Status of efforts for safeguards challenges by Ningyo-toge Uranium Enrichment Facility

Ishida, Tsuyoshi; Nakashima, Shinichi; Kondo, Shinji; Hayashibara, Kenichi; Yamada, Shigeki*; Okamoto, Ryo*; Nakamura, Hironobu

Dai-44-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2023/11

no abstracts in English

Investigation and consideration on evaluation of radiation doses to residents in the case of a nuclear emergency

Hashimoto, Makoto; Kinase, Sakae; Munakata, Masahiro; Murayama, Takashi; Takahashi, Masa; Takada, Chie; Okamoto, Akiko; Hayakawa, Tsuyoshi; Sukegawa, Masato; Kume, Nobuhide*; et al.

JAEA-Review 2020-071, 53 Pages, 2021/03

JAEA-Review-2020-071.pdf:2.72MB

In the case of a nuclear accident or a radiological emergency, the Japan Atomic Energy Agency (JAEA), as a designated public corporation assigned in the Disaster Countermeasures Basic Act and the Armed Attack Situation Response Law, undertakes technical supports to the national government and local governments. The JAEA is requested to support to evaluate radiation doses to residents in a nuclear emergency, which is specified in the Basic Disaster Management Plan and the Nuclear Emergency Response Manual. For the dose evaluation, however, its strategy, target, method, structure and so on have not been determined either specifically or in detail. This report describes the results of investigation and consideration discussed in the "Working Group for Radiation Dose Evaluation at a Nuclear Emergency" established within the Nuclear Emergency Assistance and Training Center to discuss technical supports for radiation dose evaluation to residents in the case of a nuclear emergency, and aims at contributing to specific and detailed discussion and activities in the future for the national government and local governments, also within the JAEA.

Development of cesium-free mineralization for decontamination and reuse of radioactive contaminated soil in Fukushima

Shimoyama, Iwao; Honda, Mitsunori; Kogure, Toshihiro*; Baba, Yuji; Hirao, Norie*; Okamoto, Yoshihiro; Yaita, Tsuyoshi; Suzuki, Shinichi

Photon Factory News, 35(1), p.17 - 22, 2017/05

http://pfwww.kek.jp/publications/pfnews/35_1/saikin2.pdf

We introduce Cs-free mineralization (CFM) for Cs removal and reuse of radioactive-contaminated soil in Fukushima and report recent work conducted in the BL27A beamline in Photon Factory. In this work, we investigated compositional and structural changes of Cs-sorbed weathered biotite (WB) before and after heating treatment with addition of NaCl-CaCl salts under low-pressure condition, to study Cs desorption mechanism from clay minerals. X-ray fluorescence spectroscopy clarified that almost all Cs and K were removed with the salts at 700 C. On the other hand, Ca increased with heating temperature. X-ray diffraction and transmission electron microscopy analysis clarified that phase transitions from WB to some Ca-rich silicate minerals, e.g., augite, were caused by the heating treatment with the salt. Based on these results, CFM is proposed for Cs removal utilizing the mechanism in which large monovalent cations are discharged with accompanying the phase transition. We also discuss the role of Cl in this reaction showing chemical bonding change of Cl observed using X-ray absorption spectroscopy in the early stage of the chemical reaction.

Desorption behavior of Cs from clay minerals by thermal heating in a vacuum; Analyses by thermal desorption spectroscopy and synchrotron radiation X-ray photoelectron spectroscopy

Hirao, Norie; Shimoyama, Iwao; Baba, Yuji; Izumi, Toshinori; Okamoto, Yoshihiro; Yaita, Tsuyoshi; Suzuki, Shinichi

Bunseki Kagaku, 65(5), p.259 - 266, 2016/05

https://doi.org/10.2116/bunsekikagaku.65.259

After the Fukushima nuclear plant accident, radiocesium was strongly fixed to clay minerals in the soil. Some dry methods with heating are being developed to remove radiocesium from the soil. In this work, we propose a new dry method that combines heat treatment in vacuum and molten salts to reduce the processing temperature in dry methods. Vermiculite saturated with non-radioactive Cs was heated in vacuum, and Cs contents in the vermiculite were compared before and after heating using X-ray photoelectron spectroscopy. Approximately 40% of cesium were removed by heating at 800C for three minutes when only vermiculite was heated. Approximately 70% of cesium were removed by heating at 450C for three minutes when vermiculite was heated with NaCl/CaCl mixed salts. Based on these results, this method is expected to reduce temperature and increase efficiency on dry methods for cesium removal from clay minerals.

Development of fluorescence XAFS system in soft X-ray region toward operando conditions using polycapillary X-ray lens

Honda, Mitsunori; Shimoyama, Iwao; Baba, Yuji; Suzuki, Shinichi; Okamoto, Yoshihiro; Yaita, Tsuyoshi

e-Journal of Surface Science and Nanotechnology (Internet), 14, p.35 - 38, 2016/02

https://doi.org/10.1380/ejssnt.2016.35

A Novel ligand based dual conjugate adsorbent for cobalt(II) and copper(II) ions capturing from water

Awual, M. R.; Yaita, Tsuyoshi; Okamoto, Yoshihiro

Sensors and Actuators B; Chemical, 203, p.71 - 80, 2014/11

https://doi.org/10.1016/j.snb.2014.06.088

Selective cesium removal from radioactive liquid waste by crown ether immobilized new class conjugate adsorbent

Awual, M. R.; Yaita, Tsuyoshi; Taguchi, Tomitsugu; Shiwaku, Hideaki; Suzuki, Shinichi; Okamoto, Yoshihiro

Journal of Hazardous Materials, 278, p.227 - 235, 2014/08

AA2014-0217.pdf:0.96MB

https://doi.org/10.1016/j.jhazmat.2014.06.011

High-energy EXAFS study of molten GdCl systems

Okamoto, Yoshihiro; Shiwaku, Hideaki; Yaita, Tsuyoshi; Suzuki, Shinichi; Gaune-Escard, M.*

Journal of Molecular Liquids, 187, p.94 - 98, 2013/11

https://doi.org/10.1016/j.molliq.2013.05.018

The local structure of molten GdCl and its mixture in LiCl-KCl eutectic was investigated by Gd K-edge extended X-ray absorption fine structure (EXAFS) technique. As the result of curve fitting analysis, the nearest Gd-Cl distance was 2.740.02 with coordination number 6.50.3 in the pure melt. On the other hand, those in the 10%GdCl mixture melt decreased to 2.700.01 and 6.10.3, respectively. These results suggest that octahedral coordination (GdCl) structure is formed and stabilized by mixing with the alkali chlorides. The result was compared with that of YCl and LaCl in LiCl-KCl eutectic melt.

Selective lanthanide sorption and mechanism using novel hybrid Lewis base (N-methyl-N-phenyl-1,10-phenanthroline-2-carboxamide) ligand modified adsorbent

Awual, M. R.; Kobayashi, Toru; Miyazaki, Yuji; Motokawa, Ryuhei; Shiwaku, Hideaki; Suzuki, Shinichi; Okamoto, Yoshihiro; Yaita, Tsuyoshi

Journal of Hazardous Materials, 252-253, p.313 - 320, 2013/05

https://doi.org/10.1016/j.jhazmat.2013.03.020

Trace copper(II) ions detection and removal from water using novel ligand modified composite adsorbent

Awual, M. R.; Ismael, M.*; Yaita, Tsuyoshi; El-Safty, S. A.*; Shiwaku, Hideaki; Okamoto, Yoshihiro; Suzuki, Shinichi

Chemical Engineering Journal, 222, p.67 - 76, 2013/04

https://doi.org/10.1016/j.cej.2013.02.042