[M-ZZ45] 地球化学の最前線：その魅力や将来の展望を語り合う

[MZZ45-P11] Challenges of measuring ultra-trace ²³⁷Np in the hydrosphere

榊枝 優真¹、中島 朗久¹、永井 歩夢²、細川 浩由²、横山 明彦²、羽場 宏光³、南部 明弘³、重河 優大³、鄭 建⁴、瀬古 典明⁴、保科 宏行³、Hain Karin⁵、Wiederin Andreas⁵、山﨑 信哉¹、高久 雄一¹、*坂口 綾¹ (1.筑波大学、2.金沢大学、3.理化学研究所、4.量子科学技術研究開発機構、5.ウィーン大学)

キーワード：人工放射性核種、ネプツニウム同位体、スパイク、海水

It is estimated that about 2000 kg of ²³⁷Np, one of the most important nuclides in high-level radioactive waste, has already been released into the surface environment due to human nuclear activities. Since Np is mobile in the environment, it is essential to understand its concentration and distribution in order to understand its behavior and to facilitate its use as a tracer in the water cycle. However, no comprehensive studies have been carried out, especially in aqueous environments, because it is necessary to handle large volume of samples during complicated chemical treatments, and there are no appropriate isotope spikes in mass spectrometry. We have attempted, with the aim of establishing a simpler Np determination method for relatively large volume environmental water samples, to produce ^236gNp as an isotope-spike for ²³⁷Np measurements and to construct a new pretreatment method for large volume environmental water samples.