Senior Mechanical Design Engineer - Cover Gas Systems

About Us

At Antares, our long-term mission is to make clean energy abundant from Earth to the Asteroid Belt. We’re fueled by the belief that advanced nuclear energy can strengthen our military, solve the climate crisis, elevate global living standards, and expand humanity's presence in outer space. To achieve our mission, we’re building mass‑producible, inherently safe, deployable microreactors that can be used terrestrially, underwater, and in space.

Formed in 2023, the Antares team hails from Space

X, The White House, MIT, Rigetti Computing, The Air Force, General Atomics, Relativity Space, Ursa Major, and National Laboratories like Los Alamos, Idaho, and Oak Ridge. Antares has raised over $130M in venture capital from top‑tier investors and has over $13M in government funding.

As the Responsible Engineer (RE) for the Cover Gas System, you will lead the design, development, testing, and validation of mechanical systems that monitor fission products released from nuclear fuel and maintain an inert reactor core environment. You will own the mechanical architecture of the system, sizing and integrating components that interface with electrical and software subsystems, and collaborating closely across disciplines to define requirements, documentation, and verification plans.

The ideal candidate has a strong background in fluid system design, particularly involving compressible flow, and experience developing hardware for demanding environments. Familiarity with radiation detection technologies (e.g., scintilla tors, Geiger‑Müller counters, or solid‑state detectors) is a strong differentiator.

• Design, build, and test the reactor’s cover gas system, hardware, assemblies and detectors.
• Concept and develop custom fluid‑dynamic features to support fission product detection and inert environment retention.
• Define design criteria, requirements, system architecture, and verification/validation test plans.
• Collaborate closely with cross‑functional teams across thermal, structural, neutronics, controls, and simulation disciplines.
• Engineer components for high‑temperature, high‑stress, and radiation environments using metals, ceramics, and other advanced materials.
• Perform design‑for‑manufacturability (DFM) assessments and execute tradeoffs across performance, cost, schedule, and risk.
• Document technical decisions and tradeoffs, and present recommendations to senior leadership.

• Bachelor's degree in engineering
• 5+ years of experience in full‑cycle design engineering roles, including hands‑on CAD, analysis, build, and test
• Experience designing, sizing, and integrating fluid systems, preferably involving compressible flow
• Experience performing and interpreting computational fluid dynamics (CFD) analyses.

• Experience in the Nuclear, Aerospace, or Oil and Gas industries
• Experience in a demanding fast‑paced development environment
• Experience with design engineering tools such as NX, ANSYS or Femap, and other product lifecycle software
• Experience with engineering scripting languages such as Python and MATLAB
• Experience working with radiation detectors

• Ability to work long hours and weekends as necessary to support critical milestones

• The Antares HQ is located in Torrance, CA in a 145,000 square foot, brand new facility featuring large open spaces for team collaboration, R&D, and production, as well as easy access to the 405, 105, and 110 freeways. Our HQ is in the heart of Los Angeles' vibrant emerging tech ecosystem alongside many other high growth startups and enterprises.

At Antares, we like to specifically tie each role to our founding document’s set of values–here are the top five cultural values we think you should believe at your core to be successful:

• Think in Systems - Energy and Defense are complex ecosystems with numerous stakeholders with competing priorities, conflicting policies, perverse incentives, and emergent and path‑dependent properties. First principles thinking alone is insufficient. Think probabilistically and then take action. “If you want to be certain, then you are apt to be…