Senior Nuclear Methods Engineer

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 Senior Nuclear Methods Engineer you are responsible for developing, qualifying, and continuously improving the nuclear analysis methods that underpin reactor design, safety, and licensing. The position owns the technical foundation for steady-state and transient analyses, ensures engineering rigor through validation and uncertainty management, and translates nuclear methods into actionable design inputs for hardware development, manufacturing, and reactor operation. A key aspect of the role is continuously improving design confidence and recovering margin by incorporating lessons learned from testing and operational data throughout the reactor lifecycle. Key Responsibilities - Develop and maintain steady-state and transient nuclear analysis methods used for reactor design, safety analysis, and licensing. - Qualify analysis methods through code-to-code comparisons, benchmark problems, experimental validation, and uncertainty quantification. - Establish, document, and maintain biases, uncertainties, conservatisms, and design margins across all nuclear analysis methods. - Perform gap analyses to identify deficiencies in methods, validation data, tools, and technical capabilities, and develop plans to close those gaps. - Ensure nuclear analysis products are directly mapped to the needs of the safety case, licensing basis, mechanical design, manufacturing, and hardware delivery. - Develop sensitivity and uncertainty capabilities to quantify the impact of design changes, manufacturing tolerances, and operational variability on reactor performance and safety margins. - Define best practices and analysis workflows that maintain traceability, consistency, and engineering rigor throughout the design lifecycle. - Work closely with design, safety, licensing, materials, manufacturing, and testing teams to ensure analysis methods support program milestones and engineering decisions. - Leverage data from component testing, integrated system testing, and reactor operation to continuously improve methods, reduce uncertainty, and recover design margin for future block upgrades. Basic Qualifications - Bachelor’s degree in Nuclear Engineering, Mechanical Engineering, Physics, or a related technical discipline. - 4+ years of professional experience in nuclear engineering, reactor physics, nuclear methods development, safety analysis, or a related field. - Experience with reactor physics and transport tools such as MCNP, Serpent, SCALE, OpenMC, MOOSE-based applications, or similar codes. - Experience with transient reactor analysis and coupled neutronics/thermal-hydraulics methods. - Experience performing steady-state and/or transient analysis of nuclear reactor systems. - Working knowledge of reactor physics, neutronics, thermal-hydraulics, or coupled Multiphysics analysis. - Experience using nuclear analysis or simulation tools to support reactor design, safety analysis, or engineering decisions. - Understanding of verification and validation (V&V), benchmarking, sensitivity analysis, and/or uncertainty quantification. - Ability to translate analytical results into engineering requirements, design inputs, margins, and technical recommendations. - Strong technical documentation skills with the ability to clearly communicate assumptions, methodologies, uncertainties, and results to multidisciplinary engineering teams. Preferred Skills & Experience - Master’s or Ph.D. in Nuclear Engineering, Reactor Physics, Applied Physics, or a related technical discipline. - Experience developing, qualifying, or maintaining nuclear analysis methods rather than solely applying established tools. - Demonstrated experience with code-to-code comparisons, benchmark evaluations, experimental validation, sensitivity analysis, and uncertainty quantification. - Experience establishing and managing analytical biases, uncertainties, conservatisms, and design margins. - Familiarity with nuclear regulatory and licensing frameworks and the development of analysis methods used to support a safety case or licensing basis. - Experience developing automated analysis workflows, data pipelines, or engineering tools using Python, C++, MATLAB, or similar programming languages. - Experience incorporating test or operational data into model calibration, validation, uncertainty reduction, or design-margin recovery. - Experience supporting advanced reactor development, including microreactors, high-temperature gas reactors, fast reactors, molten salt reactors, or other non-light-water reactor technologies. - Familiarity with software quality assurance, configuration management, and traceability requirements for safety-related or licensing analysis tools. 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 Is - 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 https://www.pmddtc.state.gov/?id=ddtc_kb_article_page&sys_id=24d528fddbfc930044f9ff621f961987.