DUESSELDORF/FRANKFURT (Reuters) - Germany's No.2 utility RWE is preparing to sue for millions of euros of damages after a federal court confirmed that a state's decision to shut down the company's Biblis nuclear plant for three months in 2011 was illegal.
A spokeswoman for RWE said it planned the lawsuit over Biblis, Germany's oldest nuclear plant, which the state of Hesse had ordered closed as a precaution following the disaster at Japan's Fukushima plant.
The spokeswoman declined to comment on the potential size of the claims but industry analysts have estimated that RWE suffered about 187 million euros ($255 million) in damages as a consequence of the forced shut-down.
Shares in RWE, Germany's second largest utility by market value after E.ON, rose after the news and were up 4.7 percent, topping the German benchmark DAX index.
RWE had filed a complaint in April 2011 against the state of Hesse. Last February, the Hesse Administrative Court said the order had been illegal, a decision that was backed by Germany's Leipzig-based Federal Administrative Court on Tuesday.
The Fukushima disaster later also triggered Germany's decision to exit nuclear power by 2022, forcing Germany's top utilities - E.ON, RWE, EnBW and Vattenfall - to book billions of euros of writedowns and cut thousands of jobs.
Biblis has remained idled since 2011.
RWE estimates that dismantling its two reactors at Biblis will cost 1.5 billion euros, excluding storage costs for the nuclear waste. ($1 = 0.7324 euros)
(Reporting by Tom Kaeckenhoff and Christoph Steitz; Editing by Anthony Barker)