"Practically all" of Europe's 134 nuclear power reactors need expensive safety upgrades to head off a potential Fukushima-type disaster, upgrades that could cost as much as €25bn.

That's the shocking result of stress tests conducted by the European commission. After the tragedy in Japan in 2011, EU regulators mandated the tests to assess how nuclear reactors in Europe would stand up to earthquakes, floods and airplane crashes. The tests identified "hundreds of technical upgrade measures" that need to be made. They turned up missing seismic equipment, inadequate emergency systems and more, including at least four reactors that would fail within an hour of losing electricity. Still, the report doesn't call for a single plant to be shut down.

Instead, the European commission plans to introduce new laws next year to tighten safety requirements. That might be comforting, except that the stress test report found plants where safety measures mandated decades ago, after the Three Mile Island and Chernobyl meltdowns, had still not been put in place.

Green members of the European parliament, as well as environmental groups such as Greenpeace, say the tests reveal only some of the weaknesses of Europe's nuclear power industry. They're calling for more rigorous tests that include vulnerability to fire, terrorism and human error.

The European commission findings alone are alarming. Is it time for Europe to follow Japan and consider a nuclear phase-out and heavy investment in renewables?

Read more: Greenpeace analyses the inadequacies of the stress tests and reveals even more ways Europe's nukes could go bad in terrifying and massively destructive ways.

Sources: AFP, Avaaz, BBC, EurActive, Greenpeace