A fuel cycle represents the time -- about 25 days -- it takes for the reactor's uranium fuel to become depleted. During operation, HFIR uses the nuclear fission process to produce the world's most intense neutron beams for materials research and isotope production.
"HFIR's unique characteristics are of immense value to both the scientific community, which uses its neutron beams for a wide range of studies on materials, and to industry, which relies on the neutrons for isotope production and advanced materials analysis and development," said ORNL Director Jeff Wadsworth.
HFIR's research community has recently benefited from a series of upgrades supported by DOE's Office of Science. New beam lines, which channel neutrons to experimental instruments, have been installed. A new experiment hall has been constructed, and a "cold source" is in preparation that literally chills the energetic neutrons, slowing them and making them more useful for studying polymers and biological materials.
The reactor also has a new cooling tower and beryllium reflector as part of an ongoing program to upgrade components and infrastructure for another three decades of operation.
Researchers from all over the world come to Oak Ridge to perform experiments at the HFIR. In 2006, the reactor will be joined by the Spallation Neutron Source (SNS) to make ORNL the world's leading center for neutron research.
"SNS and HFIR are complementary. The combination of a world class research reactor with SNS, the world's most powerful pulsed neutron source, is unbeatable," said Jim Roberto, Associate Laboratory Director for Physical Sciences.
While the HFIR produces steady-state beams of neutrons, the SNS will produce neutrons in pulses from an accelerated beam striking a target. HFIR and SNS will be equipped with a suite of state of the art instruments for neutron scattering experiments.
Neutron scattering is a powerful tool for determining the structure and properties of materials at the atomic scale. The technique was developed at ORNL in the 1950s by Cliff Shull and Ernie Wollan. Shull later won the Nobel Prize in Physics for this work.
The reactor also produces radioisotopes used in nuclear medicine. HFIR is the only domestic source of californium-252, an isotope used in industrial analysis. These nuclear materials are processed and refined at the nearby Radiochemical Development and Engineering Center.
"The HFIR team is to be congratulated on this milestone," Roberto said. "HFIR is a unique national facility that owes its success to the long term dedication of hundreds of people."
Oak Ridge National Laboratory is a multiprogram laboratory managed for the Department of Energy by UT-Battelle.