Brookhaven Graphite Research Reactor
The Brookhaven Graphite Research Reactor (BGRR) was the Laboratory's first big machine and the first peace-time reactor to be constructed in the United States following World War II. The reactor's primary mission was to produce neutrons for scientific experimentation and refine reactor technology.
In a research reactor like the BGRR, neutrons are captured by uranium nuclei in the fuel elements, causing some of them to undergo fission. Resulting from the fission process are two large nuclear fragments and two to three neutrons. These neutrons are available to initiate new fission events. If, on the average, one of the neutrons from a fission produces another fission, a chain reaction is said to take place. Neutrons which do not cause additional fission reactions and which are not absorbed by the reactor itself are available for experiments. The BGRR was constructed like a cube, with three sides and the top of the cube available for the insertion of experiments which would be irradiated by these neutrons.
Originally, the BGRR was fueled with natural uranium, but, in 1958, a new kind of fuel was introduced that used uranium enriched in the normally rare U-235. The reactor then operated at 20 megawatts with a maximum flux of about 2 x1013 neutrons per square centimeter per second.
At its inception, the BGRR could accommodate more simultaneous experiments than any other existing reactor. Scientists and engineers from every corner of the U.S. came to use the reactor, which was not only a source of neutrons for experiments, but also an excellent training tool.
Researchers used the BGRR's neutrons as tools for studying atomic nuclei and the structure of solids, and to investigate many physical, chemical and biological systems. Scientists also studied the effects of radiation on materials. An estimated 25,000 irradiations were performed over the reactor's lifetime, on specimens ranging from seeds to art treasures. In one such irradiation, engine piston rings were studied in the reactor to determine wear and other characteristics. This work led to the development of multi-grade motor oils, such as 10W-30, now commonly used in automobiles.
Neutrons also served as probes, to study the structure and behavior of other materials. "Loop" experiments were another important area of research, in which measurements were made of the radiation-induced changes in the properties of liquids and gases as they flowed through the reactor. Radioactive isotopes produced at the BGRR were especially useful in medical diagnosis and therapy and in industrial technology. The radioisotope technetium-99m, an important medical diagnostic tool, was developed at the BGRR.
By 1955, however, it was clear that the neutron fluxes available at the BGRR and at research reactors elsewhere were not high enough to support proposed experiments. By 1958, a new reactor concept designed at Brookhaven had been approved by the Atomic Energy Commission for construction. This would become the High Flux Beam Reactor.
The BGRR provided 18 years of service before it was placed on standby in June 1968 and then permanently shutdown. Final decomissioning of the BGRR was begun in the late 1990s. Details on this effort can be found at http://www.bnl.gov/bgrr/ .