崩壊系列

• Reading: ほうかいけいれつ
• Romaji: hokai keiretsu
• Kanji breakdown: 崩 (hou) — collapse, crumble; 壊 (kai) — break, destroy; 系 (kei) — system, lineage; 列 (retsu) — row, series
• Pronunciation: /hoː.kai.keː.ɾe.tsɯ/

Meaning

Decay chain; radioactive series. A sequence of radioactive decays by which an unstable nuclide passes through successive transformations until a stable nuclide is reached.

In nuclear physics and radiochemistry, a 崩壊系列 traces the successive transmutations of a radioactive parent nuclide through intermediate daughter nuclides until a stable end product is formed. The three classical natural series are the uranium, thorium, and actinium series. Understanding decay chains is essential in nuclear waste management, radiometric dating, and radiation safety.

Examples

1. ウランの崩壊系列は最終的に安定した鉛の同位体で終わる。 The uranium decay chain ultimately ends with a stable isotope of lead.
2. 崩壊系列の途中に存在する短半減期の核種は、放射能測定で重要な役割を果たす。 Short-lived nuclides that exist partway through a decay chain play an important role in radioactivity measurements.
3. 放射性廃棄物の管理において、崩壊系列全体の半減期を考慮することが不可欠だ。 In the management of radioactive waste, it is essential to consider the half-lives of the entire decay chain.

Usage Guide

Context: nuclear physics, radiochemistry, geology

Tone: technical

Origin & History

Compound noun: 崩壊 (collapse, decay) + 系列 (series, sequence). The term reflects the sequential nature of radioactive decay — each unstable nucleus collapsing into the next in the chain.

Cultural Context

Era: Showa–Modern

Generation: Adults (specialist)

Social background: Academic/Scientific