In the U.S., we would work within the federal framework for geologic disposal. EPA’s 40 CFR Part 191 establishes generally applicable environmental standards for disposal of spent nuclear fuel and high-level radioactive waste, while NRC’s 10 CFR Part 60 contains licensing criteria for geologic repositories.

The current framework was not written specifically for deep borehole disposal, so we would work with the relevant agencies to determine how existing requirements apply and whether additional guidance or rulemaking is needed. A project would also need to address applicable environmental review, drilling and construction requirements, groundwater protection, land use and other federal, state, and local requirements.

There is not one generic one-million-year performance criterion that applies to every U.S. repository. The applicable performance period and regulatory pathway would depend on the waste, site, ownership, and project structure.

10 CFR Part 60 contains a retrievability requirement, generally requiring the repository to preserve the ability to retrieve waste for up to 50 years after emplacement. Our design provides for retrieval during emplacement and the pre-closure operating period. A country’s retrievability requirement for DBD will ultimately dictate how long the borehole remains open (and monitored) before a license for repository closure is granted and acted upon.

Under the current Nuclear Waste Policy Act framework, Yucca Mountain is the designated site for the federal repository program for spent nuclear fuel and high-level radioactive waste, and DOE is restricted from conducting site-specific repository activities at another site without congressional authorization. Deployment of a deep borehole repository for commercial spent nuclear fuel under that federal program would therefore require congressional action, including changes to the NWPA. During Congressional hearings in September 2026, lawmakers and experts reviewed the Administration’s new NLIC framework. The proceedings emphasized a shared recognition between Congress and the Department of Energy that updating the NWPA is a near-term necessity to support these new regional waste management initiatives. Source: U.S. House Committee on Energy and Commerce, “Nuclear Spent Fuel Policy: Examining Nuclear Lifecycle Innovation Campuses,” Sept. 11, 2026, p. 6.

Repository costs vary depending on inventory, geology, regulatory requirements, transportation, project scope and other factors.

The 2024 Amentum paper Cost Comparison for Deep Borehole Disposal as Alternative to Mined Repository compared published cost estimates for mined repositories and deep borehole disposal concepts across multiple countries. Our current cost analysis estimates deep borehole disposal at approximately $424,000 per metric ton of heavy metal for unprocessed spent fuel, compared with approximately $1.2 million per metric ton for mined disposal. Actual costs vary by inventory, geology, repository design and program scope, so these figures should be viewed as indicative rather than direct one-to-one comparisons.

A repository would be sized around the waste inventory, geology and preferred repository architecture, and a program could use one site or multiple sites. Licensing, infrastructure, and other fixed costs therefore need to be evaluated for the specific deployment strategy.

Drilling performance is another important factor in deep borehole economics. Our base economics use single borehole drilling cost estimates as a basis and apply economies of learning as applicable to larger borehole quantity repositories. Though this approach is intended to be conservative, estimates will continue to be refined with time and experience, and contingency budgets based on technology and commercial readiness levels of each applicable WBS item are also calculated in many of our economic studies.

As we collect field data through our full-scale demonstration program, including emplacement, retrieval and planned testing of off-normal conditions, we can use that experience to refine drilling schedules, operating assumptions, contingencies, probabilities, and future project cost estimates.

Interim storage will continue to play a role while permanent disposal facilities are developed. Deep borehole disposal does not eliminate the need for siting, characterization, licensing or community engagement, but its modular design allows construction and disposal to be phased borehole by borehole rather than requiring a large, continuous underground facility to be completed before disposal can begin. That flexibility may be especially relevant for countries or waste streams with smaller inventories.

Ultimately, disposal costs should be viewed in the context of the full lifecycle cost of nuclear energy. Cost is one consideration alongside safety, schedule, siting flexibility, transportation requirements, and implementation risk. Disclosure: Amentum is a licensee of Deep Isolation’s technology.

The approach would depend on the fuel inventory, existing storage system and final disposal package selected. Fuel already stored in existing systems may need to be removed from larger storage canisters and repackaged into disposal canisters suitable for emplacement in a deep borehole.

We evaluated the economics of that additional step in our 2025 paper, Economic Case for Universal Canister System (UCS) in Dry Storage, Transportation, and Disposal. In the reference case, repackaging for disposal was estimated at approximately $290,000 per metric ton of heavy metal. That estimate includes unloading and reloading the fuel, repackaging operations and maintenance, and the capital and decommissioning costs associated with an encapsulation facility. Actual costs would depend on the existing storage system, fuel, and final disposal configuration.

One reason we developed the Universal Canister System is to avoid that additional handling. The UCS is designed as a single canister that can be used across storage, transportation, and disposal, potentially eliminating the need to repackage fuel before disposal. We do, however, recognize that for SNF already packaged in high-capacity dry storage casks, that repackaging is necessary regardless of repository type.

At a deep borehole repository, disposal canisters would be emplaced in the disposal section of the borehole, far below shallow groundwater. Our design provides for retrievability during emplacement and the pre-closure operating period, and emplacement and retrieval are key elements of our full-scale demonstration program. Once disposal operations are complete and a repository is permanently closed, safety is to be maintained by long-term passive isolation.

For context, DOE’s GC-859 survey reports that 314,878 commercial spent-fuel assemblies, representing approximately 90,963 metric tons of initial heavy metal, had accumulated in wet and dry storage through the end of 2022. That does not mean all of those assemblies would need to be repackaged: the amount and type of repackaging required would depend on the storage systems in use and the disposal package ultimately selected.

Community consent is one of the guiding principles in our site-evaluation framework. We would engage early with communities, Tribal governments where applicable, regulators and other stakeholders and would provide access to the safety, environmental and economic information needed to evaluate a project. Independent experts and regulators also have an important role in reviewing the safety case and providing communities with information from sources beyond the project developer.

Community willingness cannot be reduced to a single probability or predetermined outcome; it depends on the project, location, engagement process and community itself. Nor is community acceptance simply a matter of “convincing” people. Our role is to provide clear information, engage transparently, and give communities a meaningful role in evaluating whether a project is right for them.

For a willing host community, potential benefits could include skilled employment, local procurement, infrastructure investment, and other economic benefits while providing a permanent solution for waste that may already be stored in the region. The nature and scale of those benefits would need to be developed transparently with the community and agreed to by them and the government rather than prescribed by the project developer.

Automation and remote handling may change the mix of jobs and reduce worker exposure, but a repository would still require skilled personnel across operations, maintenance, radiation protection, environmental monitoring, and other functions.

Safety begins long before any site is considered. Pre-closure equipment and processes have been designed and developed in a manner consistent with nuclear industry standards (considering mechanical, thermal, shielding, and criticality for normal and off-normal events). The equipment will be fabricated and procedures conducted and refined for our ongoing non-radioactive demonstration program, co-funded by the US Department of Energy.

A few operational-related questions merit discussion here. First, the borehole will be continuously cased and cemented, providing a barrier between the canisters and surrounding rocks. At the beginning of drilling, additional layers of casing and cement are applied at shallower depths to, among other reasons, further isolate the drilling and later emplacement activities from any potential drinking water aquifer. The continuous casing of a set diameter, coupled with the fact that the borehole will be filled with fluid for emplacement operations and the fact that the canister is designed with smooth walls and rounded features, greatly reduces the likelihood of a stuck canister during emplacement operations. This will be tested in the ongoing demonstration program, but it’s also worth noting the canister is designed to withstand a large pulling or pushing force, if needed in a stuck event, and that further contingent procedures will be developed. Post-closure criticality is also often asked about, though it is generally less of a concern than in most other arrangements. The borehole restricts canisters to axial loading only, making critical mass difficult to reach.  Moreover, criticality controls such as fixed neutron poisons, could be inserted into canisters during loading if deemed necessary, similar to how they may be applied in dry storage casks which utilize far tighter radial packing than boreholes. A final common question is what happens if a canister is dropped.  The canister is designed with this in mind, so even though procedures and equipment greatly reduce the likelihood of such an event, the canister is also designed to withstand such hypotheticals.

For post-closure safety, we have developed models and published several reports on DBD in generic, adjustable sedimentary and crystalline geologies.  These reports include sensitivity studies which have in turn informed our site evaluation framework (i.e., what are the key drivers for safety and how can we quantify limits for site screening). Using our framework, we can conduct preliminary regional-level screening to assess technical and economic factors such as seismicity, volcanism, groundwater depth and behavior, proximity to natural resources, and proximity to transport infrastructure. Following an initial screening, a more formal siting process can begin. This would involve discussions with communities and, for willing communities screened earlier as suitable, potential characterization well drilling.  These are small diameter boreholes not to be used for disposal, simply characterizing local geology at different depths.  Post-closure safety models and drilling estimates can be re-run with site-specific data.  Provided technical acceptability in safety and drilling feasibility and community acceptance, sites may be downselected and a selected site may have additional characterization and monitoring conducted depending on the envisioned footprint of a repository.  Explicit borehole designs, inventory assessments, geologic data, and other information will need to be packaged in a license application before any construction can begin.  Even after construction, another round of NRC licensure is required before any operations can begin.  Following operations, another licensure round is needed for closure.  This information is provided to show that repository siting, construction, operation, and closure are phased processes which can take years requiring community and regulator buy in before each step of the process.

Institutional controls, such as records, markers, monitoring, land-use restrictions, or government control, will be part of the process particularly post-closure.  These controls may be active or passive and are intended to reduce the risk of inadvertent human intrusion after closure. Long-term repository safety, however, is intended to rely on geologic barriers with defense in depth afforded by engineered barriers.

Our full-scale demonstration program is testing emplacement and retrieval and is planned to include off-normal conditions and failure response. The goal is to generate field data that can support the operational procedures and site-specific safety case required for future deployment.