Senior Mechanical Design Engineer; PCS

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.

The Antares team hails from SpaceX, the White House, the Pentagon, the Department of Energy, MIT, Rigetti Computing, General Atomics, Relativity Space, Ursa Major, and National Laboratories like Idaho, Oak Ridge, Los Alamos, and Savannah River. Antares has raised over $600M in venture capital from top-tier investors and has hundreds of million-dollars on contract with the military services, NASA, and the Department of Energy.

About the Role

As a Mechanical Design Engineer on the Power Conversion System (PCS), you will design the hardware that turns a set of individually developed machines (turbo machinery, motor-generator, recuperator, and primary heat exchanger) into one installed, testable, and operable power plant. Your design scope covers the working-fluid pressure boundary, the structural and layout architecture that carries and aligns the rotating machinery, and the high-temperature hardware that must survive it.

This role resolves what happens between the components: routing, supports, thermal growth, leak-tightness, access, and assembly sequence. You will hold the mechanical arrangement and the pressure budget, work the mechanical interfaces to the major PCS components and to the reactor and safety systems, and carry that hardware from concept through fabrication, assembly, and test. You will support test rig design and instrumentation placement, then take what the data says about component life and performance into the next design revision.

The ideal candidate has taken gas-loop, pressure-boundary, or rotating-machinery hardware from concept through fabrication and test, is comfortable designing to low leak requirements and thermal growth as hard requirements rather than afterthoughts, and does their best work when the requirements are still moving. Experience packaging high-temperature machinery or building first-of-a-kind hardware is a strong differentiator.

Key Responsibilities:

• Own the mechanical arrangement and pressure budget of the Power Conversion System and close the loop with cycle performance on parasitic losses.

• Design the working-fluid pressure boundary including piping, joints, penetrations, and isolation with leak-tightness and pressure retention as first-class requirements of a closed cycle.

• Define the mechanical arrangement, maintenance architecture including skid or module arrangement, supports, anchors, and alignment of the rotating machinery, accounting for thermal growth, machinery loads, safety, transport, and seismic conditions.

• Manage mechanical interfaces to major PCS components, reactor, and safety systems.

• Support test rig design and instrumentation placement. Utilize collected data to improve component life and performance.

• Engineer components for high-temperature and high-stress service using metals and advanced materials, in partnership with materials and structural analysis.

• Perform design-for-manufacturability and assembly assessments, including assembly sequence, access, maintainability, and field installation.

• Work with Mechanical, Electrical, Safety, and Nuclear teams to ensure the designs meet the overall objectives and requirements.

Basic Qualifications:

• Bachelor's degree in Mechanical, Aerospace, or a related engineering discipline

• 5+ years for Senior Engineer, including hands-on CAD, analysis,…