Senior Stress Engineer at Radiant in El Segundo, CA

Job description

About Radiant Radiant is an El Segundo, CA-based startup building the world’s first mass-produced, portable nuclear microreactors. Rising energy demand is straining the U.S. grid and driving up utility costs, emissions, and interconnection backlogs. Radiant decentralizes energy, producing power close to where it’s used. Its first reactor, Kaleidos, is a factory-built, 1-megawatt, fail-safe microreactor that can be transported by land, sea, or air and runs up to 5 years without refueling. Deployed locally without a decade-long build or permitting fight, Kaleidos provides independent power for critical infrastructure like military bases, data centers, hospitals, and remote sites. Founded in 2020, Radiant is under contract to deliver power to the U.S. Army, Air Force, Navy, and has pre-order agreements with Equinix, with deployments beginning in 2028. About the Role Radiant is seeking a Stress Engineer to own and execute structural loads, vibration, and dynamic analyses for complex mechanical systems associated for Kaleidos, the world's first portable microreactor and supporting hardware. You will play a critical role in ensuring structural integrity and survivability across all phases of the product lifecycle, including manufacturing, transportation, handling, deployment, and operational environments. This role requires a hands-on engineer who is comfortable working in ambiguous, fast-paced environments and collaborating closely with structures, mechanical design, thermal, nuclear, and test teams. Responsibilities & Duties: • Develop and own static, dynamic, and transient loads for reactor systems, support structures, and transport configurations. • Perform structural dynamics analyses, including modal, random vibration, shock, sine vibration, and fatigue assessments. • Implement explicit dynamics simulations to model nonlinear reactor response under transient seismic and transportation event cases. • Define and analyze transportation and handling environments, including shock and vibration from road, rail, air, or sea transport. • Generate load cases and environments to support structural sizing, design margins, and verification plans. • Conduct finite element analyses (FEA) using tools such as ANSYS, Abaqus, or similar tools. • Collaborate with design engineers to influence hardware architecture, material selection, and joint design. • Support test planning and correlation, including shaker tests, modal surveys, and structural verification testing. • Develop and maintain analysis documentation, reports, and requirements for internal reviews and regulatory interfaces. • Contribute to failure investigations, root cause analyses, and design improvements • Help establish best practices for loads, dynamics, and structural verification within a growing engineering organization. Required Qualifications & Skills: • Bachelor’s degree in Mechanical Engineering, Aerospace Engineering, Structural Engineering, or a related field. • 4+ years of professional experience in stress, loads, dynamics, or structural analysis for complex mechanical systems. • Strong fundamentals in structural mechanics, dynamics, and vibration. • Experience with finite element modeling and analysis of metallic and composite structures. • Proficiency with industry-standard FEA tools (e.g., ANSYS, Abaqus, Nastran). • Familiarity with design allowables, safety factors, and margin-of-safety methodologies. • Ability to work cross-functionally and communicate analysis results clearly to both technical and non-technical stakeholders. Desired Qualifications & Skills: • Experience in aerospace, launch, defense, nuclear, or heavy industrial hardware environments. • Dynamics modeling software experience (LD-Dyna, Abaqus explicit, or other). • Background in shock and vibration testing and test-article correlation. • Knowledge of fatigue, fracture mechanics, and bolted joint analysis. • Experience defining or interpreting environmental specifications and requirements. • Master’