Thermal Hydraulics Engineer

About the Company

We’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 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
• Relocation assistance possible