US-based Aalo Atomics has submitted a pre-application regulatory engagement plan (REP) with the US Nuclear Regulatory Commission (NRC) for its Aalo-1 microreactor. The REP, which details the planned pre-licensing application interactions with NRC can reduce regulatory uncertainty and add predictability to licensing advanced technologies. There is no regulatory requirement for a REP and the level of detail a prospective applicant includes are entirely voluntary and should be agreed upon in discussions between the applicant and NRC staff.
In May, Aalo Atomics said it had completed the conceptual design of the Aalo-1 – a factory-fabricated 10 MW sodium-cooled microreactor that uses uranium zirconium hydride (UZrH) fuel. Also in May, Aalo signed a Siting Memorandum of Understanding (MOU) with the Department of Energy (DOE) – the first step towards deploying the first Aalo-1 reactor at the Idaho National Laboratory (INL) site in Idaho.
Aalo said that, with the MOU in place, focus on concluding a real property agreement with DOE, selecting a specific parcel of land to site the Aalo-1 reactor. “This step will involve extensive collaboration with INL and local stakeholders to ensure the chosen site meets all technical and environmental requirements.” Following land selection, environmental impact assessments will follow. “This effort will set the precedent for efficient siting of future Aalo-1 reactors throughout the nation.”
Aalo also announced plans to construct a full-scale, non-nuclear prototype of the Aalo-1 reactor following completion of its conceptual design. “The prototype will serve as an important step in testing and refining our technology, ensuring that Aalo-1 meets its technical, regulatory, and economic targets.”
According to Aalo, its technology promises safety through two key factors. Firstly, the reactor uses UZrH fuel, also used in TRIGA research reactors developed by General Atomics in the 1950s and safely used at university campuses throughout the US. “TRIGAs were designed to work with water coolant and fairly low temperature environments, but experiments suggest this fuel works well at higher temperatures, too. Aalo’s approach is to pair this inherently safe fuel with a low pressure, high temperature coolant: sodium. Safety is improved by using a low-pressure coolant and creating a negative feedback loop in the power level with UZrH.”
Aalo’s reactors “strike the optimal balance between economies of numbers, and economies of scale. Costs are reduced through factory assembly of reactor modules. Construction time is reduced through simple on-site assembly. This reduces compounding interest that has inflated the cost of traditional nuclear.”
Metallic coolant and fuel unlocks optimal economics. “Liquid metal is able to extract heat from the reactor core much faster than water or gas. This means Aalo reactors can produce up to 10x more energy than competing technologies of a similar size.”
In 2023 Aalo raised $6.26 million in seed money and began design of its reactor based on INL’s Microreactor Applications Research Validation and EvaLuation (MARVEL) project – a liquid-metal cooled microreactor with a rated peak capacity of 100 kWt. INL says it is based on existing technology and using off-the-shelf components where possible. The philosophy behind the MARVEL test bed is to allow for rapid construction to allow demonstrations of microreactor technology and applications promptly. Aalo says it recruited top leadership from MARVEL programme.
According to its website, in 2025 Aalo expects to approach commercial readiness, to complete full-scale non-nuclear prototype testing, and begin procurement for commercial Aalo-1 reactor materials. In 2026 Aalo aims to have its final design 90% complete.
Following submission of its REP, Aalo said: “By setting expectations, building trust, and addressing the NRC’s questions and concerns early on, we aim to create a safe, socially acceptable, and commercially viable Aalo-1 reactor for the Idaho Nuclear Project.” The company said that initially, this project will feature seven independent Aalo-1 reactors, potentially expanding to an additional seven reactor units.
“Once we get the green light and start construction, this will be the highest number of nuclear reactors at a single site in the US – a game-changer for small reactor clusters,” Aalo said. “This plant will help our partner utility provide affordable, reliable electricity to meet current and future energy and sustainability needs. We aim to have it up and running by 2029.”
In December 2023, Aalo was among the first FY2024 recipients awarded vouchers by DOE’s Gateway for Accelerated Innovation in Nuclear (GAIN) initiative. GAIN gives access to the DOE’s R&D facilities and infrastructure to support the cost-effective development of innovative nuclear energy technologies. Awardees are responsible for a minimum 20% cost-share, which could be an in-kind contribution. Aalo was awarded GAIN vouchers to collaborate with INL to evaluate modelling and simulation capabilities for the fuel and core system of the Aalo-1 microreactor.
