JPH06109894A - Shielding container - Google Patents

Abstract

PURPOSE:To lower the temperature of the inside of a shielding body, to moderate a temperature gradient of the inside and the outside and thereby to improve the soundness of the shielding body by a construction wherein a plurality of closed flow pipes extending in the direction of a tube are disposed in a shielding material and a coolant (water) is made to circulate therethrough. CONSTITUTION:A coolant piping 1 is installed along iron plates 3 on the outside and inside so that it surrounds a shielding material 2, and the upper and lower parts of the piping are joined so that a long loop-shaped pipeline is formed. The piping 1 thus prepared is disposed in a necessary number through the whole peripheral part. When water is filled up in the piping 1 beforehand, a water temperature is made to rise by the inside wall of a shielding container (high-temperature side) being heated, the water is cooled down and made to radiate heat by the outside wall and the temperature lowers. By the repetition of this movement, the temperature of the inside lowers gradually. By lessening a temperature difference between the inside and the outside of the shielding material 2 and moderating thereby a temperature gradient, besides, a crack of the shielding material 2 can be prevented. In addition, a neutron shielding effect by the water can be expected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shielding container for containing a radioactive substance therein, and more particularly to a radiation shielding member for the shielding container which is suitable for alleviating heat generation due to .gamma.

[0002]

2. Description of the Related Art A conventional shield for a high-level radioactive material handling facility is made of concrete as discussed in "Highly radioactive material handling facility and robot", Japan Atomic Energy Society (1983) P183. . The radiation shield of the conventional spent fuel transportation container is a shield of carbon steel and chlorinated polyester resin for the spent fuel, as described in "Thermal Nuclear Power" Vol. 33, No. 2 (1982) P59-60. Is surrounded by.

As a container for radioactive liquid, JP-A-61-161
Japanese Patent No. 144199 is available. This is a structure in which a cooling pipe is spirally wound around the outside of the inner container and the inside of the outer container, and the two are connected. Also, regarding the transportation container for spent fuel,
JP-A-59-182394, JP-A-59-182
There is a 395 publication. In these methods, a cooling pipe is attached to a fin portion provided outside the container to cool from the outside.

[0004]

DISCLOSURE OF THE INVENTION In the prior art,
Since the concrete was used as a shield for high-level radioactive materials, no defect that would affect the shielding effect was generated. However, it is necessary to consider the use of new materials such as ceramics for the shield, considering the compactness of the reactor and the ease of decommissioning. The configuration of the coolant pipe of the transportation shielding container cannot use the forced cooling method using an external pump or the like. Therefore, the natural cooling method must be used.

When these new materials are used, the shield receives radiant heat from the inside, and only the inside has a high temperature, which causes a temperature difference between the inner and outer surfaces and causes a temperature gradient in the shield. In addition, there is a possibility that cracks will occur in the material due to temperature changes due to changes in the position of the heat source (movement of high-level waste liquid, etc.).
The usage method will be limited. Further, as the neutron shielding material of the spent fuel transportation container in the prior art, a material such as a resin having a low melting point and a low thermal conductivity is used, so that special consideration needs to be given to heat removal.

The object of the present invention is to positively move the heat from the inner surface of the shield forming the shield container to the outer surface, thereby lowering the temperature of the inner surface and relaxing the temperature gradient of the inner and outer surfaces to shield the inner surface. The object is to improve the soundness of the body, and also to make it possible to use a material having a lower heat resistance than that of concrete or the like, which is easily cracked by a temperature gradient, as a shielding material.

[0007]

In order to solve the above-mentioned problems, the structure of the shielding container of the present invention is formed by an inner cylindrical member formed by an inner wall plate and an outer wall plate surrounding the inner cylindrical member with a certain interval. A shielded container composed of an outer tubular member, the inner tubular member and the outer tubular member being sealed with a shielding material in a closed container at both ends of which are sealed. A plurality of closed channel pipes are arranged along the inner wall surfaces of the inner tubular member and the outer tubular member so as to extend in the tubular direction and are connected at both ends.

[0008]

In the present invention, when the longitudinal cross section of the shielding container is viewed, the coolant pipe has a vertically long loop shape.
The temperature of the coolant in the flow path on the inner surface (high temperature side) of the container is heated by γ heating or the like and rises. The coolant in the flow path on the outer surface is cooled, descends, and radiates heat to the outside in the meantime. That is, heat removal can be efficiently performed by the natural cooling method. By this action, the temperature of the inner surface of the container gradually decreases, and the temperature gradient of the inner and outer surfaces becomes smaller.
Since such an action simultaneously progresses in each part of the shielding container, the temperature drop in each part also progresses uniformly. It should be noted that Fe, Pb and the like are optimal materials for the γ ray as a shielding material, and water, paraffin and the like are optimal materials for the neutron ray.

[0009]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a partial cross-sectional perspective view of the shield of the first embodiment of the present invention. In FIG. 1, 1 is a coolant pipe, 2 is a shielding material, and 3 is an iron plate. As can be seen from the cut section of the vertical section of the shield, the coolant pipe 1 is installed along the inner wall and the outer wall so as to surround the shield 2, and has a vertically long loop shape connected at the upper and lower portions. Form. A required number of such coolant pipes 1 were arranged over the entire circumference.

If the coolant pipe 1 is filled with water in advance, the inner wall on the high temperature side is heated and the water rises, and the outer wall cools and radiates heat to descend. By repeating this operation, the temperature of the inner surface gradually decreases. It also has the effect of reducing the temperature gradient inside the shield. Furthermore, the neutron shielding effect of water can be expected. The temperature of the radioactive substance contained inside is around 100 ° C.

FIG. 2 is a partial cross-sectional view of the shield of the second embodiment of the present invention. In FIG. 2, 5 is an outer iron plate, 6 is an inner iron plate, 7 is a partition plate, and other elements are the same as those in FIG. In this case, the cross-sectional shape of the coolant pipe 1
By changing the circular cross section of FIG. 1 to a square cross section, the contact efficiency with the wall surface is increased and the cooling capacity is improved. Other effects are similar to those of the first embodiment.

FIG. 3 is a partial cross-sectional perspective view of the shield of the third embodiment of the present invention. In FIG. 3, reference numeral 8 is an iron shield, and other elements are the same as the reference numerals in FIG. In this case, the used fuel transportation container is an example of a container used in a horizontal position. As can be seen from the cut end of the vertical cross section, the coolant pipe 1 has a left and right semicircular closed loop so as to surround the shielding member 2. The heat transfer area per unit area is increased to improve the cooling efficiency. Coolant piping 1
The cross-sectional shape of was rectangular. The effects of this embodiment are exactly the same as those of the first and second embodiments. In addition,
Although water is used as the coolant in the above-mentioned embodiments, the coolant is not limited to this, and a material having a suitable heat transfer property and shielding property can be used.

[0013]

According to the present invention, even if a shielding material having a low heat transfer coefficient such as a new material (ceramic) is used, it is possible to efficiently remove heat. Further, it is possible to prevent the shielding material from cracking by reducing the temperature difference between the inside and outside of the shielding material and relaxing the temperature gradient. By using new materials, etc., it is possible to contribute to the compactification of reactors and the efficiency of decommissioning. Furthermore, when water is used as a coolant, a neutron shielding effect can be expected.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view of a shield according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a shield body according to a second embodiment of the present invention.

FIG. 3 is a partial cross-sectional perspective view of a shield body according to a third embodiment of the present invention.

[Explanation of symbols]

 1 Coolant Pipe 2 Shielding Material 3 Iron Plate 5 Outer Iron Plate 6 Inner Iron Plate 7 Partition Plate 8 Iron Shield

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[Procedure amendment]

[Submission date] October 25, 1993

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

Front Page Continuation (72) Inventor Hiroyuki Handa 3-2-1 Sachimachi, Hitachi City, Ibaraki Prefecture Hitachi Engineering Co., Ltd. (72) Inventor Shigenori Ohno 3-2-1 Sachimachi, Hitachi City, Ibaraki Prefecture Hitachi Engineering Co., Ltd. (72) Inventor Ryuichi Tayama 3-2-1 Sachimachi, Hitachi City, Ibaraki Prefecture Hitachi Engineering Co., Ltd.

Claims (4)

[Claims] 1. An inner tubular member formed by an inner wall plate and an outer tubular member formed by an outer wall plate surrounding the inner tubular member with a certain interval, and both ends of the inner tubular member and the outer tubular member. In a shielding container constituted by a shielding body in which a shielding substance is filled in a closed container having a closed portion, in the shielding body in a cylindrical direction along inner wall surfaces of the inner tubular member and the outer tubular member. A shielded container comprising a plurality of closed flow path pipes which are extended and are connected at both ends. 2. An inner tubular member formed of an inner wall plate and an outer tubular member formed of an outer wall plate surrounding the inner tubular member with a certain distance therebetween, and both ends of the inner tubular member and the outer tubular member. In a shielding container constituted by a shielding body filled with a shielding substance in a closed container of which a part is closed, in a semicircular shape along the outer wall of the inner cylindrical member in the shielding body,
Arranged in a semicircular shape along the inner wall of the outer tubular member, the closed channel pipes connected at both ends on the center line are formed symmetrically,
A shielded container, wherein a plurality of shield containers are arranged in the cylinder axis direction. 3. The shielding container according to claim 1 or 2, wherein the closed channel pipe has a rectangular cross-sectional shape. 4. The shielded container according to claim 1, wherein the substance circulating in the closed channel pipe is water.