Staff Mechanical Engineer, Numenor (Reactor)

Valar Atomics•Torrance, CA

About The Position

Valar Atomics seeks a Staff Mechanical Engineer for its Numenor reactor program. The role serves as the technical owner for major mechanical systems within the reactor plant, such as the reactor, control rods, helium pressure boundary, helium services, HVAC, and Citadel. The engineer sets design direction for assigned systems and takes them from concept through build, test, and commissioning on the first unit, then drives them into repeatable, scaled production. The role calls for hands-on technical authority and a hardware-first mentality, while maintaining the rigor and control needed to ensure the design basis is met. Valar Atomics is working to make clean, high-temperature nuclear power scalable for industry, hydrogen, and next-generation manufacturing. The Numenor team owns the entire plant, including the reactor core, helium systems, cooling, plant modules, and Citadel. Its work begins with bringing the first unit to life and aims toward a production line that can deliver reactors faster with each build.

Requirements

Bachelor’s degree in Mechanical Engineering or a related field.
8+ years of mechanical engineering experience on complex hardware, such as pressure systems, heat transfer equipment, mechanisms, or large structures.
Experience as the technical owner of a major system, setting margins and making design decisions.
Experience leading mechanical scope on hardware from concept through build, test, and commissioning.
Strong foundation in stress analysis, thermal design, materials, and pressure vessel and piping codes.
Proficiency in CAD (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 (Section VIII, B31.3).
Design-for-manufacture experience and experience scaling from prototype to series production.
Nuclear industry experience in commercial, defense, or national laboratory settings.
Mechanical PE license.

Responsibilities

Own the mechanical design basis for assigned systems, including requirements, interfaces, margins, materials, and code selection.
Make technical decisions on design acceptability for assigned systems and escalate tradeoffs that affect the broader plant.
Lead design reviews and guide systems through gate decisions from concept to design freeze.
Perform and review stress, thermal, and fluid analyses (FEA and CFD), and set the analysis approach for the team.
Take designs to hardware through procurement specifications, vendor selection and management, factory build, and assembly.
Define test and qualification plans with the V&V team, and support integrated testing and commissioning through first operation.
Design for manufacture and repeatability so each unit builds faster than the last.
Collaborate with systems engineering, safety, IC&E, quality, and supply chain to keep the plant design integrated.
Mentor senior and junior engineers, review their designs, and raise the technical bar across the mechanical team.
Lead root cause investigations on complex hardware issues and establish mechanical design standards and best practices.

Benefits

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
Opportunity to help build and scale transformative energy technology from the ground up