US-based start-up NANO Nuclear Energy has assembled the first reactor core hardware of its ZEUS microreactor for initial non-nuclear testing. The assembled hardware consists of a 1:2 scale block, precisely engineered to be representative of a fuel element of the ZEUS microreactor core.
The ZEUS solid core battery reactor design has a sealed solid core that relies on a highly conductive moderator matrix to dissipate the fission energy with no in-core fluid system. The reactor core and power conversion system fit within a single standard shipping container, facilitating transportation to remote sites, providing on-demand capable, clean, scalable power for data centres, remote locations, industrial sites, military operations and disaster relief scenarios, the company says.
“Achieving this hardware milestone represents a major step forward in our ZEUS microreactor program,” said James Walker, Chief Executive Officer of NANO Nuclear. “This testing will provide our team with the key thermal and mechanical insights needed to fine-tune the core design before full-scale fabrication and regulatory engagement.”
NANO says the validation of the reactor core through scaled testing will position it to advance toward full prototype construction and licensing efforts in the coming years. The initial testing phase will focus on the assessment of the thermo-mechanical performance of the block under anticipated prototypical conditions for ZEUS. The results will inform the next stages of reactor development. The results will be crucial for verifying engineering plans, refining physics models, and optimising ZEUS core and heat management systems.
“We are very excited to have completed the first ZEUS reactor core block for non-nuclear testing,” said Professor Peter Hosemann, Head of Nuclear Reactor Design & Materials at NANO Nuclear. “This very precise component will be heated conventionally using linear heaters as fuel rod surrogates. The test will be used to verify temperature distribution, to investigate fit tolerances, and to confirm and benchmark our models, paving the way for a larger sub-core assembly.”
Professor Massimiliano Fratoni, NANO Nuclear Senior Director and Head of Reactor Design said he was thrilled about the transition from design to hardware assembling and testing for a key component of our ZEUS reactor. “The lack of an in-core fluid in our ZEUS design not only simplifies greatly the design but also enables rapid prototyping and non-nuclear testing. We are expecting to iterate quickly through progressively larger scale tests up to full core.”
NANO Nuclear’s engineering team is preparing to mount insulation, fixtures, and instrumentation to create a single-block demonstration unit, which will eventually scale up to a fully functional demo core assembly. In the next phase, the team will integrate cabling, sensors, and additional structural components to build a fully instrumented demo unit. This will enable the team to gather essential data on heat transfer, material performance, and overall reactor safety margins, facilitating validation of the reactor’s thermal and structural performance and ensuring that the design meets expectations before full-scale assembly.
As well as ZEUS, NANO Nuclear is developing the ODIN microreactor, as well the KRONOS MMR (formerly MMR Energy System) and LOKI MMR (formerly Pylon) reactors which it recently acquired from UNSC following its bankruptcy. In December 2024, NANO Nuclear signed a memorandum of understanding with the US Department of Energy Idaho Operations Office to evaluate the feasibility of siting experimental reactors at Idaho National Laboratory.
