A study conducted by Deep Isolation on behalf of the U.K.’s Nuclear Decommissioning Authority (NDA) concluded that deep borehole disposal cannot replace the U.K.’s need of a geological repository for nuclear waste. However, it may have a useful role to play in the disposal of some of the U.K,’s nuclear waste inventory.
The purpose of the study is to provide the NDA with information that enables it to assess the potential suitability of Deep Isolation’s directional borehole disposal solution for portions of the U.K.’s radioactive waste inventory.
Deep Isolation’s solution for the management of spent nuclear fuel and high-level radioactive waste involves placing it in corrosion-resistant casks which are then inserted into deep horizontal drillholes. This waste storage solution uses existing directional boring technology. The waste can be retrieved within a specific time frame or permanently secured. In 2019, Deep Isolation publicly demonstrated its system when it successfully placed and then retrieved a prototype nuclear waste cask hundreds of feet underground via a borehole.
The study found that sixty three percent by volume of the U.K.’s Inventory for Geological Disposal (IGD) is intrinsically not compatible with borehole disposal. A further twenty six percent can in principle be transferred to Deep Isolation casks for borehole disposal. However, existing plans for nuclear waste disposal in a geological repository will probably be more cost-effective. This leaves about eleven percent of the IGD that is operationally and commercially suitable for disposal in a deep borehole repository. This includes all of the U.K.’s high heat generating waste (HHGW). This accounts for ninety six percent of the NDA’s forecast for radioactivity levels of the IGD in 2200.
In the study, Deep Isolation developed fifteen scenarios which show its estimated, unvalidated cost of disposing of all the U.K.’s HHGW. These describe how costs will vary across geological environments and between single site and multi-site approaches. The scenarios for disposing of one hundred percent show cost estimates between three billion six hundred and forty thousand dollars and five billion four hundred and forty billion dollars. More narrowly focused scenarios show that all of the U.K.’s legacy spent nuclear fuel can be disposed of for one billion seven hundred and twenty thousand dollars. All high-level waste can be disposed of for three billion five hundred thousand dollars.
The study concludes that “Further work is needed to evaluate the impact of such an approach on the overall costs, benefits and risks of the UK's integrated waste management strategy.”
Deep Isolation’s recommendations to the NDA include undertaking more detailed business case work to assess the possible role for the technology as part of the NDA’s integrated waste management strategy and engagement in international collaboration on the demonstrate of deep borehole technology.
Nuclear Waste Services (NWS) is responsible for the delivery of the U.K.’s GDF. It said that it “recognizes the insight afforded by Deep Isolation's study and will continue to engage with such developments, while recognizing that a GDF will still be required for the majority of the UK higher activity waste inventory, even when Deep Isolation's directional borehole technology is developed to sufficient maturity for potential implementation.”
The NWS added “In line with government policy, NDA and NWS continue to review new and emerging technologies which could have the potential to improve the long-term management of some of the UK's higher activity radioactive wastes.”
Elizabeth Muller is the Deep Isolation CEO. She said, “We are excited to have delivered this project for the UK's Nuclear Decommissioning Authority. NDA is a global leader, and I welcome their commitment to exploring the benefit of new and innovative options for nuclear waste disposal.”