nonradioactive

Some elements such as uranium, commonly used as fuel in nuclear power plants, are always radioactive; there is no nonradioactive form of them that naturally occurs in nature.(一些如铀一般的元素，通常在核电厂用作核燃料，都是有放射性的；这些元素由于自身的性质是没有无放射性状态的。)

How it works: A patient inhales haimless nonradioactive Xenon gas, which is tracked by a scanner as it enters the brain.(工作原理病人吸人无害的、无放射性的氙气。氙气进人大脑后由扫描仪进行跟踪。)

Isn't the nonradioactive form of thallium used for rat poison?(铊的非放射性形态不是用于制造老鼠药吗？)