原子核反应堆 yuánzǐhéfǎnyìngduī nuclear reactor Origin Definitions Defs Strokes Stroke Words Sentences Sents 原子核 yuánzǐhé atomic nucleus The core of an atom; it is composed of positively charged 质子 zhìzǐ and neutral 中子 zhōngzǐ and contains most of the atom's mass.反应堆 反應堆 fǎnyìngduī reactor A device used to initiate and control a nuclear reaction to produce energy; short for 原子核反应堆 yuánzǐhéfǎnyìngduī.