A U.S. regulator has at least temporarily turned down an Idaho company’s pitch to develop a 1.5-megawatt advanced nuclear reactor prototype, citing “significant information gaps” in the initial application.

The Nuclear Regulatory Commission (NRC) said it is “prepared to re-engage” with Oklo Power if it resubmits the plan, and Oklo declared itself “eager to continue moving forward” with the project, Utility Dive reports.

The March, 2020 application “was the first-ever accepted for an advanced plant, so there are many new things for all to learn from and work through to support a successful review, and it provides a foundation from which we can supply additional information and continue work with the NRC,” the company added.

“But the NRC said that, despite several information requests, Oklo’s application continues to contain significant information gaps related to potential accidents and safety systems,” Utility Dive writes.

“These gaps prevent further review activities,” Andrea Veil, director of the NRC’s Office of Nuclear Regulation, said in a statement. “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.”

Oklo claims its design has multiple advantages over present-day nuclear reactors. But Edwin Lyman, director of nuclear power at the Union of Concerned Scientists, pointed to question marks surrounding the application.

“Oklo simply refused to give the NRC the basic information that the agency needs to assess compliance with its regulations and its legal mandate to protect public health, safety, and the environment,” he told Utility Dive in an email.

“The company asserted that its reactor was so small and so safe that it didn’t need to play by the same rules as those used to licence larger reactors,” he added. “But the fact remains that even a very small reactor contains enough highly radioactive material to cause significant radiological contamination in the event of an accident or a terrorist attack.”