JPH0477878B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a system for manufacturing 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 fuel element h is obtained by circularly welding the joint g to the pipe b in an airtight manner.
By the way, the above-described degassing, He substitution, and end plug welding processes have conventionally been performed using a batch type device. That is, the conventional fuel tank has a single chamber in which about 20 to 30 semi-finished fuel elements h' as shown in FIG. 1B can be held by a barrel. First, the inside of this chamber is evacuated and then heated to about 300° C. for about 3 hours to degas it. That is, the moisture contained in the pellets c and the stainless steel pipe b is removed. 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 welding cycles are completed, but if 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 made to have an atmospheric atmosphere, and all fuel elements in the chamber are transferred to a decontamination chamber, decontaminated, and then taken out to the outside. Thereafter, one lot of fuel elements is placed in a special test chamber equipped with a leak test device, and the chamber is evacuated to perform a leak test.

However, with such a manufacturing system,
Each time the fuel elements are removed from the chamber containing the fuel elements before and after end plug welding, the atmosphere in the chamber must be changed from a He gas atmosphere to an atmospheric atmosphere. Therefore, inside the chamber
It is difficult to control the purity of He gas to a high value,
Another problem is that the amount of He gas consumed increases. Moreover, the fuel element with the end plug welded is once introduced into the atmosphere and then introduced into the test chamber, and the chamber is evacuated to a high vacuum state to perform a leakage test. There are questions that require time on the exam. That is, the test chamber is set to the atmospheric atmosphere when receiving the fuel element, and after receiving the test chamber, the exhaust device is activated to exhaust the fuel element to a high vacuum atmosphere. Therefore, even if a very large exhaust system is used, it takes a considerable amount of time to perform a leakage test, resulting in a problem of wasted time and power. In addition, with conventional systems, leakage tests are performed by putting one lot, or 20 to 30 fuel elements, into a test chamber at once, making it impossible to obtain individual data for each fuel element. There is a drawback.
However, if a leakage test is specifically performed on each fuel element in the conventional system, there is a problem in that the loss of time, exhaust power, etc. increases further.

(c) Purpose The present invention has been made in view of the above-mentioned circumstances, and it is possible to maintain a constant atmosphere inside the chamber that accommodates the fuel element after welding the end plug, thereby making it possible to manage He gas, etc. The purpose of the present invention is to provide a manufacturing system for nuclear reactor fuel elements that is easy to perform and that allows highly accurate leak tests to be performed on each fuel element without wasting time or power. shall be.

(d) Configuration In order to achieve the above object, the present invention
The fuel element after end plug welding, which is housed in a chamber with a gas atmosphere, is sequentially moved into a front-stage aero chamber that can be switched from a He gas atmosphere to a vacuum atmosphere, and a rear-stage aero chamber that can be switched from a vacuum atmosphere to an air atmosphere. The system is structured so that the air bubbles are guided out of the chamber one by one through the air chamber, and an intermediate air chamber which is constantly maintained in a vacuum atmosphere is interposed between the two air chambers.
It is characterized by being equipped with a He gas leak test device.

(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 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 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 chamber 13 connected to the exhaust device 12, and houses a barrel 14 for holding a fuel element therein. The barrel 14 is made by connecting a plurality of disks 14a with their axes aligned together, and a plurality of holding holes 14b are bored at equal pitches in the circumferential direction near the periphery of each disk 14a. be. 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 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 are bored in the end wall of the chamber 13. . Then, each time the barrel 14 finishes intermittent rotation, a different holding hole 14b is inserted into the introduction port 15.
and facing the outlet port 16. Further, a heater 17 is disposed within the chamber 13 for heating the fuel element h' which 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 room 6
A barrel 25 for holding a fuel element having the same structure as the barrel 14 is housed inside a chamber 24 connected to an exhaust device 22 and a He gas supply device 23. Note that the chamber 2
4, there is an introduction port 26 that corresponds to the third line C, and a fifth line parallel to the third line C.
A lead-out port 27 corresponding to the wire E is bored, and a first lead-in/out port 28 corresponding to the fourth wire D parallel to the third wire C is provided on the other end wall.
and a second lead-in/out port 29 corresponding to the fifth line E are bored. The inside of this second cooling chamber 6 is always maintained in a He gas atmosphere. That is, the second 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 in this secondary cooling chamber 6, the temperature of the He gas may gradually rise, 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 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) of 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 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 the front stage aero chamber 50, the intermediate aero chamber 51, the rear stage aero chamber 52 and the dispensing lateral movement chamber 53. The water is transferred to the decontamination device 54 via the decontamination equipment 54. Air discharge chamber 50
has a sealed structure connected to an exhaust device 55 and a He gas supply device 56, and the interior thereof can be switched between a He gas atmosphere and a vacuum atmosphere. And this front stage side aerodynamic chamber 5
A gate valve 57 is interposed between 0 and the intermediate airlock chamber 51. Intermediate air chamber 51
is an elongated chamber with a sealed structure, and the chamber 51
A leak test device 59 is attached to the. The leakage test device 59 includes an exhaust system for highly evacuating the inside of the intermediate aerodynamic chamber 51, and an exhaust system that is guided from the intermediate aerodynamic chamber 51 through the exhaust system.
It is equipped with a mass spectrometer for detecting He gas, and is designed to test whether or not the He gas filled in the fuel element h introduced into the intermediate airlock chamber 51 has leaked. This intermediate airlock chamber 51 and the rear airlock chamber 52
A gate valve 61 is provided between the two. The rear air chamber 52 has a sealed structure connected to an exhaust device 62 and a N ₂ gas supply device 63, and can be switched between a vacuum atmosphere and an atmospheric atmosphere. A gate valve 64 is provided between this rear-stage airlock chamber 52 and the lateral movement device 53. Lateral movement device 53
is the fuel element h fed along the fifth line E
is configured to move in parallel to the sixth line F and send it out along the sixth line F. and,
A gate valve 65 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 air chambers 50, 51, 52 and the dispensing lateral movement device 53 are provided with a transfer mechanism (for pinching the fuel elements h, h' by a pinch roller and a drive roller and feeding or retracting them in the axial direction). (not shown) are provided respectively.

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 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 fuel element h' is connected to the 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 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 circumferential welding is completed, the fuel element h is pulled back into the secondary cooling chamber 6 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. Then, the fuel element h that requires pressure welding is passed from this position through the gate valve 32 to the pressure welding part 35 of the welding chamber 33.
, and then pressure welding is performed as described below. When this pressure welding is completed, the fuel element h
The gas is returned to the secondary cooling chamber 6, the gate valve 49 is opened, and the gas is sent into the front-stage aerodynamic chamber 50, which has a He gas atmosphere. After the fuel element h is transferred into the aerodynamic chamber 50, the gate valve 49 is closed and the exhaust device 5
5 is activated to switch the inside of the airlock chamber 50 to a vacuum atmosphere. Thereafter, the gate valve 57 is opened to transfer the fuel element h in the preceding stage aerodynamic chamber 50 to the intermediate aerodynamic chamber 51 which is constantly maintained in a high vacuum atmosphere. Then, the gate valve 57 is closed, and a leakage test is performed on the fuel element h in the intermediate air chamber 51.
That is, if the He gas sealed in the fuel element h leaks into the intermediate airlock chamber 51, the He gas will be detected by the mass spectrometer of the leak test device 59, and the fuel element h
An indication or record is made that the product is defective. Thereafter, the gate valve 61 is opened to transfer the fuel element h in the intermediate airlock chamber 51 to the rear side airlock chamber 52 which is in a vacuum atmosphere. Then, the gate valve 61 is closed,
After activating the N ₂ gas supply device 63 to purge the air chamber 52 with N ₂ gas, the atmosphere is set to atmospheric, and the gate valve 64 is opened to send the fuel element h to the dispensing lateral movement device 53. 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 then advanced from the cooling chamber 6 side to a fixed position and gripped by the main chuck 39. 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 substitution, and end plug welding can be performed sequentially. In this system, the fuel element h after end plug welding housed in the chamber 24 in the He gas atmosphere is The gas is led out of the chamber 24 one by one through a front air chamber 50 that can be switched from a gas atmosphere to a vacuum atmosphere and a rear air chamber 52 that can be switched from a vacuum atmosphere to an air atmosphere. . Therefore, it is possible to always maintain the atmosphere inside this chamber 24 as a He gas atmosphere, making it easier to manage He gas, and
Gas consumption can also be reduced. Moreover, an intermediate airlock chamber 51 is provided between the front airlock chamber 50 and the rear airlock chamber 52, and a leak test device 59 attached to the intermediate airlock chamber 51 allows the fuel to pass through the intermediate airlock chamber 51. Since the element h is subjected to the leakage test sequentially, a highly accurate leakage test can be performed efficiently. In other words, since the intermediate air chamber 51 provided at the position described above can always maintain a vacuum atmosphere inside, it is possible to maintain the high vacuum state necessary for the leak test by using a large-capacity exhaust device. It can be secured without any problems. Therefore, compared to the case where a leakage test is performed by reintroducing a fuel element that has been taken out into the atmosphere into the test chamber, time and energy required for exhaust can be significantly saved. Also,
According to this system, it is possible to perform a special leak test on each fuel element h as it is sequentially taken out from the chamber 24 to the outside, so that more detailed leak tests can be carried out without reducing efficiency. Another advantage is that test data can be obtained.

In the above embodiments, the case where the fuel element is conveyed in the axial direction has been described, but the present invention is not limited to such a system, and can also be applied to, for example, a system in which the fuel element is conveyed in the radial direction. The same applies. However, according to the axial conveyance method, the chambers and airlock chambers can be reliably isolated using simple closing means such as the aforementioned gate valves and ball valves, so the seal structure can be simplified. can.

Further, it goes without saying that the shape and structure of the chamber and the airlock chamber are not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention.

(f) Effects Since the present invention has the above-described configuration, it is possible to maintain a constant atmosphere inside the chamber that accommodates the fuel element after welding the end plug, making it easy to manage He gas, etc. In addition, it is possible to provide a manufacturing system for nuclear reactor fuel elements that can perform an extremely highly accurate leak test on each fuel element without wasting time or power.

[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. 24...Chamber, 50...Previous stage side aerodynamic chamber,
51... Intermediate airlock chamber, 52... Rear stage side airlock chamber, 59... Leak test device, h, h'... Fuel element.

Claims (1)

[Claims] 1 The fuel element after end plug welding, which is housed in a chamber in a He gas atmosphere, is provided with a front-stage aero chamber that can be switched from a He gas atmosphere to a vacuum atmosphere, and a rear-stage aero chamber that can be switched from a vacuum atmosphere to an air atmosphere. This is a manufacturing system for a fuel element configured to sequentially pass fuel elements and lead them out of the chamber one by one, in which an intermediate airlock chamber that is constantly maintained in a vacuum atmosphere is interposed between the two airlock chambers, and the intermediate airlock chamber is A manufacturing system for nuclear reactor fuel elements, characterized in that a chamber is equipped with a He gas leak test device.