A spallation neutron source target for conducting irradiation experiments

Abstract

The present application relates to a spallation neutron source target body capable of carrying out irradiation experiments, wherein a sample target piece (3) is arranged side by side in a heavy metal target piece (2), a hole (31) is opened in the sample target piece (3), a sample container (4) is placed in the hole (31), and the sample to be subjected to the irradiation experiment is placed in the sample cavity of the sample container (4). The spallation neutron source target body not only has the function of generating neutrons, but also irradiates the sample with the large amount of neutrons generated. After irradiation to a set dose, the sample container (4) can be directly taken out to take out the sample for analysis, which will not affect the normal operation and life of the target body. The sample target piece (3) and the heavy metal target piece (2) are arranged side by side, and the neutron flux is high. The irradiation dose received by the sample to be irradiated is much higher than the dose of the sample irradiated by the neutron on-line neutron source spectrometer. The target body can be used to study the irradiation effect of materials.

Description

Technical Field

[0001] The present application relates to the field of nuclear technology, and in particular to a spallation neutron source target body capable of carrying out irradiation experiments. Background Art

[0002] The spallation neutron source is a process where protons are accelerated to very high energies by an accelerator, and then collide with a heavy metal target to produce neutrons through spallation reactions. The heavy metal bombarded by high-energy protons is generally called a target, which is also the source of neutrons. The basic function of the target is to provide heavy metals for high-energy protons to bombard and produce neutrons. The generated neutrons are then extracted to irradiate samples, where they interact with the sample through scattering, and are used to analyze the internal structure and microscopic properties of the sample.

[0003] According to the different types of protons accelerated by the accelerator, they are divided into pulsed spallation neutron sources (i.e. the proton beam is pulsed, has a certain frequency, and the neutrons generated are also pulsed) and continuous spallation neutron sources. The China Spallation Neutron Source belongs to the pulsed spallation neutron source. At present, the targets of all pulsed spallation neutron sources in the world (including the US SNS, Japan JPARC, and the UK ISIS) only have the function of generating neutrons. There is no space for placing irradiation experimental samples, that is, there is no function of irradiating samples in the target body. Only the Swiss SINQ continuous spallation neutron source has the function of sample irradiation in its target body, but its irradiated samples are placed in the sealed target container of the target body. If you want to take out the samples, you must disassemble the target container after the target body has been used to the design life, and then you can take out the irradiated samples. The target body cannot be used after the samples are taken out.

[0004] The applicant submitted an invention patent application entitled "A Spallation Neutron Source Target" (application publication number CN 103594137 A) on November 5, 2013. The spallation neutron source target includes a target container and a target piece, but the target piece only has the function of generating neutrons. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a spallation neutron source target body for carrying out irradiation experiments, which can place and take out irradiated samples without replacing the target body.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: a spallation neutron source target body capable of carrying out irradiation experiments, comprising a target container (1), a heavy metal target piece (2) and a sample target piece (3); the target container (1) comprises a slot body (11) and a cover body (12) mounted on the opening of the slot body (11); the slot body (11) defines a target piece installation cavity (13); a gap (14) is provided at a position where the cover body (12) and the sample target piece (3) face each other; the heavy metal target piece (2) and the sample target piece (3) are arranged side by side in the target piece installation cavity (13); the sample target piece (3) has a hole (31) opening toward the cover body (12); a sample container (4) is placed in the hole (31); and a sample to be subjected to irradiation experiments is placed in the sample container (4).

[0007] In a specific embodiment of the present invention, the material of the heavy metal target piece (2) is tungsten, tantalum, gold, uranium or lead, the material of the target container (1) is stainless steel, and the material of the sample target piece (3) is stainless steel.

[0008] In a specific embodiment of the present invention, the number of heavy metal target sheets (2) and sample target sheets (3) is one or more. For example, the number of heavy metal target sheets (2) and sample target sheets (3) is two, three, four, five or more. Preferably, the number of heavy metal target sheets (2) is greater than the number of sample target sheets (3). For example, the number of heavy metal target sheets (2) is 13, and the number of sample target sheets (3) is 3. Preferably, each sample target sheet (3) is separated by at least one heavy metal target sheet (2), that is, the sample target sheets (3) are not arranged side by side in the target sheet installation cavity (13) in a close proximity, while the heavy metal target sheets (2) can be arranged side by side in the target sheet installation cavity (13) in a close proximity.

[0009] In a specific embodiment of the present invention, the number of holes (31) is one or more. For example, the number of holes (31) is one, two, three, four, five, six, seven, eight, nine or ten. Correspondingly, the number of sample containers (4) is one or more. For example, the number of sample containers (4) is one, two, three, four, five, six, seven, eight, nine or ten.

[0010] In a specific embodiment of the present invention, the sample container (4) has a sample cavity (41) for accommodating a sample to be subjected to an irradiation experiment.

[0011] In a specific embodiment of the present invention, the target container (1) is a single-layer structure, a target window (5) is provided at the front end of the target container (1), a coolant inlet (6) and a coolant outlet (7) are provided at the rear end, and a coolant flow gap is provided between every two adjacent target plates (heavy metal target plates (2) and / or sample target plates (3)) in the target plate installation cavity (13). Preferably, the coolant inlet (6) and the coolant outlet (7) are respectively arranged on both sides of the target plate. Preferably, at least a convex rib (9) is provided at the bottom of the target plate installation cavity (13), and the convex rib (9) is used to separate two adjacent target plates to form a coolant flow gap.

[0012] In a specific embodiment of the present invention, a coolant flow channel (8) is provided at the top and / or bottom of the target piece mounting cavity (13), and the coolant flow channel (8) is located at the front of the target piece mounting cavity (13), and is located between two adjacent coolant flow gaps, and is directly opposite to the top and / or bottom of the corresponding target piece.

[0013] In a specific embodiment of the present invention, the thickness of the heavy metal target piece (2) gradually increases from the front end to the rear end of the target container (1). The front end herein refers to the end facing the neutron source.

[0014] In a specific embodiment of the present invention, the trough body (11) and the cover body (12) are sealed by electron beam welding, and the sample target piece (3) and the cover body (12) are sealed by electron beam welding.

[0015] In a specific embodiment of the present invention, a thermocouple (10) is provided on the target sheet located in front of the target sheet installation cavity (13), the thermocouple (10) passes through the target sheet installation cavity (13) and is connected to the heavy metal target sheet (2) and / or the sample target sheet (3), and the thermocouple (10) is sealed and matched with the target sheet installation cavity (13).

[0016] Beneficial Effects of the Invention

[0017] The spallation neutron source target body capable of carrying out irradiation experiments of the present invention is based on the invention patent application entitled "A Spallation Neutron Source Target" previously filed by the applicant, wherein a sample target sheet is interspersed in a heavy metal target sheet, a hole is opened in the sample target sheet, a sample container is placed in the hole, and the sample to be irradiated is placed in the sample cavity of the sample container. The spallation neutron source target body capable of carrying out irradiation experiments of the present invention is not only a component of the spallation neutron source for generating neutrons, but also can use the target body to carry out sample irradiation damage experiments. By opening a certain space in the target body (in the sample cavity of the sample container) to place the experimental sample, the target body generates a large number of neutrons while irradiating the sample. After irradiation to the set dose, the sample container can be directly taken out to take out the sample, so as to analyze the various properties of the sample after irradiation and study the irradiation effect of irradiation on the sample. Since the sample container can be directly taken out by a manipulator, it is not necessary to destroy the target container, and the normal operation and life of the target body will not be affected.

[0018] The function of a general spallation neutron source target is only to receive proton bombardment to generate neutrons, which are then drawn out to irradiate samples, and the neutrons interact with the samples to analyze the internal structure and microscopic properties of the samples. The spallation neutron source target of the present invention, in addition to the basic function of generating neutrons, can also place samples in the target for irradiation experiments, and has the function of irradiating samples. Moreover, the irradiation dose of the samples in the target is much higher than that at the spectrometer, which shortens the irradiation experiment and improves efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A perspective view of a spallation neutron source target body capable of carrying out irradiation experiments provided by an embodiment of the present invention;

[0020] Figure 2 Display a stereoscopic image of a sample target;

[0021] Figure 3 Display a top view of the sample target;

[0022] Figure 4 The sample cavity and the sample cavity cover of the sample container are shown, wherein the left sub-figure shows the state when no sample is placed in the sample cavity, and the right sub-figure schematically shows the state when a sample is placed in the sample cavity;

[0023] Figure 5 Displays the status of the sample container when the sample chamber cover covers the sample chamber;

[0024] Figure 6 Top and side views of the target container are shown, showing the coolant flow paths. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings. The elements and features described in one drawing or one embodiment of the present invention may be combined with the elements and features shown in one or more other drawings or embodiments. It should be noted that for the purpose of clarity, components that are not related to the present invention and are known to those of ordinary skill in the art are omitted from the drawings and descriptions of the present invention.

[0026] Figure 1 A perspective view of a spallation neutron source target body for irradiation experiments provided by an embodiment of the present invention. Figure 1As shown, the spallation neutron source target body includes a target container 1 of a single-layer structure, a plurality of heavy metal target pieces 2 and a plurality of sample target pieces 3. The target container 1 includes a trough body 11 and a cover body 12 covered at the opening of the trough body, and the trough body 11 defines a target piece installation cavity 13. A gap 14 is provided at a position where the cover body 12 is directly opposite to the sample target piece 3. The plurality of heavy metal target pieces 2 and the plurality of sample target pieces 3 are arranged side by side in the target piece installation cavity 13. The plurality of sample target pieces 3 have holes 31 opening toward the cover body 11, and a sample container 4 is placed in the hole 31, and a sample to be subjected to an irradiation experiment is placed in the sample container 4.

[0027] The material of the heavy metal target 2 can be tungsten, tantalum, gold, uranium or lead. Figure 1 The heavy metal target piece 2 shown in the figure is made of tungsten. The target container 1 and the sample target piece 3 are made of stainless steel, such as 316L stainless steel. The target container 1 and the sample target piece 3 are made of stainless steel, and the sample target piece 3 can be electron beam welded to the target container 1 to ensure that the coolant does not leak out of the target container 1. Although the material of the sample target piece 3 can also be tungsten, which also has the function of generating neutrons, it cannot be directly electron beam welded to the target container 1 if tungsten is used.

[0028] The number of the heavy metal target pieces 2 and the number of the sample target pieces 3 are respectively one or more, and the number of the heavy metal target pieces 2 is preferably greater than the number of the sample target pieces 3 . Figure 1 Thirteen heavy metal target pieces 2 and three sample target pieces 3 are shown as examples.

[0029] The sample target 3 can be placed in the front, middle or rear of the target installation cavity 13. Generally speaking, the neutron flux of the front end of the target body is the highest, so the sample target 3 is preferably placed in the front of the target installation cavity 13.

[0030] like Figure 1 As shown, each sample target sheet 3 is separated by at least one heavy metal target sheet 2, that is, the sample target sheets 3 are not arranged side by side in the target sheet installation cavity 13, while the heavy metal target sheets 2 can be arranged side by side in the target sheet installation cavity 13. The shapes of the heavy metal target sheets 2 and the sample target sheets 3 are determined according to the shape of the target sheet installation cavity 13. Figure 1 The target heavy metal target piece 2 and the sample target piece 3 are exemplarily shown in the figure as being in the shape of a rectangle.

[0031] The number of the holes 31 in the sample target sheet 3 is one or more, and accordingly, the number of the sample containers 4 is one or more. Figure 2 and Figure 3 FIG. 4 shows eight holes 31 by way of example, and accordingly, the number of sample containers 4 is eight.

[0032] like Figure 4 As shown, the sample container 4 includes a sample cavity 41 and a sample cavity cover 42 for accommodating a sample to be subjected to an irradiation experiment. Figure 1 As shown, the slit 14 opened at the position where the cover 12 faces the sample target sheet 3 is used to place and take out the sample container 4 , that is, the sample container 4 is placed in the sample target sheet 3 or taken out from the sample target sheet 3 through the slit 14 . Figure 5 Displays the status of the sample container when the sample chamber cover is covering the sample chamber.

[0033] The samples to be irradiated may be, for example, mechanical properties samples or morphological observation samples (such as microstructure observation samples). The size of these samples is generally small, for example, the size of the mechanical properties sample may be 16 mm long, 4 mm wide, and 0.75 mm thick. Since the irradiation space of the sample chamber 41 is limited, in order to place as many samples as possible, the internal layout of the sample chamber 41 should be optimized. Figure 4 The right small picture schematically shows the sample chamber 41 after the sample is placed.

[0034] It should be noted that there are no specific requirements for the sizes of the target container 1, the heavy metal target piece 2, the sample target piece 3 and the sample container 4. However, on the one hand, they are required to be designed according to the size of the sample to be irradiated, and on the other hand, the thickness of the sample target piece 3 is required to be as small as possible to avoid affecting the efficiency of the target body in generating neutrons.

[0035] See also Figure 1 , a target window 5 is provided at the front end of the target container 1. Moreover, since a large amount of heat is generated when high-energy protons bombard the heavy metal target 2, the heavy metal target 2 needs to be cooled, so a coolant inlet 6 and a coolant outlet 7 are provided at the rear end of the target container 1, and a coolant flow gap is provided between every two adjacent target plates (heavy metal target plates 2 and / or sample target plates 3) in the target plate installation cavity 13. A cooling method of forming a parallel flow of coolant between the heavy metal target plates 2 and / or the sample target plates 3 through the coolant flow gap is used to optimize the cooling performance. Since the heat generated by the first few heavy metal target plates 2 located at the front end of the target plate installation cavity 13 is relatively large, thermocouples 10 are provided on these heavy metal target plates 2, and the temperatures of the heavy metal target plates 2 are monitored by the thermocouples 10. The target container 1 includes a slot body 11 and a cover body 12 installed at the opening of the slot body 1. The trough body 11 is fastened around the cover body 12 and then sealed by electron beam welding, and the upper end of the sample target piece 3 is matched with the cover body 12 and then electron beam welding is performed to ensure the sealing of the target container 1. The thermocouple 10 passes through the cover body 12 and is connected to the heavy metal target piece 2, and the thermocouple 10 and the cover body 12 are sealed to prevent the coolant from leaking from the connection between the thermocouple 10 and the cover body 12.

[0036] The spallation neutron source target provided by the embodiment of the present invention has a single-layer structure, and a cooling circuit is formed in the target piece installation cavity 13 through the coolant inlet 6 and the coolant outlet 7, which has a simple structure and is easy to process.

[0037] In order to reduce the processing difficulty of the spallation neutron source target body while meeting the conditions of engineering application, the target window 4 adopts a structure that is concave toward the target piece installation cavity 13, with a cylindrical surface in the middle and spherical surfaces at both ends. Those skilled in the art can understand that the cylindrical surface and spherical surface referred to here are only parts of the complete cylindrical surface and the complete spherical surface.

[0038] In order to improve the efficiency of generating neutrons, the thickness of the plurality of heavy metal target pieces 2 arranged side by side gradually increases from the front end to the rear end of the target container 1, that is, the thickness of the rear one of every two adjacent heavy metal target pieces 2 is greater than the thickness of the front one. The front end in this article refers to the end facing the neutron source.

[0039] See also Figure 6 Since the heat generated by the first few heavy metal target pieces 2 is relatively large, a coolant flow channel 8 is provided at the top and / or bottom of the target piece installation cavity 13, and the coolant flow channel 8 is located at the front end of the target piece installation cavity 13, so that the heavy metal target piece 2 located at the front end can contact with more coolant, thereby improving the heat dissipation capacity of the heavy metal target piece 2. Specifically, the coolant flow channel 8 is arranged opposite to the corresponding heavy metal target piece 2, that is, the coolant flow channel 8 is opposite to the top and / or bottom of the heavy metal target piece 2.

[0040] The coolant inlet 6 and the coolant outlet 7 are disposed on both sides of the heavy metal target 2 and / or the sample target 3. The coolant flows from one side of the heavy metal target 2 and / or the sample target 3 to the other side of the heavy metal target 2 and / or the sample target 3 through the coolant flow gap, and cools the heavy metal target 2 and / or the sample target 3 when flowing through the coolant flow gap. Figure 6 At least the bottom of the target plate installation cavity 13 is provided with a convex rib 9, and the convex rib 9 is used to separate two adjacent heavy metal target plates 2 and / or sample target plates 3 to form a coolant flow gap.

[0041] When conducting a sample irradiation experiment, the sample to be irradiated is marked according to the pre-designed sample container 4 and placed in the sample cavity 41, and then the sample cavity cover 42 is covered. The target is moved to a hot chamber for maintaining the target, and the sample container 4 is placed in the hot chamber. The sample container 4 is inserted into the hole 31 of the sample target sheet 3 of the target through the gap 14 by a remote control manipulator, and then the target is moved to the working position. The heavy metal target sheet 2 is irradiated by protons to produce neutrons, and the sample in the sample target sheet 3 is irradiated by neutrons. After a certain dose of neutron irradiation is accumulated (generally determined by calculation), the target is moved to the hot chamber, the sample container 4 is taken out by the remote control manipulator, and a new sample container 4 is replaced. The target continues to move to the working position to work, and a cycle ends. Because the sample has been activated after irradiation and has a high radioactivity, it needs to be cooled for a period of time after taking out the sample container 4. After the dose is reduced to a certain level, the sample cavity cover 42 is disassembled by the manipulator, and the irradiated sample is taken out from the sample cavity 41 for post-irradiation analysis.

[0042] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. A person skilled in the art of the present invention may also make several simple deductions, modifications or substitutions based on the concept of the present invention. These deductions, modifications or substitutions also fall within the scope of the claims of the present invention.

Claims

1. A spallation neutron source target body capable of carrying out irradiation experiments, comprising a target container (1), a heavy metal target piece (2) and a sample target piece (3); the target container (1) comprises a trough body (11) and a cover body (12) mounted on an opening of the trough body (11); the trough body (11) defines a target piece installation cavity (13); a gap (14) is formed at a position where the cover body (12) and the sample target piece (3) are directly opposite each other; the heavy metal target piece (2) and the sample target piece (3) are arranged side by side in the target piece installation cavity (13); the sample target piece (3) has a hole (31) opening toward the cover body (12); a sample container (4) is placed in the hole (31); and a sample to be subjected to irradiation experiments is placed in the sample container (4).

2. The spallation neutron source target according to claim 1, characterized in that: The material of the target container (1) is stainless steel, the material of the heavy metal target piece (2) is tungsten, tantalum, gold, uranium or lead, and the material of the sample target piece (3) is stainless steel.

3. The spallation neutron source target according to claim 1, characterized in that: The number of the heavy metal target pieces (2) and the number of the sample target pieces (3) are respectively one or more, and the number of the holes (31) are one or more.

4. The spallation neutron source target according to claim 1, characterized in that: The sample container (4) has a sample cavity (41) for accommodating a sample to be subjected to an irradiation experiment.

5. The spallation neutron source target according to any one of claims 1 to 4, characterized in that: The target container (1) is a single-layer structure, a target window (5) is arranged at the front end of the target container (1), a coolant inlet (6) and a coolant outlet (7) are arranged at the rear end, and a coolant flow gap is provided between every two adjacent target pieces in the target piece installation cavity (13).

6. The spallation neutron source target according to claim 5, characterized in that: At least the bottom of the target piece installation cavity (13) is provided with a convex rib (9), and the convex rib (9) is used to separate two adjacent target pieces to form the coolant flow gap.

7. The spallation neutron source target according to claim 5, characterized in that: A coolant flow channel (8) is provided at the top and / or bottom of the target piece installation cavity (13); the coolant flow channel (8) is located at the front of the target piece installation cavity (13), and is located between two adjacent coolant flow gaps, and is directly opposite to the top and / or bottom of the corresponding target piece.

8. The spallation neutron source target according to any one of claims 1 to 4, characterized in that: From the front end to the rear end of the target container (1), the thickness of the heavy metal target piece (2) gradually increases.

9. The spallation neutron source target according to any one of claims 1 to 4, characterized in that: The trough body (11) and the cover body (12) are sealed by electron beam welding, and the sample target piece (3) and the cover body (12) are sealed by electron beam welding.

10. The spallation neutron source target according to any one of claims 1 to 4, characterized in that: A thermocouple (10) is provided on the target sheet located in front of the target sheet installation cavity (13); the thermocouple (10) passes through the target sheet installation cavity (13) and is inserted into the heavy metal target sheet (2) and / or the sample target sheet (3); and the thermocouple (10) is sealed and matched with the target sheet installation cavity (13).

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