Thermal Hydraulics Engineer

About the Company We’re partnering with a well-funded, early-stage nuclear energy startup based in San Francisco . The company is focused on developing next-generation, compact reactor systems designed for scalable, cost-predictable deployment across large energy applications such as data centers, industrial heat, and grid-scale power. Backed by significant private funding and operating in a true builder/startup environment, the team is mission-driven, fast-moving, and deeply committed to tackling complex, first-of-a-kind (FOAK) engineering challenges. This is an opportunity to join at an early stage and play a key role in shaping both the technology and the organization. This is a remote role with travel as needed. Role Overview We are seeking a Thermal Hydraulics Engineer with nuclear industry experience to support the modeling and simulation of advanced reactor systems, including normal operation and transient/accidental scenarios. This individual will contribute to the design, analysis, and optimization of high-performance nuclear systems in a highly collaborative, hands-on startup environment. Key Responsibilities Lead accident scenario modeling and safety analysis using system-level codes Analyze thermal-hydraulics performance under steady-state and transient conditions Perform CFD modeling and simulation to support reactor and system design efforts Collaborate cross-functionally with reactor design, systems, and safety teams Contribute to the development and validation of modeling methodologies Support design decisions through quantitative simulation insights Required Qualifications Professional experience with system codes and accident modeling tools (RELAP, MELCOR, or equivalent) Strong understanding of thermal-hydraulics and fluid dynamics principles Professional engineering experience applying CFD and thermal-fluid analysis Hands-on experience with CFD tools (Star-CCM+ preferred; other packages acceptable) Ability to work onsite in a fast-paced, startup environment Demonstrated ability to learn new technical domains and solve complex engineering challenges Preferred / Nice-to-Have Qualifications Industry experience in nuclear engineering Experience with nuclear-specific CFD applications Experience coupling CFD and FEA analyses for thermal-mechanical design challenges Experience modeling heat exchangers, steam generators, or similar thermal-fluid systems Exposure to core design / reactor physics tools (CASMO, SIMULATE, or equivalent) Experience with fuel performance modeling (FRAPCON, BISON, or similar) Experience supporting work performed under NRC regulatory frameworks or licensing processes Familiarity with cost modeling or techno-economic analysis Broader systems-level understanding of reactor design Experience working in startup, high-growth, or fast-paced engineering environments Experience with both computational modeling and experimental/testing programs What We're Looking For (Culture & Mindset) Strong communicator who collaborates effectively across highly technical teams Proven grit, resilience, and determination —comfortable tackling ambiguous, high-difficulty problems Strong interest in working on first-of-a-kind (FOAK) hard-tech projects Curious, continuous learner who can quickly develop expertise in new technical areas Builder mentality: takes ownership, moves with urgency, and thrives in early-stage environments Committed to technical excellence while balancing speed, execution, and practical engineering outcomes Motivated by the opportunity to help reshape the future of energy Compensation Competitive salary based on years of experience Healthcare & dental fully covered by the company. Vision Available. Equity