UPDATE 1-Areva posts 8.5 percent rise in 9-month sales

* Areva's Olkiluoto 3 reactor in Finland 82 pct complete

* Third quarter sales up 12.4 pct to 2.21 bln euros

* Areva's order backlog rose 10 pct to record 47 bln euros (Updates with details, background)

PARIS, Oct 25 (Reuters) - Areva, the world's biggest maker of nuclear plants, posted an 8.5 percent rise in nine-month like-for-like sales on Thursday, supported by growth in its nuclear energy businesses and the effects of a restructuring.

Areva embarked on an overhaul of its business in December 2011 in response to the effects of Japan's Fukushima disaster on the nuclear industry, which has prompted some countries such as Germany and Belgium to decide to quit nuclear energy.

Nine-month revenues reached 6.54 billion euros ($8.48 billion) and for the third quarter alone revenues rose 12.4 percent to 2.21 billion euros on a like-for-like basis, Areva said.

Areva's order backlog rose 10 percent to a record 47 billion euros at the end of September from three months earlier. Orders over the first nine months of the year were up 87 percent compared with the same period in 2011.

But order cancellations attributable to the Fukushima nuclear disaster rose by 95 million euros in the third quarter, and totalled 742 million euros by the end of the third quarter.

Areva had said in December it would cut investments and sell assets to shore up its balance sheet as a result of a plunge in demand following the Fukushima nuclear disaster in Japan.

Areva gave itself a target of selling 1.2 billion euros of non-strategic assets over two years, but the state-owned group said in July it would already hit that goal this year.

Areva's Olkiluoto 3 nuclear reactor in Finland is now 82 percent complete, the French state-owned group said, adding the testing and fine-tuning phase had started.

($1 = 0.7716 euros) (Reporting By Muriel Boselli and James Regan; Editing by Gus Trompiz and Jane Merriman)