MIT spinout Transatomic Power, a nuclear startup that once claimed to be developing an ultra-efficient reactor that runs on spent nuclear fuel, announced Sept. 25 that it would cease operations.

Transatomic was founded in 2011 by Leslie Dewan and Mark Massie to develop a novel, carbon-free nuclear technology. In March 2014, the company published a white paper claiming its molten-salt reactor design could generate up to 75 times more electricity than a comparable light-water reactor. The same paper asserted that the reactor could run on spent nuclear fuel.

The company’s claims brought it significant mainstream publicity and over $4 million in venture capital.

In early 2016, Transatomic realized there were errors in the original analyses, rendering its design much less efficient and unable to consume nuclear waste. The company has since published additional white papers, the first of which replaced “75 times” with “more than twice” when discussing the molten-salt reactor’s efficiency compared to traditional reactors.

Transatomic continued to work on its reactor design following this setback, citing the design’s reduced waste generation and improved safety. But the extended timeline and reduced performance of the design hampered the funding necessary to build a demonstration reactor, eventually leading to the company’s shutdown.

In the letter announcing Transatomic’s shutdown, cofounder Leslie Dewan said Transatomic will open-source its intellectual property for future developers.

“We’re extremely proud of the great scientific and engineering work we’ve done over the past seven years, and want to make sure that it can continue to further the development of the next generation of nuclear reactors,” Dewan said.

“We will therefore be open-sourcing our intellectual property, making it available for any researchers — private, public, or non-profit — who want to continue the work we’ve started.”