Interdisciplinary evaluation of biological effect of internal exposure by inhaling alpha-ray emitting nuclides represented by radon (Contract research); FY2020 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Okayama University*

JAEA-Review 2021-028, 57 Pages, 2021/11

JAEA-Review-2021-028.pdf:1.94MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Interdisciplinary evaluation of biological effect of internal exposure by inhaling alpha-ray emitting nuclides represented by radon" conducted from FY2018 to FY2020. Since the final year of this proposal was FY2020, the results for three fiscal years were summarized. The present study aims to evaluate the influence of radiation exposure to alpha-ray emitting dusts generated in decommissioning of the nuclear reactors. Radon is used here as a surrogate nuclide because it is an alpha-ray emitter and there have been extensive studies on it so far.

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

https://doi.org/10.1016/j.radmeas.2020.106304

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.

PARaDIM; A PHITS-based Monte Carlo tool for internal dosimetry with tetrahedral mesh computational phantoms

Carter, L. M.*; Crawford, T. M.*; Sato, Tatsuhiko; Furuta, Takuya; Choi, C.*; Kim, C. H.*; Brown, J. L.*; Bolch, W. E.*; Zanzonico, P. B.*; Lewis, J. S.*

Journal of Nuclear Medicine, 60(12), p.1802 - 1811, 2019/12

https://doi.org/10.2967/jnumed.119.229013

Voxel human phantoms have been used for internal dose assessment. More anatomically accurate representation become possible for skins or layer tissues owing to recent developments of advanced polygonal mesh-type phantoms and thus internal dose assessment using those advanced phantoms are desired. However, the Monte Carlo transport calculation by implementing those phantoms require an advanced knowledge for the Monte Carlo transport codes and it is only limited to experts. We therefore developed a tool, PARaDIM, which enables users to conduct internal dose calculation with PHITS easily by themselves. With this tool, a user can select tetrahedral-mesh phantoms, set radionuclides in organs, and execute radiation transport calculation with PHITS. Several test cases of internal dosimetry calculations were presented and usefulness of this tool was demonstrated.

Evaluation of effective dose coefficient with variation of absorption fraction in gastrointestinal system for ingestion of radiocesium

Pratama, M. A.; Takahara, Shogo; Hato, Shinji*

Hoken Butsuri, 52(3), p.200 - 209, 2017/09

https://doi.org/10.5453/jhps.52.200

The purpose of this study is to identify the significance of the change in the intestinal absorption rate values the ( value) to the change of dose coefficient as well as to provide a list of dose coefficients which each of the value corresponds to a specific intestinal absorption rate and age groups. In the range of 0-1, 10 different values of for 1 year, 5 years old, and adult group were chosen and used in a separate calculation by using, a biokinetic compartment model, DCAL. It was found that the lower values of intestinal absorption rate lead to a significant decrease of the committed effective coefficient for adult. Oppositely for children, the decrease of committed effective coefficient was not as significant. This study also suggests that the significance of dose coefficient change due to the variation of substantially depends on the biological half-life of the radionuclide and the mass of organs and tissues in human body.

Measurement of the stochastic radial dose distribution for a 30-MeV proton beam using a wall-less tissue-equivalent proportional counter

Tsuda, Shuichi; Sato, Tatsuhiko; Ogawa, Tatsuhiko

Radiation Protection Dosimetry, 168(2), p.190 - 196, 2016/02

https://doi.org/10.1093/rpd/ncv285

Deposit energy distribution in microscopic site in a living cell is important information for understanding of biological effects of energetic heavy ion beams. In this work, a wall-less tissue equivalent proportional counter has been used for the measurement of lineal energy (y) distributions and dose-mean of y (yD) at radial direction of 30 MeV H at TIARA, for the verification of the microdosimetric function of PHITS. The measured yf(y) summed in radial direction agree with the corresponding data from the microdosimetric calculations using the PHITS code fairly well. The yD of 30 MeV proton beam presents the smallest value at r = 0.0 and gradually increase with radial distance, while the values of heavy ions such as iron showed rapid decrease with radial distance. This experimental result demonstrates that the stochastic deposit energy distribution of high-energy protons in microscopic region is rather constant both in the core and in the penumbra region of the track structure.

RCA/IAEA third external dosimetry intercomparisons in East Asia region

Yamamoto, Hideaki; Yoshizawa, Michio; Murakami, Hiroyuki; Momose, Takumaro*; Tsujimura, Norio*; Kanai, Katsuta*; Cruz-Suarez, R.*

Radiation Protection Dosimetry, 125(1-4), p.88 - 92, 2007/07

https://doi.org/10.1093/rpd/ncl539

The purpose of this paper is to discuss the results of the third intercomparison exercise of external radiation dosimetry organized under the Regional Cooperative Agreement (RCA) in the East Asia region of the International Atomic Energy Agency (IAEA). Twenty five laboratories from 16 member states participated in the exercise. Japan Atomic Energy Research Institute (JAERI) and Japan Nuclear Cycle Development Institute (JNC) arranged the standard irradiation of the participants' dosimeters. The results of the measurements of the irradiated dosimeters for the determination of external doses were satisfactory for all participants, demonstrating good performance in their external dosimetry.

LaCl(Ce) scintillation detector applications for environmental -ray measurements of low to high dose rates

Tsutsumi, Masahiro; Tanimura, Yoshihiko

Nuclear Instruments and Methods in Physics Research A, 557(2), p.554 - 560, 2006/02

https://doi.org/10.1016/j.nima.2005.11.117

A new cerium-doped LaCl(Ce) scintillator is evaluated with respect to the application in environmental -ray dosimetry and spectrometry. The scintillator is very attractive for -ray spectrometry in the case of high count rate, because it has excellent energy resolution and fast decay time. The performance characteristics of a scintillator with a 25.4 mm 25.4 mm LaCl(Ce) crystal are studied and compared to those of a NaI(Tl) scintillator with the same size crystal. Acquired pulse-height spectra are converted to dose rates by using the G(E) function method. Though the LaCl(Ce) crystal itself produces a rather high background in the crystal itself, the scintillator provides good energy information and dose-rate readings from low to high-level (several mGy/h) by subtracting the self-background. The properties of LaCl(Ce) scintillator suggest that the scintillator could be a promising candidate for monitoring at high-dose levels as in emergencies, as well as at ordinary levels of background radiation.

Annual report on the activities of Health Physics in JAERI in 2004; April 1, 2004March 31, 2005

Department of Health Physics; Safety Division, Naka; Safety Division, Takasaki; Radiation Control Division, Oarai; Safety Division, Kansai; Operation Safety Administration Division, Mutsu

JAERI-Review 2005-028, 232 Pages, 2005/08

JAERI-Review-2005-028.pdf:13.23MB

no abstracts in English

Application of invasion mathematical model in dosimetry for boron neutron capture therapy for malignant glioma

Yamamoto, Kazuyoshi; Kumada, Hiroaki; Nakai, Kei*; Endo, Kiyoshi*; Yamamoto, Tetsuya*; Matsumura, Akira*

Proceedings of 11th World Congress on Neutron Capture Therapy (ISNCT-11) (CD-ROM), 14 Pages, 2004/10

A dose distribution considered the tumor cell density distribution is required on the radiation therapy. We propose a novel method of determining target region considering the tumor cell concentration as a new function for the next generation Boron Neutron Capture Therapy (BNCT) dosimetry system. It has not been able to sufficiently define the degree of microscopic diffuse invasion of the tumor cells peripheral to a tumor bulk in malignant glioma using current medical imaging. Referring to treatment protocol of BNCT, the target region surrounding the tumor bulk has been set as the region which expands at the optional distance with usual 2cm margin from the region enhanced on T1 weighted gadolinium Magnetic Resonance Imaging (MRI). In this research, the cell concentration of the region boundary of the target was discussed by using tumor cell diffusion model in the sphere spatio-temporal system. The survival tumor cell density distribution after the BNCT irradiation was predicted by the two regions diffusion model for a virtual brain phantom.

Energy dependence of absorbed dose distributions in a soft tissue substitute for neutron dosimetry

Tsuda, Shuichi; Endo, Akira; Yamaguchi, Yasuhiro

Journal of Nuclear Science and Technology, 41(Suppl.4), p.132 - 135, 2004/03

http://www.tandfonline.com/doi/abs/10.1080/00223131.2004.10875663

A solid material improved in hydrogen and oxygen contents was synthesized for development of a physical phantom for neutron. The elemental composition and density are aimed for those of the soft tissue in ICRU Report 44. The soft tissue equivalence has been verified by an absorbed dose measurement using a 252Cf neutron source. In the present work, absorbed doses were measured for the purpose of examinations of the characteristic of the synthesized soft tissue substitute for neutron of various energies, using mono-energetic 0.565 MeV neutrons from Li(p,n) reaction and 5 MeV from D(d,n) reaction, and quasi-mono-energetic ones (40 and 65 MeV) produced via Li(p,n) reaction. The measured absorbed doses were compared with those calculated by Monte Carlo simulation codes. The results indicate that the tissue substitute has a characteristic of soft tissue equivalence for neutron in the energy range from several hundred keV up to approximately 100 MeV.