An expected surge in demand for uranium to fuel new reactors may go unfilled if new supply does not soon come on stream, meaning a setback for China, the United States and other countries that are increasingly relying on nuclear energy to power their economies.

While uranium explorers promise to bring projects into production before a major supply crunch develops, most are overestimating their ability to deliver on schedule, industry experts say.

That could leave a vacuum for major uranium producers searching for acquisitions as the most efficient way to ramp up shipments to power utilities that use the radioactive metal to fuel reactors.

"There are juniors out there with projects that are definitely viable," said BMO Capital Markets analyst Edward Sterck. "But I think it'd be fair to say there's an awful lot of juniors who might be challenged to deliver projects on schedule."

At the Prospectors and Developers Conference in Toronto this week, UR-Energy, U308 Corp and Toro Resources were part of a crowd of juniors touting "near production" projects.

Toro is in the permitting stage and will need about A$265 million (US$266 million) to build its Wiluna project in Australia. Managing Director Greg Hall admits the Australian company faces a rough road in getting the mine into production by 2013.

"These things are not fast," said Hall. "Out of those who say they're going to be in production by 2014 - let's say there's 40 - I reckon seven will make it."

That could leave a supply shortage that would have a ripple effect on the global economy should China, India and other Asian powerhouses fail to secure the uranium they need to meet their targets for electricity generation.

China's nuclear generation is set to triple by 2020, while India is looking to double its nuclear output.

In addition, a deal under which the US buys downgraded weapons uranium from Russia is slated to end after 2013. Uranium from the so-called "megatons for megawatts" pact fuels 50 percent of the reactors in the US.

That makes it critical to get new uranium mines online within a couple of years. But permitting problems, financing issues and a lack of management experience are hindering many uranium projects.