A paper on the impact of poor borehole sealing on repository performance written by Stefan Finsterle, Cal Cooper, Richard A. Muller, John Grimsich and John Apps, has been published in the peer-reviewed journal Energies. The paper is available online and for download.

A deep horizontal borehole repository offers strong isolation of nuclear waste. The safety afforded by waste isolation at depth relies largely on the natural barrier provided by the horizontal section of the borehole.  A potential for vulnerability may be with the vertical section of borehole that needs to be drilled to build and access the repository. It is important to measure and ensure that the vertical access hole does not provide a direct path through which radionuclides escape from the repository to the land surface. While the borehole will be backfilled and plugged after waste emplacement, it is difficult to assure that the engineered sealing barrier will remain effective over the very long time period for which the waste must be safely isolated.

To investigate the importance of borehole sealing on repository safety, we calculated the radiological exposure dose assuming that the backfill material is of poor quality or has lost its ability to inhibit water flow and radionuclide transport. Our computer simulations indicate that the release of radionuclides through the poorly sealed access hole is small, even if an earthquake destroyed the waste canisters and pushed water along the borehole and into faults. The estimated maximum dose from the release of radionuclides during these adverse events does not increase significantly compared to the nominal scenario and is two to three orders of magnitude lower than a 10 mrem dose standard.

Given that the long-term effectiveness of borehole sealing is difficult to assess or predict, it is reassuring that a deep horizontal borehole repository does not need to rely on the long-term integrity of its seals and backfill material.

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This month marks the two-year anniversary of a Deep Isolation milestone that’s worth pausing to reflect upon as we’re setting our 2021 goals.

As recently as 2018, nuclear industry professionals had dismissed the idea that a newcomer could help solve the nuclear waste problem, a serious environmental challenge that has yet to be addressed globally.  

But on Jan. 16, 2019, we took our first significant leap forward in overcoming such skepticism when we became the first private company to successfully demonstrate publicly to an invited cross-section of government officials, NGOs and investors the emplacement and retrieval of a prototype nuclear waste canister in a test drillhole about half a mile underground. 

The first step of the technology demonstration was the early dawn emplacement of the canister. In this phase, we showed it is possible to successfully lower a narrow long canister deep underground and push it horizontally into place.

 The biggest test was the final stage — retrieval. I still remember the look of pride on the face of our CEO Liz Muller later that night when the mechanical tractor emerged from the drillhole with the canister securely attached — something that at least some in the nuclear industry thought couldn’t be done.

“This proves definitively that canisters deep underground in horizontal drillholes are indeed retrievable,” Muller said as the canister was rose from the ground. “We just did it.” To date, our video of this demonstration has more than 43,000 views. 

Deep boreholes have long been used by oil and gas, and vertical boreholes had been considered for possible nuclear waste disposal, but we demonstrated a concept to use directional drilling to extend the vertical borehole horizontally to safely isolate the radioactive waste under multiple rock barriers far below the earth’s surface.

From Demonstrating Technology to Demonstrating Safety

While we were happy that day in Cameron, Texas, we knew that such a demonstration was only the beginning. We knew that to build a successful nuclear waste disposal company we would have to overcome many hurdles, including regulatory barriers, building community support and studying safety.

The fact that such a demonstration was even able to take place showed we were learning how to build public support networks. We made new friends in this town 75 miles northeast of Austin, and we are using that experience to continue engaging with people from around the world who are concerned about nuclear waste.

Because only a few dozen people could attend in person, we later hosted a webinar to answer questions and share with a wider audience exactly what took place and why.

On the safety front, a little more than a year later we released our first computer-modeled safety analysis: a set of post-closure radiological safety calculations for a generic horizontal drillhole repository sited in shale. 

We continued on a positive 2020 trajectory, winning our first several customer contracts and closing out a $20 million Series A raise that shows there’s a strong appetite among individual cleantech investors for technologies that advance solutions that address nuclear waste.

Looking Ahead to 2021

We plan in 2021 to secure additional contracts with governments and the advanced nuclear industry to study whether our deep borehole disposal solution meets their unique needs. Just last week we blogged about a new in-depth Electric Power Research Institute study of the feasibility of a deep borehole solution, and we expect to soon announce the results of a geology study conducted for an Estonian advanced reactor company.

We also recently published a paper in the independent journal Energies detailing the safety calculations for an unsealed deep horizontal borehole containing nuclear waste. 

To further help governments and advanced reactor organizations worldwide better understand how our solution can work for them, we can now test and demonstrate our solution using the testing facility of our technical advisor, Schlumberger, a world-leading oilfield service provider. 

If you want to know more, just let us know!

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At Deep Isolation we believe that nuclear power is important for achieving a carbon-neutral future and should be deployed in conjunction with a waste disposal program.

There are now about 70 advanced reactor projects being worked on in the U.S., a development that shows promise that this clean technology will be helpful in responding to the pressing need to address climate change. 

Just recently the U.S. Department of Energy announced that five teams will receive $30 million in initial funding for one of its Advanced Reactor Demonstration Programs, with an expectation that the DOE will invest about $600 million over seven years with industry partners matching at least 20 percent.  That’s on top of the $160M awarded through the same program to two teams in October with the expectation that DOE will spend over $3 billion on research for advanced reactors over the next seven years. 

In light of this progress, we are pleased to share the results of a comprehensive report published recently by the Electric Power Research Institute (EPRI) that provides the most detailed analysis to date of how deep horizontal boreholes can offer a safe and secure disposal pathway for waste from advanced nuclear reactors.

The study, a collaboration among EPRI, the Nuclear Energy Institute and other interested organizations, assesses the feasibility of onsite horizontal deep borehole disposal for advanced nuclear energy systems. The 192-page report examines physical site characteristics, disposal operations, safety performance analysis, and regulatory and licensing considerations. The report also outlines an approach to engaging with the public in ways designed to build trust and support for the undertaking. 

At Deep Isolation we believe in solving the nuclear waste problem for future generations. This study provides valuable independent validation of our nuclear waste management solution and maps out a clear path for how we can collaborate with regulators and community members to establish an on-site disposal solution for advanced reactors.

One notable finding is that disposal of advanced reactor waste in deep horizontal boreholes would cost an estimated $478 million compared to $1.56 billion for disposal in a mined repository, representing a 69 percent cost savings. The base case assumed the disposal of 1,000 metric tons of waste from the 20-year operation of an advanced nuclear reactor.

“Innovative technologies, in parallel with the deployment of advanced nuclear reactors, have the potential to broaden our portfolio of used fuel solutions in the United States,” said Rodney McCullum, Senior Director of Fuel and Decommissioning at the Nuclear Energy Institute. “We are always encouraged when government agencies, the private sector or not-for-profit organizations drive new technologies to improve efficiencies, cost, and help secure the future for the next generation of nuclear reactors. NEI is excited about the prospect of deployment of innovative technologies as a complement to any current or future used fuel solutions in the U.S.”

Findings from this study also indicate new opportunities for countries with small nuclear waste inventories or for nations interested in building their first commercial nuclear power plants..  In either case, deep borehole disposal removes a significant cost barrier and provides a solution for a problem that has inhibited nuclear energy for decades. 

To improve customer receptivity and market penetration, we encourage all advanced reactor companies to plan for waste disposal in their product offerings. All too often, customer conversations around advanced reactors fail to consider waste management and we have seen this erode buyer confidence.  On the other hand, kudos to our customer Fermi Energia in Estonia for engaging in an early study of whether local geology is suitable for deep borehole disposal.

Visit EPRI to download the report or to read the executive summary.

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The warmest 10 years on record have all occurred since 1998, with the top eight in the past decade. Climate change is one of society’s most pressing problems as it leads to more extreme weather, rising sea levels, arctic ice melt, and the displacement of coastal communities. 

While the news may seem dire, global warming can be mitigated by drastically decreasing carbon emissions. More people than ever are adopting low-carbon clean energy solutions such as wind and solar, but it’s important to deploy all available technologies, including nuclear energy and especially advanced nuclear reactors.

Current advanced reactor designs showcase more robust safety features, innovative cooling materials and systems, and decreased waste output and cost. For example, Terrapower, an advanced nuclear company founded by Bill Gates, is developing two reactor designs that do not need high-pressure environments to operate, unlike current light water reactors. Its molten chloride fast reactor (MCFR) operates at higher temperatures and therefore higher efficiencies, and makes use of a liquid salt fuel and coolant that allows the reactor to shut down without external power sources, thus preventing accidents. Terrapower’s traveling wave reactor is capable of using depleted uranium as a fuel source, lowering the cost of the overall fuel cycle by using spent fuel from existing reactors. 

Small Modular Reactors Offer More Flexibility

Additionally, there are many small modular reactor designs (SMR) that make nuclear far more scalable and flexible and an attractive choice for baseload energy sources. NuScale is one of the most prominent SMR companies and has recently had its small modular reactor design approved by the Nuclear Regulatory Commission. Its SMR design is only a third of the size of existing pressurized water reactors and will be able to be manufactured off-site, reducing cost. 

SMRs are an option for remote communities that need low-carbon energy that is always available. One good example is Russia’s floating nuclear reactor, Akademik Lomonosov, deployed in 2019 to supply electricity to oil rigs in Russia’s Arctic Ocean. This 80MW mobile power plant generates enough power to provide energy to about 100,000 people.

The chief reasons why nuclear has not been utilized to its potential in the past is the enormous cost of building a light water reactor, and the unresolved issue of nuclear waste.  The SMR and MMR’s make possible the delivery of on-time and on-budget reactors, and now there is a modular disposal option. In addition to the passive safety designs of these innovative reactors, the two chief hurdles to ramped up nuclear power are eliminated. Advanced nuclear energy is low carbon and always on, capable of meeting demands for the smallest of towns to the biggest of cities. Paired with new advancements in renewable energy and energy storage, advanced nuclear technology has the potential to help combat climate change. 

By solving the issue of nuclear waste disposal with innovative and reliable solutions, the nuclear fuel cycle will be complete, and advanced nuclear technology can be more easily deployed and accepted. 

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