US-based Aalo has completed its Preliminary Design Review for its experimental reactor, Aalo-X, with more than 20 independent reviewers from the Department of Energy (DOE), Nuclear Regulatory Commission (NRC) and others.
The Aalo-X reactor is an experimental, extra-modular reactor (XMR) that uses sodium as a coolant and is fueled by low-enriched uranium dioxide. The Aalo-X is a full-scale, 10 MWe experimental power plant that bridges the gap between smaller microreactors and traditional small modular reactors (SMRs). The reactor and all its plant components are factory-built in modules for rapid on-site assembly.
The design incorporates physics-based, passive safety mechanisms instead of relying on complex, expensive engineered safety systems. According to Aalo, this leverages the properties of the liquid metal coolant and fuel to ensure safety and enhance thermal efficiency. The Aalo-X is designed to be air-cooled, enabling flexible siting options, including direct, on-site deployment for facilities such as data centres.
The reviewers listened to two days of presentations, asked questions and gave feedback on how to improve operations to exceed regulatory standards for quality and safety. Aalo-X is being authorised by DOE, and regulators from NRC attended the review as observers.
Dr Yasir Arafat, Chief Technology Officer, presented the overall scope of Aalo-X and how it relates to Aalo’s reactor development programme. “Building provably safe nuclear reactors to exacting regulatory standards is a mammoth challenge. We are lucky to have an unbelievably talented team taking on every dimension of this task, he said.
Aalo-X was selected by DOE to participate in President Trump’s Nuclear Reactor Pilot Program and is aiming to complete construction and to achieve criticality by July 2026. In the past few months, the Aalo-X has secured official site allocation from DOE’s Idaho Operations Office (DOE-ID), and received an Environmental Assessment Determination from the DOE, which expedites the environmental review process. However, it remains to be seen. whether a sodium-cooled reactor can go from preliminary design to criticality in one year.
