The cold related surge in electricity demand prompted Germany's network operators to call upon nuclear power plants left in reserve as a "preventative measure", a spokeswoman for Tennet, one of the operators, told the newspaper. In the wake of the devastating earthquake and tsunami in Japan last March, which prompted radiation to leak at the Fukushima Daiichi nuclear plant, Germany decided to phase out nuclear power by 2022. Eight of Germany's 17 reactors were immediately taken off line, but five of them are serving as reserve generators in case electricity demand cannot be met from other sources. In December, Germany imported power from neighbouring Austria to stabilise its network.