JP2012159517A - Radiation shielding body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an assisting tool for measuring radiation emitted by a measurement object by using an available radiation measurement tool while reducing influence of peripheral radiation as far as possible.SOLUTION: A combination of large shielding body 100 and a small shielding body 300 is used for a simple calibration of a cylindrical probe P or a radiation measurement device. An amount of radiation in the environment is measured with the cylindrical probe P or the radiation measurement device. Then a bottom lid 6 is set beneath a shielding body 2 of the large shielding body 100, a sample S is placed in the small shielding body 300 housed in the large shielding body 100, a top lid 4 of the large shielding body 100 is closed, and the cylindrical probe P is inserted into a circular opening 8 of the top lid 4 to measure the amount of the radiation.

Description

  The present invention relates to a radiation shield used for measuring the degree of contamination by radioactivity.

  The accident at the Fukushima nuclear power generation facility caused by the March 2011 Tohoku-Pacific Ocean Earthquake and Tsunami (Great East Japan Earthquake) has resulted in continuing to release a large amount of radioactive material into the environment. As is well known, radioactive contamination over a wide area has become a social problem. One year has passed since the Great East Japan Earthquake, and the national policy was finally decided, and decontamination work in line with this policy has just begun.

  Since the radioactivity is invisible, it is necessary to measure the radiation dose before and after decontamination to clarify the decontamination effect when performing decontamination work. There are various types of radiation measuring instruments on the market. As one form, there is a measuring instrument that has a cylindrical probe and measures the radiation dose of the object or space by holding the probe. it can. Examples of available portable radiation measuring instruments equipped with a probe include the trade names “Multi Radiation Monitor”, “NaI Scintillation Survey Meter”, “GM Pancake Probe (Toyo Medic Co., Ltd.)”, etc. . “RadEye-B20” manufactured and sold by Seiko EG & G Co., Ltd. can be obtained as a portable multipurpose survey meter having a rectangular box-shaped detector as another form.

  Because of the invisible radioactivity, when the decontamination work is contracted and the decontamination work is performed, how much the decontamination target is contaminated, and to what extent is the decontamination effect after decontamination It is desirable to confirm. For this purpose, the above-mentioned radiation measuring instruments for commercial use are used. However, since radioactive contamination is widespread, for example, even if the probe is held over the measurement target (contaminated soil, etc.) There is a problem in that, from the influence, the radiation from the surroundings is detected in addition to the radiation emitted by the radioactive substance attached to the measurement target (decontamination target).

  The present invention has been made in view of such a problem, and as an auxiliary tool for measuring radiation emitted from a measurement object using an available radiation measuring instrument while reducing the influence of radiation from the surroundings as much as possible. An object of the present invention is to provide a radiation shield.

According to the present invention, the above technical problem is
A cylindrical shielding body with its upper and lower ends open;
A ceiling lid provided at the upper end of the shielding body and having an opening in the central portion;
A bottom lid for closing the lower end of the shielding body;
This is achieved by providing a radiation shield having a cross-girder horizontal partition provided at the lower end of the shield body.

  The radiation shield according to the present invention can remove the radiation dose of the concrete surface, roof, etc. by inserting a probe of a measuring instrument into the shielding body with the bottom lid removed or placing the measuring instrument on the shielding body. Measurements can be made while suppressing the effects of radiation. On the other hand, a measurement object (specimen) is placed in a shielded space equipped with a bottom cover, and a probe of the measuring instrument is inserted into the shielded space or the instrument is positioned in the opening of the ceiling cover. Measurements can be made while suppressing the effects of radiation.

  In preferable embodiment of this invention, it has further the cylindrical small shielding body which can be accommodated in said shielding main body. The radiation shielding rate can be increased by placing the small shielding body in the shielding body. In addition, by placing this small shield on the shield body and inserting a probe into this small shield, the radiation dose on the surface to be measured such as the specimen or concrete surface placed in the shield body can be reduced. In addition to measuring, radiation measurement with a portable multipurpose survey meter (above "RadEye-B20") equipped with a cylindrical probe and rectangular box-shaped detector can be performed while suppressing the influence of ambient radiation, and simple calibration Etc. can be performed.

  In a further preferred embodiment of the present invention, a cylindrical additional shield that can be placed on the shield body is further provided, and a pancake-type probe can pass through a peripheral wall of the additional shield. A cutout is provided and the additional shield can be closed by the top lid. By preparing such an additional shield, radiation measurement by “GM Pancake Probe (Toyo Medic Co., Ltd.)” can be performed while suppressing the influence of surrounding radiation.

  According to the present invention, the combination of the radiation shield according to claim 1, the small shield, and the additional shield described above can be applied to all currently available commercial radiation measuring instruments. As well as providing simple calibration.

It is a perspective view of the radiation shielding body of 1st Example. It is the expanded side view which cut | disconnected some suspension handles of the radiation shielding body of 1st Example. It is a front view of the radiation shielding body of 1st Example. It is a rear view of the radiation shielding body of 1st Example. It is a right view of the radiation shielding body of 1st Example. It is a left view of the radiation shielding body of 1st Example. It is a right view of the radiation shielding body of 1st Example, and shows the state which fell the suspension handle. It is a right view of the radiation shield of 1st Example, and shows the state which opened the ceiling cover divided into 2 parts. It is a top view of the radiation shielding body of 1st Example. It is the enlarged plan view which cut | disconnected some suspension handles of the radiation shielding body of 1st Example. It is a bottom view of the radiation shielding body of the 1st example of a state where a bottom lid was equipped. It is a bottom view of the radiation shield of the 1st example of a state where the bottom lid was removed. It is the longitudinal cross-sectional view of the radiation shielding body of 1st Example, and is the figure cut along the AA line of FIG. It is the longitudinal cross-sectional view of the radiation shielding body of 1st Example, and is the figure cut along the CC line of FIG. It is the cross-sectional view of the radiation shielding body of 1st Example, and is the figure cut along the BB line of FIG. It is an expansion perspective view of the principal part of the radiation shield of a modification. It is the top view which extracted the part of the handle of the radiation shield of the modification of FIG. It is the perspective view which extracted the part of the handle like FIG. 17, and is a figure for demonstrating that a handle can rock | fluctuate. It is a figure which shows the state which inserted the finger | toe into the handle shown to FIG. 16, FIG. 17, and lifted the radiation shield of the modification. It is a figure for demonstrating the usage aspect which measures the radiation of a test substance using the shielding body of 1st Example illustrated in FIG. It is a figure for demonstrating the usage aspect which measures radiation, such as a concrete surface and a roof, using the shielding body of 1st Example illustrated in FIG. It is a perspective view of the radiation shielding body of 2nd Example. It is a top view of the radiation shielding body of 2nd Example. It is sectional drawing cut | disconnected along the DD line | wire of FIG. It is a figure for demonstrating the usage aspect which measures radiation, such as a concrete surface and a roof, using the radiation shielding body of 2nd Example. It is a figure for demonstrating the usage aspect which measures the radiation of a test substance with the combination of the radiation shield of 1st Example and 2nd Example. It is a figure for demonstrating the use aspect which mounts the shield of 2nd Example on the shield of 1st Example, measures the radiation of a concrete surface or a specimen, or calibrates a radiation measuring instrument. . It is sectional drawing of the usage pattern which mounts the shielding body of 2nd Example on the shielding body of 1st Example. It is a perspective view of the shielding body of 3rd Example. It is sectional drawing of the usage condition which mounts the shield of 3rd Example on the shield of 1st Example, and measures a radiation.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a perspective view of the radiation shield of the first embodiment, and FIG. 2 is an enlarged side view. Referring to FIGS. 1 and 2, a radiation shield 100 according to the first embodiment includes a cylindrical shielding body 2 opened up and down, a ceiling lid 4 having a shape complementary to the outer contour of the shielding body 2, and The shielding body 2, the ceiling lid 4, and the bottom lid 6 are composed of a radiation shielding material, and in this embodiment, the stainless steel material is used as the outer skin, and the shielding material surrounded by the outer skin is used. Brass or lead is used, and the shielding body 2, the ceiling lid 4, and the bottom lid 6 are made by pouring molten brass and lead into the outer skin. The ceiling lid 4 and the bottom lid 6 have a flat upper surface and a lower surface, and the bottom lid 6 includes a flange 6 a that extends upward on the outer peripheral edge thereof and loosely fits on the outer peripheral surface of the shielding body 2. Yes.

  In this embodiment, the shielding main body 2 has a cylindrical shape, but is not limited thereto. The shielding body 2 may adopt an arbitrary shape such as an ellipse, a quadrangle, or a hexagon as the cross-sectional shape of the outer contour. Moreover, although the internal peripheral surface of the shielding main body 2 also has a circular cross-sectional shape, it is not limited to this. As the cross-sectional shape of the inner peripheral surface of the shielding main body 2, an arbitrary shape such as an ellipse, a quadrangle, or a hexagon may be adopted.

  The ceiling lid 4 has a circular opening 8 penetrating vertically at the center thereof. In this embodiment, the ceiling lid 4 is composed of two ceiling lid halves 10 and 10 obtained by dividing the ceiling lid 4 into two. The ceiling lid 4 may be a separate body from the shielding main body 2, but in this embodiment, each ceiling lid half 10 is connected to the shielding main body 2 by a hinge 12 to open the pair of ceiling lid halves 10, 10. be able to. As a preferred embodiment, it is preferable to provide a hook 14 for connecting the ceiling lid halves 10 and 10 to each other when the shielding body 2 is carried with the ceiling lid halves 10 and 10 closed. Alternatively, the hook 14 may be omitted.

  The bottom cover 6 has a separate structure from the shielding main body 4. Depending on the measurement object, the bottom cover 6 is attached to the shielding main body 2 when the shielding main body 2 is used without the bottom cover 6 as described later. You can choose when to use.

  3 is a front view of the shield 100 according to the first embodiment, FIG. 4 is a rear view, FIG. 5 is a right side view, and FIG. 6 is a left side view. FIG. 7 is a right side view of the shield 100 according to the first embodiment. Referring to FIG. 7, the shield body 2 which is a heavy object is optionally provided with a hanging handle 16, which is convenient to carry, and the hanging handle 16 rotates as shown in FIG. It should be free.

  FIGS. 16-19 shows the radiation shield 200 of a modification. As can be seen from FIGS. 16 to 19, a handle 18 may be provided on the side wall of the shielding body 2. A handle on the side wall of the shielding body 2 as shown in FIGS. 16 to 19 with or without the suspension handle 16 for suspending the shielding body 2 described in the shielding body 100 of the first embodiment described above. 18 is provided. The handle 18 is convenient for adjusting the position of the shielding body 2, and the handle 18 is also conveniently rotatable like the suspension handle 16.

  The shield body 2 may have a long height dimension capable of receiving the above-described radiation measuring instrument cylindrical probe, but the shields 100 and 200 are comparative examples for receiving a part of the probe. Is set to a short height. When the height is set to be long, the circular opening 8 of the ceiling lid 4 may be set to a diameter that can receive a cable connecting the cylindrical probe and the measuring instrument shielding body. Conversely, when the height is set to be short, the opening 8 of the ceiling lid 4 is set to a diameter that can receive the cylindrical probe P as shown in FIGS. 20 and 21 described later. preferable.

  Referring to FIGS. 13, 14, and 15, the shielding body 2 preferably has a cross-shaped horizontal partition 20 at its lower end. Of course, the horizontal partition 20 may be formed separately from the shielding body 2 and the horizontal partition 20 may be installed in the shielding body 2 as necessary.

  Describing how to use the shield 100 of the first embodiment, FIG. 20 shows an example in which the bottom lid 6 is incorporated in the shielding body 2 and a shielding space is formed by the shielding body 2, the ceiling lid 4, and the bottom lid 6. . The specimen S to be measured placed on the plate 22 is placed on the horizontal partition 20 of the shielding body 2, and the cylindrical probe P is inserted into the circular opening 8 of the ceiling lid 4. Thereby, the radiation dose emitted by the specimen S can be measured without being affected by surrounding radiation. It should be noted that even if there is a gap between the circular contour that defines the circular opening 8 of the ceiling lid 4 and the outer contour of the probe P, a large number of empirical data from the inventors of the present application indicates that the measurement results are only different in error. Can be supported from.

  FIG. 21 shows an example of directly measuring contaminated soil or concrete surface. In this application example, the shielding main body 2 is placed on the measurement target surface (the ground or the like) without the bottom lid 6, and the cylindrical probe P is inserted into the circular opening 8 of the ceiling lid 4 to thereby measure the measurement target. The radiation dose on the surface can be measured.

  22-24 shows the radiation shield 300 of 2nd Example. The radiation shield 300 according to the second embodiment has a cylindrical shape, and optionally, a horizontal girder-like horizontal partition 302 is provided at the lower end of the shield 300. The horizontal partition 302 may be formed separately from the shield 300, and the horizontal partition 302 may be incorporated in the shield 300 of the second embodiment as necessary.

  The shield 300 of the second embodiment is preferably set with its outer contour and height so that it can be used together with the shield 100 of the first embodiment described above. That is, the shielding body 300 of the second embodiment is preferably set to have an outer contour and a height dimension that can be accommodated in the shielding body 2 of the shielding body 100 of the first embodiment. Therefore, the shield 300 of the second embodiment will be described as a “small shield”. The shield 100 of the first embodiment that receives the small shield 300 is referred to as a “large shield”.

  In this embodiment, the small shield 300 has a cylindrical shape, but is not limited thereto. The small shield 300 may adopt an arbitrary shape such as an ellipse, a rectangle, or a hexagon as the cross-sectional shape of the outer contour. Moreover, although the internal peripheral surface of the small shielding body 300 also has a circular cross-sectional shape, it is not limited to this. An arbitrary shape such as an ellipse, a quadrangle, or a hexagon may be adopted as the cross-sectional shape of the inner peripheral surface of the small shield 300. However, it has a size that allows the cylindrical probe P to be inserted into the small shield 300, and the lower end opening of the small shield 300 is the same as that of the large shield 100 of the first embodiment described above. It is preferable that the shape and size be complementary to the opening 8 of the ceiling lid 4, but it is not always necessary.

  A method of measuring radiation using the small shield 300 will be described. FIG. 25 shows a case where a small shield 300 is placed on a measurement target surface (such as the ground), and a cylindrical probe P is placed in the small shield 300. The amount of radiation on the measurement target surface can be measured by inserting. An example of this usage can be said to be a usage of the small shield 300 assuming an area with a relatively low radiation dose. Further, by placing “GM Pancake Probe (Toyo Medic Co., Ltd.)” on the small shield 300, the radiation dose on the measurement target surface can be measured.

  FIG. 26 illustrates another usage of the small shield 300. As can be seen from FIG. 26, the effect of shielding radiation from the surroundings can be enhanced by inserting the small shield 300 into the large shield 100. This is the same whether the bottom cover 6 is installed under the shielding main body 2 of the large shield 100 or when the bottom cover 6 is not installed.

  As a usage shown in FIG. 26, a combination of the large shield 100 and the small shield 300 can be used for simple calibration of the cylindrical probe P or the radiation measuring instrument. A specific method of use will be described. First, the radiation dose in the environment is measured with the probe P or radiation measuring instrument. Next, the bottom lid 6 is installed under the shielding main body 2 of the large shield 100, and then the specimen S is placed in the small shield 300 accommodated in the large shield 100, and the ceiling of the large shield 100 is placed. Close the lid 4. As a modification, the sample S may be put in the small shield 300, and then the small shield 300 containing the sample S may be put in the large shield 100 and the ceiling lid 4 may be closed. Further, the bottom cover 6 may be installed below the shielding main body 2 thereafter. Next, a large shield 100 using a non-cylindrical measuring instrument such as “GM Pancake Probe” (sold by Toyo Medic Co., Ltd.) or “RadEye-B20” manufactured and sold by Seiko EG & G Co., Ltd. The amount of radiation that is collimated from the opening 8 of the ceiling lid 4 is measured. Next, the radiation dose coming out from the opening 8 of the ceiling lid 4 of the large shield 100 is measured a plurality of times with another radiation measuring instrument, and the average is obtained and compared with the value obtained with the reference radiation measuring instrument. . Thereby, a simple calibration of the radiation measuring instrument can be performed.

  Another method of using the combination of the large shield 100 and the small shield 300 will be described in detail with reference to FIGS. 27 and 28. First, the shield body 2 is placed on the bottom cover 6, and then the ceiling cover. A small shield 300 is placed on the large shield 100 with 4 closed. Then, the probe P is inserted into the small shield 300 to measure the radiation dose. This is called the background radiation dose. Next, the small shield 300 is removed, the ceiling lid 4 is opened, the specimen S is placed in the shielding body 2 of the large shield 100, and the small shield is placed on the large shield 100 with the ceiling lid 4 closed. 300 is placed, a cylindrical probe P is inserted into the small shield 300 on the large shield 100, and the radiation dose is measured. In the case of a “GM pancake probe” or “RadEye-B20” that is not cylindrical, the “GM pancake probe” or “RadEye-B20” is placed on the small shield 300 and the radiation dose is measured. Thereby, the radiation dose of the specimen S can be measured. Further, an approximate amount of radioactivity such as Bq / Kg can be obtained by calculation using the coefficient of the radiation measuring instrument.

  FIG. 29 shows the shield of the third embodiment, and the shield 400 of the third embodiment is also a modification of the shield 200 of the second embodiment described above. Since the shield 400 of the third embodiment can be suitably applied to a “GM pancake probe” (sold by Toyo Medic Co., Ltd.), it will be referred to as a “pancake probe shield”.

  The shield body 402 of the pancake probe shield 400 has a cylindrical shape, but is not limited thereto. The shielding main body 402 may adopt an arbitrary shape such as an ellipse, a rectangle, or a hexagon as the cross-sectional shape of the outer contour. The inner peripheral surface of the shielding main body 402 has a circular shape, but is not limited to this, and an arbitrary shape such as an ellipse, a quadrangle, or a hexagon may be adopted as a cross-sectional shape of the inner peripheral surface. . However, the pancake probe Ppc is large enough to be inserted into the shield body 402 of the pancake probe shield 400. The shield body 402 has a notch 404 opened upward on its peripheral wall, through which the pancake probe Ppc is set in the shield body 402 (FIG. 30).

  The pancake probe shield 400 also has an upper lid 404. In the embodiment, the upper lid 404 is integrated with the shielding main body 402 via the hinge 410, but the upper lid 404 may have a separate structure from the shielding main body 402. The pancake probe shield 400 also has a hanging handle 408 that can be tilted, but the hanging handle 408 may be omitted.

  Even in this pancake probe shield 400, it can be applied to measure the radiation dose on the surface to be measured independently, similar to the above-described small shield 300 (FIG. 25). Combinations can be used. A specific method of using the combination of the large shield 100 and the pancake probe shield 400 will be described with reference to FIG. 30. The pancake probe shield 400 is placed on the large shield 100. Measured with the pancake probe Ppc installed in the pancake probe shield 400 with the specimen S (bottom lid 6 installed) and the bottom lid 6 removed from the large shield 100 removed. The amount of radiation on the target surface (the ground, etc.) can be measured.

  Also in this pancake probe shield 400, it is preferable to provide a cross-shaped horizontal partition 412 at its lower end. The horizontal partition 412 may be integral with the pancake probe shield 400 or may be separate. Reference numeral 414 shown in FIG. 30 indicates a knob provided on the upper lid 404.

  The preferred embodiments and modifications of the present invention have been described above. However, the radiation shield according to the present invention has a shielding material such as lead or brass filled in the space surrounded by the outer skin such as stainless steel as described above. In addition to the method of pouring into the outer shell, a method of filling the outer skin with a granular shielding material may be adopted. That is, a configuration in which the granular shielding material is surrounded by the outer skin may be employed. According to this, when the radiation shield according to the present invention is discarded, a hole is made in a part of the outer skin, and the granular shielding material is allowed to flow out of the outer skin hole, so that the outer skin material and the inner skin are removed. The material to be filled in can be easily separated. As a modification, a granular stainless steel material may be filled in a shell such as stainless steel. As a further modification, the outer skin is filled with a shielding metal such as granular lead, brass or stainless steel, and further, a radiation shielding liquid such as water or sodium borate liquid is filled into the outer skin. Good.

  Moreover, regarding the horizontal partitions 20, 302, and 412, the cross-shaped shape is adopted in the embodiment, but the shape of the eye (vacant space) such as the horizontal partition 20 is arbitrary, for example, a shape in which the wire is spiraled May be adopted.

DESCRIPTION OF SYMBOLS 100 Shielding body of 1st Example 2 Shielding body 4 Ceiling lid 6 Bottom lid 6a Bottom lid flange 8 Ceiling lid circular opening 10 Ceiling lid half 12 Hinge 14 Hook 16 Hanging handle 18 Handle 20 Horizontal partition 22 Dish S Sample 300 Small shield 400 Shield for pancake probe

Claims (6)

A cylindrical shielding body with its upper and lower ends open;
A ceiling lid provided at the upper end of the shielding body and having an opening in the central portion;
A bottom lid for closing the lower end of the shielding body;
A radiation shield having a cross-girder horizontal partition provided at a lower end of the shield body.   The radiation shielding body according to claim 1, wherein the shielding body has a height dimension smaller than a length dimension of a cylindrical probe of the radiation measuring instrument.   The radiation shield according to claim 1, wherein the ceiling lid is configured by a pair of ceiling lid halves divided into two.   The radiation shielding body according to any one of claims 1 to 3, further comprising a cylindrical small shielding body that can be accommodated in the shielding body.   The radiation shield according to claim 4, wherein a horizontal partition that communicates vertically is provided at a lower end of the small shield. It further has a cylindrical additional shield that can be placed on the shield body,
A notch through which a pancake probe can pass is provided on the peripheral wall of the additional shield,
The radiation shield according to claim 1, wherein the additional shield is closable by an upper lid.

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