JPS60107597A - Fuel exchanger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a refueling device for a fast breeder reactor.

[Technical background of the invention]

FIG. 1 shows a schematic configuration of a fast breeder reactor. Inside a reactor vessel 1, a reactor core consisting of a large number of fuel assemblies 2, . . . is constructed on a core support mechanism 3. Further, liquid sodium 4 is contained within the reactor vessel 1 as a coolant.

The upper opening of the reactor vessel 1 is closed by a shielding flag 5. The shielding plug 5 includes a fixed flag 6 having a circular hole 6a at an eccentric position and fixed to the reactor vessel 1, and a rotary plug 7 rotatably attached to the circular hole 6a.

A core upper mechanism 9 that holds a control rod drive mechanism 8 and an oval flag 1o are both attached to the rotary plug 7 at eccentric positions, and a fuel exchange device 11 is attached to the oval plug 10.
is the installation.

During operation, the upper core mechanism 9 is connected to the reactor vessel 1.
, that is, at the center of the fixed plug 6.

A coolant inflow pipe 12 and a coolant outflow pipe 13 are arranged outside the reactor vessel. and coolant inlet pipe 12
One end passes through the lower part of the peripheral wall of the reactor vessel 1 and is introduced below the core support mechanism 3, and one end of the coolant outflow pipe 13 is connected to the peripheral wall of the reactor vessel 1 and is introduced above the core support mechanism 3. Furthermore, a guard vessel 14 is provided outside the reactor vessel 1 to protect it, and this guard vessel 14 has a guard vessel 14 that protects the coolant inflow pipe 12 and the coolant outflow pipe 13, respectively. , J e are provided.

Figure 3 shows the fuel exchange device 1, and 17 in the figure.
is a rotating housing that also has a mechanism for rotating in any direction and mechanically holding down the fuel assemblies 2 around the fuel assembly 2 to be replaced. An elevating housing 18 is inserted into the rotating housing 17 so as to be vertically movable.

The elevating housing 18 has a cylindrical shape, and a pantograph arm 19 made of a link mechanism is attached to the lower part of the elevating housing 18. A gripper mechanism 20 for gripping and IIGLing the fuel assembly 2 loaded in the core is attached to the tip of the Nonontagraph farm 19, and a gripper mechanism 20 for opening and closing the pantograph arm 19 is attached to the upper part of the elevating housing 17. There is a driver mlJ section 21 which houses various driving and sensing mechanisms such as opening/closing the mechanism 20 and sensing the fuel position, and the driving section 21 is covered by a casing 22 which also serves as a cask.

A wire rope winding drum-type winding device 23 is provided on the upper part of the casing 22, and this winding device 23
The drive section 21 is lowered with a wire rope via a load cell.

The rotating housing 17 is inserted through a guide sleeve 25 installed in a through hole 24 provided in the rotating Siragua, and is rotatably supported via a bearing 26 .

Further, on the rotating plug z, the rotating housing 17
A drive part support body 29 to which a swing drive mechanism 27 for swinging and a hold-down drive mechanism 28 for lifting and lowering are attached.
is installed.

A door valve 30 for sealing and shielding during operation of the nuclear reactor is provided at the upper part of the drive part support 29, and this door valve 30 is connected to a door valve 3 provided at the lower part of the casing 22.

A connecting member 32a is provided on the side of the pivot housing 17.
, 32b, a gripper guide tube 33 is attached vertically.

This gripper guide 133 is used for pulling out the fuel assembly 2,
It guides the gripper mechanism 20 during insertion and rotation, and its inner diameter is larger than the outer diameter of the gripper mechanism 20, and in order to absorb misalignment between the gripper mechanism 20 and the fuel assembly 2, it becomes larger toward the bottom. It is said to be the diameter.

Therefore, when exchanging fuel, the door valve 30 on the rotary plug 7 and the door valve 3 on the casing 22 side are connected, and after replacing the inside of the casing 22 with argon gas, the elevating housing 18 is lowered into the reactor vessel 1. The pantograph arm 19 is opened and the gripper mechanism 20 is introduced into the guide tube 33 of the gripper mechanism 9. Next, the rotating plug 7 and the rotating housing 17
is rotated, and the gripper guide tube 33 is positioned above a predetermined fuel assembly 2 by the combination of the rotation angles of both. Then, the gripper mechanism 20 is lowered to grasp the fuel assembly 2,
This is pulled up into the gripper guide tube 33 and transferred to a predetermined position. Furthermore, the fuel assembly 2 is inserted in the same manner, and the fuel exchange operation is completed.

Note that the pulling out and insertion of the fuel assembly 2 is performed using the hoisting device 2.
3.

After the fuel is replaced, the pantograph arm 19 is folded, the gripper mechanism 20 is pulled up together with the lifting housing 18 into the casing 22, the door valves 30 and 31 are closed and disconnected, and the gripper mechanism 20 is inspected.

[Problems with background technology]

In the conventional fuel exchange device, when the fuel assembly is gripped by the gripper mechanism 20 and inserted into the reactor core, if the fuel assembly is curved, the fuel assembly 2a is guided by the gripper guide tube 33 and lowered. However, since the inner diameter of the gripper guide tube 33 increases downwardly, the lower end of the curved fuel assembly 2a comes into contact with the top end of the surrounding fuel assembly 2b, as shown in FIG. There was a risk that the insertion of the child's body would become adulterous.

Therefore, in order to avoid such a situation, as shown in FIG. 5 and FIG. The free end of each leaf spring 34 extends downward and is inclined in the direction of approaching the gripper guide tube 33, and the fuel assembly 2a is curved as shown by the imaginary line in FIG. However, the position of the lower end is corrected on the axis of the gripper guide tube 33 by the plurality of leaf springs 34 as shown by the solid line, and the position of the lower end is corrected on the axis of the gripper guide tube 33 as shown in FIG. can be inserted into.

However, since the plate springs 34 are fixed inside the gripper guide tube 33, the reactor vessel 1 must be taken out to the outside together with the rotating housing 17 and the chrysoscopic guide tube 33. However, maintenance and inspection are difficult, and a high level of quality is required to maintain soundness over a long period of time.

[Purpose of the invention]

The present invention was made based on these circumstances, and
The purpose of this is to equip the inside of the gripper guide tube introduced into the reactor vessel with multiple leaf springs, so that even if the fuel assembly is curved, its lower end position can be regulated on the axis of the gripper guide tube. A fuel exchange device that can be inserted into the reactor core without coming into contact with surrounding fuel assemblies, and that can easily take out the machine springs outside the reactor vessel, thereby alleviating demands for high quality. Our goal is to provide the following.

[Summary of the invention]

In order to achieve the above object, the fuel exchange device of the present invention has a gripper guide tube introduced into the reactor vessel with its axis oriented vertically, and a gripper guide tube that can be engaged with and detached from the handling head of the fuel assembly. A gripper structure that is housed in a guide tube so that it can be raised and lowered and can be taken out of the reactor vessel, and a plurality of plates that extend their free ends downward and are inclined in a direction that brings their target ends closer to the axis of the gripper guide tube. 10 springs are arranged at equal intervals in the circumferential direction and are housed in the gripper guide tube so as to be able to rise and fall freely.
A centering mechanism is provided that protrudes within the gripper guide tube to restrict the lower movement of the centering mechanism. A locking mechanism that locks the centering mechanism at a regulated position by a stopper part, is suspended by the gripper mechanism, and is taken out of the reactor vessel together with the centering mechanism. be done.

Therefore, the centering mechanism allows the lower end of the fuel assembly to be positioned on the axis of the gripper guide tube, thereby reliably preventing the lower end of the fuel assembly from coming into contact with the top end of the circumferentially recessed fuel assembly during insertion.

Further, the centering mechanism and the locking mechanism can be suspended from the gripper mechanism and taken out of the reactor vessel, and maintenance and inspection can be easily performed outside the reactor vessel.

At this time, the leaf springs for position regulation can be easily taken out of the reactor vessel together with the gripper mechanism as part of the centering mechanism, making maintenance and inspection easier, so the requirements for high quality are relaxed. That will happen.

[Embodiments of the invention]

Examples of the present invention will be shown below.

First, FIGS. 9(a) and 9(b) show a first embodiment. The figure (,) shows the relationship between a part of the fuel exchange device, that is, the gripper guide tube 35, and the centering mechanism 36 and the locking mechanism 37 housed therein. It shows the relationship between the stop mechanism 37 and the gripper mechanism 38.

An annular stopper portion 39 is protruded from a lower position on the inner peripheral surface of the gripper guide tube 35, and an annular locking recess 4θ is formed in the inner peripheral surface of the stopper portion 39.

Further, the centering mechanism 36 is formed by attaching one end of each of a plurality of leaf springs 42 to the lower part of a stepped cylindrical body 41 whose upper half has a large diameter. The stepped portion 43 is brought into contact with the stone 9 portion 39 from above. A flange portion 44 is provided on the inner periphery of the upper end of the stepped cylindrical body 41.
A plurality of circular holes 45, for example four, are provided in the peripheral wall of the small diameter portion at equal intervals in the circumferential direction. Further, each of the leaf springs 42 has a free end extending downward and is inclined in a direction in which the free end approaches the axis of the gripper guide tube 35.

The locking mechanism 37 has a stepped cylindrical shape with an upper half having a larger diameter, and has a seven-rung portion 46 on the inner periphery of the upper end, and the upper half has a larger diameter than the stepped part of the centering mechanism 36. It is fitted into the upper semi-large diameter portion of the cylindrical body 41 and can be moved up and down a certain amount with respect to the centering mechanism. The lower radius portion of the locking mechanism 37 is fitted into the lower semi-small diameter portion of the stepped cylindrical body 41, and has a small diameter centering mechanism release portion 47 at the lower end of its outer periphery.

A hard sphere 48 is accommodated in the circular hole 45 of the centering mechanism 36 . The locking mechanism 37 is shown in FIG.
), the hard sphere 48 is pushed outward by the outer circumferential surface of the locking mechanism 37 to be recessed into the locking recess 40. Therefore, in this state, the centering mechanism 36 is locked at a fixed position within the guide tube 35. On the other hand, when the locking mechanism 37 is in the raised position as shown in FIG. 9(b), the centering mechanism release portion 47
faces the hard sphere 48. Therefore, the hard sphere 48 can escape from the locking recess 40, and the centering mechanism 36
is released from the locking position of the gripper guide tube 35, and the upward movement becomes possible.

The gripper mechanism 38 is conventional, consisting of a gripper rod 49 and a plurality of latch claws 50 that can protrude outward from the lower outer periphery of the gripper rod 49. When gripping the fuel assembly 2, At the upper end of the fuel assembly 2...
After inserting the lower end of the grit mother rod 49 into the drying head, the latch pawl 50 is projected outward and engaged with the drying head.

Therefore, the gripper mechanism 38 can be engaged with and disengaged from the locking mechanism 37 in the same manner as the fuel assembly 2 is engaged with and disengaged from the handling head. That is, when the gripper rod 49 is positioned within the locking mechanism 37 at the lower end of the grit or rod 49 and the latch claw 50 is projected outward and the gripper rod 49 is raised, the latch claw 50 is caught on the flange portion 46 and locked. The mechanism 37 can be pulled up. In addition, the latch claw 50
By placing the gripper rod 49 within the gripper rod 49, the locking mechanism 37 can be released.

Note that the parts not shown in FIGS. 9(a) and 9(b) are the same as the configuration shown in FIG. 3, and therefore their description will be omitted.

When taking out the fuel assembly 2 from the core with the fuel exchange device configured as described above, the gripper guide pipe 35 is positioned above a predetermined fuel assembly 2 and the gripper rod 49 is lowered. The grits or rod 49 descends while pushing the plurality of leaf springs 42 outward. Then, connect the lower end of the gripper rod 49 to the fuel assembly 2.
When the gripper rod 49 is raised after being inserted into the handling head of the fuel assembly 2 and the latch pawl 50 is projected, the fuel assembly 2 is pulled up into the Glitz R guide tube 35 while the outer periphery is in sliding contact with the leaf spring 42.

Furthermore, when inserting a new fuel assembly 2 into a predetermined position in the reactor core, even if the fuel assembly 2 is curved, the lower end position of the fuel assembly 2 is fixed to the gripper guide by a plurality of plate blades 42. Since it is regulated on the axis of the tube 35, it does not come into contact with the top end of the surrounding fuel assembly.
Can be inserted smoothly.

Furthermore, when the grip/IP mechanism 38 is taken out of the furnace after completing the fuel exchange work, the gripper rod 4 is
By positioning the lower end of 9 within the locking mechanism 37 and protruding the latch claw 50 and raising the gripper rod 49, the locking mechanism 37 is pulled up and the centering mechanism 36 is moved to the locking position of the gripper guide tube 35. When the gripper rod 49 is further raised, the locking mechanism 37
and the centering mechanism 36 are lifted together, and the gripper mechanism 3
8 can be taken out of the furnace.

Therefore, since maintenance and inspection of the centering mechanism 36 and the locking mechanism 37 can be easily performed outside the furnace, the leaf spring 4
There is no need to require a high level of quality that can maintain soundness for a long period of time for second-class quality as well.

Next, FIGS. 10(a) and 10(b) show a second embodiment, in which the inner peripheral surface of the gripper guide tube 35 has a locking recess 40 similar to the first embodiment, and a locking recess 40 below this. Annular strami 4 and 5 are separately protruded at the positions.

Further, in the figure, reference numeral 52 denotes a centering mechanism, which has a configuration in which one end of each of a plurality of plate springs 42 is attached to the lower part of the inner periphery of a cylindrical body 54 having a flange portion 53 on the inner periphery of the upper end. As in the first embodiment, these leaf springs 42 extend their free ends downward and are tilted in the direction of bringing the free ends closer to the axis of the gripper guide tube 35. Further, the centering mechanism 5 is brought into contact with the stopper portion 51 from above on the outer periphery of the cylindrical body 54.
A stepped portion 55 is formed to restrict the descending movement of 2.

Further, a plurality of, for example, four, elastic pieces 56 are attached to the outer periphery of the cylindrical body 54 of the centering mechanism 52 as a locking mechanism (however, only one elastic piece is shown in the figure). Each elastic piece 56 has a lower end attached to the outer periphery of the cylindrical body 54 and has a locking convex portion 57 on the outer surface of the upper end. And Figure 10 (
As shown in a), with the stepped portion 55 in contact with the stopper portion 51 from above and the downward movement of the centering mechanism 52 being restricted, the locking convex portion 57 is recessed into the locking recess 40, and the centering It is configured to lock the ejecting mechanism 52 in a fixed position.

Further, an opening 58 is provided in the peripheral wall of the cylindrical body 54 to allow each elastic piece 56 to deflect inward.

The grit 9 mechanism 38 is similar to the first embodiment, i.e. conventional, and by introducing the lower end of the gripper rod 49 into the centering mechanism 52 and causing the latch pawl 50 to protrude outward and rise. As shown in FIG. 10(b), the latch claw 50 is hooked on the flange portion 53, and the centering mechanism 52 can be lifted up. At this time, the elastic piece 56 bends inward, causing the locking convex portion 57 to escape from the locking recess 40, allowing the centering mechanism 52 to rise.

It should be noted that the parts not shown in FIGS. 10(a) and 10(b) are the same as the configuration in FIG. 3, and therefore the description thereof will be omitted.

Even with the above configuration, the fuel assembly 2 lifted by the Grits 9 mechanism 38 has its lower end fixed to a plurality of leaf springs 4.
2 on the axis of the Glitz Q guide tube 35, even a curved fuel assembly can be inserted smoothly without coming into contact with surrounding fuel assemblies.

In addition, the gripper mechanism 38 operates the centering mechanism 52 and the elastic piece 5.
6 can be lifted up and taken out of the reactor vessel, and maintenance and inspection thereof can be easily performed, so that the requirements for high quality of the leaf spring 42 and the like can be relaxed.

〔Effect of the invention〕

As detailed above, according to the present invention, insertion of a curved fuel assembly can be smoothly performed by regulating the lower end position with a plurality of leaf springs, and moreover, the leaf springs can be inserted into the centering mechanism. It can be taken out of the reactor vessel as a part, and the requirements for high quality of leaf springs etc. can be relaxed.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view showing the schematic configuration of a tank-type fast breeder reactor, Figure 2 is a plan view of the same, Figure 3 is a vertical cross-sectional view of a conventional fuel exchange device, and Figure 4 is a problem with the conventional device. FIG. 9 is a schematic cross-sectional view for explaining the fuel exchange operation according to the prior art; FIG. 9 (a) + (b)
10(a) and 10(b) are longitudinal sectional views of the lower portion of the gripper guide tube showing the second embodiment of the present invention. 1...Reactor vessel, 2, 2a, 2b...Fuel assembly, 35...Gurirami 4 guide '11, s6. s2...
- Centering mechanism, 37... Locking mechanism, 38 thread gripper mechanism, 39.57... Strami R section, 40... Locking recess, 41... Stepped cylindrical body, 42... Plate plate Hey, 44...
- Circular hole, 48... Hard sphere, 56... Elastic piece (locking mechanism), 57... Locking convex portion. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 1 Figure 5 Figure 6 Figure 4 Figure 9M (a) Mumu Figure 10 (a)

Claims (1)

[Scope of Claims] (1) Inside the gripper guide tube introduced into the reactor vessel with its axis facing vertically, the fuel assembly can be accommodated in the gripper guide tube in a manner that is detachable from the handling head and can be raised and lowered within the gripper guide tube. A gripper mechanism that can be pulled out of the reactor vessel, and a plurality of leaf springs whose free ends extend downward and are inclined toward the axis of the guide tube, which are arranged at equal intervals in the circumferential direction. a centering mechanism for regulating the position of the lower end of the fuel assembly, which is housed in the gripper guide tube such that it can be raised and lowered and is suspended in the gripper guide tube by the gripper mechanism, on the axis of the gripper guide tube by the plurality of leaf springs; And the straight horn J? which is provided protrudingly within the guide tube of the Grilami 4 and restricts the downward movement of the centering mechanism. and a locking mechanism that locks the centering mechanism in a regulated position by the stock t4 and is suspended from the gripper mechanism and taken out of the reactor vessel together with the centering mechanism. fuel exchange equipment. (2) The centering mechanism holds a hard sphere, and the locking mechanism has a cylindrical shape that is engaged with the centering mechanism so that it can be raised and lowered by a certain amount, and in the lowered position, a part of the hard sphere is held. The hard sphere is inserted into a locking recess formed on the inner peripheral surface of the gripper guide tube to lock the centering mechanism at a certain position within the gripper guide tube, and is pulled up by the gripper mechanism to cause the hard sphere to escape from the locking recess. A fuel exchange device according to claim (1), characterized in that: ! 31. The fuel exchange device according to claim (2), wherein the hard sphere is accommodated and held in a circular hole provided in the peripheral wall of the cylindrical body of the centering mechanism. (4) The locking mechanism comprises an elastic piece having one end attached to the centering mechanism and a free end elastically recessed into a locking recess formed on the inner peripheral surface of the guide tube. The fuel exchange device according to scope (1).