Pressurized water reactor nuclear fuel cladding damage release experimental device

Abstract

The utility model discloses a pressurized water reactor nuclear fuel cladding damage release experiment device which comprises a single-flow-channel simulation piece, a simulation porous experiment rod and a transmission mechanism. The simulation porous experiment rod is inserted into the single-flow-channel simulation piece in a penetrating manner; the simulation porous experiment rod comprises an experiment rod shell and an end plug, a plurality of experiment holes are longitudinally distributed in the experiment rod shell, the end plug is arranged in the experiment rod shell in a matched mode, an experiment air outlet hole, an experiment air inlet hole and a transmission connector are formed in the end plug, and the experiment air outlet hole corresponds to the experiment holes and is located in the longitudinal side face of the end plug. The experimental air inlet and the transmission interface are respectively positioned on the end surface of the end plug; the transmission mechanism is connected with the transmission interface and drives the end plug to move back and forth in the experiment rod shell along the longitudinal direction of the experiment rod shell, so that the experiment air outlet hole is relatively communicated with one experiment hole. According to the utility model, the supervision indication nuclide release behavior research under different simulated fuel cladding damage conditions can be realized; the transmission mechanism drives the end plug to move, remote control can be carried out, and the device is suitable for radioactive experiments.

Description

Technical Field

[0001] This utility model relates to the field of nuclear fuel testing technology, and in particular to a test device for the release of nuclear fuel cladding damage in pressurized water reactors. Background Technology

[0002] During nuclear power plant operation, fuel cladding may be damaged by various physicochemical factors such as abrasion and chemical corrosion. Fission products within the fuel rods can then enter the primary coolant through the breach, potentially increasing radiation dose levels for operation and maintenance personnel and even necessitating reactor shutdown for repairs. As the first line of defense against radioactive nuclides, the integrity monitoring of the fuel cladding is a crucial component of radiochemical technical specifications. In the event of damage, the extent of the damage and the severity of the accident must be assessed promptly based on monitoring data to determine whether a reactor shutdown is necessary. Accurate damage assessment requires extensive experimentation to determine the relationship between the degree of damage and the monitoring indicator nuclides in the coolant. Currently, most international experiments are conducted on experimental reactors, with relatively fixed experimental variables, resulting in limited scalability of the experimental results. Among these, fuel cladding damage release simulation experimental devices, as key components, currently lack practically applicable designs.

[0003] An existing reactor cladding failure simulation test bench includes fuel rod simulators, end plugs, sealing sleeves, and a core single-channel simulator. By detachably installing the fuel rod simulators onto the core single-channel simulator, the simulated failure closure is manually achieved by controlling the end plugs on the heating rods through a lifting handle. The test rod shell is equipped with interfaces for measuring pressure, temperature, and humidity instruments, as well as an exhaust port. It can be used to simulate cladding failure under various operating conditions and to measure gas release and internal pressure changes under different hydraulic conditions, different types of fractures, and different internal temperature fields. However, the experimental platform has the following shortcomings: (1) There is only one experimental hole on the outer shell of the experimental rod. Each experiment can only achieve one simulated break size. The simulation experimental platform needs to be disassembled and the simulated rod replaced in order to achieve the simulated break replacement; (2) The experimental hole is manually closed by lifting the handle to control the end plug on the heating rod. This method cannot be remotely controlled and is not suitable for radioactive experiments; (3) The gas heating temperature is controlled by the built-in heating rod. During the long-term experiment, the transport medium will enter the inner shell of the experimental rod through the experimental hole and corrode the built-in heating rod. After the corrosion products of the heating rod fall off, they can easily block the experimental hole, thus affecting the normal conduct of the experiment. Utility Model Content

[0004] The technical problem to be solved by this invention is to provide an improved experimental device for releasing nuclear fuel cladding damage in pressurized water reactors.

[0005] The technical solution adopted by this utility model to solve its technical problem is: to provide a pressurized water reactor nuclear fuel cladding failure and release experimental device, including a single-channel simulation component, a simulated porous experimental rod and a transmission mechanism; the simulated porous experimental rod is inserted into the single-channel simulation component.

[0006] The simulated porous experimental rod includes an outer shell and a hollow end plug. The outer shell has multiple longitudinally distributed experimental holes of varying sizes and / or shapes. The end plug fits inside the outer shell and has an experimental vent, an experimental inlet, and a transmission interface. The experimental vent is located on the longitudinal side of the end plug, corresponding to the experimental hole. The experimental inlet and transmission interface are located on the end face of the end plug.

[0007] The transmission mechanism is connected to the transmission interface and is used to drive the end plug to move back and forth along the longitudinal direction of the experimental rod shell inside the experimental rod shell, so that the experimental vent is in communication with one of the experimental holes.

[0008] In some embodiments, the plurality of experimental holes are equidistantly distributed along the longitudinal direction of the experimental rod shell, and the distance between two adjacent experimental holes is greater than the height of the end plug.

[0009] In some embodiments, the outer wall of the experimental rod shell is provided with a longitudinal marking line, which extends along the center or one side of the longitudinally distributed experimental holes.

[0010] In some embodiments, the end plug includes a cylindrical tube and a high-temperature resistant sealant fitted to opposite end faces of the cylindrical tube;

[0011] The cylindrical tube's outer peripheral surface mates with the inner wall of the experimental rod's outer shell. The experimental vent is located on the outer peripheral surface of the cylindrical tube. The experimental inlet and transmission interface are respectively located on one end face of the cylindrical tube and penetrate the corresponding high-temperature resistant sealant.

[0012] In some embodiments, the simulated porous experimental rod further includes a temperature measuring interface and a pressure measuring interface disposed on the end plug, or the simulated porous experimental rod further includes a temperature instrument and a pressure instrument inserted into the end plug.

[0013] In some embodiments, the single-channel simulator includes a bottom-sealed single-channel housing, a mounting plate that is removably and sealingly fitted onto the open top of the single-channel housing, and a simulated flow channel bar;

[0014] The lower end or bottom of the single-channel shell is provided with a medium inlet, and the upper end of the single-channel shell is provided with a medium outlet; the mounting plate is provided with a plurality of mounting holes that communicate with the interior of the single-channel shell, and the simulated flow channel rod and the simulated porous experimental rod are respectively inserted into the single-channel shell through the corresponding mounting holes.

[0015] In some embodiments, the transmission mechanism includes a transmission rod for connecting to the transmission interface and a drive unit for connecting to and driving the transmission rod to move up and down.

[0016] In some embodiments, the pressurized water reactor nuclear fuel cladding breach release experimental apparatus further includes a gas supply mechanism;

[0017] The gas supply mechanism includes a gas storage tank, a gas delivery pipe connected between the gas storage tank and the experimental air inlet, and a gas valve installed on the gas delivery pipe; the gas storage tank is equipped with a gas storage heating unit, and the gas storage tank is connected to a pressurization unit.

[0018] In some embodiments, the gas supply mechanism further includes a gas distribution tank connected to the gas storage tank and gas cylinders respectively connected to the gas distribution tank.

[0019] In some embodiments, the pressurized water reactor nuclear fuel cladding breach release experimental apparatus further includes a control terminal; the control terminal is connected to the transmission mechanism and the gas supply mechanism, and controls the start and stop of the transmission mechanism and the gas supply mechanism respectively.

[0020] The beneficial effects of this invention are: the experimental holes on the simulated porous experimental rod vary in size and shape, enabling the study of monitored nuclide release behavior under different simulated fuel cladding damage conditions; the movement of the end plug is driven by a transmission mechanism, replacing the manual handle of the prior art, which allows for remote control and is suitable for radioactive experiments. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0022] Figure 1 This is a connection diagram of an experimental device for releasing nuclear fuel cladding damage in a pressurized water reactor according to an embodiment of this utility model;

[0023] Figure 2 This is a schematic diagram of the longitudinal cross-sectional structure of a simulated porous experimental rod in a pressurized water reactor nuclear fuel cladding failure and release experimental device according to an embodiment of this utility model.

[0024] Figure 3 This is a schematic diagram of the connection of the gas supply mechanism and other components in the pressurized water reactor nuclear fuel cladding failure and release experimental device according to an embodiment of this utility model. Detailed Implementation

[0025] To provide a clearer understanding of the technical features, objectives, and effects of this utility model, the specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0026] like Figure 1 and Figure 2 As shown, an embodiment of the pressurized water reactor nuclear fuel cladding breach and release experimental device of this utility model may include a single-channel simulator 1, a simulated porous experimental rod 2, a transmission mechanism 3, and a control terminal 4. The simulated porous experimental rod 2 is inserted into the single-channel simulator 1, and the transmission mechanism 3 is connected to the simulated porous experimental rod 2 to drive the related structural movements of the simulated porous experimental rod 2. The control terminal 4 is connected to the transmission mechanism 3 and is used to control the start and stop of the transmission mechanism 3, enabling remote control of the transmission mechanism 3.

[0027] The single-channel simulator 1 may structurally include a single-channel housing 11, a mounting plate 12, and several simulated flow channel rods 13. The single-channel housing 11 has a structure that is closed at one end and open at the other. Taking its vertical placement in use as an example, the top of the single-channel housing 11 is open. The mounting plate 12 is sealed to the top of the single-channel housing 11 using high-temperature resistant gaskets and fasteners (such as bolts), thus sealing the top of the single-channel housing 11. Furthermore, the mounting plate 12 is removable from the top of the single-channel housing 11 for easy replacement as needed.

[0028] The single-channel housing 11 has a medium inlet 101 at its lower end or bottom and a medium outlet 102 at its upper end. The transport medium enters the single-channel housing 11 through the medium inlet 101 and exits through the medium outlet 102. The single-channel simulation component 1 is installed and connected to an experimental circuit or experimental tank or other experimental device through the medium inlet 101 and the medium outlet 102.

[0029] The mounting plate 12 has several mounting holes 120, which penetrate the mounting plate 12 and communicate with the interior of the single-channel housing 11. One mounting hole 120 is used for the insertion of a simulated porous experimental rod 2, which passes through the mounting hole 120 and is inserted into the single-channel housing 11. The remaining mounting holes 120 can be used for the insertion of simulated flow channel rods 13, each of which passes through its corresponding mounting hole 120 and is inserted into the single-channel housing 11. The simulated porous experimental rods 2 and 13 are sealed to the mounting plate 12 using high-temperature resistant gaskets.

[0030] The simulated porous experimental rod 2 and the simulated flow channel rod 13 are designed to mimic the shape of the reactor core fuel rods, that is, the simulated porous experimental rod 2 and the simulated flow channel rod 13 have the same shape as the reactor core fuel rods.

[0031] exist Figure 1In the embodiment shown, the mounting plate 12 is provided with four mounting holes 120 arranged in a predetermined manner and having the same diameter. The ratio of the center distance to the diameter of adjacent mounting holes 120 can be set according to the experimental requirements, so that the grid pitch ratio of the simulated rods in the single-channel simulator 1 is equivalent to the grid pitch ratio of the fuel rods in the reactor core, thereby making the flow channel inside the single-channel simulator 1 similar to the flow channel in the real reactor core.

[0032] The simulated porous experimental rod 2 may further include an experimental rod shell 21 and a hollow end plug 22. The bottom of the experimental rod shell 21 is closed and the top is open. The experimental rod shell 21 has a plurality of longitudinally distributed experimental holes 210. The end plug 22 fits inside the experimental rod shell 21 and has an experimental vent 220. The end plug 22 can move back and forth along the longitudinal direction of the experimental rod shell 21 within the experimental rod shell 21 so that its experimental vent 220 communicates with any of the experimental holes 210.

[0033] Multiple experimental holes 210 have different sizes and / or shapes, each corresponding to a different damage state, to simulate various damage situations that may exist in the actual fuel rod cladding.

[0034] The end plug 22 is also provided with an experimental air inlet 221 and a transmission interface 222. The experimental air inlet 221 is used to connect to the gas supply mechanism to receive the experimental gas provided by the gas supply mechanism. The transmission interface 222 is used to connect to the transmission mechanism 3. The transmission mechanism 3 drives the end plug 22 to move back and forth along the longitudinal direction of the experimental rod shell 21 inside the experimental rod shell 21, thereby making the experimental air outlet 220 on the end plug 22 communicate with an experimental hole 210.

[0035] Corresponding to the longitudinal distribution of the experimental holes 210 on the outer shell 21 of the experimental rod, the experimental vent 220 is set on the longitudinal side of the end plug 22, while the experimental inlet 221 and the transmission interface 222 are respectively set on the end face (top surface) of the end plug 22, so as to avoid interference or blockage of the experimental vent 220 by the experimental inlet 221 and the transmission interface 222.

[0036] Specifically, on the outer shell 21 of the experimental rod, multiple experimental holes 210 can be equidistantly distributed in the longitudinal direction, and the distance (center distance) L between two adjacent experimental holes 210 is greater than the height l of the end plug 22, so that during the experiment, the experimental vent 220 on the end plug 22 can only be connected to one experimental hole 210 at a time.

[0037] Furthermore, the outer wall of the experimental rod shell 21 is provided with a longitudinal marking line 23. The longitudinal marking line 23 extends along the center or one side of the longitudinally distributed experimental holes 210, which facilitates the insertion of the end plug 22 into the experimental rod shell 21 with its experimental vent 220 facing and along the longitudinal marking line 23 when it is installed inside the experimental rod shell 21. This avoids the situation where the experimental vent 220 cannot cover the experimental holes 210. The longitudinal marking line 23 can be a marking line of a conspicuous color, or a marking line that is raised on the outer wall of the experimental rod shell 21, or a marking line that is raised and has a conspicuous color.

[0038] The end plug 22 may further include a cylindrical tube 201 and high-temperature resistant sealant 202 fitted on opposite end faces of the cylindrical tube 201. The cylindrical tube 201 is a sealed cylinder made of metal material, and its height direction corresponds to the longitudinal direction of the experimental rod shell 21. The outer peripheral surface of the cylindrical tube 201 fits with the inner wall surface of the experimental rod shell 21. The experimental vent 220 is provided on the outer peripheral surface of the cylindrical tube 201, and the experimental vent 221 and the transmission interface 222 are respectively provided on one end face of the cylindrical tube 201 facing the mounting plate 12 and penetrate the corresponding high-temperature resistant sealant 202.

[0039] The high-temperature resistant sealant 202 on both ends of the cylindrical tube 201 seals the gap between its end face and the inner wall of the outer shell 11 of the experimental rod. The experimental gas enters the end plug 22 through the experimental inlet 221 and then exits from the experimental outlet 220 and the relatively connected experimental hole 210, without leaking out through the end of the end plug 22.

[0040] The simulated porous experimental rod 2 also includes a temperature measuring interface (not shown) and a pressure measuring interface (not shown) disposed on the end plug 22. Alternatively, the simulated porous experimental rod 2 also includes a temperature instrument 24 (or thermocouple) and a pressure instrument 25 inserted into the end plug 22. The temperature and pressure of the gas inside the end plug 22 are detected by the temperature instrument 23 and the pressure instrument 25, and the detected information can be sent to the control terminal 4 to achieve remote monitoring.

[0041] Combination Figures 1 to 3 The transmission mechanism 3 includes a transmission rod 31 and a drive unit 32. The transmission rod 31 can enter the experimental rod housing 21 from the open top and connect to the transmission interface 222 on the end plug 22. The drive unit 32 connects to and drives the transmission rod 31 to move up and down, causing the end plug 22 to move back and forth along its longitudinal direction within the experimental rod housing 21.

[0042] Alternatively, the drive unit 32 may include a motor, and the transmission rod 31 may be a ball screw, converting the rotational motion of the motor into linear motion to drive the end plug 22 to move longitudinally. The control terminal 4 connects to and controls the drive unit 32 to achieve movement control of the transmission rod 31 and obtain the movement distance and position of the end plug 22. Preferably, the transmission accuracy of the ball screw is not less than 1μm.

[0043] Furthermore, in some embodiments, the pressurized water reactor nuclear fuel cladding breach release experimental apparatus also includes a gas supply mechanism 5 to provide experimental gas (simulated radioactive gas) to the simulated porous experimental rod 2.

[0044] Combination Figure 2 and Figure 3 The gas supply mechanism 5 may include a gas storage tank 51, a gas delivery pipe 52 connected between the gas storage tank 51 and the experimental gas inlet 221, a gas valve 53 installed on the gas delivery pipe 52, and a first flow controller 54. The control terminal 4 is connected to the gas valve 53 and controls its opening and closing, thereby controlling the flow of experimental gas. The first flow controller 54 controls the gas flow rate of the gas delivery pipe 52 and can send real-time monitored flow information to the control terminal 4, which can then monitor the flow.

[0045] A filter may also be provided at one end of the gas supply pipe 52 near the experimental air inlet 221 to filter out particulate impurities in the gas.

[0046] The gas storage tank 51 is equipped with a gas storage heating unit 55, which heats the experimental gas inside the gas storage tank 51 to the required experimental temperature. The gas storage tank 51 is connected to a pressurization unit 56, which is used to regulate the pressure of the experimental gas inside the gas storage tank 51. Through the cooperation of the gas storage heating unit 55 and the pressurization unit 56, experimental gases with various temperature and pressure requirements can be provided to the end plug 22.

[0047] The gas storage heating unit 55 includes, but is not limited to, heating rods or heating wires. The pressurization unit 56 includes, but is not limited to, a booster pump.

[0048] The gas storage heating unit 55 is installed inside the gas storage tank 51 to avoid contact with the transport medium and corrosion, which could lead to corrosion products detaching and clogging the test holes.

[0049] The gas storage tank 51 is also equipped with a pressure gauge 511 and a temperature gauge 512, which are used to detect the gas pressure and temperature inside the gas storage tank 51, respectively. Furthermore, the pressure gauge 511 and the temperature gauge 512 are connected to the control terminal 4 to send the detected information to the control terminal 4. The control terminal 4 can control the start and stop of the gas storage heating unit 55 and the pressurization unit 56 based on the acquired gas pressure and temperature information.

[0050] As needed, the gas supply mechanism 5 may also include a gas distribution tank 57 connected to the gas storage tank 51 and gas cylinders 58 connected to the gas distribution tank 57 respectively. The gas distribution tank 57 is connected to gas cylinders 58 that contain different experimental gases according to experimental requirements. Different experimental gases can be quantitatively delivered to the gas distribution tank 57 for mixing, and then delivered from the gas distribution tank 57 to the gas storage tank 51.

[0051] A valve 571 and a second flow controller 572 are installed on the pipeline connecting the gas distribution tank 57 and the gas storage tank 51. The valve 571 and the second flow controller 572 are connected to the control terminal 4, which can control the opening and closing of the valve and receive flow information.

[0052] The gas distribution tank 57 is equipped with a gas distribution heating unit 573, which heats the gas in the gas distribution tank 57 to the required experimental temperature. The gas distribution tank 57 may also be connected to a booster pump 574 to regulate the pressure of the gas in the gas distribution tank 57. The gas distribution heating unit 573 includes, but is not limited to, heating rods or heating wires.

[0053] Similarly, the gas distribution tank 57 is also equipped with a pressure gauge and a temperature gauge, which are used to detect the gas pressure and temperature inside the gas distribution tank 57, respectively. These pressure gauges and temperature gauges are also connected to the control terminal 4, sending the detected information to the control terminal 4.

[0054] The control terminal 4 is connected to the transmission mechanism 3 and various valves, pressure gauges and temperature gauges, etc., to realize remote control of them.

[0055] This invention is capable of monitoring the release behavior of nuclides under different simulated fuel cladding damage conditions. It has the following advantages: (1) The outer shell of the experimental rod is equipped with multiple experimental holes of different sizes and shapes to simulate the possible damage conditions of the actual fuel cladding. The end plug is connected to simulated radioactive gas. Only by moving the end plug to align the experimental outlet on the end plug with a specific experimental hole required for the experiment, the experimental gas can be released through the specific experimental hole. There is no need to disassemble the simulated experimental platform during the experiment, which greatly simplifies the experimental process and reduces the experimental cost; (2) The transmission rod of the transmission mechanism is connected to the end plug, which can remotely control the longitudinal movement of the transmission rod to realize the longitudinal movement of the end plug in the simulated multi-hole experimental rod, realizing the automated control of the selection and closure of specific experimental holes, which is suitable for radioactive experiments; (3) The temperature and pressure of the experimental gas are regulated and controlled through the gas supply mechanism. The temperature and pressure of the experimental gas are remotely adjustable, avoiding the risk of impurities in the experimental gas clogging the experimental holes.

[0056] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A test apparatus for releasing nuclear fuel cladding from a pressurized water reactor, characterized in that, It includes a single-channel simulator, a simulated porous experimental rod, and a transmission mechanism; the simulated porous experimental rod is inserted into the single-channel simulator. The simulated porous experimental rod includes an outer shell and a hollow end plug. The outer shell has multiple longitudinally distributed experimental holes of varying sizes and / or shapes. The end plug fits inside the outer shell and has an experimental vent, an experimental inlet, and a transmission interface. The experimental vent is located on the longitudinal side of the end plug, corresponding to the experimental hole. The experimental inlet and transmission interface are located on the end face of the end plug. The transmission mechanism is connected to the transmission interface and is used to drive the end plug to move back and forth along the longitudinal direction of the experimental rod shell inside the experimental rod shell, so that the experimental vent is in communication with one of the experimental holes.

2. The pressurized water reactor nuclear fuel cladding breach and release experimental apparatus according to claim 1, characterized in that, The plurality of experimental holes are equidistantly distributed along the longitudinal direction of the outer shell of the experimental rod, and the distance between two adjacent experimental holes is greater than the height of the end plug.

3. The pressurized water reactor nuclear fuel cladding breach and release experimental apparatus according to claim 1, characterized in that, The outer wall of the experimental rod shell is provided with longitudinal marking lines, which extend along the center or one side of the longitudinally distributed experimental holes.

4. The pressurized water reactor nuclear fuel cladding breach and release experimental apparatus according to claim 1, characterized in that, The end plug includes a cylindrical tube and high-temperature resistant sealant fitted to the opposite end faces of the cylindrical tube; The cylindrical tube's outer peripheral surface mates with the inner wall of the experimental rod's outer shell. The experimental vent is located on the outer peripheral surface of the cylindrical tube. The experimental inlet and transmission interface are respectively located on one end face of the cylindrical tube and penetrate the corresponding high-temperature resistant sealant.

5. The pressurized water reactor nuclear fuel cladding breach and release experimental apparatus according to claim 1, characterized in that, The simulated porous experimental rod also includes a temperature measuring interface and a pressure measuring interface disposed on the end plug, or the simulated porous experimental rod also includes a temperature instrument and a pressure instrument inserted into the end plug.

6. The pressurized water reactor nuclear fuel cladding breach and release experimental apparatus according to claim 1, characterized in that, The single-channel simulation component includes a bottom-sealed single-channel housing, a detachable and sealed mounting plate fitted onto the open top of the single-channel housing, and a simulation channel bar; The lower end or bottom of the single-channel shell is provided with a medium inlet, and the upper end of the single-channel shell is provided with a medium outlet; the mounting plate is provided with a plurality of mounting holes that communicate with the interior of the single-channel shell, and the simulated flow channel rod and the simulated porous experimental rod are respectively inserted into the single-channel shell through the corresponding mounting holes.

7. The pressurized water reactor nuclear fuel cladding breach and release experimental apparatus according to claim 1, characterized in that, The transmission mechanism includes a transmission rod for connecting to the transmission interface and a drive unit for connecting and driving the transmission rod to move up and down.

8. The pressurized water reactor nuclear fuel cladding breach and release experimental apparatus according to any one of claims 1-7, characterized in that, The pressurized water reactor nuclear fuel cladding breach release experimental device also includes a gas supply mechanism; The gas supply mechanism includes a gas storage tank, a gas delivery pipe connected between the gas storage tank and the experimental air inlet, and a gas valve installed on the gas delivery pipe; the gas storage tank is equipped with a gas storage heating unit, and the gas storage tank is connected to a pressurization unit.

9. The pressurized water reactor nuclear fuel cladding breach and release experimental apparatus according to claim 8, characterized in that, The gas supply mechanism also includes a gas distribution tank connected to the gas storage tank and gas cylinders connected to the gas distribution tank.

10. The pressurized water reactor nuclear fuel cladding breach and release experimental apparatus according to claim 8, characterized in that, The pressurized water reactor nuclear fuel cladding breach release experimental device also includes a control terminal; the control terminal is connected to the transmission mechanism and the gas supply mechanism, and controls the start and stop of the transmission mechanism and the gas supply mechanism respectively.

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