Chicago Pile-3

Chicago Pile-3. It was the world's first reactor to use heavy water as both a moderator and a coolant, representing a significant evolution in nuclear reactor design following the pioneering Chicago Pile-1. Constructed at the Argonne National Laboratory site, CP-3 was a critical facility for the Manhattan Project and post-war nuclear research, providing essential data for the development of later reactors, including the Materials Testing Reactor and naval propulsion prototypes. Its operation advanced fundamental understanding of neutron physics and isotope production, cementing the laboratory's role as a leader in the nascent field of nuclear engineering.

History and construction

The genesis of Chicago Pile-3 lay in the urgent wartime needs of the Manhattan Project, managed by the United States Army Corps of Engineers. Following the success of Chicago Pile-1 and Chicago Pile-2, scientists at the Metallurgical Laboratory, including Enrico Fermi and Walter Zinn, sought to build a more powerful and versatile research reactor. Construction began in 1943 at the newly established Argonne National Laboratory in present-day DuPage County, Illinois, a site chosen for its relative isolation from Chicago. The project was overseen by the United States Atomic Energy Commission after its creation, with key contributions from physicists like Herbert L. Anderson. The reactor achieved criticality on 15 May 1944, marking a major milestone for the American nuclear program during World War II.

Design and operation

Chicago Pile-3 was a tank-type reactor, a distinct departure from the graphite piles of its predecessors. Its core consisted of natural uranium fuel rods submerged in a cylindrical aluminum tank containing heavy water, supplied by the P-9 Project at facilities like the Trail Smelter in British Columbia. This design made efficient use of neutrons, allowing for a compact core while achieving a significant thermal power output of 300 kilowatts. The heavy water served the dual function of slowing neutrons via moderation (physics) and removing heat as a primary coolant. The reactor was equipped with sophisticated control rods made of cadmium and boron, and its operation provided invaluable experience in handling radioactive materials and managing nuclear fission chain reactions in a liquid-moderated system.

Scientific contributions

The reactor served as a prolific neutron source for a wide array of experiments fundamental to nuclear science. It was instrumental in producing the first substantial American samples of plutonium-239 for study, and it played a key role in early investigations into nuclear cross section data for various elements. Researchers used beams from CP-3 to conduct pioneering work in neutron diffraction and to study the effects of radiation on materials, research that directly informed the design of the Hanford Site production reactors. Furthermore, CP-3 was used to produce important radioisotopes for medical and industrial research, establishing protocols later used at facilities like the Oak Ridge National Laboratory and Brookhaven National Laboratory.

Decommissioning and legacy

After a decade of service, Chicago Pile-3 was permanently shut down in 1954. The decommissioning process involved the removal and disposal of its irradiated uranium fuel and the draining of its heavy water, which was reused in subsequent reactors such as Chicago Pile-5. The reactor vessel itself was eventually buried as low-level waste. The legacy of CP-3 is profound; its successful operation demonstrated the viability of heavy-water reactors, a design pathway pursued by nations including Canada with its CANDU reactor program. The knowledge gained directly contributed to the development of the Experimental Breeder Reactor I and advanced research reactors worldwide, solidifying the foundational engineering principles for both power generation and basic scientific research in the Atomic Age.

Category:Nuclear research reactors Category:Manhattan Project Category:Argonne National Laboratory Category:1944 in science Category:Nuclear history of the United States