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Journal Articles

Transport model comparison studies of intermediate-energy heavy-ion collisions

Walter, H.*; Colonna, M.*; Cozma, D.*; Danielewicz, P.*; Ko, C. M.*; Kumar, R.*; Ono, Akira*; Tsang, M. Y. B*; Xu, J.*; Zhang, Y.-X.*; et al.

Progress in Particle and Nuclear Physics, 125, p.103962_1 - 103962_90, 2022/07

Transport models are the main method to obtain physics information on the nuclear equation of state and in-medium properties of particles from low to relativistic-energy heavy-ion collisions. The Transport Model Evaluation Project (TMEP) has been pursued to test the robustness of transport model predictions to reach consistent conclusions from the same type of physical model. To this end, calculations under controlled conditions of physical input and set-up were performed by the various participating codes. These included both calculations of nuclear matter in a periodic box, which test individual ingredients of a transport code, and calculations of complete collisions of heavy ions. Over the years, five studies were performed within this project. They show, on one hand, that in box calculations the differences between the codes can be well understood and a convergence of the results can be reached. These studies also highlight the systematic differences between the two families of transport codes, known under the names of Boltzmann-Uehling-Uhlenbeck (BUU) and Quantum Molecular Dynamics (QMD) type codes. On the other hand, there still exist substantial differences when these codes are applied to real heavy-ion collisions. The results of transport simulations of heavy-ion collisions will have more significance if codes demonstrate that they can verify benchmark calculations such as the ones studied in these evaluations.

JAEA Reports

Stabilization treatment of nuclear fuel material contained with organic matter

Senzaki, Tatsuya; Arai, Yoichi; Yano, Kimihiko; Sato, Daisuke; Tada, Kohei; Ogi, Hiromichi*; Kawanobe, Takayuki*; Ono, Shimpei; Nakamura, Masahiro; Kitawaki, Shinichi; et al.

JAEA-Testing 2022-001, 28 Pages, 2022/05

JAEA-Testing-2022-001.pdf:2.33MB

In preparation for the decommissioning of Laboratory B of the Nuclear Fuel Cycle Engineering Laboratory, the nuclear fuel material that had been stored in the glove box for a long time was moved to the Chemical Processing Facility (CPF). This nuclear fuel material was stored with sealed by a polyvinyl chloride (PVC) bag in the storage. Since it was confirmed that the PVC bag swelled during storage, it seems that any gas was generated by radiolysis of the some components contained in the nuclear fuel material. In order to avoid breakage of the PVC bag and keep it safety for long time, we began the study on the stabilization treatment of the nuclear fuel material. First, in order to clarify the properties of nuclear fuel material, radioactivity analysis, component analysis, and thermal analysis were carried out. From the results of thermal analysis, the existence of organic matter was clarified. Then, ion exchange resin with similar thermal characteristics was selected and the thermal decomposition conditions were investigated. From the results of these analyzes and examinations, the conditions for thermal decomposition of the nuclear fuel material contained with organic matter was established. Performing a heat treatment of a small amount of nuclear fuel material in order to confirm the safety, after which the treatment amount was scaled up. It was confirmed by the weight change after the heat treatment that the nuclear fuel material contained with organic matter was completely decomposed.

Journal Articles

Precise magnetization measurements down to 500 mK using a miniature $$^3$$He cryostat and a closed-cycle $$^3$$He gas handling system installed in a SQUID magnetometer without continuous-cooling functionality

Shimamura, Kazutoshi*; Wajima, Hiroki*; Makino, Hayato*; Abe, Satoshi*; Haga, Yoshinori; Sato, Yoshiaki*; Kawae, Tatsuya*; Yoshida, Yasuo*

Japanese Journal of Applied Physics, 61(5), p.056502_1 - 056502_7, 2022/05

Journal Articles

Benchmark study of particle and heavy-ion transport code system using shielding integral benchmark archive and database for accelerator-shielding experiments

Iwamoto, Yosuke; Hashimoto, Shintaro; Sato, Tatsuhiko; Matsuda, Norihiro; Kunieda, Satoshi; $c{C}$elik, Y.*; Furutachi, Naoya*; Niita, Koji*

Journal of Nuclear Science and Technology, 59(5), p.665 - 675, 2022/05

A benchmark study of PHITS3.24 has been conducted using neutron-shielding experiments listed in the Shielding Integral Benchmark Archive and Database. Five neutron sources were selected, which are generated from (1) 43- and 68-MeV proton-induced reaction on a thin lithium target, (2) 52-MeV proton-induced reaction on a thick graphite target, (3) 590-MeV proton-induced reaction on a thick lead target, (4) 500-MeV proton-induced reaction on a thick tungsten target, and (5) 800-MeV proton-induced reaction on a thick tantalum target. For all cases, overall agreements in the results are satisfactory when using the JENDL-4.0/HE to simulate neutron- and proton-induced reactions up to 200 MeV. However, discrepancies using PHITS default settings are observed in the results. For an accurate neutron-shielding design for accelerator facilities, using JENDL-4.0/HE in the particle and heavy-ion transport code system calculation is favorable.

Journal Articles

Permeability change in macro-fractured granite using water including clay

Nara, Yoshitaka*; Kato, Masaji*; Sato, Tsutomu*; Kono, Masanori*; Sato, Toshinori

Journal of MMIJ, 138(4), p.44 - 50, 2022/04

It is important to understand the long-term migration of radionuclides when considering rock engineering projects such as the geological disposal of radioactive waste. The network of fractures and pores in a rock mass plays a major role in fluid migration as it provides a pathway for fluid flow. The geometry of a network can change due to fracture sealing by some fine-grained materials over long-term periods. In the present study, we use a macro-fractured granite sample to investigate the change of permeability that occurs under the flow of water that includes two different amounts of clay. Findings showed that clay accumulated in a fracture and that the permeability (hydraulic conductivity) of the granite sample decreased over time, which was greater in for the higher clay content. We concluded that the accumulation of clay minerals in the fracture decreased the permeability of the rock. Furthermore, we consider that the filling and closure of fractures in rock is possible under the flow of groundwater that includes clay minerals.

Journal Articles

Abrupt change in electronic states under pressure in new compound EuPt$$_3$$Al$$_5$$

Koizumi, Takatsugu*; Honda, Fuminori*; Sato, Yoshiki*; Li, D.*; Aoki, Dai*; Haga, Yoshinori; Gochi, Jun*; Nagasaki, Shoko*; Uwatoko, Yoshiya*; Kaneko, Yoshio*; et al.

Journal of the Physical Society of Japan, 91(4), p.043704_1 - 043704_5, 2022/04

Journal Articles

$$^{rm 206,207,208,nat}$$Pb(p,x)$$^{194}$$Hg and $$^{209}$$Bi(p,x)$$^{194}$$Hg excitation functions in the energy range 0.04 - 2.6 GeV

Titarenko, Yu. E.*; Batyaev, V. F.*; Pavlov, K. V.*; Titarenko, A. Yu.*; Malinovskiy, S. V.*; Rogov, V. I.*; Zhivun, V. M.*; Kulevoy, T. V.*; Chauzova, M. V.*; Khalikov, R. S.*; et al.

Nuclear Instruments and Methods in Physics Research A, 1026, p.166151_1 - 166151_9, 2022/03

The paper presents the $$^{194}$$Hg production cross-sections measured by the direct gamma-spectrometry technique in the samples of lead enriched with isotopes 206, 207 and 208, as well as in the samples of natural lead and bismuth, irradiated by protons of 11 energies in the range from 0.04 to 2.6 GeV. The obtained experimental results are compared with the previous measurements, with the TENDL-2019 data-library evaluations and the simulated data by means of the high-energy transport codes MCNP6.1 (CEM03.03), PHITS (INCL4.6/GEM), Geant4 (INCL++/ABLA) and the nuclear reaction code TALYS.

Journal Articles

Environmental effects on layer-dependent dynamics of Dirac fermions in quasicrystalline bilayer graphene

Zhao, Y.*; Suzuki, T.*; Iimori, T.*; Kim, H.-W.*; Ahn, J. R.*; Horio, Masafumi*; Sato, Yusuke*; Fukaya, Yuki; Kanai, T.*; Okazaki, K.*; et al.

Physical Review B, 105(11), p.115304_1 - 115304_8, 2022/03

no abstracts in English

Journal Articles

LIVE-J1 experiment on debris melting behavior toward understanding late in-vessel accident progression of the Fukushima Daiichi Nuclear Power Station

Madokoro, Hiroshi; Yamashita, Takuya; Sato, Ikken; Gaus-Liu, X.*; Cron, T.*; Fluhrer, B.*; St$"a$ngle, R.*; Wenz, T.*; Vervoortz, M.*; Mizokami, Shinya

Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 16 Pages, 2022/03

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2020

Nakada, Akira; Nakano, Masanao; Kanai, Katsuta; Seya, Natsumi; Nishimura, Shusaku; Nemoto, Masashi; Tobita, Keiji; Futagawa, Kazuo; Yamada, Ryohei; Uchiyama, Rei; et al.

JAEA-Review 2021-062, 163 Pages, 2022/02

JAEA-Review-2021-062.pdf:2.87MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2020 to March 2021. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.

JAEA Reports

Improvement of the Simplified Decommissioning Cost Estimation Code for Nuclear Facilities (DECOST)

Takahashi, Nobuo; Kubota, Shintaro; Takiya, Hiroaki; Sakaba, Ryosuke*; Sato, Koichi; Shichi, Ryo

JAEA-Testing 2021-002, 106 Pages, 2022/01

JAEA-Testing-2021-002.pdf:2.08MB

The Japan Atomic Energy Agency has various nuclear facilities such as reactor facilities and reprocessing facilities. Some aged facilities will be decommissioned after their original functions ended, and it is necessary to evaluate their decommissioning cost to formulate the initial decommissioning plans and the final decommissioning plans. We have developed an evaluation method called DECOST that can efficiently calculate the decommissioning cost in a short time based on factors such as features and similarity of the facilities and dismantling methods. The decommissioning of nuclear facilities has been implemented and new achievements and findings have been reported since the development of DECOST. These findings were reflected in DECOST. In consideration of the needs of DECOST users, DECOST has been improved so that the cost of dismantling the facility can be divided into the cost of releasing the controlled area and the cost of dismantling the facility building after the release of the controlled area. This report shows the improvement of DECOST, the concept of resetting the evaluation coefficient used in the cost evaluation formula, and the validity of the evaluation coefficient after resetting. In addition, the evaluation procedure of the improved DECOST is described, since the evaluation items and evaluation contents were partially changed due to the improvement.

JAEA Reports

Stabilization treatment of Pu-bearing organic materials

Morishita, Kazuki; Sato, Takumi; Onishi, Takashi; Seki, Takayuki*; Sekine, Shinichi*; Okitsu, Yuichi*

JAEA-Technology 2021-024, 27 Pages, 2021/10

JAEA-Technology-2021-024.pdf:2.41MB

In the case of Plutonium (Pu)-bearing organic materials, organic materials are decomposed by alpha rays emitted mainly from Pu to generate hydrogen gas and other substances. Therefore, to safely store Pu-bearing organic materials for an extended period of time, organic materials must be eliminated. In addition, carbide and nitride fuels must be converted into oxides for safe storage in order to prevent the exothermal reaction of these fuels with oxygen/moisture in air. A survey of the literature on the stabilization treatment of Pu-bearing organic materials confirmed that organic materials can be decomposed and removed by heating at 950 $$^{circ}$$C (1223.15 K) or greater in air. Furthermore, based on the calculated thermodynamic parameters of oxidation reaction of carbide and nitride fuels in air, it was estimated that these fuels would be oxidized in air at 950 $$^{circ}$$C because the equilibrium oxygen partial pressure in the oxidation reaction at 950 $$^{circ}$$C was lower than 2.1$$times$$10$$^{4}$$ Pa (oxygen partial pressure in air). Therefore, it was decided to stabilize Pu-bearing organic materials by heating at 950 $$^{circ}$$C in air to remove the organic materials and oxidize the carbide and nitride fuels. As a mock-up test to remove the organic materials, thin sheets of epoxy resin were heated in air. The changes in appearance and weight before and after heating in air showed that organic materials can be removed. After the mock-up test, Pu-bearing organic materials were also stabilized by heating in the similar condition.

Journal Articles

Implementation of simplified stochastic microdosimetric kinetic models into PHITS for application to radiation treatment planning

Sato, Tatsuhiko; Hashimoto, Shintaro; Inaniwa, Taku*; Takada, Kenta*; Kumada, Hiroaki*

International Journal of Radiation Biology, 97(10), p.1450 - 1460, 2021/10

 Times Cited Count:0 Percentile:0.01(Biology)

The stochastic microdosimetric kinetic (SMK) model is one of the most sophisticated and precise models used in the estimation of the relative biological effectiveness of carbon-ion radiotherapy (CRT) and boron neutron capture therapy (BNCT). Through the introduction of Taylor expansion (TE) or fast Fourier transform (FFT), we developed two simplified SMK models and implemented them into the Particle and Heavy Ion Transport code System (PHITS). This study enables the instantaneous calculation of the equieffective dose for CRT and BNCT, considering their cellular-scale dose heterogeneities. Treatment-planning systems that use the improved PHITS as a dose-calculation engine are under development.

Journal Articles

Design for detecting recycling muon after muon-catalyzed fusion reaction in solid hydrogen isotope target

Okutsu, Kenichi*; Yamashita, Takuma*; Kino, Yasushi*; Nakashima, Ryota*; Miyashita, Konan*; Yasuda, Kazuhiro*; Okada, Shinji*; Sato, Motoyasu*; Oka, Toshitaka; Kawamura, Naritoshi*; et al.

Fusion Engineering and Design, 170, p.112712_1 - 112712_4, 2021/09

A muonic molecule which consists of two hydrogen isotope nuclei (deuteron (d) or tritium (t)) and a muon decays immediately via nuclear fusion and the muon will be released as a recycling muon, and start to find another hydrogen isotope nucleus. The reaction cycle continues until the muon ends up its lifetime of 2.2 $$mu$$s. Since the muon does not participate in the nuclear reaction, the reaction is so called a muon catalyzed fusion ($$mu$$CF). The recycling muon has a particular kinetic energy (KE) of the muon molecular orbital when the nuclear reaction occurs. Since the KE is based on the unified atom limit where distance between two nuclei is zero. A precise few-body calculation estimating KE distribution (KED) is also in progress, which could be compared with the experimental results. In the present work, we observed recycling muons after $$mu$$CF reaction.

Journal Articles

Technical Note: Validation of a material assignment method for a retrospective study of carbon-ion radiotherapy using Monte Carlo simulation

Chang, W.*; Koba, Yusuke*; Furuta, Takuya; Yonai, Shunsuke*; Hashimoto, Shintaro; Matsumoto, Shinnosuke*; Sato, Tatsuhiko

Journal of Radiation Research (Internet), 62(5), p.846 - 855, 2021/09

With the aim of developing a revaluation tool of treatment plan in carbon-ion radiotherapy using Monte Carlo (MC) simulation, we propose two methods; one is dedicated to identify realistic-tissue materials from a CT image with satisfying the well-calibrated relationship between CT numbers and stopping power ratio (SPR) provided by TPS, and the other is to estimate dose to water considering the particle- and energy-dependent SPR between realistic tissue materials and water. We validated these proposed methods by computing depth dose distribution in homogeneous and heterogeneous phantoms composed of human tissue materials and water irradiated by a 400 MeV/u carbon beam with 8 cm SOBP using a MC simulation code PHITS and comparing with results of conventional treatment planning system (TPS). Our result suggested that use of water as a surrogate of real tissue materials, which is adopted in conventional TPS, is inadequate for dose estimation from secondary particles because their production rates cannot be scaled by SPR of the primary particle in water. We therefore concluded that the proposed methods can play important roles in the reevaluation of the treatment plans in carbon-ion radiotherapy.

Journal Articles

Time evolution calculation of muon catalysed fusion; Emission of recycling muons from a two-layer hydrogen film

Yamashita, Takuma*; Okutsu, Kenichi*; Kino, Yasushi*; Nakashima, Ryota*; Miyashita, Konan*; Yasuda, Kazuhiro*; Okada, Shinji*; Sato, Motoyasu*; Oka, Toshitaka; Kawamura, Naritoshi*; et al.

Fusion Engineering and Design, 169, p.112580_1 - 112580_5, 2021/08

A muon ($$mu$$) having 207 times larger mass of electron and the same charge as the electron has been known to catalyze a nuclear fusion between deuteron (d) and triton (t). These two nuclei are bound by $$mu$$ and form a muonic hydrogen molecular ion, dt$$mu$$. Due to the short inter-nuclear distance of dt$$mu$$, the nuclear fusion, d +t$$rightarrow alpha$$ + n + 17.6 MeV, occurs inside the molecule. This reaction is called muon catalyzed fusion ($$mu$$CF). Recently, the interest on $$mu$$CF is renewed from the viewpoint of applications, such as a source of high-resolution muon beam and mono-energetic neutron beam. In this work, we report a time evolution calculation of $$mu$$CF in a two-layered hydrogen isotope target.

Journal Articles

Rabi-oscillation spectroscopy of the hyperfine structure of muonium atoms

Nishimura, Shoichiro*; Torii, Hiroyuki*; Fukao, Yoshinori*; Ito, Takashi; Iwasaki, Masahiko*; Kanda, Sotaro*; Kawagoe, Kiyotomo*; Kawall, D.*; Kawamura, Naritoshi*; Kurosawa, Noriyuki*; et al.

Physical Review A, 104(2), p.L020801_1 - L020801_6, 2021/08

 Times Cited Count:0 Percentile:0.01(Optics)

Journal Articles

Meteorological aspects of gamma-ray glows in winter thunderstorms

Wada, Yuki*; Enoto, Teruaki*; Kubo, Mamoru*; Nakazawa, Kazuhiro*; Shinoda, Taro*; Yonetoku, Daisuke*; Sawano, Tatsuya*; Yuasa, Takayuki*; Ushio, Tomoo*; Sato, Yosuke*; et al.

Geophysical Research Letters, 48(7), 11 Pages, 2021/04

 Times Cited Count:1 Percentile:0(Geosciences, Multidisciplinary)

During three winter seasons from November 2016 to March 2019, 11 gamma-ray glows were detected at a single observation site of our ground-based gamma-ray monitoring network in Kanazawa, Japan. These events are analyzed with observations of an X-band radar network, a ceilometer, a disdrometer, and a weather monitor. All the detected glows were connected to convective high-reflectivity regions of more than 35 dBZ, developed up to an altitude of $$>$$2 km. They were also accompanied by heavy precipitation of graupels. Therefore, graupels in the lower layer of thunderclouds that correspond to high-reflectivity regions can form strong electric fields producing gamma-ray glows. Also, these events are compared with a limited sample of nondetection cases, but no significant differences in meteorological conditions were found between detection and nondetection cases in the present study.

Journal Articles

Evaluation of core material energy change during the in-vessel phase of Fukushima Daiichi Unit 3 based on observed pressure data utilizing GOTHIC code analysis

Sato, Ikken; Arai, Yuta*; Yoshikawa, Shinji

Journal of Nuclear Science and Technology, 58(4), p.434 - 460, 2021/04

 Times Cited Count:2 Percentile:94.32(Nuclear Science & Technology)

Journal Articles

Oxygen enhancement ratios of cancer cells after exposure to intensity modulated X-ray fields; DNA damage and cell survival

Matsuya, Yusuke; McMahon, S. J.*; Butterworth, K. T.*; Naijo, Shingo*; Nara, Isshi*; Yachi, Yoshie*; Saga, Ryo*; Ishikawa, Masayori*; Sato, Tatsuhiko; Date, Hiroyuki*; et al.

Physics in Medicine & Biology, 66(7), p.075014_1 - 075014_11, 2021/04

 Times Cited Count:0 Percentile:0.01(Engineering, Biomedical)

Hypoxic cancer cells within solid tumours show radio-resistance, leading to malignant progression in fractionated radiotherapy. When prescribing dose to tumours under heterogeneous oxygen pressure with intensity-modulated radiation fields, intercellular signalling could have an impact on radiosensitivity between in-field and out-of-field cells. However, the impact of hypoxia on radio-sensitivity under modulated radiation intensity remains uncertain. In this study, we investigate the impact of hypoxia on in-field and out-of-field radio-sensitivities using two types of cancer cells. These in vitro measurements indicate that hypoxia apparently impacts out-of-field cells, although the OER values in out-of-field cells were smaller compared to those for in-field and uniformly irradiated cells. These decreased radio-sensitivities of out-of-field cells were shown as a consistent tendency for both DSB and cell death endpoints, suggesting that radiation-induced intercellular communication is of importance in treatment planning with intensity-modulated radiotherapy.

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