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JAEA Reports

Data of radon measurement in underground facilities of Mizunami Underground Research Laboratory

Aoki, Katsunori; Yamanaka, Hiroki*; Watanabe, Kazuhiko*; Sugihara, Kozo

JAEA-Data/Code 2020-018, 45 Pages, 2021/02

JAEA-Data-Code-2020-018.pdf:4.54MB
JAEA-Data-Code-2020-018-appendix(DVD-ROM).zip:6.8MB

Mizunami Underground Research Laboratory (MIU) Project is pursued by Japan Atomic Energy Agency (JAEA) in the crystalline host rock (granite) as a part of geoscientific study of JAEA, and underground facilities of MIU are constructed down to 500m blow the ground surface. As small amount of Uranium is normally contained in granite, high concentration of radon is sometimes detected in the air of the underground facilities constructed in granitic rocks depending on their ventilation conditions. Radon concentrations in underground facilities of MIU have been measured according to the excavation progress of underground facilities or the change of ventilation system. It is recognized that the data obtained by the actual measurement of radon concentration in such underground facilities are rare and valuable. This repot summarizes the measured data from fiscal 2010 to fiscal 2020, together with the information of ventilation conditions and air temperature which affect radon concentrations in underground facilities. The variation of the equilibrium factors of radon is also examined with the actually measured data. As a result, it has been found that radon concentration in the drift is high in summer and low in winter according to the natural ventilation caused by the seasonal temperature difference between in and out of the underground facilities. Furthermore, the temporary increase in the equilibrium factor of radon in the drift at the start of ventilation is supposed to be due to the aerosol increase by the ventilation flow, such as the dust blown up.

Journal Articles

Lens dosimetry study in $$^{90}$$Sr+$$^{90}$$Y beta field; Full-face mask respirator shielding and dosemeter positioning

Tsujimura, Norio; Hoshi, Katsuya; Yamazaki, Takumi; Momose, Takumaro; Aoki, Katsunori; Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Yokoyama, Sumi*

KEK Proceedings 2020-5, p.21 - 28, 2020/11

Journal Articles

Measurements of the doses of eye lens for the workers of Fukushima Daiichi Nuclear Power Plant

Yokoyama, Sumi*; Ezaki, Iwao*; Tatsuzaki, Hideo*; Tachiki, Shuichi*; Hirao, Kazushige*; Aoki, Katsunori; Tanimura, Yoshihiko; Hoshi, Katsuya; Yoshitomi, Hiroshi; Tsujimura, Norio

Radiation Measurements, 138, p.106399_1 - 106399_5, 2020/11

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Journal Articles

Eye lens dosimetry for workers at Fukushima Daiichi Nuclear Power Plant, 2; Field study using humanoid phantoms

Tsujimura, Norio; Hoshi, Katsuya; Aoki, Katsunori; Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Yokoyama, Sumi*

Radiation Measurements, 134, p.106305_1 - 106305_5, 2020/06

 Times Cited Count:1 Percentile:39.17(Nuclear Science & Technology)

Journal Articles

Eye lens dosimetry for workers at Fukushima Daiichi Nuclear Power Plant, 1; Laboratory study on the dosemeter position and the shielding effect of full face mask respirators

Hoshi, Katsuya; Yoshitomi, Hiroshi; Aoki, Katsunori; Tanimura, Yoshihiko; Tsujimura, Norio; Yokoyama, Sumi*

Radiation Measurements, 134, p.106304_1 - 106304_5, 2020/06

 Times Cited Count:2 Percentile:39.17(Nuclear Science & Technology)

In FY 2017, the Japanese Nuclear Regulatory Agency (NRA) established the Radiation Safety Research Promotion Fund for funding projects on nuclear safety regulation, and adopted the two-year research project entitled "Study on standard eye lens monitoring, suitable dose management and radiation protection for nuclear and medical workers". The study is a two-phase study: a laboratory study on the eye lens dosemeter's characteristics to photons, and a field study executed at actual workplaces at Fukushima Daiichi Nuclear Power Station. This paper summarizes the results of the first-phase study, which was designed to clarify the eye lens dosemeter positioning and the shielding effect of full face mask respirators used at the station. No marked difference was observed in readings of the dosemeters attached on the different positions on the head phantom. Two types of full face mask respirators provided insignificant shielding effect for photons of 83 keV to 662 keV.

Journal Articles

A Remote continuous air monitoring system for measuring airborne alpha contamination

Morishita, Yuki; Usami, Hiroshi; Furuta, Yoshihiro; Aoki, Katsunori; Tsurudome, Koji; Hoshi, Katsuya; Torii, Tatsuo

Radiation Protection Dosimetry, 189(2), p.172 - 181, 2020/04

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

We developed a remote continuous air monitoring (RCAM) system. The RCAM system consisted of a personal air monitor and a robot. The personal air monitor (poCAMon, SARAD, Germany) had a 400 mm$$^{2}$$ ion-injected silicon detector and a membrane air filter with 25 mm-diameter. The personal air monitor provides the alpha energy spectra for any measurement time interval. Demonstration measurements were taken underground at the Mizunami Underground Research Laboratory (MIU) and at a poorly ventilated concrete building. The RCAM system was remotely operated and successfully measured the $$^{222}$$Rn progeny even though the relative humidity (RH) was almost 100%. In the measured alpha spectra, the peaks of $$^{218}$$Po (6.0 MeV alpha) and $$^{214}$$Po (7.7 MeV alpha) were clearly identified. Our developed monitor is promising for alpha dust monitoring in a high gamma-ray environment or contaminated areas where a worker cannot safely physically enter.

Journal Articles

Calculation of equivalent dose for the lens of the eye in a positron field using EGS5

Yokoyama, Sumi*; Aoki, Katsunori

Progress in Nuclear Science and Technology (Internet), 4, p.788 - 792, 2014/04

The equivalent dose rate per positron fluence for the human eye lens is calculated using a Monte Carlo simulation code, EGS5, with two mathematical models (a computational head voxel phantom and a simple eye model). The eye lens doses for medical staff and carers as received from a radiopharmaceutical such as 18F-FDG, which is used in PET examinations, when spilled on the floor, and from positrons passing through a thin injection tube are calculated using a simple eye model. At energies less than 1 MeV, the equivalent dose for the eye lens per electron and positron fluence as calculated using the simple eye model was a maximum of three orders of magnitude lower than that for the head voxel phantom. These values for the simple eye model were equal to the calculation results obtained using the eye lens model in ICRP Publication 116 and those reported in past studies. The eye lens dose rates from the point and tube sources of 18F-FDG as calculated using our simple eye model are about 0.57 and 0.37 $$mu$$Sv min$$^{-1}$$ MBq$$^{-1}$$ at 5 cm, respectively. The doses at 10 cm were one-third to half of those at 5 cm.

Journal Articles

Eu isotope measurements on single SiC grains from the Murchison meteorite; A New probe of s-process conditions in parent Asymptotic Giant Branch stars

Terada, Kentaro*; Ito, Katsunori*; Hidaka, Hiroshi*; Yoshida, Takashi*; Iwamoto, Nobuyuki; Aoki, Wako*; Williams, I. S.*

New Astronomy Reviews, 50(7-8), p.582 - 586, 2006/10

 Times Cited Count:6 Percentile:21.56(Astronomy & Astrophysics)

Europium isotopic composition could be a good probe to investigate the neutron capture process in Asymptotic Giant Branch stars (AGB stars) and/or supernovae, because the $$^{151}$$Sm and $$^{153}$$Sm branchings are sensitive to the neutron densities and temperature. Here, we report Eu isotopic analyses of single SiC grains from primitive meteorites using the sensitive high resolution ion microprobe. The results are compared with Eu isotopic ratios predicted from the s-process model of AGB stars. The observed Eu isotopic composition of SiC grains place constraints on s-process conditions such as the temperature and neutron densities in AGB stars.

Oral presentation

Spectroscopic measurement of LX-rays emitted by transuranium elements using TES microcalorimeter

Maeda, Makoto*; Maehata, Keisuke*; Iyomoto, Naoko*; Ishibashi, Kenji*; Takasaki, Koji; Nakamura, Keisuke; Aoki, Katsunori; Mitsuda, Kazuhisa*; Tanaka, Keiichi*

no journal, , 

no abstracts in English

Oral presentation

The Spectroscopy of LX-rays emitted from transuranium element using transition edge sensor microcalorimeter

Nakamura, Keisuke; Maeda, Makoto*; Aoki, Katsunori; Yasumune, Takashi; Takasaki, Koji; Maehata, Keisuke*; Iyomoto, Naoko*; Ishibashi, Kenji*; Mitsuda, Kazuhisa*; Tanaka, Keiichi*

no journal, , 

no abstracts in English

Oral presentation

Study of high resolution spectroscopy of LX-rays emitted from TRU using TES microcalorimeter

Nakamura, Keisuke; Aoki, Katsunori; Takasaki, Koji; Maeda, Makoto*; Maehata, Keisuke*; Iyomoto, Naoko*; Ishibashi, Kenji*; Mitsuda, Kazuhisa*; Tanaka, Keiichi*

no journal, , 

no abstracts in English

Oral presentation

Measurement of radon concentration and dose evaluation in the galleries at the Mizunami Underground Research Laboratory

Aoki, Katsunori; Ogura, Hideki; Kubota, Mitsuru; Tsurudome, Koji; Ikeda, Koki; Nagasaki, Yasushi; Ogata, Nobuhisa; Furuta, Sadaaki*

no journal, , 

no abstracts in English

Oral presentation

Measurement of radon concentration and dose evaluation in the galleries of 500m depth at the Mizunami Underground Research Laboratory

Aoki, Katsunori; Ogura, Hideki; Ogata, Nobuhisa; Ikeda, Koki; Nagasaki, Yasushi; Tsurudome, Koji; Furuta, Sadaaki*

no journal, , 

no abstracts in English

Oral presentation

Eye lens dosimetry for workers at Fukushima Daiichi Nuclear Power Station, 3; Evaluation of eye lens dose based on the $$gamma$$-ray spectroscopy

Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Hoshi, Katsuya; Aoki, Katsunori; Tsujimura, Norio; Yokoyama, Sumi*

no journal, , 

no abstracts in English

Oral presentation

Eye lens dosimetry for workers at Fukushima Daiichi Nuclear Power Station, 5; Photon response of eye lens dosemeters on head phantom

Tsujimura, Norio; Yoshitomi, Hiroshi; Hoshi, Katsuya; Aoki, Katsunori; Tanimura, Yoshihiko; Nishino, Sho; Yokoyama, Sumi*

no journal, , 

no abstracts in English

Oral presentation

Eye lens dosimetry for workers at Fukushima Daiichi Nuclear Power Station, 4; Evaluation of eye lens dose based on the beta-ray spectrometry

Hoshi, Katsuya; Tsujimura, Norio; Aoki, Katsunori; Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Yokoyama, Sumi*

no journal, , 

no abstracts in English

Oral presentation

Eye lens dosimetry for workers at Fukushima Daiichi Nuclear Power Station, 1; Outline of the research and results of dose measurement for the workers

Yokoyama, Sumi*; Ezaki, Iwao*; Aoki, Katsunori; Tatsuzaki, Hideo*; Hirao, Kazushige*; Tachiki, Shuichi*; Yoshitomi, Hiroshi; Hoshi, Katsuya; Tanimura, Yoshihiko; Oguchi, Hiroyuki*; et al.

no journal, , 

no abstracts in English

Oral presentation

Eye lens dosimetry for workers at Fukushima Daiichi Nuclear Power Station, 2; Summary of personal dose measurement and dosimeter comparison

Ezaki, Iwao*; Aoki, Katsunori; Tatsuzaki, Hideo*; Tachiki, Shuichi*; Hirao, Kazushige*; Yoshitomi, Hiroshi; Hoshi, Katsuya; Tanimura, Yoshihiko; Oguchi, Hiroyuki*; Tsujimura, Norio; et al.

no journal, , 

no abstracts in English

Oral presentation

Study of eye lens dosimetry for workers at Fukushima Daiichi Nuclear Power Station, 2; Relationship of the personal dosimetry obtained from phantom experiments and workers

Aoki, Katsunori; Yokoyama, Sumi*; Hoshi, Katsuya; Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Tsujimura, Norio

no journal, , 

no abstracts in English

Oral presentation

Study of eye lens dosimetry for workers at Fukushima Daiichi Nuclear Power Station, 1; Results of field experiments using an anthropomorphic phantom

Hoshi, Katsuya; Tsujimura, Norio; Aoki, Katsunori; Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Yokoyama, Sumi*

no journal, , 

no abstracts in English

23 (Records 1-20 displayed on this page)