Federal regulators have denied the application from Silicon Valley nuclear power start-up Oklo to build and operate its advanced nuclear reactor, dubbed Aurora, in Idaho.

The Nuclear Regulatory Agency filed the decision on Thursday and cited lack of sufficient information about potential accidents and safety measures. Oklo may re-apply.

“Oklo’s application continues to contain significant information gaps in its description of Aurora’s potential accidents as well as its classification of safety systems and components,” said the NRC’s Andrea Veil, in a written statement.

“These gaps prevent further review activities. We are prepared to re-engage with Oklo if they submit a revised application that provides the information we need for a thorough and timely review,” Veil said.

Oklo’s plan is to build miniature nuclear reactors that are much smaller and cheaper than conventional nuclear reactors. Conventional reactors require massive construction projects which are often beleaguered by construction timeline and budget overruns, like the Vogtle plant in Georgia. Oklo’s mini reactors are supposed to be powered by the waste of conventional nuclear reactors and housed in aesthetically pleasing A-frame structures. The company has raised more than $25 million from venture investors to pursue this plan, according to Pitchbook.

The Idaho National Laboratory had announced it would grant Oklo access to used nuclear waste to develop and demonstrate its technology.

The NRC’s decision surprised Oklo, said co-founder and Chief Operating Officer Caroline Cochran.

“It was pretty much as much of a surprise to us as anyone else. We weren’t given any heads up at all before it basically went public yesterday,” Cochran told CNBC. “We really didn’t have any indication that this was coming.”

Cochran launched Oklo in 2013 with her husband Jacob DeWitte, and they began having conversations with the NRC in 2016. In June 2020, Oklo’s application to build an advanced reactor was accepted for review by the commission.

Cochran said in their many meetings with the NRC, they have aimed to provide as much information as they were asked for.

But the NRC pointed CNBC to a letter it wrote to DeWitte stating that the regulators did not get the information they requested.

“Oklo has repeatedly failed to provide substantive information in response to NRC staff requests for additional information (RAIs) on the maximum credible accident (MCA) for the Aurora design, the safety classification of structures, systems, and components (SSCs), and other issues needed for the NRC staff to establish a schedule and complete its technical review,” the letter said.

An MCA is a worse case scenario, explained Scott Burnell, a public affairs officer at the NRC. The agency analyzes an accident “resulting in the greatest radioactive release” possible from a event, hazard or sequence of events.

Cochran said she has been encouraged by some conversations she and the Oklo team have had with members of the NRC since the decision was made public.

“After chatting with some folks with the NRC yesterday after it went public, they made pretty clear that there’s a pathway for us to provide more information again, and just continue the process,” Cochran said.

The NRC did say it has made the decision “without prejudice” and that Oklo “is free to submit a complete application in the future.”

The Oklo decision from regulators was a disappointment to nuclear industry stakeholders. The nuclear industry has been in a pivotal moment of reinvention, working to move past its reputation tarnished by catastrophic accidents, and reinvent itself as a solution to decarbonization efforts which have become a priority in efforts to combat climate change.

“Advanced nuclear technologies, including the Aurora, are being built to help overcome our greatest climate challenges and essential to reaching the nation’s climate goals,” said Doug True, the Chief Nuclear Officer at the industry’s trade group, the Nuclear Energy Institute.

The NRC needs to update its licensing procedures, according to True. “The next generation of nuclear technologies are being designed with inherent safety features and will require the NRC to modernize their approach in licensing the carbon-free nuclear reactors of the future,” he said.

Alex Gilbert, a project manager for nuclear power think tank the Nuclear Innovation Alliance, also told CNBC the decision was a disappointment and a sign of out dated regulatory processes.

“Advanced reactors are expected to be safer than any reactors to date and should be able to meet NRC’s standards,” Gilbert said.

A regulatory overhaul process is in its very early stages, Gilbert said. “This work is ongoing and requires work from industry, NRC, and civil society to ensure efficient licensing,” Gilbert told CNBC.