JP5450356B2 - Radiation detection method - Google Patents

Radiation detection method Download PDF

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JP5450356B2
JP5450356B2 JP2010253371A JP2010253371A JP5450356B2 JP 5450356 B2 JP5450356 B2 JP 5450356B2 JP 2010253371 A JP2010253371 A JP 2010253371A JP 2010253371 A JP2010253371 A JP 2010253371A JP 5450356 B2 JP5450356 B2 JP 5450356B2
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JP2012103179A (en
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孝広 田所
博司 北口
克宜 上野
明久 海原
均 桑原
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Hitachi Ltd
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本発明は、原子力発電所において使用される放射線検出器及び検出方法に係り、特に、高いバックグラウンドの環境で、多核種分析に好適な放射線検出装置及びその方法に関する。   The present invention relates to a radiation detector and detection method used in a nuclear power plant, and more particularly to a radiation detection apparatus and method suitable for multi-nuclide analysis in a high background environment.

従来、原子力発電所における炉水内放射性核種の分析では、炉水をポリ容器等にサンプリングした後、１日程度放置し、短半減期核種（窒素１３，酸素１９等）を減衰させた後、ゲルマニウム半導体検出器を用いて分析していた。   Conventionally, in the analysis of radionuclides in reactor water at nuclear power plants, the reactor water is sampled in a plastic container or the like and then left for about one day to attenuate short half-life nuclides (nitrogen 13, oxygen 19 and the like) The analysis was performed using a germanium semiconductor detector.

炉水内放射性核種分析の省力化及び低被曝化のため、オンライン化が望まれているが、炉水中の主放射性核種である窒素１３，酸素１９の強度が強いため、炉水中の微量放射性核種であるコバルト５８及び６０，マンガン５４及び５６，よう素１３１，１３３，セシウム１３４，１３７等を、オンラインで精度良く測定するのが困難だった。   To save labor and reduce exposure to radionuclide analysis in reactor water, it is desired to make it online. However, since the strength of nitrogen 13 and oxygen 19, which are the main radionuclides in reactor water, is strong, trace amounts of radionuclides in reactor water It was difficult to accurately measure cobalt 58 and 60, manganese 54 and 56, iodine 131, 133, cesium 134, 137 and the like on-line.

原子力発電所において、オンラインの放射性核種モニタとしては、〔特許文献１〕に記載のような、ゲルマニウム半導体検出器を適用した高感度オフガスモニタが製品化されており、バックグランドとなっている窒素１３の抑制には、１８０°方向に設置した２台の検出器を用いたアンチ同時計数法が採用されている。又、〔特許文献２〕に記載のような、１台の検出器の周囲を他の検出器で囲んだコンプトン抑制法等が適用されている。   In a nuclear power plant, as an on-line radionuclide monitor, a highly sensitive off-gas monitor using a germanium semiconductor detector as described in [Patent Document 1] has been commercialized, and nitrogen 13 as a background In order to suppress this, an anti coincidence method using two detectors installed in a 180 ° direction is employed. Moreover, the Compton suppression method etc. which surrounded the circumference | surroundings of one detector by another detector like [patent document 2] are applied.

しかし、これらの方法では、窒素１３の抑制は可能であるが、他の核種を精度良く測定することはできない。また、高感度オフガスモニタは、エネルギーの低いガンマ線放出核種を測定対象としているため、低いエネルギーのガンマ線の測定感度が相対的に高くなるように薄い板状のゲルマニウム半導体検出器を適用しているが、高いエネルギーのガンマ線の測定も必要な炉水中の放射性核種分析には適用できない。   However, these methods can suppress nitrogen 13 but cannot accurately measure other nuclides. The high-sensitivity off-gas monitor uses gamma-ray emitting nuclides with low energy, so a thin plate-shaped germanium semiconductor detector is applied so that the measurement sensitivity of low-energy gamma rays is relatively high. However, high-energy gamma-ray measurements cannot be applied to the analysis of radionuclides in reactor water.

原子力発電所における放射線のオンラインモニタとしては、ＮａＩシンチレーション検出器を用いた各種漏えい放射線検知モニタが使用されているが、エネルギー分解能が不十分なために、精度良い核種分析が困難である。また、シリコン半導体検出器を用いたエリアモニタ，イオンチェンバーを用いた主蒸気線量モニタ等が使用されているが、いずれも、核種分析が困難であることから、オンラインでの炉水中核種を分析することは困難である。   As an on-line monitor of radiation at a nuclear power plant, various leaked radiation detection monitors using a NaI scintillation detector are used. However, since the energy resolution is insufficient, accurate nuclide analysis is difficult. In addition, an area monitor using a silicon semiconductor detector, a main vapor dose monitor using an ion chamber, etc. are used. However, since it is difficult to analyze nuclides, online analysis of nuclides in reactor water is performed. It is difficult.

特開２００１−２３５５４６号公報JP 2001-235546 A 特開平１１−１９４１７０号公報Japanese Patent Laid-Open No. 11-194170

本発明の目的は、原子力発電所において使用され、高いバックグラウンドの環境で、多核種分析に好適な放射線検出装置及びその方法を提供することである。   An object of the present invention is to provide a radiation detection apparatus and method suitable for multi-nuclide analysis used in a nuclear power plant and in a high background environment.

上記の目的を達成するための本発明は、複数（３台以上）の核種分析可能な放射線検出器を用い、複数の放射線検出器のうち、対向位置に設置した検出器組と非対向位置に設置した検出器組で放射線検出装置を構成し、各放射線検出器によりガンマ線の測定時刻と波高値を測定し、対向位置に設置した検出器組及び非対向位置に設置した検出器組で、それぞれ同時計数及び非同時計数の判定を行い、同時計数及び非同時計数判定の情報と、波高値情報から求めるガンマ線エネルギー情報をもとに、放射性核種分析を行う。   In order to achieve the above object, the present invention uses a plurality (three or more) of radiation detectors capable of analyzing nuclides, and among the plurality of radiation detectors, a detector set installed at an opposed position and a non-opposed position. Configure the radiation detection device with the installed detector set, measure the gamma ray measurement time and peak value with each radiation detector, with the detector set installed at the opposed position and the detector set installed at the non-opposed position, Judgment of coincidence counting and non-coincidence counting is performed, and radionuclide analysis is performed based on information on coincidence counting and non-simultaneous counting determination and gamma ray energy information obtained from peak value information.

本発明によれば、原子力発電所において、高バックグラウンド下で多核種分析に好適な放射線検出装置及びその方法を提供できる。   ADVANTAGE OF THE INVENTION According to this invention, the radiation detection apparatus suitable for a multi-nuclide analysis and its method can be provided in a nuclear power plant under a high background.

本発明の実施例１の放射線検出装置の構成図である。It is a block diagram of the radiation detection apparatus of Example 1 of this invention. 実施例１の放射線検出装置における同時計数，非同時計数判定の一例である。2 is an example of coincidence counting and non-coincidence determination in the radiation detection apparatus according to the first embodiment. 実施例１の放射線検出装置における同時計数，非同時計数判定の一例である。2 is an example of coincidence counting and non-coincidence determination in the radiation detection apparatus according to the first embodiment. 実施例１の対向方向に設置した検出器の波高値スペクトルの一例である。2 is an example of a peak value spectrum of a detector installed in the facing direction of Example 1. FIG. 実施例２の非対向方向に設置した検出器の波高値スペクトルの一例である。It is an example of the peak value spectrum of the detector installed in the non-facing direction of Example 2. 実施例３の放射線検出装置の構成図である。It is a block diagram of the radiation detection apparatus of Example 3. 実施例４の放射線検出装置の構成図である。It is a block diagram of the radiation detection apparatus of Example 4.

以下に説明する各実施例では、ゲルマニウム半導体検出器、またはＬａＢｒ3（Ｃｅ）シンチレーション検出器等である放射線検出器を３台以上用い、放射線検出装置を検出対象物の周囲の対向位置に設置した検出器組と、非対向位置に設置した検出器組で構成し、各放射線検出器のガンマ線の測定時刻と波高値を測定することで、対向位置に設置した検出器組及び非対向位置に設置した検出器組で、それぞれ同時計数及び非同時計数を行う。 In each of the embodiments described below, three or more radiation detectors such as a germanium semiconductor detector or a LaBr 3 (Ce) scintillation detector are used, and the radiation detection device is installed at an opposing position around the detection target. It consists of a detector set and a detector set installed at a non-opposing position. By measuring the gamma ray measurement time and peak value of each radiation detector, the detector set installed at the opposing position and the non-opposing position. The coincidence counting and the non-coincidence counting are respectively performed by the detected detector sets.

後述するように、前置増幅器からの出力信号を２つに分岐し、分岐した一つの信号を増幅器を通して波高値測定を行い、分岐した他の一つの信号を波高弁別器を通して時刻情報を含むパルス信号に変換し、パルス信号の立ち上がり時刻を用いて時刻測定を行う。   As will be described later, the output signal from the preamplifier is branched into two, the peak value of the branched signal is measured through the amplifier, and the other one of the branched signals is subjected to a pulse discriminator to include the time information. The signal is converted into a signal, and the time is measured using the rise time of the pulse signal.

シンチレーション検出器を用いる場合は、前置増幅器を用いず、シンチレーション素子の後段に設置した光電子増倍管の出力信号を用いても良い。予め決定しておいた時刻範囲以内に、複数の放射線検出器でガンマ線を検出した場合は、同時計数したと判定し、それ以外の場合は、非同時計数したと判定する。予め決定しておく時刻範囲の幅を、各検出器の計数率、又は出力信号の時間幅に応じて可変にすることで、適切な時刻幅を設定できる。同時計数、及び非同時計数の判定は、データ収集用パソコンに取り込む前にハード的に行っても良いし、パソコンに各放射線検出器の波高値データと検出時刻データを取り込んだ後で、ソフト的に行っても良い。   When a scintillation detector is used, an output signal of a photomultiplier tube installed at a subsequent stage of the scintillation element may be used without using a preamplifier. When gamma rays are detected by a plurality of radiation detectors within a predetermined time range, it is determined that simultaneous counting is performed, and in other cases, it is determined that non-simultaneous counting is performed. An appropriate time width can be set by making the width of the predetermined time range variable according to the count rate of each detector or the time width of the output signal. Judgment of coincidence counting and non-simultaneous counting may be performed by hardware before importing into the data collection personal computer, or after capturing the crest value data and detection time data of each radiation detector into the personal computer. You may go to

炉水中の核種分析は、各放射線検出器で検出した波高値データで求まるガンマ線エネルギーと、複数の放射線検出器の測定時刻データで判定される。この判定は、複数の放射線検出器間の同時計数、または非同時計数の測定結果を用いて行う。   The nuclide analysis in the reactor water is determined by the gamma ray energy obtained from the peak value data detected by each radiation detector and the measurement time data of a plurality of radiation detectors. This determination is performed by using a measurement result of simultaneous counting or non-simultaneous counting among a plurality of radiation detectors.

ガンマ線を放出する放射性の核種は、β+崩壊してほぼ１８０°方向に同時に２本の５１１ｋｅＶのエネルギーのガンマ線を放出する第１の核種群（窒素１３等）、ほぼ同時にエネルギーの異なる２本以上のガンマ線を放出する第２の核種群（コバルト６０等）、ほぼ同時に２本以上のガンマ線を放出しない第３の核種群（マンガン５４，セシウム１３７等）、第１の核種群と第３の核種群の複数の核種群に含まれる核種群（コバルト５８）、及び第２の核種群と第３の核種群の複数の核種群に含まれる核種群（酸素１９，マンガン５６，よう素１３１，よう素１３３，セシウム１３４等）に分類できる。ここで、第２の核種群（コバルト６０等）は、カスケードガンマ線を４π方向に放出する。 The radioactive nuclides that emit gamma rays are the first nuclide group (nitrogen 13 or the like) that emits gamma rays with energy of 511 keV at the same time in the direction of β + decay and almost 180 °, two or more of them having different energies almost simultaneously. The second nuclide group that emits gamma rays (cobalt 60, etc.), the third nuclide group that does not emit two or more gamma rays (manganese 54, cesium 137, etc.), the first nuclide group and the third nuclide almost simultaneously Nuclide group (cobalt 58) included in the plurality of nuclide groups of the group, and nuclide group (oxygen 19, manganese 56, iodine 131, etc.) included in the plurality of nuclide groups of the second nuclide group and the third nuclide group. Elementary 133, cesium 134, etc.). Here, the second nuclide group (such as cobalt 60) emits cascade gamma rays in the 4π direction.

対向位置に設置した検出器組に入射するガンマ線を同時計数することで、第１の核種群の核種（窒素１３等）を選択的に測定することができる。   By simultaneously counting the gamma rays incident on the detector set installed at the opposite position, the nuclides of the first nuclide group (such as nitrogen 13) can be selectively measured.

第２の核種群は、エネルギーの異なるガンマ線を確率的に等方に放出する。したがって、非対向位置に設置した検出器組の同時計数すること、及び同時計数したガンマ線のエネルギーを用いることで、第２の核種群の核種（コバルト６０等）を選択的に測定できる。   The second nuclide group probabilistically emits gamma rays with different energies. Therefore, the nuclide (such as cobalt 60) of the second nuclide group can be selectively measured by simultaneously counting the detector sets installed at the non-opposing positions and using the energy of the gamma rays counted simultaneously.

第３の核種群は、同時に放出するガンマ線が無いことから、対向位置または非対向位置に設置した検出器組に入射するガンマ線を非同時計数すること、及び非同時計数したガンマ線のエネルギーを用いて、第３の核種群の核種（マンガン５４，セシウム１３７等）を選択的に測定することでき、精度良い多核種分析が可能となる。   Since the third nuclide group has no gamma rays that are emitted at the same time, the gamma rays incident on the detector set installed at the opposite position or the non-opposing position are non-simultaneously counted and the energy of the non-simultaneously counted gamma rays is used. The nuclide of the third nuclide group (manganese 54, cesium 137, etc.) can be selectively measured, and accurate multi-nuclide analysis is possible.

非対向位置に設置した検出器組に入射するガンマ線を非同時計数すること、対向位置に設置した検出器組に入射するガンマ線を同時計数することの両方を用い、それぞれの場合のガンマ線エネルギーを用いることで、第１の核種群と第３の核種群の複数の核種群に含まれる核種（コバルト５８等）を精度良く分析でき、β+崩壊してほぼ１８０°方向に同時に２本の５１１ｋｅＶのエネルギーのガンマ線を放出する核種中の寄与が評価可能となる。対向位置及び非対向位置に設置した検出器組に入射するガンマ線を同時計数すること、対向位置及び非対向位置に設置した検出器組に入射するガンマ線を非同時計数することの両方を用いること、それぞれの場合におけるガンマ線エネルギーを用いることで、２の核種群と第３の核種群の複数の核種群に含まれる核種群（酸素１９，マンガン５６，よう素１３１，よう素１３３，セシウム１３４等）を精度良く分析できる。 Both non-simultaneous counting of gamma rays incident on the detector set installed at the non-facing position and simultaneous counting of gamma rays incident on the detector set installed at the opposing position are used, and the gamma ray energy in each case is used. Therefore, it is possible to accurately analyze nuclides (cobalt 58, etc.) contained in a plurality of nuclide groups of the first nuclide group and the third nuclide group, β + decays, and two 511 keV at the same time in approximately 180 ° direction. The contribution in nuclides that emit gamma rays of energy can be evaluated. Using both simultaneous counting of gamma rays incident on the detector set installed at the opposing position and non-opposing position, and non-simultaneous counting of gamma rays incident on the detector set installed at the opposing position and non-opposing position; By using the gamma ray energy in each case, the nuclide groups (oxygen 19, manganese 56, iodine 131, iodine 133, cesium 134, etc.) included in the plurality of nuclide groups of the second nuclide group and the third nuclide group Can be analyzed with high accuracy.

以下、本発明の各実施例を、図面を参照して説明する。   Embodiments of the present invention will be described below with reference to the drawings.

本発明の実施例１の放射線検出装置の構成を、図１に基づいて説明する。本実施例の放射線検出装置は、図１に示すように、検出対象物１の周囲に複数台（３台以上）設置したガンマ線を検出する放射線検出器２、各放射線検出器２からの信号を増幅するための前置増幅器３、前置増幅器３からの信号の増幅と波形を整形する増幅器４、前置増幅器３からの信号を時刻情報を含むパルス信号（時刻信号）に変換する波高弁別器５、増幅器４により波形整形されたパルスの波高値及び時刻信号から、波高値及び検出時刻を測定する波高値及び検出時刻の測定器６、測定器６に接続されたデータ収集用パソコン７を備えている。   The configuration of the radiation detection apparatus according to the first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the radiation detection apparatus according to the present embodiment includes a plurality of (three or more) gamma ray detectors installed around the detection target 1, and a signal from each radiation detector 2. Preamplifier 3 for amplification, amplifier 4 for amplification and shaping of signal from preamplifier 3, and pulse height discriminator for converting signal from preamplifier 3 into a pulse signal (time signal) including time information 5. A crest value and detection time measuring device 6 for measuring a crest value and a detection time from a crest value and a time signal of a pulse shaped by the amplifier 4, and a data collection personal computer 7 connected to the measuring device 6. ing.

複数の放射線検出器２は、検出対象物１の周囲に、対向位置に設置した検出器組と非対向位置に設置した検出器組で構成され、測定器６により各放射線検出器２が波高値及び検出時刻の測定器６によりガンマ線の測定時刻と波高値を測定する。   The plurality of radiation detectors 2 are composed of a detector group installed at an opposing position and a detector group installed at a non-opposing position around the detection target 1, and each radiation detector 2 is subjected to a peak value by the measuring device 6. Then, the gamma ray measurement time and peak value are measured by the detection time measuring device 6.

図２に、放射線検出装置における同時計数及び非同時計数判定の一例を示す。予め決定しておいた同時計数時刻範囲以内に、複数の放射線検出器２でガンマ線を検出した場合は同時計数したと判定し、それ以外の場合は、非同時計数したと判定する。同時計数、及び非同時計数の判定は、前述したように、データ収集用パソコン７に取り込む前にハード的に行っても良いし、データ収集用パソコン７に各放射線検出器２の波高値データと検出時刻データをリストデータとして取り込んだ後で、ソフト的に行っても良い。   FIG. 2 shows an example of coincidence counting and non-coincidence determination in the radiation detection apparatus. If gamma rays are detected by a plurality of radiation detectors 2 within the predetermined coincidence time range, it is determined that simultaneous counting is performed, and otherwise, it is determined that non-simultaneous counting is performed. As described above, the simultaneous counting and the non-simultaneous counting may be determined by hardware before being taken into the data collection personal computer 7, or the peak value data of each radiation detector 2 may be stored in the data collection personal computer 7. After the detection time data is taken in as list data, it may be performed in software.

図２に示す例では、検出器１の波高値１と検出器３の波高値３が小さく、検出器１の時刻信号１と検出器３の時刻信号３が予め決定しておいた同時計数時刻範囲内にあり、同時係数であることを示している。検出器２の波高値２は大きく、検出器２の時刻信号２は、予め決定しておいた同時計数時刻範囲内になく、非同時係数であることを示している。   In the example shown in FIG. 2, the peak value 1 of the detector 1 and the peak value 3 of the detector 3 are small, and the time signal 1 of the detector 1 and the time signal 3 of the detector 3 are determined in advance. It is within the range, indicating that it is a simultaneous coefficient. The peak value 2 of the detector 2 is large, indicating that the time signal 2 of the detector 2 is not within the predetermined coincidence time range and is a non-simultaneous coefficient.

図３に、放射線検出器を対向位置に設置した場合の波高値スペクトルの一例を示す。横軸に波高値を、縦軸に計数率をとって波高値スペクトルを示している。   FIG. 3 shows an example of a peak value spectrum when the radiation detector is installed at the opposite position. The peak value spectrum is shown with the peak value on the horizontal axis and the count rate on the vertical axis.

この例では、非同時計数と同時計数の両方を合わせた波高値スペクトルに対して、同時計数における波高値スペクトルは、β+崩壊で生成する５１１ｋｅＶのエネルギーのガンマ線を選択的に測定しているので、前述した第１の核種群（窒素１３等）を精度良く測定可能である。 In this example, the crest value spectrum in both coincidence counting and coincidence counting selectively measures the gamma ray of energy of 511 keV generated by β + decay. The first nuclide group (nitrogen 13 or the like) described above can be measured with high accuracy.

図４に、放射線検出器を非対向位置に設置した場合の波高値スペクトルの一例を示す。この例では、非同時計数と同時計数の両方を合わせた波高値スペクトルに対して、同時計数における波高値スペクトルは、ほぼ同時にエネルギーの異なる２本以上のガンマ線を放出する前述の第２の核種群（コバルト６０等）からのガンマ線を選択的に測定でき、第２の核種群（コバルト６０等）を精度良く測定可能である。   FIG. 4 shows an example of a peak value spectrum when the radiation detector is installed at a non-opposing position. In this example, the crest value spectrum obtained by combining both the non-coincidence count and the coincidence count is equivalent to the crest value spectrum in the coincidence count that emits two or more gamma rays having different energies at the same time. Gamma rays from (cobalt 60, etc.) can be selectively measured, and the second nuclide group (cobalt 60, etc.) can be measured with high accuracy.

また、前述の第３の核種群は、同時に放出するガンマ線が無いことから、対向位置または非対向位置に設置した検出器組に入射するガンマ線を非同時計数すること、及び非同時計数したガンマ線のエネルギーを用いて、第３の核種群の核種（マンガン５４，セシウム１３７等）を選択的に測定することでき、精度良い多核種分析が可能となる。   In addition, since the third nuclide group described above does not have gamma rays that are emitted simultaneously, the gamma rays incident on the detector set installed at the facing position or the non-facing position are non-simultaneously counted. By using energy, the nuclides of the third nuclide group (manganese 54, cesium 137, etc.) can be selectively measured, and accurate multi-nuclide analysis is possible.

このように、第１の核種群（窒素１３等），第２の核種群（コバルト６０等），第３の核種群の核種（マンガン５４，セシウム１３７等）を選択的に測定できるので、対向位置に設置した検出器組に入射するガンマ線を非同時計数すること、対向位置に設置した検出器組に入射するガンマ線を同時計数することの両方を用い、それぞれの場合のガンマ線エネルギーを用いることで、第１の核種群と第３の核種群の複数の核種群に含まれる核種（コバルト５８等）を精度良く分析でき、β+崩壊してほぼ１８０°方向に同時に２本の５１１ｋｅＶのエネルギーのガンマ線を放出する核種中の寄与が評価可能となる。対向位置及び非対向位置に設置した検出器組に入射するガンマ線を同時計数すること、対向位置及び非対向位置に設置した検出器組に入射するガンマ線を非同時計数することの両方を用いること、それぞれの場合におけるガンマ線エネルギーを用いることで、２の核種群と第３の核種群の複数の核種群に含まれる核種群（酸素１９，マンガン５６，よう素１３１，よう素１３３，セシウム１３４等）を精度良く分析できる。 In this way, the first nuclide group (nitrogen 13 etc.), the second nuclide group (cobalt 60 etc.), and the third nuclide group nuclide (manganese 54, cesium 137 etc.) can be selectively measured. By using non-simultaneous counting of gamma rays incident on the detector set installed at the position and simultaneously counting gamma rays incident on the detector set installed at the opposite position, using the gamma ray energy in each case , Can accurately analyze nuclides (cobalt 58, etc.) contained in a plurality of nuclide groups of the first nuclide group and the third nuclide group, β + decays, and simultaneously has two 511 keV energies in approximately 180 ° direction. The contribution in nuclides that emit gamma rays can be evaluated. Using both simultaneous counting of gamma rays incident on the detector set installed at the opposing position and non-opposing position, and non-simultaneous counting of gamma rays incident on the detector set installed at the opposing position and non-opposing position; By using the gamma ray energy in each case, the nuclide groups (oxygen 19, manganese 56, iodine 131, iodine 133, cesium 134, etc.) included in the plurality of nuclide groups of the second nuclide group and the third nuclide group Can be analyzed with high accuracy.

本発明の実施例２の放射線検出装置の構成を、図５に基づいて説明する。本実施例の実施例１と同様に、検出対象物１の周囲に、対向位置に設置した検出器組と非対向位置に設置した検出器組で構成され、測定器により各放射線検出器２が波高値及び検出時刻の測定器によりガンマ線の測定時刻と波高値を測定する。   The configuration of the radiation detection apparatus according to the second embodiment of the present invention will be described with reference to FIG. As in the first embodiment of the present embodiment, the detection target 1 is composed of a detector set installed at an opposing position and a detector set installed at a non-opposing position, and each radiation detector 2 is measured by a measuring instrument. The measurement time and peak value of gamma rays are measured with a measuring device for peak value and detection time.

実施例２では、放射線検出器２を検出対象物１の中心から等距離に設置する。同じ検出効率の複数台の放射線検出器２を用い、検出対象物１の中心から等距離に設置することで、検出対象物１中の核種の濃度が計数率の補正をすることなく測定可能となる。   In the second embodiment, the radiation detector 2 is installed at an equal distance from the center of the detection target 1. By using a plurality of radiation detectors 2 having the same detection efficiency and being installed at an equal distance from the center of the detection target 1, the concentration of the nuclide in the detection target 1 can be measured without correcting the count rate. Become.

本発明の実施例３の放射線検出装置の構成を、図６に基づいて説明する。実施例３は、実施例２と同様に構成しており、検出対象物１の体積を大きくなるように径の大きい円筒で形成している。   The configuration of the radiation detection apparatus according to the third embodiment of the present invention will be described with reference to FIG. The third embodiment is configured in the same manner as the second embodiment, and is formed of a cylinder having a large diameter so that the volume of the detection object 1 is increased.

検出対象物１の体積が少ない場合、検出対象の核種の絶対数が少ないことから、各検出器の計数率が低くなり測定時間が長くなる。検出対象物１の体積を大きくすることで、各検出器の計数率が高くなり測定時間を短くできる。また、同じ測定時間においては、検出対象物中の核種の濃度のより精度良い測定が可能となる。   When the volume of the detection object 1 is small, the absolute number of detection target nuclides is small, so that the counting rate of each detector is low and the measurement time is long. By increasing the volume of the detection object 1, the counting rate of each detector increases and the measurement time can be shortened. In addition, it is possible to measure the concentration of the nuclide in the detection target with higher accuracy during the same measurement time.

本発明の実施例４の放射線検出装置の構成を、図７に基づいて説明する。実施例４は、実施例１と同様に構成している。   The configuration of the radiation detection apparatus according to the fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment is configured in the same manner as the first embodiment.

実施例４では、検出対象物１が流れている配管から、配管を分岐し、分岐した配管の分岐口８から測定位置９までの時間差を設けることで、検出したい核種に対して、短半減期核種がバックグラウンドとなっている場合は、そのバックグラウンドを低減できる。また、検出位置を雰囲気のバックグラウンドが低い場所に設定することで、精度良い測定が可能となる。   In Example 4, the pipe is branched from the pipe through which the detection target 1 flows, and a short half-life is obtained for the nuclide to be detected by providing a time difference from the branch port 8 of the branched pipe to the measurement position 9. When the nuclide is in the background, the background can be reduced. In addition, by setting the detection position to a place where the background of the atmosphere is low, accurate measurement can be performed.

１ 検出対象物
２ 放射線検出器
３ 前置増幅器
４ 増幅器
５ 波高弁別器
６ 測定器
７ データ収集用パソコン
８ 配管の分岐口
９ 検出位置 DESCRIPTION OF SYMBOLS 1 Detection target 2 Radiation detector 3 Preamplifier 4 Amplifier 5 Wave height discriminator 6 Measuring device 7 Data collection personal computer 8 Piping branch 9 Detection position

Claims (2)

ガンマ線放出核種を、β + 崩壊をしてほぼ１８０°方向に５１１ｋｅＶのエネルギーのガンマ線を放出する第１の核種群、カスケードガンマ線を４π方向に放出する第２の核種群、第１の核種群及び第２の核種群のいずれでもない第３の核種群、第１の核種群及び第２の核種群に含まれる核種、第２の核種群及び第３の核種群に含まれる核種に分類し、放射線が入射する入射部を有する検出器を検出器組として、入射部を互いに対向する位置に設置した検出器組でガンマ線を同時刻に計数したガンマ線の波高値情報、入射部を互いに対向する位置に設置した検出器組で同時刻に計数しなかった測定対象物のガンマ線の波高値情報、入射部を互いに非対向となる位置に設置した検出器組で同時刻に計数した測定対象物のガンマ線の波高値情報、及び、入射部を互いに非対向となる位置に設置した検出器組で同時刻に計数しなかった測定対象物のガンマ線の波高値情報を用いて、前記分類した核種を同定することを特徴とする放射線検出方法。
 A first nuclide group that emits gamma rays with energy of 511 keV in a direction of approximately 180 ° by β + decay, a second nuclide group that emits cascade gamma rays in the 4π direction, a first nuclide group, Classify into a nuclide group that is not one of the second nuclide group, a nuclide group that is included in the first nuclide group and the second nuclide group, a nuclide group that is included in the second nuclide group, and the third nuclide group ; as the detector sets of detectors having an incident portion which radiation is incident, peak value information of gamma rays gamma rays was counted at the same time at the installation the detector set at a position opposite the entrance portion to each other, facing each other incident portion position Gamma ray peak value information of the measurement object that was not counted at the same time by the detector set installed in, and the gamma ray of the measurement object counted at the same time by the detector set installed at positions where the incident parts are not facing each other Wave height information, and , Radiation, characterized in that by using the peak value information of the gamma ray of the measuring object that did not count at the same time at the installation the detector set at a position which is a non-facing the entrance portion to each other, to identify the species that the classification Detection method.
前記第１の核種群に含まれる核種として窒素１３を、第２の核種群に含まれる核種としてコバルト６０を、第３の核種群に含まれる核種としてマンガン５４，セシウム１３７を、前記第１の核種群と第３の核種群の複数の核種群に含まれる核種としてコバルト５８を、前記第２の核種群と第３の核種群の複数の核種群に含まれる核種として酸素１９，マンガン５６，よう素１３１，よう素１３３，セシウム１３４を測定対象とすることを特徴とする請求項１に記載の放射線検出方法。 Nitrogen 13 as the nuclide included in the first nuclide group, cobalt 60 as the nuclide included in the second nuclide group, manganese 54, cesium 137 as the nuclide included in the third nuclide group, Cobalt 58 is used as a nuclide contained in a plurality of nuclide groups of the nuclide group and the third nuclide group, oxygen 19, manganese 56, as a nuclide contained in a plurality of nuclide groups of the second nuclide group and the third nuclide group. The radiation detection method according to claim 1, wherein iodine 131, iodine 133, and cesium 134 are measured .
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