Of concern in the current situation is ionizing radiation, which is produced by spontaneously decaying heavy isotopes, such as iodine 131 and cesium137.
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。
2
The city's challenge, chiefly, is to dispose of cesium-137, a radioactive isotope with a half-life of 30 years.
这座城市面临的最大问题就是处理铯—137，这是一种半衰期为30年的放射性同位素。
3
Once dispersed in the environment, it says, cesium-137 “is impossible to avoid.