衰变链又称放射系(radioactive series)或级联衰变(series decay)。一个连续的核素，其中某一个核素经放射性衰变而转化成下一个核素，直到达于一个稳定核素。
它产生于铀衰变链中的镭，而铀是所有岩石和土壤中都能找到的一种元素，含量各不相同。
It is produced from radium in the decay chain of uranium, an element found in varying amounts in all rocks and soil.
用二进制数对递次衰变链的衰变路径进行编码。
The decay pathways in successive decay chain were coded with binary digits.
氡是天然放射性惰性气体，是铀系衰变链中的一个衰变产物。
As a product from the uranium disintegration, radon is a natural radioactive idle gas.
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