Cosmochemical and Geochemical studies on the isotopic variations of elements induced by nuclear reactions in nature

• Hidaka Hiroshi

  Department of Earth and Environmental Sciences Graduate School of Environmental Studies, Nagoya University

Bibliographic Information

Other Title

• 自然界で生じる核反応がもたらす元素同位体変動に基づく宇宙・地球化学的研究
• 2018年度日本地球化学会賞受賞記念論文 自然界で生じる核反応がもたらす元素同位体変動に基づく宇宙・地球化学的研究
• 2018ネンド ニホン チキュウ カガッカイショウ ジュショウ キネン ロンブン シゼンカイ デ ショウジル カクハンノウ ガ モタラス ゲンソ ドウイタイ ヘンドウ ニ モトズク ウチュウ ・ チキュウ カガクテキ ケンキュウ

Abstract

Nuclear reactions are one of major causes of isotopic variations of several elements in natural materials. The Oklo uranium ore in the Francevillian Basin at Republic of Gabon is known as a fossil of natural fission reactor, because large-scaled fission chain reactions spontaneously occurred in the ore two billion years ago. It is of major concern to characterize the properties of the nuclear reactors and to investigate the behavior of fission products in and around the reactors. In this paper, firstly, geological and physicochemical characteristics of the Oklo natural fission reactors and their implications for radioactive waste disposal are shown. In the second, isotopic variations of several elements observed in meteorites and lunar surface materials are reviewed from my previous studies. Spallation reactions and neutron capture reactions induced by the interaction of cosmic rays produce the isotopic variations of some elements in the surficial materials of solar planets without atmospheric layers. Neutron capture-produced isotopic shifts of ¹⁴⁹Sm-¹⁵⁰Sm and ¹⁵⁷Gd-¹⁵⁸Gd have been usefully applied to understand the cosmic-ray exposure histories of meteorites and lunar surface materials. Additionally, several elements of solar primitive materials like carbonaceous chondrites show isotopic variations affected from the input of nucleosynthetic components out of the early solar system. As one of examples, Ba isotopic variations found in chemical separates of the Murchison meteorite are shown.

Journal

• Chikyukagaku

  Chikyukagaku 53 (3), 77-90, 2019-09-25

  The Geochemical Society of Japan

Keywords

• Oklo phenomenon, fission, cosmic rays, meteorites, lunar regolith, neutron capture, isotope

Details

• CRID: 1390564227306838144
• NII Article ID: 130007711844
• NII Book ID: AN00141280
• DOI: 10.14934/chikyukagaku.53.77
• ISSN: 21885923
• ISSN: 03864073
• NDL BIB ID: 030011069
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I030011069
• Text Lang: ja
• Data Source:
  • JaLC
  • NDL
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed