Senior Mechanical Engineer

Hexium is an energy technology company focused on advancing isotope enrichment through Atomic Vapor Laser Isotope Separation (AVLIS), a laser-driven process that selectively ionizes and separates specific isotopes from a vaporized metal stream. The company is beginning with lithium enrichment and aims to expand into a broad range of isotopes critical for clean energy, nuclear medicine, and advanced industrial applications. Hexium positions itself as a key enabler of the nuclear renaissance by providing enriched materials needed for next-generation nuclear reactors and related technologies. Hexium's mission aligns with sustainability and climate goals by developing a cleaner alternative to conventional isotope separation methods such as centrifuge-based or chemical separation processes. Their AVLIS approach produces no hazardous waste, eliminates the need for complex mechanical systems or costly chemical agents, and offers a compact, scalable footprint. This low-waste profile makes the technology particularly relevant for green energy supply chains, including the production of lithium isotopes used in advanced nuclear fuel cycles and battery-related applications. What differentiates Hexium is its patent-pending modernization of AVLIS technology, which was previously de-risked at pilot scale through over two billion dollars in U.S. Department of Energy investment. By leveraging existing supply chain infrastructure and modern laser designs, Hexium aims to achieve commercially viable capital and operating costs. The platform's adaptability across multiple isotopes positions the company as a flexible supplier for high-impact sectors at the intersection of nuclear energy, medicine, and industrial innovation.

Hexium is modernizing Atomic Vapor Laser Isotope Separation (AVLIS), a laser-based isotope enrichment technology originally developed and demonstrated at Lawrence Livermore National Laboratory (LLNL). We are advancing AVLIS into a scalable, industrial-grade enrichment platform designed to strengthen domestic energy infrastructure, industrial resilience, and national security. 

Role

We're hiring a Senior Mechanical Engineer to lead the translation of decades of AVLIS research and development into modern, manufacturable hardware. Initially based on-site at Lawrence Livermore National Laboratory (LLNL) in Livermore, CA, you'll work through legacy technical records to identify the most relevant mechanical designs, reconstruct them as modern 3D assemblies, and identify gaps requiring further engineering. You'll collaborate with national laboratory scientists and engineers as needed to resolve technical questions and inform the modernized design.

From there, you'll advance designs through simulation, prototype hardware, and test fixtures, while serving as a mechanical design authority for Hexium's initial prototype and pilot systems. This is foundational engineering work that will bridge national laboratory R&D with the systems needed to advance AVLIS toward commercial application.

As the program progresses, this role will transition to a Hexium production facility and will require relocation.

Key Responsibilities

• Review and assess legacy AVLIS mechanical designs and technical records at a DOE national laboratory, working within required classified-handling procedures
• Own mechanical design of chamber and vacuum systems, including all system interfaces
• Apply vacuum system design to materials compatibility selection, outgassing mitigation, and contamination control
• Convert legacy designs into modern 3D CAD assemblies and validate them via thermal/structural simulation
• Work directly with national laboratory scientists and engineers to close technical design gaps
• Collaborate with Hexium's Integration Team on prototype procurement and testing requirements
• Qualify vacuum suppliers and custom equipment fabricators
• Define facility and utility interface requirements for prototype and pilot systems
• Partner with Nuclear Safety on design compliance

Required Qualifications

• 6+ years of mechanical engineering experience, including vacuum system design and/or precision mechanical hardware
• Bachelor's degree in Mechanical Engineering or closely related field
• Proficiency in 3D CAD (SolidWorks, Creo, or similar)
• Must currently hold an active DOE Q clearance or active DOD Top Secret clearance, or have held DOE Q / DOD Top Secret clearance within the past 18 months
• Must be a U.S. Person (required for access to export-controlled technical data)
• Willingness to work on-site full-time at Lawrence Livermore National Laboratory initially, with required relocation to Hexium's production facility (location not yet determined) as the program progresses

Preferred Qualifications

• Experience with specialty alloys and refractory metal fabrication
• Experience with high-temperature vacuum processes
• FEA/thermal simulation experience
• Background in safety-critical hardware (aerospace, nuclear, defense)

Physical Requirements

• Extended periods reviewing physical archival documents and fine-detail technical drawings, requiring sustained close visual focus
• Fine motor skills and dexterity for precision component assembly and inspection
• Ability to work in confined spaces around vacuum hardware
• Occasional lifting up to 50 lbs
• Extended periods standing/moving within a lab environment

Work Environment 

On-site at a DOE national laboratory in Livermore, CA, with standard site security and classified-handling protocols. Role will transition to a separate Hexium production facility as the program scales.

Benefits

• Stock Options
• Paid Time Off
• 401(k) Matching
• Medical, Dental, Vision insurance
• HSA & FSAs

 

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E-Verify: Hexium Inc. participates in E-Verify. All new hires are required to complete the I-9 employment eligibility verification form and provide documentation to confirm their identity and authorization to work in the United States.

Screening: Employment is contingent upon successful completion of a background check.

Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job. 

Hexium Inc. is an Equal Employment Opportunity Employer. We provide equal employment opportunities to all employees and applicants for employment and prohibit discrimination and harassment of any type without regard to race, color, religion, age, sex, national origin, disability status, genetics, protected veteran status, sexual orientation, gender identity or expression, or any other characteristic protected by federal, state, or local laws. Hexium Inc. is committed to ensuring equal access and providing reasonable accommodations for applicants and employees with disabilities upon request. If reasonable accommodation is needed to participate in the job application or interview process,  please contact Hexium’s Human Resources at [email protected].