JPH068903B2 - Fuel relay device in reactor vessel of liquid metal cooled fast breeder reactor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel relay device disposed in a reactor vessel of a liquid metal cooled fast breeder reactor, and more specifically, to a fuel transfer pot. The present invention relates to an improvement of a fuel relay device that conveys core components from the relay position inside the reactor vessel to the outside of the reactor vessel or from the outside of the reactor vessel to the relay position inside the reactor vessel.

<Prior Art> Conventionally, in a liquid metal-cooled fast breeder reactor, a fuel exchange mechanism and a fuel relay device have been used to take out spent fuel outside the reactor or load new fuel into the reactor. FIG. 4 shows a single-rotation plug, an off-set arm type fuel exchange mechanism 10 and a fuel relay device 20. The top opening of the reactor vessel 1 is eccentrically fitted to the fixed plug 2 and this fixed plug. The rotary plug 3 is shielded by the rotary plug 3 and the fuel exchange mechanism 10 is mounted on the rotary plug 3. An arm 11 and a gripper 12 are attached below the fuel exchange mechanism 10. On the other hand, the fuel relay device 20
Is an in-furnace chute 21 that penetrates through the fixed plug 2 and extends downward in the furnace vessel, a guide rail 22 provided along the inner surface of the in-furnace chute, and a link mechanism slidably attached to the guide rail. And a fuel transfer pot 24 engaged with the guide rail via 23. The link mechanism 23 is a hoisting mechanism 3 provided above the furnace vessel 1 by an index member (not shown) such as a wire, a chain or a metal tape.
0 can be used to move up and down in the furnace chute 21, and thus the fuel transfer pot 24 can also be moved up and down in the furnace chute 21 together with the link mechanism 23. Fifth
Figure A shows the fuel transfer pot 2 moving up and down in the internal chute 21.
4 shows that the fuel transfer pot 24 is housed in the in-reactor chute 21 having a C-shaped cross section by the action of the link mechanism 23 (a-a line in FIG. 4). However, as can be seen from FIGS. 4 and 5B, when the fuel transfer pot 24 descends and reaches below the in-core chute 21, the guide surface 25 (FIG. 4) at the lower end of the in-core chute and the link mechanism 23 act. The fuel transfer pot 24 moves from inside the in-reactor chute to the in-reactor fuel relay position 26 set near the outside of the chute (line bb in FIG. 4). In FIGS. 5A and 5B, reference numeral 22 denotes a guide rail arranged along the inner surface of the in-core chute 21, and reference numeral 4 denotes one core component contained in the fuel transfer pot 24.

Using the fuel exchange mechanism 10 and the fuel relay device 20 having such a configuration, the core components 4 including the fuel assembly (core fuel assembly, blanket fuel assembly, neutron shield, etc.) are taken out of the reactor. The procedure will be described with reference to FIGS. 4, 5A and 5B. First, the rotating plug 3
And the refueling mechanism 10 is rotated to move the gripper 12 to a desired position, and the desired core component 4 is pulled out. Next, the rotary plug 3 and the fuel exchange mechanism 10 are rotated again to move the gripper 12 to just above the in-reactor relay position 26, and then the gripper 12 is lowered to allow the fuel transfer pot 24 waiting at this position. The core component 4 is installed in. This core component 4 then rises in the in-core chute 21 together with the fuel transfer pot 24, and is taken out of the reactor via the chamber 31 and the out-of-reactor chute 32 above the reactor vessel 1. The procedure for loading the new core component 4 into the reactor may be performed in the reverse order of the above-mentioned taking-out procedure.

As can be seen from FIG. 4, the in-reactor chute 21 is bent outward in the radial direction of the reactor vessel at the upper part of the reactor. This is for the following reason. That is, a bearing stand 3a for rotating the rotary plug 3 with respect to the fixed plug 2 is provided between the two, and the chamber 31 is arranged so as not to interfere with the bearing stand 3a. It must be placed away from the center. On the other hand, the in-reactor chute 21 in the reactor vessel must be arranged as close to the center of the core as possible from the viewpoint of reducing the diameter of the reactor vessel. In order to satisfy both of these conditions, it is necessary for the in-reactor chute 21 to be bent outward in the radial direction of the reactor vessel on a vertical plane including the central axis of the reactor vessel in the upper part of the reactor.

Furthermore, the guide rail 2 allows the fuel transfer pot 24 to smoothly pass through the bent portion 21a of the in-core chute 21.
Although it depends on the action of the link mechanism 23 guided by 2, the bending portion 21 is required to smoothly operate the link mechanism 23.
When passing through a, the operating surface of the link mechanism 23 (the cross section of which is the fifth
(Represented by the chain line M in FIG. B) must coincide with the vertical plane containing the central axis of the reactor vessel.

<Problems to be Solved by the Invention> In the in-reactor fuel relay device 20 having the above-described configuration, the fuel transfer pot 2 at the in-reactor relay position 26 is provided.
As can be seen from the cross-sectional view of FIG. 6, the central axis of No. 4 and the central axis of the in-reactor chute 21 are the in-reactor chute central axis on the outer side and the fuel transfer pot central axis on the inner side along the radial direction of the reactor vessel. Are arranged so that

In such an arrangement, it is necessary to provide an in-reactor chute installation space on the outer side in the radial direction of the reactor vessel, and as a result, it is not preferable from the viewpoint of reducing the diameter of the reactor vessel 1. In other words, providing the space for installing the chute in the reactor outside in the radial direction of the reactor vessel is one of the constraint conditions for reducing the diameter and downsizing of the reactor vessel.

Therefore, the present invention has been made for the purpose of solving the above-mentioned problems and making the fuel relay device in the reactor vessel of the liquid metal cooling fast breeder reactor compact, thereby reducing the diameter of the reactor vessel. is there.

<Means for Solving Problems> In order to solve the conventional problems described above and achieve the object of the present invention, according to the present invention, an in-reactor chute extending below the inside of a cylindrical reactor vessel is provided. As it approaches the lower part of the chute, the guide rail provided along the inner surface of the chute is twisted. As a result, the center axis of the fuel transfer pot and the center axis of the chute at the fuel relay position in the reactor vessel were arranged along the radial direction of the reactor vessel in the past, whereas in the present invention, It will be arranged along a substantial circumferential direction.

In the present specification, the term "arranged substantially along the circumferential direction" means not only a state in which the elements are exactly arranged along the circumferential direction, but also a state of being deviated from the radial direction and approaching the circumferential direction. It also means that they are arranged.

<Operation> The fuel transfer pot engaged with the guide rail via the link mechanism moves up and down in the furnace chute by being guided by the guide rail. Therefore, when descending in the chute, the fuel transfer pot approaches the lower part. As the guide rail is twisted, the fuel transfer pot is also twisted around the pot center axis, and when the fuel relay position is reached, the center axis of the fuel transfer pot that has moved outside the chute and the center axis of the chute are It is arranged along a substantially circumferential direction.

Therefore, the diameter of the reactor vessel can be reduced as compared with the case where the central axis of the in-reactor chute and the central axis of the fuel transfer pot are arranged along the radial direction of the reactor vessel at the fuel relay position.

<Examples> The present invention will be further described below with reference to the examples shown in the drawings. FIG. 1 is a schematic diagram showing a fuel relay device in a reactor vessel of a liquid metal cooled fast breeder reactor.
The same members as those in the prior art shown in the figure are denoted by the same reference numerals as in FIG.

The in-reactor fuel relay device 40 of the present invention shown in FIG. 1 differs from the conventional device shown in FIG. 4 in that as the in-reactor chute 41 approaches its lower portion, a guide rail is provided along the inner surface of the chute. The point is to give 42 a twist. The number 42 in FIG. 1 shows a state in which two guide rails are overlapped in the vertical direction of the paper surface, but in 42a and 42b, the guide rails are twisted so that the guide rails that seem to overlap are in front. The state where one is seen on the side and the other on the back is shown.

At the in-reactor fuel relay position 46 in FIG. 1, the link mechanism 43 (FIG. 2C) is difficult to illustrate due to the positional relationship between the in-reactor chute 41 and the fuel transfer pot 44, and therefore the illustration thereof is omitted. However, the fuel transfer pot 44 is engaged with the guide rail 42 via the link mechanism 43 as in the conventional device shown in FIG.

2A, 2B and 2C are sectional views taken along the lines AA, BB and CC of FIG. 1, respectively, showing the in-reactor chute 41 and the fuel transfer pot due to the twisting of the guide rail 42. The change in the positional relationship with 44 is described. That is, at the position of line A-A in FIG. 1, the fuel transfer pot 44 is guided along the guide rail 42 while being housed in the in-core chute 41 (FIG. 2A). The positional relationship between 41 and the transfer pot 44 is exactly the same as that of the conventional FIG. 5A. Further, even when the fuel transfer pot 44 moves up and down the bent portion 41a of the in-core chute 41 above the position of the line AA in FIG. 1, as with the conventional FIG. In-furnace chute 41
Since the vertical plane including the center line of the link coincides, the link mechanism 43 can be operated smoothly. However, in the present invention, since the guide rail 42 is twisted as it approaches the lower portion of the in-core chute 41, the fuel transfer pot 44 is also twisted around its central axis at the position of the line BB in FIG. (Fig. 2B). In the state where the fuel transfer pot 44 is further lowered and finally moved to the fuel relay position 46 outside the in-core chute 41 by the action of the link mechanism 43, that is, in the position of the line C-C, the fuel transfer pot 4 is
4 is further twisted according to the twist of the guide rail 42 (FIG. 2C). FIG. 3 shows the in-reactor chute 4 at the in-reactor fuel relay position 46.
1 and the fuel transfer pot 44 are arranged in relation to the reactor vessel 1, which corresponds to FIG. 6 of the conventional apparatus. In the embodiment shown in FIG. 3, due to the twisting of the guide rail 42, the line connecting the central axis of the in-reactor chute 41 and the central axis of the fuel transfer pot 44 is θ≈70 ° from that in FIG. 6 in the radial direction of the reactor vessel. The position is deviated, and the arrangement position is closer to the circumferential direction of the reactor vessel 1. The twist angle θ is generally determined from the viewpoint that the distances from the outermost core components to the outer surface of the in-core chute 41 and the outer surface of the fuel transfer pot 44 at the in-core relay position are substantially the same. When the guide rail 42 is further twisted to bring the in-core chute 41 closer to the core constituent elements, the gripper 12 of the fuel exchange mechanism 10 approaches the in-core relay position 46 and the core constituent element 4 near the in-core chute. At this time, the arm 11 interferes with the in-furnace chute 41, which is not desirable.

When the present invention is applied to the fuel relay device in the reactor vessel of the liquid metal cooling fast breeder reactor of 1000 MWe class, the central axes of the internal chutes 21 and 41 and the center of the fuel transfer pots 24 and 44 at the internal fuel relay positions 26 and 46 The distance from the axis is generally
Since the diameter is about 300 mm, the diameter of the reactor vessel can be reduced by about 500 to 600 mm as compared with the conventional one shown in FIG.

Although the twist angle θ is set to about 70 ° in the above-mentioned embodiment, it can be appropriately selected in consideration of compatibility with the reactor structure.

Further, although the illustrated embodiment shows the fast breeder reactor provided with the single rotation plug, offset arm type fuel exchange mechanism 10, the fast breeder having the double rotation plug or triple rotation plug type fuel exchange mechanism. The present invention can also be applied to a furnace. In these cases, the fuel exchange mechanism does not necessarily need the offset arm, and may be a direct-acting type fuel exchange mechanism.

Further, in the illustrated embodiment, the fuel transfer pot 44
Although it is structured to be sandwiched between two guide rails 42a and 42b from both sides, a monorail type in which only one guide rail is arranged may be used. The cross-sectional shape of the out-of-furnace chute 41 is not limited to the C-shaped substantially cylindrical shape, and may be any cross-sectional shape as long as it has a function of reinforcing the guide rail in terms of strength.

<Effects of the Invention> As can be seen from the above description, according to the present invention, the guide rail provided along the inner surface of the inner chute extending below the inside of the reactor vessel of the liquid cooling fast breeder reactor is twisted. With a simple structure, the center axis of the in-reactor chute and the center axis of the fuel transfer pot at the fuel relay position in the reactor vessel are arranged along the substantial circumferential direction of the reactor vessel. The diameter of the reactor vessel can be reduced as compared with the case where they are arranged along the radial direction, and therefore the construction cost can be reduced.

It should be noted that the above description is directed to an example in which the present invention is applied in order to reduce the diameter of the reactor vessel by compacting the fuel relay device arranged in the reactor vessel. When applied to the fuel relay device in the outer fuel storage tank, the diameter of the outer-reactor fuel storage tank can be similarly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing an embodiment of an in-reactor fuel relay device of the present invention, and FIGS. 2A, 2B and 2C are A of FIG.
-A sectional enlarged view taken along the lines A, BB and CC, FIG. 3 is an enlarged sectional view taken along the line III-III in FIG. 1, and FIG. 4 is an example of a conventional in-reactor fuel relay device. 5A and 5B are enlarged sectional views taken along line aa and bb of FIG. 4, and FIG. 6 is an enlarged sectional view taken along line IV-IV of FIG. is there. DESCRIPTION OF SYMBOLS 1 ... Reactor vessel, 4 ... Core component, 10 ... Fuel exchange mechanism, 40 ... Fuel relay device, 41 ... In-reactor chute, 42,
42a, 42b ... Guide rail, 43 ... Link mechanism, 44 ... Fuel transfer pot, 46 ... In-reactor fuel relay position.

Claims (1)

[Claims] 1. A link mechanism provided with a guide rail along the inner surface of an in-reactor chute extending inward from the outside of a cylindrical reactor vessel of a liquid metal cooled fast breeder reactor and slidably attached to the guide rail. A fuel transfer pot engaged with the guide rail via the
A fuel relay that enables the fuel transfer pot to be moved from the chute to the relay position or from the relay position into the chute by the link mechanism at a fuel relay position in the reactor vessel provided under the chute and near the outside of the chute. In the apparatus, as the in-reactor chute extending downward inside the reactor vessel approaches the lower part thereof, the guide rail provided along the inner surface of the chute is twisted, thereby centering the fuel transfer pot at the relay position. A fuel relay device in a reactor vessel of a liquid metal fast breeder reactor, wherein a shaft and a central axis of the chute are arranged along a substantially circumferential direction of the reactor vessel.