Senior Mechanical Design Engineer (PCS)

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. 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. We’ve raised over $600M in venture capital and have contracts worth hundreds of millions with the military, 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 integrates individually developed machines (turbomachinery, motor-generator, recuperator, and primary heat exchanger) into one installed, testable, and operable power plant. Your scope includes the working-fluid pressure boundary, structural and layout architecture for rotating machinery, and high-temperature hardware. You will resolve challenges between components: routing, supports, thermal growth, leak-tightness, access, and assembly sequence. You will own the mechanical arrangement and pressure budget, work interfaces with major PCS components, the reactor, and safety systems, and carry hardware from concept through fabrication, assembly, and test. You will support test rig design, instrumentation, and use test data to refine component life and performance.

The ideal candidate has experience taking gas-loop, pressure-boundary, or rotating-machinery hardware from concept through fabrication and test. You are comfortable designing for low leak requirements and thermal growth as hard constraints, and thrive when requirements are still evolving. Experience packaging high-temperature machinery or building first-of-a-kind hardware is a strong differentiator.

Responsibilities

• Own the mechanical arrangement and pressure budget of the Power Conversion System; 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.
• Define the mechanical arrangement, maintenance architecture (skid/module), supports, anchors, and alignment of 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; use test 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 teams.
• Perform design-for-manufacturability and assembly assessments, including assembly sequence, access, maintainability, and field installation.
• Collaborate with Mechanical, Electrical, Safety, and Nuclear teams to ensure designs meet overall objectives and requirements.

Requirements

• Bachelor’s degree in Mechanical, Aerospace, or a related engineering discipline.
• 5+ years of experience (for Senior Engineer) including hands-on CAD, analysis, fabrication support, and test.
• Experience designing pressure-retaining or leak-tight fluid hardware and supporting pressure/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 mechanical interfaces between multiple components integrated into a single assembly.

Preferred Skills & Experience

• Experience in Nuclear, Aerospace, Automotive, Power Generation, Motorsports, or Oil and Gas industries.
• Experience designing to pressure-boundary codes and standards (e.g., ASME B31.3, ASME BPVC Section VIII) and writing/executing pressure and leak test procedures.
• Experience with compressible flow, 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/bellows, and insulation design.
• Experience with skid-mounted or modular plant packaging, system layout, and designing for maintenance access.
• Experience with piping flexibility/stress analysis and 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/sensor placement, and using test data to drive design changes.
• Proficiency with design engineering tools such as NX, ANSYS, 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.

Benefits

We are located in Torrance, CA, in a 322,000 square-foot, brand-new facility featuring large open spaces for collaboration, R&D, and production. The location offers easy access to the 405, 105, and 110 freeways and is at the heart of Los Angeles’ emerging tech ecosystem.

Culture

• Think in Systems: Energy and Defense are complex ecosystems. First principles thinking alone is insufficient. Think probabilistically and act decisively.
• Obsess over the End User: The customer and end user are often not the same. We build globally competitive products by focusing on the end user’s entire interaction with the product lifecycle.
• Be Unconstrained by Convention: Our only limits are the laws of physics. If it were easy, it would have already been done. Never shy away from solutions because they’ve never been tried.
• Go Where the Work Is: Never miss a chance to meet customers, users, or stakeholders face-to-face. Teams are built in person, and we maximize our time together.
• Operate in the Grey: Embrace nuance in pursuit of truth. Question every fundamental assumption.

Pay

Mechanical Design Engineer II: $145,000 – $185,000

To conform to U.S. Government export regulations, applicants must be U.S. citizens, lawful permanent residents, refugees, or asylees, or eligible for required authorizations from the U.S. Department of State.