RADWASTE MANAGEMENT | FOCUS ON EUROPE


The ARAO study found that... the most cost-effective approach would be to build one deep borehole repository for fuel from both Slovenia’s TRIGA II reactor and the Krško nuclear power plant


There are already examples from two recent Deep Isolation studies, one commissioned by the Norwegian Nuclear Decommissioning Authority (NND) on behalf of a number of countries belonging to the European Repository Development Organisation and another for ARAO, Slovenia’s nuclear decommissioning authority. The NND study, published in December, found that deep


borehole disposal is “a viable and cost-effective option for disposal of ERDO’s high-heat generating waste” – and that it can dispose of 100 per cent of the high-level waste and long-lived intermediate level waste that is being temporarily stored by five European countries: Croatia, Denmark, the Netherlands, Norway, and Slovenia. It estimates that a deep borehole repository would cost one-third to one-half of the cost of a traditional mined repository. The ARAO study found that deep borehole disposal offers


a safe, cost-effective solution for spent fuel from Slovenia’s TRIGA II research reactor and that the most cost-effective approach would be to build one deep borehole repository for fuel from both the TRIGA II reactor and the Krško nuclear power plant. But borehole disposal is not only an option for countries with small spent fuel and radioactive waste inventories. More than half of the respondents believe that it is likely to be suitable, at least to some extent, for managing both small and large inventories.


Challenges of deep boreholes Survey participants were asked to evaluate 26 potential challenges that might need to be overcome. A number of them were identified as being significant, including: demonstrating and documenting in more detail the operational process and safety case; a lack of evidence about societal attitudes regarding boreholes as a disposal design; and the extent to which there is policy or regulatory clarity at an international level about the requirements needed to demonstrate a deep borehole safety case. Eighty per cent of those surveyed agreed or strongly


agreed that the technology needs to be more thoroughly demonstrated end-to-end before it can be implemented as a licensed disposal method; 76 per cent agreed that the operational and post-closure safety case for this method is less well-developed. Almost half of the respondents said they did not know whether deep borehole disposal might bring benefits in terms of increased community acceptance. Some thought boreholes might be seen more favourably, but could not be more definite because societal attitudes to different forms of geological disposal have not yet been well-researched. “The question here is about trust in science, trust in geologists,” said one respondent.


Another said it may be easier for a community member


to understand the simpler structure of a borehole than a complex mining operation that requires workers and equipment underground. One said that the benefit of increased safety at greater depth would be better received, as it would not be so susceptible to tectonic events. Most (80 per cent) stakeholders said they want to see


greater international collaboration on borehole disposal, with the top priority a full-scale (non-radioactive) demonstration.


Demonstrating technical readiness Aspects of the deep borehole technology have still to reach the maturity needed for industrial-scale deployment. Deep Isolation recently completed its first preliminary technology readiness level assessment. Overall, it concludes that spent nuclear fuel handling above ground is the most mature technical industry process and that demonstrating borehole stability and canister emplacement is the highest priority in terms of technology development planning. It is not known whether processes such as pre-closure


monitoring, canister retrieval and borehole sealing will require additional development and demonstration, because that depends on regulatory and risk-informed engineering requirements that are still being developed. Deep Isolation agrees with study participants that an


end-to-end demonstration should be a top priority. In 2019 the company completed a successful retrievability demonstration, where a nuclear waste disposal canister (with no waste inside) was emplaced and retrieved from a pre-existing drillhole in Cameron, Texas. The company is committed to building on this by working with the international community to launch the planning process for a long-term collaborative permanent borehole demonstration. Working with industry partners and government research institutions, it hopes to assemble an independent, science- driven, non-profit task force of experts and citizens to oversee the effort — the first public-private partnership devoted to researching how deep boreholes can be used to dispose of spent nuclear fuel and other types of high-level radioactive waste. The goal of the project is to advance the technical


readiness levels of deep borehole disposal in a progressive, cost-effective and strategic manner, accelerating the preparation for global deployment of this as a licensed disposal technology. The facility, which will not conduct any work with radioactive materials, could serve as a centre of excellence where participants map out, demonstrate and stress-test every step of the end-to-end process for handling spent fuel in Deep Isolation canisters that are transported for disposal into a deep borehole. This project would be guided by four key principles:


1. Transparent and inclusive governance. 2. Community engagement. 3. Scientific excellence. 4. A long-term, phased and prioritised approach.


As one study participant concluded: “The next, very big challenge would be to have a site or to have a test demonstration facility to show that everything that is planned or is expected from the deep hole disposal option is viable, could be implemented, that the safety can be proven also by tests, not only with calculations.” ■


www.neimagazine.com | March 2022 | 29


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45