Principal Thermal Modeling Engineer

Radiant Industries•El Segundo, CA

2d•Onsite

About The Position

Radiant is seeking a Principal Thermal Modeling Engineer to set the technical direction for computational fluid dynamics (CFD) and thermal finite element analysis (FEA) for its Kaleidos microreactor. The role leads complex, high-consequence modeling for a high-temperature gas reactor and defines modeling methods, standards, and validation strategies that inform reactor systems, cooling systems, shielding, and other design areas. The engineer will serve as a technical authority, mentor engineers, influence program-level decisions, and support milestones toward commercialization of the reactor. The position collaborates with design, systems, and test teams to develop analysis methods and translate results into recommendations for engineering leadership. It also leads model verification and validation, automated simulation workflows, reduced-order methods, and cross-disciplinary technical decision-making. The role is based 100% onsite at Radiant’s El Segundo, California headquarters. Extended hours and weekends may be necessary. The position involves access to technology subject to U.S. export controls; any offer is contingent on the applicant’s ability to serve in compliance with those controls.

Requirements

Bachelor’s degree in engineering, physics, or a similar field from an accredited institution.
10+ years of relevant industry experience, with a track record of technical leadership on complex, high-consequence programs.
Extensive experience with STAR-CCM+, Ansys Fluent, or other commercial CFD codes, including advanced turbulence and conjugate heat transfer modeling.
Mastery of finite element and computational fluid dynamics principles and methods, with demonstrated experience validating models against test data.
Proficiency with CAD software, specifically Siemens NX.
Experience building automated simulation workflows and scripting tools.
Demonstrated ability to mentor engineers and communicate complex technical results to cross-functional teams and leadership.
Willingness to work extended hours and weekends as necessary.
Ability to work 100% onsite at the El Segundo headquarters.
Capacity to serve in compliance with U.S. export controls.

Nice To Haves

Advanced degree (MS or PhD).
Experience with radiation heat transport modeling.
Knowledge of nuclear reactor design, thermal-hydraulics, or safety analysis.
Experience with multiphysics coupling, such as thermal-structural or neutronics-thermal.
Experience with reduced-order modeling or system-level thermal-hydraulic codes.
Experience with regulatory or safety-basis analysis.
A self-motivated approach and ownership of work end to end.
Experience in the aerospace or automotive industry.

Responsibilities

Serve as the technical authority for thermal CFD and thermal FEA modeling of Kaleidos reactor systems, owning the most complex and highest-risk analyses.
Define modeling strategy, methodology, and best practices for turbulent flow, heat transfer, and multiphysics interactions, and drive their adoption across the team.
Lead model verification and validation by correlating simulation results with test data and establishing confidence and uncertainty bounds for design and safety decisions.
Architect automated simulation workflows and tooling to expand capability, accuracy, and efficiency, and set the roadmap for simulation infrastructure.
Lead development of reduced-order analysis methods in partnership with design, systems, and test teams.
Influence reactor, cooling, and shielding design decisions by translating analysis results into clear recommendations for engineering leadership.
Mentor and develop engineers, set the technical bar through design and analysis reviews, and contribute to hiring.
Collaborate across disciplines to define analysis requirements, align priorities, and resolve cross-team technical tradeoffs.

Benefits

Substantial incentive stock plan for all full-time employees.
Medical coverage up to the base silver level plan at 100% for the employee and 50% for dependents, with plans up to Platinum available.
Sponsored One Medical memberships for employees and their dependents.
Vision coverage at 100% for the top-tier plan and 50% for dependents.
Dental coverage at 100% for the top-tier plan, with orthodontia extra, and 50% coverage for dependents.
Voluntary life, accident, hospital, and critical illness coverage, plus commuter benefits and FSA/HSA, offered as employee-contributed benefits.
Eight weeks of paid parental leave for all parents.
Additional paid pregnancy leave for California employees.
Nuclear Engineering Certificate Program with tuition fully covered through Penn State University for eligible employees.
Daily catered lunch.
Free snacks and drinks.
Flexible PTO policy.
Remote workday allocation.
Company and team-bonding events, happy hours, and in-person camaraderie.
El Segundo headquarters close to the Pacific Ocean.