Schematic of a deep horizontal borehole repository for nuclear waste. (Image: Deep Isolation)
Waste disposal technology company Deep Isolation Nuclear has claimed that results of a study it conducted with reactor developer Oklo demonstrate that deep borehole disposal could be an option for disposing of high-level radioactive waste generated from the recycling of advanced reactor fuel.
Deep Isolation said it completed work under the Department of Energy’s Advanced Research Projects Agency–Energy (ARPA-E) Optimizing Nuclear Waste and Advanced Reactor Disposal Systems (ONWARDS) project titled “Enabling the Near Term Commercialization of an Electrorefining Facility to Close the Metal Fuel Cycle.”
The project: Led by Oklo with partners Argonne and Idaho National Laboratories, the ONWARDS project aimed to enhance technologies for recycling spent fuel in a commercial electrorefining facility. The project was concurrently focused on developing a final waste disposal solution.
Oklo announced in August 2025 plans to design, build, and operate a spent fuel recycling facility in Oak Ridge, Tenn. Earlier, in 2024, the company announced that it had completed the first end-to-end demonstration of its advanced fuel recycling process through the ONWARDS program.
The analysis: Deep Isolation said its analysis confirms that nuclear waste streams partitioned through the Argonne-baseline electrorefining process are compatible with deep borehole disposal.
Modeling showed that HLW, when disposed of in Deep Isolation’s deep borehole system within generic shale and granitic host rocks, achieved long-term safety levels surpassing targets set in developing the model and achieving exposure levels that were several orders of magnitude below a stringent radiological exposure dose standard, the company added.
Should federal law be amended to authorize the disposal of HLW in a borehole repository, Deep Isolation said its technology could offer a viable path for disposing of waste from advanced reactor fuel recycling, highlighting a potential pathway for closing the metal fuel cycle.
He said it: “This collaboration with Oklo represents an important step forward for the advanced reactor ecosystem and our deep borehole disposal solutions for nuclear waste,” said Jesse Sloane, executive vice president of engineering at Deep Isolation. “By pairing innovation in fuel recycling with advanced deep geologic disposal technology, we are helping build the technical foundation for a fully integrated, sustainable nuclear future.”
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