Tests confirm integrity of Deep Isolation disposal canister

Disposal in deep boreholes - narrow, vertical holes drilled deep into the earth's crust - has been considered as an option for the geological isolation of radioactive wastes since the 1950s. Deep borehole concepts have been developed in countries including Denmark, Sweden, Switzerland, and the USA but have not yet been implemented.

Deep Isolation's patented technology leverages standard drilling technology using off-the-shelf tools and equipment that are common in the oil and gas drilling industry. It envisages emplacing nuclear waste in corrosion-resistant canisters - typically 9-13 inches (22-33 centimetres) in diameter and 14 feet long - into drillholes in rock that has been stable for tens to hundreds of millions of years. The drillhole - which is lined with a steel casing - begins with a vertical access section which then gradually curves until it is nearly horizontal, with a slight upward tilt. This horizontal 'disposal section' would be up to two miles (3.2 kilometres) in length and lie anything from a few thousand feet to two miles beneath the surface, depending on geology. Once the waste is in place, the vertical access section of the drillhole and the beginning of its horizontal disposal section would be sealed using rock, bentonite and other materials.

Deep Isolation's Universal Canister System (UCS) - developed in collaboration with NAC International Inc through a three-year project funded by the US Department of Energy (DOE) Advanced Research Projects Agency–Energy (ARPA-E) - is designed to accommodate a range of advanced reactor waste streams, including vitrified waste from reprocessing, TRISO used fuel, and halide salts from molten salt reactors. It is compatible with modern dry storage and transport infrastructure, and meets performance and safety requirements across both borehole and mined repository options, which gives greater flexibility and reduced uncertainty in future waste disposition, the company says.

Project SAVANT (Sequential Advancement of Technology for Deep Borehole Disposal) - a two-year research initiative funded by the DOE's ARPA-E - found that Deep Isolation's UCS and borehole casing materials can sufficiently resist corrosion to safely store radioactive waste material, "further validating the design and advancing the company toward a full-scale deep borehole disposal demonstration".

Building on the project's central objective, the Project SAVANT team evaluated corrosion performance under realistic thermal, chemical, and mechanical stressors expected in a deep borehole environment. These data sets strengthen the scientific basis for Deep Isolation's UCS and reinforce confidence in the system's design life.

"This important study shows that Deep Isolation has achieved another critical milestone in the development of a safe method of disposing of radioactive nuclear waste – something the world critically needs," said Deep Isolation President and CEO Rod Baltzer. "Nuclear energy is facing a growing challenge. Global nuclear power capacity is forecast to increase by more than 300 GW by 2050, yet the world has not permanently disposed of any of the spent fuel it has created over the last 70 years. We believe our deep borehole technology will ultimately be the solution for safely and permanently disposing of nuclear waste deep underground, a solution the world needs."

"The Project SAVANT data significantly strengthens our understanding of how UCS and borehole system materials perform under the conditions expected in a deep geologic environment," said Jesse Sloane, Executive VP of Engineering at Deep Isolation. "These results demonstrate wide margins of safety for the public and reinforce the robustness of our design approach. With these results in hand, we are well positioned to advance into larger scale testing.”
 
Stan Gingrich, Principal Engineer at Amentum and a Project SAVANT collaborator, emphasised the importance of materials research in advancing disposal readiness. "The corrosion testing produced data representative of deep borehole disposal environments," he said. "Our collaboration with Deep Isolation, including our co-authored paper on the results of materials under high temperature and pressure conditions (presented at Waste Management Symposia 2025), underscores how phased testing can bring innovative disposal solutions closer to reality."

The project also incorporated supply chain research and cost estimation developed in partnership with the Electric Power Research Institute (EPRI). These findings highlight opportunities to build domestic manufacturing pathways for canisters, casing materials, and deployment equipment that could accelerate commercial readiness and reduce lifecycle costs for future disposal facilities.
 
Deep Isolation said Project SAVANT supports a broader industry effort to modernise the back end of the nuclear fuel cycle. "As nations expand advanced reactor deployment, durable and predictable disposal pathways are increasingly essential to long-term planning and public confidence. The Project SAVANT findings provide new, data-driven insights that can guide future regulatory, commercial, and technical decision-making for deep borehole disposal."