JPS64680B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method and apparatus for manufacturing a fuel element that can be applied to the manufacturing process of fuel elements for nuclear reactors.

(b) Prior art Fuel elements for nuclear reactors, specifically nuclear fuel rods, are
It is manufactured as shown in FIG. That is, first, as shown in FIG. 1a, fuel pellets c such as uranium oxide are filled into a stainless steel pipe b whose one end is airtightly covered with an end plug a. 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 fuel element h is obtained by circularly welding the joint g to the pipe b in an airtight manner. By the way, the conventional manufacturing method of fuel elements involves the above-mentioned degassing and
The He replacement process is carried out in a common chamber. That is, conventional degassed He
In the replacement step, a single chamber is provided in which a barrel can hold about 20 to 30 semi-finished fuel elements h' as shown in FIG. 1b. First, the inside of this chamber is evacuated and then heated to about 300° C. for about 3 hours to degas it.
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.
In addition, after degassing and He substitution processing are performed on the fuel elements in the chamber in this way, the fuel elements are pulled out from the chamber one by one and the shaft end of the fuel element is inserted into the welding chamber. . After replacing the temporary end plug and the final end plug in this welding chamber, circular welding is performed and the welding is drawn into the chamber.
In this way, all the lap welding is completed,
When pressure welding as described later is required, the fuel elements are similarly temporarily pulled out of the chamber one by one and welded. When this work is completed, the interior of the chamber is brought to the atmosphere and all fuel elements in the chamber are taken out to the outside.
In such a degassing He replacement process, the atmosphere inside the chamber changes from atmospheric atmosphere to high vacuum (high temperature) atmosphere to He gas atmosphere every time the 20 to 30 fuel elements described above are processed. (low temperature)
→ Atmospheric atmosphere must be changed in this order. Therefore, it is difficult to obtain a high vacuum state during degassing, and an extremely large capacity is required of the exhaust system. In addition, after degassing treatment, He replacement treatment is performed in the same chamber, so He
There are disadvantages in that oxygen, moisture, etc. are easily mixed into the gas, it is difficult to manage the He gas, and there is also the problem that the amount of He gas consumed is increased. Furthermore, since the gas atmosphere and temperature within a single chamber must be switched sequentially as described above,
Another problem is that it is difficult to increase the throughput without increasing the number of devices.

(c) Purpose The present invention has been made with attention to the above-mentioned circumstances, and it is possible to obtain a high vacuum state for degassing processing without using a high-capacity exhaust device, and , for performing He replacement processing.
It is an object of the present invention to provide a method for manufacturing a fuel element and an apparatus therefor, which can easily manage He gas, consume less He gas, and greatly improve processing capacity.

(d) Structure In order to achieve the above object, the present invention performs a degassing drying process and changing the atmosphere surrounding the fuel element from a vacuum atmosphere to a He gas atmosphere to cool the fuel element after the degassing drying process. The primary cooling process and the pure He
It is characterized in that the secondary cooling process, which involves holding in a gas atmosphere and performing He gas replacement and cooling, is performed separately in different chambers.

Also, when performing these processes separately,
The fuel element is characterized in that the fuel element is continuously conveyed in-line to pass through each of the chambers in sequence.

Furthermore, the device is characterized in that the fuel element is conveyed in the axial direction and sequentially passes through each of the chambers.

(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 substitution 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 is a metal-clad tube having an end plug a hermetically sealed at one end, and a temporary end plug d at the other end of the stainless steel pipe b. The semi-finished fuel element h' produced in this way is sent out along the first line A in the axial direction. 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 translate the fuel element h' fed along the first solid line A to a second line B, and send it out along the second line B. . A second gate valve 8 is provided between the lateral movement device 2 and the first airlock chamber 3. Aerospace room 3 for reception
has a sealed structure connected to an exhaust device 9, and the interior thereof can be switched between an air atmosphere and a vacuum atmosphere. A second 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 each disc 14a
A plurality of holding holes 14b are bored at equal pitches in the circumferential direction near the peripheral edge of the holding hole 14b. One fuel element h' is held in each of the holding holes 14b with matching wires, and rotated intermittently one pitch at a time. The end wall of the sealed container 13 is provided with an introduction 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.
There is a hole. Each time the barrel 14 finishes intermittent rotation, a different holding hole 14b faces the introduction port 15 and the outlet port 16. In addition, this sealed container 13
A heater 17 is disposed inside the barrel 14 to heat the rotating fuel element h' held in the barrel 14. Then, the outlet port 16 of this degassing chamber 4
A gate valve 20 is interposed between the air tank and the second aerodynamic chamber 5. Second aerodynamic chamber 5
It has a sealed structure equipped with an exhaust device 18 and a He gas supply device 19, and the inside is kept in a vacuum atmosphere.
It can be switched between He gas atmosphere and He gas atmosphere. A gate valve 21 is interposed between the aerodynamic chamber 5 and the secondary cooling chamber 6. The secondary cooling chamber 6 is formed in a sealed container 24 connected to an exhaust system 22 and a He gas supply system 23, and houses a barrel 25 for holding a fuel element having a similar configuration to the barrel 14. ing. Note that, on one end wall of the sealed container 24, there is an introduction port 26 that corresponds to the third line C;
A lead-out port 27 corresponding to a fifth line E parallel to the line C is bored, and a first line D corresponding to the fourth line D parallel to the third line C is bored in the other end wall.
A lead-in/out port 28 and a second lead-in/out port 29 corresponding to the fifth line E are provided. The inside of this second cooling chamber 6 is always maintained in a pure He gas atmosphere. That is, this second cooling chamber 6
is sufficiently vented 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. In addition, since the temperature of the He gas may gradually rise in the secondary cooling chamber 6, the temperature inside the chamber is controlled by circulating the He gas and performing forced cooling using a cooler (not shown). is being carried out.

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. For this reason, like the secondary cooling chamber 6 mentioned above, it is necessary to fully exhaust the air before steady operation.
Fill with He 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 at a portion of this welding chamber 33 corresponding to the fourth wire D, and a pressure welding portion 35 is provided at a portion corresponding to the fifth wire E. 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 stainless steel pipe b of the fuel element h' and rotates it around its axis.
a sub-chuck 37 that grips the end plug d (or f) and rotates it 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 mounting portion and a welding torch 42 having a nozzle facing the outer periphery of the end plug f of the 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.

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 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 that communicates 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 airlock chamber 51, a discharging airlock 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 this 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 the lateral movement device 2 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 method for manufacturing a fuel element according to the present invention,
The operation of the manufacturing apparatus described above will be explained.

After the degassing drying process, the atmosphere surrounding the fuel element h′ after the degassing drying process is changed from a vacuum atmosphere to He
A primary cooling process in which the fuel element h' is cooled by switching to a gas atmosphere, and a secondary cooling process in which the fuel element h' after this primary cooling is held in a pure He gas atmosphere for a certain period of time to perform He gas replacement and cooling. The processing is carried out separately in different chambers, that is, the degassing chamber 4, the aerodynamic chamber 5, and the secondary cooling chamber 6. Further, in carrying out these treatments separately, the fuel element h' is continuously conveyed in-line to pass through each of the chambers 4, 5, and 6 in sequence.

Specifically, after filling pellets c, semi-finished fuel elements h' fitted with temporary end plugs d are sent out from the filling device 1 along the first passage A one by one every takt.
They are sequentially introduced into the receiving lateral movement device 2. and,
This fuel element h' is moved in parallel to the second passage 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 to the air chamber 3 for receiving atmospheric atmosphere. to be introduced within. 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 inside the degassing chamber 4, the gate valve 11 is opened and the fuel elements in the aerodynamic chamber 3 are removed.
h' is introduced into the degassing chamber 4. 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 is
One fuel element h' is held per takt time and rotated intermittently in the direction of the arrow. As a result, 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, the gate valve 20 is opened when the fuel element h' faces the outlet port 16, and the fuel element h' is transferred from the degassing chamber 4 to the aerodynamic chamber 5. At this time, the air chamber 5
The inside of the degassing chamber 4 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 20 is closed and the He gas supply device 19 is activated to convert the inside of the aerodynamic chamber 5 into a secondary cooling chamber 6. Switch to a similar He gas atmosphere. As a result, the fuel element h' within the airlock chamber 5 is preliminarily cooled. Next, open the gate valve 21,
The fuel element h' in the aerodynamic chamber 5 is transferred to the secondary cooling chamber 6.
to be introduced within. 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 passage D, which is the circular 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 down to an appropriate temperature. and,
The fuel element h that requires pressure welding 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. and,
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 closed.
is activated in this dispensing airlock chamber 52.
After performing _N2 gas purge, the atmosphere is changed to atmospheric air.
Open the gate valve 69 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 injected 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.

To briefly explain the above-mentioned pressure welding operation, first, the fuel element h which has undergone circumferential welding is advanced from the secondary cooling chamber 6 side to a fixed position and is gripped by the main chuck 36. Thereafter, the fuel element h is rotated around its axis by the action of the main chuck 36, and the welding point k is set and fixed at 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 substitution, and end plug welding can be carried out sequentially, but in the degassing He substitution process corresponding to the first half, unlike the conventional process, degassing drying treatment, The primary cooling process and the secondary cooling process are performed separately in different chambers, that is, the degassing chamber 4, the aerodynamic chamber 5, and the secondary cooling chamber 6. Therefore, the interior of the degassing chamber 4 only needs to be kept at a specified degree of vacuum and temperature at all times, and
The secondary cooling chamber 6 may be maintained in a constant He gas atmosphere at all times. Therefore, the inside of the degassing chamber 4 can be maintained in a high vacuum state using the exhaust device 12 with a relatively small capacity, and also,
Since the temperature is not raised or lowered, heat loss can also be minimized. Furthermore, since He gas replacement is not performed in the degassing chamber, it is difficult for oxygen, moisture, etc. to mix with He gas, making it easy to manage He gas, and significantly reducing He gas consumption. . Thus, it is possible to produce a fuel element h filled with high-purity He gas with few impurity gas components and moisture. With such a device, it is possible to eliminate wasted time for switching the temperature and atmosphere, so that the throughput can be effectively increased without increasing the number of devices. Then, as described above, while continuously conveying the fuel element h' in-line, each of the rooms 4,
5 and 6 in sequence, the processing can be made smoother, and this is particularly effective in increasing the amount of processing.

Furthermore, in the manufacturing apparatus, the elongated fuel element h' is passed through the degassing chamber 4, the aerodynamic chamber 5, and the secondary cooling chamber 6 in sequence while being transferred in the axial direction. 5 and 6 can be reliably isolated using simple closing means such as the aforementioned gate valve or ball valve. Therefore, for example, the seal structure can be simplified compared to the case where the fuel element is transferred in the radial direction.
The manufacturing method described above can be carried out economically.

Note that the invention described in claim 1 includes:
Embodiments are included in which a plurality of fuel elements are sequentially introduced into each chamber.

In addition, the invention described in claim 2 includes:
Embodiments in which the fuel elements are conveyed continuously in the radial direction are also included.

Furthermore, it goes without saying that the structure of the barrel, the shape of the degassing chamber, the aerodynamic chamber, the secondary cooling chamber, etc. are not limited to those of the above embodiments, and can be modified in various ways without departing from the spirit of the present invention. It is.

Further, in the above embodiment, the case where the secondary cooling chamber is provided with an inlet/outlet port for circular welding and an inlet/outlet port for pressure welding is described, but the present invention also applies to a case where pressure welding is not performed. The same applies.

(f) Effect Since the present invention has the above-described configuration, it is possible to obtain a high vacuum state for degassing treatment without using a high-capacity exhaust device, and it is also possible to perform He replacement treatment. It is easy to manage He gas for carrying out, and consumption of He gas is small.
It is possible to provide a method and apparatus for manufacturing a fuel element that can significantly improve processing capacity.

[Brief explanation of drawings]

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. 4... degassing chamber, 5... aerodynamic chamber, 6...
Secondary cooling chamber, 14...barrel, 25...barrel,
h, h'... fuel element, a... end plug, b... metal clad tube (stainless steel pipe), c... fuel pellet,
f...End plug.

Claims (1)

[Claims] 1. Fill a plurality of fuel pellets into a metal clad tube with an end plug attached to one end to form a semi-finished fuel element, and degas the fuel element by heating it in a vacuum atmosphere. After drying, the gas inside is purified.
A method for producing a fuel element, which comprises replacing the metal cladding with He gas and finally sealing the other end of the metal cladding tube with an end plug to obtain a completed fuel element. , a primary cooling process in which the atmosphere surrounding the fuel element after this degassing drying process is switched from a vacuum atmosphere to a He gas atmosphere to cool the fuel element, and a primary cooling process in which the fuel element after this primary cooling is purified for a certain period of time.
1. A method for manufacturing a fuel element, characterized in that secondary cooling treatment in which He gas replacement and cooling are performed while being held in a He gas atmosphere are performed separately in different chambers. 2 A semi-finished fuel element is obtained by filling a metal clad tube with an end plug at one end, and this fuel element is then heated in a vacuum atmosphere and subjected to a degassing drying process. , the gas inside it is purified
A method for manufacturing a fuel element, in which a completed fuel element is obtained by purging the metal cladding tube with He gas, and then airtightly fitting an end plug to the other end of the metal cladding tube, the method comprising: performing the degassing drying process; a primary cooling chamber for cooling the fuel element by switching the atmosphere surrounding the fuel element from a vacuum atmosphere to a He gas atmosphere after this degassing and drying process; and a primary cooling chamber for cooling the fuel element after this primary cooling. Secondary cooling chambers are provided separately for holding the fuel element in a pure He gas atmosphere for a certain period of time to perform He gas replacement and cooling, and the fuel elements are continuously transported in-line to sequentially move through each of the chambers. A method for manufacturing a fuel element, characterized in that the fuel element is allowed to pass through the fuel element. 3. A degassing chamber in which the fuel element is heated under a vacuum atmosphere while being held by a barrel, and a secondary cooling chamber in which the fuel element is cooled in a He gas atmosphere while being held by a barrel are installed inside the fuel element. The fuel elements are connected in series through an aerodynamic chamber which can be switched to a vacuum or a He gas atmosphere while the degassing chamber is housed, and which also serves as a primary cooling chamber for the fuel elements, and are fed out in the axial direction from the degassing chamber. 1. An apparatus for producing a fuel element, characterized in that the fuel element is sequentially supplied to the secondary cooling chamber via the aerodynamic chamber to perform a degassing He replacement process on the fuel element.