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Journal Articles

Identification of hydrogen trapping in aluminum alloys $$via$$ muon spin relaxation method and first-principles calculations

Tsuru, Tomohito; Nishimura, Katsuhiko*; Matsuda, Kenji*; Nunomura, Norio*; Namiki, Takahiro*; Lee, S.*; Higemoto, Wataru; Matsuzaki, Teiichiro*; Yamaguchi, Masatake; Ebihara, Kenichi; et al.

Metallurgical and Materials Transactions A, 54(6), p.2374 - 2383, 2023/06

Although hydrogen embrittlement susceptibility of high-strength Al alloys is recognized as a critical issue in the practical use of Al alloys, identifying the hydrogen trapping or distribution has been challenging. In the present study, an effective approach based on experiment and simulation is proposed to explore the potential trap sites in Al alloys. Zero-field muon spin relaxation experiments were carried out for Al-0.5%Mg, Al-0.2%Cu, Al-0.15%Ti, Al-0.011%Ti, Al-0.28%V, and Al-0.015%V (at.%) in the temperature range from 5 to 300 K. The temperature variations of the dipole field widths have revealed three peaks for Al-0.5%Mg, four peaks for Al-0.2%Cu, three peaks for Al-0.011%Ti and Al-0.015%V. Atomic configurations of the muon trapping sites corresponding to the observed $$Delta$$ peaks are well assigned using the first-principles calculations for the trap energies of hydrogen around a solute and solute-vacancy pair. The extracted linear relationship between the muon $$Delta$$ peak temperature and the trap energy enables us to explore the potential alloying elements and their complex that have strong binding energies with hydrogen in Al alloys.

Journal Articles

$$^{60}$$Fe and $$^{244}$$Pu deposited on Earth constrain the r-process yields of recent nearby supernovae

Wallner, A.*; Froehlich, M. B.*; Hotchkis, M. A. C.*; Kinoshita, N.*; Paul, M.*; Martschini, M.*; Pavetich, S.*; Tims, S. G.*; Kivel, N.*; Schumann, D.*; et al.

Science, 372(6543), p.742 - 745, 2021/05

 Times Cited Count:31 Percentile:96.53(Multidisciplinary Sciences)

Half of the chemical elements heavier than iron are produced by the rapid neutron capture process (r-process). The sites and yields of this process are disputed, with candidates including some types of supernovae (SNe) and mergers of neutron stars. We search for two isotopic signatures in a sample of Pacific Ocean crust-iron-60 ($$^{60}$$Fe) (half-life, 2.6 million years), which is predominantly produced in massive stars and ejected in supernova explosions, and $$^{244}$$Pu (half-life, 80.6 million years), which is produced solely in r-process events. We detect two distinct influxes of $$^{60}$$Fe to Earth in the last 10 million years and accompanying lower quantities of $$^{244}$$Pu. The $$^{244}$$Pu/$$^{60}$$Fe influx ratios are similar for both events. The $$^{244}$$Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, which implies some contribution from other sources.

JAEA Reports

Practical guide on soil sampling, treatment, and carbon isotope analysis for carbon cycle studies

Koarashi, Jun; Atarashi-Andoh, Mariko; Nagano, Hirohiko*; Sugiharto, U.*; Saengkorakot, C.*; Suzuki, Takashi; Kokubu, Yoko; Fujita, Natsuko; Kinoshita, Naoki; Nagai, Haruyasu; et al.

JAEA-Technology 2020-012, 53 Pages, 2020/10

JAEA-Technology-2020-012.pdf:3.71MB

There is growing concern that recent rapid changes in climate and environment could have a significant influence on carbon cycling in terrestrial ecosystems (especially forest ecosystems) and could consequently lead to a positive feedback for global warming. The magnitude and timing of this feedback remain highly uncertain largely due to a lack of quantitative understanding of the dynamics of organic carbon stored in soils and its responses to changes in climate and environment. The tracing of radiocarbon (natural and bomb-derived $$^{14}$$C) and stable carbon ($$^{13}$$C) isotopes through terrestrial ecosystems can be a powerful tool for studying soil organic carbon (SOC) dynamics. The primary aim of this guide is to promote the use of isotope-based approaches to improve our understanding of the carbon cycling in soils, particularly in the Asian region. The guide covers practical methods of soil sampling; treatment and fractionation of soil samples; preparation of soil samples for $$^{13}$$C (and stable nitrogen isotope, $$^{15}$$N) and $$^{14}$$C analyses; and $$^{13}$$C, $$^{15}$$N, and $$^{14}$$C measurements by the use of isotope ratio mass spectrometry and accelerator mass spectrometry (AMS). The guide briefly introduces ways to report $$^{14}$$C data, which are frequently used for soil carbon cycling studies. The guide also reports results of a case study conducted in a Japanese forest ecosystem, as a practical application of the use of isotope-based approaches. This guide is mainly intended for researchers who are interested but are not experienced in this research field. The guide will hopefully encourage readers to participate in soil carbon cycling studies, including field works, laboratory experiments, isotope analyses, and discussions with great interest.

Journal Articles

Pre- and post-accident $$^{14}$$C activities in tree rings near the Fukushima Dai-ichi Nuclear Power Plant

Matsunaka, Tetsuya*; Sasa, Kimikazu*; Takahashi, Tsutomu*; Matsumura, Masumi*; Satou, Yukihiko; Shen, H.*; Sueki, Keisuke*; Matsuzaki, Hiroyuki*

Radiocarbon, 61(6), p.1633 - 1642, 2019/12

 Times Cited Count:2 Percentile:11.91(Geochemistry & Geophysics)

Journal Articles

Grain size dependence of meteoric $$^{10}$$Be concentrations in bed-sediments of Ado and Yasu rivers flowing into Lake Biwa

Fujisawa, Jumpei*; Minami, Masayo*; Kokubu, Yoko; Matsuzaki, Hiroyuki*

JAEA-Conf 2018-002, p.91 - 94, 2019/02

Beryllium-10 ($$^{10}$$Be) of a cosmogenic nuclide precipitates in forms of BeO and Be(OH)$$_{2}$$ attaching with aerosol on the Earth surface. It is accumulated on the sea- and lake-bottoms. Recently, the meteoric $$^{10}$$Be is attracting attention as a powerful tool for investigating the past climate change, because it is affected by the earth- and lorcal- cyclical changes of materials such as atmosphere and water circulation. The $$^{10}$$Be exists mostly as hydroxide at pH $$>$$5, and is easy to adhere to soil and mineral surface. Therefore, $$^{10}$$Be concentration in sediment could be influenced by its grain size composition because fine-grained sediment has a big surface area per unit mass. The purpose of this study is to reveal the relationship between $$^{10}$$Be concentrations and the grain-size of river sediments. The samples used were bottom-sediments of 18 rivers flowing into Lake Biwa, Japan. The sediments were sieved to 5 fractions and analyzed each for $$^{10}$$Be concentration by JAEA-AMS-TONO.

Journal Articles

Age and speciation of iodine in groundwater and mudstones of the Horonobe area, Hokkaido, Japan; Implications for the origin and migration of iodine during basin evolution

Togo, Yoko*; Takahashi, Yoshio*; Amano, Yuki; Matsuzaki, Hiroyuki*; Suzuki, Yohei*; Terada, Yasuko*; Muramatsu, Yasuyuki*; Ito, Kazumasa*; Iwatsuki, Teruki

Geochimica et Cosmochimica Acta, 191, p.165 - 186, 2016/10

 Times Cited Count:25 Percentile:73.46(Geochemistry & Geophysics)

Iodine distribution, speciation, and isotope ratio ($$^{129}$$I/$$^{127}$$I) in both rock and groundwater phases were determined to investigate long-term migration of iodine in diatomaceous and siliceous shale. It was suggested that I$$^{-}$$ is released to the ground water during the progress of the maturation of organic matter. Dissociated I$$^{-}$$ could move toward the surface because of the upward water flow driven by the compaction during burial diagenetic process. Thus, iodine rich brine is created by integration of iodine released from underlying formations. Because of low affinity of I$$^{-}$$ to solid phase, released I$$^{-}$$ remains in solution phase, and the concentration of the iodine in the solution has been possibly increasing during sedimentation history.

Journal Articles

Growth of single-phase nanostructured Er$$_2$$O$$_3$$ thin films on Si (100) by ion beam sputter deposition

Mao, W.*; Fujita, Masaya*; Chikada, Takumi*; Yamaguchi, Kenji; Suzuki, Akihiro*; Terai, Takayuki*; Matsuzaki, Hiroyuki*

Surface & Coatings Technology, 283, p.241 - 246, 2015/12

 Times Cited Count:3 Percentile:13.97(Materials Science, Coatings & Films)

Single-phase nanocrystalline thin films of Er$$_2$$O$$_3$$ (440) has been first prepared using Si (100) substrates by ion beam sputter deposition at 973 K at a pressure of $$<$$ 10$$^{-5}$$ Pa and $${it in}$$-$${it situ}$$ annealing at 1023 K at a pressure of $$approx$$ 10$$^{-7}$$ Pa. Er silicides formed during the deposition are eliminated via the annealing, which results in the single phase and the smooth surface of the Er$$_2$$O$$_3$$ thin films. The epitaxial relationship between Si (100) and Er$$_2$$O$$_3$$ (110) is clarified by X-ray diffraction and reflection high energy electron diffraction.

Journal Articles

A Study of new preparation method for AMS targets

Katayama, Atsushi; Kameo, Yutaka; Nakashima, Mikio; Matsuzaki, Hiroyuki*

Dai-10-Kai AMS Shimpojiumu Hokokushu, p.234 - 237, 2008/00

The determination of $$^{129}$$I by accelerator mass spectrometry (AMS) has generally been used measurement targets from AgI precipitation. For more sensitive determination of $$^{129}$$I, it is necessary to reduce the quantity of iodine carrier for precipitation. But, more than 1mg is the amount of carrier stable iodine needed at present to make a reliable sample treatment and AMS determination. In this study, we examined the basics of procedures of the direct measurement target that used adsorption reaction of the molecular iodine to the metal silver surface in substitution for precipitation. Using this procedure, we have prepared measurement targets with a carrier from 1 to 0.2 mg iodine.

Journal Articles

Development of electrochemical hydrogen pump under vacuum condition for a compact tritium gas cycling system

Kato, Mineo; Ito, Takeshi*; Sugai, Hiroyuki; Kawamura, Yoshinori; Hayashi, Takumi; Nishi, Masataka; Tanase, Masakazu; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; Nagamine, Kanetada*

Fusion Science and Technology, 41(3), p.859 - 862, 2002/05

JAERI has a plane to develop a compact tritium gas recycling system for fusion research. This system is also very attractive for the muon-catalyzed fusion ($$mu$$CF) research at RIKEN-RAL Muon Facility in UK. For the research, JAERI has produced high purity tritium gas of 1,500 Ci and transported it to the Facility. In the $$mu$$CF experiments, the tritium gas was diluted by the deuterium in an optional concentration and the used tritium gas was carried back by the tritium transport container developed to JAERI. If it is possible to recycle the diluted tritium gas, i.e., the used tritium gas is enriched in the experimental site, the $$mu$$CF experiments should be conducted efficiently. rom the above point of view, in this paper, we propose the compact tritium gas recycling system based on the gas chromatography that has already developed in JAERI and a proton conductor.

Journal Articles

He accumulation effect in solid and liquid D-T mixture

*; Nagamine, Kanetada*; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; *; Sakamoto, Shinichi*; *; Tanase, Masakazu; Kato, Mineo; Kurosawa, Kiyoyuki; et al.

Hyperfine Interactions, 118(1-4), p.213 - 215, 1999/00

no abstracts in English

Journal Articles

Muon catalyzed fusion and muon to $$^{3}$$He transfer in solid T$$_{2}$$ studied by X-ray and neutron detection

Matsuzaki, Teiichiro*; Nagamine, Kanetada*; Ishida, Katsuhiko*; *; *; Tanase, Masakazu; Kato, Mineo; Kurosawa, Kiyoyuki; Hashimoto, Masashi; Sugai, Hiroyuki; et al.

Hyperfine Interactions, 118(1-4), p.229 - 234, 1999/00

no abstracts in English

Journal Articles

Measurement of X-rays from muon to $$alpha$$ sticking and fusion neutrons in solid/liquid D-T mixtures of high tritium concentration

Ishida, Katsuhiko*; Nagamine, Kanetada*; Matsuzaki, Teiichiro*; *; *; Sakamoto, Shinichi*; *; Tanase, Masakazu; Kato, Mineo; Kurosawa, Kiyoyuki; et al.

Hyperfine Interactions, 118(1-4), p.203 - 208, 1999/00

no abstracts in English

Journal Articles

High purity tritium gas supplied by JAERI for muon catalyzed fusion research at RIKEN-RAL muon facilty

Kato, Mineo; Kurosawa, Kiyoyuki; Sugai, Hiroyuki; Tanase, Masakazu; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; Nagamine, Kanetada*

KEK Proceedings 99-11, p.113 - 127, 1999/00

no abstracts in English

Journal Articles

Measurement of the K$$_{beta}$$/K$$_{alpha}$$ ratio of muon to $$alpha$$ sticking X-rays in muon catalyzed d-t fusion at RIKEN-RAL muon facility

*; Nagamine, Kanetada*; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; *; Sakamoto, Shinichi*; *; Tanase, Masakazu; Kato, Mineo; Kurosawa, Kiyoyuki; et al.

Hyperfine Interactions, 118(1-4), p.209 - 212, 1998/00

no abstracts in English

Journal Articles

Preparation of pure tritium for a liquid D$$_{2}$$/T$$_{2}$$ target of muon-catalyzed fusion experiments

Kudo, Hiroshi; Fujie, Makoto; Tanase, Masakazu; Kato, Mineo; Kurosawa, Kiyoyuki; Sugai, Hiroyuki; Umezawa, Hirokazu; Matsuzaki, Teiichiro*; Nagamine, Kanetada*

Applied Radiation and Isotopes, 43(5), p.577 - 583, 1992/00

no abstracts in English

Journal Articles

X-ray observation of $$alpha$$-sticking phenomena in muon catalyzed fusion for a high density D-T mixture with 30% tritium concentration

Nagamine, Kanetada*; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; *; *; *; Miyake, Yasuhiro*; *; *; *; et al.

Muon Catal. Fusion, 5-6, p.289 - 295, 1991/00

no abstracts in English

Oral presentation

A Study of new preparation method for AMS targets; Utilizing an adsorption reaction for iodine-129 sample preparation

Katayama, Atsushi; Ishimori, Kenichiro; Kameo, Yutaka; Suzuki, Takashi; Matsuzaki, Hiroyuki*; Kimura, Kenichi*; Kinno, Masaharu*; Amano, Hikaru; Nakashima, Mikio

no journal, , 

no abstracts in English

Oral presentation

A Study of sample preparation for $$^{129}$$I AMS analysis; Application to radioactive waste and irradiated rocks samples

Katayama, Atsushi; Ishimori, Kenichiro; Kameo, Yutaka; Suzuki, Takashi; Kinno, Masaharu*; Kimura, Kenichi*; Matsuzaki, Hiroyuki*; Nakashima, Mikio

no journal, , 

no abstracts in English

Oral presentation

Migration of iodine in diatomaceous and siliceous shales in Horonobe, Hokkaido

Shimamoto, Yoko*; Takahashi, Yoshio*; Amano, Yuki; Matsuzaki, Hiroyuki*; Muramatsu, Yasuyuki*; Iwatsuki, Teruki

no journal, , 

Study of migration of iodine in the subsurface environment is important for natural analogue of HLW. The vertical distribution of iodine concentration, the type of iodine, and isotope were analyzed for the sample of groundwater and sedimentary rocks of the Horonobe area. The results showed that iodine ion were existed in the groundwater, and the mixed iodine with organic and inorganic type were existed in the rock samples.

Oral presentation

Migration of iodine in diatomaceous and siliceous shales based on speciation and $$^{129}$$I/$$^{127}$$I analysis $$^{129}$$I/$$^{127}$$I

Shimamoto, Yoko*; Takahashi, Yoshio*; Amano, Yuki; Matsuzaki, Hiroyuki*; Muramatsu, Yasuyuki*; Iwatsuki, Teruki

no journal, , 

We determined iodine distribution, speciation, and isotope ratio ($$^{129}$$I/$$^{127}$$I), to investigate long-term migration of iodine in diatomaceous and siliceous shales, using core and groundwater samples collected at JAEA Horonobe underground research center. Iodine in core samples dramatically decreased near the boundary between Wk and Kt Formations. Iodine exists as I$$^{-}$$ in groundwater, while that in shales is a mixture of organic and inorganic I. Iodine isotope ratio ($$^{129}$$I/$$^{127}$$I) is slightly higher in siliceous shale compared with that of groundwater. According to these results, migration of iodine in this area can be expected as follows; (1) iodine accumulated as organic iodine in siliceous sediment. (2) Iodine was released from Wk Formation during diagenetic process as I$$^{-}$$ to form iodine-rich groundwater. (3) Iodine-rich groundwater was distributed to Wk and Kt Formations due to the compaction of the layers. (4) Both iodine and chlorine were diluted by freshwater from the surface.

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