A Dutch nuclear research institute has just fired up the first experiment on next-generation nuclear reactors based on thorium in nearly half a century.
Thorium has long held promise for “safer” nuclear power. A slightly radioactive element, it converts to fissionable U-233 when hit by high-energy neutrons. But after use, U-233 has fewer long-lived waste products than conventional U-235 now used in nuclear power plants. It’s also exceedingly difficult to reprocess thorium into plutonium.
But because nuclear power was traditionally tied up with nuclear weapons research, thorium was abandoned. Except for one test reactor that has been under construction in India since 2004, the last research into thorium reactors took place 45 years ago.
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But now, NRG, a nuclear research facility on the North Sea coast of the Netherlands, has launched the Salt Irradiation Experiment (SALIENT) in collaboration with the EU Commission. The researchers want to use thorium as a fuel for a molten salt reactor, one of the next generation designs for nuclear power.
Molten salt reactors are expected to be very well suited for using thorium as a fuel. The unique fluid fuel can incorporate thorium and U-233 fluorides as part of a salt mixture, to melt at very high temperatures.
The Petten team will melt a sample of thorium salt fuel to see if, over time, the neutron bombardment triggers the nuclear reactions necessary to transmute the thorium into uranium isotopes that can undergo nuclear fission, and sustain the chain reaction needed to generate energy.
If they can produce this cleaner reactor fuel, the next step is to study tough metal alloys and other materials that can survive the bombardment. Later research will examine how to deal with the waste from a molten salt thorium reactor. While safer than the long-lived products from a standard nuke, these will still need special disposal.
If this project bears fruit, there are many interests waiting to join the thorium club. A US startup based in Utah says it’s developing a thorium reactor, the first in the U.S. in half a century, and a consortium of eastern Utah counties is exploring whether to participate in the project. Last month, Utah’s Seven County Infrastructure Coalition issued a request to evaluate “a thorium energy facility for producing electricity”.
So is thorium really back on the table? We’ll know by the end of the year, if the Kalpakkam test reactor in India starts generating energy. We need clean energy sources to stave off climate change, yet fears raised by Fukushima have caused nuclear power to stagnate. Maybe thorium’s time has finally come.