A proposed nuclear reactor in Maryland that is close to winning a billion-dollar federal loan guarantee would produce twice the energy of the state's two existing reactors combined.

But the project at Calvert Cliffs faces many hurdles.

Nuclear energy opponents are challenging the reactor's licensing qualifications with charges that the amount of foreign ownership violates the Atomic Energy Act -- which bars nuclear projects with "foreign ownership, control or domination."

The Calvert Cliffs reactor would be built by UniStar Nuclear Energy -- a joint venture between Maryland's Constellation Energy Group and French company Electricite de France. Paris-based Areva would provide the reactor technology.

Electricite de France and Areva are 85 percent owned by the French government.

Foreign ownership and technology risks the safety and quality of nuclear plants, said Michael Mariotte, executive director of the Nuclear Information and Resource Service, a nonprofit that works against nuclear energy.

"We have very strict quality control standards and it is much more difficult to establish that those standards are being met when so many parts are being built 10,000 miles away," he said.

The reactor Areva designed for Calvert Cliffs -- called an evolutionary pressurized reactor -- would be the first of its kind in the United States. Areva is piloting the newly minted technology in Finland -- where the reactor is now delayed three years and the cost has ballooned to 80 percent beyond contracted estimates.

UniStar spokeswoman Kelly Biemer called the Finland reactor a learning experience.

"We will be able to take all those lessons learned and incorporate them into our [Calvert Cliffs] project," she said. "By the time we break ground there will already be four [evolutionary pressurized reactors] under construction."

Critics say taxpayers could be left picking up the tab if the project exceeds its roughly $9 billion cost estimates and has difficulty competing in the power market.

"To build the plant with the loan guarantee in today's power market would be an assurance the taxpayers would get stuck with part of the loan obligation," said former Nuclear Regulatory Commissioner Peter Bradford. "There would be no way out of it."

The loan guarantee program, established in 2005, gives nuclear companies access to low interest rates and promises loan repayment if the company defaults.

Even if the cost of natural gas increases, Mariotte said, the Calvert Cliffs plant will struggle to compete against othergreen energy sources like wind and solar plants.