US nuclear waste disposal company Deep Isolation has been awarded a contract to conduct a borehole feasibility study for ARAO, Slovenia's radioactive waste management organisation. The study will examine whether a deep borehole repository could dispose of used fuel from Slovenia's TRIGA II research reactor at the Josef Stefan Institute in Ljubljana.

The 1960s-era reactor - one of 66 of its kind worldwide - produces radioactive isotopes for medical research and for training. It is scheduled to be shut down in 2043.

Under the contract with ARAO, the value of which has not been disclosed, Deep Isolation will evaluate data about the reactor's used fuel; provide cost estimates for a borehole in granite and shale; and provide a timeline.

"We are very interested in the potential for deep boreholes to provide a safe disposal solution for Slovenia's spent nuclear fuel at a lower cost than in a mined repository," said ARAO Head of Planning and Development Leon Kegel. "We are already studying this at the Krško nuclear plant as part of a separate project with Deep Isolation and other ERDO [European Repository Development Organisation Working Group] members. The TRIGA II project gives ARAO the opportunity to evaluate the potential for Slovenia's research reactor fuel."

Deep Isolation noted it has completed other deep borehole disposal (DBD) feasibility studies for advanced nuclear projects, including for the USA's Electric Power Research Institute and Estonia's Fermi Energia.

"Research reactor fuel is an interesting market for Deep Isolation, and waste disposal is still an unsolved problem," said Chris Parker, managing director of Deep Isolation EMEA Ltd. "More countries have research reactors than full-scale power plants. Slovenia is an early adopter in this market, and we expect that the work will show that DBD is a cost-effective solution."

Berkeley, California-based Deep Isolation's solution for the management of used nuclear fuel and high-level radioactive waste involves emplacing it in corrosion-resistant canisters placed in deep horizontal drillholes. The technology uses existing directional drilling technology. The waste can be retrieved during a determined timeframe or permanently secured. In 2019, Deep Isolation publicly demonstrated its concept when it successfully placed and then retrieved a prototype nuclear waste canister hundreds of metres underground via a borehole.