A Review and interpretation of iodine-129 in Earth's surface layers; Towards evaluating the long-term stability of geological environments

Mitsuguchi, Takehiro; Okabe, Nobuaki*; Kokubu, Yoko; Matsuzaki, Hiroyuki*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 31(2), p.96 - 110, 2024/12

https://doi.org/10.3327/jnuce.31.2_96

Geological disposal of high-level radioactive waste requires not only selecting sites appropriate for the waste repository, where its isolation ability would not be damaged by natural phenomena for several tens of thousands of years, but also rationally constructing the disposal system depending on site-specific geological environments and their anticipated long-term variability. Recently, elemental/isotopic compositions of underground fluids (deep groundwaters, hot/cold spring waters, brines associated with oil and natural gas reservoirs, and so on) in Japan have been studied for evaluating the long-term stability of the geological environments of this country. Iodine and its radioactive isotope I (half-life = 15.7 million years) are included in the subjects of the study. The current review paper provides overviews of (i) the iodine content and iodine-129/127 ratio (I/I ratio) of various materials in Earth's surface layers, (ii) relevant sample pretreatments and measurements, and (iii) I/I data of the underground fluids in Japan, then gives (iv) some interpretations of the fluid I/I data, along with their problems and uncertainties, and (v) some implications towards evaluating the long-term stability of geological environments.

Identification of hydrogen trapping in aluminum alloys 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

https://doi.org/10.1007/s11661-023-07024-w

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 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 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.

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 C) and stable carbon (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 C (and stable nitrogen isotope, N) and C analyses; and C, N, and C measurements by the use of isotope ratio mass spectrometry and accelerator mass spectrometry (AMS). The guide briefly introduces ways to report 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.

Grain size dependence of meteoric 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

https://doi.org/10.11484/jaea-conf-2018-002

Beryllium-10 (Be) of a cosmogenic nuclide precipitates in forms of BeO and Be(OH) attaching with aerosol on the Earth surface. It is accumulated on the sea- and lake-bottoms. Recently, the meteoric 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 Be exists mostly as hydroxide at pH 5, and is easy to adhere to soil and mineral surface. Therefore, 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 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 Be concentration by JAEA-AMS-TONO.

Growth of single-phase nanostructured ErO 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

https://doi.org/10.1016/j.surfcoat.2015.10.060

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

Boron neutron capture therapy using mixed epithermal and thermal neutron beams in patients with malignant glioma; Correlation between radiation dose and radiation injury and clinical outcome

Kageji, Teruyoshi*; Nagahiro, Shinji*; Matsuzaki, Kazuhito*; Mizobuchi, Yoshifumi*; Toi, Hiroyuki*; Nakagawa, Yoshinobu*; Kumada, Hiroaki

International Journal of Radiation Oncology, Biology, Physics, 65(5), p.1446 - 1455, 2006/08

https://doi.org/10.1016/j.ijrobp.2006.03.016

Clinical trials for boron neutron capture therapy (BNCT) for malignant glioma were performed with thermal-epithermal mixed neutron beam generated by JRR-4. The first protocol (P1998) prescribed a maximal gross tumor volume (GTV) dose of 15 Gy since 1998, and then the protocol was applied to 8 patients. In 2001, a dose-escalated protocol (P2001) was introduced, which prescribed a maximal vascular volume dose of 15 Gy, or alternatively, a clinical target volume (CTV) dose of 18 Gy, the protocol was applied to 11 patients. The GTV and CTV doses in P2001 were 1.1-1.3 times greater than those in P1998. The maximal vascular volume dose of those with acute radiation injury was 15.8 Gy. The mean GTV and CTV dose in long-term survivors with glioblastoma was 26.4 and 16.5 Gy, respectively. A statistically significant correlation between the GTV dose and median survival time was found. In the 11 glioblastoma patients in P2001, the median survival time was 19.5 months and 1- and 2-year survival rate was 60.6 % and 37.9 %, respectively. Dose escalation contributed to the improvement in clinical outcome. To avoid radiation injury, the maximal vascular volume dose should be 12 Gy. For long-term survival in patients with glioblastoma after boron neutron capture therapy, the optimal mean dose of the GTV and CTV was 26 and 16 Gy, respectively. This report introduces principle of BNCT and the activities for the BNCT clinical trials using JRR-4 in JAEA, and the clinical outcomes of the trials under the protocols and radiation injury in the irradiation are described.

Measurement of X-rays from muon to 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

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

Measurement of the K/K ratio of muon to 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

X-ray observation of -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