Behind thick glass in a laboratory nestled in French woodland, a silvery molten metal swirls like a liquid mirror. But the material is no mere novelty; as dangerous as it is captivating, it could offer a solution to the nuclear power debate.
For sodium, the sixth-most abundant element on the planet, is being held up as the key to one of several new types of nuclear reactor being developed as governments grapple with the problem of making atomic energy more environmentally friendly, safe and financially viable.
The 2011 Fukushima disaster in Japan effectively brought a global nuclear boom to a halt, but a decade-old research program into new reactors has regained relevance of late.