JPH0468074B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a fuel element end plug welding device that can be used in the manufacturing process of nuclear reactor fuel elements.

(b) Prior Art A fuel element for a nuclear reactor is manufactured as shown in FIG. That is, first, as shown in FIG. 1a, pellets c of uranium oxide or the like are filled into a stainless steel pipe b which is airtightly covered with an end plug a at one end.
Thereafter, as shown in FIG. 1b, a breathable temporary end plug d is removably attached to the other end of the stainless steel pipe b. In this state, degassing and He replacement treatment as described below are performed, and then the temporary end plug is removed and a spring e and a full-fledged end plug f are installed, and this end plug f and the stainless steel The joint g with the pipe b is circularly welded in an airtight manner, and the welding point k is closed by melting to complete the pressure welding. Note that pressure welding here refers to inserting the end plug of the fuel element h that has undergone the circular welding into a pressurizing chamber, introducing high-pressure He gas into the pressurizing chamber, and discharging the He gas. This is an operation in which fuel is filled into the fuel element h through a small hole m provided in the end plug f, and then the open end k of the small hole m is melted and closed.

By the way, such welding processing has conventionally been performed using a batch type device. That is, the conventional device consists of a single chamber in which about 20 to 30 semi-finished fuel elements h' can be held by a barrel as shown in Fig. 1b, and a welding chamber adjacent to this chamber. The welding chamber is provided with a circumferential welding section and a pressure welding section along a single wire. First, the inside of the chamber is evacuated, and then heated for a required period of time to degas.
In other words, inside the pellet c or the stainless steel pipe b
Remove the moisture contained within. When the degassing process is completed, He gas is introduced into the chamber to perform He replacement and cooling at the same time.
After the fuel elements in the chamber have been subjected to degassing and He replacement treatment in this way, the fuel elements are pulled out from the chamber one by one, and the axial end of the fuel element is attached to the circumferential weld in the welding chamber. Insert up to
After replacing the temporary end plug and the final end plug in this welding chamber, circular welding is performed and the welding is pulled back into the chamber. In this manner, after completing a full number of welds, the fuel element is retained in the chamber until its end plug weld has cooled to a suitable temperature. Then, the fuel elements are again pulled out one by one from the chamber along the same wire path as described above and pressure welded. That is, the end plugs of each of the fuel elements are passed through the circumferential welding part of the welding chamber and inserted into the pressure welding part beyond that, and the aforementioned pressure welding is applied to the end plugs. Note that the reason for returning the fuel element to the chamber to cool it after lap welding is that if pressure welding is performed immediately after lap welding, the heat remaining in the end plug of the fuel element will cause the fuel element to cool down in the chamber. This is because the sealing member may deteriorate or be damaged.

Although it is possible to perform welding on the end plug of the fuel element in this manner, such conventional welding is of a batch type and is therefore inefficient. In particular, with such a configuration, the pressure welding part stops its function when circular welding is being performed, and conversely, circular welding cannot be performed when pressure welding is being performed. Therefore, there is a problem in that it is difficult to increase the throughput per hour without increasing the number of devices.

(c) Purpose The present invention was made with attention to the above-mentioned circumstances, and it is possible to sequentially and continuously perform the processing steps of circumferential welding, cooling, and pressure welding.
It is an object of the present invention to provide an end plug welding device for a fuel element that can shorten takt time and increase throughput reasonably and effectively.

(d) Configuration In order to achieve the above object, the present invention provides a fuel element end plug welding device with a He gas atmosphere inside and an inlet port for introducing a fuel element into the end wall of the device, which has different inlet ports. a cooling chamber having first and second inlet/outlet ports provided at positions and an outlet port for leading out the fuel element; and a cooling chamber disposed within the cooling chamber and fed into the cooling chamber through the inlet port. a barrel for receiving a fuel element and sequentially moving it in parallel to a position facing each of the ports; a circumferential welded portion located adjacent to the cooling chamber and corresponding to the first outlet port; and a second outlet port. and a welding chamber having a pressure welded portion at a portion corresponding to the welding chamber, and when the fuel element held in the barrel reaches the first lead-in/out port and the second lead-in/out port, The fuel element is temporarily drawn out to the circumferential welding part and the pressurized welding part through corresponding ports to perform welding processing, and the separation distance between the first lead-in/out port and the second lead-out port is The present invention is characterized in that the temperature is set to a value that allows the end plug portion of the fuel element heated by circular welding to be cooled down to an appropriate temperature before reaching the pressure welding portion.

(e) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 2, there is a filling device 1, a receiving lateral movement device 2, a receiving airlock chamber 3, a degassing chamber 4, and an airlock chamber 5 which also serves as a primary cooling chamber.
A secondary cooling chamber 6 for He replacement is provided in series.

The filling device 1 loads a spring i, a spacer j, and a pellet c into a stainless steel pipe b which has an end plug a airtightly attached to one end thereof, and allows a temporary end plug d to be removed from the other end of the stainless steel pipe b. The semi-finished fuel element h' produced in this way is sent out in the axial direction along the first surface line A. A gate valve 7 is interposed between the filling device 1 and the receiving lateral movement device 2. Further, the receiving lateral movement device 2 is configured to move the fuel element h' fed along the first line A in parallel to the second line B, and send it out along the second line B. There is. A second gate valve 8 is provided between the lateral movement device 2 and the first airlock chamber 3. The receiving airlock chamber 3 has a sealed structure connected to an exhaust device 9, and the interior thereof can be switched between an atmospheric atmosphere and a vacuum atmosphere. A third gate valve 11 is interposed between the aerodynamic chamber 3 and the degassing chamber 4. The degassing chamber 4 is formed in a sealed container 13 connected to an exhaust device 12, and houses a barrel 14 for holding a fuel element therein. The barrel 14 is made by connecting a plurality of discs 14a with their axes aligned, and a plurality of holding holes 14b are bored at equal pitches in the circumferential direction near the periphery of each disc 14a. . Then, each holding hole 14 with which the wires are connected
One fuel element h' is held at b and rotated intermittently one pitch at a time. Incidentally, an inlet port 15 corresponding to the second line B and an outlet port 16 corresponding to a third line C parallel to the second line B are bored in the end wall of the sealed container 13. be. Each time the barrel 14 finishes intermittent rotation, a different holding hole 14b is opened to the inlet port 15.
and facing the outlet port 16. Furthermore, a heater 17 is disposed within the sealed container 13 for heating the fuel element h' that is held in the barrel 14 and rotates. and,
A gate valve 20 is interposed between the outlet port 16 of the degassing chamber 4 and the second aerodynamic chamber 5. The second aerodynamic chamber 5 has an exhaust system 18
It has a sealed structure including a He gas supply device 19 and a He gas supply device 19, and the interior can be switched between a vacuum atmosphere and a He gas atmosphere. and,
A gate valve 21 is interposed between the aerodynamic chamber 5 and the secondary cooling chamber 6. Secondary cooling chamber 6
is formed in a sealed container 24 connected to an exhaust device 22 and a He gas supply device 23, and houses a barrel 25 for holding a fuel element having the same configuration as the barrel 14. . Furthermore, on one end wall of the sealed container 24, there is provided the third wire C.
An inlet port 26 corresponding to the third line C and an outlet port 27 corresponding to the fifth line E parallel to the third line C are bored in the other end wall. A first lead-out port 28 corresponding to the fourth wire D and a second lead-out port 29 corresponding to the fifth wire E are bored. The inside of this secondary cooling chamber 6 is always maintained in a He gas atmosphere. That is, this secondary cooling chamber 6 is sufficiently evacuated before steady operation. After the steady operation for replacing He gas is started, this He gas atmosphere is always maintained unless the oxygen or moisture conditions deteriorate. Therefore, the exhaust device 22 is not used during steady operation. It should be noted that the temperature of the He gas may gradually rise in the secondary cooling chamber 6, so the He gas is circulated.
A cooler (not shown) performs forced cooling to control the temperature inside the chamber.

Further, the first and second inlet/outlet ports 28 and 29 of this secondary cooling chamber 6 are communicated with a welding chamber 33 via gate valves 31 and 32. The welding chamber 33 has a sealed structure, and the interior thereof is maintained in a He gas atmosphere. Therefore, like the secondary cooling chamber 6 mentioned above, it is necessary to fully exhaust the He
Fill with gas. Thereafter, this atmosphere is maintained at all times except when the oxygen and moisture conditions have deteriorated, and no exhaust is performed during steady operation. A circumferential welding portion 34 is provided in a portion of this welding chamber 33 corresponding to the fourth wire D, and the fifth wire E
A pressure welding portion 35 is provided at a location corresponding to.
The circumferential welding part 34 includes a main chuck 36 that grips the stainless steel pipe b of the fuel element h' and rotates it around its axis, and a main chuck 36 that grips the end plug d (or f) of the fuel element h' (or h). a sub-chuck 37 that rotates around its axis, and both chucks 3
A welding torch 38 with a nozzle facing the fuel element insertion passage between the fuel element 6 and 37 is provided. Note that the subchuck 37 can also move forward and backward in the axial direction of the fuel element h. On the other hand, the pressure welding part 35 includes a chuck 39 that grips the stainless steel pipe b portion of the fuel element h and fixes the fuel element h by rotating it around the axis to a fixed position, and an end plug of the fuel element h. A pressurizing chamber 41 that airtightly holds the welded portion, and a welding torch 42 having a nozzle facing the outer periphery of an end plug f of a fuel element h inserted into the pressurizing chamber 41 are provided. Note that the pressurizing chamber 41 can move forward and backward in the axial direction of the fuel element h.

The first lead-in/out port 28 and the second
The distance between the outlet port 29 and the end plug of the fuel element h heated by circular welding is the pressure welded part 35.
The temperature is set to a value that allows the pressure chamber 41 to be cooled to an appropriate temperature, that is, a temperature that does not adversely affect the seal member provided in the shaft seal portion 41a of the pressurizing chamber 41.

Note that a multifunctional hand 4 is installed in this welding chamber 33.
3 and a crane 44 for suspending equipment pallets 45 is provided. Further, an equipment insertion chamber 46 is provided adjacent to this welding chamber 33. This equipment insertion chamber 46 is a welding chamber 33 in steady operation in a He gas atmosphere.
This is for loading and unloading an equipment pallet 45 loaded with equipment such as end plugs, and the outer door 4 communicates with the atmosphere.
7 and an inner door 48 communicating with the welding chamber 33.

Further, the fuel element h sent out in the axial direction from the outlet port 27 of the secondary cooling chamber 6 through the gate valve 49 is transferred to a discharging aerodynamic chamber 51, a discharging aerodynamic chamber 52, and a discharging lateral movement chamber 53.
The water is transferred to the decontamination device 54 via the decontamination equipment 54. The exhaust air chamber 51 is connected to an exhaust device 55.
It has a sealed structure connected to a He gas supply device 56, and the interior can be switched between a He gas atmosphere and a vacuum atmosphere. A gate valve 57 is interposed between the discharge airlock chamber 51 and the discharge airlock chamber 52. The dispensing airlock chamber 52 has a sealed structure connected to an exhaust device 58 and a N ₂ gas supply device 59, and can be switched between a vacuum atmosphere and an atmospheric atmosphere.

A gate valve 61 is provided between the dispensing airlock chamber 52 and the lateral movement device 53. The lateral movement device 53 is configured to move the fuel element h fed along the fifth line E in parallel to the sixth line F, and send it out along the sixth line F. A gate valve 62 is provided between this lateral movement device 53 and the decontamination device 54.

Note that the filling device 1, the receiving lateral movement device 2,
A receiving airlock chamber 3, a degassing chamber 4, a primary cooling airlock chamber 5, a secondary cooling chamber 6, and passages 63, 6 that communicate the secondary cooling chamber 6 with the welding chamber 33.
4. The discharging airlock chamber 51, discharging airlock chamber 52, and discharging lateral movement device 53 are provided with fuel elements h,
A transfer mechanism (not shown) is provided for holding h' and sending it out or pulling it in the axial direction.

Next, the operation of this embodiment will be explained.

After filling with pellets c, semi-finished fuel elements h' with temporary end plugs d are passed through the first wire A every takt.
The materials are sent out from the filling device 1 along the same direction, and are sequentially introduced into the receiving lateral movement device 2. And this fuel element
The fuel element h' is moved in parallel to the second line B by the lateral movement device 2, and when the gate valve 8 is opened, the fuel element h' is sent out in the axial direction and introduced into the aerodynamic chamber 3 for receiving the atmospheric atmosphere. do. Thereafter, the gate valve 8 is closed and the exhaust device 9 is activated to evacuate the air chamber 3. After the inside of this aerodynamic chamber 3 reaches a vacuum atmosphere similar to that in the degassing chamber 4, the gate valve 11 is opened and the fuel element h' in the aerodynamic chamber 3 is introduced into the degassing chamber 4. do. At this time, the fuel element h' is held in the barrel 14 of the degassing chamber 4 by the cooperation of the transferring mechanism of the aerodynamic chamber 3 and the transferring mechanism of the degassing chamber 4. The barrel 14 holds one fuel element h' per takt time and rotates intermittently in the direction of the arrow. This allows the fuel element
h' moves within the degassing chamber 4 while being heated and degassed for about 3 hours, and reaches the discharge position corresponding to the third passage C. Then, the fuel elements h' that have reached the discharge position are sequentially sent out in the axial direction along the third passage C. That is, fuel element h' is connected to outlet port 1
6, open the gate valve 20,
The fuel element h' is transferred from the degassing chamber 4 to the aerodynamic chamber 5. At this time, the inside of the aerodynamic chamber 5 is kept in a vacuum atmosphere similar to the inside of the degassing chamber 4. After transferring the fuel element h' into the aerodynamic chamber 5, the gate valve 2
0 is closed, the He gas supply device 19 is activated, and the inside of the airlock chamber 5 is heated in the same manner as the secondary cooling chamber 6.
Switch to He gas atmosphere. As a result, the fuel element h' within the airlock chamber 5 is preliminarily cooled. Next, the gate valve 21 is opened and the fuel element h' in the airlock chamber 5 is introduced into the secondary cooling chamber 6. At this time, the fuel element h' is held in the barrel 25 of the secondary cooling chamber 6 by the cooperation of the transfer mechanism of the aerodynamic chamber 5 and the transfer mechanism of the secondary cooling chamber 6. In this way, the fuel element h' introduced into the secondary cooling chamber 6 and stored in the receiving position of the barrel 25 advances for about 2 hours to a position that coincides with the fourth line D located at the orbital welding position. During this time, it is cooled down to a specified temperature. Then, the fuel element h' that has reached the circular welding position is sent out toward the welding chamber 33 along the fourth line D, and circular end plug welding as described later is performed at the circular welding section 34 of this welding chamber 33. When this circular welding is completed, the fuel element h is pulled back into the secondary cooling chamber 6 again and advances to the fifth passage E corresponding to the outlet port 27 and the second outlet port 29 as the barrel 25 rotates. During this period, the circumferentially welded portion is cooled to an appropriate temperature, for example, about 50°C. The fuel element h is fed from this position through the gate valve 32 to the pressure welding section 35 of the welding chamber 33, where pressure welding as described later is performed. When this pressurized welding is completed, the fuel element h is returned to the secondary cooling chamber 6, the gate valve 49 is opened, and the fuel element h is sent into the exhaust air chamber 51 which is in a He gas atmosphere. After the fuel element h is transferred into the aerodynamic chamber 51, the gate valve 49 is closed and the exhaust device 55 is operated to switch the interior of the aerodynamic chamber 51 to a vacuum atmosphere. Thereafter, the gate valve 57 is opened to transfer the fuel element h in the discharge airlock chamber 51 to the discharge airlock chamber 52 which is in a vacuum atmosphere. Then, the gate valve 57 is closed, and the N ₂ gas supply device 59 is operated to supply air in the dispensing aerospace chamber 52.
After performing _N2 gas purge, the atmosphere is changed to atmospheric air.
Open the gate valve 61 and move the dispensing lateral movement device 5
3, the fuel element h is delivered. Then, the lateral movement device 53 changes the line passage and sends the fuel element h to the decontamination device 54.

Here, the aforementioned end plug circumferential welding work will be briefly explained. First, the fuel element h' equipped with the temporary end plug d is advanced from the secondary cooling chamber 6 side to a fixed position and is gripped by the main chuck 36. After that,
The sub-chuck 37 is moved from the standby position toward the fuel element to grasp the temporary end plug d, and in this state, the sub-chuck 37 is returned to the standby position to remove the temporary end plug d from the stainless steel pipe b. Then, the temporary end stopper d is put into the collection box using the hand 43. Furthermore, the hand 43 is operated to mount the spring e into the stainless steel pipe b, and the sub chuck 37 is made to grip the main end plug f. Thereafter, the subchuck 37 is moved toward the fuel element, and the main end plug f is press-fitted into the open end of the stainless steel pipe b. Then, the welding torch 38 is opposed to the joint between the main end plug f and the stainless steel pipe b, and after checking whether the clearance is appropriate, a light shielding mask is set and circular welding is performed. That is, the main chuck 36
While rotating the fuel element h′ around the axis,
The joint g between the end plug f and the stainless steel pipe b is welded airtight over the entire circumference.

In addition, to briefly explain the pressure welding work mentioned above, first, the fuel element h which has been circularly welded is
It is advanced from the next cooling chamber 6 side to a fixed position and gripped by the main chuck 36. Thereafter, the main chuck 39 rotates the fuel element h around its axis to set and fix the welding point k in a fixed position. Then, the pressurization chamber 41 is moved to airtightly enclose the end plug mounting portion of the fuel element h, and a high-pressure (for example, about 30 atmospheres) He gas is contained in the pressurization chamber 41. supply. As a result, the high-pressure He gas in the pressurized chamber 41 is filled into the fuel element h through the small hole m formed in the end plug f. Next, the welding torch 42 is opposed to the welding point k, that is, the open end of the small hole m, and pressure welding is performed after checking the clearance. As a result, the small hole m is closed and the high pressure He gas is sealed within the fuel element h.

As described above, degassing, He replacement, and end plug welding can be performed sequentially, but the end plug welding device comprising the secondary cooling chamber 6 and the welding chamber 33 is different from the conventional one. The difference is that it uses a continuous conveyance method. In addition to the inlet port 26 and the outlet port 27, the cooling chamber 6 has two lead-in/out ports 28 and 29, and a circumferential welding part 34 and a pressure welding part 35 are provided at different positions. The welding process is applied to each part in sequence. Therefore, the conventional constraints of having to stop pressure welding when performing circular welding and stopping circular welding when performing pressure welding are eliminated, and the above-mentioned Circumferential welding section 34
Also, the welding process at the pressure welding section 35 can be continued continuously at all times. Therefore, the takt time can be shortened and the throughput per hour can be significantly increased without any difficulty. In addition, if it is like this, the secondary cooling chamber 6
The welding chamber 33 may be maintained in a constant He gas atmosphere at all times. Therefore, it is difficult for oxygen, moisture, etc. to mix into the He gas to be filled into the fuel element, the He gas is easy to manage, and the amount of He gas consumed can be significantly reduced. Thus, it is possible to produce a fuel element h filled with high-purity He gas with few impurity gas components and moisture.

It should be noted that the shapes of the cooling chamber and the welding chamber are of course not limited to those of the above-mentioned embodiments, and various modifications can be made without departing from the spirit of the present invention.

Further, in the above embodiment, an inlet port and an outlet port are provided on one end wall of the cooling chamber, and the first and second lead-in/out ports are provided on the other end wall. It is not necessarily limited to such a port arrangement.

(f) Effects Since the present invention has the above-described configuration, it is possible to sequentially and continuously perform the processing steps of circular welding, cooling, and pressure welding, thereby shortening the takt time and increasing the throughput. It is possible to provide an end plug welding device for a fuel element that can be easily and effectively increased in size.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining the manufacturing process of a fuel element, and FIG. 2 is a schematic perspective view showing an embodiment of the present invention. 6... Cooling chamber (secondary cooling chamber), 25... Barrel,
26...Inlet port, 27...Outlet port, 28
...First lead-in/out port, 29...Second lead-in/out port, 33...Welding chamber, 34...Orbital welding section, 35
...Pressure welding part, h, h'...Fuel element.

Claims (1)

[Claims] 1 The interior is made into a He gas atmosphere, and the end wall thereof has an inlet port for introducing the fuel element, first and second outlet/input ports provided at mutually different positions, and an outlet port for introducing the fuel element. a barrel disposed within the cooling chamber for receiving a fuel element fed into the cooling chamber through the inlet port and sequentially translating it to a position opposite each of the ports; An end plug welding device comprising: a welding chamber adjacently provided with a circumferential welding part at a portion corresponding to the first lead-in/out port and a pressure welding part provided at a part corresponding to the second lead-out port; When the fuel element held in the barrel reaches the first outlet port and the second outlet port, the fuel element is temporarily drawn out to the circumferential welding part and the pressure welding part through the corresponding ports, respectively. In addition, the separation distance between the first lead-in/outlet port and the second lead-in/out port is set so that the end plug of the fuel element heated by circular welding reaches the pressure welding part. An end plug welding device for a fuel element, characterized in that the temperature is set to a value that allows cooling to an appropriate temperature.