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Morishita, Yuki; Yamamoto, Seiichi*; Momose, Takumaro; Kaneko, Junichi*; Nemoto, Norio
Radiation Protection Dosimetry, 178(4), p.414 - 421, 2018/03
Times Cited Count：0 Percentile：0.01(Environmental Sciences)Plutonium dioxide (PuO
) is used to fabricate a mixed oxide fuel for fast breeder reactors. When a glove box containing PuO fails, such as by rupture of a glove or a vinyl bag, airborne contamination of plutonium (Pu) can occur. If the worker inhale PuO particles, they deposit in the lung and cause lung cancer. The nasal smear and nose blow methods are useful for checking workers for PuO intake in the field. However, neither method can evaluate the quantitative activity of Pu. No alpha-particle detector that can be used for direct measurements in the nasal cavity has been developed. Therefore, we developed a nasal monitor capable of directly measuring the activity of Pu in the nasal cavity to precisely evaluate the internal exposure dose of a worker. Prismatic-shaped 2
2 acrylic light guides were used to compose a detector block, and a ZnS(Ag) scintillator was adhered to the surface of these light guides. Silicon photomultiplier (SiPM) arrays with 88 channels were used as a photodetector. Actual PuO particles were measured using the nasal monitor. The nasal monitor could be directly inserted in the nasal cavities. The activity distribution of Pu was obtained by the nasal monitor. The average efficiencies in 4
were 11.43% and 11.58% for the left and right nasal cavities, respectively. The effect of 
and 
rays on the detection of the alpha particles of Pu was negligible. The difference in the measured Pu activity between the ZnS(Ag) scintillation counter and the nasal monitor was within 4.0%. The developed nasal monitor can solve the uncertainty problem encountered with the nasal smear and the nose blow methods. We expect this monitor to be useful for accurately estimating the internal exposure dose of workers.
Morishita, Yuki; Yamamoto, Seiichi*; Izaki, Kenji; Kaneko, Junichi*; Nemoto, Norio
Radiation Measurements, 103, p.33 - 38, 2017/08
Times Cited Count：14 Percentile：78.05(Nuclear Science & Technology)Nuclear fuel materials, such as uranium and plutonium (Pu), are handled at nuclear fuel facilities. There are a contamination source of Pu in tight spaces that cannot be directly measured by a ZnS(Ag) scintillation detector, such as interspace between a glovebox window and a platform, pipe flange, port cover of vinyl bag, and filter interspaces. Therefore, we developed a new imaging detector called a flexible alpha camera that enables to identify the Pu contamination for tight spaces at work sites. The thickness of the flexible alpha camera was only 
1/5 of the ZnS(Ag) scintillation detector, and its efficiency for 4-pi direction was 42.7% for 5.5-MeV alpha particles. Minimal detectable activity (MDA) was 0.014 Bq. Four types of PuO sample, removed from a duct, Bag-In/Bag-Out port, glovebox glove, and vinyl sheet, were measured by the flexible alpha camera and the PuO particle was automatically identified. Using the flexible alpha camera, the Pu contamination source can be quickly detected, preventing the spread of contamination.
Horikoshi, Yoshinori; Nemoto, Norio; Kurosawa, Shigeyuki*; Takasaki, Koji; Mizuniwa, Harumi
JAEA-Testing 2008-003, 29 Pages, 2008/04
JAEA-Testing-2008-003.pdf:1.65MB
In the Plutonium Fuel Technical Development Center, protective clothing suitable for sweltering radiation work was examined. Since it worried about the influence of wet protective clothing with sweat on detection of MOX powder contamination, Detection situations, the diffusion of contamination, and the osmosis and penetrability to wet protective clothing were examined about the present fabric and other new fabrics. As a result of examination, it was confirmed that the influence of detection on alpha ray in the wet condition of new fabrics was smaller than the current fabric. This report compiled the result of examination and points in the fabric selection suitable for protective clothing.
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.
Makihara, Akiko*; Shindo, Hiroyuki*; Nemoto, Norio*; Kuboyama, Satoshi*; Matsuda, Sumio*; Oshima, Takeshi; Hirao, Toshio; Ito, Hisayoshi; Buchner, S.*; Campbell, A. B.*
IEEE Transactions on Nuclear Science, 47(6), p.2400 - 2404, 2000/12
Times Cited Count：33 Percentile：87.34(Engineering, Electrical & Electronic)no abstracts in English
Iwamoto, Seikichi; Takeuchi, Norio; Onoma, Katsuyuki; Nemoto, Masahiro*
JAERI-Tech 2000-055, 15 Pages, 2000/09
JAERI-Tech-2000-055.pdf:1.17MB
no abstracts in English
Makihara, Akiko*; Shindo, Hiroyuki*; Nemoto, Norio*; Kuboyama, Satoshi*; Matsuda, Sumio*; Oshima, Takeshi; Hirao, Toshio; Ito, Hisayoshi; Buchner, S.*; Campbell, A. B.*
Proceedings of 4th International Workshop on Radiation Effects on Semiconductor Devices for Space Application, p.103 - 107, 2000/00
no abstracts in English
Nemoto, Norio*; Akutsu, Takeo*; Naito, Ichiro*; Matsuda, Sumio*; Ito, Hisayoshi; Agematsu, Takashi; Kamiya, Tomihiro; Nashiyama, Isamu
JAERI-Conf 97-003, p.234 - 236, 1997/03
no abstracts in English
-ray irradiated 3C-SiC MOS structureNemoto, Norio*; Yoshikawa, Masahito; Nashiyama, Isamu; Yoshida, Sadafumi*; Onishi, Kazunori*
Heisei-5-Nendo (Dai-37-Kai) Nihon Daigaku Riko Gakubu Gakujutsu Koenkai Koen Rombunshu; Zairyo, Bussei, p.149 - 150, 1993/00
no abstracts in English
Yokomizo, Hideaki; Takeuchi, Hiroshi; Sugie, Tatsuo; Ogiwara, Norio; Sato, Masayasu; Nagashima, Akira; ; Nakamura, Yukiharu; Nishitani, Takeo; Neyatani, Yuzuru; et al.
Fusion Engineering and Design, 5, p.117 - 138, 1987/00
Times Cited Count：15 Percentile：79.7(Nuclear Science & Technology)no abstracts in English
Nemoto, Norio
no journal, ,
no abstracts in English
Morifuji, Masayuki; Nemoto, Norio
no journal, ,
no abstracts in English
Okano, Masanori; Goto, Yuichi; Jitsukata, Shu*; Nemoto, Hirokazu*; Takano, Masato; Komoto, Norio; Kuno, Takehiko; Yamada, Keiji
no journal, ,
no abstracts in English
Morishita, Yuki; Yamamoto, Seiichi*; Izaki, Kenji; Nemoto, Norio; Kashimuta, Yoshio*
no journal, ,
Nuclear fuel materials such as uranium and plutonium were handled at a nuclear fuel facility. Early detection of a contamination due to these materials is important to prevent internal exposure of workers. ZnS(Ag) scintillation detector has been widely used to detect these materials by measuring alpha-particles. It cannot directly measure narrow space. ZnS(Ag) scintillation detector does not have an ability to distinguish nuclear fuel materials from naturally occurring alpha emitters such as radon daughters. To solve this problem, we developed a new imaging detector named "flexible alpha camera". We actually measured plutonium specimen and radon daughters by the flexible alpha camera. In the result of 2-dimensional distribution, plutonium specimen was imaged as point. Spatial resolution of plutonium specimen was only 0.36 mm FWHM. Plutonium was distinguished from radon daughters based on differences of 2-dimensional distribution and energy by using the flexible alpha camera.
Morishita, Yuki; Yamamoto, Seiichi*; Momose, Takumaro; Kaneko, Junichi*; Nemoto, Norio
no journal, ,
Plutonium dioxide (PuO) is used to fabricate mixed oxide fuel for fast breeder reactors. When airborne contamination of Pu occurs, the presence of Pu in the nasal cavity of a worker should be instantly evaluated. The nasal smear method is usual method to immediately evaluate the intake of PuO at a work site. However, this method cannot evaluate the activity of Pu quantitatively because the removable factor of PuO can be changed by the nasal swab and the pressure of a finger. An alpha-particle detector that can directly measure the nasal cavity has not yet been developed. Therefore, we developed a nasal monitor that can directly measure the activity of Pu in the nasal cavity in order to exactly evaluate the internal exposure dose of a worker. For our device, a ZnS(Ag) scintillator was attached to the surface of a 3 mm 3 mm 20 mm prismatic-shaped light guide. A Silicon Photomultiplier (SiPM) array was used to detect the scintillation light from the ZnS (Ag) scintillator. 
Am source was collimated to 2 mm 5 mm and was used to evaluate the efficiency of the nasal monitor. Alpha particles were irradiated from three different faces to the scintillator for the left and right nasal cavities. In addition, the effects of gamma and beta rays on the nasal monitor were evaluated. The positions of both the left and right nasal cavities could be identified based on the two-dimensional distribution of the alpha particles. The average efficiency was comparable to the ZnS(Ag) scintillation survey meter. The effect of the gamma and beta rays was negligible for Pu monitoring. Considering these efficiencies and the self-absorption factor of alpha particles, the exact activity of Pu in the nasal cavity can be instantly evaluated.
Tamura, Ken; Nemoto, Norio; Isozaki, Kohei
no journal, ,
no abstracts in English
