JP2014052266A - Neutron beam shield structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a neutron beam shield structure which is attached to an aperture formed on a wall of a room in which a beam dump device is installed, is easily attached or disassembled, and is capable of effectively reducing leakage of radiation to the outside of the room.SOLUTION: A neutron beam shiel structure 10 includes: an indoor side concrete part 11 which is formed of low activation concrete and attached to the indoor side; an outdoor side concrete part 12 which is configured by laminating tabular concrete members 121 to 128 formed of normal concrete in a direction from the indoor side to the outdoor side an attached to the outdoor side; and a boron-containing sheet 13 formed so as to be held between the indoor side concrete part 11 and the outdoor side concrete part 12. The neutron beam shield structure 10 has such a shape that a width-direction dimension and a height-direction dimension are gradually increased in a direction from the indoor side to the outdoor side. The neutron beam shield structure 10 is attached to an aperture 4 formed on the rear side of a beam dump device of an accelerator room shield wall 1.

Description

  The present invention relates to a neutron beam shielding structure attached to an opening provided in a wall of a room where a charged particle collision device such as a beam dump device is installed.

Conventionally, in a facility equipped with an accelerator that accelerates charged particles such as protons and electrons, a beam as a charged particle collision device is used to make unnecessary charged particles collide with a target such as carbon (dump target) and disappear. A dump device is provided (see, for example, Patent Document 1).
The beam dump apparatus is usually installed in a room adjacent to a room where an accelerator, which is a radiation source, is installed, or in a room partitioned by a concrete wall. Charged particles that are no longer needed after being accelerated by the accelerator are introduced into the room where the beam dump device is installed by the particle introduction tube, and are irradiated to the dump target from the end of the particle introduction tube.
The accelerator and the beam dump device are built into a room from an opening provided in the shielding wall after a room surrounded by a concrete shielding wall and is installed at a predetermined position.
Similarly, when installing an accelerator and a charged particle collision device (beam generator) that collides charged particles accelerated by the accelerator to generate neutron rays or X-rays, it is surrounded by a concrete shielding wall. After constructing the room, the accelerator and the beam generator are carried into the room through the opening provided in the shielding wall.

JP 2007-242468 A

By the way, after installing charged particle collision devices such as an accelerator and a beam dump device, the opening is filled with concrete and the opening is closed. After the accelerator experiment is finished, the concrete is dismantled and the charged particle collision device Need to be removed from the opening.
However, when the opening is made into a frame shape and concrete is filled in the frame and the opening is closed, there is a problem that dust is generated at the time of dismantling. In addition, the room where the charged particle colliding device is installed is a radiation control area, so there is a problem that the efficiency of the dismantling work is low because it is necessary to divide the concrete into several times and to perform each in a short time. .

Therefore, it is conceivable to prepare a concrete shielding door that is stored in the opening in advance, and to electrically open and close the shielding door by placing it on a rail with a jack or the like. Since it is necessary to secure the laying location, there arises a problem that a part of the building has to be significantly changed.
Further, when the opening has a frame shape, radiation may leak out of the room from the gap between the filled concrete and the shielding wall.

  The present invention has been made in view of conventional problems, and is provided on a wall of a room where a charged particle collision device such as a beam dump device is installed and attached to an opening. An object of the present invention is to provide a neutron beam shielding structure capable of effectively reducing leakage to the outdoors.

The present invention relates to an opening provided in a shielding wall opposite to the radiation source side of the charged particle collision apparatus in a room where a charged particle collision apparatus including a target that collides charged particles emitted from a radiation source is installed. A neutron beam shielding structure attached to a part, which is made of low-activation concrete and is attached to the indoor side of the opening, and an outdoor concrete part attached to the outdoor side of the opening; A boron-containing sheet provided so as to be sandwiched between the indoor-side concrete part and the outdoor-side concrete part, and the outdoor-side concrete part moves the plate-shaped concrete member from the indoor side to the outdoor side. The neutron beam shielding structure is formed by being laminated in the direction in which the dimension in the width direction and the dimension in the height direction both go from the indoor side to the outdoor side. Characterized in that it has increased in a stepwise manner me.
A charged particle collision device is a beam dump device that makes charged particles that are no longer needed collide with a target (dump target) such as carbon and attenuates it, or a target (beam target) that collides protons or electrons accelerated by an accelerator. This refers to a beam generator that generates neutrons and X-rays.
By adopting such a configuration, when attaching the neutron beam shielding structure, the plate-like concrete members are sequentially laminated from the indoor side to the outdoor side, and at the time of dismantling, the plate-like concrete members are sequentially placed from the outdoor side to the indoor side. Since it should just be removed, the attachment work and the dismantling work of the neutron beam shielding structure can be easily performed.
In addition, radiation that leaks from the space between the neutron beam shielding structure and the shielding wall to the outside can be effectively reduced, and the concrete in the opening for carrying in and out of the beam dump device is suppressed from being activated. Therefore, it is possible to avoid an adverse effect on the removal of the opening due to the carrying out of the beam dump device.

Moreover, since the said concrete member was comprised from the some precast concrete board arranged in the width direction, attachment and dismantling of a neutron beam shielding structure can be performed still more easily.
Further, since the boron-containing sheet is provided on the plate surface of the precast concrete plate by allowing the boron-containing resin to flow and harden on the plate surface of the precast concrete plate after production, it is provided on one plate surface of the precast concrete plate. A precast concrete board provided with a boron-containing layer can be easily produced.

  The summary of the invention does not list all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

It is a figure which shows the structure of the neutron beam shielding structure which concerns on this Embodiment. It is a figure which shows the outline | summary of the accelerator chamber shielding wall to which the neutron beam shielding structure was attached. It is a figure which shows the precast concrete board of a neutron beam shielding structure. It is a figure which shows the detailed structure of a neutron beam shielding structure. It is a figure which shows the attachment method of a neutron beam shielding structure. It is a figure which shows the dismantling method of a neutron beam shielding structure. It is a figure which shows the other structure of the neutron beam shielding structure by this invention.

  Hereinafter, the present invention will be described in detail through embodiments, but the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

1A is a plan view showing the configuration of the neutron beam shielding structure 10, FIG. 1B is a view taken along the line AA in FIG. 1A, and FIG. is there. As shown in FIG. 2, the neutron beam shielding structure 10 is an accelerator constructed so as to surround an accelerator device 2 installed in a test building for testing an accelerator and a beam dump device 3 as a charged particle collision device. It is attached to the opening 4 provided in the room shielding wall 1.
In addition, the code | symbol 5 of the figure is a partition wall provided between the accelerator apparatus 2 and the beam dump apparatus 3. FIG.
The accelerator chamber shielding wall 1 and the partition wall 5 are formed by a reinforced concrete structure including ordinary concrete and a reinforcing bar (not shown). Ordinary concrete is formed by kneading aggregate obtained from river sand, sea sand, mountain sand, crushed stone, crushed sand, cement, and water.
The accelerator chamber shielding wall 1 has a thickness of 1.52 m, which is thicker than the necessary shielding performance of ordinary concrete, 1.52 m, and the partition wall 5 has a thickness of about 50 cm.
The opening 4 is provided at a position facing the entrance / exit 8 provided in the outer wall 7 of the test building.

The accelerator device 2 includes a generation unit 2a that generates charged particles, an accelerator body 2b that accelerates charged particles, and a measurement unit 2c that measures characteristics of the accelerated charged particles.
The beam dump device 3 includes a dump target 3a that causes charged particles induced by the particle introduction tube 6 from the measurement unit 2c to collide and disappear, and a radiation shield 3b that is provided so as to surround the dump target 3a. A mechanism (not shown) for cooling the dump target 3a is provided in the radiation shield 3b.
After the construction of the accelerator chamber shielding wall 1 and the partition wall 5, the beam dump device 3 is carried into the room surrounded by the accelerator chamber shielding wall 1 and the partition wall 5 from the opening 4. After carrying in the apparatus, the neutron beam shielding structure 10 is attached to the opening 4 to close the opening 4.
The opening 4 is such that both the dimension in the width direction that is the extension direction of the accelerator chamber shielding wall 1 and the dimension in the height direction that is the vertical direction increase stepwise from the indoor side toward the outdoor side. It is formed.

The neutron beam shielding structure 10 includes an indoor concrete portion 11 attached to the indoor side of the opening 4, an outdoor concrete portion 12 attached to the outdoor side of the opening 4, the indoor concrete portion 11, and the outdoor concrete portion. And a boron-containing sheet 13 provided so as to be sandwiched therebetween.
The indoor concrete portion 11 is formed by arranging a plurality of precast concrete plates 11k made of low activation concrete as shown in FIG. 3A in the width direction, and is generated as the charged particles colliding with the dump target 3a disappear. The neutron beam functions as a deceleration layer for reducing the speed of the neutron beam to be easily absorbed by the boron-containing sheet 13. In this example, the thickness dimension of the precast concrete board 11k was 165 mm. Low-activation concrete is concrete formed using high-purity aggregate that is difficult to be activated as aggregate (for example, limestone with low impurities such as Na, Co, Eu, etc.). Activation can be suppressed.
As shown in FIG. 3C, the outdoor concrete portion 12 includes plate-like concrete members 121 to 128 formed by arranging a plurality of precast concrete plates 12 k made of ordinary concrete in the width direction from the indoor side to the outdoor side. Is formed by laminating in the direction toward the surface, and functions as a structure that shields radiation other than neutrons, for example, γ rays, and bears the strength of the neutron beam shielding structure 10. In this example, the thickness dimension of the precast concrete plate 12k is 170 mm, and the plate-like concrete member is eight layers. Therefore, the thickness of the outdoor concrete portion 12 is 1360 mm.
In this example, the precast concrete plates 11k and 12k are both reinforced concrete structures.

The boron-containing sheet 13 is a synthetic resin containing boron and has water shielding properties and flexibility. The boron-containing sheet 13 can be formed, for example, by adding boron carbide (B ₄ C) powder to a resin such as methyl methacrylate resin (MMA resin).
In this example, the boron-containing sheet 13 is provided in advance on the plate surface of the precast concrete plate 11k. Specifically, after the precast concrete plate 11k is manufactured from low activation concrete, a boron-containing resin is poured onto the plate surface of the precast concrete plate 11k and cured to obtain a plate as shown in FIG. A composite precast concrete board 14 having a boron-containing sheet 13 provided on the surface is obtained. Therefore, if the side of the composite precast concrete plate 14 on which the boron-containing sheet 13 is provided is the outdoor side, and the precast concrete plate 12k of the outdoor concrete portion 12 is disposed outside the composite precast concrete plate 14, the boron-containing sheet 13 Can be disposed so as to be sandwiched between the indoor concrete portion 11 and the outdoor concrete portion 12. In this example, the thickness dimension of the boron-containing sheet 13 is 5 mm.

In this example, by stacking six composite precast concrete plates 14 having a width dimension of 600 mm and a height dimension of 3000 mm in the width direction, the width dimension is 3600 mm and the height dimension is 3000 mm. The indoor side concrete part 11 was formed. The composite precast concrete board 14 is attached to the opening 4 so that the indoor-side surface of the indoor-side concrete portion 11 is a surface of low-activation concrete, and the outdoor-side surface is a surface of the boron-containing sheet 13.
As shown in FIG. 4, the composite precast concrete plate 14 is fixed by bolts 21 from the indoor side of the accelerator chamber shielding wall 1 to the upper side and the lower side of the opening 4 of the accelerator chamber shielding wall 1.
Specifically, nuts 22 are embedded in the upper and lower sides of the opening 4 of the accelerator chamber shielding wall 1 and the upper and lower sides of the composite precast concrete plate 14, and are provided on the flat mounting plate 23. The composite precast concrete plate 14 is fixed to the accelerator chamber shielding wall 1 by screwing the bolt 21 into the nut 22 from the bolt hole.

The dimension in the width direction and the dimension in the height direction of the concrete members 121 and 122 located on the innermost room side of the outdoor concrete part 12 are the same as the dimension in the width direction and the height direction of the indoor concrete part 11. .
The concrete member 121 located on the innermost side is laminated with five precast concrete plates 12k having the same width and height dimensions as the composite precast concrete plate 14 in the width direction, and the width direction is precast. The precast concrete plate 12k, which is half of the concrete plate 12k, is disposed at both ends in the width direction. The concrete member 122 adjacent to the concrete member 121 is formed by laminating six precast concrete plates 12k having the same width and height dimensions as the composite precast concrete plate 14 in the width direction.
Thus, if the precast concrete plates 11k and 12k are arranged so as to shift the positions of the joints of the precast concrete plates 11k and 12k, the strength of the neutron beam shielding structure 10 can be increased.
The composite precast concrete plate 14 and the precast concrete plate 12k of the concrete member 121 are connected from the outside of the accelerator chamber shielding wall 1. Specifically, a nut 22 is embedded in the composite precast concrete plate 14 in advance, a bolt hole 24 communicating with the nut 22 is provided in the precast concrete plate 12k, and the bolt 21 is connected to the nut 22 through the bolt hole 24 from the outdoor side. The precast concrete plate 12k of the concrete member 121 is fixed to the composite precast concrete plate 14 by screwing into the composite precast concrete plate 14.
The connection between the precast concrete plate 12k of the concrete member 121 and the precast concrete plate 12k of the concrete member 122 is the same.

Moreover, the dimension of the width direction of the concrete members 123-125 arrange | positioned on the thickness direction outer side of the concrete member 122 and the dimension of a height direction are the dimension of the width direction of the indoor side concrete part 11 and the concrete members 121,122. The dimension in the width direction and the dimension in the height direction of the concrete members 126 to 128 that are larger than the dimension in the height direction and are arranged on the outer side in the thickness direction of the concrete member 125 are the dimensions in the width direction of the concrete members 123 to 125. And larger than the height dimension.
In addition, the precast concrete board which comprises the concrete members 123-128 is also larger in the width direction dimension than the precast concrete board which has the dimension of the width direction same as the precast concrete board 12k, and the dimension of a height direction, and the precast concrete board 12k. Alternatively, if small precast concrete plates are laminated in the width direction, the positions of the seams of the precast concrete plates adjacent in the thickness direction can be shifted.

The connection between the precast concrete plate 12k of the adjacent concrete member 12n (n = 2 to 7) and the precast concrete plate 12k of the concrete member 12 (n + 1) is performed by the above-described composite precast concrete plate 14 and the precast concrete plate 12k of the concrete member 121. This is the same as the connection.
As shown in FIG. 4, the precast concrete plate 12 k of the outermost concrete member 128 is fixed with bolts 21 from the outside of the accelerator chamber shielding wall 1 to the upper side of the opening 4 of the accelerator chamber shielding wall 1 and the floor surface 9. Is done.
Specifically, nuts 22 are embedded in the upper side and floor surface of the opening 4 of the accelerator chamber shielding wall 1 and the upper side and floor surface 9 of the precast concrete plate 12k, and the flat mounting plate 25 and the cross section are cross-sectioned. The bolt 21 is screwed into the nut 22 from the bolt hole 24 provided in the L-shaped mounting plate 26, so that the precast concrete plate 12 k of the concrete member 128 is attached to the accelerator chamber shielding wall 1 and the floor surface 9. Fix it.

  In this way, the dimensions in the width direction and the dimensions in the height direction of the concrete members 123 to 125 arranged on the outdoor side of the indoor side concrete part 11 and the concrete members 121 and 122 are determined as the indoor side concrete part 11 and the concrete member 121. , 122 larger than the dimension in the width direction and the dimension in the height direction, and the dimension in the width direction and the dimension in the height direction of the concrete members 126 to 128 arranged on the outdoor side of the concrete members 123 to 125 are made to be concrete members. If the dimension in the width direction and the dimension in the height direction of 123 to 125 are made larger, it is possible to obtain the neutron beam shielding structure 10 that increases stepwise from the indoor side to the outdoor side.

Next, the attachment method and removal method of the neutron beam shielding structure 10 of the present invention will be described.
First, as shown in FIG. 5 (a), the composite precast concrete plates 14 stacked in a material storage place outside the figure are laid flat at a built-in position by a small crane 31.
Next, as shown in FIG. 5 (b), the upper side of the opening 4 of the accelerator chamber shielding wall 1 is connected to the wire 32 fixed to the outdoor end (hereinafter referred to as the head) of the composite precast concrete plate 14. By pulling out the outside of the wire 32 through the ring of the eyebolt 33 attached to the wall of the wall and connecting the lead-out end of the wire 32 to a small winch 34 such as a chill hole, and the worker M winds the wire 32 with the small winch 34 The head of the composite precast concrete board 14 is raised manually. At this time, if the wire 36 attached to the outdoor side end side of the composite precast concrete plate 14 is simultaneously pulled up by the hoist crane 35 previously installed on the outdoor upper part of the opening 4 of the accelerator chamber shielding wall 1, the composite precast The concrete board 14 can be raised easily.

Next, as shown in FIG.5 (c), the wires 32 and 36 and the eyebolt 33 are removed, and the raised composite precast concrete board 14 is fixed to the opening part 4 of the accelerator chamber shielding wall 1 from the indoor side. In the same manner, the remaining five composite precast concrete plates 14 are sequentially fixed to the opening 4 of the accelerator chamber shielding wall 1 to form the indoor concrete portion 11.
The precast concrete plate 12k of the concrete members 121 to 128 of the outdoor concrete portion 12 is attached in the same manner as the composite precast concrete plate 14 except that the fixed side is the composite precast concrete plate 14 or the precast concrete plate 12k previously attached. Thus, it can be fixed to the opening 4 of the accelerator chamber shielding wall 1.
The precast concrete plate 12k of the outermost concrete member 128 is raised by the same method as the composite precast concrete plate 14, and then, as described above, the accelerator chamber shielding wall 1 from the outside of the accelerator chamber shielding wall 1 is used. It is fixed to the upper side of the opening 4 and the floor surface.
In addition, a lead feeler plate is inserted as an expansion joint in three spaces for each layer, and further, between the precast concrete plate 12k of the outermost concrete member 128 and the accelerator chamber shielding wall 1 and the floor surface, and the precast concrete plate Sealing the 12k seam can improve water shielding and airtightness.

Removal is performed in the reverse order of the installation procedure.
First, after removing the bolts fixing the precast concrete plate 12k to the accelerator chamber shielding wall 1 and the floor surface, as shown in FIG. 6A, the uppermost side of the precast concrete plate 12k of the outermost concrete member 128 is provided. One end side of the wires 37 and 38 is respectively attached to the lower end side and the other end side of the wires 37 and 38 is attached to the hoist crane 35 and the small crane 31.
Then, as shown in FIG. 6 (b), the lower end side of the precast concrete plate 12k is shifted to the outdoor side while being lifted by the small crane 31, and the direction of the precast concrete plate 12k is turned sideways.
Next, as shown in FIG.6 (c), the precast concrete board 12k is lowered | hung to a floor using the hoist crane 35 and the small crane 31, Then, the wires 37 and 38 are removed. And the precast concrete board 12k is carried out to the exterior of a test building with the small crane 31. FIG.
If the remaining precast concrete plate 12k of the concrete member 128, the precast concrete plate 12k of the concrete members 121 to 127, and the composite precast concrete plate 14 are removed by the same method, the neutron beam shielding structure is obtained without crushing the concrete. 10 can be removed.

In the above embodiment, the width direction dimension and the height direction dimension of the neutron beam shielding structure 10 are set in three stages. However, the present invention is not limited to this, and the length of the opening 4 (from the indoor side) What is necessary is just to determine suitably by the distance to the outdoor side.
Further, the number of the composite precast concrete plate 14 and the precast concrete plate 12k in the width direction is also appropriately determined depending on the length of the opening 4.
Moreover, in the said embodiment, although the indoor concrete part 11 was made into 1 layer and the outdoor concrete part 12 was made into 8 layers, the number of layers of the indoor concrete part 11 and the outdoor concrete part 12 is also the length of the opening part 4. May be determined as appropriate.
The thickness of the boron-containing sheet 13 is preferably set according to the thickness of the indoor concrete portion 11 made of low activation concrete, the expected amount of neutron beams generated by the beam dump device 3, and the like.

Moreover, in the said embodiment, while the indoor side concrete part 11 was comprised with the some precast concrete board 14, and the concrete members 121-128 of the outdoor side concrete part 12 were comprised with the some precast concrete board 12k, As shown in FIG. 7, you may comprise the indoor side concrete part 11 and the concrete members 121-128 with one concrete board.
In this case, since the work of laminating the precast concrete plates 11k and 12k is eliminated, the work process itself is reduced. However, as in the present embodiment, it is preferable to use the precast concrete plates 11k and 12k having a small weight and volume. It is preferable because the concrete plate can be easily attached and removed.

Moreover, in the said embodiment, although the composite precast concrete board 14 which provided the boron containing sheet | seat 13 previously on the board surface of the precast concrete board 11k was used, the boron containing sheet | seat 13 was formed separately and the board of the precast concrete board 11k was used. You may form the composite precast concrete board 14 by adhere | attaching on the surface.
In addition, it is possible to affix the boron-containing sheet 13 on the surface of the precast concrete plate 11k at the installation site, but it is more efficient to manufacture the composite precast concrete plate 14 in advance as in this example. It is advantageous.

  Moreover, although the said embodiment demonstrated the beam dump apparatus 3 provided with the dump target 3a which collides and extinguishes the unnecessary charged particle induced | guided | derived from the measurement part 2c as a charged particle collision apparatus, this invention The neutron beam shielding structure is provided on the wall of a room in which a beam generator equipped with a beam target for generating a neutron beam, an X-ray beam, etc. by colliding with a proton or an electron accelerated by the accelerator body 2b. The same effect can be obtained even if it is attached to the opened portion.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the embodiment. It is apparent from the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  According to the present invention, it is possible to obtain a neutron beam shielding structure attached to the opening of the accelerator chamber shielding wall, which can be easily attached and disassembled and can effectively reduce the leakage of radiation to the outside of the room. The dumping device can be carried in and out safely and quickly.

1 Accelerator chamber shielding wall, 2 Accelerator device, 2a generator, 2b Accelerator body,
2c measuring unit, 3 beam dump device, 3a dump target, 3b cooling unit,
4 opening, 5 partition wall, 6 particle introduction pipe, 7 outer wall, 8 doorway, 9 floor surface,
10 Neutron beam shielding structure, 11 Indoor concrete part,
11k, 12k precast concrete board, 12 outdoor concrete,
121-128 concrete members, 13 boron-containing sheets,
14 Composite precast concrete board.

Claims (3)

It is attached to an opening provided on a wall opposite to the radiation source side of the charged particle collision device in a room where a charged particle collision device having a target for colliding charged particles emitted from a radiation source is installed. A neutron shielding structure,
An indoor concrete portion formed from low activation concrete and attached to the indoor side of the opening; an outdoor concrete portion attached to the outdoor side of the opening; the indoor concrete portion and the outdoor concrete portion; A boron-containing sheet provided so as to be sandwiched between, the outdoor concrete portion is formed by laminating a plate-shaped concrete member in a direction from the indoor side toward the outdoor side,
A neutron beam shielding structure characterized in that both the dimension in the width direction and the dimension in the height direction of the neutron beam shielding structure increase stepwise from the indoor side toward the outdoor side.   2. The neutron beam shielding structure according to claim 1, wherein the plate-like concrete member is composed of a plurality of precast concrete plates arranged in a width direction.   3. The neutron according to claim 2, wherein the boron-containing sheet is provided on the plate surface of the precast concrete plate by the boron-containing resin being poured and cured on the plate surface of the precast concrete plate after manufacture. Line shielding structure.

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