Development of a GdSiO (GPS) scintillator-based alpha imaging detector for rapid plutonium detection in high-radon environments

Morishita, Yuki; Izaki, Kenji; Kaneko, Junichi*; Yamamoto, Seiichi*; Higuchi, Mikio*; Torii, Tatsuo

IEEE Transactions on Nuclear Science, 67(10), p.2203 - 2208, 2020/10

https://doi.org/10.1109/TNS.2020.3014997

We developed a GdSiO (GPS) scintillator-based alpha imaging detector and demonstrated its effectiveness by evaluating actual Pu particle and Rn progeny. The GPS scintillator plate was prepared by a sintering method. The outer dimensions of the GPS scintillator plate were 5 5 cm, and the scintillator layer was approximately 50 m on a 3-mm-thick high-transparency glass. The plate was optically coupled to a position-sensitive photomultiplier tube with silicone grease. The developed imaging detector exhibited good uniformity. Pu particle activities were accurately evaluated at 14 different positions, and the difference in activity was within 6%. Radon-222 (Rn) progeny counts were reduced by 65.3% by applying an energy window. Although the Pu/Rn progeny activity ratio was 1/51, the Pu particle was successfully identified among Rn progeny within the 5 min-measurement time. The imaging detector has an excellent ability for detecting Pu among Rn progeny. Thus, this detector is useful for alpha contamination monitoring in high-radon-background environments.

Optimization of thickness of GAGG scintillator for detecting an alpha particle emitter in a field of high beta and gamma background

Morishita, Yuki; Yamamoto, Seiichi*; Izaki, Kenji; Kaneko, Junichi*; Hoshi, Katsuya; Torii, Tatsuo

Radiation Measurements, 112, p.1 - 5, 2018/05

https://doi.org/10.1016/j.radmeas.2018.02.003

To detect plutonium isotopes (Pu, Pu, and Pu) in a field of high beta and background, an alpha particle detector with low beta and -ray sensitivity is required. Therefore, we optimized the thickness of the GAGG scintillator for alpha particle detection in a field of high beta and background. We prepared three GAGG scintillators with thicknesses of 0.05 mm, 0.07 mm, and 0.1 mm. Each of the GAGG scintillators was coupled optically to the SiPM array, which was used as the photodetector. Alpha, beta, and rays were irradiated onto the developed alpha particle detector, and their spectra were obtained. All GAGG scintillators used in this study were not sensitive to rays with a dose rate of 1 mSv/h. The beta count of the 0.05-mm-thick GAGG was only 1/100 that of the 0.1-mm-thick GAGG. Therefore, the 0.05-mm-thick GAGG scintillator is promising from the viewpoint of detecting plutonium contamination in a field with high beta and background.

Performance comparison of scintillators for alpha particle detectors

Morishita, Yuki; Yamamoto, Seiichi*; Izaki, Kenji; Kaneko, Junichi*; Toi, Kohei*; Tsubota, Yoichi*; Higuchi, Mikio*

Nuclear Instruments and Methods in Physics Research A, 764, p.383 - 386, 2014/11

https://doi.org/10.1016/j.nima.2014.07.046

Application of imaging plate to the radiation protection in the MOX fuel fabrication facility, 2; The effect of changing exposure conditions and analysis conditions

Sagawa, Naoki; Izaki, Kenji; Mizuniwa, Harumi*

JAEA-Technology 2013-029, 28 Pages, 2013/11

JAEA-Technology-2013-029.pdf:3.35MB

Developed in the Mixed Oxide fuel fabrication facility, Basic handling of IP, analysis method, detection of Pu and radioactivity quantification. These are the conditions that the exposure conditions and the analysis condition are constant. However, in the case of Contamination has occurred in the workplace, contaminated samples are not only Pu. It may contain a Pb or RnTn. Then, if other work is being carried out in a room that is the operation of IP, it's difficult to darken the room. PSL is reduced when light hits the IP. In this study, we have investigated in order to upgrade radiation protection, in the case of Containing the Pb or PSL reduction by light. Additionally, regarding change of analysis condition, the analysis method was examined when the resolution was changed to 50 micro, 100 micro and 200 micro.

Study on pulse height discrimination of alpha-ray using ZnS(Ag) scintillation detector; Adaptability to contamination monitoring equipments

Izaki, Kenji; Ino, Kazuo*; Mizuniwa, Harumi

JAEA-Research 2008-107, 46 Pages, 2009/03

JAEA-Research-2008-107.pdf:3.81MB

The contamination control has been carried out by alpha-ray measurement in facilities where handling plutonium like the MOX fuel manufacturing facility and the reprocessing facility, etc. In the case of alpha-ray measurement, it is necessary to consider the influence of radon progeny that is natural radionuclide. The influence of radon progeny has been decreased by pulse height discrimination technique using the semiconductor detector as needed. However, the semiconductor detector has potentially significant problems such as the durability and noise susceptibility. Therefore the accuracy of pulse height discrimination by the ZnS(Ag) scintillation detector was confirmed as alternative to the semiconductor detector. This report shows the accuracy of pulse height discrimination technique using the ZnS(Ag) scintillation detector and evaluates the adaptability to contamination control equipments.

Investigation concerning influence of cosmic rays on criticality accident alarm system; Relationship between "Single Detection" and cosmic rays

Izaki, Kenji; Suzuki, Hideki; Tsubaki, Hirohiko; Ozeki, Kiyoshi

JAEA-Research 2007-009, 40 Pages, 2007/03

JAEA-Research-2007-009.pdf:4.17MB

Criticality Accident Alarm System (CAAS) has been used in Nuclear Fuel Cycle Engineering Laboratories for about 20 years, and there is occurrence of the abnormal signal called "Single Detection", as an operational problem of CAAS. Radiation Protection Division has investigated the causes affecting "Single Detection", as well as reducing the influence of noises such as electromagnetic waves and power source variations. This report shows the result of the long-term observation with detectors of CAAS and describes that cosmic rays have high possibility to cause "Single Detection".

Development of the Self Moving Survey System

Ishikawa, Hisashi; Nemoto, Norio; Izaki, Kenji; Kobayashi, Hirohide; Tanizawa, Teruaki*; Kanazawa, Yoshito*

JNC TN8400 2004-008, 124 Pages, 2004/05

JNC-TN8400-2004-008.pdf:58.81MB

In order to strengthen the functions of the self moving survey system, the design of the truck and the data transmission system, the investigation of the handling function and the durability test assumed under the disaster environment were executed.As the basic performance of the self moving survey system, it was demanded to have the functions in order to run on the bumpy road, go up and down the stairs and open and shut of the door. And the remote control by the PHS line or the SS wireless is adopted as an operational method. Moreover, as the function that can monitor the disaster situation in the facility, it was assumed the design that make modular the measurement equipments, which mainly measure alpha ray, gamma ray and neutron, and installed it.In consideration of the radiation monitoring under the environment that assumes the critical accident and a fire and the explosion etc. heat test, humidity test, radiation test, and aerosol (smoke) test for monitoring equipments were executed. As a result of the tests, it was confirmed that all equipment except the semiconductor detector operated normally.

Development of dust monitor adopted static electrical collecting system

Ito, Yasuhisa; Noda, Kimio; ; Izaki, Kenji; Ebana, Minoru*

JNC TN8410 2001-007, 81 Pages, 2001/03

JNC-TN8410-2001-007.pdf:3.42MB

Dust Monitor is one of the equipments that measure the concentration of air-borne radioactive materials. This monitor generally collects the dusts in the air by the air pumps, but this system has several problems. Therefore we made the prototypes of Dust Monitor and Dust Sampler that adopted static electrical collecting system, and examined these prototypes. As the result of examination, we confirmed that the static electrical collecting system has the same collection efficiency with air suction system and it is possible to use these prototypes in controlled area.

None

Ebana, Minoru; ; Izaki, Kenji

PNC TN8410 95-273, 188 Pages, 1995/11

PNC-TN8410-95-273.pdf:6.68MB

None

放射線計測方法及び放射線計測装置

井崎 賢二; 森下 祐樹; 山崎 巧

金子 純一*; 樋口 幹雄*; 坪田 陽一*; 山本 誠一*; 石橋 浩之*

JP, 2015-028396  Patent licensing information  Patent publication (In Japanese)

【課題】環境中に管理対象放射性物質とそれ以外の放射性物質が混在する場合であっても、管理対象放射性物質に起因する放射能汚染を短時間に計測して評価する放射線計測方法を提供する。 【解決手段】測定試料に付着している放射性物質に感応して検出信号を発生する多数の検出ピクセルを平面状に並べて放射線検出面を構成した放射線検出器の多数の検出ピクセルから出力される検出信号を、放射線検出面を複数の領域に分割して各分割領域に該当する検出ピクセルから出力される検出信号を検出処理し、分割領域毎に検出される放射線検出結果を出力する信号処理装置を用いて測定試料中の放射性物質の放射線量を計測する。