Senior Mechanical Engineer

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…