Background radiation monitoring via manned helicopter and development of technology for radiation monitoring via unmanned airplane for application of nuclear emergency response technique in the fiscal year 2022 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Sasaki, Miyuki; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Haginoya, Masashi*; Matsunaga, Yuki*; Akutsu, Yuichiro*; Arai, Yoshinori*; et al.

JAEA-Technology 2023-026, 161 Pages, 2024/03

JAEA-Technology-2023-026.pdf:14.66MB

By the accident at Tokyo Electric Power Company's (TEPCO's) Fukushima Daiichi Nuclear Power Station (FDNPS), caused by tsunami triggered by the 2011 off the Pacific coast of Tohoku Earthquake, a large amount of radioactive material was released into the surrounding environment. After the accident, Airborne Radiation Monitoring (ARM) via manned helicopter has been utilized as a method to quickly and extensively measure radiation distribution surrounding FDNPS. In order to utilize ARM and to promptly provide the results during a nuclear emergency, information on background radiation levels, topographical features, and controlled airspace surrounding nationwide nuclear facilities have been prepared in advance. In the fiscal year 2022, we conducted ARM around the Mihama Nuclear Power Station of Kansai Electric Power Company (KEPCO), the Tsuruga Power Station of Japan Atomic Power Company (JAPC), and the Ikata Power Station of Shikoku Electric Power Company (YONDEN), and prepared information on background radiation doses and controlled airspace. In addition, we have developed an aerial radiation detection system via unmanned airplane, which is expected to be an alternative to ARM, during a nuclear emergency. This report summarizes the results and technical issues identified.

Background radiation monitoring using manned helicopter for application of technique of nuclear emergency response in the fiscal year 2020 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Sasaki, Miyuki; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Sato, Kazuhiko*; Haginoya, Masashi*; Matsunaga, Yuki*; Kikuchi, Hikaru*; et al.

JAEA-Technology 2021-020, 138 Pages, 2021/11

JAEA-Technology-2021-020.pdf:17.11MB

A large amount of radioactive material was released by the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company, caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011. After the nuclear disaster, airborne radiation monitoring via manned helicopter has been utilized to grasp rapidly and widely the distribution of the radioactive materials surrounding FDNPS. We prepare the data of background radiation dose, geomorphic characteristics and the controlled airspace surrounding nuclear facilities of the whole country in order to make effective use of the monitoring technique as a way of emergency radiation monitoring and supply the results during an accident of a facility. This report is summarized that the knowledge as noted above achieved by the aerial radiation monitoring around Tsuruga and Mihama nuclear power station, research reactors in Kindai University Atomic Energy Research Institute and Institute for Integrated Radiation and Nuclear Science, Kyoto University. In addition, examination's progress aimed at introduction of airborne radiation monitoring via unmanned plane during nuclear disaster and the technical issues are summarized in this report.

A Unique high natural background radiation area; Dose assessment and perspectives

Hosoda, Masahiro*; Nugraha, E. D.*; Akata, Naofumi*; Yamada, Ryohei; Tamakuma, Yuki*; Sasaki, Michiya*; Kelleher, K.*; Yoshinaga, Shinji*; Suzuki, Takahito*; Rattanapongs, C. P.*; et al.

Science of the Total Environment, 750, p.142346_1 - 142346_11, 2021/01

https://doi.org/10.1016/j.scitotenv.2020.142346

The biological effects of low dose-rate radiation exposures on humans remains unknown. In fact, the Japanese nation still struggles with this issue after the Fukushima Dai-ichi Nuclear Power Plant accident. Recently, we have found a unique area in Indonesia where naturally high radiation levels are present, resulting in chronic low dose-rate radiation exposures. We aimed to estimate the comprehensive dose due to internal and external exposures at the particularly high natural radiation area, and to discuss the enhancement mechanism of radon. A car-borne survey was conducted to estimate the external doses from terrestrial radiation. Indoor radon measurements were made in 47 dwellings over three to five months, covering the two typical seasons, to estimate the internal doses. Atmospheric radon gases were simultaneously collected at several heights to evaluate the vertical distribution. The absorbed dose rates in air in the study area vary widely between 50 nGy h and 1109 nGy h. Indoor radon concentrations ranged from 124 Bq m to 1015 Bq m. That is, the indoor radon concentrations measured exceed the reference levels of 100 Bq m recommended by the World Health Organization. Furthermore, the outdoor radon concentrations measured were comparable to the high indoor radon concentrations. The annual effective dose due to external and internal exposures in the study area was estimated to be 27 mSv using the median values. It was found that many residents are receiving radiation exposure from natural radionuclides over the dose limit for occupational exposure to radiation workers. This enhanced outdoor radon concentration might be as a result of the stable atmospheric conditions generated at an exceptionally low altitude. Our findings suggest that this area provides a unique opportunity to conduct an epidemiological study related to health effects due to chronic low dose-rate radiation exposure.

Role of filamentous fungi in migration of radioactive cesium in the Fukushima forest soil environment

Onuki, Toshihiko; Sakamoto, Fuminori; Kozai, Naofumi; Namba, Kenji*; Neda, Hitoshi*; Sasaki, Yoshito; Niizato, Tadafumi; Watanabe, Naoko*; Kozaki, Tamotsu*

Environmental Science; Processes & Impacts, 21(7), p.1164 - 1173, 2019/07

https://doi.org/10.1039/C9EM00046A

The fate of radioactive Cs deposited after the Fukushima nuclear power plant accident and its associated radiological impacts are largely dependent on its mobility from surface soils to forest ecosystems. We measured the accumulation of radioactive Cs in the fruit bodies of wild fungi in the forest at Iidate, Fukushima, Japan. The transfer factors (TFs) of radioactive Cs from soil to the fruit bodies of wild fungi were between 10 to 10, a range similar to those reported for the fruit bodies collected in Europe after the Chernobyl accident and in parts of Japan contaminated by nuclear bomb test fallout. Comparison of the TFs of the wild mushroom and that of the fungal hyphae of 704 stock strains grown on agar medium containing nutrients and radioactive Cs showed that the TFs of wild mushroom were lower. TF was less than 0.1 after addition of the minerals zeolite, vermiculite, phlogopite, smectite, or illite of 1% weight to the agar medium. These results indicate that the presence of minerals decrease Cs uptake by fungi grown in the agar medium.

Nanoscopic structural investigation of physically cross-linked nanogels formed from self-associating polymers

Sekine, Yurina; Endo, Hitoshi*; Iwase, Hiroki*; Takeda, Shigeo*; Mukai, Sadaatsu*; Fukazawa, Hiroshi; Littrell, K. C.*; Sasaki, Yoshihiro*; Akiyoshi, Kazunari*

Journal of Physical Chemistry B, 120(46), p.11996 - 12002, 2016/11

https://doi.org/10.1021/acs.jpcb.6b06795

The detailed structure of a nanogel formed by self-association of cholesterol-bearing pullulans (CHP) was determined by contrast variation small-angle neutron scattering. The decomposition of scattering intensities into partial scattering functions of each CHP nanogel component, i.e., pullulan, cholesterol, and the cross-term between the pullulan and the cholesterol allows us to investigate the internal structure of the nanogel. The effective spherical radius of the skeleton formed by pullulan chains was found to be about 8.1 nm. In the CHP nanogel, there are about 19 cross-linking points where a cross-linking point is formed by aggregation of trimer cholesterol molecules with the spatially inhomogeneous distribution of the mass fractal dimension of 2.6. The average radius of the partial chains can also be determined to be 1.7 nm. As the result, the complex structure of the nanogels is coherently revealed at the nanoscopical level.

Measurement of the spin-flip value in hypernuclei

Sasaki, Yuki*; Ekawa, Hiroyuki; Hasegawa, Shoichi; Hayakawa, Shuhei; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Sako, Hiroyuki; Sato, Susumu; Sugimura, Hitoshi; et al.

JPS Conference Proceedings (Internet), 8, p.022013_1 - 022013_4, 2015/09

https://doi.org/10.7566/JPSCP.8.022013

High-energy spin and charge excitations in electron-doped copper oxide superconductors

Ishii, Kenji; Fujita, Masaki*; Sasaki, Takanori*; Minola, M.*; Dellea, G.*; Mazzoli, C.*; Kummer, K.*; Ghiringhelli, G.*; Braicovich, L.*; Toyama, Takami*; et al.

Nature Communications (Internet), 5, p.3714_1 - 3714_8, 2014/04

https://doi.org/10.1038/ncomms4714

Shielding study at the Fukui Prefectural Hospital Proton Therapy Center

Satoh, Daiki; Maeda, Yoshikazu*; Tameshige, Yuji*; Nakashima, Hiroshi; Shibata, Tokushi*; Endo, Akira; Tsuda, Shuichi; Sasaki, Makoto*; Maekawa, Motokazu*; Shimizu, Yasuhiro*; et al.

Journal of Nuclear Science and Technology, 49(11), p.1097 - 1109, 2012/11

https://doi.org/10.1080/00223131.2012.730900

At the Fukui Prefectural Hospital Proton Therapy Center, neutron doses behind concrete shields and at maze have been measured by using radiation monitors, DARWIN, Wendi-2, a rem meter, and solid state nuclear track detectors. The measured data were compared with the estimations by analytical models and Monte Carlo code PHITS. The analytical model with the parameters employed in shielding design of the facility gave considerably larger estimates than the measured data. This means that the facility was designed with an enough safety margin. The calculation results of PHITS were less than those of the analytical model, and were about 3 times larger than the measured data. From the view point of a safety policy with conservative estimation for shielding design, Monte Carlo simulation is a better tool for estimating radiation safety at accelerator-based proton treatment facilities.

Measurement of lineal energy distribution of heavy ion using wall-less tissue equivalent proportional counter

Tsuda, Shuichi; Sato, Tatsuhiko; Takahashi, Fumiaki; Satoh, Daiki; Sasaki, Shinichi*; Namito, Yoshihito*; Iwase, Hiroshi*; Ban, Shuichi*; Takada, Masashi*

KEK Proceedings 2011-8, p.100 - 108, 2011/12

http://www-lib.kek.jp/cgi-bin/kiss_prepri.v8?KN=201125008exit=8.

Deposit energy distribution in microscopic site is basic information for understanding of biological effects of energetic heavy ion beams. To estimate RBE, lineal energy, y, can be an appropriate physical index. In this work, a wall-less tissue equivalent proportional counter has been designed and used for the measurement of y distributions, , for 160 MeV H, 150 MeV/u He and 490 MeV/u Si ion beams. Data of and the dose-means of , , were compared with those calculated by the microdosimetric function of PHITS. It is found that the calculated and agree fairly well with those measured, as well as the already reported result of 290 MeV/u carbon beam.

Analysis of the effect of structural materials in a wall-less tissue-equivalent proportional counter irradiated by 290 MeV u carbon beam

Tsuda, Shuichi; Sato, Tatsuhiko; Takahashi, Fumiaki; Satoh, Daiki; Endo, Akira; Sasaki, Shinichi*; Namito, Yoshihito*; Iwase, Hiroshi*; Ban, Shuichi*; Takada, Masashi*

Radiation Protection Dosimetry, 143(2-4), p.450 - 454, 2011/02

https://doi.org/10.1093/rpd/ncq536

A wall-less tissue equivalent proportional counter, wall-less TEPC, has been designed and used for the measurement of the y distributions for energetic heavy ions in order to verify a biological dose calculation model incorporated in the PHITS code. It is found that the dose-mean value of y obtained by the wall-less TEPC is 50 - 60% of the LET of the argon ions in water, since the delta-rays with relatively low y can be measured.