JP2502126B2 - Pellet loading device - Google Patents

Description

TECHNICAL FIELD The present invention mainly relates to a pellet loading device for smoothly inserting a nuclear fuel pellet (hereinafter referred to as a pellet) on a pellet tray into a cladding tube of a fuel rod. .

[Conventional technology]

Conventionally, when the pellets on the pellet tray are inserted into the cladding tube of the fuel rod, first, the pellet tray with the pellets placed is placed on the pellet tray holding table, and the space between the pellet tray and the cladding tube is set. Position the pellet guide on the pellet tray, and then insert the cladding tube from one side of the guide hole made in this pellet guide to position the cladding tube, and then push the pellet on the pellet tray by hand. Using a tool, an operator manually pushes the pellet guide from the other side of the guide hole through the pellet guide into the cladding tube.

[Problems to be Solved by the Invention]

However, when the pellets are inserted into the cladding tube by relying on manual labor as in the above-mentioned conventional method, the cladding tube is long (for example, about 4 m). The frictional force with and the like increases the force required to push the pellet in,
The maximum number of pellets that can be inserted into the cladding tube is 8 at a time, the workability is poor, and it is extremely inefficient, and it is difficult to detect abnormal conditions such as pellet clogging quickly and reliably. In some cases, it could not be denied that a large number of pellets placed in a line on the pellet tray may be scattered and fall apart due to delay in noticing the abnormal state.

The present invention has been made in view of the above circumstances, and an object thereof is to allow a pellet to be smoothly and surely inserted into a cladding tube of a fuel rod, and further, an abnormal condition such as pellet clogging. Can be quickly detected,
It is an object of the present invention to provide an extremely efficient pellet loading device which can immediately stop the insertion of the pellets into the cladding tube for the abnormal row and can push the pellets into a large number of cladding tubes at the same time.

[Means for solving the problem]

In order to achieve the above-mentioned object, a pellet loading device according to the present invention is provided with a plurality of pellet guide rods provided at the tip of a pellet tray and for guiding a row of pellets placed on the pellet tray. A plurality of guide tubes provided on the tip side of the pellet guide rod and having a slit in the longitudinal direction and for inserting and guiding the pellet row therein, and provided between the pellet guide rod and the guide tube, and the pellet The pellet guide that guides the guide tube into the guide tube, the guide tube and the coating tube in a straight line, and the pellet / rod guide that guides the pellets in these guide tubes into the coating tube and the pellet row on the pellet tray. Pellet guide rods, pellet guides, and guide tubes with pellet pushers provided for each pellet row And a pellet pressing / transporting mechanism that pushes each into the cladding tube via the pellet / rod guide and the pellet pressing / transporting mechanism.When each pellet pressing tool pushes out the pellet row, the pellet pressing tool that is overloaded is pressed. And an overload prevention mechanism for separating the transfer mechanism from the transfer mechanism.

The detachment of the pellet pusher means a state in which the pellet pusher is released from the engagement state with the pellet pressing / transporting mechanism and the force for pushing the pellet is not transmitted.

In addition, the overload prevention mechanism may be provided with an overload value adjustment mechanism that adjusts the magnitude of the overload that causes the pellet pusher to disengage.

[Action]

In the pellet loading device of the present invention, the pellet pusher of the pellet pressing / transporting mechanism causes the pellets arranged in a row on the pellet tray to pass through the pellet guide rod, the pellet guide, the guide tube, and the pellet / rod guide. While the pellets are inserted into the coating tube and each pellet is supported and transferred between the pellet guide rods, fine powder and the like attached to the pellets are dropped and removed from between the pellet guide rods, while the pellets are removed. When the pusher is overloaded, the overload prevention mechanism stops part of the overloaded pellet pusher from automatically separating from the pellet press transfer mechanism and pushing out the pellet row. The pellet pusher pushes and inserts the pellet rows into the cladding tube by the pellet pushing and transferring mechanism. Moreover, each pellet row passes through the guide tube located immediately before the cladding tube,
Even if the pellet is caught and the insertion force of the pellet pushing tool is suddenly increased, it is possible to prevent the pellet from scattering and falling apart.

In addition, when inserting the pellet into a long cladding tube,
Since the load for pellet insertion will gradually increase as the number of pellets inserted increases, the size of the overload at which the pellet pusher disengages increases with the increase in the number of pellets inserted. By setting the overload value as needed, it is possible to achieve smooth insertion of pellets and prevention of pellet breakage or scattering due to overload at the same time.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

1 to 4 show an example of the pellet loading device of the present invention. FIG. 1 is a perspective view showing the entire structure, FIG. 2 is a sectional view, FIG. 3 is a plan view, and FIG. It is an exploded perspective view of an overload prevention mechanism part. This pellet loading device includes a pellet tray T on which pellets P are placed.
And a plurality of pellet guide rods provided at the tip of the pellet tray T on the pellet tray holder 1 and supported by a pellet guide rod support mechanism 2 to guide the pellets P. 3 and
A pellet guide 4 provided at the tip of these pellet guide rods 3, a pellet rod guide 5 arranged on the tip side of the pellet guide 4 with a predetermined gap, and these pellet guide 4 and pellet rod. Guide 5
Insert both ends into each guide hole 4a, 5a of
In addition, a plurality of guide tubes 6 having a length capable of accommodating at least all the pellets P arranged in a row placed on the pellet tray T, the pellet guide 4, the pellet / rod guide 5, and the guide tube 6 are integrally formed. And a guide body moving mechanism (horizontal cylinder) 7 provided at the base of the guide body G and configured to move the guide body G in the longitudinal direction of the guide tube 6, and a guide hole for the pellet / rod guide 5. Fuel rod pressing jig 8 for pressing and fixing the cladding tube C of the fuel rod inserted at the tip of 5a
And a pellet pressing mechanism 9 provided so as to be retractable from above in the middle portion of the guide hole 5a of the pellet rod guide 5 into which the guide tube 6 and the covering tube C are inserted from both ends.
And the pellet P on the pellet tray T by the pellet pushing tool 10a, the pellet guide rod 3, the pellet guide 4, the guide tube 6, and the pellet / rod guide 5.
A pellet pressing transfer mechanism 10 for pushing the fuel into the cladding tube C of the fuel rod through the pellet pressing transfer mechanism 10 and the pellet pressing tool 10a provided in the pellet pressing transfer mechanism 10 and pushing the pellet P into the pellet pressing tool 10a. It is mainly composed of an overload preventing mechanism 11 for separating the pellet pushing tool 10a when an overload is applied.

The pellet trays T that are left stationary on the pellet tray holding table 1 have a plurality of rows (25 rows in this embodiment) of V grooves.
Ta is formed and V leg Tb is attached to the lower surface. Both ends of the pellet guide rod 3 supported by the pellet guide rod support mechanism 2 are formed with a reduced diameter. Then, this pellet guide rod support mechanism 2
Is attached to the upper end of the piston rod of the lifting cylinder 2a, a pellet guide rod receiver 2b is inserted into the pellet guide rod receiver 2b from below, and a head-supporting pin 2c is slidably inserted. The upper end of is fitted into the pellet guide rod 3 and a spring 2d is mounted between the pellet guide rod 3 and the pellet guide rod receiver 2b and around the headed support pin 2c. Is.

In the guide hole 4a of the pellet guide 4, the opening on the side of the pellet guide rod 3 is formed in a tapered shape to facilitate the insertion of the pellet P, and a slit 4b is formed in the upper portion. Both openings of the guide hole 5a of the pellet / rod guide 5 are tapered so that the pellet P and the cladding tube C of the fuel rod can be inserted easily. Further, a slit 6a is formed on the upper portion of the guide tube 6 in the longitudinal direction thereof. Then, the V groove Ta of the pellet tray T on the pellet tray holding table 1, a pellet flow channel groove 3a constituted by two adjacent pellet guide rods 3, a guide hole 4a of the pellet guide 4, and a guide The tube 6, the guide hole 5a of the pellet / rod guide 5, and the cladding tube C of the fuel rod inserted into the guide hole 5a are installed so as to be aligned in the same straight line.

The pellet pressing mechanism 9 has a urethane rubber pellet pressing mechanism at the lower ends of the piston rods of a pair of pressing cylinders 9a arranged above the pellet rod guide 5.
9b is attached, and the pellet holder 9b is fitted into the guide hole of the pellet / rod guide 5 by the holding cylinder 9a.
It projects from above in the middle of 5a.

Further, the pellet pressing and transferring mechanism 10 is provided on each of the pellet tray holding table 1, the pellet guide rod 3, the pellet guide 4, the guide tube 6 and the pellet / rod guide 5 on the respective bases 10b arranged on both sides thereof. A pair of brackets 10c are provided with a predetermined distance therebetween, and a rotatable ball screw shaft 10d is provided between each pair of brackets 10c.
And the guide rails 10e are arranged in parallel to the transfer direction of the pellets P, and one of the brackets 10c is provided.
A drive motor 10f for rotating the ball screw shaft 10d is attached to the moving table 10g screwed to both ball screw shafts 10d and fitted to both guide rails 10e, the pellet tray holding table 1 and the pellet guide rod. 3, the pellet guide 4, the guide tube 6 and the pellet / rod guide 5 are passed over the above, while the plurality of pellet pushers 10a are attached to the pellets P on the moving base 10g.
Are provided directly above the transfer direction of the. Further, as shown in FIG. 4, each pellet pushing tool 10a has a hanging portion 10i vertically provided at a lower portion of a rod-shaped pushing tool body 10h, and a tip portion (front portion) of this hanging portion 10i.
A pellet pressing portion 10j is formed on the. On the other hand, a plurality of keyhole-shaped grooves 10k for mounting the pusher main body 10h and the hanging portion 10i of the pellet pusher 10a movably in the transfer direction of the pellet P are formed on the lower surface of the moving table 10g. By inserting the pushing tool body 10h and the hanging portion 10i into these groove portions 10k, the pellet pushing tool 1 can be obtained.
0a is suspended on a moving table 10g.

Further, the overload prevention mechanism 11 is formed with a screw hole 10m in a state of being communicated with each other through the small-diameter communication hole 10l above each groove portion 10k of the movable table 10g, and the screw hole 10m has a collar at the middle portion. A lock pin 11b having a portion 11a is fitted therein, and the lower portion of the collar portion 11a of the lock pin 11b is connected to the communication hole 10l.
Projecting downward from the pellet pressing tool 10a and engaging with a U-shaped groove 10n formed in the upper part of the pressing tool body 10h of the pellet pressing tool 10a, while a tightening nut 11c is screwed into the screw hole 10m,
Between the collar portion 11a of the lock pin 11b and the tightening nut 11c and around the lock pin 11b, the spring 1
1d is attached. Then, the tightening nut 11
In c, when a pellet P on one pellet tray T is accommodated in the cladding tube C of the fuel rod by the pellet pressing transfer mechanism 10, the tightening nut 11c is tightened at a predetermined angle to lock the lock pin 11b and the pellet. Nut rotation adjustment mechanism 12 (overload value adjustment mechanism) for strengthening the engagement state with the pusher 10a
Is provided. This allows the pellet pusher to
When a force exceeding the biasing force of the spring 11d is applied to the pellet pressing portion 10j of the spring 10a, the lock pin 11b moves the spring 11d.
The lock pin 11b is disengaged from the U-shaped groove 10n of the pellet pushing tool 10a, and thus the pellet pushing tool 10a moves along the groove 10k of the moving table 10g. It is configured to be movable.

Next, a case will be described where the pellet loading device configured as described above is used to fill the pellets P on the pellet tray T into the cladding tubes C of the fuel rods.

First, as shown in FIG. 1, the pellet tray holding table 1
The pellet tray T is placed on the pellet tray T, and the pellets P are arranged in 25 rows of V grooves Ta at equal intervals on the pellet tray T.
In addition, the moving table 10g is positioned on the base end side of the pellet tray T, and the cladding tube C of the empty fuel rod is inserted into the tip end side of the guide hole 5a of the pellet rod guide 5, while the lifting cylinder 2a and the horizontal The cylinder 7 covers the pellets P on the pellet tray T, the pellet channel 3a between the pellet guide rods 3, the guide hole 4a of the pellet guide 4, the guide tube 6, the guide hole 5a of the pellet / rod guide 5, and the fuel rod. In a state where the pipes C are arranged in a straight line, each ball screw shaft 10d is rotated by the drive motor 10f of the pellet pressing / transferring mechanism 10 so that the moving base 10g screwed to these ball screw shafts 10d is moved to the guide rail 10e. Move forward along. As a result, by advancing the pellet pressing part 10j of the pellet pressing tool 10a in the state of being suspended and inserted in the groove 10k on the lower surface of the moving table 10g,
The pellet pressing portion 10j comes into contact with the rear end surface of the pellets P in the aligned state on the pellet tray T to press and transfer the pellets P forward.

Then, the pellet pusher 10a of the moving table 10g reaches the tip of the guide tube 6 from above the pellet tray T, through the slit 4b in the upper part of the pellet guide 4, and through the slit 6a of the guide tube 6. The pellet P pressed and transferred by the pellet pusher 10a passes through the guide hole 4a of the pellet guide 4, the guide tube 6 and the guide hole 5a of the pellet / rod guide 5 from above the pellet tray T, and It is inserted into the cladding tube C.

Next, when all the pellets P on one pellet tray T are transferred to the cladding tube C side of the fuel rod, the drive motor 10
Reversely rotate f to move the moving table 10g back to the original position, and place a new pellet tray T on the pellet tray holding table 1 instead of the empty pellet tray T. Repeat the operation until the pellet pusher 10
The pellet P on the pellet tray T is pushed into the cladding tube C of the fuel rod by a.

In this case, as the number of pellets P inserted into the cladding tube C of the fuel rod increases, the weight of the pellet and the frictional force between the pellet P and the cladding tube C increase, so the pellet P is inserted. The insertion force required for this purpose increases, but each time the pellet tray T on the pellet tray holding base 1 is replaced, the nut rotation adjusting mechanism 12 rotates the tightening nut 11c to increase the tightening and lock. Pin 1
By increasing the engagement state between the 1b and the U-shaped groove 10n of the pellet pressing tool 10a, the pellet P can be smoothly and surely formed.
Can be inserted into the cladding tube C of the fuel rod.

Further, the fine powder or the like adhering to the pellets P being transferred falls downward from between the pellet guide rods 3 when the pellets P pass through the pellet flow channel 3a constituted by the pellet guide rods 3. Therefore, it is not carried into the cladding tube C of the fuel rod.

Furthermore, when the pellet P is inserted into the cladding tube C of the fuel rod by the pellet pusher 10a, the pellet P should be
When the insertion force of the pellet pusher 10a is suddenly increased due to the lock pin 11b, the lock pin 11b engaged with the U-shaped groove 10n of the pusher body 10h of the pellet pusher 10a is locked by the spring 11.
Withdrawing upward against the urging force of d, thereby releasing the engagement state between the two, as the moving table 10g advances, only the pellet pusher 10a released from the engagement state,
It stops at that position, and therefore moves backward relative to the movable table 10g along the groove 10k of the movable table 10g. As a result, only the pellets P in the row in which the pellets P are caught are
The pressing by the pellet pressing tool 10a is stopped, and the pellets P in the other rows are pressed smoothly and the transfer is continued.

Furthermore, even if the pellet P is caught and the insertion force of the pellet pusher 10a is rapidly increased, the pellet P is still contained in the guide tube 6 and is transferred. Therefore, the pellets P do not fall apart and scatter upwards, and the aligned state of the pellets P does not collapse.

In this manner, the pellets P on the pellet tray T are sequentially inserted into the cladding tube C of the fuel rod, and the cladding tube C
When the pellets P have been filled inside, the pellet presser cylinder 9a lowers the pellet presser 9b to remove the pellet P half inserted into the cover tube C, and the pellet presser 9b allows the inside of the cover tube C to be removed. The pellet P protruding from the top is pressed down from above. Next, in this state, after the pellet guide rod 3 is lowered by the elevating cylinder 2a, the guide body G is retracted by the horizontal cylinder 7 (to the right in FIG. 2). As a result, the cladding pipe C of the fuel rod inserted into the tip end side of the guide hole 5a of the pellet / rod guide 5 is smoothly pulled out from the guide hole 5a, and the pellet P in a state of partially protruding from the inside of the cladding pipe C. Is pressed by the pellet retainer 9b, and thus remains on the guide body G side and retracts together with the guide body G. Therefore, the cladding tube C of the fuel rod is filled with a predetermined number of pellets P.

Subsequently, a new empty fuel rod cladding tube C is installed in place of the fuel rod cladding tube C that has been filled with the pellets P, and then the horizontal cylinder 7 and the lifting cylinder 2a are installed.
Are sequentially operated to move the guide body G forward (to the left in FIG. 2) toward the cladding tube C side of the fuel rod, and then the pellet guide rod 3 is lifted to return to the initial state, and the pellet P is again pressed. Is started in the cladding tube C of the fuel rod.

〔The invention's effect〕

As described above, the present invention is provided at the tip portion of the pellet tray, a plurality of pellet guide rods for guiding pellets, and provided at the tip side of these pellet guide rods,
A plurality of guide tubes that have slits in the longitudinal direction and that insert and guide a pellet row inside, a pellet guide that is provided between the pellet guide rod and the guide tube, and guides the pellet into the guide tube, and a guide tube Pellets and rod guides that linearly support the and the coating tubes and guide the pellets in these guide tubes into the coating tubes, and the pellet row on the pellet tray by the pellet pusher provided for each pellet row. Guide rods, pellet guides, guide tubes and pellets
Pellet pressing transfer mechanism that pushes each into the coating tube via the rod guide, and when each pellet pressing tool pushes out the pellet row, the pellet pressing tool that is overloaded is pushed from the pellet pressing transfer mechanism. Since it is equipped with an overload prevention mechanism for releasing it, the pellet pushing tool allows the pellets arranged in a row on the pellet tray to be passed through the pellet guide rod, pellet guide, guide tube and pellet / rod guide. While the pellets are inserted into the coating tube and each pellet is supported and transferred between the pellet guide rods, fine powder and the like attached to the pellets are dropped and removed from between the pellet guide rods, while the pellets are removed. When the pusher is overloaded, the overload prevention mechanism causes some of the pellet pushers that are overloaded. Although it automatically disengages from the pellet press transfer mechanism and stops pushing the pellets, the remaining pellet pusher can be continuously inserted into the cladding tube without interrupting the extrusion of the pellets, and the pellets can be inserted into the cladding tube. By passing through the guide tube immediately before, it can be inserted smoothly and reliably, and even if the pellet is caught and the insertion force of the pellet pushing tool increases sharply, the pellet is retained in the guide tube. In addition to being able to prevent scattering and disintegration, pellets can be pushed into the cladding tubes of many fuel rods at the same time, which is extremely efficient, and fully automatic operation in conjunction with the feeding of cladding tubes and pellets. It has an excellent effect that it is possible to save labor and improve reliability and safety.

In addition, since the overload prevention mechanism is equipped with an overload value adjustment mechanism that adjusts the magnitude of the overload that separates the pellet pusher, when inserting pellets into a long cladding tube, pellet insertion The load for pellet insertion will gradually increase as the number of pellets increases.Therefore, as the number of pellets inserted increases, the size of the overload at which the pellet pusher disengages is adjusted to an appropriate overload. By setting at any time, it is possible to achieve the smooth insertion of pellets and the prevention of pellet destruction and scattering due to overload at the same time.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention.
FIG. 1 is a perspective view showing the overall structure, FIG. 2 is a sectional view, and FIG.
FIG. 4 is a plan view, and FIG. 4 is an exploded perspective view of an overload prevention mechanism section. P ... Pellet, T ... Pellet tray, C ... Fuel rod cladding tube, 3 ... Pellet guide rod, 4 ... Pellet guide, 5 ... Pellet / rod guide, 6 ... Guide tube, 6a ... Slit, 10 ... Pellet pressing transfer mechanism,
10a …… Pellet pusher, 11 …… Overload prevention mechanism.

Claims (2)

(57) [Claims] 1. A pellet loading apparatus for inserting a plurality of pellets placed in a plurality of rows on a pellet tray into a plurality of coating tubes, respectively, wherein a plurality of pellets are provided at the tip of the pellet tray and guide the pellets. Pellet guide rods, a plurality of guide tubes provided on the tip end side of these pellet guide rods, having a slit in the longitudinal direction, and inserting and guiding the pellet row therein, the pellet guide rods, and the guide tubes. And a pellet guide provided between the guide tube for guiding the pellet into the guide tube, and linearly supporting the guide tube and the covering tube, and pellets for guiding the pellets in these guide tubes into the covering tube.・ The rod guide and pellets on the pellet tray are installed on each pellet row. A pellet pressing rod, a pellet guide, a guide tube, and a pellet / rod guide for pushing the pellet pressing transfer mechanism into the coating tube, and the pellet pressing transfer mechanism provided in the pellet pressing transfer mechanism. A pellet loading device, comprising: an overload preventing mechanism for separating an overloaded pellet pushing tool from the pellet pressing transfer mechanism when pushing out a pellet row. 2. The pellet according to claim 1, wherein the overload prevention mechanism is provided with an overload value adjusting mechanism for adjusting the magnitude of the overload for releasing the pellet pushing tool. Loading device.