CN212965440U - Gamma-beta composite detecting device - Google Patents
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- CN212965440U CN212965440U CN202021461726.2U CN202021461726U CN212965440U CN 212965440 U CN212965440 U CN 212965440U CN 202021461726 U CN202021461726 U CN 202021461726U CN 212965440 U CN212965440 U CN 212965440U
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Abstract
The utility model belongs to the technical field of nuclear power maintenance, concretely relates to compound detection device of gamma-beta. The absorptivity of the first scintillation crystal to beta rays is higher than that to gamma rays, so that the first photomultiplier and the first signal processing unit can detect the beta rays according to the light rays emitted by the first scintillation crystal, the absorptivity of the second scintillation crystal to the beta rays is lower than that to the gamma rays, the second photomultiplier and the second signal processing unit can detect the gamma rays according to the light rays emitted by the second scintillation crystal, and therefore composite detection of the gamma rays and the beta rays is achieved, and the damage condition of the fuel assembly at different stack-out times can be judged in an auxiliary mode. In addition, the first scintillation crystal is used as a detection chamber, so that the gas to be detected is effectively stored, and the first scintillation crystal can be more fully irradiated by the rays released by the gas to be detected from inside to outside, so that the gamma-beta composite detection device can more sensitively detect the beta rays released by the gas to be detected.
Description
Technical Field
The utility model belongs to the technical field of nuclear power maintenance, concretely relates to compound detection device of gamma-beta.
Background
The most efficient way to detect the breakage of nuclear fuel assemblies is to detect the radioactive fission gas released to the outside, and the fissile materials in the fuel assemblies are mainly Xe-133, Kr-85, I-131, Cs-136, Cs-134, CS-137 and isotopes of these elements, wherein the gaseous fission products which are not easily soluble in water are mainly Xe-133 and Kr-85 and isotopes thereof. The gamma ray decay branch ratio of Xe-133 is large, and the gamma ray can be detected to find an obvious energy characteristic peak so as to determine the Xe-133 and the radioactivity thereof, but the half-life is short, so that the damage condition of a fuel assembly with long reactor discharge time is difficult to determine by measuring the Xe-133 nuclide. Kr-85 has a long half-life period and can be used as a judgment basis for the damage condition of a fuel assembly with long stacking time, but the gamma decay branch ratio of Kr-85 is small, so that an obvious energy characteristic peak is difficult to detect through gamma rays, beta rays are continuous spectrums, and quantitative and qualitative analysis is difficult to perform on radioactive substances when various radioactive substances exist. Therefore, there is a need for effective detection of the radioactivity of nuclear fuel assemblies that have long stack-out times.
SUMMERY OF THE UTILITY MODEL
In order to overcome the problems in the related art, a gamma-beta composite detection device is provided.
According to an aspect of an embodiment of the present disclosure, there is provided a gamma-beta composite detecting apparatus including: the device comprises a first photomultiplier, a second photomultiplier, a first scintillation crystal, a second scintillation crystal, a first signal processing unit and a second signal processing unit;
a cavity is arranged in the first scintillation crystal and used for storing gas to be detected, and the surface of one side of the second scintillation crystal is tightly attached to the surface of the first scintillation crystal;
an incident window of the first photomultiplier tube is tightly attached to the surface of the first scintillation crystal;
the incident window of the second photomultiplier is tightly attached to the other side surface of the second scintillation crystal;
the first scintillation crystal emits light under the condition of being irradiated by beta and/or gamma rays, the absorptivity of the first scintillation crystal to the beta rays is higher than that to the gamma rays, the first photomultiplier tube generates an electric signal according to the light emitted by the first scintillation crystal, and the first signal processing unit is connected with the first photomultiplier tube and used for generating a map for identifying the beta rays according to the electric signal generated by the first photomultiplier tube;
the second scintillation crystal emits light under the condition of being irradiated by beta and/or gamma rays, the absorptivity of the second scintillation crystal to the beta rays is lower than that to the gamma rays, the second photomultiplier generates an electric signal according to the light emitted by the second scintillation crystal, and the second signal processing unit is connected with the second photomultiplier and used for generating a map for identifying the gamma rays according to the electric signal generated by the second photomultiplier.
In one possible implementation, the outer wall of the first scintillation crystal is shaped as a sphere, and the inner wall of the chamber of the first scintillation crystal is shaped as a sphere.
In one possible implementation, the sphere formed by the outer wall of the first scintillation crystal is concentric with the sphere formed by the inner wall of the chamber of the first scintillation crystal.
In a possible implementation manner, one side surface of the second scintillation crystal is a spherical surface, and the spherical surface is concentric with a sphere formed by the outer wall of the first scintillation crystal;
the other side surface of the second scintillation crystal is a plane parallel to the tangent plane of one side surface of the second scintillation crystal.
In one possible implementation, the axial cross-section of the second scintillation crystal is a trapezoidal cross-section with the longer base of the trapezoidal cross-section located on one side surface of the second scintillation crystal and the shorter base of the trapezoidal cross-section located on the other side surface of the second scintillation crystal.
In one possible implementation, the first scintillating crystal comprises a plastic scintillator.
In one possible implementation, the second scintillation crystal includes sodium iodide or lanthanum bromide.
In one possible implementation, the γ - β complex detection apparatus: a gas processing unit;
the gas processing unit is communicated with the chamber of the first scintillation crystal and is used for processing gas input into the chamber of the first scintillation crystal.
In one possible implementation, the gas treatment unit comprises: the device comprises an air inlet, a filter, a dryer, a refrigerator, an ion trap and an air outlet;
the filter is communicated with the gas inlet and is used for filtering solid particles, gaseous iodine and gaseous cesium of the gas input from the gas inlet;
the dryer is connected with the filter and is used for filtering the water vapor of the gas output by the filter;
the refrigerator is connected with the dryer and used for cooling the gas output by the dryer;
the ion trap is connected with the refrigerator and is used for filtering charged ions of the gas output by the refrigerator;
one end of the gas outlet is connected with the ion trap, the other end of the gas outlet is connected with the chamber, and gas output by the ion trap is input into the chamber through the gas outlet.
In one possible implementation mode, the gamma-beta composite detection device is wrapped with a lead chamber.
The beneficial effects of the utility model reside in that: in the embodiment of the disclosure, the absorptivity of the first scintillation crystal to beta rays is higher than that to gamma rays, so that the first photomultiplier tube and the first signal processing unit can detect the beta rays according to the light emitted by the first scintillation crystal, and the absorptivity of the second scintillation crystal to the beta rays is lower than that to the gamma rays, so that the second photomultiplier tube and the second signal processing unit can detect the gamma rays according to the light emitted by the second scintillation crystal, thereby realizing the composite detection of the gamma rays and the beta rays, realizing the quantitative and qualitative analysis of radioactive gases such as Xe-133 and Kr-85, and being capable of assisting in judging the damage condition of the fuel assembly at different stacking time. In addition, the first scintillation crystal is used as a detection chamber, so that the gas to be detected is effectively stored, and the first scintillation crystal can be more fully irradiated by the rays released by the gas to be detected from inside to outside, so that the gamma-beta composite detection device can more sensitively detect the beta rays released by the gas to be detected.
Drawings
Fig. 1 is a schematic diagram illustrating a gamma-beta composite detection device according to an exemplary embodiment.
Fig. 2 is a block diagram illustrating a gamma-beta composite detection device according to an exemplary embodiment.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Generally speaking, for a fuel assembly with short discharge time, the content of Xe-133 gas is high, and the radioactivity of the fuel assembly can be analyzed by detecting gamma rays to find an energy characteristic peak of the Xe-133.
The nuclides released in the damaged fuel assembly are mainly as follows: xe-133, Kr-85, I-131, Cs-136, Cs-134, Cs-137 and isotopes of Xe and Kr, most of the rest nuclides are medium and short in service life, most nuclides decay completely within about one week after the nuclides are discharged, the isotope half-lives of the Xe and Kr nuclides are generally too short, the nuclear fuel assembly basically does not exist in the assembly after the nuclide is discharged for two months, the I-131 half-life period is 8.02d, the Cs-134 half-life period is 752.63d, and the Cs-137 half-life period is 11013d, but the nuclides are isotopes which are easily soluble in water, and once the fuel assembly is damaged, most of the leaked I-131, Cs-134 and Cs-137 can be retained in the coolant. The most predominant gaseous species in the gas to be examined is Kr-85 for long-term storage of the fuel assembly. Therefore, for fuel assemblies with long reactor discharge time, the Kr-85 nuclide can be detected, the gamma decay branching ratio of Kr-85 is only 0.43%, an obvious characteristic peak is difficult to detect, and the Kr-85 can be analyzed by detecting beta rays.
Fig. 1 is a schematic diagram illustrating a gamma-beta composite detection device according to an exemplary embodiment. As shown in fig. 1, the γ - β complex detection apparatus may include: a first photomultiplier 2, a second photomultiplier 3, a first scintillation crystal 5, a second scintillation crystal 4, a first signal processing unit (not shown in the figure), a second signal processing unit (not shown in the figure);
the first scintillation crystal 5 has a cavity 6 inside, the cavity 6 is used for storing a gas to be measured, one side surface of the second scintillation crystal 4 is tightly attached to the surface of the first scintillation crystal 5, the first scintillation crystal 5 and the second scintillation crystal 4 may have any shape, such as a cuboid, a cylinder, or a polyhedron, for example, the shape of the cavity of the first scintillation crystal 5 may also be any shape, such as a cuboid, a cylinder, or a polyhedron, and the shapes of the first scintillation crystal 5 and the second scintillation crystal 4 may be the same or different.
The first scintillation crystal 5 can emit light when irradiated with beta and/or gamma radiation, the first scintillation crystal 5 having a higher absorptivity for beta radiation than for gamma radiation, e.g., the first scintillation crystal can be made of a material that is a plastic scintillator having an absorption efficiency for beta radiation that is about 100 times higher than for gamma radiation. (the material of the first scintillation crystal is not limited in the embodiment of the present disclosure, as long as the material has a higher absorptivity for β -rays than for γ -rays), the incident window of the first photomultiplier tube 2 is in close contact with the surface of the first scintillation crystal 5, the first photomultiplier tube 2 generates an electrical signal from the light emitted by the first scintillation crystal 5, the first signal processing unit is connected to the first photomultiplier tube 2, it is considered that only long-cycle Kr-85 is substantially contained due to internal fission gas in the fuel assembly with a long stacking time, and Kr-85 mainly emits β -rays, and further, the first scintillation crystal has a higher absorptivity for β -rays than for γ -rays, so that the first signal processing unit can generate a spectrum for identifying β -rays from the electrical signal generated by the first photomultiplier tube. Therefore, the first scintillation crystal, the first photomultiplier and the first signal processing unit can be mainly used for detecting the beta rays of the fuel assembly with a long stacking time.
The second scintillation crystal 4 can emit light when irradiated with β and/or γ rays, and the second scintillation crystal 4 has a lower absorption rate for β rays than for γ rays, for example, the material of the second scintillation crystal may be NaI (sodium iodide), LaBr3 (lanthanum bromide), or the like (the material of the second scintillation crystal is not limited by the disclosed embodiment as long as the material has a lower absorption rate for β rays than for γ rays). The incident window of the second photomultiplier 3 is closely attached to the other side surface of the second scintillation crystal 4, the second photomultiplier 3 generates an electric signal according to light emitted by the second scintillation crystal 4, and the second signal processing unit is connected with the second photomultiplier 3. Because a plurality of radioactive nuclides release gamma rays in the fuel assembly with short reactor outlet time, the gamma rays of specific nuclides have specific energy values, obvious peak values can be presented on the map of the second signal processing unit to determine which nuclide is, the beta rays can only form continuous graphs without peak values, and the absorption efficiency of the second scintillation crystal on the beta rays is not high, the absorption efficiency on the gamma rays is high, and the measurement signals of the second photomultiplier on the beta rays can be used as radioactivity background to exist in the measurement signals of the second photomultiplier on the gamma rays, so that the second signal processing unit can generate the map for identifying the gamma rays according to the electric signals generated by the second photomultiplier. Therefore, the second scintillation crystal, the second photomultiplier and the second signal processing unit can be mainly used for detecting gamma rays of fuel assemblies with short stack discharging time.
In the embodiment of the disclosure, the absorptivity of the first scintillation crystal to beta rays is higher than that to gamma rays, so that the first photomultiplier tube and the first signal processing unit can detect the beta rays according to the light emitted by the first scintillation crystal, and the absorptivity of the second scintillation crystal to the beta rays is lower than that to the gamma rays, so that the second photomultiplier tube and the second signal processing unit can detect the gamma rays according to the light emitted by the second scintillation crystal, thereby realizing the composite detection of the gamma rays and the beta rays, realizing the quantitative and qualitative analysis of radioactive gases such as Xe-133 and Kr-85, and being capable of assisting in judging the damage condition of the fuel assembly at different stacking time. In addition, the first scintillation crystal is used as a detection chamber, so that the gas to be detected is effectively stored, and the first scintillation crystal can be more fully irradiated by the rays released by the gas to be detected from inside to outside, so that the gamma-beta composite detection device can more sensitively detect the beta rays released by the gas to be detected.
In one possible implementation, the outer wall of the first scintillation crystal may be spherical in shape, and the inner wall of the chamber of the first scintillation crystal may also be spherical in shape. For example, the sphere formed by the outer wall of the first scintillation crystal is concentric with the sphere formed by the inner wall of the chamber of the first scintillation crystal, so that the area of the first scintillation crystal irradiated by the radiation can be effectively increased, the sensitivity of the first scintillation crystal for detecting the radiation can be increased, the volume of the chamber for storing the gas can be increased, and in an example, the efficiency of the first scintillation crystal for detecting the beta ray can be improved to more than 50%.
In one possible implementation, in the case where the first scintillation crystal has a spherical shape in its outer shape, one side surface of the second scintillation crystal may be machined into a spherical surface, which may be concentric with the first scintillation crystal outer shape; the other side surface of the second scintillation crystal is a plane parallel to the tangent plane of one side surface of the second scintillation crystal. Like this, can effectual increase second scintillation crystal receive the area of ray irradiation, the one side that first scintillation crystal was hugged closely to second scintillation crystal can be laminated with first crystal surface more, increases the sensitivity that second scintillation crystal detected the ray.
In one possible implementation, the axial cross-section of the second scintillation crystal can be a trapezoidal cross-section with the longer base of the trapezoidal cross-section located on one side surface of the second scintillation crystal and the shorter base of the trapezoidal cross-section located on the other side surface of the second scintillation crystal.
In a possible implementation manner, the lead chamber 1 may be wrapped outside the first photomultiplier tube 2, the second photomultiplier tube 3, the first scintillation crystal 5, and the second scintillation crystal 4, and the lead chamber may shield external radiation rays, so as to further improve the accuracy of detection.
Fig. 2 is a block diagram illustrating a gamma-beta composite detection device according to an exemplary embodiment. As shown in fig. 2, the γ - β complex detection apparatus may further include: a gas processing unit.
The gas processing unit is communicated with the chamber of the first scintillation crystal and is used for processing gas introduced into the chamber of the first scintillation crystal;
as shown in fig. 2, the gas processing unit may include: the device comprises an air inlet, a filter, a dryer, a refrigerator, an ion trap and an air outlet;
the filter is communicated with the gas inlet and is used for filtering solid particles, gaseous iodine and gaseous cesium of the gas input from the gas inlet;
the dryer is connected with the filter and is used for filtering the water vapor of the gas output by the filter;
the refrigerator is connected with the dryer and is used for cooling the gas discharged by the dryer;
the ion trap is connected with the refrigerator and is used for filtering charged ions in the refrigerator.
For example, the gas to be detected enters the detection device from the gas inlet and first reaches the gas processing unit;
the gas to be measured firstly passes through a filter in a gas treatment unit, and solid particles and active gases such as iodine, cesium and the like are filtered;
gas to be detected passes through the dryer, water vapor and iodine and cesium dissolved in the water vapor are filtered, and interference of active gas such as iodine and cesium on detection results can be effectively avoided;
the gas to be detected passes through a refrigerant, the gas is cooled, and water vapor in the gas is further filtered to prepare for entering the detection unit;
the gas to be measured passes through an ion trap to filter charged ions in the gas;
the gas to be detected enters a detection air cavity (an example of a cavity of a first scintillation crystal), a gamma detector (an example of the first scintillation crystal and a first photomultiplier tube) and a beta detector (an example of the first scintillation crystal and a first photomultiplier tube) respectively detect gamma rays and beta particles in the air cavity, a detection signal of the gamma detector enters a gamma spectrometer (an example of a second signal processing unit) to form a spectrum for identifying the gamma rays, and a detection signal of the beta detector enters a beta signal processing unit to form a spectrum for identifying the beta rays.
If the fuel assembly with short reactor discharge time is aimed at, analyzing an energy characteristic peak on a gamma spectrum to realize the analysis of the Xe-133 nuclide;
if the fuel assembly with longer reactor discharge time is used, the beta total count is detected and the gamma detector is assisted to perform energy spectrum analysis, so that the influence of the activity of interfering nuclides can be eliminated, and the quantitative analysis of Kr-85 is realized
The radioactive signal processing unit formed by the two parts jointly processes the beta and gamma pulse electric signals transmitted by the detector through analog signal processing, digital-to-analog conversion and digital signal processing to form an analyzable energy map.
Having described embodiments of the present disclosure, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein were chosen in order to best explain the principles of the embodiments, the practical application, or technical improvements to the techniques in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (10)
1. A gamma-beta composite detection apparatus, characterized in that the gamma-beta composite detection apparatus comprises: the device comprises a first photomultiplier, a second photomultiplier, a first scintillation crystal, a second scintillation crystal, a first signal processing unit and a second signal processing unit;
a cavity is arranged in the first scintillation crystal and used for storing gas to be detected, and the surface of one side of the second scintillation crystal is tightly attached to the surface of the first scintillation crystal;
an incident window of the first photomultiplier tube is tightly attached to the surface of the first scintillation crystal;
the incident window of the second photomultiplier is tightly attached to the other side surface of the second scintillation crystal;
the first scintillation crystal emits light under the condition of being irradiated by beta and/or gamma rays, the absorptivity of the first scintillation crystal to the beta rays is higher than that to the gamma rays, the first photomultiplier tube generates an electric signal according to the light emitted by the first scintillation crystal, and the first signal processing unit is connected with the first photomultiplier tube and used for generating a map for identifying the beta rays according to the electric signal generated by the first photomultiplier tube;
the second scintillation crystal emits light under the condition of being irradiated by beta and/or gamma rays, the absorptivity of the second scintillation crystal to the beta rays is lower than that to the gamma rays, the second photomultiplier generates an electric signal according to the light emitted by the second scintillation crystal, and the second signal processing unit is connected with the second photomultiplier and used for generating a map for identifying the gamma rays according to the electric signal generated by the second photomultiplier.
2. The gamma-beta composite detection device according to claim 1, wherein the outer wall of the first scintillation crystal is shaped as a sphere and the inner wall of the chamber of the first scintillation crystal is shaped as a sphere.
3. The gamma-beta composite detection device according to claim 2, wherein the sphere formed by the outer wall of the first scintillation crystal is concentric with the sphere formed by the inner wall of the chamber of the first scintillation crystal.
4. The gamma-beta composite detection device according to claim 2, wherein one side surface of the second scintillation crystal is a spherical surface which is concentric with a sphere formed by the outer wall of the first scintillation crystal;
the other side surface of the second scintillation crystal is a plane parallel to the tangent plane of one side surface of the second scintillation crystal.
5. The gamma-beta composite detection device according to claim 1, wherein the axial cross section of the second scintillation crystal is a trapezoidal cross section, the longer base of the trapezoidal cross section being located on one side surface of the second scintillation crystal, and the shorter base of the trapezoidal cross section being located on the other side surface of the second scintillation crystal.
6. The gamma-beta composite detection device according to claim 1, wherein the first scintillating crystal comprises a plastic scintillator.
7. The gamma-beta composite detection device according to claim 1, wherein the second scintillation crystal comprises sodium iodide or lanthanum bromide.
8. The gamma-beta composite detection device according to claim 1, further comprising: a gas processing unit;
the gas processing unit is communicated with the chamber of the first scintillation crystal and is used for processing gas input into the chamber of the first scintillation crystal.
9. The gamma-beta composite detection device according to claim 8, wherein said gas processing unit comprises: the device comprises an air inlet, a filter, a dryer, a refrigerator, an ion trap and an air outlet;
the filter is communicated with the gas inlet and is used for filtering solid particles, gaseous iodine and gaseous cesium of the gas input from the gas inlet;
the dryer is connected with the filter and is used for filtering the water vapor of the gas output by the filter;
the refrigerator is connected with the dryer and used for cooling the gas output by the dryer;
the ion trap is connected with the refrigerator and is used for filtering charged ions of the gas output by the refrigerator;
one end of the gas outlet is connected with the ion trap, the other end of the gas outlet is connected with the chamber, and gas output by the ion trap is input into the chamber through the gas outlet.
10. The gamma-beta composite detection device according to claim 1, wherein the gamma-beta composite detection device is externally wrapped with a lead chamber.
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| CN202021461726.2U CN212965440U (en) | 2020-07-23 | 2020-07-23 | Gamma-beta composite detecting device |
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| CN202021461726.2U CN212965440U (en) | 2020-07-23 | 2020-07-23 | Gamma-beta composite detecting device |
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| CN212965440U true CN212965440U (en) | 2021-04-13 |
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