Mechanical Design Engineer

We are seeking an experienced Mechanical Design Engineer to join our in-person team in Austin Texas.

Subcritical Systems Inc. is a funded startup based in Austin, Texas dedicated to bringing the energy amplifier concept to the United States for safe generation of electrical power. Using a particle accelerator to sustain fission of nuclear fuel in a subcritical core, our innovative approach aims to transform energy production. The founding team is comprised of successful entrepreneurs with a history of building cutting-edge technology companies and scientists from US national labs with deep experience in energy amplifier technologies.

Subcritical Systems is venture-backed and actively hiring to expand its dynamic team, working towards licensing, regulatory submissions and construction of its first energy amplifier. More information is available at

We are seeking a creative and experienced Mechanical Design Engineer 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.

We cannot accept candidates who require visas/sponsorship at this time.

• Develop conceptual and detailed mechanical designs for components, assemblies, and 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 Solid Works (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

• Bachelor’s degree in Mechanical Engineering with 8+ years of industry experience supporting mechanical engineering projects
• Proficiency with NX, Solid Works, Solid Edge, Pro-E, or similar 3D CAD tools (NX preferred)
• Proficiency in Finite Element Analysis
• Ability to create, revise, and check mechanical drawings using GD&T per ASME Y14.5
• Familiarity with machining, metalworking, 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

• 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

• A high-impact role where your work has real-world application in addressing the nation’s energy challenges via the development of truly forward-looking approaches and technology.
• Competitive compensation commensurate with experience and technical expertise.
• Comprehensive healthcare insurance.
• The chance to work alongside world-class entrepreneurs and well-known scientific leaders.
• An opportunity to work in a fast-paced startup environment.
• The opportunity to live in the thriving, dynamic community of Austin, Texas, with all the city has to offer.