Located within the Palos Forest Preserve, approximately 20 miles southwest of downtown Chicago, in an area named the Red Gate Woods, are two spots designated Site A and Plot M. Site A is 19 acre in size and contains the buried remains of the world’s first nuclear reactor, while the 150 feet by 140 feet area known as Plot M is a radioactive waste dump.
The world's first nuclear reactor designated Chicago Pile-1 (CP-1) was built at the University of Chicago, under extreme secrecy as part of the Allied effort to build the atomic bomb during the Second World War. The reactor was assembled in November 1942, under the watchful eyes of such prominent physicists such as Enrico Fermi and Leo Szilard, the discoverer of the chain reaction. On a cold December morning in 1942, less than a month later, the first man-made self-sustaining nuclear chain reaction was initiated. There was no big bang, but this humble beginning was the true dawn of the nuclear age.
Marker at Plot M. Photo credit: Federal Government of the United States
The reactor in Chicago, described by Fermi as "a crude pile of black bricks and wooden timbers", consisted of 360 metric tons of graphite, used as a neutron moderator to slow down neutrons, and was fueled by 5.4 tons of uranium metal and 45 tons of uranium oxide. Because the reactor was designed to operate at very low power, it had no radiation shield nor any cooling system. Nevertheless, it was a radiation hazard to everyone in the vicinity. So shortly afterwards, the reactor was dismantled and moved to a forest outside Chicago and rebuilt at an area now called Red Gate Woods. The reactor was renamed Chicago Pile-2.
Chicago Pile-2 (CP-2) was bigger and more powerful, running at a few kilowatts, and it had a radiation shield. CP-2 was joined by another reactor Chicago Pile-3. Both reactors operated for ten years before they outlived their usefulness, and was shutdown in 1954.
A gigantic hole was dug in the forest, and both reactors pushed into the hole by detonating strategically placed explosives. All buildings on Site A were torn down and were also buried. The excavation was then backfilled, leveled, and landscaped. The top of the CP-3 reactor shield is approximately 23 feet below ground surface. Rubble and building debris fill the excavation both laterally and vertically to within a few feet of the surface.
Two granite blocks now mark Site A and Plot M.
The Site A marker reads:
THE WORLD'S FIRST NUCLEAR REACTOR WAS REBUILT AT THIS SITE IN 1943 AFTER INITIAL OPERATION AT THE UNIVERSITY OF CHICAGO THIS REACTOR (CP-2) AND THE FIRST HEAVY WATER MODERATED REACTOR (CP-3) WERE MAJOR FACILITIES AROUND WHICH DEVELOPED THE ARGONNE NATIONAL LABORATORY THIS SITE WAS RELEASED BY THE LABORATORY IN 1956 AND THE U.S. ATOMIC ENERGY COMMISSION THEN BURIED THE REACTORS HERE.
The Plot M marker reads:
CAUTION—DO NOT DIG Buried in this area is radioactive material from nuclear research conducted here 1945–1949. Burial area is marked by six corner markers 100ft from this center point. There is no danger to visitors. U.S. Department of Energy 1978.
A sketch of Chicago Pile-1. Photo credit: Melvin A. Miller of the Argonne National Laboratory
After removing any remaining radioactive fuel and heavy water coolant, CP-2 and CP-3 were buried. Other contaminated materials were disposed of at nearby Plot M. Photo credit: fpdcc.com
Scientists at Site A Commemorative Boulder. Photo credit: fpdcc.com
A mountain biker rides past the stone marking at Site A. Photo credit: Philip Scott Andrews/The Wall Street Journal
Marker at Site A. Photo credit: Federal Government of the United States
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