JPS59208500A - Radiation shield putty composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a radiation shielding putty-like composition.

In order to prevent the leakage of radiation from various voids such as the voids where electric wires and piping pass through the chamber walls and vessel walls of nuclear power plants, lead wool has traditionally been filled directly into the voids, or The practice is to pack the materials into bags and fill the voids with them. However, according to this method, the work of filling the voids with lead hairs is complicated, and the filling rate of lead hairs into the voids is only about 50%, so it is difficult to seal the voids airtight. Can not. On the other hand, curable resin compositions containing lead powder are also known. It is generally known that the radiation shielding effect is proportional to the areal density defined as the product of the density and thickness of the filled shielding material. Since the content of is limited, even though it is relatively easy to apply to voids, the radiation shielding property is still insufficient.

Moreover, it cannot be easily removed after curing, which may cause problems when adding electric wires or piping after curing.

The present invention has been made in order to solve the above-mentioned problems in shielding radiation. Not only is it highly effective, it is putty-like so it can be easily applied to any shape of void.
It is an object of the present invention to provide a radiation-shielding putty-like composition that has excellent shape retention after application and is non-curing, so that it can be easily removed as needed after application.

The radiation-shielding putty-like composition according to the present invention contains 500 to 4,000 parts by weight of an inorganic powder having a density of 5 or more per 100 parts by weight of a binder made of a natural or synthetic viscous liquid or semi-solid.
part by weight and 0.1 to 50 parts by weight of fiber, and has a density of 4 or more.

The binder used in the present invention is not particularly limited, and various binders may be used as long as it is a natural or synthetic viscous organic or inorganic liquid or semi-solid that can hold the resulting composition in the form of a putty. can be used, but usually
The viscosity at 25° C. is preferably 104 centistokes or more, and the immiscible consistency specified in Section 5.3.4 of JIsK222o-1980 is preferably 100 or more.

When the viscosity at 25° C. is less than 10 centistokes, it is difficult to form a putty-like composition with self-shape retention, while when the consistency is less than 100 centistokes, it is difficult to form a putty-like composition that has sufficient radiation shielding effect. This is because, when a certain amount of inorganic powder is contained in a composition, the composition is difficult to be putty together. Preferably, the binder has a viscosity at 25° C. of 105 centistokes or higher and a consistency of 150 or higher, particularly preferably a viscosity of 2×10” centistokes or higher and a consistency of 20 centistokes or higher.
It is in the range of 0 or more.

As such a viscous binder, for example, viscous liquid or semi-solid generally known as grease, certain liquid or semi-solid organic or inorganic polymers, and mixtures of these with the above-mentioned grease are preferable. used.

Grease is generally a natural or synthetic oily dispersion medium, i.e., a base oil with a thickening agent dispersed therein, and is a viscous liquid or semi-solid substance at room temperature. It is called grease. The above base oil is
For example, petroleum oils such as transformer oil, spindle oil, cable oil, insulating oil, and machine oil; natural oils such as rosin oil, castor oil, olive oil, and whale oil; and synthetic polymer oils such as polybutene, chlorinated paraffin, and polyethylene glycol. Examples of thickeners include fatty acids barium, strontium, zinc, lead, cadmium, potassium,
In addition to metal soaps that are metal salts of sodium, calcium, lithium, aluminum, etc., bentonite, silica gel, copper phthalocyanine, etc. are used as non-soap soaps. Of course, mixtures of any two or more of the above-mentioned thickeners may also be used.

Specific examples of such greases include soap-based greases such as sodium soap grease, calcium soap grease, lithium soap grease, aluminum soap grease, barium soap grease, and non-B soap greases. As examples, bentonite grease, silica gel grease, etc. can be mentioned, and lithium soap grease, aluminum soap grease, bentonite grease, silica gel grease, etc. are particularly preferably used because they have excellent shape retention properties of the composition.

However, in addition to the above, generally known greases, such as the grease described in "Lubricating Oil and Grease" by Hiroshi Horiguchi (published by Sankyo Publishing, 1972), pages 402 to 419, can also be used.

Specific examples of the organic or inorganic polymer include petroleum hydrocarbon oil, olefin polymerized oil such as polybutene, polyalkylene gellicol oil, halogenated hydrocarbon oil such as chlorinated paraffin, liquid chloroprene rubber, liquid butadiene rubber, Examples include liquid rubbers such as liquid nitrile rubber, silicone oil, and water glass.

The radiation shielding putty-like composition according to the present invention contains 500 to 4000 parts of inorganic powder per 100 parts by weight of the binder.
parts by weight, preferably 800 to 2500 parts by weight. This inorganic powder functions as a radiation shielding material. Therefore, if the content of this inorganic powder is too small, the radiation shielding effect will be low, while if the content is too large, the resulting composition will not have a putty-like appearance. A particularly preferred range is 1000 to 2000 parts by weight.

Further, the density must be 5 or more, and particularly preferably 7 or more. Any inorganic powder can be used as long as it has good compatibility with the binder, but powders made of metals or metal oxides are usually used. Specifically, for example, lead, zinc, iron, zirconium, copper, oxides of these, and various other compounds are used, but lead and lead oxide powders are particularly preferably used because they have a density of 9 or more. .

In addition, it is preferable that these powders have a smaller particle size in order to contain them in a large amount in the composition, but for example, according to JIS
A particle size that allows 100% passing through a 60-mesh standard sieve can be used.

Preferably, a powder having a particle size that passes through a 100 mesh sieve by about 80% is used. In addition, if a mixture of coarse particles that pass through a coarse sieve of less than 100 mesh 100% and fine particles that pass at least 90% of a fine sieve of 100 mesh or more is used, these inorganic powders can form a form in which fine particles are filled between the coarse particles. Since the inorganic powder is dispersed in the composition, a larger amount of the inorganic powder can be contained in the composition.

Further, in order to maintain the shape of the radiation shielding putty-like composition for a long period of time after applying it to a desired location, the radiation shielding putty-like composition according to the present invention contains 0.1 to 50 parts by weight of fibers per 100 parts by weight of binder, preferably 0.1 to 50 parts by weight of fibers. Contains 1 to 20 parts by weight. Here, the fibers may be inorganic fibers or organic fibers, but for the reasons mentioned above, the fibers have a diameter of 100 μm or less, particularly in the range of 0.05 to 50 μm, and an average length of 0.1 to 50++n. It is desirable to have one. As such fibers, both inorganic fibers and organic fibers can be used. Examples of inorganic fibers include asbestos, rock wool, glass wool, carbon fibers, and metal fibers such as iron and copper. Examples of the fibers include, but are not limited to, polyamide fibers, fluororesin fibers, and phenolic fibers. If the composition contains too much fiber, the composition will no longer have a putty-like appearance, which is not preferable.

In addition to the binder, inorganic powder, and fibers described above, the putty-like composition according to the present invention can be made flame retardant by containing an appropriate amount of other fillers, such as a flame retardant such as aluminum hydroxide, if necessary. It is also possible to add a coloring agent, and it is also possible to add a coloring agent to the surface.

The radiation-shielding putty-like composition according to the present invention is not limited in its manufacturing method, but can be obtained, for example, by uniformly kneading the required components using a conventional method such as a kneader or roll.

The radiation shielding putty-like composition of the present invention having the above composition usually has a softness defined in JIS A 5752 in the range of 1 to 25 (In) at room temperature, preferably 3 to 25 (In).
The density is in the range of 18, and the density is 4 or more, preferably 6 or more.

In the present invention, plasticizers for vinyl chloride resins such as dioctyl phthalate, and compounding agents for other synthetic resins and rubbers can also be included as long as the above-mentioned physical properties are satisfied.

The radiation shielding putty-like composition according to the present invention contains an inorganic powder such as a metal or metal oxide powder with a high content and high density, and has an excellent radiation shielding effect and has a high density. Although the composition is large, it has a putty-like appearance, making it easy to apply to voids of any shape that may cause radiation leakage.Moreover, it is non-curing, so it does not harden after application. No post-processing required. Furthermore,
Once applied, it retains its shape for a long time, but can be easily removed if necessary. In addition, almost no loss on heating was observed.

The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples in any way. It should be noted that, as described above, it is known that the radiation shielding effect of a composition is generally proportional to its areal density, so the density is only mentioned in the Examples.

The components shown in the Examples table were kneaded with a roll to prepare a radiation-shielding putty-like composition according to the present invention. All of these contain a large amount of lead, lead oxide powder, and other metal oxide powder, and as shown in the table, although they have a high density composition,
It has moderate softness and good self-shape retention, and therefore has excellent versatility and workability, as well as non-curing properties and easy removal after construction.

Among the putty properties listed in the table, self-shape retention was evaluated as follows. That is, the composition is thoroughly kneaded by hand to form a mixture of about 1ω.
The ease of making a cube was evaluated, and the stability of the resulting cube form was evaluated on a five-point scale.

S: It has good cohesiveness as a putty, has moderate softness, and can be easily molded into a cube, and
The cubic form is also held very stably.

E: The consistency as a putty is slightly inferior to that of S, but the moldability into a cube and its stability are also excellent.

G...Has a consistency as a putty, and also has a cubic 1 The moldability and stability into a body are also sufficient for practical use.

F: It has a certain consistency as a putty and can be formed into a cube, but this cube loses its shape even by a slight external force.

P: The fluidity is excessively large and the putty does not form a cohesive structure, making it difficult to form into a cube.

In addition, non-curing property was evaluated as good if the change in softness after leaving the composition at room temperature for one month was 3.0 or less.

2 (Note) Tll JIS K 2220-1980 5.3.
Immiscible consistency specified in Section 4 240-280 (0.1 m
) Viscosity at +2125°C: Approximately 2 x 10 centistokes Viscosity at +3125°C: Approximately 1.2 x 10 Centistokes Viscosity at 14125°C: Approximately 4.5 x 10 centistokes (5) Kevlar dry pulp (DuPont) (6) Average particle size: 350 mesh sieve 96.5% pass (7) Average particle size 98% pass (8
) Average particle size 350 mesh sieve 93% bath (9) Average particle size 350 mesh sieve 98% bath 00) 195
Patent applicant for weight loss after heating at ℃ for 3 hours Agent for Dainichi Nippon Electric Cable Co., Ltd. Patent attorney Ittsu Makino Department 4 633-

Claims (1)

[Claims] +11 For 100 parts by weight of a natural or synthetic viscous liquid or semi-solid binder, 500 to 4000 parts by weight of an inorganic powder with a density of 5 or more and 0.1 to 50 parts by weight of fibers. A radiation shielding putty-like composition comprising: a radiation shielding putty having a density of 4 or more. (2) The radiation shielding putty-like composition according to claim 1, wherein the binder has a viscosity at 25° C. of 104 centistokes or more and a consistency according to JIS K 2220-1980 of 100 or more.