By Andrea Shalal

WASHINGTON (Reuters) - Lockheed Martin Corp said on Wednesday it had made a technological breakthrough in developing a power source based on nuclear fusion, and the first reactors, small enough to fit on the back of a truck, could be ready in a decade.

Tom McGuire, who heads the project, said he and a small team had been working on fusion energy at Lockheed's secretive Skunk Works for about four years, but were now going public to find potential partners in industry and government for their work.

Initial work demonstrated the feasibility of building a 100-megawatt reactor measuring seven feet by 10 feet, which could fit on the back of a large truck, and is about 10 times smaller than current reactors, McGuire said.

In recent years, Lockheed, the Pentagon's top supplier, has been increasingly involved in a variety of alternate energy projects, including several ocean energy projects, as it looks to offset a decline in U.S. and European military spending.

Lockheed's fusion energy project could help in developing new power sources amid increasing global conflicts over energy, and as projections show there will be a 40 percent to 50 percent increase in energy use over the next generation, McGuire told reporters.

If it proves feasible, Lockheed's work would mark a key breakthrough in a field that scientists have long eyed as promising, but which has not yet yielded viable power systems. The effort seeks to harness the energy released during nuclear fusion, when atoms combine into more stable forms.

"We can make a big difference on the energy front," McGuire said, noting Lockheed's 60 years of research on nuclear fusion as a potential energy source that is safer and more efficient than current reactors based on nuclear fission.

Lockheed sees the project as part of a comprehensive approach to solving global energy and climate change problems. Compact nuclear fusion would also produce far less waste than coal-powered plants, and future reactors could eliminate radioactive waste completely, the company said.

McGuire said the company had several patents pending for the work and was looking for partners in academia, industry and among government laboratories to advance the work.

Lockheed said it had shown it could complete a design, build and test it in as little as a year, which should produce an operational reactor in 10 years, McGuire said. A small reactor could power a U.S. Navy warship, and eliminate the need for other fuel sources that pose logistical challenges.

U.S. submarines and aircraft carriers run on nuclear power, but they have large fusion reactors on board that have to be replaced on a regular cycle.

"What makes our project really interesting and feasible is that timeline as a potential solution," McGuire said.

(Editing by Jeffrey Benkoe)