Thermal-Hydraulics Engineer (3671)

Navarro Research and Engineering is recruiting a Thermal-Hydraulics Engineer (3671) in Idaho Falls, ID.

Navarro Research & Engineering is an award-winning federal contractor dedicated to partnering with clients to advance clean energy and deliver effective solutions for complex challenges in the nuclear and environmental fields. Joining Navarro means being a part of an exceptional team committed to quality and safety while also looking for innovative strategies to create value for the client’s success. Headquartered in Oak Ridge, Tennessee, Navarro has active programs in place across the nation for DOE/NNSA, NASA, and the Department of Defense.

Navarro 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 a liquid-metal-cooled reactor. This role requires a strong understanding of system-level thermal-hydraulic behavior, passive safety principles, and experience with advanced modeling tools such as RELAP5-3D, SAM, and subchannel or CFD codes.

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

Responsibilities

• 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 performance 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 software.
• Support development of testing plans and analysis for the Aalo sodium test facility and component-level experiments.
• Collaborate across engineering disciplines to integrate thermal-hydraulic models into safety analyses, component design, control strategies, and system validation.
• Review applicable thermal-hydraulic codes, identify gaps in predictive capability, and recommend improvements aligned with industry advancements.Prepare technical documentation including analysis reports, test plans, and design review packages.

• BS or higher 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.
• Strong proficiency in RELAP5-3D, SAM, TRACE, or similar system codes.
• Experience with subchannel or CFD tools (e.g., CTF, STAR-CCM+, OpenFOAM).
• Familiarity with MOOSE-based applications (e.g., PRONGHORN, BISON) is a plus.
• Proficiency in scripting and data analysis (e.g., Python, MATLAB).
• Experience modeling liquid metal systems and other low Prandtl number systems.
• Strong familiarity with verification and validation requirements for nuclear applications.
• Effective communicator and technical problem solver.
• Comfortable working in fast-paced, multidisciplinary environments.
• Demonstrated ability to document results, lead technical efforts, and meet project milestones.

Due to the nature of the government contract requirements and/or clearances requirements, U.S. citizenship is required.

Navarro is an equal-opportunity employer. All qualified applicants will receive consideration for employment without regard to sex, race, religion, color, national origin, age, disability, veteran’s status, or any classification protected by applicable state or local law.

EEO Employer/Vet/Disabled

• Health Care Plan (Medical, Dental & Vision)
• Retirement Plan (401k)
• Life Insurance (Basic, Voluntary & AD&D)
• Paid Time Off (Vacation & Public Holidays)
• Short Term & Long Term Disability