BORAX Experiments - Evolution of BORAX

Evolution of BORAX

This series of tests began with the BORAX-I nuclear reactor, which proved Samuel Untermyer II's 1952 theory that a reactor using direct boiling of water would be practical, rather than unstable, because of the bubble formation in the core. Subsequently the reactor was used for power excursion tests which showed that rapid conversion of water to steam would safely control the reaction. The final, deliberately destructive test in 1954 produced an unexpectedly large power excursion that "instead of the melting of a few fuel plates, the test melted a major fraction of the entire core." However, this core meltdown and release of nuclear fuel and fission products provided additional useful data to improve mathematical models. The tests proved key safety principles of the design of modern nuclear power reactors. Design power of BORAX-I was 1.4 megawatts thermal. The BORAX-I design was a precursor to the SL-1 plant, which was sited nearby and began operations in 1958. The principles discovered in the BORAX-I experiments helped scientists understand the issues which contributed to the fatal accident at SL-1 in 1961.

Built in 1954, the BORAX-II reactor proved the principles of pressurized water reactors, with a design output of 6 MW(t).

BORAX-II, modified into BORAX-III with the addition of a turbine, proved that turbine contamination would not be a problem. It was linked to the local power grid and for about an hour on July 17, 1955, it provided 2,000 kW to power nearby Arco, Idaho (500 kW), the BORAX test facility (500 kW), and partially powered the National Reactor Testing Station (after 2004, the Idaho National Laboratory) (1,000 kW). Thus Arco became the first city solely powered by nuclear energy. The reactor continued to be used for tests until 1956.

BORAX-IV, built in 1956, explored the thorium fuel cycle and uranium-233 fuel with a power of 20 MW thermal. This experiment utilized fuel plates that were purposely full of defects in order to explore long-term plant operation with damaged fuel plates. Radioactive gasses were released into the atmosphere.

BORAX-V continued the work on boiling water reactor designs, including the use of a superheater. It operated from 1962 to 1964.