So why are things moving faster overseas?

While the U.S. nuclear review process is considered the “gold standard” on safety, some startups and researchers believe it’s not adequately accommodating of advanced technologies. A specific critique is that the commission doesn’t offer the early feedback that would let companies properly assess regulatory risk before investing hundreds of millions of dollars in further design and development.

The Canadian process is better defined and offers a series of earlier official reviews, says Ryan Fitzpatrick, deputy director of the clean-energy program at the think tank Third Way. The commission evaluates designs on the basis of broader safety principles rather than specific technological requirements, which offers greater flexibility for the varied set of emerging technologies, he says.

There have been some efforts to improve the U.S. review process. In March, the Senate’s Environment and Public Works Committee passed the bipartisan Nuclear Energy Innovation and Modernization Act, which would require the NRC to establish a regulatory framework for licensing advanced nuclear reactors. Energy Secretary Rick Perry, in recent public appearances, has also highlighted the importance of pushing forward nuclear technologies, particularly small modular reactors—marking a rare area where the Trump administration is actively promoting a source of carbon-free energy.

Terrestrial’s 190-megawatt integrated molten-salt reactor combines several promising advanced nuclear approaches. Using molten salts rather than water to dissipate heat from the fission process is considered inherently safer, because it allows the reactor to operate at ambient atmospheric pressure. This lowers containment costs and enables cooling even when the system loses power (see “MIT’s Nuclear Lab has an Unusual Plan to Jump-Start Advanced-Reactor Research”).

The IMSR is also a small modular reactor. That means the components can be mass-produced in factories and shipped to their final site, promising to lower construction costs and risks (see “Small Reactors Could Kick-Start the Stalled Nuclear Sector”).

An image of Terrestrial's proposed replaceable reactor core. Terrestrial Energy

Terrestrial is a technology developer and design vendor. It hopes to get its plans preapproved through regulatory agencies and license its technology to other companies that will construct and operate the plants.

CEO Irish says he’s confident the company will be able to address the areas of work highlighted in the review, improving predictions about the behavior of the reactor core and collecting additional data on safety margins and operating performance.

The company’s U.S. affiliate has also begun early regulatory discussions concerning an advanced small modular reactor at Idaho National Laboratory, but it doesn’t plan to submit a licensing application until late 2019.

Many energy experts say the world is going to need far more nuclear power to address the escalating threat of climate change, simply because it’s a carbon-free energy source that doesn’t face the intermittency limitations of renewables like solar and wind.

But the industry has languished amid widespread public safety concerns, massive project costs and risks, high-profile boondoggles, and challenging regulatory requirements (see “Meltdown of Toshiba’s Nuclear Business Dooms New Construction in the U.S.”). Nevertheless, hopes are growing that advanced reactors can overcome some of these issues, helping to restore momentum in the sector.

“Advanced reactors are definitely a big part of getting nuclear to meet its full potential and pull its weight in the climate fight,” Fitzpatrick says.