Learn more here. In 1942, the Manhattan Project needed to create a chain reaction—a crucial step toward proving that it would be possible to make an atomic bomb. The scientists achieved this sustained ...

The U.S. hasn't tested a nuclear weapon in decades, and since the 1990s has used simulations and experiments to verify they're working properly. NPR was granted a rare look at how they do it.

Further investigations 2 demonstrated the existence of at least nine radioactive periods, six of which were assigned to elements beyond uranium, and nuclear ... give rise to a chain of ...