JP3088656B2 - Nuclear fuel rod welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a nuclear fuel rod welding apparatus.

[0002]

Generally, a nuclear fuel rod is shown in FIG.
As shown in FIG. 1, a lower end plug 2 is fixed to a lower end of a cladding tube 1, an upper end plug 3 is fixed to an upper end, and a plurality of pellets 4 inserted between both end plugs 2 and 3 are pushed by a spring 5 to end plugs. 2, and the internal space 6 is filled with an inert gas.

In order to manufacture this nuclear fuel rod, first, a lower end plug 2 is fixedly welded to one end of a cladding tube 1, and a required number of pellets 4 and press springs 5 are loaded from the other end. Is replaced with an inert gas, and then the upper end plug 3 is welded and sealed.

FIG. 4 is a view showing a conventional end plug welding apparatus for welding an end plug to the cladding tube 1. As shown in FIG. The welding mechanism 7 has a closed welding chamber 8 for welding and fixing the upper end plug 3 to the cladding tube 1, and the end of the cladding tube 1 is inserted into the welding chamber 8 from one side thereof. It is so.

On the other hand, the end plug 3 is attached to the other side wall of the welding chamber 8 by a chuck 9 of a press shaft.
The end plug 3 is pushed into the opening of the cladding tube 1 by its forward movement. A vacuum exhaust port 10 is formed in the ceiling of the welding chamber 8, and the welding chamber 8 is moved before the welding operation.
After the air is exhausted through the vacuum exhaust port 10, it is filled with an inert gas. A welding torch 11 is further attached to the ceiling of the welding chamber 8. The front end faces the end of the cladding tube 1, and the welding torch 11 welds and fixes them together with the end plug 3 pushed into the cladding tube 1.

[0006] A rotation drive mechanism 12 for the cladding tube 1 is disposed on the side of the welding chamber 8 on the insertion port side of the cladding tube 1, and is provided on the rear end wall of the rotation drive mechanism 12 (the side opposite to the welding chamber 8). Is provided with a seal mechanism 13. The rotation drive mechanism 12 has a spindle 15 rotatably supported by a support mechanism 14 about a horizontal axis. A pulley 16 is provided on the spindle 15, a through hole 17 is formed on the center axis of the spindle 15, and the cover tube 1 inserted in the through hole 17 is gripped at a tip portion. A chuck 18 is provided.

The through hole 1 of the spindle 15
When the cladding tube 1 is inserted into the welding chamber 7 and its tip is inserted until it reaches a predetermined position in the welding chamber 8, the cladding tube 1 is gripped by the chuck 18, and then the spindle 15 is pulled through the pulley 16. Is rotated to rotate the cladding tube 1.

A casing 19 of the rotary seal mechanism 13 is fixed to a rear end wall of the rotary drive mechanism 12. In the casing 19, a cylinder member 22 having a through-hole 20 through which the cladding tube 1 is inserted at the center and a pressing ring 21 concentric with the through-hole 20 slidably in the axial direction is provided. It is arranged rotatably around. A seal ring holding member 23 fixed to the rear end of the spindle 15 is interposed between the cylinder member 22 and the spindle 15.
3, a seal ring 24 is provided between the pressing ring 21 and
Further, the casing 19 has a pressure pipe 26 for supplying pressurized air to a pressure chamber 25 formed at the rear of the press ring 21.
Is connected.

After the nuclear fuel rod cladding tube 1 is inserted into the welding chamber 8 through the through holes 17 and 18 in the rotary seal mechanism 13 and the rotary drive mechanism 12, pressurized air is supplied to the pressure chamber 25 and pressed. By pressing the ring 21, the seal ring 24 is reduced in diameter and its inner peripheral edge is pressed against the outer periphery of the cladding tube 1, so that the outer periphery of the cladding tube 1 is kept airtight.

In the welding of the nuclear fuel rod cladding tube 1 and the end plug 3, a high quality is required for the welded portion because of the use of the nuclear fuel rod. In order to obtain this high quality, the gaps in the welding chamber 8 and the cladding tube 1 must be replaced with a high-purity inert gas. For this purpose, after the air in the welding chamber 8 and the cladding tube 1 is exhausted, the air is replaced with an inert gas. In this case, the higher the degree of vacuum in the welding chamber 8, the higher the purity of the inert gas can be replaced. Consequently, a high quality weld is obtained.

In order to improve the degree of vacuum in the welding chamber 8, the sealing between the welding chamber 8 and the outside must be completely performed. Incompleteness of the process results in insufficient pressure contact between the outer peripheral surface of the cladding tube 1 and the seal ring 24 to prevent a high vacuum from being obtained, or the introduction of air during welding, which adversely affects the welded portion. And the cylinder member 22
Compressed air supplied to the pressure chamber 25 is mixed into the welding chamber 8 via the worn O-ring, and has a disadvantage that the welded portion is adversely affected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a nuclear fuel rod welding installation apparatus which improves the sealing performance between a welding chamber and the outside. is there.

[0013]

According to the present invention, an end plug is press-fitted into a tube end of a nuclear fuel rod cladding tube, and the cladding tube end and the end plug are welded in a welding chamber while rotating the cladding tube. In a nuclear fuel rod welding apparatus, a seal having a U-shaped cross-sectionally deformable hollow annular seal member having an inner diameter equal to or greater than the outer diameter of the cladding tube when no load is applied and having a working fluid introduction hole is provided. The cladding tube is fitted and fitted to the inward flange of the material holding member, and is concentrically clamped at the cladding tube insertion port for inserting and removing the cladding tube end into the welding chamber, concentrically with the cladding tube inserted into the welding chamber. By supplying a working fluid into the hollow portion of the seal material, the inner diameter of the seal material is reduced, and the inner periphery of the seal material is brought into close contact with the outer periphery of the cladding tube for sealing.

[0014]

Preferably, the working fluid is an inert gas.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show the structure of a nuclear fuel rod welding apparatus according to an embodiment of the present invention. Here, the same components as those of the apparatus shown in FIG. The detailed description is omitted.
A substantially cylindrical casing 28 of the rotary seal mechanism 27 is fixed to the rear end face of the support mechanism 14 of the rotary drive mechanism 12. The spindle 15 of the rotary drive mechanism 12 protrudes into the casing 28, and the spindle 15
A sealing material 30 is interposed between the sealing material holding member 29 and the sealing material holding member 29 attached to the tip of the sealing material. That is, the sealing material holding member 29 is attached to the tip of the spindle 15 by the bolt 31 or the like, and is configured to rotate integrally with the spindle 15. The sealing member 30 is a hollow annular member,
It has a U-shaped cross section whose outer peripheral portion is open. 32
Is the hollow part.

On the other hand, a cylindrical seal holding member 33 is interposed between the inner peripheral surface of the casing 28 and the spindle 15 and the seal sandwiching member 29. The seal material holding member 33 is annular, and has an inward flange 34 extending in the circumferential direction on the inner peripheral surface thereof.
4 is fitted into the hollow portion 32 from the outer periphery of the sealing material 30 to prevent the sealing material 30 from coming off,
Is prevented from collapsing in the axial direction, and the mounting state is stabilized. A pressure chamber 35 is formed on the outer periphery of the seal material holding member 33 and extends in the circumferential direction over the entire periphery. The inward flange portion 34 extends from the pressure chamber 35 through the inward flange 34 toward the inner peripheral portion. The hollow portion 32 of the sealing material 30
A gas introduction hole 36 is formed to open at the bottom. The casing 28 is provided with a pressurized gas supply pipe 37 that opens into the pressure chamber 35. Furthermore, casing 2
O-rings 38 to 41 are provided between the inner surface of the seal member 8 and the outer peripheral surface of the seal material holding member 33 and between the inner peripheral surface of the seal material holding member 33 and the outer peripheral surface of the spindle 15.

When the pressurized gas is supplied from the pressurized gas supply pipe 37 to the pressure chamber 35, the pressurized gas is supplied to the hollow portion 32 of the sealing material 30 through the gas introduction hole 36, and thereby the The material 30 expands, and the inner peripheral portion thereof comes into pressure contact with the spindle 15 to exhibit a sealing function (see FIG. 2A). Conversely, when the gas in the seal material 30 is exhausted from the pressurized gas supply pipe 37 through the gas introduction hole 36, the seal material 30 returns to its original shape (see FIG. 2B).

When the cladding tube 1 and the end plug 3 are to be welded by the apparatus configured as described above, first, one end plug 2 is welded.
In a state where the pellet 4 and the pressing spring 5 are loaded into the cladding tube 1 in which is welded, the cladding tube 1 is inserted into the through hole so that the end of the cladding tube 1 on the side where the other end plug 3 is mounted enters the chamber 8. insert. Next, an inert gas is introduced into the sealing material 30 through the pressurized gas supply pipe 37 and expanded to reduce the inner diameter of the sealing material 30 to thereby seal the welding chamber 8 from the outside. Then, the inside of the welding chamber 8 is filled with an inert gas through the vacuum exhaust port 10, and the space 6 in the cladding tube 1 is filled.
At the same time with an inert gas and prepare the welding environment. Subsequently, the end plug 3 previously loaded on the chuck 9 of the press shaft is inserted into the open end of the cladding tube 1 by the press shaft. Furthermore, the cladding tube 1 is rotated by the action of the rotation drive mechanism 12 and the welding torch 11 is operated in that state, whereby the cladding tube 1 and the end plug 3 are welded.

As described above, according to the present embodiment, the sealing material 30 is expanded by the gas pressure, and the sealing material 30 is brought into contact with the outer periphery of the cladding tube 1 by the expansion action. Even if the shape of the cross-sectional shape is somewhat poor, a good contact state between the sealing material 30 and the outer periphery of the cladding tube 1 can be obtained, and the sealing property is improved.

In addition, no wrinkles are formed on the seal member 30. From this point, a good contact state between the seal member 30 and the outer periphery of the cladding tube 1 is obtained, and the sealing property is improved.

Furthermore, since the contact state between the sealing material 30 and the outer periphery of the cladding tube 1 can be controlled by the atmospheric pressure, the sealing performance can be improved from this point as well.

The use of the same inert gas as the welding shield gas introduced into the welding chamber 8 as the working fluid of the sealing material 30 prevents the deterioration of welding quality due to leakage of the working fluid. .

[0024]

As described above, according to the present invention, the sealing material is expanded by the pressure of the working fluid, and the sealing material is brought into contact with the outer periphery of the cladding tube by the expansion action. Even if the cross-sectional shape is somewhat poor, a good contact state between the sealing material and the outer periphery of the cladding tube can be obtained, and the sealing performance can be improved.

In addition, no wrinkles are formed on the sealing material. From this point, a good contact state between the sealing material and the outer periphery of the cladding tube is obtained, and the sealing property is improved.

Further, the state of contact between the sealing material and the outer periphery of the cladding tube can be controlled by the pressure of the working fluid.
From this point, the sealing performance can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a nuclear fuel rod welding apparatus according to one embodiment of the present invention.

FIGS. 2A and 2B are enlarged views of a main part when the sealing material shown in FIG. 1 is operated, and FIG.

FIG. 3 is a sectional view showing the structure of a nuclear fuel rod.

FIG. 4 is a sectional view showing the structure of a conventional nuclear fuel rod welding apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Clad tube 2 Lower end plug 3 Upper end plug 4 Pellet 5 Push spring 6 Internal gap 7 Welding mechanism 8 Welding chamber 9 End plug chuck 10 Exhaust port 11 Welding torch 12 Rotary drive mechanism 14 Support mechanism 15 Spindle 16 Pulley 17 Through hole 18 Cladding tube chuck 27 Rotary sealing mechanism 28 Casing 29 Sealing material holding member 30 Sealing material 31 Bolt 32 Hollow part 33 Sealing material holding member 34 Inward flange 35 Pressure chamber 36 Gas introduction hole 37 Pressurized gas supply pipe

Continuing on the front page (72) Inventor Tomoaki Kume 2-3-1, Kawaguchi, Yokosuka City, Kanagawa Prefecture Inside Nihonkuri Fuyueru Co., Ltd. (72) Toshiyuki Kano 2-3-1, Kawaguchi, Yokosuka City, Kanagawa Prefecture No. Nihonkuria Fuyuru Co., Ltd. (56) References JP-A-3-226379 (JP, A) JP-A-7-60447 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) G21C 21/02 G21C 3/10

Claims (2)

(57) [Claims] 1. An end plug is press-fitted into a tube end of a nuclear fuel rod cladding tube,
In the nuclear fuel rod welding apparatus for welding by welding chamber the cladding tube end while rotating and the said end plug and cladding tube, Mumake
When loaded, it has an inner diameter greater than the outer diameter of the cladding tube, and the outer periphery is open
A hollow ring-shaped sealing material with a U-shaped cross section
Inward franc of seal material holding member having introduction hole for dynamic fluid
And fitting attached to di-, the cladding tube insertion opening for inserting and removing the cladding tube end portion in the welding chamber, held by and cladding tube and concentric to be inserted into the welding chamber, the hollow portion of the sealing material A nuclear fuel rod welding apparatus characterized in that an inner diameter of the seal member is reduced by supplying a working fluid to the inner wall of the seal member, and an inner periphery of the seal member is brought into close contact with an outer periphery of the cladding tube for sealing. 2. The nuclear fuel rod welding apparatus according to claim 1, wherein the working fluid is an inert gas.