But they do not stop spontaneous fissions in fuel rods from fuel and fission products .

但他们并没有阻止自然地发生在来自核燃料和裂变产物的燃料棒上的裂变。

Fast reactors , in contrast , do notemploy moderators and use much faster neutrons to produce fissions .

快反应堆，相反，不使用调节器而是使用更快的中子来产生裂变。

The reactor core consisted of pellets ofuranium fuel inside bricks made of graphite , which served as a " moderator " , reducing the speed of the neutrons in order to maximise their ability to causefurther fissions .

反应堆的核心包括：含有球状铀燃料的石墨砖，起到“调节器”的作用，可以减少中子的速度以最大化它们引发进一步裂变的能力。