PARIS, Aug 30 (Reuters) - French state nuclear agency CEA has abandoned research into so-called fourth-generation nuclear reactors, newspaper Le Monde reported on Friday.

The CEA has done years of research and spent hundreds of millions of euros on developing a new sodium-cooled reactor in the ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration) project.

In November last year, the CEA had already said it was considering to reduce ASTRID’s capacity to a 100-200 megawatt (MW) research model from the commercial-sized 600 MW originally planned.

Le Monde quoted a CEA source as saying that the project is dead and that the agency spends no more time or money on it.

Confirming the Le Monde report, a CEA spokeswoman said ASTRID is now “a long-term project, for the second half of this century”. She could not immediately confirm whether the 25-strong team that coordinated the project has been disbanded.

In 2010, the ASTRID project was granted a 652 million euro ($723 million) budget. Media reports have estimated France had budgeted up to 900 million euros through to 2019 for ASTRID.

The sodium-cooled fast-breeder reactor is one of several new designs that could succeed the pressurised water reactors that drive most of the world's nuclear plants. [tinyurl.com/y84d2hvc ]

Instead of water, it uses liquid sodium as a coolant. But sodium burns on contact with air and explodes when plunged into water. An earlier French model was scrapped in the 1980s after having encountering major technical problems.

In theory, breeders could turn nuclear waste into fuel and make France self-sufficient in energy for decades, but uranium prices have been on a downward slope for a decade, which undermines the economic rationale for fast-breeder technology. ($1 = 0.8973 euros) (Reporting by Geert De Clercq; Editing by Leigh Thomas)