“We have to understand the ubiquity of energy in everything we do. Energy is core to our economy and it brings with it environmental challenges, and it’s core to our security challenges.” -Ernest Moniz
In 1953, then-President Eisenhower, in the aftermath of World War II and with rising tensions between the USA and the Soviet Union resulting in a nuclear arms race, began the “Atoms For Peace” plan. The idea was that all nations should be able to reap the benefits of nuclear power, while simultaneously keeping the world safe from nuclear war. While the same ingredients can be used for both reactors and weapons, uranium and plutonium, there’s are big differences reactor-grade and weapons-grade materials.
The largest difference is the concentration of fissile material. When the United States helped broker a deal with Iran to give them nuclear power capabilities while keeping their possibility of creating nuclear weapons at a minimum, it was nuclear physics that sealed the deal. In particular, it was likely unprecedented negotiation on two issues that made it possible: the U-235 and Pu-239 concentrations that would arise from Iran’s nuclear program.