Radiation shielding body and portable device capable of mounting the same

Abstract

To provide a radiation shield that attenuates the influence of environmental radiation (background) and enables radiation measurement according to the purpose. [Solution] The radiation shielding body 100 is constructed by tightly connecting a plate group 2, which is made up of multiple stacked plate materials, with releasable fastening members 4 (typically bolts and nuts). The shielding body 100 is composed of a front section 100F and a rear section 100R, with the front section 100F being composed of multiple front plate materials 10 and the rear section 100R being composed of a rear plate material 20. The front plate material 10 has a small diameter hole 12, and the rear plate material 20 has a large diameter hole 22. The small diameter holes 12 and the large diameter holes 22 form a through hole that extends continuously from the front end to the rear end of the shielding body 100. The small diameter holes 12 in the front plate material 10 form a radiation passage through which radiation emitted by the measurement object S passes, and the large diameter hole 22 in the rear plate material 20 forms a radiation measurement device housing section into which a radiation measurement device 40 can be inserted.

Description

[Technical Field]

[0001] This invention relates to a radiation shield that encloses a radiation measuring instrument to attenuate the effects of environmental radiation (background) and enable radiation measurement tailored to the purpose, and to a portable device that can be equipped with the same. [Background technology]

[0002] Patent documents 1 to 3 disclose portable radiation shields. These types of radiation shields were developed for decontamination work following the Great East Japan Earthquake, and have become essential tools for accurately measuring radiation doses on target surfaces such as the ground.

[0003] The use of a radiation shield enables radiation measurement that eliminates the influence of background radiation. Furthermore, even when the background radiation is low, the lower limit of radiation detectability can be set to a low level. This reduces radiation measurement errors and significantly increases the reliability of the measured values. Furthermore, by manipulating the radiation shield, the direction of the small holes in the shield that allow radiation to pass through can be changed, enabling measurements tailored to the purpose, such as determining from which direction the majority of radiation is coming. Furthermore, the use of a radiation shield makes it possible to measure partial radiation in the object being measured.

[0004] The main body of the radiation shield is made of cast lead. It is difficult to ensure dimensional accuracy when casting lead. For this reason, a casting method is used in which an outer shell made of iron or stainless steel is made in advance and molten lead is poured into this outer shell. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Design registration 1455269 [Patent Document 2] Design registration 1485449 [Patent Document 3] Design registration 1502524 Summary of the Invention [Problem to be solved by the invention]

[0006] Problems with the manufacture of conventional radiation shields include the need for special casting techniques and equipment, which increases manufacturing costs and lead times, as well as the need for skilled craftsmanship to prevent thermal deformation of the outer shell that occurs during casting. Specifically, casting is a one-shot job, and if a casting defect occurs, the shield must be remade from scratch.

[0007] Other problems with conventional radiation shields include: (1) the shields are sometimes roughly handled at radiation measurement sites, and even if they are partially deformed, it is difficult to repair them, so the entire shield must be discarded; (2) even if only a portion of the shield is contaminated, the entire shield must be discarded; and (3) if you want to change the shielding performance of the shield, you have no choice but to purchase a shield that suits your purpose.

[0008] In consideration of the above-mentioned problems, the main object of the present invention is to provide a radiation shield that can solve the problems of the conventional technology. Another object of the present invention is to provide a portable device that can be conveniently carried to the site and that can carry the radiation shield of the present invention. [Means for solving the problem]

[0009] The above technical problem can be solved from one aspect of the present invention. A radiation shielding body that surrounds a radiation measuring device and has a radiation passage through which radiation emitted from a measurement object can pass, the radiation shielding body includes a plate group formed by stacking a plurality of plate materials and a fastening member that releasably connects the plate group; the plate group is composed of a plurality of front plate members that form a front portion facing the measurement object, and a plurality of rear plate members that are located on the opposite side of the front portion and form a rear portion of the radiation shielding body, the front panel has relatively small holes; the rear plate has a relatively large hole for receiving the radiation measuring device; the small hole and the large hole are arranged coaxially to form a through hole extending continuously from the front to the rear of the radiation measuring device; a small hole in the front plate defining the radiation passage; This can be achieved by providing a radiation shielding body in which the large hole in the rear plate constitutes a radiation measuring device receiving section that receives the radiation measuring device in a removable manner.

[0010] According to another aspect of the present invention, the above technical problem is solved by: In the portable device capable of mounting the radiation shield according to the present invention, Multiple wheels and extendable position fixing legs for fixing the portable device in position by extending them; a first area on an upper surface of the portable device for mounting the radiation shielding body and a second area in which a liftable table on which an object to be measured is placed is disposed; a table lifting mechanism for lifting and lowering the table in a space surrounded by a radiation shielding wall is installed inside the portable device; the table lifting mechanism includes a guide rod that guides the up and down movement of the table, and a drive motor that drives the table up and down; This is achieved by providing a portable device in which the table can be raised and lowered to a desired position by the drive motor.

[0011] Other objects and advantages of the present invention will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a side view of an example radiation shield; [Figure 2] FIG. 2 is a plan view of a plate member constituting the front portion of the radiation shield shown in FIG. 1; [Figure 3] FIG. 2 is a plan view of a plate constituting the rear portion of the radiation shield shown in FIG. 1; [Figure 4]1 is a side view of a portable device according to an embodiment of the present invention; [Figure 5] 5 is a plan view of the portable device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] FIG. 1 is a side view of a radiation shielding body 100 according to an embodiment. The radiation shielding body 100 is configured by tightly connecting a plate group 2, which is a stack of multiple plate materials, with releasable fastening members 4. A typical example of the fastening members 4 is a combination of a bolt and a nut. Each plate constituting the plate group 2 can be selected according to the radiation intensity and energy of the measurement target S (an object shown by imaginary lines in FIGS. 4 and 5, which will be described later) that serves as the radiation source, as long as it is made of a material that can reduce the intensity of gamma rays. Examples of selectable materials include lead plates, stainless steel plates, iron plates, and tungsten plates. The plate group 2 may be configured using one type of plate material selected from these, or may be configured using a combination of multiple types of plate materials.

[0014] The radiation shielding body 100 is composed of a front part 100F located on the side of the measurement object S and a rear part 100R located on the opposite side, and has a roughly overall shape of a rectangular parallelepiped with a square cross section. The plate group 2 is composed of a front plate member 10 (FIG. 2) that constitutes the front part 100F and a rear plate member 20 (FIG. 3) that constitutes the rear part 100R. Referring to FIG. 2, the front plate member 10 has a square shape in a plan view and has a small diameter hole 12 with a diameter of 10 mm at its center. Referring to FIG. 3, the rear plate member 20 has a square shape in a plan view with the same dimensions as the front plate member 10 and has a large diameter hole 22 with a diameter of 30 mm at its center. The front plate member 10 and the rear plate member 20 have a total of four bolt insertion holes 30 at their four corners, and the bolts that constitute the fastening members 4 described above are inserted into each bolt insertion hole 30.

[0015] The small diameter hole 12 in the front portion 100F and the large diameter hole 22 in the rear portion 100R form a through hole that extends continuously from the front end to the rear end of the radiation shielding body 100 on the axis Ax (FIG. 1) of the radiation shielding body 100. The large diameter hole 22 in the rear plate member 20 forms a radiation measuring device accommodating section in the rear portion 100R into which the radiation measuring device 40 can be inserted and removed freely. Reference numeral 42 shown in FIG. 1 indicates a cable extending from the rear end portion of the radiation measuring device 40. On the other hand, the small diameter hole 12 in the front plate member 10 forms a radiation passage through which radiation emitted by the measurement target S passes.

[0016] Radiation emitted from the measurement object S enters the inside of the radiation shielding body 100 through the small diameter hole 12 in the front part 100F and is measured by the radiation measuring device 40 inserted into the large diameter hole 22 in the rear part 100R.

[0017] The radiation shielding body 100 shown in Fig. 1 is designed to have the ability to block gamma rays derived from cobalt to 1 / 100. Specifically, the front plate material 10 and the rear plate material 20 are both made of square iron plate material with a thickness of 10 mm and a side length of 330 mm. The front portion 100F is made of 15 plates 10, and the rear portion 100R is made of 20 plates 20. Therefore, the illustrated radiation shielding body 100 can exhibit substantially the same shielding performance as a structure in which the front portion 100F is made of iron material with a thickness of 150 mm and the rear portion 100R is made of iron material with a thickness of 200 mm.

[0018] When the front end portion of the front part 100F becomes radioactively contaminated through use, for example, several front plate members 10 constituting the contaminated portion can be replaced by releasing the fastening members 4, eliminating the need to discard the entire radiation shielding body as in the past.

[0019] Furthermore, lead plates, stainless steel plates, iron plates, and tungsten plates can be prepared in advance as the plates 10, 20 constituting the front section 100F and the rear section 100R, and the number of plates 2 in the front section 100F can be increased on-site depending on the radiation intensity and energy of the object to be measured, or some or all of the plates 2 in the front section 100F and the rear section 100R can be replaced with plates made of a material other than iron. This makes it possible to repair the radiation shielding body 100 on-site, or to transform it into a radiation shielding body 100 that corresponds to the radiation intensity and energy of the object to be measured S. This eliminates the need to obtain multiple types of radiation shielding bodies with different shielding performances.

[0020] 2 and 3, the plate materials 10 and 20 can be manufactured, for example, by simply drilling holes in an available plate material having a desired thickness. Thus, unlike conventional radiation shielding methods that require special casting techniques and equipment and are made by skilled craftsmen, the radiation shielding 100 of the present invention can significantly reduce manufacturing costs and lead times.

[0021] The cross-sectional shape of the radiation shield 100 of the embodiment does not have to be square, and may be circular, hexagonal, octagonal, or the like.

[0022] 4 and 5 show a portable device 200 that is convenient for carrying the radiation shielding body 100 of the embodiment and transporting it to the site to measure radiation emitted from the measurement target S. Fig. 4 is a side view with a portion cut away, and Fig. 5 is a plan view.

[0023] 4, the portable device 200 has four wheels 202 arranged at the four corners, and in addition, it has extendable position fixing legs 204. After the fixed portable device 200 is moved to a predetermined location with the position fixing legs 204 contracted, the position fixing legs 204 can be extended to fix the portable device 200 in place.

[0024] 5, the top surface of the portable device 200 is divided into two areas 210 and 220. The first area 210 is an area for placing the radiation shielding body 100, and the second area 220 is an area for placing the measurement target S.

[0025] A vertically movable lifting table 222 is installed in the second measurement object placement area 220. A measurement object S can be placed on this table 222. Referring to FIG. 4, a shielded space surrounded by a radiation shielding wall 224 is provided inside the portable device 200, and a table lifting mechanism 226 is disposed in this shielded space. The table lifting mechanism 226 includes a guide rod 228 that guides the vertical movement of the table 222 and a drive motor 230, and can electrically raise and lower the table 222 to a desired height position. As a result, after the measurement object S is placed on the table 222, the measurement object S can be positioned at a height position facing the small diameter hole 12 opening in the front end surface of the radiation shielding body 100. The table 222 has a shaft 232 extending downward and is configured as a rotary table that can rotate about the shaft 232.

[0026] The current problem is how to deal with the fuel debris from the Fukushima nuclear power plant. Fuel debris refers to the solidified material that has formed when the nuclear fuel in the reactor melted and mixed with the surrounding metal and concrete. Fuel debris contains both highly radioactive and less radioactive parts.

[0027] The table 222 of the portable device 200 can measure the radiation dose at a plurality of locations on the measurement target S by changing the vertical height position and the rotation position of the axis of rotation. [Explanation of symbols]

[0028] 100 Radiation shield of the embodiment 100F Front of radiation shield 100R Radiation Shield Rear 2 Plate group 4 Fastening components (bolts and nuts) 10 Front plate material 12 Small diameter hole 20 Rear plate material 22 Large diameter hole 30 Bolt insertion hole S Measurement object 40 Radiation detector 200 Portable equipment 202 Wheels 204 Extendable positioning legs 210 Radiation shielding installation area 220 Area for placing the measurement object 222 Table for placing the object to be measured 224 Radiation shielding wall surrounding the table lifting mechanism 226 Table lifting mechanism 228 Guide Rod 230 Drive motor 232 Axis extending downward from the table

Claims

1. A radiation shielding body that surrounds a radiation measuring device and has a radiation passage through which radiation emitted from a measurement object can pass, the radiation shielding body includes a plate group formed by stacking a plurality of plate materials and a fastening member that releasably connects the plate group; the plate group is composed of a plurality of front plate members that form a front portion facing the measurement object, and a plurality of rear plate members that are located on the opposite side of the front portion and form a rear portion of the radiation shielding body, the front panel has relatively small holes; the rear plate has a relatively large hole for receiving the radiation measuring device; the small hole and the large hole are arranged coaxially to form a through hole extending continuously from the front to the rear of the radiation measuring device; a small hole in the front plate that defines the radiation passage; A radiation shield characterized in that the large hole in the rear plate member forms a radiation measuring device storage section that receives the radiation measuring device in a removable manner.

2. The radiation shield according to claim 1 , A radiation shield, wherein the front plate and the rear plate have the same outer shape.

3. The radiation shield according to claim 2, A radiation shield, wherein the front plate member and the rear plate member have a square outer shape.

4. The radiation shield according to claim 1 , The fastening member is formed by a combination of a bolt and a nut, The radiation shield, wherein the front plate member and the rear plate member have bolt insertion holes formed therein through which bolts are inserted.

5. The radiation shield according to claim 1 , A radiation shield, wherein each of the plates constituting the group of plates is made of one type of plate material selected from lead plates, stainless steel plates, iron plates, and tungsten plates, or a combination of multiple types of plate materials.

6. A portable device capable of mounting the radiation shield according to any one of claims 1 to 5, Multiple wheels and extendable position fixing legs for fixing the portable device in position by extending them; a first area on an upper surface of the portable device for mounting the radiation shielding body and a second area in which a liftable table on which a measurement object is placed is disposed; a table lifting mechanism for lifting and lowering the table in a space surrounded by a radiation shielding wall is installed inside the portable device; the table lifting mechanism includes a guide rod that guides the up and down movement of the table, and a drive motor that drives the table up and down; The portable device, wherein the table can be raised and lowered to a desired position by the drive motor.

7. 7. The portable device according to claim 6, A portable device, wherein the table is configured as a rotary table that can rotate on an axis.

Images