Fusion Reactor Irradiation Sample Injector

Abstract

The present invention belongs to the technical field of fusion reactors, and specifically discloses a fusion reactor irradiation sample injector, which comprises a shell I, a gear plate, a reciprocating shaft, a sliding bearing I and a sliding bearing II installed inside the shell I, a shell II, a sample plate installed inside the shell II, a rotating shaft, and a flange I; the shell I is connected to the shell II through the flange I; the rotating shaft is installed in the rotating bearing I located in the shell II and the rotating bearing II located in the shell I; the reciprocating shaft is slidably connected with the sliding bearing I and the sliding bearing II; a rack is provided on the reciprocating shaft, and the rack on the reciprocating shaft is meshed with the gear plate; the gear plate and the sample plate are installed on the rotating shaft; and at least one sample compartment is provided on the sample plate. The fusion reactor irradiation sample injector has the advantages of simple structure, high-efficiency transmission, flexible selection of samples to be tested, reliable sealing performance, reliable containment function, and meeting tritium compatibility requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of fusion reactors, and in particular relates to an irradiation sample injector for a fusion reactor. Background Art

[0002] Using fusion reaction to generate electricity is one of the main directions for the world's scientific community to solve the energy problem of mankind. In order to accelerate the research and development process of fusion energy development and utilization, the International Thermonuclear Experimental Reactor (ITER) project was born, and China is one of the main participating countries. The neutrons produced in the fusion reactor are the key factors for producing tritium and achieving the self-sustaining tritium of the reactor, so it is necessary to measure the neutrons of the fusion reactor. Neutron activation analysis is a highly sensitive trace element analysis method that uses neutrons to react with samples to activate the samples, and measures the radioactivity of the samples after irradiation for quantitative analysis.

[0003] The neutron measurement system needs to send the irradiated samples from the remote end into the blanket of the fusion reactor for irradiation, recover the irradiated samples after irradiation, and measure the irradiated samples. In the process of sending the samples from the remote end to the blanket, the samples need to pass through different equipment and pipelines, which are located in different rooms and buildings. In order to realize the storage and delivery of samples, the irradiated sample injector is one of the key equipment of the neutron measurement system. The irradiated sample injector must not only meet the functions of pre-loading, storage and injection of the samples to be tested, but also have reliable sealing to meet the requirements of radioactive material containment and harmful material containment. In addition, the gas atmosphere of the neutron measurement system contains a certain concentration of tritium, and the irradiated sample injector should also meet the requirements of tritium compatibility.

[0004] Chinese patent CN201710709382.9 discloses a sample injector for irradiated samples entering the reactor. The device drives the sample loading platform to rotate through a motor. After the sample loading chamber is aligned with the sample delivery tube head, the cylinder is driven to move the rubber sleeve up and down, respectively, and closely fit with the bottom and top of the sample loading chamber. Then, compressed gas is introduced. Driven by the compressed gas, the sample enters the system from the sample loading chamber. The injector is not equipped with a sealing structure. The entire sample loading platform is exposed to the environment, and the sample delivery tube head is also directly connected to the environment, which cannot prevent the leakage of radioactive substances and harmful substances into the environment; and the sleeve mechanism has a complex structure, which increases the difficulty of manufacturing, assembly and maintenance, and increases the probability of failure; the material selection of the components cannot be all metal, and it is difficult to meet the requirements of tritium compatibility, so it is not suitable for irradiated sample injection in the neutron measurement system of the fusion reactor.

[0005] Chinese patent CN201710709380.X discloses an automatic sample injection device for neutron activation. The sample injector mentioned in the device consists of a horizontally placed cylinder, a piston and a sample injection tube. Multiple samples are pre-stored in the sample storage tube and are vertically connected to the sample injection tube up and down. During injection, the cylinder pushes the piston to push the sample box into the outlet end of the sample injection tube, and at the same time opens the valve on the air path to allow compressed air to enter and output the sample. The device uses a piston to push the sample into the sample injection tube. The piston and the sample injection tube are connected by sliding, which cannot guarantee effective sealing performance and is difficult to meet the containment function of the fusion reactor neutron measurement system for radioactive substances and harmful substances; and the input of the sample can only be carried out in the order of the samples pre-placed in the sample storage tube, and it is impossible to flexibly select any sample for input, and the operation flexibility is low. Therefore, it is not suitable for irradiation sample injection in the fusion reactor neutron measurement system.

[0006] In view of the problems existing in the prior art, the present invention solves the above problems in a targeted manner. Summary of the invention

[0007] The technical problems to be solved by the present invention are the problems in the prior art such as complex structure, low sample transmission efficiency, inability to flexibly select samples to be tested for injection, difficulty in achieving reliable sealing, inability to meet the requirements for radioactive material containment and harmful material containment, and inability to meet tritium compatibility. A fusion reactor irradiation sample injector is provided, which has the advantages of simple structure, efficient transmission, flexible selection of samples to be tested, reliable sealing performance, reliable containment function, and meeting tritium compatibility requirements.

[0008] To solve the above problems, the technical solution adopted by the present invention is:

[0009] A fusion reactor irradiation sample injector, the injector comprises a shell I, a gear plate, a reciprocating shaft, a sliding bearing I and a sliding bearing II installed inside the shell I, a shell II, a sample plate installed inside the shell II, a rotating shaft, and a flange I; the shell I is connected with the shell II through the flange I; the rotating shaft is installed in the rotating bearing I located in the shell II and the rotating bearing II located in the shell I; the reciprocating shaft is slidably connected with the sliding bearing I and the sliding bearing II; a rack is provided on the reciprocating shaft, and the rack on the reciprocating shaft is meshed with the gear plate; the gear plate and the sample plate are installed on the rotating shaft; and at least one sample chamber is provided on the sample plate.

[0010] The sample bins are evenly distributed on the sample tray, the axis lines of the sample bins are parallel to the axis line of the sample tray, and the distances from the axis line of each sample bin to the axis line of the sample tray are equal.

[0011] A connecting pipe III is installed on the outer surface of the cylinder of the shell II, and the connecting pipe III is connected with the interior of the shell II; the axis of the connecting pipe III is located on the radial line of the shell II.

[0012] The top of the shell II is equipped with flange II and flange III; the connecting pipe I is fixedly connected to the shell II through flange II, and the sensor I is installed on the connecting pipe I; the connecting pipe II is fixedly connected to the shell II through flange III, and the sensor II is installed on the connecting pipe II; the positioner I and the positioner III are installed on the inner upper surface of the shell II.

[0013] The axis center line of the reciprocating shaft is perpendicular to the axis center line of the gear plate; one end of the reciprocating shaft passes through the flange IV and the bellows and is connected to the reciprocating drive mechanism; the flange IV is fixedly connected to the housing I, one end of the bellows is fixedly connected to the flange IV, and the other end of the bellows is fixedly connected to the reciprocating shaft.

[0014] The connecting pipe III is connected to both the gas connecting pipe I and the gas connecting pipe II.

[0015] The sample bin on the sample tray is provided with a groove II at the top position, a buffer pad is provided at the bottom of the sample bin, a channel II is provided at the bottom center position of the sample bin, and a channel I is provided along the radial direction of the sample tray; the axis of the channel I is perpendicular to the axis of the channel II, one end of the channel I passes through the outer circumferential surface of the sample tray, and the other end is connected with the channel II, and the top of the channel II is connected with the sample bin; the outer circumferential surface of the sample tray is provided with grooves I, and the grooves I are respectively located on the upper and lower sides of the channel I; the upper surface of the sample tray is installed with positioners II equal to the number of sample bins, and the positioners II are located on the plane formed by the axis of the sample bin and the axis of the sample tray.

[0016] A sealing ring I is installed in a groove I on the outer peripheral surface of the sample plate, and the sealing ring I is slidably connected to the inner peripheral surface of the shell II.

[0017] A sealing ring II is installed in the groove II on the top of the sample bin, and the sealing ring II is slidably connected to the inner upper surface of the shell II.

[0018] The shell I is in the shape of a cube or a cuboid, the shell II is in the shape of a cylinder; and the sample tray is in the shape of a cylinder.

[0019] The beneficial technical effect of the present invention is that: the fusion reactor irradiation sample injector of the present invention can realize the efficient injection of irradiation samples of the fusion reactor neutron activation analysis system, and can flexibly select different types of samples to be tested pre-installed in the sample tray. All parts are located inside the metal shell and the sealing form of the connection with the outside world is static sealing, which can achieve reliable and efficient sealing and meet the containment function of radioactive substances and harmful substances. The parts are all made of metal materials and meet the requirements of tritium compatibility. It can be used in reactor neutron measurement systems and fusion reactor neutron measurement systems, and has achieved good technical effects. The fusion reactor irradiation sample injector of the present invention mainly comprises a shell and a sample plate, a rotating shaft, a reciprocating shaft and a gear plate installed therein, the rotating shaft is installed in a rotating bearing, the gear plate and the sample plate are fixedly installed on the rotating shaft, the reciprocating shaft is installed in a sliding bearing, and a rack is processed on the reciprocating shaft to be matched and connected with the gear plate, and one end of the reciprocating shaft is connected to a reciprocating driving mechanism. The irradiation sample injector of the present invention effectively solves the problems of complex structure, low transmission efficiency, difficult sealing, inability to meet the functions of radioactive material containment and harmful material containment, inability to meet tritium compatibility, etc. of the existing neutron activation analysis system. The irradiation sample injector can be used in the fusion reactor neutron activation analysis system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a schematic diagram of the overall structure of the fusion reactor irradiation sample injector according to the present invention.

[0021] Figure 2 The figure is a top view of the fusion reactor irradiation sample injector according to the present invention.

[0022] Figure 3 for Figure 1 AA section view.

[0023] Figure 4 Schematic diagram of the structure of the sample tray.

[0024] Figure 5 This is the BB section view of the sample plate.

[0025] In the figure, 1 is a shell I; 2 is a flange I; 3 is a shell II; 4 is a sealing ring I; 5 is a buffer pad; 6 is a sealing ring II; 7 is a flange II; 8 is a sensor I; 9 is a pipe I; 10 is an irradiated sample; 11 is a positioner I; 12 is a positioner II; 13 is a rotating bearing I; 14 is a rotating shaft; 15 is a sample plate; 16 is a positioner III; 17 is a pipe II; 18 is a sensor II; 19 is a flange III; 20 is a pipe III; 21 is a reciprocating shaft; 22 is a rotating bearing II; 23 is a gear plate; 24 is a reciprocating drive mechanism; 25 is a sliding bearing I; 26 is a sliding bearing II; 27 is a flange IV; 28 is a bellows; 29 is a groove I; 30 is a channel I; 31 is a channel II; 32 is a groove II; 33 is a sample chamber; 34 is a gas pipe I; 35 is a gas pipe II. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0027] [Example 1]

[0028] like Figure 1 The fusion reactor irradiation sample injector shown is connected by a housing I1 and a housing II3 through a flange I2, and a sample plate 15, a rotating shaft 14, a reciprocating shaft 21, and a gear plate 23 are installed inside the housing. The rotating shaft 14 is installed in a rotating bearing I13 located in the housing II3 and a rotating bearing II22 located in the housing I1. The sample plate 15 is fixedly installed in the part of the rotating shaft 14 located above the housing II3, and the gear plate 23 is fixedly installed in the part of the rotating shaft 14 located below the housing I1. The axis lines of the housing II3, the rotating bearing I13, the rotating shaft 14, the gear plate 23, and the rotating bearing II22 coincide.

[0029] The outer shape of the shell I1 is a cube or a cuboid, and the outer shape of the shell II3 is a cylinder.

[0030] like Figure 1 and Figure 5 As shown, a pipe III20 is installed on the outer surface of the shell II3 cylinder, and the pipe III20 is connected to the internal space of the shell II3, and the opening of the pipe III20 is smaller than the distance between the upper and lower grooves I29. The positional relationship is that the axis of the pipe III20 is located on the radial line of the shell II3, and the distance from the axis of the pipe III20 to the end face of the flange I2 is equal to the distance from the axis of the channel I30 to the end face of the flange I2.

[0031] like Figure 1 ,as well as Figure 2As shown in the top view of the fusion reactor irradiation sample injector. At least two flanges, flange II7 and flange III19, are installed on the top of the shell II3. The axis lines of flange II7 and flange III19 are parallel to the axis line of the shell II3, and the distances to the axis line of the shell II3 are equal. At the same time, the distances from the axis lines of flange II7 and flange III19 to the axis line of the shell II3 are equal to the distances from the axis line of the sample chamber 33 to the axis line of the sample tray 15. The connecting pipe I9 is ​​fixedly connected to the shell II3 through flange II7, and a sensor I8 is installed on the connecting pipe I9. The connecting pipe II17 is fixedly connected to the shell II3 through flange III19, and a sensor II18 is installed on the connecting pipe II17.

[0032] Positioners I11 and III16 are installed on the inner upper surface of the housing II3. The number of positioners I11 is equal to the number of flanges II7, and the number of positioners III16 is equal to the number of flanges III19. The distances from positioners I11 and III16 to the axis of the housing II3 are equal to the distance from positioner II12 to the axis of the sample tray 15.

[0033] like Figure 3 Shown Figure 1 In the AA cross-sectional view, the reciprocating shaft 21 is installed inside the housing I1, the axis of the reciprocating shaft 21 is perpendicular to the axis of the gear plate 23, the reciprocating shaft 21 is installed in the sliding bearing I25 and the sliding bearing II26, and a rack is machined on the reciprocating shaft 21, and the rack is meshed with the gear plate 23. One end of the reciprocating shaft 21 passes through the flange IV27 and the bellows 28, and then is connected to the reciprocating drive mechanism 24. The flange IV27 is fixedly connected to the housing I1, one end of the bellows 28 is fixedly connected to the flange IV27, and the other end of the bellows 28 is fixedly connected to the reciprocating shaft 21.

[0034] like Figure 4 is a schematic diagram of the sample tray structure, and Figure 5It is a BB cross-sectional view of the sample disk. The sample disk 15 is cylindrical in shape, and at least one sample bin 33 is processed on the upper part of the sample disk 15, and the sample bins 33 are evenly distributed on the sample disk 15 at equal angles along the circumferential direction. The axis of each sample bin 33 is parallel to the axis of the sample disk 15 and is equidistant from the axis of the sample disk 15. A circular groove II32 is processed on the top of each sample bin 33, and the diameter of the groove II32 is larger than the diameter of the sample bin 33. A buffer pad 5 is installed at the bottom of the sample bin 33. A hole II31 is processed at the center position of the bottom of the sample bin 33, and the axis of the hole II31 coincides with the axis of the sample bin 33. A hole I30 is processed along the radial direction of the sample disk 15, and the axis of the hole I30 is perpendicular to the axis of the hole II31. One end of the hole I30 passes through the outer peripheral surface of the sample disk 15, and the other end is connected to the hole II31. The upper surface of the sample tray 15 is provided with positioners II12 equal in number to the sample chamber 33, and the positioners II12 are located on the plane formed by the axis of the sample chamber 33 and the axis of the sample tray 15, and the distances between the positioners II12 and the axis of the sample tray 15 are equal. Grooves I29 are machined on the outer peripheral surface of the sample tray 15, and the grooves I29 are respectively located on the upper and lower sides of the channel I30.

[0035] A sealing ring I4 is installed in the groove I29 on the outer peripheral surface of the sample tray 15, and the sealing ring I4 is slidably connected to the inner peripheral surface of the housing II3. A sealing ring II6 is installed in the groove II32 on the top of the sample compartment 33, and the sealing ring II6 is slidably connected to the inner upper surface of the housing II3.

[0036] The housing, flange, connecting pipe, sample plate 15, rotating shaft 14, reciprocating shaft 21 and gear plate 23 are made of stainless steel.

[0037] The sealing ring I4 and the sealing ring II6 are made of metal.

[0038] The connecting pipe III20 is connected to the gas connecting pipe I34 and the gas connecting pipe II35 respectively, and valves are installed between the connecting pipe III20 and the gas connecting pipe I34 and between the connecting pipe III20 and the gas connecting pipe II35.

[0039] The workflow of the present invention is divided into two steps: irradiation sample preloading and irradiation sample injection. Select pipe I9 as the preloading port, pipe II17 as the injection port; gas pipe I34 is connected to the low-pressure gas tank, and gas pipe II35 is connected to the high-pressure gas tank.

[0040] a) Irradiation sample preloading operation: The reciprocating drive mechanism 24 drives the reciprocating shaft 21 to reciprocate, and the rack on the reciprocating shaft 21 drives the gear plate 23 to rotate. The gear plate 23 is fixedly connected to the rotating shaft 14 and the sample plate 15, and the rotation of the gear plate 23 drives the sample plate 15 to rotate inside the housing II3. The sample chamber 33 on the sample plate 15 is aligned with the irradiation sample preloading port pipe I9 through the positioner I11 and the positioner II12. The irradiated sample 10 is placed in the pipe I9, and the irradiated sample 10 enters the sample chamber 33 under the action of gravity. Whether the irradiated sample 10 enters the sample chamber 33 is monitored by the sensor I8 on the pipe I9. When one sample chamber is filled, the reciprocating shaft 21 is driven again to rotate the sample plate 15, so as to fill the next sample chamber 33, until all irradiated samples 10 are filled, and then the valve on the irradiation sample preloading port pipe I9 is ​​closed.

[0041] The sample filling process can also be completed through gas delivery. The operation process is: open the valve on the pipeline connecting the gas connecting pipe I34 and the low-pressure gas tank, open the valve on the pipeline connecting the upstream of the irradiated sample pre-loading port connecting pipe I9 and the high-pressure gas tank, and transport the irradiated sample 10 to the sample chamber 33 through the pressure difference.

[0042] b) Irradiated sample injection operation: The reciprocating drive mechanism 24 drives the reciprocating shaft 21 to perform reciprocating motion, thereby rotating the rotating shaft 14 and driving the sample tray 15 to rotate. The sample compartment 33 on the sample tray 15 is monitored by the positioner III16 and the positioner II12 to see whether it is aligned with the irradiated sample injection port pipe II17. After alignment, the valve on the pipeline connecting the gas pipe II35 and the high-pressure gas tank is opened, and the valve on the pipeline connected to the low-pressure gas tank downstream of the injection port pipe II17 is opened. The irradiated sample 10 is transported from the sample compartment 33 to the designated device or position of the neutron activation analysis system through the pressure difference. Whether the irradiated sample 10 is discharged from the sample compartment 33 can be monitored by the sensor II18 on the injection port pipe II17. During the injection operation, the irradiated sample 10 in any sample compartment 33 on the sample tray 15 can be selected, without being restricted by the pre-installed order of the samples.

[0043] The fusion reactor irradiation sample injector of the present invention can realize the filling of multiple quantities and types of irradiation samples 10 and the injection operation of any sample in the sample tray 15.

[0044] In this embodiment, the sample tray 15 has a total of 10 sample chambers 33, which can be pre-loaded with 10 types of irradiated samples 10. When injecting samples, any one of the 10 types of irradiated samples 10 can be selected for injection.

[0045] [Example 2]

[0046] The structure of this embodiment is the same as that of the embodiment 1, except that the sample tray 15 has two sample chambers 33 in total, which can preload two types of irradiated samples 10. When injecting samples, any one of the two irradiated samples 10 can be selected for injection.

[0047] [Example 3]

[0048] The structure of this embodiment is the same as that of the embodiment 1, except that the sample tray 15 has a total of 16 sample compartments 33, which can be preloaded with 16 types of irradiated samples. When injecting samples, any one of the 16 types of irradiated samples 10 can be selected for injection.

[0049] [Example 4]

[0050] The structure of this embodiment is the same as that of embodiment 1, except that the sample tray 15 has a total of 32 sample compartments 33, which can pre-load 32 types of irradiated samples 10. When injecting samples, any one of the 32 types of irradiated samples 10 can be selected for injection.

[0051] Obviously, the fusion reactor irradiation sample injector of the present invention can realize the loading of multiple types and quantities of irradiated samples, can perform the injection operation of any sample, has the characteristics of flexible injection and efficient transmission, and at the same time has reliable sealing performance, meets the containment function of radioactive substances and harmful substances, has the characteristics of tritium compatibility, and can be used in reactor neutron measurement systems and fusion reactor neutron measurement systems, and has great technical advantages.

[0052] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A fusion reactor irradiation sample injector, characterized in that: The sample injector comprises a housing I (1), a gear plate (23) installed inside the housing I (1), a reciprocating shaft (21), a sliding bearing I (25) and a sliding bearing II (26), a housing II (3), a sample plate (15) installed inside the housing II (3), a rotating shaft (14), and a flange I (2); Shell I (1) is connected to shell II (3) via flange I (2); The top of the housing II (3) is provided with a flange II (7) and a flange III (19); the pipe I (9) is fixedly connected to the housing II (3) via the flange II (7), and a sensor I (8) is installed on the pipe I (9); the pipe II (17) is fixedly connected to the housing II (3) via the flange III (19), and a sensor II (18) is installed on the pipe II (17); the inner upper surface of the housing II (3) is provided with a positioner I (11) and a positioner III (16); The rotating shaft (14) is installed in a rotating bearing I (13) located in the housing II (3) and a rotating bearing II (22) located in the housing I (1); the reciprocating shaft (21) is slidably connected with the sliding bearing I (25) and the sliding bearing II (26); a rack is provided on the reciprocating shaft (21), and the rack on the reciprocating shaft (21) is meshed with the gear plate (23); The gear plate (23) and the sample plate (15) are mounted on the rotating shaft (14); At least one sample chamber (33) is provided on the sample tray (15); A groove II (32) is provided at the top position of the sample chamber (33) on the sample disk (15), a buffer pad (5) is provided at the bottom of the sample chamber (33), a channel II (31) is provided at the center position of the bottom of the sample chamber (33), and a channel I (30) is provided along the radial direction of the sample disk (15); the axis of the channel I (30) is perpendicular to the axis of the channel II (31), one end of the channel I (30) passes through the outer peripheral surface of the sample disk (15), and the other end is connected to the channel II (31), and the top of the channel II (31) is connected to the sample chamber (33); a groove I (29) is provided on the outer peripheral surface of the sample disk (15), and the groove I (29) is respectively located on the upper and lower sides of the channel I (30); and the upper surface of the sample disk (15) is installed with positioners II (12) equal in number to the sample chamber (33), and the positioners II (12) are located on the plane formed by the axis of the sample chamber (33) and the axis of the sample disk (15).

2. A fusion reactor irradiation sample injector according to claim 1, characterized in that: The sample bins (33) are evenly distributed on the sample tray (15), the axis of the sample bins (33) is parallel to the axis of the sample tray (15), and the distance from the axis of each sample bin (33) to the axis of the sample tray (15) is equal.

3. A fusion reactor irradiation sample injector according to claim 2, characterized in that: A connecting pipe III (20) is installed on the outer surface of the cylinder of the shell II (3), and the connecting pipe III (20) is connected to the interior of the shell II (3); the axis of the connecting pipe III (20) is located on the radial line of the shell II (3).

4. A fusion reactor irradiation sample injector according to claim 3, characterized in that: The axis center line of the reciprocating shaft (21) and the axis center line of the gear plate (23) are perpendicular to each other; one end of the reciprocating shaft (21) passes through the flange IV (27) and the bellows (28) and is connected to the reciprocating drive mechanism (24); the flange IV (27) is fixedly connected to the housing I (1), one end of the bellows (28) is fixedly connected to the flange IV (27), and the other end of the bellows (28) is fixedly connected to the reciprocating shaft (21).

5. A fusion reactor irradiation sample injector according to claim 4, characterized in that: The connecting pipe III (20) is connected to both the gas connecting pipe I (34) and the gas connecting pipe II (35).

6. A fusion reactor irradiation sample injector according to claim 5, characterized in that: A sealing ring I (4) is installed in the groove I (29) on the outer peripheral surface of the sample plate (15), and the sealing ring I (4) is slidably connected to the inner peripheral surface of the shell II (3).

7. A fusion reactor irradiation sample injector according to claim 6, characterized in that: A sealing ring II (6) is installed in the groove II (32) at the top of the sample chamber (33), and the sealing ring II (6) is slidably connected to the inner upper surface of the housing II (3).

8. A fusion reactor irradiation sample injector according to claim 7, characterized in that: The shell I (1) is in the shape of a cube or a cuboid, the shell II (3) is in the shape of a cylinder; and the sample tray (15) is in the shape of a cylinder.

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