Idaho National Laboratory Cultural Resource Management Plan

scarce resource. Only uranium could be used to fuel reactors, and less than 1% of natural uranium is
fissionable uranium-235 (U-235). A breeder reactor could make uranium scarcity a non-issue. In 1947 the
AEC’s General Advisory Committee listed the breeder reactor as one of its high-priority projects.
Zinn and others realized that reactor experiments were too dangerous to expose large population
centers to possible accidents. The AEC Reactor Safeguards Committee recommended in 1949 that reactor
experiments take place at a remote location. After a search for a suitable location, the AEC settled on
Idaho's Navy Proving Ground and set out to transform it as a National Reactor Testing Station. 43
Having settled this matter, the AEC was ready to execute its reactor-research priorities. Argonne
became one of the first clients of the NRTS, responsible for Zinn's breeder reactor experiment, sometimes
referred to by his colleagues as “Zinn’s infernal pile.”
Experimental Breeder Reactor I. EBR-I, the first reactor constructed at the NRTS, was located in the
southwest corner of the site south of U.S. Highway 20/26. Zinn selected the location after a test well
began to produce water. At the time, site engineers did not realize that the Snake River Plain aquifer
underlaid nearly the entire NRTS site and could have supplied water just about anywhere.
Construction of EBR-I began early in 1950, although a local contractor had poured building
foundations in the fall of 1949 to expedite the project. The reactor design, developed at Argonne, already
had been approved by the AEC. The Austin Company of Cleveland, Ohio, was architect/engineer. The
Bechtel Corporation of San Francisco was named construction contractor and took over construction in
the spring of 1950. 44
The multi-level building, completed in April 1951, was made of steel, brick, and concrete. A single
building housed the reactor and control room, as well as utilities and the equipment used for handling,
storing, and cleaning nuclear fuel elements. The building, 122 ft long by 77 ft wide, included a basement,
main floor, and mezzanine level. It was fifty feet high, with subgrade areas thirty feet deep. The project
cost $2,500,000. 45
By January 1951, the building was ready for action. A team of nine scientists arrived at the NRTS
from ANL to assemble the reactor. The reactor was expected to prove the validity of the breeding
principle and demonstrate the use of liquid metal as a coolant. Unmoderated, the reactor was cooled by an
eutectic potassium-sodium alloy (NaK). The reactor was small, with a core the size of a “regulation
football.” The creation of plutonium (breeding) was to occur in two “blankets” of uranium-238 (U-238)
surrounding the core. The reactor was operated with twelve stainless-steel-jacketed U-238 control rods,
eight of which also functioned as safety rods. 46
43. Stacy, Proving the Principle, p. 26-27.
44. Richard G. Hewlett & Francis Duncan, Atomic Shield, 1947-1952: Volume II of a History of the United States Atomic
Energy Commission (University Park, Penn.: Pennsylvania State University Press, 1969) p. 495-496; Holl, Argonne, p. 87;
“Breeder Design Completed, Contractor Selected,” Nucleonics (January 1950), p. 93.
45. “Breeder Design Completed, Contractor Selected,” Nucleonics (January 1950), p. 93.; and E.W. Kendall, D. K. Wang,
Decontamination and Decommissioning of the EBR-I Complex, Final Report (Idaho Falls: Aerojet Nuclear Company Report
ANCR-1242, July 1975), p. 7.
46. W. H. Zinn, “Basic Problems in Central-Station Nuclear Power,” Nucleonics (September, 1952), p. 10-13; Robert L.
Loftness, Nuclear Power Plants: Design, Operating Experience, and Economics (Princeton, New Jersey: D. Van Nostrand
Company, Inc., 1964), p. 335. Hereafter cited as “Loftness, Nuclear Power Plants.”
211