JP4127780B2

JP4127780B2 - Radiation measurement equipment

Info

Publication number: JP4127780B2
Application number: JP2002249850A
Authority: JP
Inventors: 明佐野; 立行前川; 哲夫後藤
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2002-08-29
Filing date: 2002-08-29
Publication date: 2008-07-30
Anticipated expiration: 2022-08-29
Also published as: JP2004085497A

Description

【０００１】
【発明の属する技術分野】
本発明は、電離作用を利用した放射線測定装置に関するもので、特にα線によって電離された空気を電離箱内に移送し、イオン化による電離電流を測定することによりα放射線を測定する放射線測定装置に関する。
【０００２】
【従来の技術】
原子力発電プラントにおいては、プラントの各プロセスにおける放射能を観測して異常の早期発見をしたり、プラント施設及び作業環境の放射能レベルを監視したりするために放射線測定装置が用いられている。
【０００３】
放射線測定装置に使われる放射線検出器にはいろいろな種類のものがあるが、放射線が通過する際に検出器の内部で行われる電離作用を利用して放射線を検出する電離型の検出器が知られている。
【０００４】
これは、放射線を空気に入射させ、放射線により電離した空気を吸引して、電離箱により電離電流値を測定して放射線を求めるもので、α線により電離した空気を吸引して、電離箱でα放射線を求めるという米国特許第5194737号明細書記載の技術が知られている。
【０００５】
上記特許においては、図１２に示すように、イオン化された空気４１がファン４２によって接地された外板４３に囲まれた空間内に吸引され、電源４４によって電圧が印加されたグリッド４５にイオンが収集され、電流計４６によって電離電流を測定することにより放射線の強度、線量、エネルギーが測定される。
【０００６】
このように、α線に対しては、従来閉空間内での電離作用に着目し、その限定された空間内の空気の電離量を測定している。α線１崩壊当たりの電離イオン数は多く、α線の飛程は空気中で約５ｃｍと短いため放射線源近傍の空気が高密度で電離されることから、前記の構成でα放射線が測定可能となる。
【０００７】
【発明が解決しようとする課題】
上記のような従来の電離作用を利用した放射線測定装置は、定められた条件の廃棄物に関する放射線測定には効果的である。しかし、現実に原子力施設で発生する廃棄物は、多種多様であり、これらに対しても放射線を精度よく測定することが望まれている。
本発明は以上の点に鑑み、さらに、簡便に精度よく放射線を測定することのできる放射線測定装置を提供することを目的とする。
【０００８】
【課題を解決するための手段】
上記目的を達成するため請求項１の発明は、放射線を測定すべき測定対象物を収納する測定室と、測定室内の気体を吸引し、気体を測定室内に再循環させる吸引機と、前記気体の再循環経路に設けられ、前記測定対象物の近傍から吸引された気体のイオンを収集する電極部及び収集された前記イオンの電離電流を測定する電流測定手段とからなる電離電流測定装置と、この電離電流測定装置による測定値から放射線量を演算処理するデータ処理装置とを備えた放射線測定装置において、前記電極部は、信号収集用電極板、ガード用電極板及び接地用電極板を 1 組とする３枚の電極板からなり、各電極板は気体透過孔を持つ絶縁基板上に複数の電極が配置されるとともに、前記各電極板を気体の経路に対して基板面が直角となるように配置したことを特徴を特徴とする。
【００１４】
請求項２に記載の発明は、請求項１に記載の放射線測定装置において、信号収集用電極板、ガード用電極板及び接地用電極板を２組以上配置したことを特徴とする。
【００１５】
請求項３に記載の発明は、請求項１又は２記載の放射線測定装置において、再循環経路に、前記測定室内の気体を収束する気体収束手段と、前記測定室内に再循環させた気体の速度を加速する送風機と、加速された気体を前記測定室内に拡散させる気体拡散手段と、を設けたことを特徴とする。
【００１９】
【発明の実施の形態】
以下、本発明の実施の形態を図面を参照して説明する。
本発明の第１の実施の形態による放射線測定装置を図１（ａ）、（ｂ）に示す。図１（ｂ）に示すように、本発明の放射線測定装置は放射線を測定すべき測定対象物１を収納する測定室２と、測定室２の内部の気体を吸引し、測定室２内に再循環させるための吸引機３と、吸引機３により吸引した気体を測定室２内に戻すパイプ４と、再循環される気体中のエアロゾルなどの不純物を吸着するフィルタ５と、測定室２内から吸引され、再循環された気体中のイオンを収集するイオン収集手段６及び収集したイオンの電離電流を測定する電流測定手段７とで構成され、前記気体の再循環経路に設けられた電離電流測定装置８と、データ処理装置９とを備えている。ここで、イオン収集手段６は図１（ａ）に示すように、例えばポリイミド、あるいはフッ素樹脂のような抵抗体として優れた電気的特性を有する材料により形成された絶縁基板１０にストリップ型のアノード電極１１とカソード電極１２とを交互に配置して設けた電極部１３と、アノード電極１１とカソード電極１２とに電圧を印加する電圧供給手段１４とで構成され、この電極部１３は気体が通過する経路の途中に絶縁基板１０が経路を囲むように図示していない固定用絶縁部材により固定し、気体中のイオンをアノード電極１１とカソード電極１２とで収集する。電流測定手段７は、例えばエレクトロメータ、振動容量電位計などの微少電流測定装置を使用する。
【００２０】
以上のような構成において、測定室２の内部の気体を測定対象物１の放射線によりイオン化された電離イオンとともに吸引機３で吸引し、吸引機３を出た気体はパイプ４を通ってフィルタ５に送られ、フィルタ５で不純物粒子を除去した後に、測定室２内に再循環される。この循環過程でイオン収集手段６と電流測定手段７とで構成される電離電流測定装置８により電離電流が測定される。
【００２１】
さらに具体的な測定手段について説明すると、まず、電極部１３のアノード電極１１とカソード電極１２とに電圧供給手段１４より電圧を印加し、測定対象物１が測定室２内に設置されていない状態で、測定室２内の気体を吸引するとともに、吸引気体の電離電流を電離電流測定装置８で測定する。この結果がバックグラウンド電流として、データ処理装置９に記録される。次に、測定室２内に測定対象物１を設置し、測定室２内の気体を吸引するとともに、吸引気体の電離電流を測定し、この結果を信号電流として、データ処理装置９に記録させる。データ処理装置９では、この信号電流値から、前述のバックグランド電流値を減算し正味電流値を求め、この値と、前もって放射線の校正試験により求められた放射線強度と電流値との関係データを使用して、測定対象物１の放射線強度を求める。
【００２２】
このような放射線測定装置によれば、測定対象物１の放射線により電離する気体を吸引機３により吸引して測定室２内に再循環させ、イオン収集手段６に設けられたカソード電極１２とアノード電極１１により気体中に含まれるプラスイオンはカソード電極１２に、マイナスイオンはアノード電極１１に移動、収集される。アノード電極１１とカソード電極１２間の長さ、交互に配置するアノード電極１１とカソード電極１２の数は、測定対象物１の放射線の種類と強度、測定対象物１の寸法、吸引機３の気体吸引率に応じて適切に設定することができる。
【００２３】
このような電極構造による放射線測定装置であると、測定対象物１からの放射線の電離によって生成したイオンが、絶縁基板１０上にストリップ型アノード電極１０とカソード電極１２とを交互に配置し、電圧を印加して設けた電極部１３と電流測定手段７とにより測定されるので、交互に配置された電極によりイオンが効率よく収集され、精度の高い放射線測定を行うことができる。
【００２４】
次に本発明の第２の実施の形態による放射線測定装置を図２（ａ）、（ｂ）に示す。すなわち、この実施の形態によれば、図２（ａ）に示すように、イオン収集手段として、絶縁基板１０上にカソード電極１２、ガード電極１５、アノード電極１１、ガード電極１５、カソード電極１２、ガード電極１５の順番で電極を配置した電極部１３を図２（ｂ）に示すように、気体が通過する経路の途中のイオン収集手段６の空間内に絶縁基板１０が経路を囲むように図示していない固定用絶縁材により固定している。ここで、例えば、カソード電極１２を接地電極とし、電圧供給手段１４によりガード電極１５に正の電圧を印加し、アノード電極１１とガード電極１５間の電流を電流測定手段７で測定する。
【００２５】
このような電極構造による放射線測定装置であると、イオン収集のため印加した電圧による漏れ電流はガード電極１５とカソード電極１２間を流れる。一方、アノード電極１１とガード電極１５間には、印加電圧による漏れ電流は発生せず、気体中のイオンによる電離電流のみが測定される。従って、ガード電極１５を用いた電極により、漏れ電流の影響を省き、高効率でイオンを収集することができる。このような、ガード電極１５を備えた電極部１３をイオン収集手段６の内面に設置することにより、流通する気体中のイオンを漏れ電流が少なく、高効率で測定でき、その結果、精度よく放射線を測定することができる。
【００２６】
次に本発明の第３の実施の形態による放射線測定装置を図３に示す。すなわち、この実施の形態によれば、イオン収集手段６は、絶縁基板上にアノード電極とカソード電極とを交互に配置した電極部１３、あるいは、絶縁基板上にカソード電極、ガード電極、アノード電極、ガード電極、カソード電極、ガード電極の順番で電極を配置した電極部１３を気体が通過する経路の途中のイオン収集手段６の空間内に絶縁基板１０が経路と並行となるように図示していない固定用絶縁材により固定し、気体中のイオンを収集する。
【００２７】
このように、イオンを収集する電極部１３を、流動する気体が存在するイオン収集手段６の空間内に配置するので、測定対象物１のイオンに電極を近づけることができ、効率よくイオンを収集することができる。その結果、感度が上がり、精度よく放射線を測定することができる。
【００２８】
次に本発明の第４の実施の形態による放射線測定装置を図４に示す。すなわち、この実施の形態によれば、イオン収集手段６は、絶縁基板上にアノード電極とカソード電極とを交互に配置した電極部１３、あるいは、絶縁基板上にカソード電極、ガード電極、アノード電極、ガード電極、カソード電極、ガード電極の順番で電極を配置した電極部１３を、気体が通過する経路の途中のイオン収集部６の内面に絶縁基板１０が経路を囲むように、また、気体が流通する空間内に絶縁基板１０が経路と並行になるように図示していない固定用絶縁材によりＨ型配置となるように固定し、気体中のイオンを収集する。
【００２９】
このように、イオンを収集する電極部１３を、流動する気体の経路を囲むように、また経路の空間に配置するので、収集対象物１のイオンに電極をさらに近接することができ、効率よくイオンを収集することができる。その結果、感度が上がり、精度よく放射線を測定することができる。
【００３０】
次に本発明の第５の実施の形態による放射線測定装置を図５（ａ）、（ｂ）に示す。すなわちこの実施の形態によれば、図５（ａ）に示すように絶縁基板１０上に複数の電極１６を配置し、配置した電極１６間の絶縁基板１０に気体が通過し易くなるように、気体通過孔１７を形成し、図５（ｂ）に示すように気体の通過領域に前もって定めた間隔で３枚で１組を成す少なくとも１組以上の絶縁基板１０を基板面が気体の通過方向に対して直角になるように配置する。各電極板の電極は電気的に接続されており、これらを測定室２側から並べて、信号収集用電極板１８、ガード用電極板１９、接地用電極板２０として使用する。接地用電極板２０は接地し、電圧供給手段１４によりガード用電極板１９と接地用電極板２０にはプラスの電圧を印加する。そして、信号用電極板１８とガード用電極板１９との電流を電流測定手段７により測定する。ここで、電圧はガード用電極板１９と接地用電極板２０間に印加されているので、これによる漏れ電流の影響を受けずに、空気中のイオンを検出することができる。
【００３１】
以上のようなイオン収集手段の条件で、測定室２内の気体を吸引機３で吸引すると測定室２内の放射線によって電離された気体は吸引されて、イオン収集手段６内を通過する。ここで、各絶縁基板１０に開けられた気体貫通孔１７を気体が通過するが、イオンが信号収集用電極板１８とガード用電極板１９の間に存在するときに、イオンを高い効率で電極板１３に収集することができる。収集されたイオンは、電流測定手段７により、電離電流として測定され、データ処理装置９により測定した電流値から放射線強度が測定されるので、高効率、高精度で放射線を測定することができる。
【００３２】
以上のような基本機能に加え、各電極板の間隔、気体通過孔１７の寸法、各電極板間の設定寸法は任意に設定可能な構造とし、吸引機３の気体吸引容量、印加電圧、放射線強度、測定室２及びイオン収集手段６の内面寸法に応じて、前記の任意設定可能寸法を適切に設定し、測定精度、検出感度を向上する。
【００３３】
次に本発明の第６の実施の形態による放射線測定装置を図６（ａ）、（ｂ）に示す。すなわちこの実施の形態によれば、図６（ａ）に示すように、図示しないが多数の気体通過孔を形成した絶縁基板２２の両面に例えば金属の導体を配置した電極板で、絶縁基板２２の気体通過孔と同じ位置に多数の気体通過孔１７を備えた電極板２１を、図６（ｂ）に示すように、イオン収集手段６の気体通過空間に電極板を気体の経路に対して基板面が直角となるように、すなわち、気体通過孔１７の中心軸が気体の経路とほぼ同様な方向となるように配置する。この電極板２１間に電圧を印加する電圧供給手段１４に接続するとともに、この間の電流を測定するように電流測定手段７を接続する。このような構成で、測定室２に測定対象物１を設置し、測定室２内の気体を吸引機３で吸引すると、イオン収集手段６の電極板２１の気体貫通孔１７をこの気体が通過する時に、気体中のイオンは気体貫通孔１７の入口及び出口の近傍の電極にイオンは収集される。気体貫通孔１７が、多数設けられていれば、気体の流量をそれほど大きく減少させることなく通過させることができ、これらの近傍の電極でイオンを効率的に収集することができる。
このように、効率よくイオンを収集できるので、その結果感度が上がり、精度よく放射線を測定することができる。
【００３４】
次に本発明の第７の実施の形態による放射線測定装置を図７に示す。すなわちこの実施の形態によれば、測定対象物１を収納する測定室２と、測定室２内の気体を収束して吸引するように例えば吸引口方向に向かって気体を収束させるよう配置された多層の円錐プレートで構成される気体収束手段２３と、測定室２内の気体をパイプ４を介して吸引する吸引機３と、パイプ４の途中に設けられ気体のイオンを収集し電離電流を測定する電離電流測定装置８と、データ処理装置９と、吸引した気体をパイプ４とフィルタ５を介して測定室２内に再循環させる再循環系統と、測定室２内に注入した気体の速度を加速する送風機２４と、加速された気体を例えば測定室２の吸引口方向に向かって気体を拡散させるよう配置された多層の円錐プレートで構成される流体拡散手段２５で構成される。
【００３５】
このような構成の放射線測定装置において、測定対象部１から放出される放射線により電離された気体は、送風機２４と気体拡散手段２５により、測定室２の吸引口方向に向かって移動し、さらに気体収束手段２３により吸引口に向かって移動される。このように、生成したイオンが吸引口方向に向かうように強制的に気体の流れを作るので、効率的に、しかもイオン生成位置による移送効率差を少なくすることができる。吸引口に達した気体は、パイプ４を経て電離電流測定装置８に入り、ここでイオンが電離電流として測定され、電流値からデータ処理装置９により放射線が測定される。電離電流測定装置８を通過した気体は、吸引機３、パイプ４、フィルタ５を経て、測定室２内に再循環される。ここで、測定室２内に入った気体は、送風機２４により加速され、前記のような手順の操作が繰り返される。以上記したように、測定室２内の気体を再循環させることにより、空気中に存在するラドン・トロンの放射性崩壊に伴うイオンの生成、空気中に存在するイオン、空気中の湿度、温度などの影響が減少し、測定精度、感度が向上する。また、送風機２４、気体拡散手段２５、気体収束手段２３により、測定室２内のイオン移送効率の向上とともに、効率差を減少することができ、測定感度と精度を向上することができる。
【００３６】
次に本発明の第８の実施の形態による放射線測定装置を図８に示す。すなわちこの実施の形態によれば、放射能の汚染の有無を測定すべき被検体を収容する測定室２と、測定室２内の気体を気体吸引口２６に向かって移送する送風機２４と、右手を収納してその周囲の気体を吸引する右手用気体吸引口２７と、左手用気体吸引口２８と、靴底用気体吸入口２９と、被検体の近傍を通過した空気を吸引する少なくとも２個以上の気体吸引口２６と、各気体吸引口２６に対応して接続された電離電流測定装置８と、測定された各位置の電離電流計値を演算処理して被検体各部の放射線量を演算処理するデータ処理装置９と、その表示装置３０で構成される。
【００３７】
このような構成において、放射能汚染を検査する被検体を測定室２に入れ、送風機２４により被検体近傍に気体を送ると、仮に被検体に放射能汚染があった場合には、その汚染場所から放出される放射線により気体は電離される。被検体の各部位近傍で生成したイオンは、送風機２４により各部位に対応する各々の気体吸引口２６に向かって移送され、吸引機３により吸引される。これらの気体吸引口２６に対応して設けられた電離電流測定装置８によりイオンが測定される。測定された各電流値はデータ処理装置９により、換算定数を使用して被検体各部の放射能強度に変換され、表示装置３０により、各部の放射能強度が表示される。
【００３８】
このように、測定対象とする被検体の左手、右手、靴底、少なくとも２個以上に領域分けした被検体の各部の電離電流を精度よく測定することができる。従って、前記被検体各部の放射能汚染を精度よく測定することができる。
【００３９】
次に本発明の第９の実施の形態による放射線測定装置を図９に示す。すなわちこの実施の形態によれば図９（ｂ）に示すように、放射能の汚染の有無を測定すべき被検体を収納する排気口３１付の測定室２と、右手用の電離電流測定装置３２と、左手用電離電流測定装置３３と、靴底用電離電流測定装置３４と、測定室２内に均等に気体を送る多数の気体噴出口３５及び気体圧縮手段３６で構成される送風機２４と、図９（ａ）に示すようにアノード電極１１とカソード電極１２とを交互に配置した誘電板３８と、前記アノード電極１１、カソード電極１２に直交する少なくとも２個以上のバックストリップ電極３７とを有する２次元電離電流測定装置と、測定した電流値から被検体各部の放射線量を演算処理するデータ処理装置と、その表示装置３０で構成される。
【００４０】
このような構成において、放射能汚染を検査する被検体を測定室２内に入れ、例えば、コンプレッサのような気体圧縮手段３６により圧縮された気体を多数の気体噴出口３５より被検体に向かって直角に噴出させる。
【００４１】
仮に被検体に放射能汚染があった場合には、その汚染場所から放出される放射線により気体は電離され、生成したイオンは、前記の２次元電離電流測定装置３９の方向に向かい、この２次元電離電流測定装置３９で電流値の２次元分布が測定される。
【００４２】
ここで、データ処理装置９により、前もって求めた被検体の各部位の位置と２次元電離電流測定装置３９の２次元位置の対応関係を使用して、測定した電流値の２次元分布から被検体の各部の汚染放射能分布を求める。このようにして、被検体の汚染状況の２次元分布を精度よく測定することができる。
【００４３】
これにより、測定対象とする被検体の左手、右手、靴底、２次元に領域分けした被検体の部分の電流を精度よく測定することができる。従って、前記被検体各部の放射能を精度よく測定することができる。
【００４４】
次に本発明の第１０の実施の形態による放射線測定装置を図１０（ａ）、（ｂ）に示す。すなわちこの実施の形態によれば、図１０（ｂ）に示すように、測定位置の近傍に設置した少なくとも２個以上の気体吸引口２９と、これらを接続するパイプ４と、各パイプ４から電離電流測定装置８に送る気体を切替える例えば電磁バルブのような切替手段４０と、各気体吸引口２９の電離電流測定値から放射線量を演算処理するデータ処理装置９と、気体吸引口２９に対応して放射線測定結果を表示する表示装置３０と、図１０（ａ）に示すように絶縁基板１０上にストリップ型のアノード電極１１とカソード電極１２とを交互に配置した電極部１３、あるいは絶縁基板１０上にストリップ型のアノード電極１１、ガード電極１５、カソード電極１２、ガード電極１５、アノード電極１１、ガード電極１５の順番で電極を配置した電極部などを使用した電離電流測定装置８で構成される。
【００４５】
この構成において、切替手段４０により、気体吸引口２９の接続を順次切替え、それぞれの吸引口近傍の気体を吸引機３で吸引しつつ、電離電流測定装置８で電離電流を測定する。測定した電流値と前もって求めた電流値とから放射線強度への換算定数を使用して、各吸引口近傍の放射線強度を求める。このような測定を行えば、効率的にしかも精度よく、測定対象とする場所の放射線強度を測定することができる。
【００４６】
次に本発明の第１１の実施の形態による放射線測定装置を図１１（ａ）、（ｂ）に示す。すなわち図１１（ｂ）に示すように、測定対象物１の表面に直面する面２ａを開放した測定室２と、図１１（ａ）に示すように測定室２の内面に取り付けたアノード電極１１とカソード電極１２とを交互に配置した電極部１３と、この電極部１３に電圧を印加する電圧印加手段１４と、電極が収集したイオンを電離電流として測定する電流測定手段７と、測定した電流値から放射線量を演算処理するデータ処理装置９で構成される。
【００４７】
測定対象物１の表面近傍に、測定室２の開口部２ａを近接あるいは密着させると、測定室２内の空間２ｄを、測定対象物１の表面で閉塞することになり、測定対象物１の表面の放射性核種から放出された放射線の電離で生成したイオンは、前記空間内に一定の寿命で滞在する。この空間２ｄは、例えば、α線の場合には、空気中の飛程が約５ｃｍということから、測定室２の空間２ｄの厚さを５ｃｍ程度に設定すると、電極部１３近傍には生成したイオンが存在する。このイオンを前記電極部１３で効率的に収集し、電流測定手段１２で電流を測定し、データ処理装置９により測定した電流から換算定数を使用して放射線を測定する。
このように、簡便な装置構成で放射能を精度よく測定することができる。
【００４８】
【発明の効果】
以上のように本発明によれば、簡便に精度よく、かつ高効率で放射能を測定することのできる放射線測定装置を得ることができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態による放射能測定装置の構成を示す図で、（ａ）は電極部分詳細図、（ｂ）は全体斜視図。
【図２】本発明の第２の実施の形態による放射能測定装置の構成を示す図で、（ａ）は電極部分詳細図、（ｂ）は全体斜視図。
【図３】本発明の第３の実施の形態による放射能測定装置の構成を示す全体斜視図。
【図４】本発明の第４の実施の形態による放射能測定装置の構成を示す全体斜視図。
【図５】本発明の第５の実施の形態による放射能測定装置の構成を示す図で、（ａ）は電極部分詳細図、（ｂ）は全体斜視図。
【図６】本発明の第６の実施の形態による放射能測定装置の構成を示す図で、（ａ）は電極部分詳細図、（ｂ）は全体斜視図。
【図７】本発明の第７の実施の形態による放射能測定装置の構成を示す正面図。
【図８】本発明の第８の実施の形態による放射能測定装置の構成を示す正面図。
【図９】本発明の第９の実施の形態による放射能測定装置の構成を示す図で、（ａ）は電極部分詳細図、（ｂ）は正面図。
【図１０】本発明の第１０の実施の形態による放射能測定装置の構成を示す図で、（ａ）は電極部分詳細図、（ｂ）は正面図。
【図１１】本発明の第１１の実施の形態による放射能測定装置の構成を示す図で、（ａ）は電極部分詳細図、（ｂ）は正面図。
【図１２】従来の放射線測定装置を示す概略構成図。
【符号の説明】
１…測定対象物、２…測定室、３…吸引機、４…パイプ、５…フィルタ、６…イオン収集手段、７…電流測定手段、８…電離電流測定装置、９…データ処理装置、１０…基板、１１…アノード電極、１２…カソード電極、１３…電極部、１４…電圧供給手段、１５…ガード電極、１６…電極、１７…気体貫通孔、１８…信号収集電極、１９…ガード電極、２０…接地電極、２１…電極板、２２…絶縁材、２３…気体収束手段、２４…送風機、２５…気体拡散手段、２６…気体吸引口、２７…右手用気体吸引口２８…左手用気体吸引口、２９…靴底用気体吸引口、３０…表示装置、３１…排気口、３２…右手用電離電流測定装置、３３…左手用電離電流測定装置、３４…靴底用電離電流測定装置、３５…多数気体吸引口、３６…気体圧縮手段、３７…バックストリップ、３８…誘電版、３９…２次元電離電流測定装置、４０…切替手段。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radiation measurement apparatus using an ionization action, and more particularly to a radiation measurement apparatus that measures α radiation by transferring ionized current by ionization into an ionization chamber and measuring ionization current by ionization. .
[0002]
[Prior art]
In a nuclear power plant, a radiation measuring device is used for observing the radioactivity in each process of the plant to detect an abnormality at an early stage and monitoring the radioactivity level of the plant facility and the work environment.
[0003]
There are various types of radiation detectors used in radiation measurement devices, but ionization-type detectors that detect radiation using the ionization action that occurs inside the detector when radiation passes are known. It has been.
[0004]
In this method, radiation is incident on the air, the air ionized by the radiation is sucked, the ionization current value is measured by the ionization chamber, and the radiation is obtained. The ionized air is sucked by the α-ray and the ionization chamber is used. A technique described in US Pat. No. 5,194,737 for obtaining α radiation is known.
[0005]
In the above patent, as shown in FIG. 12, ionized air 41 is sucked into a space surrounded by an outer plate 43 grounded by a fan 42, and ions are applied to a grid 45 to which a voltage is applied by a power supply 44. The intensity of the radiation, the dose, and the energy are measured by collecting and measuring the ionization current by the ammeter 46.
[0006]
As described above, with respect to α rays, the ionization amount in the limited space is measured by focusing on the ionization effect in the closed space. Since the number of ionized ions per α-ray decay is large and the range of α-rays is as short as about 5 cm in the air, the air near the radiation source is ionized at high density, so α radiation can be measured with the above configuration. It becomes.
[0007]
[Problems to be solved by the invention]
The conventional radiation measuring apparatus using the ionizing action as described above is effective for measuring radiation related to waste under a predetermined condition. However, there are a wide variety of wastes actually generated at nuclear facilities, and it is desired to measure radiation with high accuracy for these wastes.
In view of the above points, an object of the present invention is to provide a radiation measuring apparatus that can easily and accurately measure radiation.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 includes a measurement chamber for storing a measurement object whose radiation is to be measured, a suction device for sucking a gas in the measurement chamber and recirculating the gas into the measurement chamber, and the gas. An ionization current measuring device, which is provided in the recirculation path, and includes an electrode unit that collects gas ions sucked from the vicinity of the measurement object, and a current measurement unit that measures the ionization current of the collected ions , a radiation measuring device comprising a data processing device for processing the radiation dose from the value measured by the ionization current measuring device, the electrode portion, the signal collecting electrode plates, the electrode plates and the ground electrode plate guard set And each electrode plate is arranged on an insulating substrate having a gas permeable hole, and the electrode surface of each electrode plate is perpendicular to the gas path. Placed in And features.
[0014]
According to a second aspect of the invention, the radiation measuring device according to claim 1, the signal collecting electrode plates, characterized in that a electrode plate and the ground electrode plate guard two or more pairs.
[0015]
The invention according to claim 3 is the radiation measuring apparatus according to claim 1 or 2 , wherein the gas converging means for converging the gas in the measurement chamber in the recirculation path, and the velocity of the gas recirculated in the measurement chamber. And a gas diffusion means for diffusing the accelerated gas into the measurement chamber.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A radiation measuring apparatus according to a first embodiment of the present invention is shown in FIGS. As shown in FIG. 1 (b), the radiation measuring apparatus of the present invention sucks the gas in the measuring chamber 2 that houses the measuring object 1 to be measured for radiation and the measuring chamber 2, and enters the measuring chamber 2. A suction machine 3 for recirculation, a pipe 4 for returning the gas sucked by the suction machine 3 into the measurement chamber 2, a filter 5 for adsorbing impurities such as aerosol in the recirculated gas, and the measurement chamber 2 An ion collecting means 6 for collecting ions in the gas that has been sucked and recirculated, and a current measuring means 7 for measuring the ionization current of the collected ions, and provided in the gas recirculation path A measuring device 8 and a data processing device 9 are provided. Here, as shown in FIG. 1A, the ion collecting means 6 is a strip-type anode formed on an insulating substrate 10 formed of a material having excellent electrical characteristics such as a resistor such as polyimide or fluororesin. The electrode unit 13 is provided with electrodes 11 and cathode electrodes 12 arranged alternately, and voltage supply means 14 for applying a voltage to the anode electrode 11 and the cathode electrode 12, and gas passes through the electrode unit 13. The insulating substrate 10 is fixed by a fixing insulating member (not shown) so as to surround the path in the middle of the path to be collected, and ions in the gas are collected by the anode electrode 11 and the cathode electrode 12. The current measuring means 7 uses a minute current measuring device such as an electrometer or a vibration capacitance potentiometer.
[0020]
In the configuration as described above, the gas inside the measurement chamber 2 is sucked by the suction machine 3 together with the ionized ions ionized by the radiation of the measurement object 1, and the gas exiting the suction machine 3 passes through the pipe 4 and passes through the filter 5. After the impurity particles are removed by the filter 5, they are recirculated in the measurement chamber 2. In this circulation process, the ionizing current is measured by the ionizing current measuring device 8 constituted by the ion collecting means 6 and the current measuring means 7.
[0021]
More specific measurement means will be described. First, a voltage is applied from the voltage supply means 14 to the anode electrode 11 and the cathode electrode 12 of the electrode section 13, and the measurement object 1 is not installed in the measurement chamber 2. Thus, the gas in the measurement chamber 2 is sucked, and the ionization current of the suction gas is measured by the ionization current measuring device 8. This result is recorded in the data processor 9 as a background current. Next, the measurement object 1 is installed in the measurement chamber 2, the gas in the measurement chamber 2 is sucked, the ionization current of the suction gas is measured, and this result is recorded in the data processing device 9 as a signal current. . The data processing device 9 subtracts the above-mentioned background current value from this signal current value to obtain a net current value, and obtains the relationship data between this value and the radiation intensity and current value obtained in advance by a radiation calibration test. Used to determine the radiation intensity of the measurement object 1.
[0022]
According to such a radiation measuring apparatus, the gas ionized by the radiation of the measuring object 1 is sucked by the suction device 3 and recirculated into the measuring chamber 2, and the cathode electrode 12 and the anode provided in the ion collecting means 6 The positive ions contained in the gas are moved to and collected by the cathode electrode 12 and the negative ions are moved to the anode electrode 11 by the electrode 11. The length between the anode electrode 11 and the cathode electrode 12, the number of the anode electrodes 11 and the cathode electrodes 12 arranged alternately, the type and intensity of the radiation of the measurement object 1, the dimensions of the measurement object 1, the gas of the suction device 3 It can be set appropriately according to the suction rate.
[0023]
In the radiation measuring apparatus having such an electrode structure, ions generated by ionization of radiation from the measurement target 1 alternately arrange the strip-type anode electrodes 10 and the cathode electrodes 12 on the insulating substrate 10, and voltage Is measured by the electrode portion 13 and the current measuring means 7 provided by applying ion, so that ions are efficiently collected by the alternately arranged electrodes, and highly accurate radiation measurement can be performed.
[0024]
Next, a radiation measuring apparatus according to the second embodiment of the present invention is shown in FIGS. That is, according to this embodiment, as shown in FIG. 2A, as an ion collecting means, a cathode electrode 12, a guard electrode 15, an anode electrode 11, a guard electrode 15, a cathode electrode 12, As shown in FIG. 2B, the electrode portion 13 in which the electrodes are arranged in the order of the guard electrodes 15 is shown so that the insulating substrate 10 surrounds the path in the space of the ion collecting means 6 in the middle of the path through which the gas passes. It is fixed with an insulating material not shown. Here, for example, the cathode electrode 12 is a ground electrode, a positive voltage is applied to the guard electrode 15 by the voltage supply means 14, and the current between the anode electrode 11 and the guard electrode 15 is measured by the current measurement means 7.
[0025]
In the radiation measuring apparatus having such an electrode structure, leakage current due to the voltage applied for ion collection flows between the guard electrode 15 and the cathode electrode 12. On the other hand, no leakage current due to the applied voltage is generated between the anode electrode 11 and the guard electrode 15, and only the ionization current due to ions in the gas is measured. Therefore, the electrode using the guard electrode 15 can collect ions with high efficiency while eliminating the influence of leakage current. By installing the electrode part 13 having the guard electrode 15 on the inner surface of the ion collecting means 6 as described above, it is possible to measure ions in the flowing gas with low leakage current and high efficiency. Can be measured.
[0026]
Next, FIG. 3 shows a radiation measuring apparatus according to the third embodiment of the present invention. That is, according to this embodiment, the ion collecting means 6 includes an electrode portion 13 in which anode electrodes and cathode electrodes are alternately arranged on an insulating substrate, or a cathode electrode, a guard electrode, an anode electrode, The insulating substrate 10 is not shown in parallel with the path in the space of the ion collecting means 6 in the middle of the path through which the gas passes through the electrode portion 13 in which the electrodes are arranged in the order of the guard electrode, the cathode electrode, and the guard electrode. Fixing with fixing insulating material and collecting ions in gas.
[0027]
Thus, since the electrode part 13 which collects ions is arranged in the space of the ion collecting means 6 where the flowing gas exists, the electrode can be brought close to the ions of the measurement object 1 and ions are efficiently collected. can do. As a result, sensitivity is improved and radiation can be measured with high accuracy.
[0028]
Next, a radiation measuring apparatus according to a fourth embodiment of the present invention is shown in FIG. That is, according to this embodiment, the ion collecting means 6 includes an electrode portion 13 in which anode electrodes and cathode electrodes are alternately arranged on an insulating substrate, or a cathode electrode, a guard electrode, an anode electrode, In the electrode part 13 in which the electrodes are arranged in the order of the guard electrode, the cathode electrode, and the guard electrode, the insulating substrate 10 surrounds the path on the inner surface of the ion collecting part 6 in the middle of the path through which the gas passes, and the gas flows. The insulating substrate 10 is fixed in an H-type arrangement by a fixing insulating material (not shown) so that the insulating substrate 10 is parallel to the path, and ions in the gas are collected.
[0029]
Thus, since the electrode part 13 for collecting ions is arranged so as to surround the path of the flowing gas and in the space of the path, the electrode can be further brought closer to the ions of the collection target 1 and efficiently. Ions can be collected. As a result, sensitivity is improved and radiation can be measured with high accuracy.
[0030]
Next, a radiation measuring apparatus according to a fifth embodiment of the present invention is shown in FIGS. That is, according to this embodiment, as shown in FIG. 5A, a plurality of electrodes 16 are arranged on the insulating substrate 10 so that gas can easily pass through the insulating substrate 10 between the arranged electrodes 16. A gas passage hole 17 is formed, and as shown in FIG. 5 (b), at least one set of the insulating substrates 10 forming a set of three at a predetermined interval in the gas passage region, the substrate surface is in the gas passage direction. It is arranged so as to be perpendicular to The electrodes of each electrode plate are electrically connected. These are arranged from the measurement chamber 2 side and used as the signal collecting electrode plate 18, the guard electrode plate 19, and the ground electrode plate 20. The ground electrode plate 20 is grounded, and a positive voltage is applied to the guard electrode plate 19 and the ground electrode plate 20 by the voltage supply means 14. Then, the current measurement means 7 measures the current between the signal electrode plate 18 and the guard electrode plate 19. Here, since the voltage is applied between the guard electrode plate 19 and the ground electrode plate 20, ions in the air can be detected without being affected by the leakage current.
[0031]
When the gas in the measurement chamber 2 is sucked by the suction device 3 under the conditions of the ion collecting means as described above, the gas ionized by the radiation in the measurement chamber 2 is sucked and passes through the ion collecting means 6. Here, gas passes through the gas through-holes 17 formed in each insulating substrate 10, but when ions are present between the signal collecting electrode plate 18 and the guard electrode plate 19, the ions are electroded with high efficiency. It can be collected on a plate 13. The collected ions are measured as an ionization current by the current measuring means 7 and the radiation intensity is measured from the current value measured by the data processing device 9, so that the radiation can be measured with high efficiency and high accuracy.
[0032]
In addition to the basic functions as described above, the distance between the electrode plates, the size of the gas passage hole 17, and the set size between the electrode plates can be arbitrarily set, and the gas suction capacity, applied voltage, radiation of the suction machine 3 can be set. The arbitrarily settable dimensions are appropriately set according to the strength, the inner dimensions of the measurement chamber 2 and the ion collecting means 6 to improve measurement accuracy and detection sensitivity.
[0033]
Next, a radiation measuring apparatus according to a sixth embodiment of the present invention is shown in FIGS. That is, according to this embodiment, as shown in FIG. 6A, the insulating substrate 22 is an electrode plate in which, for example, metal conductors are arranged on both surfaces of the insulating substrate 22 in which a large number of gas passage holes are formed. The electrode plate 21 having a large number of gas passage holes 17 at the same position as the gas passage holes of FIG. 6B is arranged in the gas passage space of the ion collecting means 6 with respect to the gas path as shown in FIG. It arrange | positions so that a board | substrate surface may become a right angle, ie, the center axis | shaft of the gas passage hole 17 may become the direction substantially the same as a gas path | route. While connecting to the voltage supply means 14 which applies a voltage between this electrode plate 21, the current measurement means 7 is connected so that the electric current in the meantime may be measured. With such a configuration, when the measurement object 1 is installed in the measurement chamber 2 and the gas in the measurement chamber 2 is sucked by the suction device 3, the gas passes through the gas through holes 17 of the electrode plate 21 of the ion collecting means 6. At this time, ions in the gas are collected at electrodes near the inlet and outlet of the gas through-hole 17. If a large number of gas through-holes 17 are provided, the gas flow rate can be allowed to pass through without being greatly reduced, and ions can be efficiently collected at the electrodes in the vicinity thereof.
As described above, since ions can be collected efficiently, the sensitivity increases as a result, and the radiation can be measured with high accuracy.
[0034]
Next, a radiation measuring apparatus according to a seventh embodiment of the present invention is shown in FIG. That is, according to this embodiment, the measurement chamber 2 that houses the measurement object 1 and the gas in the measurement chamber 2 are arranged so as to converge, for example, toward the suction port so as to converge and suck the gas in the measurement chamber 2. A gas converging means 23 composed of a multi-layered conical plate, a suction device 3 for sucking the gas in the measurement chamber 2 through the pipe 4, and collecting ion ions in the middle of the pipe 4 to measure the ionization current The ionizing current measuring device 8, the data processing device 9, the recirculation system for recirculating the sucked gas into the measuring chamber 2 through the pipe 4 and the filter 5, and the velocity of the gas injected into the measuring chamber 2. An air blower 24 that accelerates and a fluid diffusion means 25 composed of a multi-layered conical plate arranged to diffuse the accelerated gas toward the suction port of the measurement chamber 2, for example.
[0035]
In the radiation measuring apparatus having such a configuration, the gas ionized by the radiation emitted from the measurement target unit 1 is moved toward the suction port of the measurement chamber 2 by the blower 24 and the gas diffusing means 25, and further the gas. It is moved toward the suction port by the converging means 23. In this way, the gas flow is forcibly created so that the generated ions are directed in the direction of the suction port, so that the difference in transfer efficiency depending on the ion generation position can be reduced efficiently. The gas that has reached the suction port enters the ionization current measuring device 8 through the pipe 4, where ions are measured as an ionization current, and radiation is measured by the data processing device 9 from the current value. The gas that has passed through the ionization current measuring device 8 is recirculated into the measurement chamber 2 through the suction device 3, the pipe 4, and the filter 5. Here, the gas that has entered the measurement chamber 2 is accelerated by the blower 24, and the above-described procedure is repeated. As described above, by recirculating the gas in the measurement chamber 2, generation of ions accompanying the radioactive decay of radon and thoron existing in the air, ions existing in the air, humidity in the air, temperature, etc. The measurement accuracy and sensitivity are improved. Further, the blower 24, the gas diffusion means 25, and the gas converging means 23 can improve the ion transfer efficiency in the measurement chamber 2, reduce the efficiency difference, and improve the measurement sensitivity and accuracy.
[0036]
Next, a radiation measuring apparatus according to an eighth embodiment of the present invention is shown in FIG. That is, according to this embodiment, the measurement chamber 2 that houses the subject to be measured for the presence or absence of radioactive contamination, the blower 24 that transfers the gas in the measurement chamber 2 toward the gas suction port 26, and the right hand A right-hand gas suction port 27 for sucking the surrounding gas, a left-hand gas suction port 28, a shoe-sole gas suction port 29, and at least two for sucking air that has passed through the vicinity of the subject. The above-described gas suction port 26, the ionization current measuring device 8 connected corresponding to each gas suction port 26, and the ionization ammeter value at each measured position are processed to calculate the radiation dose of each part of the subject. It comprises a data processing device 9 for processing and a display device 30 for the data processing device 9.
[0037]
In such a configuration, when a subject to be examined for radioactive contamination is placed in the measurement chamber 2 and gas is sent to the vicinity of the subject by the blower 24, if the subject is radioactively contaminated, the contamination location The gas is ionized by the radiation emitted from. Ions generated in the vicinity of each part of the subject are transferred by the blower 24 toward each gas suction port 26 corresponding to each part and sucked by the suction machine 3. Ions are measured by the ionization current measuring device 8 provided corresponding to these gas suction ports 26. Each measured current value is converted into the radioactivity intensity of each part of the subject by using the conversion constant by the data processing device 9, and the radioactivity intensity of each part is displayed by the display device 30.
[0038]
As described above, the ionization current of each part of the subject divided into at least two regions, that is, the left hand, the right hand, and the shoe sole of the subject to be measured can be accurately measured. Therefore, the radioactive contamination of each part of the subject can be accurately measured.
[0039]
Next, a radiation measuring apparatus according to a ninth embodiment of the present invention is shown in FIG. That is, according to this embodiment, as shown in FIG. 9 (b), the measurement chamber 2 with the exhaust port 31 for storing the subject to be measured for the presence or absence of radioactive contamination, and the ionization current measuring device for the right hand 32, an ionization current measurement device 33 for the left hand, an ionization current measurement device 34 for the shoe sole, and a blower 24 composed of a number of gas jets 35 and a gas compression means 36 for sending gas evenly into the measurement chamber 2. As shown in FIG. 9A, dielectric plates 38 in which anode electrodes 11 and cathode electrodes 12 are alternately arranged, and at least two or more back strip electrodes 37 orthogonal to the anode electrodes 11 and cathode electrodes 12 are provided. A two-dimensional ionization current measuring device, a data processing device for calculating the radiation dose of each part of the subject from the measured current value, and a display device 30 thereof.
[0040]
In such a configuration, a subject to be examined for radioactive contamination is placed in the measurement chamber 2, and for example, the gas compressed by the gas compression means 36 such as a compressor is directed to the subject from a number of gas jets 35. It is ejected at a right angle.
[0041]
If the subject is radioactively contaminated, the gas is ionized by the radiation emitted from the contaminated site, and the generated ions are directed toward the two-dimensional ionization current measuring device 39, and this two-dimensional The ionization current measuring device 39 measures a two-dimensional distribution of current values.
[0042]
Here, the data processing device 9 uses the correspondence relationship between the position of each part of the subject obtained in advance and the two-dimensional position of the two-dimensional ionization current measuring device 39 to determine the subject from the two-dimensional distribution of the measured current values. Obtain the contamination radioactivity distribution of each part. In this way, the two-dimensional distribution of the contamination status of the subject can be measured with high accuracy.
[0043]
As a result, the current in the portion of the subject divided into two dimensions can be accurately measured. Therefore, the radioactivity of each part of the subject can be accurately measured.
[0044]
Next, a radiation measuring apparatus according to a tenth embodiment of the present invention is shown in FIGS. That is, according to this embodiment, as shown in FIG. 10B, at least two or more gas suction ports 29 installed in the vicinity of the measurement position, the pipe 4 connecting them, and the ionization from each pipe 4 Corresponding to a switching means 40 such as an electromagnetic valve for switching the gas sent to the current measuring device 8, a data processing device 9 for calculating the radiation dose from the ionization current measurement value of each gas suction port 29, and the gas suction port 29. Display device 30 for displaying the radiation measurement result, and electrode section 13 in which strip-type anode electrodes 11 and cathode electrodes 12 are alternately arranged on insulating substrate 10 as shown in FIG. An electrode portion in which electrodes are arranged in the order of strip-type anode electrode 11, guard electrode 15, cathode electrode 12, guard electrode 15, anode electrode 11, guard electrode 15. Etc. consisting of the ionization current measuring device 8 was used.
[0045]
In this configuration, the switching means 40 sequentially switches the connection of the gas suction ports 29, and the ionization current measuring device 8 measures the ionization current while sucking the gas near each suction port with the suction device 3. The radiation intensity in the vicinity of each suction port is obtained by using a conversion constant for the radiation intensity from the measured current value and the current value obtained in advance. If such measurement is performed, the radiation intensity at the location to be measured can be measured efficiently and accurately.
[0046]
Next, a radiation measuring apparatus according to an eleventh embodiment of the present invention is shown in FIGS. That is, as shown in FIG. 11B, the measurement chamber 2 having an open surface 2a facing the surface of the measurement object 1, and the anode electrode 11 attached to the inner surface of the measurement chamber 2 as shown in FIG. Electrode portions 13 having alternating electrodes and cathode electrodes 12 arranged thereon, voltage applying means 14 for applying a voltage to the electrode portions 13, current measuring means 7 for measuring ions collected by the electrodes as an ionization current, and measured current It comprises a data processing device 9 for calculating the radiation dose from the value.
[0047]
When the opening 2a of the measurement chamber 2 is brought close to or in close contact with the surface of the measurement object 1, the space 2d in the measurement chamber 2 is blocked by the surface of the measurement object 1. Ions generated by ionization of radiation emitted from the surface radionuclide stay in the space with a certain lifetime. For example, in the case of α rays, the space 2d has a range in the air of about 5 cm. Therefore, when the thickness of the space 2d in the measurement chamber 2 is set to about 5 cm, the space 2d is generated in the vicinity of the electrode portion 13. Ions are present. The ions are efficiently collected by the electrode unit 13, the current is measured by the current measuring unit 12, and the radiation is measured from the current measured by the data processing device 9 using a conversion constant.
In this way, radioactivity can be accurately measured with a simple apparatus configuration.
[0048]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain a radiation measuring apparatus capable of measuring radioactivity simply and accurately with high efficiency.
[Brief description of the drawings]
1A and 1B are diagrams showing a configuration of a radioactivity measuring apparatus according to a first embodiment of the present invention, in which FIG. 1A is a detailed view of an electrode portion, and FIG.
FIGS. 2A and 2B are diagrams showing a configuration of a radioactivity measuring apparatus according to a second embodiment of the present invention, in which FIG. 2A is a detailed view of an electrode portion, and FIG.
FIG. 3 is an overall perspective view showing a configuration of a radioactivity measuring apparatus according to a third embodiment of the present invention.
FIG. 4 is an overall perspective view showing a configuration of a radioactivity measuring apparatus according to a fourth embodiment of the present invention.
FIGS. 5A and 5B are diagrams showing a configuration of a radioactivity measuring apparatus according to a fifth embodiment of the present invention, where FIG. 5A is a detailed view of an electrode portion, and FIG.
6A and 6B are diagrams showing a configuration of a radioactivity measuring apparatus according to a sixth embodiment of the present invention, where FIG. 6A is a detailed view of an electrode portion, and FIG. 6B is an overall perspective view.
FIG. 7 is a front view showing a configuration of a radioactivity measuring apparatus according to a seventh embodiment of the present invention.
FIG. 8 is a front view showing a configuration of a radioactivity measuring apparatus according to an eighth embodiment of the present invention.
FIGS. 9A and 9B are diagrams showing a configuration of a radioactivity measuring apparatus according to a ninth embodiment of the present invention, where FIG. 9A is a detailed view of an electrode portion, and FIG. 9B is a front view;
10A and 10B are diagrams showing a configuration of a radioactivity measuring apparatus according to a tenth embodiment of the present invention, where FIG. 10A is a detailed view of an electrode portion, and FIG. 10B is a front view.
11A and 11B are diagrams showing a configuration of a radioactivity measuring apparatus according to an eleventh embodiment of the present invention, where FIG. 11A is a detailed view of an electrode portion, and FIG. 11B is a front view.
FIG. 12 is a schematic configuration diagram showing a conventional radiation measuring apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Measurement object, 2 ... Measurement chamber, 3 ... Suction machine, 4 ... Pipe, 5 ... Filter, 6 ... Ion collection means, 7 ... Current measurement means, 8 ... Ionization current measurement apparatus, 9 ... Data processing apparatus, 10 DESCRIPTION OF SYMBOLS ... Board | substrate, 11 ... Anode electrode, 12 ... Cathode electrode, 13 ... Electrode part, 14 ... Voltage supply means, 15 ... Guard electrode, 16 ... Electrode, 17 ... Gas through-hole, 18 ... Signal collection electrode, 19 ... Guard electrode, DESCRIPTION OF SYMBOLS 20 ... Ground electrode, 21 ... Electrode plate, 22 ... Insulating material, 23 ... Gas converging means, 24 ... Air blower, 25 ... Gas diffusion means, 26 ... Gas suction port, 27 ... Gas suction port for right hand 28 ... Gas suction for left hand Mouth, 29 ... Shoe sole gas suction port, 30 ... Display device, 31 ... Exhaust port, 32 ... Right hand ionization current measurement device, 33 ... Left hand ionization current measurement device, 34 ... Shoe bottom ionization current measurement device, 35 ... many gas suction ports, 36 ... gas compression means, 37 ... back strip, 38 ... dielectric plate, 39 ... two-dimensional ionization current measuring device, 40 ... switching means.

Claims

A measurement chamber for storing a measurement object to be measured for radiation; a suction device for sucking a gas in the measurement chamber and recirculating the gas into the measurement chamber; and a recirculation path for the gas, An ionization current measuring device comprising an electrode part for collecting gaseous ions sucked from the vicinity and a current measuring means for measuring the ionization current of the collected ions, and calculating a radiation dose from a measurement value by the ionizing current measuring device In a radiation measurement device comprising a data processing device for processing,
The electrode section is composed of three electrode plates, each of which includes a signal collecting electrode plate, a guard electrode plate, and a ground electrode plate. Each electrode plate has a plurality of electrodes on an insulating substrate having a gas permeable hole. A radiation measuring apparatus, wherein each of the electrode plates is arranged such that a substrate surface is perpendicular to a gas path.

The signal collecting electrode plates, radiation measurement device according to claim 1, characterized in that arranged two or more pairs of electrode plates and the ground electrode plate guard.

Gas converging means for converging the gas in the measurement chamber to the recirculation path, a blower for accelerating the speed of the gas recirculated in the measurement chamber, and gas diffusion means for diffusing the accelerated gas into the measurement chamber And the radiation measuring apparatus according to claim 1 or 2 .