JPH1164583A - Housing method of spent fuel and spent fuel housing body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform a sealing work by remote control, to ensure the sealing property, and to facilitate the opening when necessary by heating and melting a seal metal adhered to the connecting part of the mouth part of a metallic container, and sealing the connecting part by resolidification of the seal metal. SOLUTION: A connecting part (screwing part) 2a is arranged on the mouth part 2 of a metallic container 1 to vertically divide the metallic container 1. A middle melting point metal is preliminarily adhered to the surface of the connecting part by metal plating. A spent fuel X is charged in the metallic container 1, the connecting part 2a is screwed, and preliminarily adhered seal metal is heated and melted by an induction heating coil arranged around it. The heating is stopped in the molten state followed by cooling and the connecting part 2a is sealed by resolidification of the seal metal. A series of these works is executed by remote control. When it is required to take out the spent fuel X from the metallic container 1, the metallic container 1 is opened by heating the connecting part 2a by the induction heating coil to melt the seal metal, and separating the connecting part 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for storing spent fuel and a spent fuel container.

[0002]

2. Description of the Related Art Technical example 1: Japanese Unexamined Patent Publication No. 07-1 / 1990 relates to a technology for storing spent nuclear fuel (hereinafter referred to as spent fuel).
JP 20589 and Technical Example 2: JP-A-08-0295
No. 92 is proposed.

[0003] In Technical Example 1, in a metal storage container,
After the spent fuel assembly is loaded in a state where a space is formed between the fuel cell and the side wall, and the space around the spent fuel assembly is filled with the thermally conductive particles, the metal container is sealed. In Technical Example 2, a support spacer having heat conductivity is attached to the inside of a metal container body, and a spent fuel assembly is loaded into a fuel storage hole of the support spacer. After that, the lid is welded to make the spent fuel assembly a sealed spent fuel container.

[0004]

However, the technical examples 1 and 2 employ a technique of sealing a metal container by forming a welded portion, so that it is necessary to remove spent fuel in the near future. In such a case, the labor for opening the work becomes enormous, and the handleability tends to be impaired.

[0005] The present invention has been made in view of the above-mentioned circumstances, and achieves the following objects. Perform sealing work efficiently by remote control. Ensure sealing. To be able to open when needed and to facilitate opening.

[0006]

A spent fuel is loaded into a metal container, and the sealing metal adhered to the joint at the mouth of the metal container is melted by heating. For sealing is performed by re-solidifying the sealing metal. A medium melting point metal such as Cd is employed as the sealing metal. As the joining portion at the mouth of the metal storage container, one having a screwed portion or a step portion is employed. The inside of the metal container is filled with a solid filler between the spent fuel and the spent fuel to promote heat transfer. As the solid filler, alumina particles having high thermal conductivity in the form of granules or pellets and having excellent heat resistance are applied. In addition, an inert gas such as dry nitrogen gas is filled in the metal container as needed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method for storing spent fuel and a spent fuel container according to the present invention will be described.
This will be described with reference to FIGS. In each of these figures, reference symbol P is a spent fuel container, X is spent fuel, 1 is a metal container, 2 is a mouth, 3 is a solid filler, and 4 is an induction heating coil.

The spent fuel X is, for example, the above-mentioned spent nuclear fuel, but may be a radioactive waste, a storage body thereof, a solidified body, or the like.

The metal container 1 is made of, for example, stainless steel material. A suspending portion 1a for suspending the whole is disposed at an upper position, and a plurality of the same type are stacked at a lower position. Skirt portion 1b is arranged.

The mouth 2 has a joint (screwed portion) 2
a, and the metal storage container 1 is divided vertically by the joint 2a. In addition, C
A medium melting metal such as d is applied by metal plating, welding, vapor deposition, application of powder, or the like.

The solid filler 3 is disposed between the inner wall of the metal container 1 and the spent fuel X, and is described in the above-mentioned technical example 1: Japanese Patent Application Laid-Open No. 07-120589. According to the technology, for example, alumina particles having an appropriate particle diameter are applied.

A method for storing the spent fuel X will be described below. Inside the metal container 1, spent fuel X
2 is screwed as shown in FIG. 3 to the joint 2a to which the sealing metal m is previously attached, as shown in FIG. Around the induction heating coil 4, the sealing metal m is heated and melted, the heating is stopped in a state where the sealing metal m is melted, and the sealing metal m is re-solidified by cooling thereafter. The joint 2a is sealed. These series of operations (operations) are performed by remote control, and the inside of the metal container 1 is filled with an inert gas such as dry nitrogen gas as needed. When the sealing metal m is Cd, its melting point: 321 ° C.
Heated to a higher temperature.

In the case of the spent fuel container P having a structure as shown in FIG. 1, the decay heat of the radioactive element contained in the spent fuel X mainly passes through the solid filler 3 having good thermal conductivity. The heat is transmitted to the outer wall of the metal container 1 and is removed by air or the like around the outer wall of the metal container 1. The radiation emitted from the spent fuel X is attenuated by passing through the layer of the solid filler 3.

On the other hand, when it becomes necessary to pull out the spent fuel X from the metal container 1, the joint 2a of the metal container 1 is heated by the induction heating coil 4 to re-seal the sealing metal m. This is performed by melting and flowing down, or by separating the joint 2a while keeping the sealing metal m in a molten state. Therefore, the spent fuel container P can be opened when necessary, and the opening operation can be easily performed.

[Other Embodiments] In the joint portion 2a of the mouth portion 2 shown in FIGS. 1 to 3, a screw screw structure is adopted. However, the present invention has a plurality of steps. In addition, those in which the sealing metal m is disposed at the joint portion and those in which fastening means such as bolts are disposed at that time are also included.

[0016]

According to the storage method and the spent fuel container according to the present invention, the following effects can be obtained. (1) The sealing metal adhered to the joint at the mouth of the metal container is heated and melted, and the joint is sealed by re-solidifying the sealing metal, thereby facilitating remote operation and sealing work. Can be performed efficiently. (2) The joint can be closed by re-solidification of the sealing metal, and the sealing performance can be ensured. (3) By heating the joint to melt the sealing metal again, it is possible to open the seal when needed and easily take out the spent fuel.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an embodiment of a spent fuel storage method and a spent fuel storage body according to the present invention.

FIG. 2 is a front cross-sectional view showing a state of division of a joining portion in FIG.

FIG. 3 is a front cross-sectional view showing a state of sealing of a joint of FIG. 1;

[Explanation of symbols]

 P Spent fuel container X Spent fuel 1 Metal container 1a Suspended portion 1b Skirt 2 Port 2a Joint (screwed portion) 3 Solid filler 4 Induction heating coil m Sealed metal

Claims (4)

[Claims] 1. A metal container (1) having a spent fuel (X) loaded therein and a sealing metal (m) attached to a joint (2a) of a mouth portion (2) of the metal container. ) Is heated and melted, and the joint is sealed by re-solidification of the sealing metal. 2. The method for storing spent fuel according to claim 1, wherein the sealing metal (m) is a medium melting point metal. 3. A sealed metal (m) is interposed at a joint (2a) of a mouth portion (2) of a metal container (1), and the spent fuel is placed inside the metal container. After loading (X), the sealing metal at the joint is heated and melted,
A spent fuel container, wherein a joint is formed in a sealed state by re-solidification of a sealing metal. 4. The spent fuel container according to claim 3, wherein the joint (2a) of the mouth portion (2) of the metal container (1) is a screw threaded portion.