JP2019038337A - Shielding structure for radioactivity-containing cargo transportation vessel - Google Patents

Abstract

To facilitate installation of a facility member to a rear part transverse bulkhead and at the same time suitably reduce a dose rate of a streaming component.SOLUTION: A shielding structure of a radioactivity-containing cargo transportation vessel is provided in a side part area 50 of a hold 3 in a rearmost part of a vessel length direction. The side part area is partitioned into: a side shell; a hold vertical wall 36; a deck 60b provided over the side shell and the hold vertical wall; and a rear part transverse bulkhead 38 installed with a transverse bulkhead shielding body partitioning a zone 40 in hold and rear in a vessel width direction. An opening 39 penetrated by a facility member F is formed on the rear part transverse bulkhead. A shielding body 60S for shielding radioactive rays from a radioactivity-containing cargo is installed in the side part area, between the radioactivity-containing cargo stored in the hold, and the opening. The shielding body includes: a first shielding body 61 extending in the vertical direction; and a second shielding body 62 continuous from the first shielding body 61 and extending in the vessel width direction toward the side shell.SELECTED DRAWING: Figure 4

Description

  TECHNICAL FIELD The present invention relates to a shielding structure for a radioactivity-containing freight carrier carrying a cargo containing radioactivity.

In general, a radioactive cargo ship carrying a large amount of radioactive cargo is used to prevent the crew from being exposed to radiation between the last hold in the direction of the captain and the area behind it. A rear transverse bulkhead with a horizontal transverse barrier shield is made. The rear transverse bulkhead functions as a radiation shield and extends in the ship width direction.
A plurality of through-holes through which equipment members such as pipes penetrate are formed in the side region of the above-mentioned cargo hold in the rear transverse bulkhead. For this reason, a streaming phenomenon in which radiation leaks along the through hole occurs, and a phenomenon occurs in which the dose rate in the through hole and its vicinity increases.

Conventionally, it is known to install a maze-like shielding wall on the engine room side as a shielding structure for coping with this streaming phenomenon.
By the way, the size of the through hole allowed from the viewpoint of preventing the crew from being exposed depends on the attenuation rate of the dose rate by the shielding body and the rate of increase of the dose rate by the streaming component. In addition, the radiation that enters the through hole is predominantly the radiation that reaches directly from the radiation source, and the penetration angle of the radiation that enters the through hole with respect to the ship length direction is small. For this reason, the radiation which passes through a through-hole directly or by several scattering increases, and it exists in the tendency for a dose rate to become large in the exit part of a through-hole.
Accordingly, it is necessary to minimize the area of the through-hole and to install a shielding body on the exit side (rear area side) to reduce the dose rate of the streaming component to the radiation allowable value.

Radiation shielding handbook Fundamentals March 2015 The Japan Atomic Energy Society Reprocessing Facility Radiation Shield Safety Guide Material, JAERI-M 86-060 April 1986 (ed) Sekiguchi Satoshi, Naito Takashi

As described above, in the conventional radioactivity-containing cargo carrier, for example, a plurality of through-holes having different sizes (areas) are formed in the rear transverse bulkhead in order to pass equipment members such as piping. Therefore, in the conventional shielding structure for a radioactive cargo ship, it was necessary to design and construct a shielding body suitable for the size of the opening of each through hole in order to reduce the dose rate of the streaming component. For this reason, there are problems that the design and construction are complicated and costly.
Moreover, also in installation of a shielding body, the construction for penetrating equipment members through the shielding body is necessary, and the construction work of the shielding body has become more complicated.

  The present invention solves the above-mentioned problems, and provides a shielding structure for a radioactive cargo-carrying ship that facilitates installation of equipment members to the rear transverse bulkhead and that can suitably reduce the dose rate of streaming components. Is an issue.

  In order to solve the above-mentioned problems, the shielding structure for a radioactive cargo ship according to the present invention is provided in the side region of the hold at the rearmost part in the direction of the ship and shields the radioactive cargo ship carrying the cargo containing the radioactive material. Structure. The side region is defined by a ship side skin, a vertical hold wall, a deck, and a rear horizontal bulkhead on which a horizontal bulkhead shield is installed. The vertical ship wall partitions the hold in the captain direction. The deck is provided across the ship side outer plate and the hold wall vertical wall. The rear transverse bulkhead partitions the hold and a rear area in the ship width direction. The rear horizontal partition wall is formed with an opening through which the facility member passes. In the side region, a shielding body that shields radiation from cargo containing radioactivity is installed between the cargo containing radioactivity contained in the hold and the opening. The shielding body includes a first shielding body extending in a vertical direction along the vertical wall of the hold and a second shielding continuous with the first shielding body and extending in a ship width direction toward the ship side skin. It is configured with a body.

  In the shielding structure for a radioactive cargo carrier according to the present invention, an equipment member such as a pipe can be penetrated from the side region to the rear region through an opening formed in the rear transverse bulkhead. Therefore, installation of the equipment member with respect to the rear horizontal partition is easy. And the radiation which reaches | attains directly from a radiation source with respect to an opening part can be interrupted | blocked by the shielding body installed in the side part area | region. That is, the radiation that reaches the opening directly from the radiation source, which is dominant as the radiation that enters the opening, can be effectively blocked by the shielding body. Therefore, the dose rate of the streaming component can be suitably reduced.

  Further, in the shielding structure of the radioactive material-containing cargo carrier described above, the shielding body is preferably installed on the deck. By comprising in this way, the heavy shielding body made from concrete, for example, can be stably installed on the deck. Therefore, the fixing strength of the shielding body is improved and the stability against the hull swing is increased.

  Moreover, in the shielding structure of the above-described radioactive material-containing cargo carrier, the first shielding body and the second shielding body are continuous with at least two lumps of shielding bodies in an L shape when viewed from the ship's direction. It is good. In this way, the simple L-shaped configuration when viewed from the ship length direction can effectively shield the radiation that directly reaches the opening from the radiation source.

  Further, in the shielding structure of the radioactive cargo carrier described above, the shielding body is continuous with the front part of the first shielding body and the second shielding body, and is provided with a third shielding provided facing the rear lateral bulkhead. You may have a body. By comprising in this way, the radiation from the front of a 1st shielding body and a said 2nd shielding body can be shielded more effectively. Therefore, the dose rate of the streaming component can be more suitably reduced.

  Further, in the shielding structure of the above-mentioned radioactive material-containing cargo carrier, the shielding body is further provided with a fourth shielding body that is installed in front of the first shielding body and the second shielding body. Good. By comprising in this way, the radiation from the front of a 1st shielding body and a said 2nd shielding body can be shielded more effectively. Therefore, the dose rate of the streaming component can be more suitably reduced. Moreover, the dose rate of a streaming component can be reduced further more suitably by combining with the said 3rd shielding body.

  Moreover, in the shielding structure of the above-described radioactive material-containing cargo carrier, it is preferable that the shielding body is partially or entirely made of concrete blocks. By comprising in this way, it can be set as the shielding structure which combines multiple blocks made from a lightweight concrete compared with the case where concrete is constructed continuously from the 1st shielding body to the 3rd or 4th shielding body. . Therefore, construction becomes easy.

  Moreover, in the shielding structure of the above-described radioactive material-containing freight carrier, it is preferable that adjacent concrete blocks are connected to each other by a connecting member. With such a configuration, construction is facilitated, and the assembling strength of the shielding body is improved, and the stability with respect to the hull swinging can be enhanced.

  In the present invention, it is easy to install the equipment member on the rear transverse bulkhead, and a shielding structure for the radioactive material-containing cargo carrier ship that can suitably reduce the dose rate of the streaming component is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cut perspective view of a radioactivity-containing cargo carrier applied to a shielding structure for a radioactivity-containing cargo carrier according to a first embodiment of the present invention. It is a model top view of the hull which shows a hold and a side area. It is a model cross-sectional view of the hull which shows a hold and a side area | region. It is an expansion perspective view which shows the shielding body installed on the 2nd deck. It is an expansion perspective view which shows the shielding body applied to the shielding structure of the radioactivity containing cargo carrier which concerns on 2nd Embodiment of this invention. It is a schematic plan view of the hull which shows the hold and the side area | region which are applied to the shielding structure of the radioactivity containing cargo carrier which concerns on 3rd Embodiment of this invention. It is a figure which shows the shielding body applied to the shielding structure of the radioactive containing cargo carrier which concerns on 4th Embodiment of this invention, (a) is a perspective view, (b) is explanatory drawing which shows an assembly | attachment structure. (A)-(g) is a schematic cross-sectional view which shows a comparative example and an Example. It is a graph which shows the dose rate of streaming.

Embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
(First embodiment)
As shown in FIG. 1, a radioactivity-containing cargo carrier 1 according to the present invention has a bridge 2 having a steering chamber located behind the hull, and accommodates radioactivity-containing cargo (hereinafter simply referred to as “cargo”). The ship 3 is a ship located in front of the bridge 2. The hold 3 is formed on the inner side of the hull, and the first hold 31, the second hold 32, the third hold 33, the fourth hold 34, and the fifth hold 35 5 in order from the bow side along the length direction (front-rear direction). It is divided into two. Each hold 31-35 has substantially the same shape and substantially the same volume. A cargo RW (see FIG. 2) is accommodated in each of the cargo holds 31-35.

  An entrance (not shown) is formed above each of the cargo holds 31 to 35, and the cargo RW is taken in and out through this entrance. For example, steel hatch covers 31a to 35a each having a concrete shielding body installed therein are covered at each doorway. This prevents leakage of radiation through the doorway.

  As shown in FIG. 2, the hold 3 is partitioned by left and right hold vertical walls 36 extending in the captain direction and a hold horizontal wall 37 extending in the ship width direction. As shown in FIGS. 2 and 3, the fifth cargo hold 35 at the rearmost part in the captain direction is partitioned by a rear lateral bulkhead 38 on the rear side of which a thick concrete lateral bulkhead shield is installed. The horizontal bulkhead shielding body is adjacent to a steel horizontal bulkhead (not shown) at the front end of the engine area. The rear transverse bulkhead 38 covers substantially the entire cross section of the hull, as indicated by the hatched lines in FIG. The rear transverse bulkhead 38 divides the three parts of the hold (the fifth hold 35, an exposed area exposed to radiation) and the area 40 behind it (non-exposed areas, such as a living area, an engine area, etc.). As shown in FIG. 2, the horizontal side wall 37 extends outside the vertical side wall 36 (inside the passage A), and a door 37 a is provided in the extended part. The rear area 40 includes an engine area, a residential area, and the like.

  As shown in FIG. 3, side regions 50 are formed on both outer sides in the ship width direction of the hold 3. Each side region 50 is partitioned in the ship width direction by a vertical hold wall 36 and a ship-side outer plate 55, and in the ship length direction by a rear horizontal partition wall 38 and a front horizontal partition wall (not shown). In addition, each side region 50 of the left and right anchors is partitioned in the vertical direction of the hull by a deck 60 provided across the hold vertical wall 36 and the ship side outer plate 55. The deck 60 is composed of an upper deck 60a and a second deck 60b to a fifth deck 60e in order from the upper side (see FIG. 1).

  In the right side region 50, a passage A is formed on the second deck 60b. As shown in FIG. 4, a square opening 39 is formed in the rear horizontal partition wall 38 that partitions the passage A. The opening 39 functions as a through hole through which a facility member F such as a pipe or an electric wire installed in the hull is penetrated. The equipment member F is disposed through the opening 39, for example, from the rear area 40 side to the passage A (side area 50) side.

  Further, a steel door 38 a is installed in the rear horizontal partition wall 38 that partitions the passage A. As shown in FIG. 2, a concrete shielding wall 38b formed continuously in a labyrinth shape on the rear surface of the rear horizontal partition wall 38 is installed on the side of the area 40 which is the rear side of the door 38a. Thereby, the dose rate of the streaming component through the door 38a is suppressed to an allowable value.

  On the second deck 60b of the passage A, a concrete shielding body 60S is installed. The shielding body 60 </ b> S is installed between the cargo RW as a radiation source accommodated in the hold 3 and the opening 39. Specifically, the shielding body 60S is installed so as to directly shield radiation dominant as a streaming component that directly reaches the opening 39 from each cargo RW accommodated in the first hold 31 to the fifth hold 35. .

As shown in FIG. 3, the shielding body 60 </ b> S is continuous with two or more shielding body lumps at least in a substantially L shape when viewed from the ship's direction, and has an opening edge of the opening 39 formed in the rear transverse partition wall 38. It is made into the shape along. The shielding body 60 </ b> S includes a first shielding body 61 and a second shielding body 62 that continues to the lower side (right side) of the first shielding body 61. The rear surfaces of the first shielding body 61 and the second shielding body 62 are both in contact with the front surface of the rear horizontal partition wall 38.
As shown in FIG. 4, the first shielding body 61 is a rectangular parallelepiped extending in the vertical direction of the passage A along the vertical hold wall 36 and having a rectangular front surface and upper surface.
The second shielding body 62 is a rectangular parallelepiped extending in the ship width direction toward the ship side outer plate 55 and having a rectangular front surface and right side surface. In addition, you may form the 1st shielding body 61 and the 2nd shielding body 62 integrally.
The structure of the shielding body 60S is an L-shaped structure in which two lumps of the first shielding body 61 and the second shielding body 62 are combined, but is not limited thereto. For example, when the amount of radiation intrusion from the ceiling direction is large, it does not preclude providing a shielding body on the ceiling side to form a U-shaped structure when viewed from the ship's direction. Further, the size of the opening 39 may be extended to the vertical hold wall 36.

The first shielding body 61 is directly installed on the second deck 60b. The upper end portion of the first shielding body 61 is disposed close to or in contact with the lower surface of the upper upper deck 60a, and substantially closes the upper and lower spaces of the passage A.
Note that the first shielding body 61 has a gap between the first upper shield 60a and the upper upper deck 60a when the radiation directly reaching the opening 39 can be blocked by the positional relationship between each cargo RW and the opening 39. May be configured.

The second shielding body 62 is directly installed on the second deck 60b in the same manner as the first shielding body 61. That is, since both the first shielding body 61 and the second shielding body 62 are directly placed on the upper surface of the second deck 60b, the stability of the shielding body 60S is improved. The second shielding body 62 is connected to the first shielding body 61 by a fixing member such as a bolt (not shown) with the left end surface thereof in contact with the lower right surface of the first shielding body 61.
The right end portion of the second shielding body 62 is positioned so as to contact the ship side outer plate 55 or to face the ship side outer plate 55 with a gap.

  In the shielding structure of the radioactivity-containing freight carrier 1 of the present embodiment described above, the equipment member F such as piping extending through the side region 50 and the rear region 40 through the opening 39 formed in the rear transverse bulkhead 38 is provided. Can be installed. Therefore, the installation of the equipment member F such as piping for the rear horizontal partition wall 38 is easy. And the radiation which reaches | attains directly from the cargo RW with respect to the opening part 39 can be interrupted | blocked by the concrete shielding body 60S installed in the side part area | region 50. FIG. That is, the radiation directly reaching the opening 39 from the cargo RW, which is dominant as the radiation entering the opening 39, can be effectively blocked by the concrete shielding body 60S. Therefore, the dose rate of the streaming component can be suitably reduced.

  The shielding body 60S is installed on the second deck 60b. Thereby, the heavy concrete shielding body 60S can be stably installed on the second deck 60b. Therefore, the fixing strength of the shielding body 60S is improved, and the stability with respect to the hull swing is increased.

  The first shielding body 61 and the second shielding body 62 are substantially L-shaped when viewed from the ship length direction. In this way, by adopting a simple L-shaped configuration when viewed from the ship's direction, the radiation directly reaching the opening 39 from the cargo RW can be effectively blocked.

  The length in the ship length direction, the height in the up-down direction, and the thickness in the ship width direction of the first shielding body 61 can be appropriately set in consideration of the positional relationship between each cargo RW and the opening 39 and the like. . Similarly, the length in the ship length direction, the thickness in the vertical direction, and the length in the line width direction of the second shielding body 62 can be appropriately set in consideration of the positional relationship between each cargo RW and the opening 39. it can.

(Second Embodiment)
Next, the shielding structure of the radioactive containing cargo carrier of 2nd Embodiment of this invention is demonstrated. This embodiment is different from the first embodiment in that the shielding body 60 </ b> S includes a third shielding body 63.

  As shown in FIG. 5, the third shielding body 63 is a shielding body provided continuously to the front portion 61 a of the first shielding body 61 and the front portion 62 a of the second shielding body 62. The third shielding body 63 is a rectangular parallelepiped whose upper surface and right side surface are rectangular. The third shielding body 63 is disposed so as to face the rear horizontal partition wall 38. The third shielding body 63 extends in the vertical direction along both front portions 61a and 62a so as to cover the entire front portion 61a of the first shielding body 61 and a part of the front portion 62a of the second shielding body 62. doing.

  The right side portion 63 a of the third shielding body 63 is separated from the ship side outer plate 55 (see FIG. 3), and forms an arrangement space for the equipment member F between the inner surface of the ship side outer plate 55.

  In the shielding structure of the radioactive material-containing cargo carrier 1 of the present embodiment, the radiation from the front of the first shielding body 61 and the second shielding body 62 can be more effectively shielded by providing the third shielding body 63. . Therefore, the dose rate of the streaming component can be more suitably reduced.

(Third embodiment)
Next, with reference to FIG. 6, the shielding structure of the radioactive content cargo ship of 3rd Embodiment of this invention is demonstrated. The present embodiment is different from the first and second embodiments in that the shielding body 60S includes a fourth shielding body 64.

The fourth shielding body 64 is a shielding body that is disposed in front of the first shielding body 61 and the second shielding body 62. The fourth shielding body 64 is composed of a total of three shielding bodies 64a to 64c that are arranged at intervals in the front-rear direction of the passage A. Each of the shielding bodies 64a to 64c is a rectangular parallelepiped whose upper surface is rectangular.
In the present embodiment, the respective shielding bodies 64 a to 64 c are arranged substantially in parallel with the first shielding body 61.

The lengths of the shielding bodies 64 a and 64 b on the side close to the first shielding body 61 are set to be slightly shorter than the length of the first shielding body 61 in the front-rear direction. Further, the length in the front-rear direction of the shielding body 64c arranged in front of these is set to be shorter than the length in the front-rear direction of the shielding bodies 64a, 64b.
The length in the ship length direction, the height in the vertical direction, and the thickness in the ship width direction of each shielding body 64a to 64c can be appropriately set in consideration of the positional relationship between the opening 39 and the cargo RW. .

  In the shielding structure of the radioactive material-containing cargo carrier 1 according to the present embodiment, the radiation from the front of the first shielding body 61 and the second shielding body 62 can be more effectively shielded by the fourth shielding body 64. Therefore, the dose rate of the streaming component can be more suitably reduced. In addition, by combining the third shielding body 63 and the fourth shielding body 64 described above, the dose rate of the streaming component can be further suitably reduced.

(Fourth embodiment)
Next, with reference to FIG. 7, the shielding structure of the radioactive content containing cargo carrier of 4th Embodiment of this invention is demonstrated. The present embodiment is different from the first to third embodiments in that the first shielding body 61 and the second shielding body 62 are configured by combining a plurality of concrete blocks 65.

A concrete block (hereinafter simply referred to as “block”) 65 is a plate-shaped rectangular parallelepiped as shown in FIG. The first shielding body 61 is configured by arranging three blocks 65 in the ship length direction (front-rear direction) and arranging four blocks 65 in the ship width direction (left-right direction).
On the other hand, the second shielding body 62 has the same configuration, and includes three blocks 65 arranged in the ship length direction and four blocks 65 arranged in the vertical direction.
In the present embodiment, the size of the block 65 to be used is different between the first shielding body 61 and the second shielding body 62, and the size of the second shielding body 62 is smaller than that of the first shielding body 61. It is set. Of course, the first shielding body 61 and the second shielding body 62 may be configured by a block 65 having the same size in accordance with the setting of the size of the passage A, etc. Compared to that of the first shielding body 61. The second shield 62 may be set larger.
The joints of the blocks 65 are adjacent to each other without being alternately arranged in the ship width direction or the vertical direction. Thereby, the structure of the 1st shielding body 61 and the 2nd shielding body 62 is a simple thing. In addition, even if it is the structure where the joint of the block 65 is adjacent, a radiation can be interrupted | blocked suitably.

As shown in FIG. 7B, the plurality of blocks 65 can be fixed integrally using, for example, a frame-like member (connection member) 70. The frame-like member 70 is made of steel and includes a plurality of concave accommodating portions 71 that accommodate the ends of the blocks 65. Each block 65 is formed with a bolt insertion hole (not shown) that is tightened through the frame-like member 70. The frame members 70 are fixed to each other by, for example, screwing bolts inserted through the insertion holes into nuts (not shown).
In addition, you may comprise so that the adjacent blocks 65 may be directly connected using other connection members, such as a volt | bolt and a nut which are not shown in figure, without using the frame-shaped member 70. FIG.

  It is desirable that the block 65 has a weight suitable for manufacture and combination, for example, a weight of about 50 kg per sheet.

  In the shielding structure of the radioactivity-containing cargo carrier 1 of the present embodiment, a shielding structure formed by combining a plurality of lightweight blocks 65 can be provided, and the construction to the passage A is facilitated.

  Further, since the adjacent blocks 65 are connected to each other by a connecting member such as a frame-shaped member 70 and a bolt, the construction is easy and the assembling strength of the shielding body is improved and the hull swings. High stability against

(Comparative Example 1-2, Example 1-5)
Hereinafter, the present invention will be described more specifically with reference to examples. The following examples do not limit the present invention.
Below, the result evaluated about the test regarding the shielding performance of the radiation (gamma ray) by the shielding body 60S is demonstrated.
(Testing method for shielding performance)
A test method relating to shielding performance will be described with reference to FIG. Note that the evaluation position of the dose rate is a position where the dose rate of the streaming component is predicted to be large, for example, the corner between the rear surface of the rear transverse bulkhead 38 (the surface on the rear area 40 side) and the inner surface of the ship side skin 55. It was set as the vicinity position (position shown by the code | symbol P in FIG. 4).
Further, the shielding analysis for gamma rays emitted from the cargo RW was performed using the safety analysis code QAD-CGGP2R.
In FIG. 9, the hatched portion indicates the dose rate from the fifth hold 35 closest to the rear transverse bulkhead 38, and the plurality of white portions below it are The dose rate from each hold other than is shown.

  In Comparative Example 1, as shown in FIG. 8A, the rear side of the passage A is closed with a thick concrete rear lateral partition wall 38, that is, no opening 39 such as a pipe is formed. It is a configuration that is not done. In Comparative Example 1, since the opening 39 is not provided, the dose rate at the evaluation position is naturally kept low as shown in FIG. 9, and high shielding properties are secured.

  In Comparative Example 2, as shown in FIG. 8B, the opening 39 is formed in the rear lateral partition wall 38 on the rear side of the passage A, but the shielding body 60S is not installed. In Comparative Example 2, as shown in FIG. 9, since the opening 39 is only formed, the dose rate at the evaluation position becomes high, and the shielding property is not ensured.

  In Example 1, as shown in FIG. 8C, a first shielding body 61 and a second shielding body 62 having the structure shown in the first embodiment are installed. The thicknesses of the first shielding body 61 and the second shielding body 62 are both 20 cm. The lengths of the first shielding body 61 and the second shielding body 62 in the ship length direction (front-rear direction) are both 200 cm. In Example 1, as shown in FIG. 9, the dose rate at the evaluation position was suppressed lower than that in Comparative Example 2, and it was confirmed that high shielding properties were ensured.

  Example 2 is a modified example of Example 1 as shown in FIG. 8 (d), and the thicknesses of the first shielding body 61 and the second shielding body 62 are increased as compared with Example 1, respectively. In addition, the length in the ship length direction (front-rear direction) is set to 500 cm. In Example 2, as shown in FIG. 9, the dose rate at the evaluation position was suppressed to be lower than that in Example 1, and it was confirmed that higher shielding properties were ensured.

  Example 3 has the structure shown in the third embodiment, as shown in FIG. 8 (e), and a third shielding body 63 is installed in front of the first shielding body 61 and the second shielding body 62. It is a thing. The first shielding body 61 and the second shielding body 62 are the same as in the first embodiment. The thickness of the third shield 63 is 20 cm, and the width in the ship width direction is 100 cm. In Example 3, as shown in FIG. 9, the dose rate at the evaluation position was suppressed to be lower than that in Example 1, and it was confirmed that high shielding properties were ensured.

  Example 4 is a first modification of Example 3 as shown in FIG. 8 (f), in which the thicknesses of the first shielding body 61 and the second shielding body 62 are increased to 30 cm, and in addition, The thickness of the third shielding body 63 is also increased to 30 cm. In Example 4, as shown in FIG. 9, the dose rate at the evaluation position was suppressed to be lower than that in Example 3, and it was confirmed that a higher shielding property was secured.

Example 5 is a second modification example of Example 3 as shown in FIG. 8 (g), in which the thicknesses of the first shielding body 61 and the second shielding body 62 are further increased to 40 cm and added. Thus, the thickness of the third shielding body 63 is further increased to 40 cm. In Example 5, as shown in FIG. 9, the dose rate at the evaluation position was kept lower than those in Examples 3 and 4, and it was confirmed that higher shielding properties were ensured.
In addition, about Example 1-5, although not shown in figure, the shielding analysis of the neutron beam was performed using the Monte Carlo code | cord MCNP. As a result, it was confirmed that sufficient shielding properties were secured to prevent the crew from being exposed to neutrons, which have a higher wraparound effect than gamma rays.

The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention.
In the said embodiment, although the 2nd shielding body 62 was set as the structure which continues to the lower part of the 1st shielding body 61, it is not restricted to this, It is good also as a structure which continues to the upper part and middle part of the 1st shielding body 61. . That is, the second shielding body 62 can be configured to be continuous with an appropriate position of the first shielding body 61 in consideration of the positional relationship between the opening 39 and the cargo RW.

  Moreover, although the 1st shielding body 61 showed what was directly installed on the 2nd deck 60b, it is not restricted to this, It is good also as a structure mounted on the 2nd shielding body 62. FIG.

Moreover, in 1st Embodiment, although the shielding body 60S comprised the 1st shielding body 61 and the 2nd shielding body 62 which were made into a different body, it is not restricted to this, These were comprised integrally. It may be.
Also in the shielding body 60S shown in the second embodiment, the third shielding body 63 may be configured integrally with the first shielding body 61 and the second shielding body 62.

  Moreover, in the said 3rd Embodiment, although what has arrange | positioned each shielding body 64a-64c substantially parallel to the 1st shielding body 61 was shown, it is not restricted to this, The direction which crosses the 1st shielding body 61 You may arrange in. In addition, the number, shape, and the like can be arbitrarily set.

  Further, in the fourth embodiment, the height, width, and thickness of the block 65 are configured to be uniform. However, the present invention is not limited to this, and the height, width, and thickness are made different by partially different dimensions. Also good.

  Moreover, in the said embodiment, although the material of the horizontal partition shielding body, the block of the shielding body 60S, and the block 65 is concrete, it is not restricted to this. For example, according to the type of radiation emitted from the cargo, the transverse bulkhead shielding body, shielding body 60S is made of a single or combination of metals such as iron and lead, resins such as polyethylene and silicon rubber, crushed sand and crushed stone. You may use as a material of a block and the block 65. FIG.

1 Radioactive Cargo Carrier 3 Funakura 35 5th Funakura (Funakura at the end in the direction of the captain)
36 Longitudinal wall of the cargo hold 37 Lateral transverse wall 38 Rear lateral bulkhead 39 Opening area 40 Rear area 50 Side area 55 Ship side skin 60 Deck 60S Shielding body 61 First shielding body 62 Second shielding body 63 Third shielding body 64 Fourth shielding Body 65 Concrete block 70 Frame member A Passage F Equipment member RW Cargo containing cargo (cargo)

Claims (7)

A shielding structure for a radioactive cargo carrier that is provided in a side area of the hold at the rearmost part in the direction of the captain and carries cargo containing radioactive radiation,
The side area includes a ship side skin, a ship vertical wall that partitions the hold in the direction of the ship, a deck provided across the ship side skin and the ship vertical wall, the ship and the rear area. And a rear horizontal bulkhead where a horizontal bulkhead shielding body is installed to divide the
The rear lateral partition wall is formed with an opening through which the facility member passes,
In the side region, a shielding body that shields radiation from cargo containing radioactivity is installed between the cargo containing radioactivity contained in the hold and the opening,
The shield is
A first shielding body extending in the vertical direction along the vertical wall of the hull, and a second shielding body continuous with the first shielding body and extending in the ship width direction toward the ship side skin. A shielding structure for a radioactive cargo carrier characterized by being constructed.   The said shielding body is installed on the said deck, The shielding structure of the radioactive containing cargo carrier of Claim 1 characterized by the above-mentioned.   The said 1st shielding body and said 2nd shielding body are continuous by the lump of two or more shielding bodies at least L shape seeing from the ship length direction, The Claim 1 or Claim 2 characterized by the above-mentioned. Shielding structure for cargo carriers with radioactive materials.   The said shielding body is provided with the 3rd shielding body provided in the front part of said 1st shielding body and said 2nd shielding body, and facing the said rear horizontal partition. The shielding structure of the radioactive material-containing cargo carrier of any one of Claim 3.   The said shielding body is provided with the 4th shielding body spaced apart and installed in front of said 1st shielding body and said 2nd shielding body, The any one of Claim 1 to 4 characterized by the above-mentioned. The shielding structure of the cargo carrier with radioactive content described in 1.   6. The shielding structure for a radioactive cargo-containing cargo carrier according to claim 1, wherein a part or all of the shielding body is made of a concrete block. 7.   The shielding structure for a radioactive material-containing cargo carrier according to claim 6, wherein the concrete blocks adjacent to each other are connected to each other by a connecting member.

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