NRG

Thorium has long held promise for “safer” nuclear power. A slightly radioactive element, it transforms into fissionable U-233 when hit by high-energy neutrons. But after use, U-233 creates fewer long-lived radioactive waste products than the conventional U-235 now used in nuclear power plants.

But because nuclear power was traditionally tied up with nuclear weapons research into uranium and plutonium, thorium was mostly abandoned. Except for one test reactor that has been under construction at Kalpakkam since 2004, thorium reactor research has been moribund.

But now, NRG, a nuclear research facility in Petten, 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 in which both the reactor coolant, and the fuel itself, are a mixture of hot, molten salt.


Many believe that molten salt reactors are well suited for using thorium as a fuel. Their unique working fluid can achieve very high temperatures, significantly boosting the efficiency of the power generation process.

The Petten team will use the facility’s reactor to melt a sample of thorium fuel and then bombard it with neutrons to transmute the thorium into U-233, which can sustain the chain reaction needed to generate energy.

A later step is to study tough, temperature-resistant metal alloys and other materials that can survive the high heat and corrosive conditions inside a molten-salt reactor. Eventually, they’ll need to examine how to deal with the waste from a molten salt thorium reactor. While largely considered 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, while a consortium of eastern Utah counties is exploring whether to participate in the project. Last month, Utah’s Seven County Infrastructure Coalition said it is searching for experts qualified to evaluate “a thorium energy facility for producing electricity”.

So is thorium power really back on the table? We’ll know by the end of the year, if the planned Kalpakkam test reactor in India starts generating energy. We will need clean energy sources to stave off climate change, yet fears raised by the Fukushima disaster have caused nuclear power to stagnate. If thorium’s long promise pays off, it’s not a moment too soon.