Idaho National Engineering and Environmental Laboratory

In operation since 1949, the INL is a government reservation located in the southeastern Idaho desert. At 890 square miles (569,135 acres), the INL is roughly 85 percent the size of Rhode Island. It was established in 1949 as the National Reactor Testing Station and for many years was the site of the largest concentration of nuclear reactors in the world. Fifty-two nuclear reactors were built, including the U.S. Navy's first prototype nuclear propulsion plant.

http://www.bwxt.com/operations/ineel.html