high-level waste
noun [ U ] uk/ˌhaɪ.lev.əl ˈweɪst/ us/ˌhaɪ.lev.əl ˈweɪst/
高放废物;强放射性废物（诸如用于发电的原子核燃料等产生的废物，放射性强，处理之前需冷藏保存多年，以避免污染破坏环境）
waste, such as nuclear fuel that has been used to produce electricity, that is very radioactive and needs to be kept cool for many years before it can be disposed of without harming the environment