2023 Fiscal Year Final Research Report

Precise life-time measurement of long-lived fission products using precision laser spectroscopy

Research Project

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Project/Area Number	20H00365
Research Category	Grant-in-Aid for Scientific Research (A)
Allocation Type	Single-year Grants
Section	一般
Review Section	Medium-sized Section 31:Nuclear engineering, earth resources engineering, energy engineering, and related fields
Research Institution	Institute of Physical and Chemical Research
Principal Investigator	Takamine Aiko 国立研究開発法人理化学研究所, 開拓研究本部, 研究員 (10462699)
Co-Investigator(Kenkyū-buntansha)	田島美典国立研究開発法人理化学研究所, 仁科加速器科学研究センター, 特別研究員 (20821838) 飯村秀紀国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門原子力科学研究所原子力基礎工学研究センター, 再雇用職員 (10343906)
Project Period (FY)	2020-04-01 – 2024-03-31
Keywords	レーザー分光 / LLFP / 核データ
Outline of Final Research Achievements	Neutron reaction cross sections of long-lived fission products, which are an issue in the eventual disposal of spent nuclear fuel, have been obtained intensively in recent years. On the other hand, there are old and few examples of measurements of the half-life of long-lived fission products, despite the fact that this is extremely important nuclear data. The motivation of this study was to improve the reliability of nuclear data by re-measuring the half-lives of Zr-93 and other long-lived fission products using a new method. Zr-93 was produced in a way that reduced the amount of impurity nuclides in the sample by preparing the sample in a nuclear reaction targeted at the long-lived fission product to be measured. In addition, collinear laser spectroscopy for Zr isotopes was developed to determine the number of atoms that is a parameter necessary for the determination of the half-life.
Free Research Field	不安定核物理
Academic Significance and Societal Importance of the Research Achievements	本研究で対象とする使用済燃料・高レベル放射性廃棄物中の長寿命核分裂生成物は、その分離分析・核変換などにおいて重要な物質であり、その半減期の精査は長期間の核廃棄物リスクの見積もりにとって大きな意味を持つ。また、Zr同位体のレーザー分光はこれまで限られた範囲でのみ遂行されており、本研究で開発した方法により不安定核のオンラインビーム実験による希少Zr同位体の構造研究にアプローチすることで不安定核構造研究への適用も期待できるため、学術的にも意義深いものである。