A plant seed 241 Am- 9 Dose distribution device for Be source neutron irradiation

Abstract

The application discloses a kind of for plant seed neutron irradiation 241 Am- 9 Be source dose distribution irradiation device mainly includes cylindrical shield, transport plate, 241 Am- 9 Be neutron source, spherical shielding layer, rubber stick and sample irradiation area;The neutron source will be accompanied by a large number of 59.5keV, 4.438MeV gamma ray production while spontaneous fission, by wrapping spherical lead layer around neutron source shielding gamma ray, so that the main plant seed radiation effect comes from neutron radiation, while the geometric center of neutron source is the spherical center, set up sample irradiation area, ensure the uniformity of plant seed absorbed dose in each area, and directly given without going through tedious measurement and calculation, with the characteristics of standardization dose distribution, can meet the scientific research needs of most legume plant seed neutron irradiation, and can be applied to other kinds of plant seed irradiation and neutron radiation agricultural production and mutation breeding.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of plant seed irradiation breeding, and particularly relates to a plant seed irradiation device 241 Am- 9 Dose distribution device for Be source neutron irradiation. BACKGROUND

[0002] Radiation refers to the process of matter with mass and energy being emitted from an emission source and continuously propagating outward. With the continuous progress of science and technology, scientists have designed various radiation devices, which can be used for nondestructive testing and irradiation processing in the industrial field, radiation disinfection and sterilization, production of radioactive medical isotopes, and cancer treatment in the medical field, and irradiation mutagenesis breeding to improve crop varieties in the agricultural field.

[0003] The study of the interaction between radiation and living organisms has always been an important direction of scientific research. With the continuous intersection of the fields of life science and nuclear science, the study of the relative biological effect (RBE) produced by ray irradiation has received widespread attention. Based on this, the relative biological effect absorbed dose of the organism is very important, at the same time, the demand for biological irradiation devices which are essential for the study of the relative biological effect is increasing, and is developing towards miniaturization, directionality, quantification and better irradiation uniformity. Therefore, designing a device that can accurately give the relative biological effect absorbed dose of the irradiated organism can promote the development of the fields of biological science, medicine and agriculture, and make contributions to human well-being and social progress.

[0004] In the study of radiation mutagenesis breeding and relative biological effect, neutrons have been increasingly concerned by scientists due to their mutagenic advantages. Neutrons have unique wavelengths and energies, can penetrate biological materials and distinguish isotopes (especially hydrogen and deuterium), and have stronger biological effects and higher radiation mutagenic rates than X-rays and gamma rays at the same dose. Different rays produce different direct or indirect ionization densities when interacting with matter, so even if the sample absorbs the same dose, the relative biological effect is different. To compare the biological effects caused by different rays, researchers introduced a quality factor. The quality factor of neutrons is tens of times that of uncharged particles such as X-rays and gamma rays, and the total biological effect caused by a neutron beam is much greater than that of uncharged particles such as X-rays and gamma rays at the same absorbed dose. In addition, neutrons have very high linear energy transfer (LET), so their relative biological effect (RBE) is very high, and they are widely used in radiation biological breeding and neutron therapy for cancer.

[0005] In the work of radiation breeding, how to select the appropriate radiation dose to make plants produce a variety of excellent variations is the primary problem that radiation breeding workers need to consider. Generally speaking, with the increase of the dose, the variation rate of the seeds treated by radiation will also increase accordingly. However, if the dose is too high, it may inhibit the germination of the seeds, and even if the seeds germinate, there is a certain probability that they will die after germination. After radiation treatment, the dose at which the survival rate of the plants is more than 50% and the sterility rate is less than 30% is considered to be the appropriate irradiation dose, and this dose is also called the semi-lethal dose. Therefore, in the actual work of radiation breeding, finding such an appropriate dose or semi-lethal dose is an aspect that researchers must pay attention to. However, accurate calculation and direct measurement of the dose absorbed by the sample have always been a major challenge in the field of neutron irradiation breeding, and there is currently no exact theoretical formula to predict the neutron absorbed dose of samples at different positions. The commonly used methods for estimating the neutron absorbed dose include Monte Carlo simulation and estimation of the dose equivalent around the neutron source, which not only consumes a lot of manpower and material resources, but also causes certain errors in the accuracy of the calculation. SUMMARY

[0006] The purpose of the present application is to solve the technical problems of long cycle, high cost and poor precision in the estimation of neutron absorbed dose in the process of existing research and application of neutron irradiation of plant seeds, and to provide a device for estimating the neutron absorbed dose of plant seeds 241 Am- 9 A dose distribution device for Am-Be source neutron irradiation.

[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] A device for estimating the neutron absorbed dose of plant seeds 241 Am- 9 A dose distribution device for Am-Be source neutron irradiation, comprising a transport plate and a cylindrical shielding body placed on the transport plate;

[0009] A 241 Am- 9 Be neutron source is arranged at the geometric center position inside the cylindrical shielding body; 241 Am- 9 The outer periphery of the Am-Be neutron source is coated with a spherical shielding body composed of a fixed source shielding body and a detachable shielding limiting body which can be divided into two parts in the horizontal direction, and the spherical shielding body is provided with a spherical sample irradiation area which can be divided into two parts in the horizontal direction, and the spherical sample irradiation area is provided with a small hole channel for the Am-Be neutron source to enter and exit; 241 Am- 9 The inner diameter of the cylindrical shielding body is provided with two movable hemispherical cylinders at the same height as the spherical sample irradiation area, and one end of the movable hemispherical cylinder extends to 241 Am- 9The Be neutron source is connected with the spherical sample irradiation area at one end and extends to the outside of the cylindrical shielding body and is connected with the sample changing handle at the other end. 241 Am- 9 The Be neutron source is connected with the sample changing rod at one end, and the sample changing rod is located at one end of the cylindrical shielding body and is provided with a sample changing handle.

[0010] The spherical sample irradiation area is composed of 241 Am- 9 The geometric center of the Be neutron source is the center of the sphere, and the radii of the plurality of spherical regions increase in turn, and the inner surfaces of the plurality of spherical regions are each provided with a seed sample adhering spherical shell.

[0011] As a further preferred technical solution of the present application, the spherical sample irradiation area is composed of 241 Am- 9 The geometric center of the Be neutron source is the center of the sphere, and the radii of the five spherical regions increase in turn, and the radii of the inner surfaces of the five spherical regions are 2.65 cm, 3.5 cm, 4.35 cm, 5.2 cm and 6.05 cm in turn.

[0012] Further, the sample changing rod is composed of a polyethylene rod, a hard lead layer and a stainless steel rod with an arc-shaped free end connected in turn, and the rubber rod is connected with the arc-shaped end of the stainless steel rod.

[0013] Further, the cylindrical shielding body is composed of the same materials from the inside to the outside and in the same direction as the sample changing rod, and is composed of stainless steel with a diameter of 29.8 cm and a height of 29.8 cm, a hard lead layer with a thickness of 0.1 cm and polyethylene with a thickness of 3 cm in turn.

[0014] Further, the rubber rod is provided with a partition plate on both sides.

[0015] Further, the 241 Am- 9 The Be neutron source is an americium-beryllium alloy cylinder.

[0016] Further, the 241 Am- 9 The Be neutron source has a diameter of 1.5 cm and a height of 0.6 cm.

[0017] Further, the seed sample adhering spherical shell is a hard lead spherical shell with a thickness of 1.5 mm.

[0018] Further, the upper surface of the transportation plate is provided with a groove matched with the bottom of the cylindrical shielding body.

[0019] Further, the bottom of the transportation plate is provided with universal wheels.

[0020] The present application has the following beneficial effects compared with the prior art:

[0021] 1. The present application is used for plant seeds 241 Am- 9 The dose distribution device of Be source neutron irradiation mainly comprises a cylindrical shielding body, a transport plate, 241 Am- 9 a Be neutron source, a spherical shielding layer, a rubber rod and a spherical sample irradiation area, 241 Am- 9 The neutron yield of the Be neutron source is 2.2*10 6 n*s -1 Ci -1 At the same time, a large amount of gamma rays will be generated, and the gamma ray yield is 1.31*10 6 n*s -1 Ci -1 which is very close to the neutron yield, and needs to be shielded. Therefore, a spherical lead layer (spherical shielding body) is wrapped around the neutron source to shield the gamma rays, so that the main contribution to the radiation effect on plant seeds comes from neutron radiation, which meets the requirements of neutron irradiation of plant seeds; at the same time, 241 Am- 9 The Be neutron source is spherical, and five spherical areas with increasing radii are arranged outside the spherical shielding body as spherical sample irradiation areas. The spherical sample irradiation areas make the absorbed dose of plant seeds in each area have good uniformity, and also make the absorbed dose of seeds between the spherical areas have obvious gradient, and fully utilize the limited space resources near the neutron source. In addition, the cylindrical shielding body can reflect part of the neutrons emitted by the neutron source back to the spherical sample irradiation area, fully utilizing the limited neutron yield. Therefore, the present application can irradiate seeds with any neutron absorbed dose in gradient, and the absorbed dose of each gradient seed has good uniformity. This makes the neutron irradiation of plant seeds have the characteristics of standardized dose distribution, which can meet the needs of most scientific researches of legume plant seeds, and also can meet the needs of wheat, corn and other plant seeds, in addition, it can also be used for neutron radiation agricultural production and mutation breeding.

[0022] 2. The material outside the cylindrical shielding body is polyethylene, which is a common light element. The reaction interface between H and neutrons is large, that is, the probability of interaction between H and neutrons such as elastic scattering, inelastic scattering and neutron capture is large, which can absorb and slow down neutrons to play a role in radiation protection. Therefore, materials with high H content are often used in the field of radiation protection. Therefore, the applicant selects polyethylene with high H content as the main material of the cylindrical shielding body for slowing down and absorbing neutrons. The size and 241 Am- 9The design of the installation position of the Be neutron source makes the radiation protection ability reach a safe degree.

[0023] 3、The transport plate of the application has a groove with a radius of 18 cm on the top, which can embed the cylindrical shielding body above to reduce shaking, and the universal wheels on the bottom can make it move flexibly with the cylindrical shielding body, which is convenient to use.

[0024] 4、The raw materials required for the preparation of the application are lead, hard lead, stainless steel and polyethylene, which are cheap, easy to obtain and easy to make, and the price is cheap. 241 Am- 9 The Be neutron source is also easy to obtain. DETAILED DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a structure diagram of the cylindrical shielding body of the application;

[0026] Figure 2 It is a longitudinal section view of Figure 1 ;

[0027] Figure 3 It is a schematic diagram of the side of the transport plate of the application;

[0028] Figure 4 It is a schematic diagram of the cross section of the whole device of the application;

[0029] Figure 5 It is a partial enlarged view of the source moving rod of the application 241 Am- 9 Be neutron source and partial enlarged view of the spherical sample irradiation area;

[0030] Figure 6 It is a partial enlarged view of the source moving rod of the application;

[0031] The meanings of the reference signs are as follows: 1, cylindrical shielding body; 2, sample changing handle; 3, 241 Am- 9Be neutron source; 4, spherical sample irradiation area; 5, movable half-sphere cylinder; 6, detachable shielding limiting body; 7, seed sample attached spherical shell; 8, rubber rod; 9, partition plate; 10, transport plate; 11, universal wheel; 12, source moving handle; 13, fixed source shielding body; 14, stainless steel rod; 15, hard lead layer; 16, polyethylene rod. DETAILED DESCRIPTION

[0032] The application will be further described below in conjunction with the drawings and specific embodiments.

[0033] As Figures 1-6 shown in the drawings, a device for neutron irradiation of plant seeds comprises a cylindrical shielding body 1 and a transport plate 10, the top of the transport plate 10 is provided with a 18cm radius groove for placing the cylindrical shielding body 1, and the bottom of the transport plate 10 is provided with four universal wheels 11 for facilitating movement of the device. 241 Am- 9 The device for dose distribution irradiation of a Be source comprises a cylindrical shielding body 1 and a transport plate 10, the top of the transport plate 10 is provided with a 18cm radius groove for placing the cylindrical shielding body 1, and the bottom of the transport plate 10 is provided with four universal wheels 11 for facilitating movement of the device.

[0034] The cylindrical shielding body 1 has a diameter of 36cm and a height of 36cm, and a Be neutron source 3 is arranged at the geometric center of the inside of the cylindrical shielding body 1. 241 Am- 9 The Be neutron source 3 is arranged at the geometric center of the inside of the cylindrical shielding body 1. 241 Am- 9 The Be neutron source 3 is arranged at the geometric center of the inside of the cylindrical shielding body 1. 241 Am- 9 The Be neutron source 3 is arranged at the geometric center of the inside of the cylindrical shielding body 1. 241 Am- 9 The Be neutron source 3 is arranged at the geometric center of the inside of the cylindrical shielding body 1. 241 Am- 9 The Be neutron source 3 is arranged at the geometric center of the inside of the cylindrical shielding body 1.

[0035] Specifically, 241 Am- 9Be Neutron Source 3 is an americium-beryllium alloy cylinder with a diameter of 1.5 cm and a height of 0.6 cm. It is an isotopic neutron source with a neutron yield of 2.2 × 10⁻⁶. 6 n∙s -1 ∙Ci -1 The half-life is 432.2 years. 241 Am- 9 The Be neutron source has an average neutron energy of 4.5 MeV. During its spontaneous fission, it produces a large amount of gamma rays at 59.5 keV and 4.438 MeV, with a gamma-ray yield of 1.31 × 10⁻⁶. 6 n∙s -1 ∙Ci -1 The irradiation area 4 of the spherical sample is... 241 Am- 9 The Be neutron source 3 has a geometric center of five spherical regions with successively increasing radii. The inner surface radii of the five spherical regions are 2.65cm, 3.5cm, 4.35cm, 5.2cm, and 6.05cm, respectively. The inner surface of the spherical regions is provided with a hard lead seed sample attachment shell 7 with a seed sample attachment thickness of 1.5mm.

[0036] Specifically, the transfer rod is composed of a polyethylene rod 16, a hard lead layer 15, and a stainless steel rod 14 with an arc-shaped free end connected in sequence, and the rubber rod 8 is connected to the arc-shaped end of the stainless steel rod 14.

[0037] Specifically, the cylindrical shield 1 has the same material composition from the inside to the outside as the source transfer rod in the extension direction, consisting of stainless steel with a diameter of 29.8 cm and a height of 29.8 cm, hard lead with a thickness of 0.1 cm, and polyethylene with a thickness of 3 cm.

[0038] Specifically, the rubber rod 8 has 1.5mm thick hard lead partitions 9 on its upper and lower sides.

[0039] Before each irradiation, the spherical sample irradiation area 4 is first pulled out using the sample change handle 2 mounted on the movable hemispherical cylinder 5. Plant seeds are then filled into the five seed sample attached spherical shells 7 through the opening after separation, and the shells are sealed with tape. The samples are then pushed back into the cylindrical shielding body 1 as before. After irradiation, the spherical sample irradiation area 4 is pulled out again, the tape is removed, the sample is removed, and the process is repeated. This process is repeated for the radioactive source (…). 241 Am- 9 When the Be neutron source 3) moves, the source-shifting handle 12 installed on the left side of the device is pulled, which drives the source-shifting rod and rubber rod 8 connected to it, thereby driving the solid source shield 13 connected to the rubber rod 8 to move, thus driving 241 Am- 9 Be neutron source 3 performs the required displacement.

[0040] The neutron absorbed dose rates of the five spherical regions of the spherical sample irradiation area 4 are given by simulation techniques for different types of plant seeds, and the process is as follows: the neutron absorbed dose rates of the five spherical regions of the spherical sample irradiation area 4 are given by simulation techniques for different types of plant seeds, and the process is as follows: the neutron absorbed dose rates of the five spherical regions of the spherical sample irradiation area 4 are given by simulation techniques for different types of plant seeds, and the process is as follows: 241 Am- 9 Based on the model of the Be neutron source, according to the energy spectrum data of neutrons and gamma rays, and the specific release energy factor (Kerma factor) of neutrons and the mass energy absorption coefficient of rays, etc., the simulation and calculation are carried out based on the Monte Carlo method.

[0041] Table 1 is the neutron absorbed dose rate of pea seeds in the five spherical regions of the device when the activity of the radiation source is 10 Ci.

[0042] Table 1 Neutron absorbed dose rate of the five spherical regions

[0043]

[0044] Table 2 is the relative error of the neutron absorbed dose rate of pea seeds in the five spherical regions of the device.

[0045] Table 2 Relative error of the neutron absorbed dose rate of the five spherical regions

[0046]

[0047] A human tissue equivalent point is placed at a distance of 50 cm from the top and side of the device to detect the Monte Carlo simulation of the absorbed dose rate, to simulate the neutron and gamma ray absorbed dose that the human body may receive when the sample is changed, to test the radiation safety. The results show that without placing any irradiation samples, the neutron absorbed dose rates at the top and side of 50 cm are 8.79 μSv / h and 9.95 μSv / h, respectively, and the gamma ray absorbed dose rates are 0.13 μSv / h and 0.14 μSv / h, respectively. According to GB18871-2002 "Ionizing Radiation Protection and Radiation Source Safety Standard", the radiation standard for human safety is: the annual average effective dose (but not any retrospective average) ≤20 mSv for 5 consecutive years; the effective dose in any year ≤50 mSv; the annual equivalent dose of the eye lens ≤150 mSv; the annual equivalent dose of the limbs (hands and feet) or skin ≤500 mSv. Considering the characteristics and use of the device, it can meet the standard during operation, and the use at a safe distance is harmless to human safety.

Claims

1. A plant seed 241 Am- 9 Dose distribution device for Be source neutron irradiation, characterized in that, It comprises a transport plate (10) and a cylindrical shielding body (1) placed on the transport plate (10). The cylindrical shield (1) has a geometric center located inside. 241 Am- 9 Be neutron source (3) 241 Am- 9 The Be neutron source (3) is surrounded by a spherical shield consisting of a solid source shield (13) and a detachable shielding limiter (6) that can be split into two parts in the horizontal direction. The spherical shield has a spherical sample irradiation area (4) that can be split into two parts in the horizontal direction on its outer periphery. The spherical sample irradiation area (4) has a reserved space for a sample to be irradiated. 241 Am- 9 The Be neutron source (3) has a small aperture channel for entry and exit; the cylindrical shield (1) has two movable hemispherical cylinders (5) located at the same height as the spherical sample irradiation area (4) on one radial side, and one end of the movable hemispherical cylinder (5) extends to 241 Am- 9 The Be neutron source (3) is connected to the spherical sample irradiation area (4), and the other end extends to the outside of the cylindrical shield (1) and is connected to the sample change handle (2). The cylindrical shield (1) is provided with a rubber rod (8) on the other side of its inner radial direction, which is connected to the solid source shield (13) and can move freely in the small hole channel of the sample irradiation area (4). The rubber rod (8) is far away from the solid source shield (13). 241 Am- 9 One end of the Be neutron source (3) is connected to one end of the transfer rod, and the transfer rod is located outside the cylindrical shield (1) with a transfer handle (12) at one end. The sample irradiation area (4) is composed of a plurality of spherical regions with their geometric centers as the center of the sphere and their radii increasing in order, and the inner surface of each spherical region is provided with a seed sample adhering spherical shell (7). 241 Am- 9 The geometric center of the Be neutron source (3) is the center of the sphere, and the plurality of spherical regions are composed of spherical regions with increasing radii in order, and the inner surface of each spherical region is provided with a seed sample adhering spherical shell (7).

2. A plant seed according to claim 1 241 Am- 9 Dose distribution device for neutron irradiation in a Be source, characterized in that The spherical sample irradiation area (4) is composed of five spherical areas with geometric centers at the sphere center and radii increasing in order, and the inner surface radii of the five spherical areas are 2.65 cm, 3.5 cm, 4.35 cm, 5.2 cm, and 6.05 cm in order. 241 Am- 9 The Be neutron source (3) is composed of five spherical areas with geometric centers at the sphere center and radii increasing in order, and the inner surface radii of the five spherical areas are 2.65 cm, 3.5 cm, 4.35 cm, 5.2 cm, and 6.05 cm in order.

3. A plant seed according to claim 2 241 Am- 9 Dose distribution device for neutron irradiation in a Be source, characterized in that The movable source rod is composed of a polyethylene rod (16), a hard lead layer (15) and a stainless steel rod (14) with an arc-shaped free end, and the rubber rod (8) is connected with the arc-shaped end of the stainless steel rod (14).

4. A plant seed according to claim 3 241 Am- 9 Dose distribution device for neutron irradiation in a Be source, characterized in that The cylindrical shielding body (1) is composed of the same materials from inside to outside and in the extending direction of the movable source rod, and in sequence, it is composed of stainless steel with a diameter of 29.8 cm and a height of 29.8 cm, a hard lead layer with a thickness of 0.1 cm and a polyethylene layer with a thickness of 3 cm.

5. A plant seed according to claim 3 241 Am- 9 Dose distribution device for neutron irradiation in a Be source, characterized in that The rubber rod (8) is provided with a partition plate (9) on both sides.

6. A plant seed according to claim 1 241 Am- 9 Dose distribution device for neutron irradiation in a Be source, characterized in that The 241 Am- 9 The Be neutron source is a cylinder of an alloy of americium and beryllium.

7. A plant seed according to claim 6 241 Am- 9 Dose distribution device for neutron irradiation in a Be source, characterized in that The 241 Am- 9 The Be neutron source has a diameter of 1.5 cm and a height of 0.6 cm.

8. A plant seed according to any one of claims 1-7 241 Am- 9 Dose distribution device for neutron irradiation in a Be source, characterized in that The seed sample adhering shell (7) is a hard lead shell with a thickness of 1.5 mm.

9. A plant seed according to any one of claims 1-7 241 Am- 9 Dose distribution device for neutron irradiation in a Be source, characterized in that The upper surface of the transport plate (10) is provided with a groove matched with the bottom of the cylindrical shielding body (1).

10. A plant seed according to any one of claims 1-7 241 Am- 9 Dose distribution device for neutron irradiation in a Be source, characterized in that The bottom of the transport plate (10) is provided with universal wheels (11).

Images