Thermo-Mechanical Engineer II

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 Thermo-Mechanical Design Engineer, you will play a key role in developing, designing, qualifying, and deploying advanced heat exchanger systems for cutting-edge energy applications. You will work closely with Responsible Engineers and cross-functional teams to mature designs from concept through production. The ideal candidate will bring strong mechanical design fundamentals, thermal engineering knowledge, and hands-on hardware development experience to deliver reliable, high-performance heat exchangers and associated piping systems for next-generation energy applications.

Roles & Responsibilities

Perform mechanical design, modeling, and analysis of heat exchanger systems, ensuring thermal performance, structural integrity, and compatibility with system interfaces.

Design and analyze heat exchanger inlet/outlet piping, manifolds, and associated mechanical interfaces, ensuring compatibility with system performance and installation requirements.

Evaluate thermal stresses, differential thermal expansion, pressure loads, piping flexibility, and mechanical loads transmitted between heat exchangers, piping, and supporting structures.

Support development of manufacturing methods, including material selection, fabrication processes, joining techniques, and assembly of heat exchanger and piping components.

Design and support development of test articles, test stands, and procedures to validate thermal performance, structural integrity, and operational life.

Coordinate with internal teams and external stakeholders to translate system requirements into manufacturable and reliable hardware products.

Support the design and integration of piping connections, flanges, weld joints, supports, and other fluid-system components, considering manufacturability, assembly, inspection, and maintenance.

Define operating limits and performance envelopes for heat exchanger systems.

Investigate hardware failures, identify root causes, and rapidly implement design improvements to enhance performance and reliability.

Basic Qualifications

Bachelor's degree in Mechanical Engineering, Aerospace Engineering, Nuclear Engineering, or a related physics-based field.

2+ years of experience in mechanical or thermal engineering, preferably involving heat exchangers, pressure-containing equipment, or high-temperature systems.

Demonstrated experience with mechanical CAD design and engineering analysis tools (e.g., SolidWorks, NX, ANSYS, COMSOL).

Understanding of heat transfer fundamentals, fluid mechanics, thermal stresses, and structural mechanics.

Understanding of piping and pressure-containing component design, including pressure loads, thermal expansion, and mechanical interfaces.

Knowledge of materials science as it applies to material selection, thermal properties, and structural performance.

Preferred Skills and Experience

Master's degree in Mechanical Engineering, Aerospace Engineering, Nuclear Engineering, or Thermal Sciences.

Demonstrated experience in heat exchanger design, analysis, manufacturing, and testing.

Experience with high-temperature (500°C+) systems, including thermal expansion, creep, fatigue, and material compatibility considerations.

Experience with thermal and structural finite element analysis (FEA) and computational fluid dynamics (CFD).

Experience designing high-temperature piping systems, manifolds, and associated mechanical components.

Experience evaluating piping flexibility, thermal stresses, and loads at equipment connections using analytical or simulation tools.

Familiarity with heat exchanger and piping fabrication methods, including welding, brazing, and other joining processes.

Experience designing pressure-containing components and familiarity with applicable ASME codes and standards (e.g., ASME BPVC Section VIII, ASME B31.1, or B31.3).

Experience developing and executing hardware validation tests, including pressure, thermal cycling, and performance testing.

Understanding of nuclear safety standards, quality requirements, and regulatory considerations.

Strong communication skills and ability to collaborate effectively across engineering, manufacturing, materials, quality, and testing teams.

Additional Requirements:

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

Location :

We are located in Torrance, CA in a 322,000 square foot, brand new facility featuring large open spaces for team collaboration, R&D, and production, as well as easy access

Salary Range:

Thermo-Mechanical Engineer II - $115,000 - $150,000

Culture

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 obsolete.” Over-optimizing the components often degrades the system

Obsess over the End User - The customer and end user are often not the same. We will never build globally competitive commercial products if we lose sight of our end users and their entire interaction with the product life cycle

Be Unconstrained by Convention - Our only limits are the laws of physics. Many, even experts, will say what we are working on is impossible. They said the same about SpaceX reusing rockets. Generationally impactful companies, by definition, must accomplish the seemingly impossible. If it were easy, it would have already been done. Never shy away from a solution because it has never been tried before, and never choose to do something because that's “how it's always been done”

Go Where the Work I s - Never miss a chance to meet a customer, user, or stakeholder face to face, even if that means hopping on a plane. If you can’t make it, find a teammate who can channel your intentions and go in your place. Deep work can be done from anywhere, but we believe teams are built in person, and aim to maximize our time together

Operate in the Grey - Embrace nuance in pursuit of truth. Question every fundamental assumption

Equal Opportunity

Antares is an Equal Opportunity Employer. Employment decisions are based solely on merit, competence, and qualifications, without regard to race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability, or any other legally protected status.

ITAR Requirements

To conform to U.S. Government export regulations, applicant must be a (i) U.S. citizen or national, (ii) U.S. lawful, permanent resident (aka green card holder), (iii) Refugee under 8 U.S.C. § 1157, or (iv) Asylee under 8 U.S.C. § 1158, or be eligible to obtain the required authorizations f