and tests from the X-10 Graphite Reactor at Oak Ridge National Laboratory. It was designed to operate at 250 megawatts (thermal).

The purpose of the reactor was to breed plutonium from natural uranium metal. Enriching fissionable ²³⁵U from ²³⁸U, the dominant natural isotope, was extremely complex; plutonium's distinct chemistry made separation trivial by comparison. For example, the