In 1942, he became head of the Metallurgical Laboratory, with responsibility for producing nuclear reactors to convert uranium into plutonium, finding ways to separate the plutonium from the uranium and to design an atomic bomb.
1942年，他成为冶金实验室的领导人，负责建造将铀转化为钚的核反应堆、寻找将钚从铀中分离出来的方法以及设计原子弹等工作。