Measuring-range-adjustable low-level liquid activity monitoring equipment and measuring-range-adjustable low-level liquid activity monitoring method

Abstract

The invention discloses a low-level liquid activity monitoring device and method with an adjustable measurement range, and belongs to the field of nuclear radiation detection.The low-level liquid activity monitoring device comprises a sampling water inlet pipe, a monitoring assembly and a sampling water outlet pipe, the monitoring assembly comprises a lead shielding part, the lead shielding part is provided with a shielding cavity, and a scintillator detector and a sampler are arranged in the shielding cavity; the sampler is a U-shaped piece, the U-shaped piece comprises a U-shaped sampling cavity and a U-shaped groove, the sampling water inlet pipe and the sampling water outlet pipe are both communicated with the U-shaped sampling cavity, and the detection end of the scintillator detector extends into the U-shaped groove; and a shielding material layer is arranged between the detection end of the scintillator detector and the inner wall of the U-shaped groove, so that the detection performance of the monitoring equipment can be improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nuclear radiation detection, and particularly relates to a low-level liquid activity monitoring device and method with adjustable measurement range. BACKGROUND

[0002] The low-level liquid activity monitor is a device specially used for detecting the gamma ray activity concentration in low-level radioactive liquid, and its core function is to monitor the radioactive activity concentration in the sampled water through an offline sampling mode. Since the low-level liquid activity monitor is applied in different areas of the nuclear power plant, different monitors perform the same monitoring function, but their measurement ranges are different. Therefore, for different monitoring areas, the low-level liquid activity monitor with the corresponding measurement range needs to be used.

[0003] The common low-level liquid activity monitoring device currently includes a scintillator detector, which can detect the radioactive activity concentration in the sampled water. However, the detection performance of the existing monitoring device is poor, and the measurement range is limited. SUMMARY

[0004] In order to solve the above problems in the prior art, the present application provides a low-level liquid activity monitoring device and method with adjustable measurement range. The technical problem to be solved by the present application is solved by the following technical scheme: In a first aspect, the present application provides a low-level liquid activity monitoring device with adjustable measurement range, which comprises a sampling inlet pipe, a monitoring assembly and a sampling outlet pipe. The monitoring assembly comprises a lead shielding member, and the lead shielding member has a shielding cavity. A scintillator detector and a sampler are arranged in the shielding cavity. The sampler is a U-shaped piece, which comprises a U-shaped sampling cavity and a U-shaped groove. The sampling inlet pipe and the sampling outlet pipe are both in communication with the U-shaped sampling cavity, and the detection end of the scintillator detector extends into the U-shaped groove. A shielding material layer is arranged between the detection end of the scintillator detector and the inner wall of the U-shaped groove.

[0005] In an embodiment of the present application, a first main switch, a filtering device, a water pump, an adjusting valve and a first auxiliary switch are sequentially arranged on the sampling inlet pipe. A flow meter and a second main switch are sequentially arranged on the sampling outlet pipe.

[0006] In an embodiment of the present application, a liquid inlet pipe and a liquid outlet pipe are further included. The liquid inlet pipe is connected to the sampling inlet pipe, and the liquid inlet pipe is located between the first auxiliary switch and the lead shielding member. The liquid outlet pipe is connected to the sampling outlet pipe, and the liquid outlet pipe is located between the flow meter and the second main switch.

[0007] In one embodiment of the present application, a gas flushing inlet pipe and a gas flushing outlet pipe are further included, the gas flushing outlet pipe is connected to the sampling inlet water pipe and located between the first auxiliary switch and the lead shielding, and the gas flushing inlet pipe is connected to the sampling outlet water pipe and located between the flow meter and the second main switch.

[0008] In one embodiment of the present application, a flushing water pipe is further included, the flushing water pipe is connected to the sampling inlet water pipe and located between the first main switch and the filtering device.

[0009] In one embodiment of the present application, a secondary pipe is further included, a second auxiliary switch is further arranged between the filtering device and the water pump, and two ends of the secondary pipe are connected to the sampling inlet water pipe, one end of the sampling inlet water pipe is located between the filtering device and the water pump, and the other end of the sampling inlet water pipe is located between the water pump and the regulating valve.

[0010] In one embodiment of the present application, the scintillation detector is a NaI (Tl) scintillation detector.

[0011] In one embodiment of the present application, an in-situ radiation processor, an electrical wiring box, an electrical control box and an audible and visual alarm are further included.

[0012] In a second aspect, the present application further provides a method for monitoring low-level liquid activity with adjustable measuring range, which is applied to the low-level liquid activity monitoring device with adjustable measuring range provided in the above-mentioned solution, and the low-level liquid activity monitoring device includes a sampling inlet water pipe, a monitoring assembly and a sampling outlet water pipe, the monitoring assembly includes a lead shielding, the lead shielding has a shielding cavity, and the shielding cavity is provided with a scintillation detector and a sampler, and the method includes the following steps: Step one: determining the size of the lead shielding; Step two: determining the structure and volume of the sampler, and setting the sampler as a U-shaped structure; Step three: determining the size of the scintillation detector; Step four: determining the lowest detectable lower limit of the scintillation detector; Step five: setting a shielding material layer between the scintillation detector and the sampler, gradually increasing the thickness of the shielding material layer, calculating a first relationship curve between the thickness of the shielding material layer and the sensitivity of the scintillation detector, calculating a first correction coefficient based on the first relationship curve, and determining the thickness of the shielding material layer based on the first correction coefficient; Step six: adjusting the size of the sampler, calculating a second relationship curve between the size of the sampler and the sensitivity of the scintillation detector, calculating a second correction coefficient based on the second relationship curve, and determining the size of the sampler based on the second correction coefficient.

[0013] In one embodiment of the present application, the thickness of the lead shielding is 9.5cm~10.5cm.

[0014] Compared with the prior art, the present application has the following beneficial effects: In the above-mentioned scheme of the present application, the low-level liquid activity monitoring device comprises a sampling inlet water pipe, a monitoring assembly and a sampling outlet water pipe. The monitoring assembly comprises a lead shielding member, the lead shielding member has a shielding cavity, and a scintillator detector and a sampler are arranged in the shielding cavity. The sampler is a U-shaped member, which comprises a U-shaped sampling cavity and a U-shaped groove. The sampling inlet water pipe and the sampling outlet water pipe are both in communication with the U-shaped sampling cavity, and the detection end of the scintillator detector extends into the U-shaped groove. A shielding material layer is arranged between the detection end of the scintillator detector and the inner wall of the U-shaped groove. With this structure, the sampling water can enter the U-shaped sampling cavity of the sampler through the sampling inlet water pipe, and the scintillator detector can detect the low-level radioactive sampling water in the U-shaped sampling cavity, so as to obtain the radioactivity concentration in the sampling water. The scintillator detector and the sampler in the present application are both located in the shielding cavity, and are shielded by the shielding cavity, which can reduce the influence of external gamma ray radioactivity and reduce the background count rate in the detector, thereby improving the detection performance of the monitoring device on low-level radioactive liquid. At the same time, the shielding material layer of the present application can shield between the scintillator detector and the U-shaped sampling cavity to change the detection efficiency of the scintillator detector. By adjusting the thickness of the shielding material layer, the detection efficiency of the scintillator detector can be adjusted, and then the measurement range of the scintillator detector on the radioactivity concentration of the radioactive liquid can be adjusted.

[0015] The present application will be further described in detail below with reference to the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic diagram of a low-level liquid activity monitoring device in an embodiment of the present application; Figure 2 is a schematic diagram of a monitoring assembly in an embodiment of the present application; Figure 3 is a schematic diagram of a low-level liquid activity monitoring method in an embodiment of the present application; Figure 4 is a schematic diagram of the step of adjusting the measurement range in an embodiment of the present application.

[0017] The drawings show that: 1 is a sampling inlet water pipe, 11 is a first main switch, 12 is a filtering device, 13 is a water pump, 14 is an adjusting valve, 15 is a first auxiliary switch, 2 is a monitoring assembly, 21 is a lead shielding member, 22 is a scintillator detector, 23 is a sampler, 3 is a sampling outlet water pipe, 31 is a flow meter, 32 is a second main switch, 4 is a shielding material layer, 5 is a liquid flush inlet pipe, 6 is a liquid flush outlet pipe, 7 is a gas flush inlet pipe, 8 is a gas flush outlet pipe, 9 is a flushing water pipe, and 10 is a secondary pipe. DETAILED DESCRIPTION

[0018] The application will be described in further detail below with reference to specific embodiments, but the embodiments of the application are not limited thereto.

[0019] Embodiment one: At present, for the monitoring of the radioactivity concentration of the low-level radioactive water monitoring channel of the nuclear power plant, the monitoring equipment usually uses a scintillator detector for energy spectrum measurement, and the maximum count rate of the detector is 200 kcps (maximum count value per unit time). The measurement range of the radioactivity concentration of the low-level radioactive water monitoring channel can reach six orders of magnitude. Generally, the technical index of the low-level radioactive water monitoring channel of the nuclear power plant also requires six orders of magnitude. However, due to the different requirements of different types of units (for example, AP1000 reactor type, CAP1000 reactor type, China General Nuclear Hualong No. 1 reactor type, and Guangdong Nuclear Hualong No. 1 reactor type), the measurement range intervals of the low-level radioactive water monitoring channels with the same function are also different from each other. Considering the requirements of all reactor types, the measurement range of the monitoring channel is required to be between 9-10 orders of magnitude. Therefore, the existing low-level radioactive water measurement device cannot directly meet the 9-10 order of magnitude measurement condition. At present, the solution adopted in the market is to design monitoring equipment with corresponding measurement range according to different reactor types. This leads to an increase in the number of equipment types, resulting in an increase in research and development costs and production costs.

[0020] Based on the above problems, please refer to Figure 1 and Figure 2 The embodiment of the application provides a low-level liquid activity monitoring device with adjustable measurement range, which comprises a sampling inlet pipe 1, a monitoring assembly 2 and a sampling outlet pipe 3. The monitoring assembly 2 comprises a lead shielding member 21, the lead shielding member 21 has a shielding cavity, and a scintillator detector 22 and a sampler 23 are arranged in the shielding cavity. The sampler 23 is a U-shaped member, which comprises a U-shaped sampling cavity and a U-shaped groove. The sampling inlet pipe 1 and the sampling outlet pipe 3 are in communication with the U-shaped sampling cavity, and the detection end of the scintillator detector 22 extends into the U-shaped groove. A shielding material layer 4 is arranged between the detection end of the scintillator detector 22 and the inner wall of the U-shaped groove.

[0021] In the above scheme, the low-level liquid activity monitoring device comprises a sampling inlet pipe 1, a monitoring assembly 2, and a sampling outlet pipe 3. The monitoring assembly 2 comprises a lead shielding 21 having a shielding cavity, and a scintillator detector 22 and a sampler 23 are arranged in the shielding cavity. The sampler 23 is a U-shaped piece comprising a U-shaped sampling cavity and a U-shaped groove. The sampling inlet pipe 1 and the sampling outlet pipe 3 are both in communication with the U-shaped sampling cavity, and the detection end of the scintillator detector 22 extends into the U-shaped groove. A shielding material layer 4 is arranged between the detection end of the scintillator detector 22 and the inner wall of the U-shaped groove. With this structure, the sampling water can enter the U-shaped sampling cavity of the sampler 23 through the sampling inlet pipe 1, and the scintillator detector 22 can detect the low-level radioactive sampling water in the U-shaped sampling cavity, so as to obtain the radioactivity concentration in the sampling water. The scintillator detector 22 and the sampler 23 in the present application are both located in the shielding cavity, and are shielded by the shielding cavity, which can reduce the influence of external gamma ray radiation and reduce the background count rate in the detector, thereby improving the detection performance of the monitoring device on low-level radioactive liquid. Meanwhile, the shielding material layer 4 in the present application can shield between the scintillator detector 22 and the U-shaped sampling cavity to change the detection efficiency of the scintillator detector 22. By adjusting the thickness of the shielding material layer 4, the detection efficiency of the scintillator detector 22 can be adjusted, and then the measurement range of the scintillator detector 22 on the radioactivity concentration of the radioactive liquid can be adjusted.

[0022] It can be understood that the present application realizes the requirements of different types of units on the activity concentration measurement range of the low-level water monitoring channel through a set of low-level water measurement equipment. The measurement range of the low-level water activity concentration can reach 12 orders of magnitude (according to the requirements of different types of monitoring channels and the requirements of corresponding monitoring channel technical indicators, any 6 orders of magnitude within the range of 12 orders of magnitude are selected to match), which can completely envelope the difference of the measurement range of different types of units, and realize that one set of equipment can meet the requirements of different types of units on the radioactivity concentration measurement range.

[0023] In some embodiments of the present application, the scintillator detector 22 is a NaI(Tl) scintillator detector. The NaI(Tl) scintillator detector is an energy converter for detecting gamma rays and X-rays. It can convert nuclear radiation invisible to the human eye into weak light signals that can be recognized, analyzed and recorded by electronic devices, and ultimately calculate the intensity and energy of the radiation. At the same time, the NaI(Tl) scintillator detector has the advantages of low own background, high energy resolution, meeting the basic requirements of measurement and nuclide identification, low price, and wide application range.

[0024] In some embodiments of the present application, the NaI (Tl) scintillator detector in the present application is a large-size NaI (Tl) scintillator detector. The large-size NaI (Tl) detector can improve the detection capability of the device, so that a lower lower limit of measurement can be achieved under the same conditions.

[0025] In some embodiments of the present application, the lead shielding 21 can reduce the influence of external gamma ray radioactivity, reduce the background count rate in the detector, improve the detection capability of the detector for low radioactivity liquid, and at the same time can reduce the volume and weight of the device, increase the compactness of the device arrangement.

[0026] In some embodiments of the present application, the sampler 23 is arranged in a U-shaped structure, and the sampling cavity is a U-shaped cavity, which can increase the contact area with the detector, shorten the time required for the monitor to reach the detection lower limit, and improve the detection efficiency of the detector per unit time.

[0027] In some embodiments of the present application, the material of the shielding material layer 4 can be lead, tin, copper, aluminum and the like.

[0028] In some embodiments of the present application, the radioactive sewage in the pipeline is introduced into the U-shaped sampling cavity through the sampling inlet pipe 1, and the scintillator detector 22 detects the gamma photon radiation signal in the radioactive sewage.

[0029] In some embodiments of the present application, the U-shaped piece includes a left tube, a lower arc tube and a right tube connected in sequence, the upper part of the left tube is provided with a water outlet, the upper part of the right tube is provided with a water inlet, and the sampling inlet pipe 1 and the sampling outlet pipe 3 are in communication with the water inlet and the water outlet respectively.

[0030] In some embodiments of the present application, the low radioactivity liquid activity monitor is used to measure the activity concentration level (unit: Bq / m 3 ) of the radioactive liquid, and the radioactive information is converted into a current signal by the detector, a pulse signal is generated through current-voltage conversion (I / V conversion), and then the measurement of the radioactive liquid radiation information is realized through counting. The measurement of the activity concentration of the radioactive liquid is realized through the conversion relationship between the counting rate of the detector and the activity of the radioactive liquid, and the conversion relationship satisfies the following formula:

[0031] Wherein, represents the activity concentration level of the radioactive liquid, and the unit is Bq / m 3 . represents the counting rate of the detector, and the unit is cps. For the NaI (Tl) detector, the maximum counting rate can reach about 200kcps. The conversion coefficient of the detector count rate and the activity concentration of radioactive liquid, usually also called sensitivity, with the unit of cps / Bq / m 3 .

[0032] From the above formula, under the condition of constant , since the maximum count rate of the current NaI(Tl) detector can only reach about 200kcps, in order to ensure the accuracy of the measurement results, the lower limit of the count rate of the detector is taken to be 0.1cps. The measurable range of the activity concentration of the radioactive liquid obtained by conversion can only measure 6 orders of magnitude.

[0033] In order to envelope the difference of the activity concentration measurement range of the monitoring channel of the radioactive liquid of different reactor types, from the perspective of calculation principle, by changing the sensitivity , the adjustment of the activity concentration measurement range of the radioactive liquid can be realized.

[0034] The main factors affecting the sensitivity are the volume of the sampler 23 and the detection efficiency of the detector. By changing these two parameters, the sensitivity can be changed.

[0035] There are two main methods to change the detection efficiency of the detector. One is to change the size of the detector crystal to change the detection efficiency of the detector, but this method is very difficult. After the detector is packaged, the internal structure of the detector is fixed and cannot be changed. Forced change can easily affect the overall performance of the detector and cause damage to the detector. Replacing the entire detector is too expensive and not easy to adopt. The second method is to add shielding material to the surface of the shell at the position of the detection crystal of the detector. With the increase of the thickness of the shielding material, the detection efficiency of the detector gradually decreases. This method only needs to reserve a space for adding shielding between the detector and the sampler 23. By adjusting the thickness of the shielding material, the detection efficiency of the detector can be changed, the sensitivity can be changed, and finally the adjustment of the activity concentration measurement range of the radioactive liquid can be realized.

[0036] The second way to change the sensitivity is to change the volume of the sampler 23. By changing the size of the volume of the sampler 23, the sensitivity can be changed, and finally the adjustment of the activity concentration measurement range of the radioactive liquid can be realized.

[0037] The monitoring device of the whole low-level liquid activity monitor mainly consists of a lead shielding 21, a sampler 23 and a detector, wherein the detector and the sampler 23 are installed in the shielding cavity of the lead shielding 21. Once the structure of the lead shielding 21 is fixed, it is not easy to change, and the space inside it is limited. Therefore, the adjustment method for the measurement range of the radioactivity liquid activity concentration has certain sequence requirements.

[0038] Firstly, a large-size NaI(Tl) detector is selected to ensure that the device can achieve a lower detection limit under the same conditions, and ensure that the measurement lower limit can meet the technical index requirements of all nuclear power plant types; secondly, different thicknesses of shielding materials are added in the space reserved between the detector and the sampler 23, which gradually reduces the count value of the detector for measuring the same activity concentration value, so that the measurement range of the device shifts from the low radioactivity activity concentration interval to the high radioactivity activity concentration interval; thirdly, since the monitoring assembly 2 mainly consists of a lead shielding 21, a sampler 23 and a detector, wherein the detector and the sampler 23 are installed in the lead shielding 21, the internal space of the lead shielding 21 is limited, when the second step improves the condition to the limit value, the size of the sampler 23 is replaced, and the size of the sampler 23 is replaced in the order from large to small, so as to realize the continuous migration of the measurement range of the device to the high radioactivity activity concentration interval on the basis of the second step condition. Finally, through these two ways, the original measurable range can be increased from 6 orders of magnitude to 12 orders of magnitude (in the range of 12 orders of magnitude, 6 orders of magnitude are selected to match the measurement range parameters of different types of reactors).

[0039] In some embodiments of the present application, as Figure 1As shown, the sampling inlet pipe 1 is sequentially provided with a first main switch 11, a filtering device 12, a water pump 13, an adjusting valve 14 and a first auxiliary switch 15, and the sampling outlet pipe 3 is sequentially provided with a flow meter 31 and a second main switch 32. With this structure, the first main switch 11 and the second main switch 32 can reliably control the total on-off of the sampling circuit, facilitating equipment maintenance and emergency isolation. The filtering device 12 can intercept and remove solid particle impurities that may be contained in the to-be-measured liquid, avoiding the impurities from entering the subsequent pipeline and the sampling chamber, preventing the impurities from depositing or wearing the components, and ensuring the stable operation of the water pump 13 and the cleanliness of the measurement process. The water pump 13 provides stable power for liquid circulation, ensuring that the to-be-measured liquid can be sucked from the process pipeline and continuously flow through the sampling chamber to form a stable measurement flow path. The adjusting valve 14 is used to finely adjust the liquid flow in the pipeline, so that the flow is stabilized within a set range, ensuring that the probe measures under the best flow rate condition, and improving the representativeness and accuracy of the measurement data. The flow meter 31 monitors and feeds back the liquid flow rate of the circulation circuit in real time, providing a basis for the control of the adjusting valve 14, ensuring the stability of the flow, and the flow rate data can also be used for subsequent calculation and correction of activity concentration. The first auxiliary switch 15 forms an independently operable cutoff point between the adjusting valve 14 and the monitoring assembly 2, facilitating the isolation of the monitoring assembly 2, and facilitating the maintenance, replacement of shielding material or the sampler 23 without affecting other equipment in the upstream pipeline.

[0040] In some embodiments of the present application, as shown in Figure 1 As shown, the monitoring device further comprises a liquid flushing inlet pipe 5 and a liquid flushing outlet pipe 6, the liquid flushing inlet pipe 5 is connected to the sampling inlet pipe 1, and the liquid flushing inlet pipe 5 is located between the first auxiliary switch 15 and the lead shielding member 21, the liquid flushing outlet pipe 6 is connected to the sampling outlet pipe 3, and the liquid flushing outlet pipe 6 is located between the flow meter 31 and the second main switch 32. With this structure, the liquid flushing inlet pipe 5 and the liquid flushing outlet pipe 6 constitute an independent liquid flushing circuit. When it is necessary to clean the sampling chamber and the connected pipeline, the main sampling circuit can be closed, and clean flushing liquid can be introduced from the liquid flushing inlet pipe 5. The flushing liquid will flow through the sampling chamber, carry out the to-be-measured radioactive liquid remaining in the chamber or the impurities that may deposit, and be discharged to a designated waste liquid treatment channel through the liquid flushing outlet pipe 6. This way can effectively clean the measurement chamber and the adjacent pipeline without disassembling the device, prevent cross contamination between different batches of samples, avoid long-term accumulation of radioactive substances in the chamber, and help to maintain the stability of the measurement conditions of the probe and the long-term reliability of the data.

[0041] In some embodiments of the present application, as shown in Figure 1As shown, the monitoring equipment also includes an air flushing inlet pipe 7 and an air flushing outlet pipe 8. The air flushing outlet pipe 8 is connected to the sampling water inlet pipe 1 and is located between the first auxiliary switch 15 and the lead shield 21. The air flushing inlet pipe 7 is connected to the sampling water outlet pipe 3 and is located between the flow meter 31 and the second main switch 32. With this structure, the air flushing inlet pipe 7 and the air flushing outlet pipe 8 form a gas flushing circuit. After completing liquid measurement or liquid flushing, the system can be switched to gas flushing mode. Compressed air or other inert gas is introduced through the air flushing inlet pipe 7. The gas flows through the sampling chamber and its connecting pipes, which can purge and discharge residual liquid in the chamber, including water films or droplets adhering to the chamber walls and dead corners of the pipes.

[0042] In some embodiments of this application, the sampling pipeline of the low-level liquid activity monitor includes two parts: a liquid sampling circuit and a flushing circuit.

[0043] The first path is a liquid sampling loop: liquid drawn from the process flow pipeline of the user's plant enters the water inlet pipe of the low-radioactivity liquid monitor, and then the sampling water is sent into the sampling chamber by the water pump 13 (or the water is sent into the sampling chamber by the pressure difference of the monitoring channel itself); after the sampling chamber is full, the liquid passes through the flow meter 31 installed in the downstream pipeline to measure the liquid flow velocity in the pipeline, and finally the liquid is transported back to the original process flow pipeline to establish a stable liquid circulation loop, and the detector realizes real-time measurement of the radioactivity concentration in the liquid.

[0044] The second circuit is the flushing circuit: the flushing circuit has two modes, one is gas flushing mode, and the other is liquid flushing mode. These two methods are used to flush the sampling chamber, removing any deposits and ensuring the cleanliness of the sampling chamber's interior.

[0045] In some embodiments of this application, the regulating valve 14 is used to regulate the liquid flow rate in the sampling pipeline, and the first auxiliary switch 15, the second auxiliary switch, the first main switch 11 and the second main switch 32 are all shut-off valves used to cut off or open the flow of the medium in the pipeline.

[0046] In some embodiments of this application, shut-off valves are provided on the liquid flushing inlet pipe 5, the liquid flushing outlet pipe 6, the air flushing inlet pipe 7, and the air flushing outlet pipe 8 to cut off or open the flow of the pipeline medium.

[0047] In some embodiments of this application, such as Figure 1As shown, the monitoring device further comprises a flushing water pipe 9, which is connected to the sampling water inlet pipe 1 and is located between the first main switch 11 and the filtering device 12. With this structure, the flushing water pipe 9 provides a direct flushing interface for the upstream of the filtering device 12. When the filtering device 12 needs to be maintained or the pressure drop increases due to the interception of impurities, the first main switch 11 can be closed to introduce a flushing water flow from the flushing water pipe 9. The flushing water flows through the filtering device 12 in the reverse or forward direction, which can flush out the solid particles intercepted by the filtering device 12 and discharge the system through the blowdown pipe.

[0048] In some embodiments of the present application, as shown in Figure 1 As shown, the monitoring device further comprises a secondary pipe 10, and a second auxiliary switch is arranged between the filtering device 12 and the water pump 13. The two ends of the secondary pipe 10 are connected to the sampling water inlet pipe 1, and one end of the sampling water inlet pipe 1 is located between the filtering device 12 and the water pump 13, and the other end of the sampling water inlet pipe 1 is located between the water pump 13 and the regulating valve 14. With this structure, the secondary pipe 10 provides a parallel fluid passage, so that the liquid can be sent into the sampler 23 under the action of its own pressure difference without using the water pump 13 to pump water.

[0049] In some embodiments of the present application, the monitoring device further comprises an in-situ radiation processor, an electrical wiring box, an electrical control box, and an audible and visual alarm. With this structure, the in-situ radiation processor can directly receive and process the signals transmitted by the detector, complete the conversion of the count rate to the activity concentration, data storage and display in real time, reduce the interference that the signal may be subjected to during long-distance transmission, and improve the immediacy and reliability of data processing. The electrical wiring box concentrates the electrical connections inside and outside the device, so that the line arrangement is regular, and it is convenient for inspection, maintenance and troubleshooting. The electrical control box centrally manages the power supply and control logic of the water pump 13, valve and other execution components, and realizes the automatic or manual orderly operation of the sampling, flushing and other processes. When the monitored activity concentration exceeds the preset threshold, the audible and visual alarm gives an alarm through sound and light signals, reminding the on-site personnel to pay attention, and providing a condition for timely response measures.

[0050] In some embodiments of the present application, the in-situ radiation processor converts the AC 220V power supply provided externally into DC 12V power supply required for its own work through an AC / DC power supply module, and supplies power to the external detector. Through interface conversion, the received detector monitoring data is processed and displayed on the screen, and the received data is recorded and stored on the memory.

[0051] In some embodiments of the present application, the probe converts the gamma photon radiation signal emitted in the sampling liquid into an electrical signal and transmits it to the preamplifier, the preamplifier amplifies and filters the received electrical signal, and then converts the analog signal into a digital signal after processing by the multichannel analyzer, and transmits the processed digital signal to the in-situ radiation processor. The in-situ radiation processor collects, stores and processes the signal to give the radioactivity concentration data at the location of the probe to determine that the activity of the radioactive effluent stream does not exceed the discharge limit. When the measured value exceeds the alarm threshold, the device gives an audible and visual alarm.

[0052] Embodiment two: In a second aspect, referring to Figure 3 and Figure 4 The present application also provides a low-level liquid activity monitoring method with adjustable measurement range, which is applied to the low-level liquid activity monitoring device with adjustable measurement range provided in the above-mentioned scheme. The low-level liquid activity monitoring device includes a sampling inlet pipe, a monitoring assembly and a sampling outlet pipe. The monitoring assembly includes a lead shielding member having a shielding cavity, a scintillator detector and a sampler arranged in the shielding cavity. The method includes the following steps: S1: determining the size of the lead shielding member; the lead shielding member is the outermost structure of the low-level liquid activity monitoring device, mainly composed of lead material, and its function is mainly to shield the background dose rate level of the surrounding environment and reduce the environmental background level in the space inside the lead shielding member. The thickness of the lead shielding member is calculated by Geant4 Monte Carlo simulation software to calculate the optimal thickness. The simulation calculation shows that the optimal lead shielding thickness is 10 cm, which can envelope the environmental background level required by all types of stacks on the market.

[0053] S2: determining the structure and volume of the sampler and setting the sampler as a U-shaped structure; the sampler is installed inside the lead shielding member, and the space inside the lead shielding member is limited. In order to increase the volume of the sampler as much as possible in the limited space of the lead shielding member, the shape of the sampler is designed as a U-shaped structure. The sampler is a container for continuously storing radioactive liquid. The larger the internal volume of the sampler, the lower the lower limit of the measurable radioactivity concentration of the device. After investigation and theoretical calculation and analysis, the volume of the sampler reaching 5L is sufficient to envelope the requirements of all types of stacks on the market.

[0054] S3: Determine the size of the scintillator detector; the detector is installed inside the lead shield and wrapped by the sampler. It is used to measure the activity concentration of the radioactive liquid continuously stored in the sampler, and to convert the radioactive signal into an electrical signal. The signal is transmitted to the in-situ radiation processor through the signal line for data processing, and finally the activity concentration level of the radioactive liquid is displayed on the interface of the in-situ radiation processor. According to the calculation of the Geant4 Monte Carlo simulation software, the crystal of the detector is 3 inches, which is enough to cover the measurement lower limit required by all types of reactors on the market. By determining the maximum size of the lead shield, the sampler and the detector, the measurement range lower limit of the low-level liquid activity monitor meets the design requirements of all types of reactors on the market.

[0055] S4: Determine the minimum detectable lower limit of the scintillator detector; the operation of steps S1-S3 ensures that the measurement range lower limit of the low-level liquid activity monitor meets the design requirements of all types of reactors on the market, at which time the sensitivity value reaches the maximum value, and the minimum detectable lower limit of the monitoring equipment is determined.

[0056] S5: A layer of shielding material is provided between the scintillator detector and the sampler, and at the same time, the thickness of the shielding material layer is gradually increased, and a first relationship curve between the thickness of the shielding material layer and the sensitivity of the scintillator detector is calculated. A first correction coefficient is calculated based on the first relationship curve, and the thickness of the shielding material layer is determined based on the first correction coefficient. In other words, shielding material such as lead, tin, copper, aluminum, etc. is added in the space reserved between the detector and the sampler. The sensitivity value gradually decreases, and the measurement lower limit of the monitoring equipment gradually increases with the increase of the thickness of the shielding body, and at the same time the measurement upper limit increases synchronously. The change trend of the sensitivity value caused by the increase of the thickness of the shielding material can be simulated and calculated by the Geant4 Monte Carlo simulation software to obtain the relationship curve. According to the relationship curve between the thickness of the shielding material and the sensitivity value, a matching correction coefficient is added to the software to realize the function of adjustable measurement range of the monitoring equipment.

[0057] S6: Adjust the size of the sampler, calculate a second relationship curve between the size of the sampler and the sensitivity of the scintillator detector, calculate a second correction coefficient based on the second relationship curve, and determine the size of the sampler based on the second correction coefficient. In other words, the size of the sampler is changed, the size is reduced, the volume of the sampler is reduced, and the sensitivity value gradually decreases. The measurement lower limit of the monitoring equipment increases with the decrease of the volume of the sampler, and at the same time the measurement upper limit increases synchronously. The change trend of the sensitivity value caused by the decrease of the volume of the sampler can be simulated and calculated by the Geant4 Monte Carlo simulation software to obtain the relationship curve. According to the relationship curve between the volume of the sampler and the sensitivity The value relation curve is synchronized to the software by adding matching correction coefficients, so that the monitoring device has a function of adjustable measurement range.

[0058] The beneficial effects of the second embodiment of the present application and various implementation manners thereof can be analyzed with reference to the beneficial effects of the first embodiment and various implementation manners thereof, which will not be described here again.

[0059] In some embodiments of the present application, the thickness of the lead shielding member is 9.5cm-10.5cm. Preferably, it is 10cm.

[0060] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, “clockwise”, “counterclockwise” and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0061] In addition, the terms “first” and “second” are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with “first” and “second” can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of “a plurality of” is two or more, unless otherwise explicitly specified and limited.

[0062] In the present application, unless otherwise explicitly specified and limited, the terms “mounting”, “connection”, “connection”, “fixing” and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0063] The above is a further detailed description of the present application in combination with specific preferred embodiments, and the specific implementation of the present application cannot be limited to these descriptions. For those skilled in the art, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be regarded as falling within the protection scope of the present application.

Claims

1. A low-level radioactive liquid activity monitoring device with adjustable measurement range, characterized in that, It includes a sampling inlet pipe, a monitoring component, and a sampling outlet pipe. The monitoring component includes a lead shield, which has a shielding cavity. A scintillator detector and a sampler are installed inside the shielding cavity. The sampler is a U-shaped component, which includes a U-shaped sampling cavity and a U-shaped groove. The sampling inlet pipe and the sampling outlet pipe are both connected to the U-shaped sampling cavity, and the detection end of the scintillator detector extends into the U-shaped groove. A shielding material layer is provided between the detection end of the scintillator detector and the inner wall of the U-shaped groove.

2. The low-level radioactive liquid activity monitoring device with adjustable measurement range according to claim 1, characterized in that, The sampling inlet pipe is equipped with a first main switch, a filter device, a water pump, a regulating valve, and a first auxiliary switch in sequence, while the sampling outlet pipe is equipped with a flow meter and a second main switch in sequence.

3. The low-level radioactive liquid activity monitoring device with adjustable measurement range according to claim 2, characterized in that, It also includes a liquid flushing inlet pipe and a liquid flushing outlet pipe. The liquid flushing inlet pipe is connected to the sampling inlet pipe and is located between the first auxiliary switch and the lead shield. The liquid flushing outlet pipe is connected to the sampling outlet pipe and is located between the flow meter and the second main switch.

4. The low-level radioactive liquid activity monitoring device with adjustable measurement range according to claim 2, characterized in that, It also includes an air-purge inlet pipe and an air-purge outlet pipe. The air-purge outlet pipe is connected to the sampling water inlet pipe and is located between the first auxiliary switch and the lead shield. The air-purge inlet pipe is connected to the sampling water outlet pipe and is located between the flow meter and the second main switch.

5. The low-level radioactive liquid activity monitoring device with adjustable measurement range according to claim 2, characterized in that, It also includes a flushing water pipe, which is connected to the sampling inlet water pipe and is located between the first main switch and the filter device.

6. The low-level radioactive liquid activity monitoring device with adjustable measurement range according to claim 2, characterized in that, It also includes a secondary pipeline, and a second auxiliary switch is provided between the filter device and the water pump. Both ends of the secondary pipeline are connected to the sampling inlet pipe, and one end of the sampling inlet pipe is located between the filter device and the water pump, while the other end of the sampling inlet pipe is located between the water pump and the regulating valve.

7. The low-level radioactive liquid activity monitoring device with adjustable measurement range according to claim 1, characterized in that, The scintillator detector is a NaI(Tl) scintillator detector.

8. The low-level radioactive liquid activity monitoring device with adjustable measurement range according to claim 1, characterized in that, It also includes on-site radiation processors, electrical junction boxes, electrical control boxes, and audible and visual alarms.

9. A method for monitoring the activity of low-level radioactive liquids with an adjustable measurement range, characterized in that, A low-level radioactive liquid activity monitoring device with adjustable measurement range as described in any one of claims 1 to 8, the low-level radioactive liquid activity monitoring device comprising a sampling inlet pipe, a monitoring component, and a sampling outlet pipe, the monitoring component comprising a lead shield, the lead shield having a shielding cavity, the shielding cavity being provided with a scintillator detector and a sampler, the method comprising: Step 1: Determine the dimensions of the lead shielding component; Step 2: Determine the structure and volume of the sampler, and set the sampler as a U-shaped structure; Step 3: Determine the dimensions of the scintillator detector; Step 4: Determine the lowest detectable limit of the scintillator detector; Step 5: Set a shielding material layer between the scintillator detector and the sampler. At the same time, gradually increase the thickness of the shielding material layer. Calculate the first relationship curve between the thickness of the shielding material layer and the sensitivity of the scintillator detector. Calculate a first correction coefficient based on the first relationship curve. Determine the thickness of the shielding material layer based on the first correction coefficient. Step 6: Adjust the size of the sampler, calculate the second relationship curve between the size of the sampler and the sensitivity of the scintillator detector, calculate the second correction coefficient based on the second relationship curve, and determine the size of the sampler based on the second correction coefficient.

10. The method for monitoring the activity of low-level radioactive liquids with adjustable measurement range according to claim 9, characterized in that, The thickness of the lead shield is 9.5cm to 10.5cm.

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