Thorium fuel assemblies have completed thermal-hydraulic tests at Russia's Kurchatov Institute.
The experimental nuclear fuel rods, based on thorium instead of uranium, were subjected to pressure and temperature conditions that could be found in commercial light-water reactors during an emergency. One test was conducted on a 1 m long fuel assembly akin to those used in Russian-designed VVER pressurised water reactors. The other on a partial assembly similar to those used in Western equivalent designs.
The experiments were carried out over three years at the Kurchatov Institute for US-based Thorium Power, a technology company developing thorium fuel designs. Russia's OKBM design bureau also participated.
Eric Holstrom of Thorium Power told World Nuclear News that the company is moving from a scientific development phase to an 'engineering executional' phase. With the results of the recent tests, which indicate Thorium Power's design could be scaled up further to full size.
In about three years, Thorium Power hope to begin full-size tests which will take another three years. After that the company hopes to gain regulatory approval for the fuel to be used in commercial reactors, at which point it would licence or sell the technology to established nuclear fuel manufacturers.
This program to qualify the fuel for widespread use - first in VVERs, then in other light water reactors - is Thorium Power's main priority. The other is to develop a market for the fuel. Dennis Hayes, vice president of the company, told WNN that it has been approached by various "players in the nuclear industry" including governments and companies interested in building new nuclear power plants. Hayes said that as the work program has progressed he had seen the companies make "increasingly firm commitments."
Thorium presents interesting possibilities for the nuclear industry. It is more abundant that uranium and its use leads to the production of only very small amounts of plutonium. Furthermore, Thorium Power say the radiotoxic profile of used thorium fuel is dramatically different to that of uranium fuel. Because the fuel could stay in a reactor longer (parts of fuel assemblies could remain in a reactor for three or even nine years) more of the highly-radioactive actinides produced by fission are 'burnt'. This means used thorium fuel will decay to background levels of radioactivity in around 100 years.
WNA's Thorium information paper