JP3003656U - Neutron shielding duct device - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a neutron shielding duct device capable of efficiently shielding neutrons, particularly fast neutrons. [Structure] The neutron shielding duct device of the present invention comprises pure polyethylene or boron that can shield neutrons in a cylindrical duct sleeve that penetrates through a radiation shielding wall of a nuclear facility without blocking gas flow. It is characterized in that a screw made of polyethylene is installed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a neutron shielding duct device used for a radiation shielding wall of a nuclear facility that is required to shield neutrons.

[0002]

[Prior art]

 Nuclear facilities are surrounded by radiation shielding walls, which have the ability to prevent radiation from leaking outside, as they contain or handle radioactive materials inside. In addition, a duct for air supply and exhaust is provided through this radiation shield wall, and this duct is also required to have the same radiation leakage prevention capability as the radiation shield wall. The device is installed.

Conventionally, as a device for preventing leakage of radiation in a duct provided through a wall that shields radiation, for example, Japanese Patent Laid-Open No. 59-176700 discloses at least one made of a dense metal. Disclosed is a device characterized in that a screw having a threaded screw member is filled in a duct so that a gas is allowed to flow but radiation is sufficiently attenuated during transmission or reflection. The publication also describes that the screw is formed by casting iron, steel, stainless steel, lead or the like.

Further, Japanese Laid-Open Patent Publication No. 62-274300 discloses a tubular duct casing and a bent circumferential flow passage for allowing a fluid to pass through the duct casing, so that the duct casing is completely disconnected. Disclosed is a radiation shielding duct characterized by comprising a screw made of a radiation shielding material which covers an area and has an axial center extending in the axial direction of the duct casing. There is also a statement that it is composed of a metal material.

Further, in Japanese Utility Model Laid-Open No. 3-85598, a cylindrical duct sleeve and a radiation shielding screw housed in the duct sleeve are formed by integral casting of cast iron. The radiation shielding duct device is disclosed.

The radiation shielding duct devices disclosed in these publications are mainly those in which the duct and the screw body or the screw body are cast and formed by metal, and are mainly intended to shield γ rays. there were. This screw body does not hinder the flow from the outside to the inside of the radiation shielding wall or vice versa, and since the γ-rays try to go straight, they are attenuated in the process of transmission or reflection transmission in the screw body, It acts to prevent the leakage of γ rays in the duct.

Further, as a radiation leakage prevention device for the purpose of shielding γ rays and / or neutron rays, Japanese Utility Model Laid-Open No. 5-62898 discloses a duct that penetrates a radiation shielding wall of a nuclear facility, Installed in the duct, it has a screw shape that does not hinder the straight movement of γ-rays and does not hinder the flow of gas, and has a hollow inside, and the filling that fills the hollow inside of the screw. A material having a large neutron shielding effect, a substance having a large γ-ray shielding effect, or a substance having a large neutron and γ-ray shielding effect. A radiation leakage prevention device in a characteristic nuclear facility is disclosed. Further, the publication describes that the screw body having a hollow portion is made of a metal having a high effect of shielding γ rays from high density, for example, a cast product such as SCS13 or FC. Further, the publication discloses a liquid containing a large amount of hydrogen as a material for the filler, a paraffinic substance such as pure polyethylene, or a silicon-based liquid substance obtained by adding a heat-resistant metal oxide and a boric acid compound to silicon rubber. is doing.

[0008]

[Problems to be solved by the device]

 However, in the above-mentioned Japanese Utility Model Laid-Open No. 5-62898, a high density metal casting is used as a material that interferes with the line of γ-rays in the screw body. It is not possible to fabricate a screw body with a complicated shape having a hollow part for filling, and at present the neutron shielding duct device aimed only at shielding neutrons, especially fast neutrons, has not been developed. is there.

Therefore, an object of the present invention is to provide a neutron shielding duct device capable of efficiently shielding neutrons, particularly fast neutrons.

[0010]

[Means for Solving the Problems]

 That is, the neutron shield duct device of the present invention is a pure polyethylene or a boron-added polyethylene that can shield neutrons without blocking the flow of gas in a cylindrical duct sleeve that penetrates through the radiation shield wall of a nuclear facility. It is characterized by installing a screw consisting of.

[0011]

[Action]

 The neutron shielding duct device of the present invention is mainly aimed at shielding fast neutrons, and is made of pure polyethylene or boron-added polyethylene whose content of hydrogen atoms effective for decelerating fast neutrons is the highest rank among resins. Is what you use. These pure polyethylene or boron-added polyethylene cannot be manufactured into a screw with a complicated shape by pouring into a formwork, etc., and the workability is inferior to that of metal casting. As described above, there is no example of being used as a screw for a duct device, which is expected to have a considerably long dimension corresponding to the thickness of the radiation shielding wall of a nuclear facility.

According to the present invention, the screw is cut out from a bar of pure polyethylene or boron-added polyethylene as a single piece by cutting, or the screw is divided into a plurality of screw members constituting the pure polyethylene or boron. It was completed based on the finding that a screw made of pure polyethylene or boron-added polyethylene, which is effective for decelerating fast neutrons, can be easily manufactured by cutting out from the added polyethylene plate material by cutting and combining a predetermined number of them. It is a thing.

[0013]

【Example】

 Hereinafter, the neutron shielding duct device of the present invention will be further described with reference to examples. Example FIG. 1 is a view showing an embodiment of a screw used in the neutron shielding duct device of the present invention. In Fig. 1, the screw (1) is based on four threads having four screw blades (2), but the screw (1) is not limited to four threads, and has a neutral shielding ability and the like. The desired number of threads can be taken into consideration. Also, the pitch of the screw blades (2) is not particularly limited and can be a desired pitch.

The screw (1) is made of pure polyethylene or polyethylene with boron added. Here, the screw (1) is cut out from a bar material having a predetermined size of pure polyethylene or boron-added polyethylene as an integrated body by cutting, or by combining a screw member (3) as shown in Fig. 2 to a predetermined size. It can be provided as a screw (1). The screw member (3) can be cut out from a plate material of pure polyethylene or boron-added polyethylene by cutting. When connecting a certain number of screw parts (3) to form a screw (1), as shown in FIGS. 3 and 4, at least two pin insertion holes are formed on the connecting surface (4) of the screw member (3). (5) is installed, and using a pin (6) made of the same material as the screw member (3), connect a predetermined number of screw members (3) to prevent the screw member (3) from shifting its shape. You can In addition, although the example in which two screw members (3) are connected is described in FIG. 3, the number of connected members is not limited to two, and in the case of connecting three or more members, an intermediate portion may be used. The pin insertion holes (5) may be installed on both connecting surfaces of the screw member (3) located.

In addition, by further adding boron to pure polyethylene forming the screw, decelerating fast neutrons by the action of polyethylene to change them into thermal neutrons, and capturing the thermal neutrons by the action of boron, it is particularly excellent. It can exert the effect of shielding fast neutrons. Here, the amount of boron added is about 15% by weight or less, preferably about 10% by weight or less. If the amount of boron added exceeds 15% by weight, it is difficult to manufacture a bar or plate, which is not preferable.

FIG. 5 shows an embodiment of an example of installation of the neutron shielding duct device of the present invention on the radiation shielding wall of a nuclear facility. In FIG. 4, the nuclear radiation shielding wall (7) is usually concrete. Etc., and a cylindrical duct sleeve (8) is provided so as to penetrate the radiation shielding wall (7). The screw (1) having the above-described configuration and having an outer shape substantially the same as the inner diameter of the duct sleeve (8) is inserted into the duct sleeve (8). The length of the screw (1) is approximately equal to the thickness of the radiation shielding wall. Next, the screw (1) is prevented from moving in the duct sleeve (8), or the screw (1) is composed of a plurality of screw members (3), the connection part by the pin is fixed. Therefore, the neutron shielding duct device of the present invention can be installed on the radiation shielding wall by fixing both ends of the screw (1) by any means.

[0017]

[Effect of device]

 According to the neutron shielding duct device of the present invention, since the screw made of pure polyethylene or boron-added polyethylene is installed in the duct sleeve penetrating the radiation shielding wall of the nuclear facility, the inside of the radiation shielding wall is The external and external air can freely flow, while the fast neutrons try to go straight, so they are attenuated in the process of transmitting or reflecting through the screw, preventing the leakage of neutral atoms in the duct sleeve. it can.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of a screw constituting a neutron shielding duct device of the present invention.

FIG. 2 is a diagram showing one embodiment of a screw member that constitutes a screw.

FIG. 3 is a cross-sectional view of a screw member showing one embodiment for connecting the screw members.

FIG. 4 is a view showing a connecting surface of the screw member shown in FIG.

FIG. 5 is a diagram showing an embodiment of an example of installation of the neutron shielding duct device of the present invention on a radiation shielding wall of a nuclear facility.

[Explanation of symbols]

 1 Screw 2 Screw Blade 3 Screw Member 4 Connection Surface 5 Pin Insertion Hole 6 Pin 7 Radiation Shielding Wall 8 Duct Sleeve

Claims (4)

[Scope of utility model registration request] 1. A screw made of pure polyethylene or boron-added polyethylene capable of shielding neutrons is installed in a cylindrical duct sleeve provided penetrating a radiation shielding wall of a nuclear facility without blocking gas flow. A neutron shielding duct device characterized by the following. 2. The neutron shielding duct device according to claim 1, wherein the screw is formed by cutting a rod made of pure polyethylene or boron-added polyethylene into a screw shape. 3. A screw having a predetermined size by cutting a plate material of pure polyethylene or boron-added polyethylene into a screw member, and connecting a predetermined number of the obtained screw members. Item 1. The neutron shielding duct device according to item 1 or 2. 4. At least two connecting surfaces of the screw member.
The neutron shielding duct device according to claim 4, wherein a pin structure is provided at one place.