Nuclear Engineer III​/IV; Thermal Hydraulics Engineering Madison, WI

Nuclear Engineer III (Thermal Hydraulics)

About Us

We’re pioneering the next generation of nuclear technology to deliver safe, scalable, and sustainable energy. Our team is small, fast-moving, and mission-driven —combining deep technical expertise with a startup’s sense of urgency. As we grow, we’re designing the systems that will redefine what nuclear power can do for the world.

Nuclear Engineer III (Thermal Hydraulics)

Madison, WI

Full‑Time

As an emerging leader in nuclear engineering, our startup is developing revolutionary reactor technology to secure safe and abundant energy for future generations. We are seeking a highly skilled Nuclear Engineer III (Thermal Hydraulics) to join our dynamic team and contribute to the design and development of next‑generation nuclear reactors.

Position Overview:

The Nuclear Engineer III (Thermal Hydraulics) will contribute to the design, analysis, and optimization of molten salt nuclear reactor systems. The ideal candidate will have a strong background in molten salt systems, proficiency with industry‑standard design software, and a proactive, self‑starting attitude. This role requires innovative thinking, technical expertise, and a commitment to advancing safe and sustainable nuclear energy solutions.

• Conduct thermal‑hydraulic design and analysis of the salt loops, storage tanks, heat exchangers and power conversion, including start‑up, steady‑state, and transient conditions.
• Develop specifications and support design of critical components heat exchangers, pumps, valves, measurement systems and fluid transfer systems.
• Help design and run the integration of the reactor loops with heat rejection and power conversion systems as required.
• Develop and maintain thermal‑hydraulic models using appropriate tools.
• Support safety analyses for licensing‑basis events and beyond‑design‑basis events including loss‑of‑flow, loss‑of‑heat‑sink, reactivity transients, and freeze/thaw scenarios.
• Specify and support selection of instrumentation relevant to thermal‑hydraulic performance monitoring.
• Oversee and conduct thermal‑hydraulic testing, including separate‑effects tests, integral tests, and validation experiments for model benchmarking.
• Contribute to design requirements, safety classification, and functional specifications in compliance with nuclear standards.
• Perform uncertainty quantification, sensitivity studies, and validation & verification (V&V) of thermal‑hydraulic models.
• Support licensing efforts by preparing technical reports, responding to regulatory questions, and providing thermal‑hydraulic justification for design decisions.
• Help to develop strategy for team growth: define roles, recruit, mentor, and build a high‑performing thermal hydraulics group as the project matures.
• Maintain comprehensive documentation, including design basis reports, calculation packages, and configuration management, including QA documentation of testing.

• Bachelor’s degree in Nuclear Engineering, Mechanical Engineering, Chemical Engineering, or a closely related field. Master’s degree or PhD strongly preferred.
• Minimum 10 years of direct experience in thermal‑hydraulic analysis and design, with at least 5 years in safety‑critical or highly regulated industries.
• Deep expertise in:
  • Thermal‑hydraulic phenomena in liquid‑cooled systems (single‑ and multi‑phase flow, heat transfer, natural circulation, transient analysis).
  • System‑level and CFD modeling tools relevant to nuclear or high‑temperature applications.
  • Nuclear safety analysis methods and regulatory requirements for thermal‑hydraulic performance.
  • Experimental design and interpretation of thermal‑hydraulic test data.
  • Instrumentation challenges in extreme environments.
• Proven ability to lead technical efforts, develop and execute test programs and build teams.
• Strong understanding of nuclear quality assurance.
• Excellent analytical, problem‑solving, and communication skills.
• U.S. citizenship or permanent residency required.

• Direct experience with molten salt reactors (MSRs), fluoride salts, or other Gen IV advanced reactor concepts.
• Hands‑on experience with molten salt…