Senior Cfd Engineer Jobs in California (NOW HIRING)

About Valar Atomics

At Valar Atomics, we're redefining what's possible in energy. Our mission is to make clean, high-temperature nuclear power scalable-unlocking abundant energy for industry, hydrogen, and next-generation manufacturing. We are a team of builders, engineers, and operators who believe nuclear energy should be fast to deploy, factory-made, and built for the real world. Our first pilot plant in Orangeville, Utah will demonstrate how advanced nuclear systems and fuel fabrication can power the future. Joining Valar Atomics means becoming part of a company where autonomy, ownership, and impact exist at every level.

The Team 

As part of the Engineering organization, Models & Simulations develops advanced analytical models that support engineering design, performance prediction, and system optimization. The team enables informed decision-making through computational analysis and simulation. 

The Role 

The Senior CFD Analysis Engineer owns delivery of analysis and synthesis of results in the computational fluid dynamics workstream for reactor internals and balance-of-plant systems. The Senior CFD Analysis Engineer leads the development and execution of high-fidelity computational fluid dynamics and thermal-hydraulic simulations that underpin the safety, performance and licensing of our advanced reactor systems. Working within the Modelling & Simulation (ModSim) Engineering Group, the role takes ownership of complex flow and heat-transfer problems - from core-inlet and lower-plenum mixing, fuel-assembly thermal-hydraulics and hot-channel analysis through to passive decay-heat removal and containment behavior. The engineer translates physical problems into defensible Ansys Fluent models, establishes the verification and validation (V&V) basis for those models under nuclear quality requirements, mentors junior analysts, and interprets results into engineering conclusions that designers, safety analysts and regulators can rely on.

Key Responsibilities 

• Plan and perform high-fidelity CFD and conjugate-heat-transfer analyses in Ansys Fluent for reactor thermal-hydraulics, including geometry preparation, meshing strategy, turbulence-model selection, solver set-up, and convergence assessment.
• Establish and document the verification and validation basis for CFD work in accordance with ASME V&V 20, including mesh-convergence (GCI) studies and benchmarking against separate-effects and integral-effects test data.
• Provide and receive boundary conditions across streams - supplying heat-transfer and loss coefficients to the Thermal-Fluid (Flownex) stream, exchanging power/heat-source distributions with Neutronics, and handing thermal/pressure loads to FEA for thermal-stress evaluation.
• Lead technical problem definition, perform independent review/checking of analyses, and produce analysis reports and calculation packages that satisfy NQA-1 / 10 CFR 50 Appendix B documentation and traceability expectations.
• Interface with the thermal-fluid systems (Flownex), structural (FEA), and neutronics teams to build coupled and hand-off multiphysics workflows (e.g., CFD-derived heat-transfer coefficients and thermal maps into structural and systems models).
• Lead technical reviews, set CFD modelling standards and best practices, and mentor mid-level and junior analysts; support regulator and customer technical interactions.
• Develop and standardize CFD methods, templates and best practices, and support the Stream Lead in scoping, estimating and scheduling CFD work across projects.

Basic Qualifications  

• Bachelor's degree (or higher) in Mechanical, Aerospace, or Nuclear Engineering, or a closely related field.
• 8+ years of professional, production-grade CFD analysis experience.

Preferred Skills and Experience 

• Master's degree (or higher) in Mechanical, Aerospace, or Nuclear Engineering, or a closely related field.
• Strong grounding in turbulence modeling (RANS k- / k- SST and scale-resolving LES/DES), conjugate heat transfer, multiphase and species transport.
• Master's degree (or higher) in Mechanical, Aerospace, or Nuclear Engineering, or a closely related field.
• Demonstrated V&V practice (ASME V&V 20, GCI, validation against test data) and uncertainty quantification.
• Experience operating under a nuclear or other regulated quality program (ASME NQA-1, ISO 9001, 10 CFR 50 Appendix B) and exposure to NRC / ASME regulatory environments.
• Reactor thermal-hydraulics domain knowledge (natural circulation, passive cooling, coolant behavior for helium, molten salt or liquid metal) is a strong advantage.
• Scripting/automation (Python, journaling, UDFs) and HPC workflow experience; track record of mentoring and leading technical analysis within a team.
• Working knowledge of coupling CFD with systems codes and structural FEA; exposure to advanced-reactor thermal-hydraulics (HTGR, SFR, MSR, micro-reactors) is a plus.
• Track record of mentoring and leading technical systems analysis within a team.

What We Offer  

• Competitive base salary 
• Equity ownership in a rapidly growing advanced energy company 
• Comprehensive medical benefits 
• Unlimited PTO
• Free daily lunch and dinner provided onsite 
• Generous PPE stipend
• High-impact startup environment with significant ownership and autonomy 
• Opportunities for rapid career growth and internal advancement 
• Direct collaboration with experienced operators, engineers, and industry leaders 
• The opportunity to help build and scale transformative energy technology from the ground up

Equal Employment Opportunity Statement

Valar Atomics is an equal opportunity employer. We consider all qualified applicants without regard to race, color, religion, sex, gender identity, sexual orientation, national origin, age, disability, veteran status, or any other protected status under applicable law.

We are committed to providing a workplace free of discrimination and harassment and will provide reasonable accommodation as required by law.

Applicants must be legally authorized to work in the United States as a U.S. citizen or lawful permanent resident (green card holder).