JPH0361899A - Transporting method for nuclear fuel assembly - Google Patents

Abstract

PURPOSE:To restrict and support nuclear fuel rods and to shorten a working time by providing a transport liner wherein liquid having cooling and solidifying characteristics is sealed in an inner space. CONSTITUTION:When a nuclear fuel assembly is transported to a destination, at first a liner is kept in a normal temperature state. Sealed liquid is made to keep a liquid state. The liner wherein the sealed liquid is in the liquid state is inserted between the fuel rods of the nuclear fuel assembly. Since a liner main body 10 has flexibility in the normal temperature state, the liquid sealed in a space 12 in the liner main body 10 is moved in the space 12 extending in the insertion direction. The outer shape of the liner main body 10 becomes smaller than the size between the fuel rods of the nuclear fuel assembly. Thus the liner main body 10 is inserted between the fuel rods without excessive force. At this time, the insertion and the removal of the transporting liner between the fuel rods can be performed readily, and other devices are not required for the insertion and the removal. Therefore, the working time is shortened.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a nuclear fuel assembly that suppresses vibrations of nuclear fuel rods of the nuclear fuel assembly when the nuclear fuel assembly is transported to a destination. (Prior art) As shown in FIG. 4, a nuclear fuel assembly generally includes a plurality of fuel rods in a fuel channel 1 whose upper and lower ends are supported by an upper tie plate 2 and a lower tie plate 3, respectively. It is formed by arranging and mounting the fuel rods 4 and water rods 5, and by arranging a plurality of spacers 6 in the axial direction of the fuel rods 4, the lateral vibration of the fuel rods 4 is restrained and a coolant flow path is secured. I try to do that.

On the other hand, when transporting nuclear fuel assemblies to their destinations, a liner is placed between the fuel rods to prevent the spacers and fuel rods from sliding due to the vibrations generated during transport and to prevent contact friction scratches from forming on the fuel rods. is installed, and the fuel rods are fixedly placed.

As shown in FIG. 5, the liner is made of polyethylene resin and has ribs 8, 8, . . . on both sides of the flat main body 7.
The ribs 8 on the negative side are not located on the same plane as the ribs 8 on the other side, but are arranged alternately. Further, the insertion width of the liner, that is, the distance between the tip surface of the rib on the negative side and the tip surface of the rib on the other side, is set to a value approximately 1 mm larger than the dimension between the attached fuel rods 4.4.

When transporting nuclear fuel assemblies to their destination using liners of the above type, it is necessary to securely fix the fuel rods.
The ribs must be inserted between the fuel rods to maintain a compressed state, which increases friction between the liner and the fuel rods, making it difficult to insert and remove the liner, resulting in poor workability.

Therefore, a liner for transporting nuclear fuel assemblies is formed into a sealed container shape using an airtight and flexible material, and after being inserted between fuel rods, fluid is sealed in the internal space of the transport liner. For example, Japanese Patent Laid-Open No. 59-2 discloses a technical means in which the liner is inflated to restrain and support the nuclear fuel rods, and the liner can be easily inserted and removed.
It was developed as disclosed in Publication No. 08495.

(Problem to be Solved by the Invention) However, in order to transport a nuclear fuel assembly using the above technical means, a liner is inserted between the nuclear fuel rods of the nuclear fuel assembly, and a separate actuating device is installed at the inlet of the liner. The liner is expanded by connecting and filling the internal space of the liner with fluid, and in order to maintain the expanded shape of the liner, it is necessary to seal the inlet of the liner, making the insertion process complicated. There is a problem with workability.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a method for transporting a nuclear fuel assembly that facilitates insertion and extraction operations and shortens operation time.

[Structure of the invention]

(Means for Solving the Problems) The method for transporting a nuclear fuel assembly of the present invention includes providing a transport liner in which a liquid having a property of cooling and solidifying is sealed in an internal space, and transporting the nuclear fuel of the nuclear fuel assembly into the transport liner. The transportation liner is inserted between the rods, the inserted transportation liner is cooled, the liquid sealed in the transportation liner is cooled and solidified, and the transportation liner maintains a shape corresponding to the space between the nuclear fuel rods.
The transport liner is configured to restrain and support nuclear fuel rods.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a liner for transporting nuclear fuel assemblies used in the method for transporting nuclear fuel assemblies of the present invention, and this liner body 10 is molded using a highly elastic material such as polyethylene or rubber. There is. The insertion dimension of the insertion portion 11 of the liner main body 10 is set to be larger than the dimension between the fuel rods. Inside the insertion section 11, a second
As shown in the figure, a space 12 is formed that extends in the insertion direction. The space 12 is filled with a liquid 13 that has the property of solidifying without decreasing its volume when cooled.

Next, the effect will be explained.

To transport a nuclear fuel assembly to its destination, the liner is first brought to room temperature so that the liquid contained within it remains liquid. A liner containing liquefied liquid is inserted between the fuel rods of a nuclear fuel assembly. The liner main body 10 is
Since it is flexible at room temperature, the liquid sealed in the space 12 of the liner body 10 moves in the space 12 extending in the insertion direction, as shown in FIG. It is smaller than the inter-rod dimension, and the liner body 10 can be inserted between the fuel rods without any difficulty. After the liner body 10 is inserted into a predetermined position between the fuel rods, the nuclear fuel assembly is stored in a transport container (not shown) equipped with refrigeration equipment, and the transport container is frozen. When the liner body 10 is frozen, the liquid 13 in the space 12 solidifies in that state,
The fuel rods are fixed by the liner body 10, and the nuclear fuel rods are restrained and supported.

In this state, the liner body 10 inserted between the fuel rods
The spacer maintains a shape corresponding to the gap between the fuel rods and restrains and supports the nuclear fuel rods, suppressing the vibration of the nuclear fuel rods in the nuclear fuel assembly, allowing the spacer and the fuel rods to slide, and causing contact friction scratches on the fuel rods. There's nothing to do.

When the transportation of the nuclear fuel assembly to the destination is completed, the transportation container is thawed, and the liquid inside the liner body 10 is also thawed. As a result, the liquid sealed in the space of the liner body 10 becomes liquid, and the liner body 10 can be easily extracted from the nuclear fuel assembly.

〔Effect of the invention〕

As described above, according to the present invention, a transport liner is provided in which the inner space is filled with a liquid having a property of cooling and solidifying, and the transport liner is inserted between the nuclear fuel rods of a nuclear fuel assembly. By cooling the transportation liner and cooling and solidifying the liquid sealed in the transportation liner, the transportation liner maintains a shape that corresponds to the space between the nuclear fuel rods, and the transportation liner restrains and supports the nuclear fuel rods. Therefore, the transportation liner can be easily inserted between the fuel rods and withdrawn from between the fuel rods, and there is no need to prepare other equipment for insertion and extraction, so the work time is reduced compared to conventional ones. This has the effect of reducing the time by about 30%.

[Brief explanation of drawings]

Fig. 1 is an overall view of a transport liner used in the nuclear fuel assembly transport method of the present invention, Fig. 2 is a sectional view of the transport liner, and Fig. 3 is a diagram showing the liner inserted between fuel rods. , FIG. 4 is a diagram showing a nuclear fuel assembly, FIG. 5 is an overall view of a conventional liner for transporting nuclear fuel assemblies, and FIG. 6 is a diagram showing a state in which the liner is inserted between fuel rods. 4... Fuel rod, 10... Liner body, 11...
Insertion part, 12...space, 13...liquid.

Claims (1)

[Claims] A transport liner whose internal space is filled with a liquid that has the property of cooling and solidifying is provided, this transport liner is inserted between the nuclear fuel rods of a nuclear fuel assembly, and the inserted transport liner is cooled to form a transport liner. A method for transporting a nuclear fuel assembly, characterized in that the transport liner maintains a shape corresponding to the space between the nuclear fuel rods by cooling and solidifying the liquid sealed in the transport liner, and the nuclear fuel rods are restrained and supported by the transport liner. .