Senior Mechanical Engineer, Mechanisms

Radiant; El Segundo, Northern (CA, KY); Hybrid; USD 120,000 - 190,000; Full time

Benefits offered by this job

Stock: equity plan

Medical benefits

One Medical: memberships

Vision and Dental coverage

Parental leave

Paid lunches

Flexible PTO

Job summary

Radiant, an El Segundo, CA-based startup building portable nuclear microreactors, seeks a Senior Mechanical Engineer, Mechanisms, to design and develop critical mechanisms within Kaleidos. You will perform trade studies, material selection, and detailed structural analysis to ensure reliability and safety.

This on-site role involves ownership of actuators/valves, BOM management, supplier development, and cross-functional collaboration to meet program goals and deliverables as the company scales.

Qualifications

• Bachelor’s degree in Mechanical or Aeronautical Engineering.
• 4+ years designing mechanisms.
• 4+ years of stress analysis with hand calculations and FE tools.

Responsibilities

• Own critical mechanisms like actuators and valves.
• Perform trade studies and develop designs to meet requirements.
• Conduct thermomechanical and kinematic analyses to ensure structural integrity.
• Develop manufacturing/assembly instructions and test plans.
• Create and manage a BOM and coordinate supplier development.
• Lead subassembly design, manufacturing, and test schedules.
• Perform risk analysis (FMEA) for subsystems.
• Collaborate with cross-functional teams and communicate requirements.

Skills

Mechanism design

Finite element analysis

Engineering degree

Education

Bachelor in Mechanical/Aeronautical Eng

Tools

NX CAD

Abaqus/Ansys/FEMAP

Job description

About Radiant

Radiant is an El Segundo, CA-based startup building the world’s first mass-produced, portable nuclear microreactors. The company’s first reactor, Kaleidos, is a 1-megawatt, fail-safe microreactor that can be transported anywhere power is needed and run for up to 5 years without refueling. Portable nuclear power with rapid-deploy capability can replace similar-sized diesel generators and provide critical asset support for hospitals, data centers, remote sites, and military bases. Radiant’s unique, practical approach to nuclear development leverages modern software engineering to rapidly deliver safe, factory-built microreactors that use existing, well-qualified materials. Founded in 2020, Radiant is on track to test its first reactor at the Idaho National Laboratory this summer, with initial customer deliveries beginning in 2028.

About the Role

Radiant is seeking a highly motivated Senior Mechanical Engineer, Mechanisms to design and develop critical mechanisms within Kaleidos. You will solve unique challenges creating efficient and reliable mechanisms that control reactivity or actuate critical safety features. 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 mechanisms such as the control blade actuator or air jacket valves.

• Conduct trade studies and develop designs to meet program requirements.

• Perform detailed thermomechanical analysis (static strength, durability/fatigue) and kinematic analysis to determine structural integrity and performance margins 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 or Aeronautical Engineering.

• 4+ years of experience designing mechanisms.

• 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 designing pneumatic systems.

• Experience integrating electromechanical components such as motors or encoders.

• 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: 100% top tier plan coverage + 50% for dependents.

• Dental: 100% top tier plan coverage, orthodontia extra, 50% for dependents.

• Voluntary life, accident, hospital, critical illness, commuter and FSA/HSA are offered as employee contributed benefits.

• 8-weeks of paid parental leave for all parents. Additional paid pregnancy leave for CA 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.

• Beautiful El Segundo headquarters close to the Pacific Ocean.

Total Compensation and Benefits
Radiant compensates people for impact and invests in those who continue to raise the bar. Radiant’s new hire compensation package includes base salary, substantial equity grants, and comprehensive health benefits. Total compensation and level are determined through a rigorous evaluation of interview performance, experience, education, and qualifications, and are designed to support continued growth as scope, responsibility, and impact expand at Radiant.
The best of today’s advanced reactor builders don’t wait for job postings. They join the winning team.

This position involves access to technology that is subject to U.S. export controls. Any job offer made will be contingent upon the applicant’s capacity to serve in compliance with U.S. export controls.