CN117607170A - Measurement method for determining shielding effect of sample on predetermined radioactive irradiation source - Google Patents
Measurement method for determining shielding effect of sample on predetermined radioactive irradiation source Download PDFInfo
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- CN117607170A CN117607170A CN202311640214.0A CN202311640214A CN117607170A CN 117607170 A CN117607170 A CN 117607170A CN 202311640214 A CN202311640214 A CN 202311640214A CN 117607170 A CN117607170 A CN 117607170A
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- 229910052751 metal Inorganic materials 0.000 description 6
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- INAHAJYZKVIDIZ-UHFFFAOYSA-N boron carbide Chemical compound B12B3B4C32B41 INAHAJYZKVIDIZ-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
Abstract
The present disclosure provides a measurement method of determining shielding effectiveness of a sample against a predetermined radioactive irradiation source, comprising: s10: providing a predetermined source of radioactive radiation; s20: starting a preset radioactive irradiation source, and irradiating a sample space to be measured; s30: measuring a first radioactivity level of the irradiation; s40: placing a sample in the sample space; s50: irradiating a sample placed in a sample space by using a predetermined radioactive irradiation source, changing the position of the sample in the sample space, and irradiating the sample for a plurality of times by using the predetermined radioactive irradiation source; s60: measuring a second radioactivity level of the radiation passing through the plurality of exposures of the sample; s70: and determining the shielding effect of the sample on the predetermined radioactive irradiation source according to the first radioactivity level and the second radioactivity level.
Description
Technical Field
At least one embodiment of the present disclosure relates to a measurement of a shielding effect of a sample on a predetermined radioactive irradiation source, and more particularly, to a measurement method of determining a shielding effect of a sample on a predetermined radioactive irradiation source.
Background
The reactor is a heat pipe reactor, for example, and is mainly used for providing power for a spacecraft, and is mainly used for scientific detection of solar system boundaries and the like. The heat pipe reactor shield body is connected with the spacecraft platform, and a plurality of components sensitive to gamma rays and neutron rays are arranged on the platform, so that the shield body is required to be arranged for reducing the neutron rays and the gamma rays generated by the reactor, and the components of the spacecraft platform are protected. The reactor itself characteristics determine that the weight of the shield cannot be too heavy and that the shield is as small as possible.
At present, a Monte Carlo calculation method is generally adopted in the design of a shielding body of a reactor to calculate the distribution situation of neutron rays and gamma rays, and the shielding effect of different materials is evaluated. However, the monte carlo calculation method has a great uncertainty, and in order to obtain the shielding effect of the complex geometry shielding body on the neutron ray or the gamma ray through complete accurate calculation, the complex geometry shielding body needs to be used as a sample, the neutron source or the gamma source is used as a predetermined radioactive irradiation source, and the shielding effect of the sample on the predetermined radioactive irradiation source is determined.
Disclosure of Invention
In order to solve at least one of the technical problems in the prior art, the disclosure provides a measuring method for determining the shielding effect of a sample on a predetermined radioactive irradiation source, which can accurately calculate the shielding effect of the sample on the predetermined radioactive irradiation source at different positions of a sample space and acquire a result on line in real time.
The present disclosure provides a measurement method for determining shielding effect of a sample on a predetermined radioactive irradiation source, comprising: s10: providing the predetermined radioactive irradiation source; s20: starting the predetermined radioactive irradiation source, and irradiating a sample space to be measured; s30: measuring a first level of radioactivity of said irradiation; s40: placing the sample in the sample space; s50: irradiating the sample placed in the sample space by using the predetermined radioactive irradiation source, changing the position of the sample in the sample space, and irradiating the sample by using the predetermined radioactive irradiation source for a plurality of times; s60: measuring a second level of radioactivity of the radiation passing through the plurality of shots of the sample; s70: and determining the shielding effect of the sample on the predetermined radioactive irradiation source according to the first radioactivity level and the second radioactivity level.
According to the measuring method for determining the shielding effect of the sample on the preset radioactive irradiation source, the preset radioactive irradiation source is started, the sample space to be measured is irradiated, the first radioactive level of irradiation is measured, the sample is placed in the sample space, the sample placed in the sample space is irradiated by the preset radioactive irradiation source, the position of the sample in the sample space is changed, the sample is irradiated for multiple times by the preset radioactive irradiation source, the second radioactive level of rays passing through the sample and subjected to multiple times of irradiation is measured, the shielding effect of the sample on the preset radioactive irradiation source is determined according to the first radioactive level and the second radioactive level, and the shielding effect of the sample on the preset radioactive irradiation source at different positions of the sample space can be accurately calculated and obtained.
Drawings
FIG. 1 is a flow chart of a method of determining a shielding effect of a sample on a predetermined radioactive irradiation source according to an exemplary embodiment of the present disclosure; and
fig. 2 is an apparatus diagram of a sample shielding a predetermined radioactive irradiation source according to an exemplary embodiment of the present disclosure.
In the drawings, the reference numerals have the following meanings:
1. a radiation unit;
2. a sample unit;
3. a detection unit;
4. and an output unit.
Detailed Description
For the purposes of promoting an understanding of the principles and advantages of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. This disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. In the drawings, relative dimensions may be exaggerated for clarity, and like reference numerals refer to like elements throughout.
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features and/or components, but do not preclude the presence or addition of one or more other features or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.
For the convenience of those skilled in the art to understand the technical solutions of the present disclosure, the following technical terms will be explained.
Where a convention analogous to "at least one of A, B and C, etc." is used, in general such a construction should be interpreted in accordance with the convention used by those skilled in the art (e.g., "a component having at least one of A, B and C" would include but not be limited to a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C components, etc.). Where a convention analogous to "at least one of A, B or C, etc." is used, in general such a construction should be interpreted in accordance with the convention used by those skilled in the art (e.g., "a component having at least one of A, B or C" should include but not be limited to components having a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.).
In order to solve the problem of uncertainty in calculating the distribution of neutron rays and gamma rays in the Monte Carlo calculation method, according to the inventive concept of one aspect of the present disclosure, a sample space to be measured is irradiated by starting a predetermined radioactive irradiation source, a first radioactivity level of the irradiation is measured, a sample is placed in the sample space, the sample placed in the sample space is irradiated by the predetermined radioactive irradiation source, the position of the sample in the sample space is changed, the sample is irradiated by the predetermined radioactive irradiation source for multiple times, a second radioactivity level of the rays passing through the sample for multiple times is measured, the shielding effect of the sample on the predetermined radioactive irradiation source is determined according to the first radioactivity level and the second radioactivity level, the shielding effect of the sample on the predetermined radioactive irradiation source can be accurately calculated, and the result can be obtained in real time on line.
Fig. 1 is a flow chart of a method of determining a shielding effect of a sample on a predetermined radioactive irradiation source according to an exemplary embodiment of the present disclosure.
According to an embodiment of the present disclosure, as shown in fig. 1, a measurement method of determining a shielding effect of a sample on a predetermined radioactive irradiation source includes the following steps S10 to S70.
Step S10: a predetermined source of radioactive radiation is provided.
According to an embodiment of the present disclosure, the predetermined radioactive irradiation source is a neutron source, a gamma source, or a combination of neutron and gamma sources.
Step S20: and starting a preset radioactive irradiation source to irradiate the sample space to be measured.
According to the embodiment of the disclosure, the predetermined radioactive irradiation source is started, neutron rays or gamma rays are emitted, and the sample space to be measured is irradiated, so that the irradiation environment where the sample is positioned can be simulated.
Step S30: a first level of radioactivity of the radiation is measured.
According to an embodiment of the present disclosure, in the case where the predetermined radioactive irradiation source is a neutron source, a first radioactivity level of neutron rays is measured in step S30. In the case where the predetermined radioactive irradiation source is a gamma source, a first radioactivity level of gamma rays is measured in step S30. In the case where the predetermined radioactive irradiation source is a combination of a neutron source and a gamma source, a first radioactivity level of the neutron ray and gamma ray combination is measured in step S30.
According to an alternative embodiment of the present disclosure, the radiation shielding material of the neutron ray may be selected from, for example, lithium hydride materials, which have advantages of low density, high melting point, and the like, and materials such as boron carbide may be selected to absorb neutrons in addition to lithium hydride.
According to alternative embodiments of the present disclosure, the radiation shielding material for gamma rays may be selected from materials such as depleted uranium, tungsten, or lead. The tungsten has good shielding effect, is easy to process and manufacture, and has smaller heating value under the irradiation condition. The depleted uranium has the advantages of easy processing, higher strength and the like, and meanwhile, the depleted uranium contains elements such as uranium and the like, so that the control force is higher.
Step S40: the sample is placed in the sample space.
According to an embodiment of the present disclosure, in the case where the predetermined radioactive irradiation source is a neutron source, the sample is a shield shielding neutron rays. In the case where the predetermined radioactive irradiation source is a gamma source, the sample is a shield shielding gamma rays. In the case where the predetermined radioactive irradiation source is a combination of a neutron source and a gamma source, the sample is a shield that shields neutron rays and gamma rays simultaneously.
Step S50: irradiating a sample placed in the sample space by using a predetermined radioactive irradiation source, changing the position of the sample in the sample space, and irradiating the sample a plurality of times by using the predetermined radioactive irradiation source.
Step S60: a second level of radioactivity of the radiation is measured over the multiple exposures of the sample.
Step S70: and determining the shielding effect of the sample on the predetermined radioactive irradiation source according to the first radioactivity level and the second radioactivity level.
According to the embodiment of the disclosure, a sample space to be measured is irradiated by starting a preset radioactive irradiation source, a first radioactive level of irradiation is measured, a sample is placed in the sample space, the sample placed in the sample space is irradiated by the preset radioactive irradiation source, the position of the sample in the sample space is changed, the sample is irradiated for multiple times by the preset radioactive irradiation source, a second radioactive level of rays passing through the sample and subjected to multiple times of irradiation is measured, the shielding effect of the sample on the preset radioactive irradiation source is determined according to the first radioactive level and the second radioactive level, the shielding effect of the sample on the preset radioactive irradiation source can be accurately calculated, and the result can be obtained in real time on line.
According to an embodiment of the present disclosure, in step S10: the predetermined radioactive irradiation source is a neutron source and a gamma source or a combination of both.
In accordance with an embodiment of the present disclosure, where the predetermined radioactive irradiation source is a neutron source, the neutron source may be selected to be, for example, a neutron reactor, and neutrons generated by the reactor may be neutrons at an energy level of 0.0625eV to 1 MeV. In the case where the predetermined radioactive irradiation source is a gamma source, the gamma source may be selected to be, for example, co-60 or the like, and Co-60 may release gamma rays having energies of 1.17MeV and 1.33MeV with a half-life of 5.27 years.
According to an embodiment of the present disclosure, the combination of neutron and gamma sources is as follows: the neutron source and the gamma source are disposed at the same location, thereby forming a combined source of the neutron source and the gamma source such that they generate neutron rays and gamma rays at the same time.
According to an embodiment of the present disclosure, in the case where the predetermined radioactive irradiation source is a combination source of a neutron source and a gamma source, the neutron source and the gamma source are disposed at the same position so that the combination source can simultaneously generate neutron rays and gamma rays.
According to an embodiment of the present disclosure, in step S50, further includes: the position of the sample in the sample space is changed in the horizontal direction, the vertical direction and the rotation direction.
According to an embodiment of the present disclosure, the horizontal direction is a horizontal extending direction along a radiation emitting direction of a predetermined radioactive irradiation source, the vertical direction is a direction orthogonal to the horizontal extending direction, and the rotating direction is a direction rotating in a circumferential direction centering around the horizontal extending direction.
According to the embodiment of the disclosure, by changing the position of the sample in the sample space in the horizontal direction, the vertical direction and the rotation direction, shielding of the radiation of the predetermined radioactive irradiation source from a plurality of different positions of the sample in the sample space can be achieved.
According to an embodiment of the present disclosure, in step S50, further includes: the relative position of the sample and the predetermined radioactive irradiation source, and the monitoring device, is changed over the sample space.
According to the embodiment of the disclosure, the position of the sample in the sample space is changed, and meanwhile, the relative positions of the sample and the predetermined radioactive irradiation source and the sample and the monitoring device are changed, so that the radioactive rays emitted by the radioactive irradiation source can pass through the sample, one part of the radioactive rays is shielded by the sample, and the other part of the radioactive rays is detected by the monitoring device.
According to alternative embodiments of the present disclosure, the monitoring device may select, for example, a detector that detects the radioactivity level of neutron rays, a detector that detects the radioactivity level of gamma rays, and a detector that may detect both neutron rays and gamma rays.
According to an embodiment of the present disclosure, in step S60, further includes: the detector for detecting the radioactivity level is arranged so that the detector can receive radiation from multiple positions, directions, and angles.
According to the embodiment of the disclosure, the detector for detecting the radioactivity level is arranged according to the position of the sample in the sample space, so that the detector receives the radioactive rays from the preset radioactive irradiation source after passing through the sample in a full range, and the multi-dimensional detection of the detector can be realized.
In accordance with embodiments of the present disclosure, where the predetermined radioactive irradiation source is a neutron source, the detector may be selected to be, for example, a BF3 proportional counter, a boron-coated proportional counter, or a fissile counter, preferably a BF3 proportional counter.
According to the embodiment of the disclosure, the BF3 proportional counter tube is formed by a metal round tube, an insulated thin wire is suspended along the central axis of the round tube to serve as the other electrode, and BF3 gas is filled in the metal round tube. The neutrons and the alpha particles emitted by the boron effect produce primary ionization of the gas. The polarization voltage applied to the thin wire is about 3000V, and secondary ionization can be generated to increase the ion logarithm generated, so that the detection sensitivity is improved. The pulse height generated by neutrons is about 100 times the pulse height generated by gamma rays, so that interference of gamma rays can be reduced by pulse height discrimination. The maximum counting rate of the BF3 proportional counter is 5 multiplied by 10n/s.
According to the embodiment of the disclosure, the boron-coated proportional counting tube is formed by coating solid boron on the tube wall of the counting tube, wherein a shell is made of aluminum, argon is filled in the shell, and an electrode with a thin wire is arranged at the center. It is connected to a high voltage power supply to obtain the higher electric field strength required for gas discharge. The boron-coated proportional counter tube has longer service life and better recovery condition after high neutron fluence rate irradiation.
According to an embodiment of the present disclosure, the fission counter tube is a fission phenomenon to which uranium is applied. Uranium is coated on the electrode of the counting tube, and inert gas is filled in the tube. After neutron irradiation, the fragments generated by uranium fission have high energy and enough ionization capacity to generate proper pulse amplitude. When the capacitance is 100pF, the pulse amplitude is in the range of 0.1-1 mV. The sensitivity of the fission counting tube is about 0.2 counts per unit neutron fluence rate. The fissile counting tube is characterized by being operable in a very intense gamma-ray field (up to 10 Sv/h) and at temperatures up to 900 ℃.
In accordance with embodiments of the present disclosure, where the predetermined radioactive irradiation source is a gamma source, the detector may be selected from, for example, scintillation counting tubes and geiger-mueller counting tubes.
According to an embodiment of the present disclosure, a scintillation counter mainly includes a scintillator, a light collection system, and a photomultiplier tube. The scintillator material is a substance capable of emitting light when irradiated with radiation, and is classified into an inorganic scintillator and an organic scintillator, and may exist in a solid, liquid, and gaseous state. The light collection system is the connection between the scintillator and the photomultiplier tube. The two sides of the light source are required to be respectively consistent with the shape of the light output part of the scintillator and the shape of the light input part of the photomultiplier, so as to achieve the purposes of collecting as much light as possible and uniformly distributing the light. Photomultiplier tubes are optoelectronic devices that convert a photon stream into an electron stream using the photoelectric effect and amplify the electron stream using a secondary electron emission phenomenon. It comprises photocathode, holding anode, and sealing them in a vacuum glass tube.
According to embodiments of the present disclosure, where the detector is a scintillation counter, gamma rays interact with a scintillator in the scintillation counter, ionizing or exciting atoms, molecules of the scintillator, and the excited atoms, molecules emit photons when de-excited. Photons are collected as much as possible onto the photocathode of the photomultiplier by means of the reflecting substance and the light guide, and due to the photoelectric effect photons strike photoelectrons on the photocathode. The photoelectrons are multiplied in a photomultiplier tube, and the multiplied electron flow produces an electrical signal on an anode load, which is amplified, analyzed and recorded by electronics.
According to embodiments of the present disclosure, geiger-mueller-counting tubes are made according to the ability of the radiation energy to ionize the gas. The metal tube with two ends sealed by insulating material has low pressure gas stored therein, metal wire is installed along the axis of the tube, a certain voltage (lower than the breakdown voltage of the gas in the tube) is generated between the metal wire and the tube wall by the battery pack, and the gas is not discharged when no ray passes through the tube. When a high-speed particle of gamma ray enters the tube, the gas atoms in the tube can be ionized, a plurality of free electrons are released, and the free electrons fly to the metal wire under the action of voltage. The multiple electrons ionize other atoms of the gas along the way, releasing more electrons. More and more electrons are ionized in succession to more and more gas atoms, so that the gas in the tube becomes a conductor, and a rapid gas discharge phenomenon is generated between the filament and the tube wall. So that there is a pulsed current input to the amplifier and a counter coupled to the output of the amplifier. The counter automatically records the discharge of each particle as it flies into the tube, whereby the number of particles can be detected.
According to an embodiment of the present disclosure, the detectors are arranged such that the plurality of detectors are arranged radially with respect to the sample, and a line connecting the position points at which the plurality of detectors are arranged is arc-shaped.
According to the embodiment of the disclosure, the plurality of detectors are placed radially relative to the sample, and the connecting lines between the position points where the plurality of detectors are arranged are arc-shaped, so that the detectors can receive and detect radiation in multiple dimensions.
According to an embodiment of the present disclosure, in step S60, the weight of the measurement results obtained by the plurality of detectors in determining the second radioactivity level is set to be different.
According to the embodiment of the disclosure, the weights of the measurement results obtained by the plurality of detectors in determining the second radioactivity level are set to be different, so that the second radioactivity level can be balanced as the measurement results of the plurality of detectors at different positions in the sample space.
According to embodiments of the present disclosure, the weight of the measurement results of the detector is higher in the area swept by the extension line of the detector, which is shifted up and down along the predetermined angle, between the position point of the predetermined radioactive irradiation source and the position point of the sample, according to the top view of the sample and the arrangement of the detector, than the weight of the measurement results of the detector at other positions.
According to an embodiment of the present disclosure, the area swept up and down along the predetermined angle is an area offset up by 30 ° and offset down by between 30 ° with reference to an extension line connecting between a position point of the predetermined radioactive irradiation source and a position point of the sample to the detector.
According to the embodiments of the present disclosure, the radiation detected by the detector in the area swept along the predetermined angle is more than the radiation detected by the detectors at other positions, and therefore, the measurement result of the detector in the area swept along the predetermined angle is weighted more than the measurement result of the detector at other positions, so that the accuracy of the second radioactivity level measurement can be increased.
According to an embodiment of the present disclosure, the shielding effect of the nth detector measurement determined radioactivity can be expressed by the following formula (1):
wherein eta n Is the shielding effect of the nth detector for measuring the determined radioactivity,is the second radioactivity level determined by the n-th detector measurement after passing the sample,/->Is the first radioactivity level determined without measurement by the nth detector of the sample.
According to an embodiment of the present disclosure, a first radioactivity level determined without an nth detector measurement of a sample and a second radioactivity level determined with an nth detector measurement after the sample are set as a control group, thereby determining a shielding effect of the radioactivity determined with the nth detector measurement.
According to an embodiment of the present disclosure, the determined radioactivity shielding effect of n detectors in the area swept up and down along the predetermined angle is pη n The shielding effect of the radioactivity determined by the measurement of n detectors is eta Inner part ，η Inner part Can be represented by the following formula (2):
η inner part ＝(pη 1 +…+pη n )/n (2)；
The determined radioactivity shielding effect of m detectors outside the area swept along the predetermined angle is qη m The measured and determined radioactivity of m detectors has a shielding effect of eta Outer part ，η Outer part Can be represented by the following formula (3):
η outer part ＝(qη 1 +…+qη m )/m (3)；
The shielding effect of the determined radioactivity of all detectors is eta Total (S) ，η Total (S) Can be represented by the following formula (4):
η total (S) ＝aη Inner part +bη Outer part (4)
Where a and b are weight parameters.
According to an embodiment of the present disclosure, a is a weight parameter of the shielding effect of the determined radioactivity of n detectors within the area swept along the predetermined angle offset up and down, and b is a weight parameter of the shielding effect of the determined radioactivity of m detectors outside the area swept along the predetermined angle offset up and down. The preset angle can be set according to the actual situation by a person skilled in the art, and the values of the weight parameters a and b can be determined according to the actual situation and experience by the person skilled in the art.
According to the embodiments of the present disclosure, the shielding effect of the determined radioactivity of n detectors in the area swept along the predetermined angle offset up and down and the shielding effect of the determined radioactivity of m detectors outside the area swept along the predetermined angle offset up and down are averaged, respectively, so that the balance of the shielding effects of the determined radioactivity of all the detectors can be achieved.
Fig. 2 is an apparatus diagram of a sample shielding a predetermined radioactive irradiation source according to an exemplary embodiment of the present disclosure.
According to an embodiment of another aspect of the present disclosure, as shown in fig. 2, the radiation unit 1 is adapted to irradiate a sample space to be measured and irradiate the sample after placing the sample in the sample space, thereby generating neutron rays or gamma rays. The sample unit 2 is adapted to hold a sample, which may be a shield shielding neutron rays, a shield shielding gamma rays or a shield shielding both neutron rays and gamma rays. The detection unit 3 is adapted to detect a first radioactivity level and a second radioactivity level of the radiation subjected to multiple irradiations of the sample, and the output unit 4 is adapted to receive the detection result of the detection unit 3 and to calculate the shielding effect of the sample on the predetermined radioactive irradiation source.
According to an embodiment of the present disclosure, in the case where the predetermined radiation source in the radiation unit 1 is a neutron reactor, a neutron extraction passage is provided outside the neutron reactor to extract neutrons from the reactor, and a collimator is provided, which is adapted to screen neutrons in a preset direction.
According to alternative embodiments of the present disclosure, the sample may be configured to consist of a plurality of coaxially disposed annular cylinders with the gamma shielding material and neutron shielding material alternately disposed.
It should be further noted that, the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "rear", "left", "right", etc., are only referring to the directions of the drawings, and are not intended to limit the scope of the present disclosure. Throughout the drawings, like components are denoted by like or similar reference numerals. In the event that an understanding of the present disclosure may be made, conventional structures or constructions will be omitted, and the shapes and dimensions of the various parts in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure.
Unless otherwise known, numerical parameters in this specification and the appended claims are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. In particular, all numbers expressing dimensions and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". In general, the meaning of expression is meant to include a variation of + -10% in some embodiments, a variation of + -5% in some embodiments, a variation of + -1% in some embodiments, and a variation of + -0.5% in some embodiments by a particular amount.
The use of ordinal numbers such as "first," "second," "third," etc., in the description and in the claims to modify a corresponding element does not by itself connote any ordinal number of elements and does not by itself connote ordering of one element from another, but rather the ordinal numbers are used merely to distinguish one element having a certain name from another element having a same name.
Furthermore, unless specifically described or steps must occur in sequence, the order of the above steps is not limited to the list above and may be changed or rearranged according to the desired design. In addition, the above embodiments may be mixed with each other or other embodiments based on design and reliability, i.e. the technical features of the different embodiments may be freely combined to form more embodiments.
While the foregoing is directed to embodiments of the present disclosure, other and further details of the invention may be had by the present application, it is to be understood that the foregoing description is merely exemplary of the present disclosure and that no limitations are intended to the scope of the disclosure, except insofar as modifications, equivalents, improvements or modifications may be made without departing from the spirit and principles of the present disclosure.
Claims (11)
1. A measurement method for determining the shielding effect of a sample on a predetermined radioactive irradiation source, comprising:
s10: providing the predetermined radioactive irradiation source;
s20: starting the predetermined radioactive irradiation source, and irradiating a sample space to be measured;
s30: measuring a first radioactivity level of the irradiation;
s40: placing the sample in the sample space;
s50: irradiating the sample placed in the sample space by using the predetermined radioactive irradiation source, changing the position of the sample in the sample space, and irradiating the sample for a plurality of times by using the predetermined radioactive irradiation source;
s60: measuring a second level of radioactivity of the radiation passing through the plurality of shots of the sample;
s70: and determining the shielding effect of the sample on the predetermined radioactive irradiation source according to the first radioactivity level and the second radioactivity level.
2. The measurement method according to claim 1, wherein,
in step S50, further comprising:
the position of the sample in the sample space is changed in the horizontal direction, the vertical direction and the rotational direction.
3. The measurement method according to claim 2, wherein,
in step S50, further comprising:
changing the relative position of the sample and the predetermined radioactive irradiation source, and the monitoring device, over the sample space.
4. The measurement method according to claim 1, wherein,
in step S60, further comprising:
the detector for detecting the radioactivity level is arranged so that it can receive radiation from multiple positions, directions, angles.
5. The measurement method according to claim 4, wherein,
the detector is arranged to:
the plurality of detectors are arranged radially relative to the sample, and a connecting line between the position points where the plurality of detectors are arranged is in an arc shape.
6. The measurement method according to claim 5, wherein,
in step S60, the weight of the measurement results obtained by the plurality of detectors in determining the second radioactivity level is set to be different.
7. The measurement method according to claim 6, wherein a weight of a measurement result of the detector in a region swept by an extension line of the detector shifted up and down along a predetermined angle is higher than that of measurement results of the detectors at other positions, which are connected between a position point of the predetermined radioactive irradiation source and a position point of the sample, according to a top view of the sample and the arrangement of the detector.
8. The measurement method according to claim 1, wherein,
in step S10:
the predetermined radioactive irradiation source is a neutron source and a gamma source or a combination of both.
9. The measurement method according to claim 8, wherein,
the neutron source and gamma source combination adopts the following modes:
the neutron source and the gamma source are disposed at the same location, thereby forming a combined source of the neutron source and the gamma source such that they produce neutron rays and gamma rays simultaneously.
10. The measurement method according to claim 7, wherein,
η n is the shielding effect of the nth detector for measuring the determined radioactivity,is the second radioactivity level determined by the n-th detector measurement after passing the sample,/->Is the first radioactivity level determined without measurement by the nth detector of the sample.
11. The measurement method according to claim 10, wherein,
η inner part ＝(pη 1 +…+pη n )/n；
The determined radioactivity shielding effect of n detectors in the area swept up and down along the predetermined angle is peta n The shielding effect of the radioactivity determined by the measurement of n detectors is eta Inner part ；
η Outer part ＝(qη 1 +…+qη m )/m；
The determined radioactivity shielding effect of m detectors outside the area swept along the predetermined angle is qη m The measured and determined radioactivity of m detectors has a shielding effect of eta Outer part ；
η Total (S) ＝aη Inner part +bη Outer part ；
a and b are weight parameters.
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