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Journal Articles

Outlining zircon growth in a granitic pluton using 3D cathodoluminescence patterns, U-Pb age, titanium concentration, and Th/U; Implications for the magma chamber process of Okueyama granite, Kyushu, Japan

Yuguchi, Takashi*; Ito, Daichi*; Yokoyama, Tatsunori; Sakata, Shuhei*; Suzuki, Satoshi*; Ogita, Yasuhiro; Yagi, Koshi*; Imura, Takumi*; Motai, Satoko*; Ono, Takeshi*

Lithos, 440-441, p.107026_1 - 107026_14, 2023/03

https://doi.org/10.1016/j.lithos.2023.107026

Times Cited Count：0 Percentile：0.02(Geochemistry & Geophysics)

We propose a new method for elucidating zircon growth in granitic plutons, based on variations in three-dimensional 3D cathodoluminescence (CL) patterns, U-Pb ages, titanium concentration, and Th/U ratios. We focused on the zircon growth processes in the Okueyama granite (OKG) in central Kyushu, Japan, to obtain interpretations of magma chamber processes that result in the formation of granitic plutons. The OKG consists of three lithofacies: biotite granite (BG), hornblende granite (HG), and hornblende granodiorite (HGD). To determine the 3D internal structure and growth pattern of a zircon crystal, we performed CL observations for multi-sections of the samples. Simultaneously, we also determined the zircon U-Pb age and titanium concentration of the center sections of the samples. The 3D distribution of the oscillatory zoning can be used to determine the crystal nucleus. The simultaneous determination of zircon U-Pb ages and Ti concentrations of the granite samples indicates the time-temperature (t-T) history of granitic magma before its solidification. The t-T histories of the BG, HG, and HGD represented similar cooling behaviors within the magma chamber: rapid cooling from the zircon crystallization temperature to the closure temperature of the biotite K-Ar system between 16 Ma and 10 Ma. The variations in the Th/U ratios against temperature also demonstrate a different trend at the boundary of approximately 670 $^{circ}$ C. Fractional crystallization in the magma chamber progressed significantly at temperatures above 670 $^{circ}$ C; below 670 $^{circ}$ C, crystallization progressed slowly, indicating only minimal changes in the magma composition. The variations in the Th/U ratio against temperature in the BG, HG, and HGD portrayed common tendencies, indicating the same behavior in the progression of fractional crystallization among the three lithofacies, which in turn, represented the same behavior within the entire magma chamber.

Journal Articles

Evaluation of physicochemical properties of radioactive cesium in municipal solid waste incineration fly ash by particle size classification and leaching tests

Fujii, Kengo*; Ochi, Kotaro; Obuchi, Atsushi*; Koike, Yuya*

Journal of Environmental Management, 217, p.157 - 163, 2018/07

https://doi.org/10.1016/j.jenvman.2018.03.028

Times Cited Count：35 Percentile：77.62(Environmental Sciences)

After the Fukushima Daiichi-Nuclear Power Plant accident, environmental recovery was a major issue because a considerable amount of municipal solid waste incineration (MSWI) fly ash was highly contaminated with radioactive cesium. In this study, MSWI fly ash was sampled in Fukushima Prefecture, and the physicochemical properties of radioactive cesium in MSWI fly ash were evaluated by particle size classification and the Japanese leaching test No. 13 (JLT-13). The results obtained from the classification of fly ash indicated that the activity concentration of radioactive cesium and the content of the coexisting matter (i.e., chloride, potassium, and sylvite) temporarily change in response to the particle size of fly ash. X-ray diffraction results indicated that water-soluble radioactive cesium exists as CsCl because of the cooling process and that insoluble cesium is bound to the inner sphere of amorphous matter.

JAEA Reports

Pretreatment works for disposal of radioactive wastes produced by research activities, 1

Ishihara, Keisuke; Yokota, Akira; Kanazawa, Shingo; Iketani, Shotaro; Sudo, Tomoyuki; Myodo, Masato; Irie, Hirobumi; Kato, Mitsugu; Iseda, Hirokatsu; Kishimoto, Katsumi; et al.

JAEA-Technology 2016-024, 108 Pages, 2016/12

JAEA-Technology-2016-024.pdf:29.74MB

Radioactive isotope, nuclear fuel material and radiation generators are utilized in research institutes, universities, hospitals, private enterprises, etc. As a result, various low-level radioactive wastes (hereinafter referred to as non-nuclear radioactive wastes) are produced. Disposal site for non-nuclear radioactive wastes have not been settled yet and those wastes are stored in storage facilities of each operator for a long period. The Advanced Volume Reduction Facilities (AVRF) are built to produce waste packages so that they satisfy requirements for shallow underground disposal. In the AVRF, low-level beta-gamma solid radioactive wastes produced in the Nuclear Science Research Institute are mainly treated. To produce waste packages meeting requirements for disposal safely and efficiently, it is necessary to cut large radioactive wastes into pieces of suitable size and segregate those depending on their types of material. This report summarizes activities of pretreatment to dispose of non-nuclear radioactive wastes in the AVRF.

JAEA Reports

Production and setting of fractional elution facility for recovery of useful rare metals from seawater

Seko, Noriaki; Kasai, Noboru; Tamada, Masao; Hasegawa, Shin; Katakai, Akio; Sugo, Takanobu*

JAERI-Tech 2004-076, 78 Pages, 2005/01

JAERI-Tech-2004-076.pdf:17.11MB

In September 1999, we have soaked 200 kg of fibrous amidoxime adsorbents, synthesized by radiation-induced graft polymerization, into seawater to evaluate their performance. Fractional elution facility was set effectively to elute the rare metals on adsorbents in Mutsu-Establishment. This facility consists of two parts of pre-washing and elution. The present report dealt with planning, manufacture and setting of fractional facility. Marine organism and slime on adsorbent cassette (290290160 mm) were washed out and every 72 cassettes were set in elution unit (12101210H1460 mm) with nonwoven materials as a packing to avoid elution loss. In the elution process alkaline and alkaline earth metals were eluted with low concentration hydrochloric acid (0.01M) and rare metals were eluted with high concentration (0.5M) after the packing of elution unit into fractional elution facility.

JAEA Reports

Study on reducing the generation of general waste

Aoki, Isao; ; Haga, Tetsuya; ; Sudo, Katsuo; Tsunashima, Yasumichi;

JNC TN8420 2000-005, 42 Pages, 2000/04

JNC-TN8420-2000-005.pdf:2.09MB

On August 1999, the Director of Tokai Work proposed an activity regarding recycling and reuse of general waste generated from Tokai Works. The activity was initiated by the Waste Management and Fuel Cycle Research Center, and is now being in progress through out the Tokai Works. In the course of this activity, Plutonium Fuel Center had settled the Working Group and the issues related to the waste reduction have been examined. This report collects the problems that became obvious through the survey of existing segregation method, treatment process, and the amount of the waste generation, and accounts for the concrete methodology for the recycling and reuse of general waste. In order to reduce waste, it is necessary to aware of the facing issues and adopt the countermeasures proposed in this report whenever possible. The activity will then leads us to reduce waste generation, which in turn will enable us to make 100 % waste recycling possible.

Journal Articles