JP2017173260A - Interior material, structure with the interior material, and method for suppressing radioactivation of foundation using the interior material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress radioactivation of a foundation.SOLUTION: An interior material A1 includes a first neutron absorption layer 1 and a neutron absorption layer 3, which contain 3-90 parts by weight of a neutron absorber to 100 parts by weight of synthetic resin.SELECTED DRAWING: Figure 1

Description

  The present invention is used in, for example, radiation facilities such as radiation medical facilities and research facilities, neutron utilization facilities, etc., and prevents the generation of radioactive waste by suppressing the activation of the concrete underneath these facilities, Interior materials that reduce air dose and reduce unnecessary exposure of facility users such as patients, medical workers, researchers, etc., structures provided with the interior materials, and radiation of the ground using the interior materials The present invention relates to a method for suppressing crystallization.

In recent years, facilities that handle neutron beams, such as radiation medical facilities such as PET facilities and BNCT facilities, accelerator facilities, and inspection facilities using neutrons, are increasing.
In these facilities, if the floor, wall, or ceiling is activated by the use of neutrons, there is concern about the exposure of medical workers, patients, workers, etc. Moreover, when these facilities are demolished when they are aged, a large amount of radioactive waste is generated, and there is a possibility that the cost for disposal becomes enormous.
Therefore, as a measure for suppressing activation, a concrete plate containing a neutron absorber, a concrete material with a reduced Na content, and a neutron shielding method are known (see Patent Documents 1 to 3).

Japanese Patent No. 4532447 JP 2015-10826 Japanese Patent No. 4643193

  However, since the activation of the base generally occurs only near the surface on the indoor side, it is uneconomical to use an expensive special concrete material or the like for the entire base as in the prior art. Moreover, in the said prior art, the burden concerning construction work increases and it does not have the designability and functionality calculated | required by interior material.

In view of such problems, the present invention has the following configuration.
An interior material including a neutron absorption layer, wherein the neutron absorption layer includes 3 to 90 parts by weight of a neutron absorber with respect to 100 parts by weight of a synthetic resin.

  Since the present invention is configured as described above, activation of the ground can be suppressed.

(A) is sectional drawing which shows an example (Example 1-6) of the interior material which concerns on this invention, (b) is sectional drawing which shows another example (Example 7). (A) is principal part sectional drawing of the structure which comprised the interior material of Fig.1 (a), (b) is principal part sectional drawing of the structure which comprised the interior material of FIG.1 (b). It is a table | surface which shows the mixing | blending of a neutron absorption layer about Examples 1-7 and Comparative Examples 1-3. It is a table | surface which shows the result of an evaluation test about Examples 1-7 and Comparative Examples 1-3. It is a table | surface which shows the result of activation experiment about Example 6 and Comparative Example 1. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The interior material A1 shown in FIG. 1A is a multilayer structure in which a first neutron absorption layer 1, a base material 2, a second neutron absorption layer 3, and a design layer 4 are laminated in order from the deep layer side. Configured.

  Each of the 1st and 2nd neutron absorption layers 1 and 3 rolls the compound formed by kneading | mixing a synthetic resin, a neutron absorber, etc. by calendering. An inorganic filler, other additives, etc. are blended with the compound as necessary.

  Examples of the synthetic resin include polyvinyl chloride, ethylene-vinyl chloride copolymer, propylene-vinyl chloride copolymer, vinyl chloride-acrylic resin copolymer, vinyl chloride-urethane copolymer, vinyl chloride-vinylidene chloride. Examples thereof include vinyl chloride resins such as copolymers and vinyl chloride-vinyl acetate copolymers, and olefin resins such as polyethylene and polypropylene. These may be used alone or in combination of two or more. Among these synthetic resins, polyvinyl chloride is preferable in terms of processability, workability, and cost.

  As the neutron absorber, for example, a compound containing an element that absorbs thermal neutrons such as lithium, boron, samarium, and gadolinium is used. Of these, boron compounds such as boron nitride, boron carbide, boric acid and perovskite are preferably used, and hexagonal boron nitride is preferable in consideration of moldability, damage to processing equipment, and activation suppression performance.

The blending amount of the neutron absorber is preferably 3 to 90 parts by weight with respect to 100 parts by weight of the synthetic resin. When the blending amount is less than 3 parts by weight, sufficient activation suppressing performance cannot be obtained, and when it is more than 90 parts by weight, the workability at the time of production is remarkably lowered.
Further, the content of the neutron absorbing material per unit area is preferably 0.1 to 3 kg / m ² . When the content is less than 0.1 kg / m ^2, sufficient activation suppression performance cannot be obtained. If it is more than 3 kg / m ² , the processability during production is significantly reduced.

In addition, as the inorganic filler, a substance different from the neutron absorber, such as calcium carbonate, is used within a range that does not affect the activation suppression performance.
This inorganic filler improves the adhesiveness between the adhesive and the first neutron absorption layer 1 when the interior material A1 is bonded to the base, and is preferably 1 to 100 parts by weight of the synthetic resin. ~ 10 parts by weight is blended.
As other examples of the inorganic filler, silica, clay, magnesium hydroxide and the like can be used.

  In addition, as additives, plasticizers, heat stabilizers, antibacterial agents, light stabilizers, ultraviolet absorbers, flame retardants, antistatic agents, lubricants, colorants, etc., have the necessary physical properties according to the intended use. In order to give, it can mix | blend suitably.

The substrate 2 is formed by molding a large number of fibers into a net or sheet.
Examples of the material for the substrate 2 include cotton, hemp, polyester, acrylic, nylon, carbon fiber, glass and other organic fibers, and woven fabrics and nonwoven fabrics made of inorganic fibers.
This base material 2 can be laminated | stacked between each layer as a lowermost layer (in other words, the deepest layer or the backmost layer), or as an intermediate | middle layer, and selects a material and a lamination position according to a use application. Can do. In particular, in applications where dynamic load resistance, dent resistance, and dimensional stability are important, it is preferable that the base material 2 is composed of inorganic fibers such as glass and the base material 2 is laminated as an intermediate layer. The thickness t2 of the substrate 2 is not particularly limited, but is usually set within a range of 0.01 to 1 mm.

  As other examples other than the illustrated example, the first and second neutron absorption layers 1 and 3 can be applied to any of the layers constituting the interior material A1, and in particular, the interior material A1 is When used as a flooring, the first and second neutrons are used in order to reduce the effect of the neutron absorption performance on durability and design because the surface of the flooring is worn by walking for a long time. It is preferable to apply the absorbing layers 1 and 3 to the back layer or intermediate layer which is not the outermost layer. And it is preferable to arrange the design layer 4 or other transparent layer described later on the outermost surface layer.

The first neutron absorption layer 1 and the second neutron absorption layer 3 in the illustrated example are laminated on both sides of the base material 2 therebetween.
The thicknesses t1 and t3 of the first neutron absorbing layer 1 and the second neutron absorbing layer 3 are set to be substantially the same, and in a preferred example of the present embodiment, each is set to about 0.8 mm (total 1.6 mm). Yes.
The first neutron absorption layer 1 is heat-sealed to one surface of the substrate 2 by, for example, laminating.
Similarly, the second neutron absorbing layer 3 is heat-sealed to the other surface of the substrate 2 by, for example, laminating.

Designs such as patterns and designs are printed on the surface of the second neutron absorption layer 3 in order to impart design properties. This design is covered with the design layer 4.
The design layer 4 is a layer made of a transparent or translucent synthetic resin, and is laminated on the surface of the second neutron absorption layer 3 by, for example, laminating.
A preferable thickness t4 of the design layer 4 is set within a range of 0.2 mm to 1 mm.

  In addition, as other means for imparting design properties to the surface of the second neutron absorption layer 3, without printing the design, an aspect in which a printed layer or a colored layer is laminated as the design layer 4, various natural fibers, An aspect in which a design imparting material such as synthetic fiber, wood powder, or resin chip is added to the second neutron absorption layer 3 or the design layer 4, and the surface of the interior material A1 (or A2) is provided with unevenness by, for example, embossing Or the like.

The thickness of the interior material A1 having the above-described configuration can be appropriately selected depending on the construction site and application, but is preferably 0.2 to 5 mm.
For example, when the interior material A1 is used as a flooring material, the total thickness T1 can be set to the thickness of a flooring material that is usually used. As a particularly preferable aspect, the thickness T1 is set to 1.5 to 5 mm. Set.
If the thickness T1 is set to be less than 1.5 mm, it will be easily affected by the shape of the ground surface, such as fine irregularities, and the post-construction aesthetics will be damaged, and the durability against walking and caster running will be inferior. There is a risk of on the other hand. When the thickness T1 is set to be thicker than 5 mm, an unnecessary weight increase may cause a decrease in workability when the interior material A1 is laid, an increase in cost, and the like.

Next, the interior material B1 shown in FIG.
The interior material B1 is configured in a single-layer structure including only a single third neutron absorption layer 5.
The configuration, material, and the like of the third neutron absorption layer 5 are the same as those of the first and second neutron absorption layers 1 and 3 described above.
The thickness T2 of the interior material B1 can be set to 1.5 to 5 mm similarly to the interior material A1, and the interior material B1 in the illustrated example constitutes a tile material having a thickness of about 5 mm.
In addition, also in this interior material B1, it is possible to provide the design and design layer 4 which were mentioned above as needed.

The interior materials A1 and B1 having the above-described configuration can be manufactured by appropriately combining known techniques such as calendar molding, extrusion molding, injection molding, and laminating. Among these, calender molding is preferable because a wide sheet can be efficiently produced and the base material 2 and the design layer 4 can be easily laminated.
And in construction of interior material A1, B1, it is possible to use auxiliary materials, such as the conventional construction method and an adhesive agent.

Next, the structures A2 and B2 including the interior materials A1 and B1 configured as described above will be described.
A structure A2 shown in FIG. 2A includes the interior material A1 having the above-described configuration and a base C covered with the interior material A1.
Similarly, the structure B2 illustrated in FIG. 2B includes the interior material B1 having the above-described configuration and a base C covered with the interior material B1.
These structures A2 and B2 can be, for example, radiation facilities such as radiation medical facilities and research facilities, facilities using neutrons, PET facilities, accelerator facilities, inspection facilities using neutrons, and the like. And the foundation | substrate C is the floor surface of the said facility, for example, is formed with concrete or mortar.
The interior materials A1 and B1 cover part or all of the surface of the base C, and are attached to the surface with the adhesive layer 6 interposed therebetween.
The adhesive layer 6 is composed of a primer (undercoat paint) applied to the base C surface, an adhesive applied to the dried surface of the primer, and the like.
As the primer, for example, SP primer U manufactured by Ron Seal Industry can be used.
Further, the adhesive preferably conforms to JIS A 5536, and for example, Ron cement power epoch manufactured by Ron Seal Industry can be used.

  Next, the result of an evaluation test is demonstrated about interior material A1, B1 of the said structure (refer FIGS. 3-5 (Tables 1-3)).

FIG. 3 (Table 1) shows the composition of the neutron absorbing layer used in Examples 1 to 6 and Comparative Examples 1 to 3. The materials used for each formulation are as follows.
Synthetic resin: Polyvinyl chloride resin (PVC) Degree of polymerization 1000, specific gravity: 1.4
Plasticizer: Dioctyl phthalate (DOP), specific gravity: 0.99
Thermal stabilizer: Barium-zinc metal soap, powder, specific gravity: 1.15
Inorganic filler: calcium carbonate, specific gravity: 2.7, Mohs hardness: 3
Neutron absorber A: hexagonal boron nitride, average particle size: 8 μm, specific gravity: 2.27, Mohs hardness: 2
Neutron absorber B: Boron carbide, average particle size: 13.7 μm, specific gravity: 2.51, Mohs hardness: 14
Base material: Glass cloth, thickness approx. 0.2mm, basis weight approx. 3 / cm x lateral approx. 3 / cm

<Preparation of specimen>
First, each mixture (compound) shown in FIG. 3 (Table 1) was melt-kneaded and then formed into a single-layer sheet by calendering using a calender roll at a temperature of 185 ° C.
In Table 1, the single-layer sheet-like material of the compositions of Examples 1 to 6 is configured as the first neutron absorption layer 1 or the second neutron absorption layer 3, and each has a thickness t1 (or t3). ) Is about 0.8mm.
In Table 1, the single-layer sheet material of the composition of Example 7 is configured as the third neutron absorption layer 5 and has a thickness T2 of about 5 mm.
Further, in Table 1, each of the single-layer sheet materials of the compositions of Comparative Examples 1 to 3 has a thickness of about 0.8 mm.

  Further, a mixture of 100 parts by weight of a vinyl chloride resin, 35 parts by weight of a plasticizer, 3 parts by weight of a heat stabilizer, and 20 parts by weight of a filler was formed into a single-layer sheet by calendar molding similar to the above. This single-layer sheet-like material is configured as the design layer 4 and has a thickness t4 of about 0.4 mm.

The above-described respective sheet-like materials and the base material 2 were sequentially laminated by thermal fusion to obtain the interior materials of Examples 1 to 7 and Comparative Examples 1 to 3.
Examples 1 to 6 and Comparative Examples 1 to 3 are each a laminated body having a cross-sectional structure similar to that of the interior material A1 described above (see FIG. 1A), and has a total thickness T1 of about 2 mm. Formed.
In addition, since the 1st neutron absorption layer 1 and the 2nd neutron absorption layer 3 fill the mesh | network of the base material 2 as demonstrated previously, the whole thickness T1 does not become the total value of thickness t1-t4 of each layer. There is a case.

  Example 7 is a single-layer body having a cross-sectional structure similar to that of the interior material B1 (see FIG. 1B), and was formed in a tile shape having an overall thickness T2 of about 5 mm.

<Evaluation of molding processability>
The moldability shown in FIG. 4 (Table 2) is obtained by melting and kneading each mixture (compound) blended in FIG. 3 (Table 1) with two rolls at 185 ° C. to form a single layer sheet having a thickness of about 0.8 mm. The results of evaluating the moldability during molding are shown.
In Table 2, OΔx in the row of moldability indicates the following state, respectively.
○: Good kneading workability and sheet formability.
Δ: A slight hardness is felt during the kneading operation, but sheet molding is possible.
X: The compound is very hard and the kneading work is difficult. It is difficult to form a sheet due to poor penetration of the compound into the roll gap.

<Evaluation of thermal neutron absorption>
Evaluation of the thermal neutron absorbability shown in FIG. 4 (Table 2) is based on Examples 1 to 7 and Comparative Examples 1 to 3 having a cross-sectional structure of the interior material A1 or the interior material B1 (see FIGS. 1A and 1B). Was carried out by radiation simulation analysis using particle and heavy ion transport calculation code PHITS (Particle and Heavy Ion Transport Code System). PHITS is one of the general-purpose Monte Carlo calculation codes for particle and heavy ion transport, and is a highly reliable analysis system that is also used for applications for approval of radiation facilities.
In Table 2, ◎ ○ △ × in the thermal neutron absorbability row indicates that the ratio of the thermal neutron transmission amount when Comparative Example 1 is 1 is in the following range.
◎: 0.5 or less ○: 0.5 to 0.8
Δ: 0.8 to 1.0
×: 1.0 or more

<Bending flexibility evaluation>
For evaluation of the bending flexibility shown in FIG. 4 (Table 2), each of Examples 1 to 6 and Comparative Examples 1 to 3 having the cross-sectional structure of the interior material A1 (see FIG. 1A) is 100 mm in length. A test piece having a width of 25 mm was prepared and used.
This bending flexibility is applied by applying the test method of JIS K 7106, and the distance between fulcrums (20mm) and load (1.2Lbs) of the Orzen-type bending stiffness tester is constant, and it is indicated when folding at 60 ° in the corner direction. The value was evaluated.
In Table 2, ◯ Δ × in the bending flexibility row indicates that the ratio (unit:%) when the load of the testing machine is 100% is in the following range. It can be evaluated that it is so flexible that this figure is low.
○: 50 or less △: 51-80
×: 81 or more

<Adhesion evaluation>
For the evaluation of the 90-degree peel adhesive strength shown in FIG. 4 (Table 2), each of Examples 1 to 6 and Comparative Examples 1 to 3 having the cross-sectional structure (see FIG. A test piece of 200 mm × 25 mm wide was prepared and used.
This test is based on JIS K 6854-1, with a primer (SP Primer U made by Ron Seal Industry Co., Ltd.) coated and dried on a mortar board, and an epoxy resin-based two-part adhesive conforming to JIS A 5536 After applying the agent (Lonsea Kogyo Co., Ltd .: Roncement Power Epo) using a special comb iron and taking an open time of 45 minutes, the test piece was pasted and the normal bond strength after 2 days was measured with a tensile tester. It was measured.
In Table 2, “◎” in the 90 ° peel adhesion strength row indicates that the 90 ° peel adhesion strength is in the following range.
◎: 131 (N / 25mm) or more ○: 61-130 (N / 25mm)
Δ: 20-60 (N / 25mm)

As shown in FIG. 4 (Table 2), Examples 1 to 6 had good workability, thermal neutron absorbability, bending flexibility, and 90-degree peel adhesion strength in a well-balanced manner.
Example 7 had a good balance between moldability and thermal neutron absorbability.
In particular, the adhesiveness (Example 6) in which an inorganic filler (calcium carbonate) was blended in the neutron absorbing layer was further improved.

In Comparative Example 1, no neutron absorber was blended, and the thermal neutron absorbability was insufficient.
In Comparative Example 2, a small amount of a neutron absorber (boron nitride) was blended, but the thermal neutron absorbability was insufficient.
In Comparative Example 3, a large amount of a neutron absorber (boron nitride) was blended, and molding processability and bending flexibility were insufficient.

FIG. 5 (Table 3) shows the results of measuring the amount of radioisotope produced by activation experiments.
In this activation experiment, test pieces each having a diameter of 5 cm were prepared and used for Example 6 and Comparative Example 1 having the cross-sectional structure of the interior material A1 (see FIG. 1A).
In this experiment, the test piece is placed on top of a 5 cm diameter and 5 cm high regular concrete cylinder, a neutron generator is installed above the test piece, and the neutron generator is directed to the surface of the test piece. Then, a certain amount of thermal neutrons are irradiated, and then the amount of the two types of radioisotopes Na-24 and Mn-56, which are the main causes of the exposure generated on the above-mentioned ordinary concrete (cylinder), is measured using a germanium semiconductor detector. And measured.
The neutron generator generates a proton beam emitted from an accelerator (cyclotron) by colliding with a beryllium target, and decelerates and releases the energy to thermal neutron energy by a polyethylene moderator.
The amount of thermal neutron irradiated by the neutron generator was 1.9 × 10 ⁻⁵ n / sec / cm ² and the irradiation time was 2 hours.

  The result of the activation experiment is as shown in FIG. 5 (Table 3), and Example 6 according to the present invention is more effective than the case where the conventional flooring material (Comparative Example 1) is constructed. It was confirmed that the generation amount can be greatly reduced to about 1/2, and it has the effect of suppressing the activation of the ground concrete.

Therefore, according to the interior materials A1 and B1, the structures A2 and B2 and the activation suppression method described above, it is possible to easily achieve the activation suppression of the ground concrete, which is impossible with the conventional interior material, and consequently In addition to preventing exposure of facility users and the like, it is possible to reduce the cost of disposal by suppressing the generation of radioactive waste during the demolition of buildings and the like.
Furthermore, according to the interior materials A1 and B1 of the present embodiment, the design properties required for the interior material can be improved by the structure of the design layer 4 and the like.

  In the interior material A1, the thicknesses t1 and t3 of the first neutron absorption layer 1 and the second neutron absorption layer 3 are substantially the same. However, as another example, the two thicknesses t1 and t3 are different. It is also possible.

  Moreover, as an aspect which is not shown in figure, the aspect which excluded the design layer 4 from interior material A1 (refer FIG. 1 (a)), the aspect which provided the base material 2 between each adjacent neutron absorption layer while providing three or more neutron absorption layers Or the like.

  Moreover, according to the said embodiment, as an especially preferable aspect, although interior material was comprised as a flooring, as another example of this interior material, wallpaper, a wall board material, a waist board material, a ceiling material, etc. are comprised. Is also possible.

  Further, the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention.

1: First neutron absorption layer 2: Base material 3: Second neutron absorption layer 4: Design layer 5: Third neutron absorption layer 6: Adhesive layer A1, B1: Interior materials A2, B2: Structure

Claims (7)

  An interior material including a neutron absorption layer, wherein the neutron absorption layer includes 3 to 90 parts by weight of a neutron absorber with respect to 100 parts by weight of a synthetic resin. The interior material according to claim 1, wherein the content of the neutron absorber is 0.1 to 3 kg / m ² .   The interior material according to claim 1 or 2, wherein the thickness is 0.2 to 5 mm.   The interior material according to any one of claims 1 to 3, wherein the neutron absorption layer contains an inorganic filler.   The interior material according to any one of claims 1 to 4, wherein a base material is laminated as an intermediate layer or a lowermost layer with respect to the neutron absorption layer.   A structure comprising the interior material according to any one of claims 1 to 5 and a base covered with the interior material.   A method for suppressing activation of a base, comprising sticking the interior material according to any one of claims 1 to 5 to the base.

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