目前情况下值得忧虑的是电离辐射，它由重同位素——如碘131和铯137——自发衰变而生成。

Of concern in the current situation is ionizing radiation, which is produced by spontaneously decaying heavy isotopes, such as iodine 131 and cesium 137.

youdao

这些物质被称作“放射性同位素”—同一种元素的变种，他们具有异常的中子数量，频繁的衰变和放出辐射。

These materials are known as "radioisotopes" -versions of an element that, because they have an abnormal number of neutrons, frequently decay and release radiation.

youdao

原子通过辐射由不稳定状态转变为更加稳定状态的过程称为放射性衰变或放射性。

The process by which an atom changes from an unstable state to a more stable state by emitting radiation is called radioactive decay or radioactivity.

youdao