Thermal Hydraulics Engineer

About the CompanyWe’re partnering with a well-funded, early-stage nuclear energy startup 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.Role OverviewWe 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 ResponsibilitiesLead accident scenario modeling and safety analysis using system-level codesAnalyze thermal-hydraulics performance under steady-state and transient conditionsPerform CFD modeling and simulation to support reactor and system design effortsCollaborate cross-functionally with reactor design, systems, and safety teamsContribute to the development and validation of modeling methodologiesSupport design decisions through quantitative simulation insightsRequired QualificationsProfessional experience with system codes and accident modeling tools (RELAP, MELCOR, or equivalent)Strong understanding of thermal-hydraulics and fluid dynamics principlesProfessional engineering experience applying CFD and thermal-fluid analysisHands-on experience with CFD tools (Star-CCM+ preferred; other packages acceptable)Ability to work onsite in a fast-paced, startup environmentDemonstrated ability to learn new technical domains and solve complex engineering challengesPreferred / Nice-to-Have QualificationsIndustry experience in nuclear engineeringExperience with nuclear-specific CFD applicationsExperience coupling CFD and FEA analyses for thermal-mechanical design challengesExperience modeling heat exchangers, steam generators, or similar thermal-fluid systemsExposure 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 processesFamiliarity with cost modeling or techno-economic analysisBroader systems-level understanding of reactor designExperience working in startup, high-growth, or fast-paced engineering environmentsExperience with both computational modeling and experimental/testing programsWhat We're Looking For (Culture & Mindset)Strong communicator who collaborates effectively across highly technical teamsProven grit, resilience, and determination—comfortable tackling ambiguous, high-difficulty problemsStrong interest in working on first-of-a-kind (FOAK) hard-tech projectsCurious, continuous learner who can quickly develop expertise in new technical areasBuilder mentality: takes ownership, moves with urgency, and thrives in early-stage environmentsCommitted to technical excellence while balancing speed, execution, and practical engineering outcomesMotivated by the opportunity to help reshape the future of energyCompensationCompetitive salary based on years of experienceHealthcare & dental fully covered by the company. Vision Available.EquityRelocation assistance possible