Radiation shielding structure

Abstract

To provide a radiation shielding structure that utilizes a vertical structural slit capable of suppressing deterioration of radiation shielding performance.SOLUTION: A radiation shielding structure disclosed herein has a vertical structural slit 10 formed therethrough, the vertical structural slit consisting of: an inner vertical slit 11, or a vertical slit formed through an additional wall section 4 additionally installed along a pillar 1 at a corner on a radiation room side where walls 2, 3 intersect with each other with the pillar 1 in between to extend from the additional wall section 4 inside the radiation room to the pillar 1; and two branched vertical slits 12, 13, or vertical slits branching from the inner vertical slit 11 at the pillar 1 to extend along side surfaces of the pillar 1 to the outside of the radiation room.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a radiation shielding structure using vertical structural slits that can suppress a decrease in radiation shielding performance. [Background technology]

[0002] Conventionally, structural slits have been provided to prevent stress concentration in components caused by providing earthquake-resistant walls (see, for example, Patent Document 1). Rooms in which treatment using strong radiation is performed (such as linac rooms) need to be surrounded on all four sides by thick concrete walls (for example, walls with a thickness of t = 1,400 mm) for radiation shielding, but naturally, stress concentration also occurs in these walls. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 167853 / 1983 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to alleviate the above-mentioned stress concentration, measures such as installing earthquake-resistant walls on the periphery of the same floor as the linac room, increasing the strength of the materials around the linac room, or cutting off the boundary between the linac room and the surrounding framework have been taken. However, there is a problem that the construction time is longer than that of a pure steel structure.

[0005] The problem of stress concentration could be solved if structural slits could be provided in the walls of the linac room. However, conventional slit materials are made of polyethylene and the like, which have low radiation shielding capabilities, so providing structural slits would reduce the radiation shielding performance.

[0006] The present invention has been made in consideration of the above, and has an object to provide a radiation shielding structure using vertical structural slits that can suppress a decrease in radiation shielding performance. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the present invention is characterized in that an additional wall section is installed along a pillar at the corner on the radiation room side of the part where the walls intersect via a pillar, and a vertical structure slit is formed consisting of an inner vertical slit, which is a vertical slit extending from inside the radiation room of the additional wall section to the pillar, and two branch vertical slits, which are vertical slits that branch into two on the pillar side of the inner vertical slit and each extend along the circumferential surface of the pillar to the outside of the radiation room.

[0008] In the present invention, the inner vertical slit is formed obliquely with respect to the radiation arrival direction.

[0009] In the present invention, in the above-mentioned invention, the inner vertical slit is formed by a plurality of partial inner vertical slits bent with respect to the horizontal direction.

[0010] In the present invention, in the above-mentioned invention, the branch vertical slit is formed of a plurality of partial branch vertical slits bent with respect to the horizontal direction.

[0011] In the present invention, in the above-mentioned invention, the two branched vertical slits are formed on the same vertical plane and in each wall.

[0012] In addition, the present invention is characterized in that, in the above-mentioned invention, the thickness of the pillar is smaller than the thickness of the wall, and the thickness of the corner side of the intersection of each wall is made into the additional wall portion. Effect of the Invention

[0013] According to the present invention, the deterioration of radiation shielding performance can be suppressed. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a plan cross-sectional view showing a radiation shielding structure using vertical structural slits. [Diagram 2] FIG. 2 is a plan sectional view showing a radiation shielding structure using a vertically structured slit according to the first modification. [Diagram 3] FIG. 3 is a diagram showing a vertical structure slit according to the second modification. [Figure 4] FIG. 4 is a diagram showing a vertical structure slit according to the third modification. [Diagram 5] FIG. 5 is a diagram showing a vertical structure slit according to the fourth modification. [Figure 6] FIG. 6 is a diagram showing a simulation result of a radiation dose distribution for the radiation shielding structure using the vertical structure slit shown in FIG. [Figure 7] FIG. 7 is a diagram showing the dependence of radiation dose on the thickness of concrete for the radiation shielding structure using the vertical structural slits shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A radiation shielding structure according to an embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a plan sectional view showing a radiation shielding structure using a vertically structured slit 10. As shown in Fig. 1, the vertically structured slit 10 separates the column 1 from the wall 2 and the column 1 from the wall 3 in the vertical direction by branched vertical slits 12, 13 which are gaps extending in the vertical direction (±Z direction) provided between the column 1 and the wall 2 and between the column 1 and the wall 3, thereby preventing stress concentration.

[0016] Here, since the portion where the walls 2 and 3 intersect via the pillar 1 has low radiation shielding performance in the direction of the radiation source R inside the radiation room, an additional wall section 4 is installed at the corner on the radiation room side by being added along the pillar 1. The horizontal cross-sectional shape of the additional wall section 4 shown in Figure 1 is an isosceles vertical triangle, with the right-angled apex facing the pillar 1 and the two equal sides joined to the inside of each wall 2 and 3.

[0017] Therefore, the vertical structural slit 10 also forms an inner vertical slit 11 in the additional wall section 4, which separates the column 1 from the wall 2 and the column 1 from the wall 3. The inner vertical slit 11 is formed in a direction that equally divides the base from the right-angled apex of an isosceles triangle that appears in the horizontal cross-sectional shape of the additional wall section 4. The radiation source R may be present on an extension of the inner vertical slit 11.

[0018] As a result, the vertical structure slit 10 forms an inner vertical slit 11 extending from the inside of the radiation chamber of the added wall section 4 to the pillar 1, and also branches into two on the pillar 1 side of the inner vertical slit 11, forming two branched vertical slits 12 and 13 that each extend along the circumferential surface of the pillar 1 to the outside of the radiation chamber.

[0019] In addition, the vertical structural slit 10 may not only provide a gap between the pillar 1 and the wall 2 and between the pillar 1 and the wall 3, but may also be filled with a radiation shield such as polyethylene. In this case, the inner vertical slit 11 and the two branch vertical slits 12 and 13 may be made of the same material or different materials.

[0020] Here, radiation incident on the inner vertical slit 11 is attenuated within the slit, and since the inner vertical slit 11 and the branch vertical slits 12, 13 are bent and joined, less of the radiation that passes through the inner vertical slit 11 heads toward the branch vertical slits 12, 13. As a result, the radiation is attenuated, and radiation shielding performance can be maintained.

[0021] <Variation 1> Fig. 2 is a plan cross-sectional view showing a radiation shielding structure using the vertical structure slit 10 of Modification 1. As shown in Fig. 2, the inner vertical slit 11a of Modification 1 corresponding to the inner vertical slit 11 is formed obliquely with respect to the radiation arrival direction. This reduces the amount of radiation incident on the inner vertical slit 11a, and the radiation shielding performance can be further maintained.

[0022] <Variation 2> Fig. 3 is a plan cross-sectional view showing a radiation shielding structure using the vertical-structure slit 10 of Modification 2. As shown in Fig. 3, the partial inner vertical slits 11b and 11c of Modification 2 corresponding to the inner vertical slit 11 are bent and joined with respect to the horizontal direction. Moreover, the partial inner vertical slit 11b on the radiation source R side is formed obliquely with respect to the radiation direction, similar to Modification 1. This further attenuates the radiation incident on the partial inner vertical slits 11b and 11c, making it possible to maintain the radiation shielding performance.

[0023] <Variation 3> Fig. 4 is a plan cross-sectional view showing a radiation shielding structure using the vertical structure slit 10 of the modified example 3. As shown in Fig. 4, two branch vertical slits 12a, 13a corresponding to the two branch vertical slits 12, 13, respectively, are formed on the same vertical plane and formed in each wall 2, 3. Even if the two branch vertical slits 12a, 13a are not formed between the column 1 and each wall 2, 3, stress concentration between the column 1 and each wall 2, 3 is prevented. In addition, since the inner vertical slit 11 and the branch vertical slits 12a, 13a are perpendicular to each other, radiation is attenuated and radiation shielding performance can be maintained.

[0024] <Variation 4> Fig. 5 is a plan cross-sectional view showing a radiation shielding structure using a vertical structure slit 10 of modified example 4. As shown in Fig. 5, the pillar 1 of modified example 4 is a cylinder, and its thickness (diameter) is smaller than the thickness of the walls 2, 3. Therefore, the thickness of the corner side of the intersection of the walls 2, 3 is treated as the thickness of the additional wall portion 4. Therefore, in modified example 4, the additional wall portion 4 is not provided.

[0025] In this case, the inner vertical slit 11d corresponding to the inner vertical slit 11 is formed on the corner side of the intersection of the walls 2 and 3, and partial branch vertical slits 12b and 13b, which are short branch vertical slits perpendicular to the inner vertical slit 11d, are branched and connected to the inner vertical slit 11d, and partial branch vertical slits 12c and 13c are bent and extended and connected to each partial branch vertical slit 12b and 13b along the cylindrical pillar 1. As a result, in the fourth modification, when the thickness of the pillar is smaller than the thickness of the wall, there is no need to provide an additional wall portion 4, and the vertical structure slit 10 is branched and connected along both sides of the pillar 1 as in the embodiment and the first to third modifications, so that radiation is effectively attenuated and stress concentration between the pillar 1 and each wall 2 and 3 can be prevented.

[0026] <Radiation attenuation analysis> Figure 6 is a diagram showing the results of a simulation of radiation dose distribution for a radiation shielding structure using the vertical slit 10 shown in Figure 1. In Figure 6, the gap width of the vertical slit 10 is set to 3 cm, the thickness of the walls 2 and 3 is 50 cm, and the pillar 1 is a square pillar of 50 cm x 50 cm. Note that while the length of the equal sides of the added wall (thickness of the concrete) is "t" cm in Figure 1, in Figure 6, t = 100 cm.

[0027] As shown in FIG. 6, the radiation dose is effectively attenuated by the pillar 1 and the walls 2 and 3, and the radiation shielding function is maintained.

[0028] Fig. 7 is a diagram showing the dependency of the radiation dose on the concrete thickness t for the radiation shielding structure using the vertical structure slit 10 shown in Fig. 1. As shown in Fig. 7, the radiation dose is effectively attenuated with an increase in the concrete thickness t.

[0029] Note that the configurations illustrated in the above embodiments and modifications are merely functional schematics and do not necessarily have to be physically configured as illustrated. In other words, the distribution and integration of each device and component is not limited to that illustrated, and all or part of them can be functionally or physically distributed and integrated in any unit depending on various usage conditions, etc. [Explanation of symbols]

[0030] 1 Pillar 2,3 Wall 4. Additional wall section 10 Vertical structure slit 11, 11a, 11d Inner vertical slit 11b, 11c Partial inner vertical slit 12, 12a, 13, 13a Branch vertical slit 12b, 12c, 13b, 13c Partial branch vertical slit R radiation source

Claims

1. An additional wall portion is provided along the pillar at the corner on the radiation room side of the portion where the wall intersects with the pillar, A radiation shielding structure characterized in that a vertical structure slit is formed consisting of an inner vertical slit, which is a vertical slit extending from inside the radiation chamber of the added wall section to the pillar, and two branch vertical slits, which are vertical slits that branch off on the pillar side of the inner vertical slit and each extend along the circumferential surface of the pillar to outside the radiation chamber.

2. The radiation shielding structure according to claim 1 , wherein the inner vertical slit is formed obliquely with respect to a direction in which radiation arrives.

3. The radiation shielding structure according to claim 1 , wherein the inner vertical slit is formed by a plurality of partial inner vertical slits bent with respect to the horizontal direction.

4. 2. The radiation shielding structure according to claim 1, wherein the branched vertical slit is formed by a plurality of partial branched vertical slits bent with respect to the horizontal direction.

5. The radiation shielding structure according to claim 1 , wherein the two branching vertical slits are formed on the same vertical plane and in each wall.

6. 2. The radiation shielding structure according to claim 1, wherein the thickness of the pillars is smaller than the thickness of the walls, and the thickness of the corners of the intersections of the walls is used as the additional wall portions.

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