球床反应堆（英语：Pebble bed reactor，缩写为PBR），亦称卵石床反应堆，是一种先进的核子反应堆设计，1966年于德国首次提出。球床反应堆是高温气冷堆之一，它成为第四代反应堆技术的6个候选堆型之一。这种科技增加了反应堆的安全及效率。反应堆的核燃料密度比一般的反应堆低，就算是失去冷却，亦不会出现核芯熔解。反应堆使用惰性气体或接近惰性气体，如氦、氮、二氧化碳作为冷却剂，在高温下直接驱动涡轮机。由于毋须处理蒸气，系统的热能转换效率可以得到提高。

正在发展这种技术的国家包括有：美国、南非、荷兰等。中国的华能亦与清华大学合作研究；目前已建有10兆瓦的试验反应堆，并计划于五年内兴建第一座商用发电厂。

The pebble-bed reactor (PBR) is a design for a graphite-moderated, gas-cooled nuclear reactor. It is a type of very-high-temperature reactor (VHTR), one of the six classes of nuclear reactors in the Generation IV initiative. The basic design of pebble-bed reactors features spherical fuel elements called pebbles. These tennis ball-sized pebbles are made of pyrolytic graphite (which acts as the moderator), and they contain thousands of micro-fuel particles called TRISO particles. These TRISO fuel particles consist of a fissile material (such as U) surrounded by a coated ceramic layer of silicon carbide for structural integrity and fission product containment. In the PBR, thousands of pebbles are amassed to create a reactor core, and are cooled by a gas, such as helium, nitrogen or carbon dioxide, that does not react chemically with the fuel elements.