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Journal Articles

Assessment model of radiation doses from external exposure to the public after the Fukushima Daiichi Nuclear Power Plant accident

Takahara, Shogo; Iijima, Masashi*; Watanabe, Masatoshi*

Health Physics, 118(6), p.664 - 677, 2020/06

 Times Cited Count:0 Percentile:100(Environmental Sciences)

Assessment model of radiation doses from external exposures was developed based on the actual measurement of individual doses and ambient dose equivalent rate inside and outside of a house in Fukushima city. The survey on behavioral pattern was also carried out under the same purpose. In addition to the actual measurement and survey by ourselves, we also took into account the latest insights from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Comparisons between the assessed results and the measured ones revealed that the time dependences of doses obtained using the developed models were in good agreement with the results of actual measurements. In addition, we were able to reproduce the distribution of doses for indoor and outdoor workers. Therefore, our probabilistic approach was validated. According to our assessment and actual measurement, no participants received 1 mSv/y or higher in Fukushima city in eight years after the FDNPP accident.

Journal Articles

Development of an external radiation dose estimation model for children returning to their homes in areas affected by the Fukushima Nuclear Accident

Mori, Airi; Takahara, Shogo; Yoshida, Hiroko*; Sanada, Yukihisa; Munakata, Masahiro

Health Physics, 117(6), p.606 - 617, 2019/12

 Times Cited Count:0 Percentile:100(Environmental Sciences)

Journal Articles

Computation speeds and memory requirements of mesh-type ICRP reference computational phantoms in Geant4, MCNP6, and PHITS

Yeom, Y. S.*; Han, M. C.*; Choi, C.*; Han, H.*; Shin, B.*; Furuta, Takuya; Kim, C. H.*

Health Physics, 116(5), p.664 - 676, 2019/05

 Times Cited Count:4 Percentile:30.97(Environmental Sciences)

Recently, Task Group 103 of the ICRP developed the mesh-type reference computational phantoms (MCRPs), which are planned for use in future ICRP dose coefficient calculation. Performance of major Monte Carlo particle transport codes (Geant4, MCNP6, and PHITS) were tested with MCRP. External and internal exposure of various particles and energies were calculated and the computational times and required memories were compared. Additionally calculation for voxel-mesh phantom was also conducted so that the influence of different mesh-representation in each code was studied. Memory usage of MRCP was as large as 10 GB with Geant4 and MCNP6 while it is much less with PHITS (1.2 GB). In addition, the computational time required for MRCP tends to increase compared to voxel-mesh phantoms with Geant4 and MCNP6 while it is equal or tends to decrease with PHITS.

Journal Articles

Dose estimation in recycling of decontamination soil resulting from the Fukushima NPS accident for road embankments

Takai, Shizuka; Sawaguchi, Takuma; Takeda, Seiji

Health Physics, 115(4), p.439 - 447, 2018/10

 Times Cited Count:3 Percentile:46.85(Environmental Sciences)

After the Fukushima Nuclear Power Station accident, large quantities of radiocesium-contaminated soil generated from decontamination activities have been stored in the Fukushima Prefecture. To reduce the disposal volume, the Ministry of the Environment of Japan has presented a policy to recycle low-radioactive decontamination soil limited to civil engineering structures. However, there has been no practical instance or safety assessment of decontamination soil recycling. In this study, the way of ensuring the safety for decontamination soil recycling for road embankments was discussed. First, based on Japanese construction standards, additional doses to workers and the public in construction and service scenarios were evaluated. From the result, the radioactive cesium concentration level of recycled materials, where all additional doses meet the radiation criterion of 1 mSv y$$^{-1}$$, was derived to be 6,000 Bq kg$$^{-1}$$. To confine additional doses to the public in a service scenario below 0.01 mSv y$$^{-1}$$, soil slope protection of 40 cm or more was needed. Finally, additional doses in a disaster scenario were confirmed to be below 1 mSv y$$^{-1}$$.

Journal Articles

Dose-reduction effects of vehicles against gamma radiation in the case of a nuclear accident

Takahara, Shogo; Watanabe, Masatoshi*; Hirouchi, Jun; Iijima, Masashi*; Munakata, Masahiro

Health Physics, 114(1), p.64 - 72, 2018/01


 Times Cited Count:1 Percentile:79.08(Environmental Sciences)

Journal Articles

Lessons learned in protection of the public for the accident at the Fukushima Daiichi Nuclear Power Plant

Callen, J.*; Homma, Toshimitsu

Health Physics, 112(6), p.550 - 559, 2017/06

 Times Cited Count:3 Percentile:54.72(Environmental Sciences)

What insights can the accident at the Fukushima Daiichi Nuclear Power Plant provide in the reality of decision making on actions to protect the public during a severe reactor and spent fuel pool emergency? In order to answer this question, and with the goal of limiting the consequences of any future emergencies at a nuclear power plant due to severe conditions, this article presents the main actions taken in response to the emergency in the form of a timeline. The focus of this paper are those insights concerning the progression of an accident due to severe conditions at a light water reactor nuclear power plant that must be understood in order to protect the public.

Journal Articles

Effect of remediation parameters on in-air ambient dose equivalent rates when remediating open sites with radiocesium-contaminated soil

Malins, A.; Kurikami, Hiroshi; Kitamura, Akihiro; Machida, Masahiko

Health Physics, 111(4), p.357 - 366, 2016/10


 Times Cited Count:1 Percentile:84.49(Environmental Sciences)

Journal Articles

Numerical analysis of organ doses delivered during computed tomography examinations using Japanese adult phantoms with the WAZA-ARI dosimetry system

Takahashi, Fumiaki; Sato, Kaoru; Endo, Akira; Ono, Koji*; Ban, Nobuhiko*; Hasegawa, Takayuki*; Katsunuma, Yasushi*; Yoshitake, Takayasu*; Kai, Michiaki*

Health Physics, 109(2), p.104 - 112, 2015/08

 Times Cited Count:6 Percentile:42.14(Environmental Sciences)

A dosimetry system, named WAZA-ARI, is developed to assess accurately radiation doses to persons from Computed Tomography (CT) examination patients in Japan. Organ doses were prepared to application to dose calculations in WAZA-ARI by numerical analyses using average adult Japanese human models with the Particle and Heavy Ion Transport code System (PHITS). Experimental studies clarified the radiation configuration on the table for some multi-detector row CT (MDCT) devices. Then, a source model in PHITS could specifically take into account for emissions of X-ray in each MDCT device based on the experiment results. Numerical analyses with PHITS revealed a concordance of organ doses with human body size. The organ doses by the JM phantoms were compared with data obtained using previously developed systems. In addition, the dose calculation in WAZA-ARI were verified with previously reported results by realistic NUBAS phantoms and radiation dose measurement using a physical Japanese model. The results implied that analyses using the Japanese phantoms and PHITS including source models can appropriately give organ dose data with consideration of the MDCT device and physiques of typical Japanese adults.

Journal Articles

Statistical characterization of radiation doses from external exposures and relevant contributors in Fukushima Prefecture

Takahara, Shogo; Abe, Tatsuya*; Iijima, Masashi; Shimada, Kazumasa; Shiratori, Yoshitake

Health Physics, 107(4), p.326 - 335, 2014/10


 Times Cited Count:7 Percentile:41.54(Environmental Sciences)

Probabilistic dose assessment is one of the useful methods to describe the information on the dose distributions in the population. To use this assessment, statistically characterized data on the pathway-relevant contributors are necessary. The objectives of the paper are to determine the statistical values and the distribution forms of the contributors to external exposures, as well as to identify the causes of the variabilities of them. To achieve the objectives, we have measured and surveyed ambient dose rate and time spent outdoors in Fukushima Prefecture. The measurements and surveys were performed with the cooperation of indoor workers, outdoor workers and pensioners. These results allowed us to determine the statistically characters of the individual doses and its contributors. In addition, these contributors had the variabilities attributed to the spatial distributions of deposited radionuclides, as well as the temporal and interpopulational differences of behavioral patterns.

Journal Articles

Enhanced analysis methods to derive the spatial distribution of $$^{131}$$I deposition on the ground by airborne surveys at an early stage after the Fukushima Daiichi Nuclear Power Plant accident

Torii, Tatsuo; Sugita, Takeshi*; Okada, C. E.*; Reed, M. S.*; Blumenthal, D. J.*

Health Physics, 105(2), p.192 - 200, 2013/08

 Times Cited Count:41 Percentile:2.68(Environmental Sciences)

In March 2011 the second largest accidental release of radioactivity in history occurred at the Fukushima Daiichi Nuclear Power Plant following a magnitude 9.0 earthquake and subsequent tsunami. Teams from the US Department of Energy National Nuclear Security Administration Office of Emergency Response performed aerial surveys to provide initial maps of the dispersal of radioactive material in Japan. The initial results from the surveys did not report the concentration of iodine-131 ($$^{131}$$I). This work reports on analyses performed on the initial survey data by a joint Japan-US collaboration to determine $$^{131}$$I ground concentration. As a result of this analysis, although the analytical results show a high concentration of $$^{131}$$I northwest of the NPP, consistent with the previously reported radioactive cesium ($$^{134}$$Cs and $$^{137}$$Cs) deposition, the $$^{131}$$I deposition shows a significant concentration south of the plant which is not represented in the radioactive cesium map.

Journal Articles

Decontamination of outdoor school swimming pools in Fukushima after the nuclear accident in March 2011

Saegusa, Jun; Kurikami, Hiroshi; Yasuda, Ryo; Kurihara, Kazuo; Arai, Shigeki; Kuroki, Ryota; Matsuhashi, Shimpei; Ozawa, Takashi; Goto, Hiroaki; Takano, Takao; et al.

Health Physics, 104(3), p.243 - 250, 2013/03

 Times Cited Count:3 Percentile:68.97(Environmental Sciences)

After the Nuclear accident on March 2011, water discharge from many outdoor swimming pools in the Fukushima prefecture was suspended out of concern that radiocesium in the pool water would flow into farmlands. We have reviewed the existing flocculation method for decontaminating pool water and established a practical decontamination method by demonstrating the process at several pools in the Fukushima prefecture.

Journal Articles

Estimating neutron dose equivalent rates from heavy ion reactions around 10 MeV amu$$^{-1}$$ using the PHITS code

Iwamoto, Yosuke; Ronningen, R. M.*; Niita, Koji*

Health Physics, 98(4), p.591 - 596, 2010/04

 Times Cited Count:4 Percentile:66.13(Environmental Sciences)

The influence of the "switching time" in PHITS calculations of low-energy heavy ion reactions, defined as the time when the JAERI Quantum Molecular Dynamics model calculation stops and the Generalized Evaporation Model calculation begins, was studied using neutron energy spectra from around 10 MeV/u heavy ion incident on a copper target. Using a value of 100 fm/c for the switching time, calculated neutron energy spectra obtained agree well with the experimental data. PHITS was then used with the switching time of 100 fm/c to simulate an experimental study by calculating neutron dose equivalent rates produced by 3 MeV/u to 16 MeV/u heavy ion beams incident on iron, nickel and copper targets. The calculated neutron dose equivalent rates agree very well with the data and follow a general pattern which appears to be insensitive to the heavy ion species but is sensitive to the target material.

Journal Articles

Responses of selected neutron monitors to cosmic radiation at aviation altitudes

Yasuda, Hiroshi*; Yajima, Kazuaki*; Sato, Tatsuhiko; Takada, Masashi*; Nakamura, Takashi*

Health Physics, 96(6), p.655 - 660, 2009/06

 Times Cited Count:9 Percentile:42.19(Environmental Sciences)

Cosmic radiation exposure of aircraft crew is generally evaluated by numerical simulations and those are desirably verified by measurements. We examined the applicability of selected transportable neutron monitors that are commercially available for measurements of neutron ambient dose equivalent.

Journal Articles

Development of $$^{241}$$Am lung monitoring system using an imaging plate

Hirota, Masahiro*; Kurihara, Osamu; Takada, Chie; Takasaki, Koji; Momose, Takumaro; Deji, Shizuhiko*; Ito, Shigeki*; Saze, Takuya*; Nishizawa, Kunihide*

Health Physics, 93(1), p.28 - 35, 2007/07

 Times Cited Count:4 Percentile:66.18(Environmental Sciences)

A new $$^{241}$$Am lung monitoring system without shielding was devised by using an imaging plate system. The Lawrence Livermore National Laboratory's realistic torso phantom containing a $$^{241}$$Am lung was covered by imaging plates sealed in lightproof bags. The imaging plate system displayed $$^{241}$$Am lung images characteristic of the lung shape of the torso phantom. The imaging plate system's lower detection limits of 14 Bq for 60 min exposure and 6 Bq for 300 min were the same levels as those of the phoswich detectors and the germanium detectors placed in shielded rooms. The imagingplate system for 60 min exposure detected about 2% of the annual limit of 740 Bq for $$^{241}$$Am inhalation. A lung monitoring system using imaging plates is applicable for $$^{241}$$Am lung monitoring.

Journal Articles

Concentration and daily excretion of uranium in urine of Japanese

Tolmachev, S.*; Kuwabara, Jun; Noguchi, Hiroshi

Health Physics, 91(2), p.144 - 153, 2006/08

 Times Cited Count:14 Percentile:30.44(Environmental Sciences)

Study was undertaken to investigate uranium concentrations in urine samples for nonexposed Japanese individuals and to evaluate uranium daily excretion. Uranium concentrations were measured with inductively coupled plasma mass spectrometry after microwave-assisted digestion and online separation using the UTEVA extraction chromatographic resin. The concentrations ranged from 0.8 to 35.6 ng of uranium per liter of urine (median 4.5 ng L-1). Urinary uranium was normalized relative to the creatinine concentration in order to compensate a degree of urine dilution. Creatinine-normalized values ranged from 1.2 to 17.8 ng of uranium per gram of creatinine (median 7.4 ng g-1 creatinine). These results correspond to the lower end of urinary uranium reported for nonexposed populations. Using recommended by ICRP values for 24-h creatinine excretion, level of daily excreted uranium has been calculated 6.45 ng d-1 (median value). These data along with literature data on uranium dietary intake for Japanese populations were used to estimate uranium gastrointestinal absorption fraction (f1). The median f1 value was calculated to be 0.007.

Journal Articles

Vertical profile of tritium concentration in air during a chronic atmospheric HT release

Noguchi, Hiroshi; Yokoyama, Sumi*

Health Physics, 84(3), p.344 - 353, 2003/03

 Times Cited Count:0 Percentile:100(Environmental Sciences)

no abstracts in English

Journal Articles

Isotopic ratio of $$^{129}$$I/$$^{127}$$I in seaweed measured by neutron activation analysis with $$gamma$$-$$gamma$$ coincidence

Toh, Yosuke; Hatsukawa, Yuichi; Oshima, Masumi; Shinohara, Nobuo; Hayakawa, Takehito; Kushita, Kohei; Ueno, Takashi

Health Physics, 83(1), p.110 - 113, 2002/07

 Times Cited Count:10 Percentile:42.42(Environmental Sciences)

no abstracts in English

Journal Articles

Formation and retention of organically bound deuterium in rice in deuterium water release experiment

Atarashi-Andoh, Mariko; Amano, Hikaru; Kakiuchi, Hideki; Ichimasa, Michiko*; Ichimasa, Yusuke*

Health Physics, 82(6), p.863 - 868, 2002/06

 Times Cited Count:6 Percentile:58.38(Environmental Sciences)

As a substitute of tritium, deuterium water (D2O) vapor release experiments were performed to estimate the difference of formation and subsequent retention of organically bound deuterium (OBD) in rice plants between daytime and nighttime exposure. Potted plants were exposed to deuterium water vapor in a greenhouse for 8 hours, under day and night conditions. Deuterium concentrations in free water and organic matter in rice leaves and ears were investigated until the harvest time. Data analysis was carried out using a model in which different generating processes of organic matter were considered. The calculated results agreed with the measured value.

Journal Articles

Journal Articles

An Experimental study on radiation streaming through a labyrinth in a proton accelerator facility of intermediate energy region

Tanaka, Susumu; Nakashima, Hiroshi; Sakamoto, Yukio; Nakane, Yoshihiro; Meigo, Shinichiro; Tanaka, Shunichi; Nakamura, Takashi*; Takada, Masashi*; Kurosawa, Tadahiro*; Hirayama, Hideo*; et al.

Health Physics, 81(4), p.406 - 418, 2001/10

 Times Cited Count:4 Percentile:64.97(Environmental Sciences)

no abstracts in English

71 (Records 1-20 displayed on this page)