US team announces nuclear fuel milestone

Thursday, 13 March 2008

Researchers from the US Department of Energy's lead nuclear research and development laboratory have announced a "major domestic milestone" in the performance of nuclear fuel for use in some of the next generation of advanced nuclear reactors.

INL's Advanced Test Reactor, where the fuel tests were carried out

The team at the Idaho National Laboratory (INL) used reverse engineering methods to "help turn fuel test failures from the 1990s into successes for 2008," according to INL research technical director David Petti. "We wanted to close this loop for the high-temperature gas reactor fuels community," he added.

The fuel in question is coated-particle nuclear fuel for high temperature reactors (HTRs). This fuel, also known as Triso (standing for tri-isotropic), is based on small kernels of uranium oxide or carbide about half a millimetre in diameter. Each of these kernels is coated with several layers of carbon and silicon compounds which form a virtually impermeable barrier against the release of the radioactive products of nuclear fission. Test nuclear fuel elements using Triso technology were tested at INL's Advanced Test Reactor.

 

Development work on HTRs and their fuel began in the 1960s, and in the 1970s and 1980s German companies successfully manufactured fuel and operated two demonstration and experimental reactors. The inherent safety features and small size of the HTR have contributed to bring them once again to the fore in the development of future generations of nuclear power, in programs such as South Africa's Pebble Bed Modular Reactor. A design using Triso fuel is likely to be chosen for the US Department of Energy's Next Generation Nuclear Power Plant (NGNP).

US coated particle fuel programs were unable to match the fuel performance enjoyed by the German project and the research was shelved in the 1990s until its resurrection in 2003. Researchers at INL said that by making the coatings of the US particles more like the German technology of the 1980s they have managed to emulate the German successes.

 

The researchers, a 40-strong team from INL, Babcock & Wilcox, General Atomics and Oak Ridge National Laboratory, say their fuel has now achieved a burnup of 9% without failure and have set their sights on achieving a 12-14% burnup by the end of the year.