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Some countries may be pushing for further development of nuclear power, but in Germany, many are now debating whether nuclear power is worth the risk. Their fears come at a time of global unease after terror attacks in Belgium. 

In the birthplace of nuclear fission - the anti-nuclear movement is vibrant. Germany has already turned its back on nuclear power. Now pressure groups want a global scaling-back.

"Nuclear technology - in every aspect - is not allowing any mistakes. But human beings do make mistakes all the time, and therefore I'm saying nuclear technology is an inhumane technology and therefore poses a security threat," said Jonathan Lauryn, Int'l physicians for the prevention of nuclear war.

Their fear is not just of mistakes.mThe attacks in Brussels leave no room for doubt about a growing terrorist threat.,And raise questions about how far criminals have the capacity to go - and to what extent authorities can stop them.

Europe has long been alert to the threat of nuclear terrorism. But the arrest of a man allegedly linked to last November's Paris attacks has raised renewed alarm because he was found with surveillance footage of a high-ranking Belgian nuclear official.

In the wake of the latest atrocities, already extremely tight security has been further increased at Belgium's civilian facilities.

Experts say gaining access or stealing from one remains unlikely - and point out the scientific complexity involved remains a factor in governments' favor.

"They know about explosives and about weaponry - and they can organize and plan all that. But that doesn't mean they are also experts on nuclear physics. You might know how to mix up an explosive material - but to distinguish isotopes from each other, and to understand how to use them - is very difficult," said Henning Riecke from German Council on foreign relations.

To proponents, nuclear technology provides untold benefits. But it's the devastating downside that's currently in the spotlight.