Senior Mechanical Engineer, Numenor (Reactor)

Valar Atomics•Torrance, CA

About The Position

Valar Atomics is seeking a Senior Mechanical Engineer for its Numenor reactor program. The role owns the design, build, and test of mechanical subsystems within the reactor plant, including the reactor, control rods, helium pressure boundary, helium services, HVAC, and Citadel. The engineer will take hardware from concept through build, test, and commissioning on the first unit, then help move it into repeatable, scaled production. The role is hands-on and hardware-focused, with responsibility for ensuring the design basis is met. The engineer will own assigned subsystem mechanical design from requirements and concept through detailed design and design freeze; perform and review stress, thermal, and fluid analyses; develop CAD models and drawings; and present designs at reviews. The role also involves procurement specifications, vendor management, factory build and assembly, component and integrated testing, and commissioning support. Close collaboration with systems engineering, safety, IC&E, quality, and supply chain is required. The engineer will mentor junior engineers, contribute to design standards and configuration management, and lead hardware root-cause investigations and corrective actions. Valar Atomics is developing clean, high-temperature nuclear power for industry, hydrogen, and next-generation manufacturing. The Numenor team owns the plant, including the reactor core, helium systems, cooling, plant modules, and Citadel, with the goal of bringing the first unit to life and building a production line that can deliver reactors at increasing speed.

Requirements

Bachelor’s degree in Mechanical Engineering or a related field.
At least 5 years of mechanical engineering experience on complex hardware, such as pressure systems, heat transfer equipment, mechanisms, or large structures.
Proven track record taking hardware from design through build and test.
Strong foundation in stress analysis, thermal design, materials, and pressure vessel and piping codes.
Proficiency in CAD software such as SolidWorks, Creo, NX, or similar, and engineering drawing standards.

Nice To Haves

Master’s degree in Mechanical Engineering or a related field.
Experience with high-temperature, high-pressure systems, such as pressure vessels, heat exchangers, and piping.
First-of-a-kind hardware experience in aerospace, power generation, oil and gas, or defense.
Experience with helium or other gas systems, including sealing, leak tightness, and rotating equipment.
Experience with precision mechanisms and actuators, including their qualification testing.
Working knowledge of ASME pressure vessel and piping codes, including Section VIII and B31.3.
Experience with design for manufacture and scaling from prototype to series production.
Nuclear industry experience in commercial, defense, or national laboratory settings; this is a plus, not a prerequisite.

Responsibilities

Own mechanical design of assigned subsystems from requirements and concept through detailed design and design freeze.
Perform and review stress, thermal, and fluid analyses, including FEA and CFD, to validate margins, materials, and code compliance.
Develop 3D CAD models, assemblies, and drawings, applying GD&T and tolerance analysis.
Present designs at design reviews and drive resulting actions to closure.
Take designs to hardware through procurement specifications, vendor management, factory build, and assembly.
Plan and execute component and integrated testing with the V&V team, and support commissioning through first operation.
Design for manufacture and repeatability so each unit can be built faster than the last.
Coordinate with systems engineering, safety, IC&E, quality, and supply chain to keep the plant design integrated.
Mentor junior engineers and contribute to design standards, documentation, and configuration management.
Lead root-cause investigations and drive corrective actions on hardware issues.

Benefits

Competitive base salary
Equity ownership
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
Opportunity to help build and scale transformative energy technology from the ground up