Senior Mechanical Design Engineer

ABOUT SUBCRITICAL SYSTEMS

Subcritical Systems, Inc. is a venture-backed startup in Austin, Texas building the accelerator driven systems and the only US commercial manufacturer of accelerator cavities. What Space X did for rockets, we plan to do for accelerator cavities and commercialize across applications of power production, medical isotopes, semiconductors and waste transmutation.

We are in the process of building the Energy Amplifier — a novel nuclear fission system in which a particle accelerator drives a subcritical core, making meltdown physically impossible for clean power production. Due to its inherent safety, our system has a more streamlined licensing process. Our founding team includes successful entrepreneurs with a track record of building several multibillion dollar companies in deep-tech, and scientists who were leading U.S. national labs with deep experience in accelerator & nuclear technologies.

We are actively hiring to expand our team as we work toward licensing, regulatory submissions, and construction of our first energy amplifier. More information is available at subcritical.com.

ROLE SUMMARY

We are seeking a creative and experienced Mechanical Design Engineer with 10+ years of experience and demonstrated expertise in structural finite element analysis to join our growing team in a full-time, on-site role in Austin, TX. In this role you will work closely with the engineering and scientific teams to develop designs for subcritical assembly and particle accelerator components and systems. This is an ideal role for an ambitious, creative and hard-working Engineer who wants to use their expertise to transform the energy system and in so doing change the world.

KEY RESPONSIBILITIES

• Develop conceptual and detailed mechanical designs for components, assemblies, and systems.
• Perform structural finite element analyses of mechanical systems
• Translate functional requirements, specifications, and performance targets into manufacturable designs.
• Create and manage 3D CAD models and 2D fabrication drawings using software such as NX or SolidWorks (NX preferred).
• Conduct engineering calculations and simulations (e.g., stress, thermal, vibration, fatigue, or CFD).
• Generate assembly models, weldment drawings, and detailed part documentation.
• Use analytical tools or finite-element packages to validate design integrity.
• Select appropriate materials, coatings, and surface treatments for performance and corrosion resistance.
• Develop fabrication and assembly specifications, bill of materials and procurement packages.
• Prepare engineering documentation, including design reports, calculations, and interface control documents.
• Manage fabrication tasks and fabrication procurements.
• Support build-out of in-house manufacturing and testing systems
• Ensure compliance with applicable codes, standards, and safety requirements.
• Apply GD&T, DFM, and DFA practices to ensure drawings are clear, manufacturable, and accurate
• Interface with suppliers, vendors, and fabrication shops to communicate drawing requirements and resolve build issues

QUALIFICATIONS

Required

• 10+ years of experience in mechanical design engineering or a comparable role
• Proficiency in Structural Finite Element Analysis (FEA)
• Bachelor's degree in Mechanical Engineering
• Proficiency with NX, SolidWorks, Solid Edge, Pro-E, or similar 3D CAD tools (NX preferred)
• Ability to create, revise, and check mechanical drawings using GD&T per ASME Y14.5
• Familiarity with machining, metalworking, and welding
• Experience applying design-for-manufacturing (DFM) and design-for-assembly (DFA) principles to support engineering intent
• Ability to translate engineering requirements into detailed drawing packages
• Experience working in a team environment with scientists, engineers and technicians
• Strong work ethic, resilient, able to work in a fast-paced collaborative environment

Preferred

• Extensive familiarity with NX
• Master's degree in Mechanical Engineering
• Extensive familiarity with fabrication processes (machining, welding, forming)
• Familiarity with revision control, configuration management, and drawing release workflows
• Hands-on experience assembling mechanical prototypes, fixtures, or test jigs

BENEFITS

We offer health, dental, and vision insurance.

LOCATION & WORK POLICY

This role is fully in person in Austin, Texas. Our facility is located next to Austin Airport.