A Step-by-step simulation code for estimating yields of water radiolysis species based on electron track-structure mode in the PHITS code

Matsuya, Yusuke; Yoshii, Yuji*; Kusumoto, Tamon*; Akamatsu, Ken*; Hirata, Yuho; Sato, Tatsuhiko; Kai, Takeshi

Physics in Medicine & Biology, 19 Pages, 2023/00

https://doi.org/10.1088/1361-6560/ad199b

Time-dependent yields of chemical products resulted in water radiolysis play a great role in evaluating DNA damage response after exposure to ionizing radiation. Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo simulation code for radiation transport, which allows to determine several atomic interactions such as ionizations and electronic excitations as physical stage. However, a chemical code for simulating products of water radiolysis does not exist in the PHITS package. Here, we developed a chemical simulation code dedicated for the PHITS code, hereafter called PHITS-Chem code, which enables calculating G values of water radiolysis species (OH radical, e, H, HO etc) by electron beams. The estimated G values during 1 s are in agreement with the experimental ones and other simulations. This PHITS-Chem code enables simulating the dynamics in the presence of OH radical scavenger, and is useful for evaluating contributions of direct and indirect effects on DNA damage induction. This code will be included and be available in the future version of PHITS.

Report of summer holiday practical training 2020; Feasibility study on nuclear battery using HTTR core; Feasibility study for nuclear design, 3

Ishitsuka, Etsuo; Mitsui, Wataru*; Yamamoto, Yudai*; Nakagawa, Kyoichi*; Ho, H. Q.; Ishii, Toshiaki; Hamamoto, Shimpei; Nagasumi, Satoru; Takamatsu, Kuniyoshi; Kenzhina, I.*; et al.

JAEA-Technology 2021-016, 16 Pages, 2021/09

JAEA-Technology-2021-016.pdf:1.8MB

As a summer holiday practical training 2020, the feasibility study for nuclear design of a nuclear battery using HTTR core was carried out, and the downsizing of reactor core were studied by the MVP-BURN. As a result, it is clear that a 1.6 m radius reactor core, containing 54 (183 layers) fuel blocks with 20% enrichment of U, and BeO neutron reflector, could operate continuously for 30 years with thermal power of 5 MW. Number of fuel blocks of this compact core is 36% of the HTTR core. As a next step, the further downsizing of core by changing materials of the fuel block will be studied.

A Simplified Cluster Analysis of Electron Track Structure for Estimating Complex DNA Damage Yields

Matsuya, Yusuke; Nakano, Toshiaki*; Kai, Takeshi; Shikazono, Naoya*; Akamatsu, Ken*; Yoshii, Yuji*; Sato, Tatsuhiko

International Journal of Molecular Sciences (Internet), 21(5), p.1701_1 - 1701_13, 2020/03

https://doi.org/10.3390/ijms21051701

Among various DNA damage induced after irradiation, clustered damage composed of at least two vicinal lesions within from 10 to 20 base pairs is recognized as fatal damage to human tissue. Such clustered damage yields have been evaluated by means of computational approaches; however, the simulation validity has not been sufficiently made yet. Meanwhile, the experimental technique to detect clustered DNA damage has been evolved in the recent decades, so both approaches with simulation and experiment get used to be available for investigating clustered damage recently. In this study, we have developed a simple model for estimating clustered damage yield based on the spatial density of ionization and electronic excitation events obtained by the PHITS code, and compared the computational results to the experimental clustered damage coupled with base damage (BD) measured by gel electrophoresis and atomic force microscopy. The computational results agreed well with experimental fractions of clustered damage of strand breaks (SB) and BD, when the yield ratio of BD/SSB is assumed to be 1.3. From the comparison of complex DNA double-strand break coupled with BDs between simulation and experimental data, it was suggested that aggregation degree of the events along electron track reflects the complexity of DNA damage. The resent simulation enables to quantify the type of clustered damage which cannot be measured in in vitro experiment, which succeeded in interpreting the experimental detection efficiency for clustered BD.

Synthesis and characterization of CeO-based simulated fuel containing CsI

Takamatsu, Yuki*; Ishii, Hiroto*; Oishi, Yuji*; Muta, Hiroaki*; Yamanaka, Shinsuke*; Suzuki, Eriko; Nakajima, Kunihisa; Miwa, Shuhei; Osaka, Masahiko; Kurosaki, Ken*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 17(3/4), p.106 - 110, 2018/12

https://doi.org/10.3327/taesj.J17.025

In order to establish the synthesis method of simulated fuel contacting Cesium (Cs) which is required for the evaluation of physical/chemical characteristics in fuel and release behavior of Cs, sintering tests of the cerium dioxide (CeO) based simulated fuels containing Cesium iodide (CsI) are performed by using spark plasma sintering (SPS) method. The sintered CeO pellets with homogeneous distribution of several micro meter of CsI spherical precipitates were successfully obtained by optimizing SPS conditions.

Localization estimation of ionizing radiation-induced abasic sites in DNA in the solid state using fluorescence resonance energy transfer

Akamatsu, Ken; Shikazono, Naoya; Saito, Takeshi*

Radiation Research, 183(1), p.105 - 113, 2015/01

https://doi.org/10.1667/RR13780.1

Clustered DNA damage is considered an important factor in determining the biological consequences of ionizing radiation. We here succeeded in estimating the localization of abasic sites (APs) in DNA irradiated with ionizing radiation using fluorescence resonance energy transfer (FRET) without any involvement of repair enzyme functions. A linearized plasmid was irradiated with Co -rays, the He beam, and the C beam in the solid state. A donor or acceptor fluorescent probe with a nucleophilic O-amino group was used to label APs. The results showed that the C beam likely produced close APs within a track. On the other hand, E values of Co -rays and the He beam were less than those of the C beam, increased with increasing AP density, and were slightly greater than those of randomly distributed APs.

Development of "leaky" liposome triggered by radiation applicable to a drug reservoir and a simple radiation dosimeter

Akamatsu, Ken

Applied Radiation and Isotopes, 74, p.144 - 151, 2013/04

https://doi.org/10.1016/j.apradiso.2013.01.024

Effects of lipid compositions and the content ratios on the membrane permeability of liposome have been investigated using soft X-rays as ionizing radiation (IR) sources. Three-component liposome constituted from an unsaturated phosphatidyl choline (PC), a saturated PC, and cholesterol was selected in a series of the study. As the results, following characteristics of IR-sensitive liposome were discovered: (1) A PC with bis-allylic hydrogen is essential as a component of unsaturated PC., (2) Dilinoleoyl PC (DLOPC) is optimal as a component of unsaturated PC., (3) Either distearoyl PC (DSPC) or dipalmitoyl PC (DPPC) is optimal as a component of saturated PC., (4) Lower dose- rate makes the liposome more IR-sensitive., (5) Lower concentration of liposome makes the liposome more IR-sensitive., (6) There is a region for optimal DLOPC content ratio for the IR-sensitive liposome around 5 20 mol%., and (7) There is a region for optimal cholesterol content ratio for preparing a stable liposome around 30 60 mol%. These fundamental laws for IR-sensitive liposome will contribute to understanding of biomembrane damage by IRs and developing a new-conceptual pharmaceutical available in radiotherapies.

My experience as a consultant for radiation risks; How do we communicate with a client worrying about radiation risks?

Akamatsu, Ken

Hoshasen Seibutsu Kenkyu, 46(2), p.87 - 92, 2011/06

http://ci.nii.ac.jp/naid/40018910985

"Health counseling hot line" concerning the radiation and the radiological consequence was established in the Ministry of Education, Culture, Sports, Science and Technology along with the nuclear disaster due to the East Japan great earthquake. The author and some other staffs of Japan Atomic Energy Agency were consulted by a lot of Japanese clients as a temporary risk-communicator. The concern for nuclear power and the radioactivity and the radiation has spread not only domestically but also all over the world by this disastrous. In this paper, the author discusses how we communicate with a client worrying about radiation risks based on his experiences.

Development of a thermal neutron-sensitive liposome for a novel drug delivery system aiming for radio-chemo-concurrent cancer therapy

Akamatsu, Ken

Radiation Physics and Chemistry, 78(12), p.1179 - 1183, 2009/12

https://doi.org/10.1016/j.radphyschem.2009.07.007

An ionizing radiation-sensitive liposome has been developed aiming for irradiation site-specific controlled release of an anticancer agent from liposomes accumulated at tumor. As the first step of the study, X-ray-sensitive liposome has been constructed, consisting of an unsaturated phosphatidyl choline (PC), a saturated PC, and cholesterol. The radiation sensitivity was estimated by measuring release rate of a fluorophore, calcein, through the lipid bilayer. As a result, the following characteristics of X-ray-sensitive liposomes were discovered: (1) A PC with bis-allylic hydrogen is an essential component of unsaturated PC, (2) Dilinoleoyl PC (DLOPC) is the most favorable component of unsaturated PC, (3) A lower dose rate makes the liposome more X-ray-sensitive. In this presentation, we will discuss radiation chemical mechanism of the ionizing radiation-sensitive liposome, and their pharmaceutical applications for radiation therapy such as boron neutron capture therapy.

Fluorination of PMDA-ODA polyimide using hyperthermal atomic fluorine beams

Tagawa, Masahito*; Yokota, Kumiko*; Maeda, Kenichi*; Yoshigoe, Akitaka; Teraoka, Yuden; Akamatsu, Kensuke*; Nawafune, Hidemi*

Polyimides and Other High-Temperature Polymers; Synthesis, Characterization and Applications, Vol.5, p.249 - 259, 2009/08

Surface fluorination of PMDA-ODA polyimide has been performed by a hyperthermal F beam. The fundamental properties of the F-beam-exposed polyimide surface are reported based on the analytical results by X-ray photoelectron spectroscopy and contact angle measurements. It was observed that CF, CF or CF moieties were formed at the polyimide surfaces depending on the F beam fluences. Advancing contact angles of water can be controlled from 60 to 120 degrees by varying the F beam fluences. Surface roughness analyzed by atomic force microscopy slightly increased with atomic F beam exposures due probably to the formation of volatile products such as CF. This is confirmed by the mass change during F beam exposure by a quartz crystal microbalance.

-ray irradiation of organic extractants for the separation of minor actinides by the tandem accelerator

Sugo, Yumi; Akamatsu, Ken; Hase, Yoshihiro; Taguchi, Mitsumasa; Sasaki, Yuji; Hirota, Koichi; Kimura, Takaumi

JAEA-Conf 2008-012, p.127 - 129, 2009/03

https://jopss.jaea.go.jp/pdfdata/JAEA-Conf-2008-012-1.pdf

no abstracts in English