Argonne National Laboratory’s fast reactors in Idaho

May 23, 2024, 3:01PMNuclear NewsR. N. Blomquist
The Argonne-West laboratory site before it was merged with the Idaho National Engineering and Environmental Laboratory into today’s Idaho National Laboratory. The silver dome in the photo is Experimental Breeder Reactor-II, the silver structure with the flat top and sloping sides is the Zero Power Plutonium Reactor, and the brown boxlike structure behind ZPPR is the Hot Fuel Examination Facility. (Photo: Argonne National Laboratory)

Idaho’s nuclear energy history is deep and rich. The National Reactor Testing Station (NRTS) began its history as an artillery testing range in the 1940s.1 Following World War II, Walter Zinn, Argonne National Laboratory’s founding director and Manhattan Project Chicago Pile-1 project manager, proposed to the Atomic Energy Commission that a remote location be found for building test reactors. In 1949, he and Roger S. Warner, AEC’s director of engineering,2 developed a list of potential sites from which the NRTS was selected. Over the decades, quite a few companies and AEC national laboratories built 52 experimental and test reactors at the NRTS, including 14 by Argonne.3 (For a brief AEC video on the NRTS, see

The legacy of Experimental Breeder Reactor-I

January 31, 2023, 9:30AMNuclear NewsJeremy Hampshire
On December 20, 1951, EBR-I became the first power plant to produce usable electricity through atomic fission. It powered four 200-watt light bulbs and eventually generated enough electricity to light the entire facility. (Photo: DOE)

"At 1:23 p.m. load dissipaters from the generator were connected—electricity flows from atomic energy.” These were the words Walter Zinn wrote in the log after the first four light bulbs were illuminated by nuclear energy. The year was 1951, and the EBR-­I was about to show the world what nuclear energy had to offer.

CP-1 at 80: The events of December 2, 1942

December 1, 2022, 12:01PMNuclear News

On the eve of the 80th anniversary of the first controlled nuclear chain reaction, Nuclear Newswire is back with the second of three prepared #ThrowbackThursday posts of CP-1 coverage from past issues of Nuclear News.

On November 17, we surveyed the events of 1942 leading up to the construction of Chicago Pile-1, an assemblage of graphite bricks and uranium “pseudospheres” used to achieve and control a self-sustaining fission reaction on December 2, 1942, inside a squash court at the University of Chicago’s Stagg Field.

Today we’ll pick up where we left off, as construction of CP-1 began on November 16, 1942.