Study validates borehole disposal concept for TRISO fuel

Wednesday, 21 May 2025

Project PUCK – for Performance Validation of the Universal Canister System for Kairos Power – has validated the potential use of Deep Isolation’s canister system to safely and cost-effectively manage TRISO spent fuel from Kairos Power’s KP‑FHR fluoride salt-cooled high-temperature reactor.

The Universal Canister System (UCS) is a triple-purpose canister designed to enable the safe storage, transport and permanent disposal of spent nuclear fuel and high-level radioactive waste. Although optimised for deep borehole disposal, the system’s flexible design means it can also be compatible with mined repositories.

The study, which was funded through a US Department of Energy Small Business Innovation Research (SBIR) grant, confirmed that used TRISO fuel is compatible with the UCS and suitable for disposal in both conventional mined repositories and deep boreholes. A detailed economic analysis of the cost benefits of the UCS and borehole disposal approach identified potential process and design enhancements to enable broader commercial adoption across the advanced reactor sector, Deep Isolation said.

The analyses have confirmed that Deep Isolation’s UCS, combined with deep borehole disposal, “offers a viable, cost-competitive, and scalable solution for nuclear waste management” and show that the UCS “is both technically and commercially ready for TRISO fuel”.

“What we’ve accomplished with Kairos Power is more than a technical milestone – it’s a strategic leap toward long-term sustainability in nuclear energy,” said Deep Isolation Executive Vice President Jesse Sloane. “The UCS, paired with deep borehole disposal, offers an adaptable and forward‑thinking end-to-end solution that can serve the advanced reactor industry for the future.”

Earlier this month Kairos began pouring the first nuclear safety-related concrete for its Hermes Low-Power Demonstration Reactor project in Oak Ridge, Tennessee. The TRISO-fuelled reactor – the first non-light-water reactor to be permitted in the USA in more than 50 years – will not produce electricity, but will be followed by a two-unit power generating plant, Hermes 2, as part of Kairos’s iterative approach to deployment of its technology.

“Kairos Power is excited to see the progress made by the Deep Isolation team in advancing the UCS and looks forward to continued collaboration,” Kairos Power Chief Nuclear Officer Per Peterson said. “Together, Deep Isolation and Kairos Power are setting a precedent for innovation, safety, and sustainability in the safe and effective management of spent fuel from high temperature reactors.”