary of the Invention

[0006] Therefore, it is necessary to provide a current source module and a nuclear radiation monitoring device that can simulate the output current of an ionization chamber in order to address the above-mentioned technical problems. This module can simulate the current generated when the ionization chamber is in a gamma radiation field, and enable the detection and result evaluation of a non-detachable nuclear radiation monitoring device consisting of an ionization chamber and a pre-processor.

[0007] In a first aspect, the present invention provides a current source module capable of simulating the output current of an ionization chamber, comprising:

[0008] An interface unit for electrical connection to the input terminal of a preprocessor;

[0009] The programmable switch unit has its output terminal electrically connected to the input terminal of the interface unit.

[0010] The VI conversion unit is used to convert voltage signals into current signals. The output of the VI conversion unit is electrically connected to the input of the programmable switch unit.

[0011] A 2N-channel DAC is used to convert input digital voltage signals into 2N analog voltage signals. The output of the 2N-channel DAC is electrically connected to the input of the VI conversion unit, where N is a positive integer.

[0012] A control unit is used to control the closing of the programmable switches in the programmable switch unit and to control the magnitude of the output voltage signal of each of the 2N DACs. The output terminal of the control unit is electrically connected to both the programmable switch unit and the 2N DACs.

[0013] The power supply unit is used to supply power to the current source module. The input of the power supply unit is connected to an external power supply, and the output of the power supply unit is electrically connected to the programmable switch unit, the 2N-channel DAC, the VI conversion unit, and the control unit.

[0014] The programmable switch unit, VI conversion unit, 2N-channel DAC, control unit, and power supply unit are all grounded.

[0015] In one embodiment, the power supply unit includes a 12V input terminal, a 3.3V output terminal, and a 12V output terminal;

[0016] The 12V input terminal is connected to an external 12V voltage, the 3.3V output terminal is electrically connected to the control unit and the 2N-channel DAC, and the 12V output terminal is electrically connected to the programmable switch unit and the VI conversion unit.

[0017] In one embodiment, the 2N-channel DAC includes N sets of conversion circuits, each set of conversion circuits including a low-range conversion circuit and a high-range conversion circuit;

[0018] The VI conversion unit includes 2N VI conversion sub-units, the programmable switch unit includes 2N programmable switches, and the interface unit includes 2N interfaces.

[0019] Along the signal input and output directions, each low-range conversion circuit and high-range conversion circuit has a VI conversion subunit, a programmable switch and an interface connected in series at the rear end.

[0020] In one embodiment, the control unit is further provided with an RS485 communication subunit for electrical connection with external devices. The RS485 communication subunit includes a 485A interface for transmitting data and a 485B interface for receiving data.

[0021] Both the 485A and 485B interfaces are electrically connected to external devices.

[0022] Secondly, the present invention also provides a nuclear radiation monitoring device, including the aforementioned current source module capable of simulating the output current of an ionization chamber, N ionization chambers, and N preprocessors;

[0023] The output of each ionization chamber is electrically connected to a preprocessor. The interface of each set of conversion circuits connected in series is electrically connected to the input of a preprocessor.

[0024] The preprocessor is equipped with a low-range signal input terminal and a high-range signal input terminal. The interface connected in series with the low-range conversion circuit is electrically connected to the low-range signal input terminal, and the interface connected in series with the high-range conversion circuit is electrically connected to the high-range signal input terminal.

[0025] In one embodiment, the output terminal of the ionization chamber includes a low-range signal output terminal and a high-range signal output terminal. The low-range signal output terminal is electrically connected to the low-range signal input terminal of the pre-processor, and the high-range signal output terminal is electrically connected to the high-range signal input terminal of the pre-processor.

[0026] The beneficial effects of this invention are as follows: The current source module of this invention, which can simulate the output current of an ionization chamber, outputs multiple voltage signals through a 2N-channel DAC. These voltage signals are then converted into current signals by a VI conversion unit. The current signals, after passing through a programmable switch and interface, can enter the pre-processor. Furthermore, the control unit can control the magnitude of each output voltage signal from the DAC and the closing of the programmable switch, thereby controlling the magnitude of the output current and whether it is a DC or pulsed current. This invention can simulate the current generated when the ionization chamber is in a gamma radiation field and use this simulation to replace the current generated by the ionization chamber in the pre-processor, enabling the detection and result evaluation of a non-detachable nuclear radiation monitoring device composed of an ionization chamber and a pre-processor. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a current source module that can simulate the output current of an ionization chamber, provided in an embodiment of the present invention.

[0028] Figure 2 A schematic diagram of the current source module that can simulate the output current of the ionization chamber when N is 4;

[0029] Figure 3 A schematic diagram of the nuclear radiation monitoring device provided in this embodiment of the invention when N is 1. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] In one embodiment, such as Figure 1 As shown, this embodiment includes a current source module that can simulate the output current of an ionization chamber. The current source module includes...

[0032] An interface unit for electrical connection to the input terminal of a preprocessor;

[0033] The programmable switch unit has its output terminal electrically connected to the input terminal of the interface unit.

[0034] The VI conversion unit is used to convert voltage signals into current signals. The output of the VI conversion unit is electrically connected to the input of the programmable switch unit.

[0035] A 2N-channel DAC is used to convert input digital voltage signals into 2N analog voltage signals. The output of the 2N-channel DAC is electrically connected to the input of the VI conversion unit, where N is a positive integer.

[0036] A control unit is used to control the closing of the programmable switches in the programmable switch unit and to control the magnitude of the output voltage signal of each of the 2N DACs. The output terminal of the control unit is electrically connected to both the programmable switch unit and the 2N DACs.

[0037] The power supply unit is used to supply power to the current source module. The input of the power supply unit is connected to an external power supply, and the output of the power supply unit is electrically connected to the programmable switch unit, the 2N-channel DAC, the VI conversion unit, and the control unit.

[0038] The programmable switch unit, VI conversion unit, 2N-channel DAC, control unit, and power supply unit are all grounded.

[0039] Specifically, the power supply unit conditions the external power supply voltage and supplies power to the programmable switch unit, the 2N-channel DAC, the VI conversion unit, and the control unit. The control unit can control the magnitude of the 2N voltage signals converted by the 2N-channel DAC to control the magnitude of the analog current within the gamma dose rate measurement range, and the control unit can control the closing of the programmable switches within the programmable switch unit to control the output of the current source module.

[0040] It should be noted that the magnitude of the simulated current can be calculated based on the value of the dose rate to be simulated in the gamma radiation field. The specific calculation formula is: output current value = simulated dose rate × conversion coefficient, and the conversion coefficient is determined by the ionization chamber to be simulated.

[0041] The current source module in this embodiment, which can simulate the output current of an ionization chamber, can simulate and replace the current of different magnitudes output by the ionization chamber in a gamma radiation field.

[0042] In one embodiment, the power supply unit includes a 12V input terminal, a 3.3V output terminal, and a 12V output terminal; the 12V input terminal is connected to an external 12V voltage, the 3.3V output terminal is electrically connected to the control unit and the 2N-channel DAC, and the 12V output terminal is electrically connected to the programmable switch unit and the VI conversion unit.

[0043] In one embodiment, the 2N-channel DAC includes N sets of conversion circuits, each set of conversion circuits including a low-range conversion circuit and a high-range conversion circuit.

[0044] The VI conversion unit includes 2N VI conversion sub-units, the programmable switch unit includes 2N programmable switches, and the interface unit includes 2N interfaces. Along the signal input and output directions, each low-range conversion circuit and high-range conversion circuit has a VI conversion sub-unit, a programmable switch, and an interface connected in series at the rear end.

[0045] Specifically, the current output of the interface connected in series with the low-range conversion circuit is the low-range current, which is controlled within the range of 20pA to 50nA. The current output of the interface connected in series with the high-range conversion circuit is the high-range current, which is controlled within the range of 1.0nA to 2.0uA.

[0046] It should be noted that when N is greater than 1, the control unit can control the timing of the closing / opening of the programmable switches connected in series with different conversion circuits to realize the timing of the output current of the control interface of different preprocessors. This is used to simulate the order and interval of time when materials containing radioactive substances pass through the monitoring areas of different detectors.

[0047] When a programmable switch is continuously closed, the current output from the interface connected to that programmable switch is DC, used to simulate the output of the ionization chamber under constant dose rate irradiation; when a programmable switch is opened, the current output from the interface connected to that programmable switch is turned off; when a programmable switch is closed and opened at a specified frequency, the current output from the interface connected to that programmable switch is pulse current.

[0048] In addition, when the output current is a pulse current, the control unit can also control the current pulse width by controlling the closing time and opening time interval of the programmable switch, which can simulate the passage time of materials containing radioactive substances through the ionization chamber area.

[0049] In one embodiment, the control unit is further provided with an RS485 communication subunit for electrical connection with an external device. The RS485 communication subunit includes a 485A interface for transmitting data and a 485B interface for receiving data; both the 485A and 485B interfaces are electrically connected to the external device.

[0050] Specifically, external devices can be connected to the control power supply via wired or wireless means to achieve data interaction with the control unit. External devices can be, but are not limited to, computers.

[0051] In a specific embodiment, such as Figure 2 As shown, in this embodiment, N is 4. The 8-channel DAC can convert the DAC input voltage into a voltage signal. There are four groups of conversion circuits, with two channels forming a group. Each group of conversion circuits outputs a voltage signal consisting of a high-range voltage signal and a low-range voltage signal. The final current signal output by the interface unit also includes a high-range current signal and a low-range current signal. One of the two interfaces connected in series in each group of conversion circuits is the high-range current interface, and the other is the low-range current interface. Both interfaces connected in series in each group of conversion circuits can be connected to a pre-processor simultaneously.

[0052] Ultimately, a total of 8 current signals, from I1 to I8, are generated, forming four groups of current signals: I1-I2, I3-I4, I5-I6, and I7-I8. Among them, I1, I3, I5, and I7 are low-range current signals, while I2, I4, I6, and I8 are high-range current signals.

[0053] The current source module that can simulate the output current of an ionization chamber in this embodiment can simultaneously simulate the output current of multiple ionization chambers. That is, the current source module that can simulate the output current of an ionization chamber in this embodiment can simultaneously provide detection and calibration for nuclear radiation monitoring devices with multiple different ionization chambers.

[0054] Secondly, the present invention also provides a nuclear radiation monitoring device, including a current source module capable of simulating the output current of an ionization chamber in any of the above embodiments, N ionization chambers, and N preprocessors;

[0055] The output of each ionization chamber is electrically connected to a preprocessor. The interface of each set of conversion circuits connected in series is electrically connected to the input of a preprocessor.

[0056] The preprocessor is equipped with a low-range signal input terminal and a high-range signal input terminal. The interface connected in series with the low-range conversion circuit is electrically connected to the low-range signal input terminal, and the interface connected in series with the high-range conversion circuit is electrically connected to the high-range signal input terminal.

[0057] Specifically, the current source module that can simulate the output current of the ionization chamber has multiple output currents, which can simultaneously detect multiple non-removable nuclear radiation monitoring devices consisting of ionization chambers and pre-processors.

[0058] In one embodiment, the output terminal of the ionization chamber includes a low-range signal output terminal and a high-range signal output terminal. The low-range signal output terminal is electrically connected to the low-range signal input terminal of the pre-processor, and the high-range signal output terminal is electrically connected to the high-range signal input terminal of the pre-processor. The ionization chamber programmable switch is electrically connected to the control unit.

[0059] For example, when N is 1, the connection relationship between the current source module, the ionization chamber, and the preprocessor is as follows: Figure 3 As shown. During normal operation of the ionization chamber, the control unit controls the programmable switches in all programmable switch units to disconnect. When it is necessary to inspect the non-removable nuclear radiation monitoring device consisting of the ionization chamber and the preprocessor, the high voltage of the ionization chamber is shut off. The control unit then controls the programmable switches in the programmable switch units to remain open or close and open at a specified frequency, thus achieving simulated current source output. Shutting off the high voltage of the ionization chamber can be achieved by setting a switch controlled by the control unit.

[0060] It should be noted that after the high voltage of the ionization chamber is turned off, the ionization chamber will basically not output current or the magnitude of the current generated by the ionization chamber is much smaller than the magnitude of the current generated by the current source in this embodiment. Therefore, when using the current source in this embodiment to generate simulated current to detect nuclear radiation, it is not necessary to cut off the current generated by the ionization chamber and transmitted to the preprocessor.

[0061] The nuclear radiation monitoring device of this embodiment can detect and evaluate the results of a non-removable nuclear radiation monitoring device consisting of an ionization chamber and a preprocessor without disassembling the device to prevent it from being exposed to a gamma radiation field.

[0062] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A current source module for simulating the output current of an ionization chamber, characterized by, The application relates to a current source module for connecting to the output interface of a pre-processor, comprising: an interface unit electrically connected to the input end of the pre-processor; a program-controlled switch unit, the output end of which is electrically connected to the input end of the interface unit; a V-I conversion unit for converting a voltage signal into a current signal, the output end of which is electrically connected to the input end of the program-controlled switch unit; a 2N-way DAC for converting an input digital voltage signal into a 2N-way analog voltage signal, the output end of which is electrically connected to the input end of the V-I conversion unit, N being a positive integer; a control unit for controlling the closing of the program-controlled switch in the program-controlled switch unit and the size of the output voltage signal of each way of the 2N-way DAC, the output end of the control unit being electrically connected to the program-controlled switch unit and the 2N-way DAC; a power supply unit for supplying power to the current source module, the input end of the power supply unit being connected to an external power supply, and the output end of the power supply unit being electrically connected to the program-controlled switch unit, the 2N-way DAC, the V-I conversion unit and the control unit; the program-controlled switch unit, the V-I conversion unit, the 2N-way DAC, the control unit and the power supply unit are all grounded; when N is greater than 1, the control unit can realize the time for connecting the control interface output current of different pre-processors by controlling the execution time of the closing / opening action of the program-controlled switch of different groups of conversion circuits in series, so as to simulate the time sequence and interval length of the materials containing radioactive substances passing through the monitoring area of different detectors; when a certain program-controlled switch is continuously closed, the current output by the interface connected to the program-controlled switch is direct current, which is used for simulating the output of an ionization chamber under constant dose rate irradiation; when a certain program-controlled switch is opened, the current output by the interface connected to the program-controlled switch is turned off; when a certain program-controlled switch is closed and opened at a specified frequency, the current output by the interface connected to the program-controlled switch is pulse current.

2. The current source module capable of simulating the output current of an ionization chamber according to claim 1, characterized in that, the power supply unit comprises a 12V input end, a 3.3V output end and a 12V output end; the 12V input end is connected to an external 12V voltage, the 3.3V output end is electrically connected to the control unit and the 2N-way DAC, and the 12V output end is electrically connected to the program-controlled switch unit and the V-I conversion unit.

3. The current source module capable of simulating the output current of an ionization chamber according to claim 2, characterized in that, the 2N-way DAC comprises N groups of conversion circuits, each group of conversion circuits comprising a low-range conversion circuit and a high-range conversion circuit; the V-I conversion unit comprises 2N V-I conversion sub-units, the program-controlled switch unit comprises 2N program-controlled switches, and the interface unit comprises 2N interfaces; in the direction of signal input and output, a V-I conversion sub-unit, a program-controlled switch and an interface are sequentially connected in series at the back end of each low-range conversion circuit and high-range conversion circuit.

4. The current source module capable of simulating the output current of an ionization chamber according to claim 3, characterized in that, the control unit is further provided with an RS485 communication sub-unit for electrically connecting to an external device, the RS485 communication sub-unit comprising a 485A interface for transmitting data and a 485B interface for receiving data; the 485A interface and the 485B interface are both electrically connected to the external device.

5. A nuclear radiation monitoring device, characterised in that, The current source module capable of simulating ionization chamber output current, N ionization chambers and N pre-processors according to any one of claims 1 to 4; The output end of each ionization chamber is electrically connected with a pre-processor, and the interface of each group of conversion circuit of the current source module capable of simulating ionization chamber output current is electrically connected with the input end of a pre-processor; The pre-processor is provided with a low-range signal input end and a high-range signal input end, the interface of the low-range conversion circuit is electrically connected with the low-range signal input end, and the interface of the high-range conversion circuit is electrically connected with the high-range signal input end.

6. The nuclear radiation monitoring device of claim 5, wherein, The output end of the ionization chamber comprises a low-range signal output end and a high-range signal output end, the low-range signal output end is electrically connected with the low-range signal input end of the pre-processor, and the high-range signal output end is electrically connected with the high-range signal input end of the pre-processor.

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