JPH0131160B2 - - Google Patents
Info
- Publication number
- JPH0131160B2 JPH0131160B2 JP14144280A JP14144280A JPH0131160B2 JP H0131160 B2 JPH0131160 B2 JP H0131160B2 JP 14144280 A JP14144280 A JP 14144280A JP 14144280 A JP14144280 A JP 14144280A JP H0131160 B2 JPH0131160 B2 JP H0131160B2
- Authority
- JP
- Japan
- Prior art keywords
- neutron
- air conditioning
- conditioning duct
- neutrons
- synthetic resin
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000004378 air conditioning Methods 0.000 claims description 28
- 230000005855 radiation Effects 0.000 claims description 12
- 229920003002 synthetic resin Polymers 0.000 claims description 9
- 239000000057 synthetic resin Substances 0.000 claims description 9
- 150000001639 boron compounds Chemical class 0.000 claims description 4
- 238000009423 ventilation Methods 0.000 claims description 4
- 229910052793 cadmium Inorganic materials 0.000 claims description 3
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims description 3
- 239000004745 nonwoven fabric Substances 0.000 claims description 3
- 239000000843 powder Substances 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- 239000004698 Polyethylene Substances 0.000 description 5
- -1 polyethylene Polymers 0.000 description 5
- 229920000573 polyethylene Polymers 0.000 description 5
- 230000000694 effects Effects 0.000 description 2
- 238000005192 partition Methods 0.000 description 2
- 238000001959 radiotherapy Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000000443 aerosol Substances 0.000 description 1
- 239000003708 ampul Substances 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 229920013716 polyethylene resin Polymers 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
Landscapes
- Particle Accelerators (AREA)
- Radiation-Therapy Devices (AREA)
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、主として高エネルギＸ線の放射線治
療室で発生する中性子が該治療室から漏洩するこ
とを防止する遮蔽構造に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shielding structure that prevents neutrons generated in a high-energy X-ray radiation treatment room from leaking from the treatment room.
直線加速器等の高エネルギＸ線発生装置は、該
装置内に線束平坦用フイルタ、コリメータ系、Ｘ
線漏洩防止用遮蔽体を有するが、これらはいずれ
も鉛、タングステン等の高原子番号物質で構成さ
れている。そして該鉛等に高エネルギＸ線を照射
すると、原子核が光子を吸収して中性子を放出す
る現象が生じる。特に8MV以上の直線加速器に
おいては、放射性防護上無視できない中性子発生
量が存在する。即ち、加速器はＸ線の発生源であ
ると共に、中性子の発生源ともなる。このような
中性子を含む放射線源室は一般に放射線遮蔽壁で
囲まれると共に、出入口は迷路状の仕切壁を形成
していた。ところが本発明者の実験によれば、多
くの放射線はこのような仕切壁及び遮蔽壁によつ
て外部に洩れることを阻止できるが、中性子は、
その遮蔽がＸ線に比し困難であり、放射線治療室
から中性子自体の漏洩が生じたり、熱中性子がド
ア等に捕捉されることによりγ線を治療室外へ漏
洩していることがわかつた。
High-energy X-ray generators such as linear accelerators are equipped with a beam flattening filter, a collimator system, and an
It has a shield for preventing radiation leakage, but these are all made of high atomic number materials such as lead and tungsten. When lead or the like is irradiated with high-energy X-rays, a phenomenon occurs in which atomic nuclei absorb photons and emit neutrons. Especially in linear accelerators of 8 MV or higher, the amount of neutrons generated cannot be ignored from the standpoint of radioactivity protection. That is, the accelerator is a source of X-rays as well as a source of neutrons. Such a radiation source chamber containing neutrons is generally surrounded by a radiation shielding wall, and the entrance/exit forms a maze-like partition wall. However, according to the inventor's experiments, although most radiation can be prevented from leaking outside by such partition walls and shielding walls, neutrons are
It has been found that shielding gamma rays is more difficult than for X-rays, and that neutrons themselves leak from the radiation treatment room, and that thermal neutrons are captured by doors and the like, causing gamma rays to leak outside the treatment room.
しかしながらこのような中性子自体の漏洩を防
止する手段は従来全く存在しなかつた。そこで本
発明者はこのような中性子がどこから最も多く漏
洩するか測定した結果、空調用ダクトを介して行
われることがわかつた。これは中性子の挙動に原
因があると思われる。即ち、中性子は直進性もあ
るが、エアーゾルのように霧状の拡散性をも有す
る。このような性質から迷路状に形成されたエア
ーダクトをも迂回して漏洩するものと思われる。
そこで本発明者は上記知見に基づき中性子及びγ
線の漏洩を防ぐことを目的とし、特に空調用ダク
トを介して上記の中性子漏れが生ずるのを阻止す
るものである。 However, there has been no conventional means for preventing such leakage of neutrons themselves. Therefore, the inventor of the present invention measured where the largest number of such neutrons leaked, and as a result, it was found that the leakage occurs through the air conditioning duct. This seems to be caused by the behavior of neutrons. That is, although neutrons have straight propagation properties, they also have mist-like diffusivity like an aerosol. Due to this property, it is thought that the leakage bypasses the air duct formed in a labyrinth shape.
Therefore, based on the above knowledge, the present inventors have determined that neutrons and γ
The purpose is to prevent wire leakage, and in particular to prevent the above-mentioned neutron leakage from occurring through air conditioning ducts.
〔課題を解決するための手段〕
放射線源室の外周を取り囲んだ遮蔽壁３，７
と、その一部の壁に形成された空調ダクト用貫通
口９と、該貫通口９を閉塞するように挿脱自在に
取付けられ、全体が平板状に形成された通気性中
性子遮蔽体１１と、前記貫通口９に取付けられる
空調ダクト１０と、を具備し、前記通気性中性子
遮蔽体１１は、ボロン化合物やカドミウム等の中
性子吸収物質の粉末を合成樹脂に混入させ、その
合成樹脂の粒状体を通気できるように網構造物に
充填し又は、該合成樹脂の不織布のメツシユ構造
としたものからなることを特徴とする中性子を含
む放射線源室の遮蔽構造である。[Means for solving the problem] Shielding walls 3, 7 surrounding the outer periphery of the radiation source room
, an air conditioning duct through-hole 9 formed in a part of the wall, and a breathable neutron shield 11 that is removably attached so as to close the through-hole 9 and has a flat plate shape as a whole. , an air conditioning duct 10 attached to the through hole 9, and the breathable neutron shield 11 is made by mixing a powder of a neutron absorbing substance such as a boron compound or cadmium into a synthetic resin, and forming a granular body of the synthetic resin. This is a shielding structure for a radiation source chamber containing neutrons, characterized in that it is made of a net structure filled with the synthetic resin to allow ventilation, or a mesh structure of a nonwoven fabric of the synthetic resin.
本発明は、第１図〜第２図に示す如く、中性子
線源室１のドア２の部分を除いて、該室１の四周
をコンクリート壁３で囲み、ドア２と高エネルギ
Ｘ線用加速器４との間にコンクリート製の内部遮
蔽壁５を立設する。そしてドア２の内側に両壁
３，５で形成される迂回路６を設け、該迂回路６
の端に厚さ20〜30cm程のポリエチレン製の中性子
遮蔽壁７を立設すると共に、該遮蔽壁７の下部に
ポリエチレン製の内ドア８を取付ける（第３図）。
なお、内ドア８及び中性子遮蔽壁７の表面には鋼
板を貼着する。さらに、該遮蔽壁７の上部に空調
ダクト用貫通口９を設け、（吸気用と換気用の一
対必要であるが図面では換気用を省略する。）該
貫通口９に空調ダクト１０を挿通して該空調ダク
ト１０を第１図の如く配設する。そして第３図の
如く前記貫通口９の位置において空調ダクト１０
内に中性子遮蔽体１１を挿脱自在に配設する。こ
の遮蔽体１１は第４図の如く枠１２の全面及び後
面に金網１３を張設し、両金網１３間にポリエチ
レンチツプ等を充填し、該チツプ間に通気性を保
持させた構造の通気性中性子遮蔽物１４を内装す
る。この遮蔽物１４はボロン化合物B4Cやカドミ
ウム等の中性子吸収性物質の粉末をポリエチレン
等の合成樹脂に混入させたものであり、該ポリエ
チレン等の形状は球状、楕円状のチツプ体であつ
ても、あるいは不織布の如きメツシユ構造等のも
のであつてもよい。そして、枠１２内にそれらを
空調用エアの流通が可能な程度充填する。このよ
うな中性子遮蔽体１１を本実施例では、中性子遮
蔽壁７の幅方向に４枚並列させると共に、空調ダ
クトに前記中性子遮蔽体１１用の取り替え口（図
示せぬ）を設ける。さらに遮蔽壁７の前後で空調
ダクト１０に膨大部１５を設け、中性子遮蔽体１
１の通過時に空調用エアの圧力損失を減ずるもの
とする。
As shown in FIGS. 1 and 2, the present invention is to surround a neutron source chamber 1 with a concrete wall 3 on all four sides, except for the door 2, and to connect the door 2 and a high-energy X-ray accelerator. 4, an internal shielding wall 5 made of concrete is erected. A detour 6 formed by both walls 3 and 5 is provided inside the door 2, and the detour 6 is
A neutron shielding wall 7 made of polyethylene with a thickness of about 20 to 30 cm is erected at the end of the shield wall 7, and an inner door 8 made of polyethylene is attached to the lower part of the shielding wall 7 (FIG. 3).
Note that steel plates are attached to the surfaces of the inner door 8 and the neutron shielding wall 7. Furthermore, a through-hole 9 for an air-conditioning duct is provided in the upper part of the shielding wall 7, and an air-conditioning duct 10 is inserted into the through-hole 9 (a pair of air-conditioning ducts are required, one for intake and one for ventilation, but the one for ventilation is omitted in the drawing). Then, the air conditioning duct 10 is arranged as shown in FIG. As shown in FIG. 3, an air conditioning duct 10 is installed at the position of the through hole 9.
A neutron shield 11 is removably disposed inside. As shown in FIG. 4, this shield 11 has a breathable structure in which a wire mesh 13 is stretched over the entire surface and rear surface of a frame 12, and polyethylene chips or the like are filled between the wire meshes 13 to maintain air permeability between the chips. A neutron shield 14 is installed inside. This shield 14 is made by mixing powder of a neutron-absorbing substance such as a boron compound B 4 C or cadmium into a synthetic resin such as polyethylene, and the shape of the polyethylene is a spherical or elliptical chip. Alternatively, it may have a mesh structure such as a non-woven fabric. Then, they are filled into the frame 12 to the extent that air conditioning air can flow therethrough. In this embodiment, four such neutron shields 11 are arranged in parallel in the width direction of the neutron shield wall 7, and a replacement port (not shown) for the neutron shields 11 is provided in the air conditioning duct. Further, an enlarged portion 15 is provided in the air conditioning duct 10 before and after the shielding wall 7, and the neutron shielding body 1
This shall reduce the pressure loss of the air conditioning air when it passes through.
次に本発明の作用効果について説明する。 Next, the effects of the present invention will be explained.
高エネルギＸ線用加速器４を作動すると、該加
速器４からＸ線と共に中性子が放出される。放出
された中性子は、壁３、内部遮蔽壁５、中性子遮
蔽壁７、内ドア８に遮蔽されて減衰消失するが、
一部の中性子が空調ダクト１０内に飛び込む。し
かしながら、空調ダクト１０内には中性子遮蔽体
１１が壁７の空調ダクト用貫通口９において取付
けられている。そのため、空調ダクト１０内に飛
び込んだ中性子は中性子遮蔽体１１のボロン化合
物、及びポリエチレン樹脂に吸収、遮蔽されて、
二次γ線を放出することなく消減する。なお、中
性子は空調ダクト１０の吹き出し開口から飛び込
む場合と、該空調ダクト１０の外側からその筒体
を突き抜けて該空調ダクト１０内に飛び込む場合
とが存在する。いずれの場合であつても、本発明
の中性子遮蔽体１１が前記壁７の空調ダクト用貫
通口９を閉塞するように配設されているから、中
性子が内部遮蔽壁５よりドア２側に放出すること
は殆どない。一方、中性子遮蔽体１１は通気性の
ある構造を有するから、空調用エアの出入りに支
障はない。しかして、放射線治療室のような中性
子線源室１に空調ダクト１０を適宜配設しても、
該中性子線源室内に中性子が漏洩することなく、
且つ空調機能を阻害することのない中性子遮蔽構
造を提供し得る効果がある。 When the high-energy X-ray accelerator 4 is activated, neutrons are emitted from the accelerator 4 together with X-rays. The emitted neutrons are shielded by the wall 3, internal shielding wall 5, neutron shielding wall 7, and inner door 8, and are attenuated and disappear.
Some of the neutrons fly into the air conditioning duct 10. However, a neutron shield 11 is installed in the air conditioning duct 10 at the air conditioning duct through-hole 9 in the wall 7 . Therefore, the neutrons that entered the air conditioning duct 10 are absorbed and shielded by the boron compound and polyethylene resin of the neutron shield 11.
It disappears without emitting secondary gamma rays. Note that there are two cases in which neutrons fly into the air-conditioning duct 10 from the blow-off opening and into the air-conditioning duct 10 by passing through the cylindrical body from the outside of the air-conditioning duct 10. In either case, since the neutron shield 11 of the present invention is arranged to close the air conditioning duct through-hole 9 of the wall 7, neutrons are emitted from the internal shield wall 5 toward the door 2. There's little to do. On the other hand, since the neutron shielding body 11 has a breathable structure, there is no problem in the inflow and outflow of air conditioning air. However, even if the air conditioning duct 10 is appropriately arranged in the neutron source room 1 such as a radiation therapy room,
No neutrons leak into the neutron source chamber,
Moreover, it is possible to provide a neutron shielding structure that does not impede the air conditioning function.
なお、本発明の中性子を含む放射線源室は上記
実施例に示す放射線治療室のみに限ることなく、
原子炉圧力容器格納室等においても利用し得る。 Note that the radiation source room containing neutrons according to the present invention is not limited to the radiation therapy room shown in the above embodiments.
It can also be used in reactor pressure vessel containment rooms, etc.
第１図は本発明の遮蔽構造を有する放射線源室
の平面図、第２図は第１図のＡ―Ａ線矢視断面
図、第３図は第１図のＢ―Ｂ線矢視断面図、第４
図は中性子遮蔽体の斜視図を示す。
１……中性子線源室、２……ドア、３……壁、
４……高エネルギＸ線用加速器、５……内部遮蔽
壁、６……迂回路、７……中性子遮蔽壁、８……
内ドア、９……空調ダクト用貫通口、１０……空
調ダクト、１１……中性子遮蔽体、１２……枠、
１３……金網、１４……通気性中性子遮蔽物、１
５……膨大部。
FIG. 1 is a plan view of a radiation source chamber having a shielding structure according to the present invention, FIG. 2 is a cross-sectional view taken along the line A--A in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line B--B in FIG. Figure, 4th
The figure shows a perspective view of a neutron shield. 1... Neutron source room, 2... Door, 3... Wall,
4... High energy X-ray accelerator, 5... Internal shielding wall, 6... Detour, 7... Neutron shielding wall, 8...
Inner door, 9... Air conditioning duct penetration, 10... Air conditioning duct, 11... Neutron shield, 12... Frame,
13...wire mesh, 14...breathable neutron shield, 1
5... Ampulla.
Claims (1)
と、その一部の壁に形成された空調ダクト用貫通
口９と、該貫通口９を閉塞するように挿脱自在に
取付けられ、全体が平板状に形成された通気性中
性子遮蔽体１１と、前記貫通口９に取付けられる
空調ダクト１０と、を具備し、前記通気性中性子
遮蔽体１１は、ボロン化合物やカドミユム等の中
性子吸収物質の粉末を合成樹脂に混入させ、その
合成樹脂の粒状体を通気できるように網構造物に
充填し又は、該合成樹脂の不織布のメツシユ構造
としたものからなることを特徴とする中性子を含
む放射線源室の遮蔽構造。1 Shielding walls 3, 7 surrounding the outer periphery of the radiation source room
, an air conditioning duct through-hole 9 formed in a part of the wall, and a breathable neutron shield 11 that is removably attached so as to close the through-hole 9 and has a flat plate shape as a whole. , an air conditioning duct 10 attached to the through hole 9, and the air-permeable neutron shield 11 is made by mixing powder of a neutron absorbing substance such as a boron compound or cadmium into a synthetic resin, and forming a granular body of the synthetic resin. 1. A shielding structure for a radiation source chamber containing neutrons, characterized in that the shielding structure is made of a mesh structure of a non-woven fabric of the synthetic resin filled with the synthetic resin so as to allow ventilation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14144280A JPS5766394A (en) | 1980-10-09 | 1980-10-09 | Neutron shielding body for air-conditioning duct passing through neutron source chamber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14144280A JPS5766394A (en) | 1980-10-09 | 1980-10-09 | Neutron shielding body for air-conditioning duct passing through neutron source chamber |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5766394A JPS5766394A (en) | 1982-04-22 |
| JPH0131160B2 true JPH0131160B2 (en) | 1989-06-23 |
Family
ID=15292032
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14144280A Granted JPS5766394A (en) | 1980-10-09 | 1980-10-09 | Neutron shielding body for air-conditioning duct passing through neutron source chamber |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5766394A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005221118A (en) | 2004-02-04 | 2005-08-18 | Japan Steel Works Ltd:The | Multi-tube heat exchanger |
-
1980
- 1980-10-09 JP JP14144280A patent/JPS5766394A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5766394A (en) | 1982-04-22 |
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