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Chicago Pile reactors create enduring research legacy
ARGONNE, Ill. (March 20, 1996) — Next September 21, Argonne NationalLaboratory will open its gates to 20,000-plus visitors to show off itsscientific and educational programs. The center of attention will likely bethe laboratory's new Advanced Photon Source, the nation's most powerful sourceof X-rays for conducting materials research.
But open houses are nothing new at Argonne. The laboratory's first open house,held March 20, 1954, brought some 2,300 people -- mostly employees and theirfamilies -- to the laboratory to tourChicago Pile 5 (CP-5), the nation'snewest nuclear reactor.
ENDURING LEGACY — Chicago Pile 5 was the nation's newest nuclear reactor and the starof Argonne National Laboratory's first open house, March 20, 1954. The reactor was last in thefamous line of Chicago-Pile reactors, whose enduring research legacy continues today.
Like the Advanced Photon Source, CP-5 was a powerful -- for its time --research machine.But instead of X-rays, it used neutrons -- uncharged particles found inthe nuclei ofnearly all atoms. And while it was used for a good deal of materialsresearch starting in the 1970s, its major mission was to study thephysics of atomic nuclei.
During its 25-year career, CP-5 attracted hundreds of scientists from industry,universities and government laboratories all over the world. It opened newhorizons in nuclear physics and materials research. It taught future scientists, trained reactoroperators, and served as a model for many other research reactors in the UnitedStates and abroad.
CP-5 was the fifth and last member of the distinguished family of "ChicagoPile" reactors, whose legacy ranges from the earliest efforts to developnuclear reactors to current environmental research aimed at learning how toretire them safely.
Chicago Pile 1 was the world's first nuclear reactor, built in 1942 by EnricoFermi under the abandoned football stands at the University of Chicago.
Early in 1943, CP-1 was dismantled and moved to a less-populated site in the"Argonne Forest" section of the Cook County Forest Preserve in Palos Park. Thatpart of the forest has since been renamed, but its appellation survives todayin the name of Argonne National Laboratory.
Fermi's reactor was rebuilt in a new configuration and redubbedCP-2. A smalllaboratory atop the 14,000-ton reactor provided space for limited experimentsusing neutrons from the reactor's core. The reactor's face contained portsthrough which materials could be inserted into the core for irradiation.
Chicago Pile 3, a research reactor built in the Argonne Forest in 1944, was theworld's first "heavy-water moderated" reactor . Today, 35 heavy-water reactorsaround the globe generate more than 18 million megawatts of electricity.
The core of a heavy-water moderated reactor is surrounded by water in whichnormal hydrogen atoms have been replaced by deuterium, a heavier form of theelement. Inside the reactor core, uranium atoms split to release neutrons,which strike other uranium atoms, causing them to split in turn and creating achain reaction. If the neutrons move too fast, they are less likely to splituranium. The moderator's job is to slow them down.
There is no "Chicago Pile 4" in the CP lineage. That's because the reactor thatwas called "CP-4" in its early design stages eventually becameExperimentalBreeder Reactor I (EBR-1). Today, EBR-1 is a Registered National HistoricLandmark in recognition of its many historical firsts:
First reactor built at the National Reactor Test Station (known today as theIdaho National Engineering Laboratory).
First reactor to generate usable amounts of electricity, powering a string offour light bulbs on Dec. 20, 1951.
First reactor to demonstrate the "breeder principle," which allows a reactorto create more fuel than it burns.
When Chicago Pile 5 retired from active service as a materials research reactorin 1979, it marked the end of operations for the Chicago Pile reactors.
But today, CP-5 is the site of a new program to develop new technologies tosafely decontaminate and decommission aging facilities. With this program ,the Chicago Pile legacy has come full circle, from pioneering nuclear reactors50 years ago to learning how to retire them safely today.
