JPS5928398Y2 - Liner for transporting fuel assemblies - Google Patents

Description

[Detailed description of the invention] The present invention is a liner for transporting fuel assemblies, in particular, when moving or transporting fuel assemblies, it prevents vibrations of the fuel rods and support grids as well as movements that affect each other, and This relates to liners for maintaining the mechanical integrity of fuel assemblies.

A fuel assembly, which is an assembly of fuel rods for a nuclear reactor, cannot be expected to react uniformly unless the dimensions of the fuel rod itself and the mutual spacing between each fuel rod are precisely maintained. Vibration and movement of the fuel rods must be avoided as they cause deformation of the fuel rods.

Therefore, much consideration has been given to the transportation of fuel assemblies.

However, when the fuel assembly is moved or transported, the various elements constituting the fuel assembly, such as fuel rods and support grids, often generate vibrations.

In this case, since the fuel rods are supported by the support grid, if the vibrations are large, there is a possibility of damaging not only the fuel rods but also the springs of the support grid through the vibrations.

Conventionally, in order to prevent fluctuations during transportation of the assembled fuel rods as described above, a filler such as an insertion plate having a recess corresponding to the outer periphery of the fuel rods is individually inserted at each fuel element interval. However, since the fuel element is inserted at every interval, the total loading amount increases, which causes management problems such as missing fuel, and since it is a single item, there are variations in manufacturing accuracy, which reduces the seismic protection effect. There are also problems such as variations in the structure, weak overall shooting strength against the aggregate because it is not an integral structure, and the lack of a function to protect the support grid for the same reason as above). I am not even a distant relative.

In addition, a liner inserted into the fuel element gap has been proposed in which the element gap is filled by overlapping thin plate liners, but this also increases the amount of thin plate liners loaded and leaves management problems. However, due to variations in manufacturing accuracy and lack of firing strength against the fuel assembly, the protective function of the fuel assembly is not fully fulfilled.

Furthermore, when transporting fuel assemblies, a transport container is usually used, or the structure of this transport container is designed to fix the assembly support grid, but this fixation actually deforms it into a support grid. This leaves problems in the ability to protect the support grid.

´ ゛：The present invention addresses the above-mentioned current situation, solves various problems of existing transport liners, and ensures thorough protection of support grids as well as vibration prevention during transport of fuel assemblies. In this method, a liner consisting of a member of both the first liner and the second liner having a vibration prevention function is disposed on the outermost fuel element of the fuel assembly near the support grid. Integral bonding of the liner parts prevents movement of the fuel rods and support grid parts and movements that affect each other, maintaining the integrity of the fuel assembly during transportation and increasing the strength of the support grid parts. The purpose is to provide a reinforcing effect.

That is, the present invention includes a first liner member that surrounds the outermost fuel rod of a fuel assembly and is provided with a spacing piece for insertion into the fuel gap, and a first liner member that is provided with a spacing piece for inserting into the fuel gap, and a fuel liner that is perpendicular to the spacing piece of the liner member. The invention features a liner member configuration comprising a second liner member interconnected throughout the array of rods.

Hereinafter, the present invention will be explained in more detail with reference to the figures.

1 and 2, A and C respectively illustrate a first liner member and a second liner member that constitute the liner of the present invention, and the first liner member A is the As shown in Fig. 1, a flat surface is made up of a substrate 1 having a length corresponding to the length of one side of a fuel assembly made of thin plate material, and a gap piece 2 extending forward from the substrate 1 to be inserted into a fuel element gap. The second liner member B is composed of a thin rectangular thin plate base 5 as shown in FIG.

Each spacing piece 2 extending forward from the base plate 1 of the first liner member A is tapered at its distal end to facilitate insertion into the fuel element gap, and at the midpoint of its length, the spacer piece 2 extends forward from the base plate 1. A recessed portion 3 for fitting and coupling the second liner member B is formed on a parallel line.

Each spacing piece 2 forms a space between the adjacent spacing pieces that accommodates the fuel element from the outermost circumference of the fuel assembly or up to the next second circumference, and holds it securely by elastic force or the like. The width of the four-part space formed by the adjacent spacing pieces may be approximately equal to the diameter of the fuel rod, and the forward extension length may be sufficient to support the outermost and second round fuel elements of the fuel assembly. A length, for example, about 1.5 times or more than the fuel rod diameter, preferably 1.5 to 3 times, is necessary and sufficient.

Further, since the inner part of the recessed space supports the fuel rod along its outer periphery, it is preferable that the inner part has the same curvature as the outer peripheral surface of the fuel rod.

Incidentally, reference numeral 4 denotes notches into which the ends of the second liner member B, which are provided near both ends of the substrate 1, are fitted and supported at a part of the corner.

On the other hand, the second liner member B shown in FIG. It has an elongated rectangular shape with the sides as long, and the upper and lower edges are tapered to easily accommodate the recessed part 3, and the second liner member B is placed near both ends of the fuel assembly. Notches 6 are formed at some of the corners so that they interlock when perpendicular to each other.

The first and second liner members are preferably made of a material that does not contain chlorine, fluorine, or boron, such as polyethylene, polystyrene, or nylon, or made of stainless steel, zirconium alloy, Made of metal such as copper alloy.

FIGS. 3 and 4 show a state in which the first liner member A and the second liner member B as described above are combined and installed around the fuel assembly.

That is, the transportation liner of the present invention is constructed by combining the two liner members A and B.

As can be seen from the figure, the first liner member A is arranged around the outer periphery of the fuel assembly, and four pieces are used to form a quadrangular shape in the figure, and are arranged at the outer periphery of the fuel assembly. The spacing pieces 2 are inserted into the gaps between the fuel elements 7 so as to protect the outer circumference and the second circumference of the fuel elements.

In general, it has been experimentally confirmed that when a lateral load is applied to the fuel assembly support grid, the effect is absorbed only by the outermost layer of the fuel rods.

Therefore, assuming loads that may occur during transportation, it is necessary and sufficient to protect the outermost and second round fuel elements as described above.

Then, the second liner member B passes through the recessed portions 3 provided in the spacer piece 2 on the inner circumferential side of the first liner member A disposed as described above, and the second liner member B is inserted at the four corners thereof as shown in FIG. As shown in FIG. 1, they are assembled into a lattice-like structure using notches, and their tips are fitted and supported in the notches 4 of the first liner member A, so that they are connected to the first liner member A as an integral structure. .

Incidentally, at this time, if necessary, the joint portions of both liner members may be temporarily fixed.

Thus, localized fuel element motion is absorbed by the liner and the load is distributed.

In addition, it is noteworthy that the position of the fuel element can be fixed by assembling both liner parts A and B in one piece, and this allows the liner of the present invention to be installed near the support grid. It is possible to prevent a large load from being applied to the grid, the spring portion, and the contact portion with the fuel element, and protect the support grid.

In addition, in the illustrated example, the spacer pieces 2 located perpendicularly at the four corners are formed to be slightly shorter than the spacer pieces 2 at the middle part so that they do not get in the way of each other, but this is not necessarily required. Instead, the length of the intermediate spacer piece may be formed to match the length of the short end spacer piece.

Liners that are assembled in one piece as described above are usually
Upper or lower part or upper and lower parts of the support grid of the fuel assembly 1
Load at a position within 5Qmm, preferably about 50mm.

FIG. 5 shows an example adapted to a PRW type fuel assembly.

Although not shown, the nuclear fuel rods 7 and control rod guide tubes 9 pass through the lattices of a support lattice 8 arranged at appropriate intervals in the longitudinal direction, and are supported by springs to form the upper and lower nozzles 1.
1 are held from above and below to constitute a fuel assembly, and in the vicinity of each support grid 8, seven liners L□ to L7 are loaded in the figure according to the number of support grids.

Generally, like PRW type fuel assemblies, other BWR type, A
For those designed with a larger number of fuel elements and longer spacing between support grids than the TR type, it is very important to prevent vibrations during transportation, and the use of the liner of the present invention is effective.

When loading liners, it is effective to place the liners at equal intervals as much as possible or with emphasis on positions where deformation is particularly likely to occur, taking into consideration pressure equalization in the longitudinal direction of the fuel rods.

Furthermore, it is advantageous in terms of liner manufacturing efficiency to keep the height and thickness of the liner loaded in the fuel assembly, the length of the spacer pieces, etc. as constant as possible.

However, it is natural to create a plurality of types in advance and apply them to each type of fuel assembly.

When loading the liner of the present invention as described above, first insert the spacing piece of the first liner member A into the gap between the fuel elements, hold it by elastic force as appropriate, and then insert the second liner member B. Alternatively, the second liner member B may be inserted into the fuel element gap in advance, and then the second liner member A may be installed and coupled with the second liner member B.

As explained above, the present invention is constructed by integrally joining both the first and second liner members, so it is easy to attach and remove from the fuel assembly, and is far more convenient than conventional liners. Since only a small number are required, precision in machining and inspection can be achieved, and since the number is small and one side is large in shape, there is no risk of contamination in the fuel.
It is also extremely easy to manage fuel assemblies.

In addition, by assembling both as an integral structure, local movement of the fuel element is absorbed by the liner, the load is dispersed, and the position of the fuel element is also fixed, preventing large loads from being applied to the support grid and protecting the support grid. It also has the function of

[Brief explanation of the drawing]

Fig. 1 shows the first liner part constituting the present invention, and Fig. 2 shows the second liner part constituting the present invention, in which A is a front view, the mouth is a side view, and C is a plane. It is a diagram. Figures 3 and 4 are views showing an example of the liner of the present invention. Figure 3 is an assembled plan view, Figure 4 is an enlarged view of the main parts, and Figure 5 shows how the liner of the present invention is installed in a fuel assembly. FIG. A...First liner part, B...Second liner part, L...Liner, 1...
...First liner substrate, 2... Spacer piece, 3
. . . Concave cutout, 5 . . . Second liner base, 6 . . . Notch, 8 .

Claims (1)

[Scope of utility model registration request] 1. During transportation, it is installed near the support grid of the nuclear fuel assembly,
A transport liner for protecting nuclear fuel assemblies, the liner comprising a base plate and a number of spacing pieces extending from the base plate in a comb-like shape and inserted into gaps between fuel elements of the fuel assembly. a first liner member that is fitted into a recess provided in the spacer piece perpendicular to the extending direction of the spacer piece of the second liner member and coupled to the first liner member; The recessed space formed by the adjacent spacing pieces of the first liner member has an inner deep portion formed with a curvature corresponding to the outer circumferential curved surface of the fuel rod, and The recessed space has a width sufficient to hold the fuel rods, and a length extending into the fuel element gap is at least sufficient to hold the two fuel rods with the spacing pieces that sandwich the fuel rods when the spacing pieces are inserted into the fuel element gaps. 1. A liner for transporting fuel assemblies, characterized in that the second liner member is interconnected parallel to the substrate between the plurality of fuel rods accommodated in the recessed space. 2. The insertion side tip of the spacer piece of the first liner member is formed in a tapered shape, and the upper and lower surfaces of the second liner member are formed in a tapered shape as described in claim 1 of the utility model registration claim. Liner for transporting fuel assemblies. 3.Registration of a utility model in which the second liner member has a notch that supports another second liner member that is attached to each other in a direction orthogonal to each other at a part of the corner of the fuel assembly close to both ends. A liner for transporting fuel assemblies according to claim 1 or 2. 4. The first and second liner members contain chlorine, fluorine,
The liner for transporting fuel assemblies according to claim 1, 2, or 3, which is made of an organic material that does not contain boron as a component. 5. The first and second liner members are polyethylene. The liner for transporting fuel assemblies according to claim 4, which is made of a material selected from polystyrene or nylon. 6. The fuel assembly according to claim 1, 2, or 3, in which the first and second liner members are made of a material selected from stainless steel, zirconium alloy, or copper alloy. Liner for body transportation.