Deep Isolation Nuclear has announced the results of a three-year project funded by the U.S. Department of Energy, demonstrating that deep borehole disposal can provide a safe and economically viable pathway for high-level waste generated by the recycling of spent nuclear fuel. All scenarios analyzed met the program’s safety criteria, with projected public radiation doses — in most cases — several orders of magnitude below the regulatory benchmark of 10 millirem per year.
The project is part of the Department of Energy’s ARPA-E CURIE program and was carried out in collaboration with Argonne National Laboratory, advanced reactor company Oklo Inc., and Case Western Reserve University. Deep Isolation led the disposal component, assessing how waste streams from fuel recycling could be packaged and permanently isolated underground. The analysis examined the company’s proprietary Universal Canister System, tested in both horizontal and vertical configurations within deep boreholes.
On the economic side, all scenarios studied came in below the program’s target of less than 0.1 cents per kilowatt-hour of electricity generated. This result directly challenges one of the most frequently cited arguments against nuclear power — that waste management makes the entire fuel cycle economically unworkable. While fuel recycling recovers usable fissile materials, it still leaves behind a fraction of high-level waste requiring a permanent solution. The research demonstrates that deep boreholes can be that solution, without meaningfully adding to the overall cost of power generation.
Project partner Oklo aims to close the fuel cycle through pyroprocessing: recovering usable materials from spent fuel, converting them into new fuel, and feeding them back into its advanced fast reactors. The residual waste — far smaller in volume than intact spent fuel — then becomes the target for deep borehole disposal. Physical analyses showed that high-level waste isolated within Deep Isolation’s system inside shale and granite rock formations achieves long-term safety performance well above the model’s targets.
Deep Isolation is the first company to have developed technologies specifically designed for the disposal of nuclear waste in deep boreholes. The underlying logic is straightforward: place waste at depths where geological stability is guaranteed for millennia, leveraging the natural properties of the host rock as an additional barrier. The findings of this study reinforce the case that co-designing recycling and disposal systems — rather than treating waste management as an afterthought — yields more robust, verifiable solutions from the outset.
The next steps will also depend on how U.S. regulations evolve: federal law will need to be updated to explicitly authorize the disposal of high-level waste in deep boreholes. Should that regulatory framework materialize, Deep Isolation‘s technology will be ready to support Nuclear Lifecycle Innovation Campus facilities — the integrated recycling and disposal hubs that the industry is beginning to plan — providing a concrete answer to the question of what to do with waste from next-generation reactors.
