UPDATE 2-Finland's TVO wins partial ruling in nuclear reactor dispute with Areva

* Olkiluoto nuclear project almost decade late

* Finnish TVO, French Areva claim billions from each other

* Final decision seen coming in early 2018 (Adds comments, detail)

HELSINKI/PARIS, July 20 (Reuters) - Finnish utility Teollisuuden Voima (TVO) said on Thursday it had received another favourable partial decision from the International Chamber of Commerce (ICC) in its long-running dispute with nuclear reactor supplier Areva.

The companies are claiming billions of euros from each other due to years of delays and cost overruns on the Olkiluoto 3 EPR reactor project in southwest Finland.

The new partial ruling addressed preparation, review, submittal, and approval of design and licensing documents on the project.

“The partial award has finally resolved the great majority of these facts and matters in favour of TVO. Conversely, it has also rejected the great majority of the supplier’s contentions in this regard,” TVO said in a statement.

ICC made a previous partial ruling in November, also in favour of TVO. TVO said there would be at least one further partial ruling before the final one, which Areva said is expected to come early next year.

“We think that this is a significant milestone. This, together with the previous partial decision, further reinforces our view that the balance of the claims is in our favour,” said TVO executive Risto Siilos.

Areva expressed disappointment at the decision.

“We’re talking about a partial decision, not the final decision, which does not deal with some of the key elements put forward by TVO,” said an Areva spokesman.

The project, running almost a decade behind its original schedule, is nearly complete, with power production expected to begin next year.

The cost of Olkiluoto 3 was initially estimated at 3.2 billion euros ($3.7 billion), but Areva in 2012 estimated the overall cost at closer to 8.5 billion euros.

TVO said it was claiming 2.6 billion euros from the supplier consortium Areva-Siemens, while Areva-Siemens has a counter-claim of 3.6 billion euros. Siemens’ role in the project was smaller than Areva’s.

TVO’s owners include Finnish paper companies UPM and Stora Enso as well as utility Fortum.

The EPR reactor is set to become Finland’s fifth and largest, and provide about 10 percent of the country’s power needs. ($1 = 0.8690 euros) (Reporting by Jussi Rosendahl in Helsinki and Benjamin Mallet in Paris, additional reporting by Sudip Kar-Gupta; Editing by Greg Mahlich and David Evans)