Prinicpal Engineer, Structural Integrity

Antares; Los Angeles, Northern (CA, KY); On-site; USD 150,000 - 230,000; Full time

Job summary

Antares seeks a Principal Engineer, Structural Integrity to build and own our methods for high‑temperature reactor components (including heat pipes). You will connect material behavior, testing, modeling, code requirements, and actual component integrity to establish a long‑term technical foundation for Antares.

The role interfaces with Materials, Mechanical Design, Safety Analysis, Licensing, Quality, and Operations, focusing on metallic materials with valuable graphite experience.

Qualifications

• Deep expertise in structural integrity, materials modeling, or high-temperature component design.
• Ability to establish technical methods and frameworks used across an organization.
• Strong understanding of metallic behavior under temperature, time, irradiation, and cyclic loading.
• Experience with creep, fatigue, creep-fatigue, fracture, crack growth, and nonlinear structural analysis.
• Significant experience with ASME Section III, Division 5; exposure to Sec 11 is a plus.
• Experience turning material testing output into models, design curves, or acceptance criteria.
• Strong finite-element and constitutive modeling background.
• Knowledge of verification, validation, uncertainty, and qualification of engineering methods.
• Ability to defend engineering judgments with incomplete data and drive closure.
• Cross-functional collaboration across materials testing, modeling, design, safety, and operations.
• Advanced reactor or high-temperature nuclear experience.

Responsibilities

• Build and own the structural integrity framework covering design, qualification, operation, aging, and fitness for service.
• Serve as the technical authority for structural integrity and materials modeling across Antares.
• Lead application of ASME Section III, Division 5 for high-temperature components.
• Incorporate R5/R6 methods for high-temperature life assessment, fracture, and remaining life.
• Translate material test data into qualified models, design properties, and acceptability criteria.
• Develop and qualify methods for creep, fatigue, creep-fatigue, ratcheting, thermal aging, irradiation effects, fracture, and crack growth.
• Define material testing and irradiation data needs to support current designs and long-term qualification.
• Link material behavior/results to design margins, inspection requirements, and life expectancy.
• Establish methods for evaluating manufacturing defects, degradation, and fitness for continued service.
• Support aging management, surveillance, remaining-life assessment, and asset-management strategies.
• Own the technical basis, verification, validation, uncertainty, and qualification approach for modeling methods.
• Mentor engineers across materials and structural analysis and help set long-term direction.

Skills

Structural integrity

Materials modeling

High-temperature design

Creep

Fatigue

Fracture mechanics

Finite element analysis

ASME III Div 5

Validation & uncertainty

Cross-functional leadership

Education

Advanced engineering degree

Job description

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 Principal Engineer, Structural Integrity you will build and own our structural integrity methods and tools for high-temperature reactor components (including heat pipes). This individual will connect material behavior, testing, modeling, code requirements, and actual component integrity, and establish that capability as a long-term technical foundation for Antares. This role will be part of larger Nuclear Methods and work closely with Materials, Mechanical Design and Analysis, Safety Analysis, Licensing, Quality, and Operations.

The focus is primarily metallic materials, but graphite experience is highly valuable.

Roles and Responsibilities:

• Build and own the Antares structural integrity framework covering design, qualification, operation, inspection, aging, and fitness for service.

• Serve as the technical authority for structural integrity and materials modeling across Antares.

• Lead application of equivalency applicable ASME Section III, Division 5 for high-temperature components.

• Bring relevant R5 and R6 methods into the Antares framework for high-temperature life assessment, fracture, defect tolerance, and remaining life.

• Translate material test data into qualified material models, design properties, allowables, and acceptance criteria used in structural analysis.

• Develop and qualify methods for creep, fatigue, creep-fatigue, ratcheting, thermal aging, irradiation effects, fracture, and crack growth.

• Define the material testing and irradiation data needed to support current design decisions and longer-term qualification.

• Connect material behavior and test results directly to design margins, inspection requirements, and allowable operating life.

• Establish methods for evaluating manufacturing defects, inspection findings, degradation, and fitness for continued service.

• Support aging management, surveillance, remaining-life assessment, and asset-management strategies.

• Own the technical basis, verification, validation, uncertainty, and qualification approach for structural and materials modeling methods.

• Guide and mentor engineers across materials and structural analysis and help set the long-term technical direction for the capability.

Basic Qualifications

• Principal or Distinguished-level engineer with deep expertise in structural integrity, materials modeling, or high-temperature component design.

• Demonstrated ability to establish technical methods and frameworks used across an organization.

• Strong understanding of metallic behavior under temperature, time, irradiation, and cyclic loading.

• Deep experience with creep, fatigue, creep-fatigue, fracture, crack growth, and nonlinear structural analysis.

• Significant experience with ASME Section III, preferably Division 5. Additionally, exposure to Sec 11 rules/practices

• Experience taking material testing output and turning it into models, design curves, allowables, or engineering acceptance criteria.

• Strong finite-element and constitutive modeling background.

• Strong understanding of verification, validation, uncertainty, and qualification of engineering methods.

• Ability to make and defend engineering judgments where data are incomplete and establish a credible path to closure.

• Ability to work across materials testing, modeling, design, safety, licensing, quality, and operations.

• Advanced reactor or other high-temperature nuclear experience.

Preferred Skills & Experience

• Direct experience with UK R5 and R6 methods.

• Experience with irradiation effects on metallic materials.

• Experience with fitness for service, defect tolerance, aging management, or asset management.

• Experience developing ASME Code Cases or alternative structural integrity methodologies.

• Knowledge of nuclear graphite and ASME Section III, Division 5 graphite rules.

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 from the U.S. Department of State. Learn more about the ITAR here.