Spin excitations of the =1/2 one-dimensional Ising-like antiferromagnet BaCoVO in transverse magnetic fields

Okutani, Akira*; Onishi, Hiroaki; Kimura, Shojiro*; Takeuchi, Tetsuya*; Kida, Takanori*; Mori, Michiyasu; Miyake, Atsushi*; Tokunaga, Masashi*; Kindo, Koichi*; Hagiwara, Masayuki*

Journal of the Physical Society of Japan, 90(4), p.044704_1 - 044704_9, 2021/04

https://doi.org/10.7566/JPSJ.90.044704

Synthesis report on the R&D for the Horonobe Underground Research Laboratory; Project carried out during fiscal years 2015-2019

Nakayama, Masashi; Saiga, Atsushi; Kimura, Shun; Mochizuki, Akihito; Aoyagi, Kazuhei; Ono, Hirokazu; Miyakawa, Kazuya; Takeda, Masaki; Hayano, Akira; Matsuoka, Toshiyuki; et al.

JAEA-Research 2019-013, 276 Pages, 2020/03

JAEA-Research-2019-013.pdf:18.72MB

The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies for geological disposal of High-level Radioactive Waste through investigations of the deep geological environment within the host sedimentary rock at Horonobe Town in Hokkaido, north Japan. The investigations will be conducted in three phases, namely "Phase 1: Surface based investigations", "Phase 2: Construction phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). According to the research plan described in the 3rd Mid- and Long- term Plan of JAEA, "Near-field performance study", "Demonstration of repository design option", and "Verification of crustal-movement buffering capacity of sedimentary rocks" are important issues of the Horonobe URL Project, and schedule of future research and backfill plans of the project will be decided by the end of 2019 Fiscal Year. The present report summarizes the research and development activities of these 3 important issues carried out during 3rd Medium to Long-term Research Phase.

Evolution of the excavation damaged zone around a modelled disposal pit; Case study at the Horonobe Underground Research Laboratory, Japan

Aoyagi, Kazuhei; Miyara, Nobukatsu; Ishii, Eiichi; Nakayama, Masashi; Kimura, Shun

Proceedings of 13th SEGJ International Symposium (USB Flash Drive), 5 Pages, 2018/11

The construction of underground facilities induces fractures in the rock mass around the underground voids due to the resultant stress redistribution. This has particular implications for high-level radioactive waste (HLW) disposal projects, where fracture development creates an excavation damaged zone (EDZ) that increases the hydraulic conductivity of the surrounding rock mass and can provide a pathway for the migration of radionuclides from the storage facilities. It is therefore important to understand the long-term evolution of the EDZ and perform a comprehensive HLW disposal risk assessment. An in situ engineered barrier system experiment was conducted in the 350 m gallery at the Horonobe Underground Research Laboratory, Japan, to observe the near-field coupled thermo-hydro-mechanical-chemical (THMC) process in situ and validate coupled THMC models. Here we investigate the evolution of the EDZ around the gallery and model a test pit that was excavated below the floor of the gallery using a series of seismic tomography surveys. There was a significant decrease in the seismic velocity field around the test pit due to its excavation, which became slightly more pronounced over time after the excavation. These seismic results, coupled with hydraulic tests and pore pressure measurements around the pit, indicate that fracture development and the decrease in saturation around the test pit resulted in a decrease in the seismic velocity field after the excavation of the test pit. Furthermore, the increase in saturation around the test pit is a key reason for the increase in the seismic velocity field after the heater test.

Probabilistic assessment of doses to the public living in areas contaminated by the Fukushima Daiichi Nuclear Power Plant accident

Takahara, Shogo; Iijima, Masashi; Shimada, Kazumasa; Kimura, Masanori; Homma, Toshimitsu

Radiation Monitoring and Dose Estimation of the Fukushima Nuclear Accident, p.197 - 214, 2014/02

AA2013-0338.pdf:0.29MB

https://doi.org/10.1007/978-4-431-54583-5_18

The aim of this study is to provide the scientifically-based quantitative information about a range of received doses to the evacuees from the evacuation areas and the deliberate evacuation areas. To achieve the aim, we adopted a probabilistic approach. The dose assessments were performed based on the measurement data of the surface activity concentrations of Cs and the results of actual survey on behavioral patterns of the population groups living in Fukushima Prefecture. As the result of assessments, the 95th percentile of the annual effective doses received by the inhabitants evacuated from the evacuation areas were mainly in the 1-10 mSv dose band in the first year after the contamination. However, the 95th percentile of the doses received by some outdoor workers, inhabitants evacuated from the deliberate evacuation areas and highly contaminated areas were in the 10-50 mSv dose band.

Assessment of radiation doses to the public in areas contaminated by the Fukushima Daiichi Nuclear Power Station accident

Takahara, Shogo; Iijima, Masashi; Shimada, Kazumasa; Kimura, Masanori; Homma, Toshimitsu

Proceedings of International Symposium on Environmental monitoring and dose estimation of residents after accident of TEPCO's Fukushima Daiichi Nuclear Power Station, p.212 - 220, 2012/12

http://www.rri.kyoto-u.ac.jp/anzen_kiban/outcome/Proceedings_for_Web/Topics_5-06.pdf

In the areas contaminated by radioactive materials due to the Fukushima Daiichi Nuclear Power Station accident, many residents are exposed to radiation through various exposure pathways. To assess the doses realistically and comprehensively, a probabilistic approach was adopted using data that reflected realistic environmental trends and lifestyle habits in Fukushima Prefecture. In the first year after the contamination, the 95th percentile of the annual effective dose received by the inhabitants evacuated from the evacuation areas and the deliberate evacuation areas was mainly in the 1-10 mSv dose band. However, the 95th percentile of the dose received by some outdoor workers and inhabitants evacuated from highly contaminated areas was in the 10-50 mSv dose band. The doses due to external exposure to deposited radionuclides were the dominant exposure pathway, and their contributions were about 90% under prevailing contamination conditions in Fukushima Prefecture. In addition, 20%-30% of the lifetime effective dose was delivered during the first year after the contamination.

Development of new molybdenum adsorbent

Kimura, Akihiro; Tanimoto, Masataka; Ishida, Takuya; Tsuchiya, Kunihiko; Hasegawa, Yoshio*; Hishinuma, Yukio*; Suzuki, Masashi*

JAEA-Technology 2011-012, 17 Pages, 2011/06

JAEA-Technology-2011-012.pdf:1.72MBJP, 2010-263801   Patent publication (In Japanese)

PZC (Poly-Zirconium Compound) was developed as adsorbent of molybdenum for Mo-Tc generator. However, PZC has some faults. So, new adsorbent based on titanium (PTC), was developed for getting rid of faults. This time, Mo adsorption and Tc elution tests with PZC and PTC were carried out. As a result, the Mo adsorption performance of the PTC was lower than PZC, on the other hand, Tc elution performance of the PTC was higher than PZC.

Survey of LEU based Mo production process

Tanimoto, Masataka; Amaya, D.*; Aoyama, Masashi; Kimura, Akihiro; Izumo, Hironobu; Tsuchiya, Kunihiko

JAEA-Review 2011-002, 26 Pages, 2011/03

JAEA-Review-2011-002.pdf:1.46MB

Recently, worldwide demand of Mo became rises. However the availability and supply of Mo for the manufacturing of generators has been a matter of concern. Concern arose from several factors including, amongst others, the shutdown of some nuclear reactors at Canada (NRU, etc.), uncertainty of reliable operating condition for radioisotope production and difficulties in the availability of highly enriched U (HEU) target material used in the majority of the production facilities. As countermeasure for this issue, the HEU is not used but Mo production from low enriched U (LEU) is performed. This production process was developed in Argentina by the Argentine Atomic Energy Commission (CNEA). In the last ten years, INVAP has been working in the supply of Mo production facilities using LEU. This report provides descriptions for the detail technical aspects related to a Mo production system using irradiated LEU targets.

Gradual increase of energetic radiation associated with thunderstorm activity at the top of Mt. Fuji

Torii, Tatsuo; Sugita, Takeshi*; Tanabe, Sachiko*; Kimura, Yoshihisa*; Kamogawa, Masashi*; Yajima, Kazuaki*; Yasuda, Hiroshi*

Geophysical Research Letters, 36(13), p.L13804_1 - L13804_4, 2009/07

https://doi.org/10.1029/2008GL037105

Fluctuations of energetic radiation that seemed to be caused by a summer thunderstorm were observed at the top of Mt. Fuji. The largest of such fluctuations was gradual and lasted for about 20 minutes, and was found to be high-energy rays having a continuous energy spectrum up to 10 MeV or more. As for the feature of these fluctuations, it seems naturally that such fluctuations are caused by the bremsstrahlung photons generated by the energetic electrons produced continuously with an intense electric field in the thundercloud rather than originated in the process of lightning discharge.

Self-regenerating Rh- and Pt-based perovskite catalysts for automotive-emissions control

Tanaka, Hirohisa*; Taniguchi, Masashi*; Uenishi, Mari*; Kajita, Nobuhiko*; Tan, Isao*; Nishihata, Yasuo; Mizuki, Junichiro; Narita, Keiichi*; Kimura, Mareo*; Kaneko, Kimiyoshi*

Angewandte Chemie; International Edition, 45(36), p.5998 - 6002, 2006/09

https://doi.org/10.1002/anie.200503938

no abstracts in English

LaFePdO perovskite automotive catalyst having a self-regenerative function

Tanaka, Hirohisa*; Tan, Isao*; Uenishi, Mari*; Taniguchi, Masashi*; Kimura, Mareo*; Nishihata, Yasuo; Mizuki, Junichiro

Journal of Alloys and Compounds, 408-412, p.1071 - 1077, 2006/02

https://doi.org/10.1016/j.jallcom.2004.12.138

no abstracts in English