Irregularities at nuclear reactors in Germany and Japan in recent weeks have rekindled safety fears and raised tough questions about nuclear energy amid increasing environmental concerns.

The nuclear plant at Brunsbuttel in the northern German state of Schleswig-Holstein is now the world's safest. It's not surprising considering the reactor was shut down following a technical irregularity earlier this month.

Earlier this month, an earthquake caused leaks at a reactor in northwestern Japan and led to low-level radiation, reviving fears about nuclear safety, and the closure of the Brunsbuttel plant in Germany followed a fire at another reactor close to Hamburg.

Around the world, there are 438 nuclear plants currently in operation. The majority are in industrialized nations -- 104 in the US, 59 in France and 31 in Russia.

Despite the recent slew of incidents at nuclear power stations, the International Atomic Energy Agency (IAEA) said the errors in Germany, Sweden and Japan were exceptions and certainly did not pose a danger.