Senior Mechanical Engineer, Structures

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 highly motivated Senior Mechanical Engineer to design and develop critical structures within Kaleidos.

You will solve unique challenges creating efficient and reliable structures that facilitate fission while surviving extreme temperature environments and meeting volumetric constraints. You will be responsible for the following: trade studies, material selection, detailed structural analysis, assembly, integration, and testing. You will have an instrumental impact of fueling the first new commercial reactor design in over 50 years by 2026.  

Responsibilities & Duties:
Ownership of critical structures such as mass-efficient transportable shielding systems, container system, and high temperature graphite and metallic systems.

Conduct trade studies and develop designs to meet program requirements. Perform detailed thermomechanical analysis (static strength, durability/fatigue) and dynamic analysis (vibration, shock) to determine structural integrity (margins of safety) using both hand calculations and finite element tools.

Develop and execute manufacturing/assembly instructions and test plans.

Create and manage a Bill-Of-Materials (BOM).Find and develop suppliers for components.

Own subassembly design, manufacturing, and test schedules.

Own risk analysis (FMEA) for subsystems.

Collect requirements, provide expertise and feedback to engineers in other functional areas via clear, constructive communication.

Required

Qualifications & Skills:

Bachelor’s degree from an accredited institution in Mechanical, Aeronautical, Civil or Structural Engineering.
6+ years of experience designing structures.
4+ years of experience performing stress analysis using both hand calculations and finite element tools (Abaqus, Ansys, FEMAP, or similar).Desired

Qualifications & Skills:

Experience with design of multi-component assemblies in CAD (NX or similar).Experience designing hardware that was manufactured, deployed, and iteratively improved.

Experience resolving thermal expansion issues in designs.

Experience working with interdisciplinary teams.

Solid understanding and application of GD&T.Proficiency with both “hand calc” analytical methods and higher fidelity finite element-based analysis methods.

Ability to derive free-body diagrams for systems with which one was not previously familiar.

Self-motivated with strong organizational, written, and oral communication skills.

Experience with using text-based software development tools.

Additional Requirements:

Must be willing to work extended hours and weekends as necessary to accomplish our mission.

Must work 100% onsite at El Segundo HQ.Benefits and Perks Stock:
Substantial incentive stock plan for all full-time employees.

Medical: 100% up to base silver level plan for employee + 50% dependents, offers up to Platinum plans.

One Medical:
Sponsored memberships for employees and their dependents.

Vision:…