Thermal Hydraulics Engineer

Aalo Atomics is pioneering a new era in clean energy with factory-fabricated microreactors designed to deliver affordable, scalable, and reliable nuclear power. Our mission is to make nuclear energy globally accessible, starting with the Aalo-1, a 10 MWe reactor leveraging cutting-edge safety, modularity, and efficiency. Based in Austin, TX, we're rapidly growing as we work to deploy the world's first fleet of advanced microreactors. Join us and help revolutionize energy for a sustainable future.

About the role

Aalo Atomics is seeking a Thermal-Hydraulics Engineer to join our nuclear engineering group and play a key role in advancing the thermal-fluid modeling, design, and testing of our liquid-metal-cooled reactor. This role requires deep understanding of system-level thermal-hydraulic behavior, passive safety principles, and advanced modeling tools such as RELAP5-3D, SAM, and subchannel or CFD codes.

The selected candidate will work closely with our core design, systems engineering, and safety analysis teams to develop and implement detailed thermal-fluid models, support component and system testing efforts, and drive performance improvements across design iterations.

What you\'ll do

• Apply nuclear and mechanical engineering principles to design, model, and evaluate thermal-fluid behavior in sodium-cooled reactor systems.
• Develop and maintain steady-state and transient models using RELAP5-3D, SAM, or similar codes to assess system behavior under normal, off-normal, and accident conditions.
• Perform CFD simulations of subchannels and other reactor systems using ANSYS-FLUENT, CTF, STAR-CCM+, or equivalent CFD commercial software.
• Support development of testing plans and analysis for the Aalo sodium test facility and related component-level experiments.
• Work collaboratively across engineering disciplines to integrate thermal-hydraulic models into safety analyses, component design, control strategy, and system validation.
• Review applicable thermal-hydraulic codes, identify gaps in predictive capability, and recommend improvements aligned with industry advancements.
• Support preparation of technical documentation including analysis reports, test plans, and design review packages.

Qualifications

BS+ in Nuclear Engineering, Mechanical Engineering, or related field with a thermal-fluids focus.

3–10 years of experience in thermal-hydraulic modeling and simulation, preferably with sodium or other liquid metal reactors.

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