Senior Mechanical Design Engineer (PCS)

About the company

Antares is a nuclear power startup developing small modular reactors (SMRs) using TRISO fuel for deployment at U.S. military bases.

About this role

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 (turbomachinery, 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, fabrication support, and test - Experience designing pressure-retaining or leak-tight fluid hardware and supporting pressure and leak verification - Experience releasing production-intent mechanical drawings and models for fabrication, including GD&T and tolerance stack-up - Experience designing hardware for elevated-temperature or high-stress service, including material selection - Experience working the mechanical interfaces between multiple components integrated into a single assembly Preferred Skills & Experience: - Experience in the Nuclear, Aerospace, Automotive, Power Generation, Motorsports, or Oil and Gas industries - Experience designing to pressure-boundary codes and standards such as ASME B31.3 or ASME BPVC Section VIII, and writing or executing pressure and leak test procedures - Experience with compressible flow, and with flow network or pressure-drop modeling to close a system pressure budget - Experience packaging or integrating rotating machinery, including alignment, supports, and machinery loads - Experience with high-temperature systems: thermal growth accommodation, expansion joints and bellows, and insulation design - Experience with skid-mounted or modular plant packaging, system layout, and designing for maintenance access - Experience with piping flexibility and stress analysis, and with structural FEA of supports and anchors - Experience with high-temperature metals and advanced materials, including creep-limited design in stainless steels or nickel superalloys - Experience designing to transport and seismic load cases - Experience supporting test rig design, instrumentation and sensor placement, and using test data to drive design changes - Experience with design engineering tools such as NX, ANSYS or Femap, and other product lifecycle software - Experience commissioning first-of-a-kind hardware and supporting bring-up and troubleshooting - Experience in a demanding, fast-paced development environment Salary Range: - Mechanical Design Engineer II - $145,000 - $185,000 Location: - We are located in Torrance, CA in a 322,000 square foot, brand new facility featuring large open spaces f