Mechanical Engineer, Electrical Systems

Radiant•El Segundo, CA

2d•Onsite

About The Position

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 failsafe microreactor that can be transported anywhere power is needed and run for up to five years without the need to refuel. 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 utilizes modern software engineering to rapidly achieve safe, factory-built microreactors that leverage existing, well-qualified materials. Founded in 2020, Radiant is on track to test its first reactor next year at the Idaho National Laboratory, with initial customer deliveries beginning in 2028. Radiant is seeking a highly motivated early-career Mechanical Engineer to support the design and integration of electrical components and subsystems in a fast-paced startup environment. You’ll work alongside experienced mechanical and electrical engineers to solve challenging problems in packaging, thermal management, structural design, and system integration for advanced hardware. This role offers hands-on exposure to end-to-end hardware development—from CAD and analysis through build, test, and validation—while contributing directly to Radiant’s mission to deploy the first successfully fueled commercial reactor in over 50 years by 2026.

Requirements

Bachelor’s degree in Mechanical Engineering or a closely related field from an accredited institution
Hands-on experience with mechanical design through coursework, labs, internships, senior design projects, or engineering clubs
Proficiency or coursework experience using Siemens NX or similar 3D CAD tools
Familiarity with mechanical design of electrical assemblies, including enclosures, brackets, and harness routing principles
Basic understanding of structural mechanics, load paths, and first-order stress calculations
Introductory knowledge of thermal analysis, heat transfer, and thermal management concepts
Ability to read and create mechanical drawings, including dimensions and tolerances
Strong communication skills and ability to collaborate in a multidisciplinary engineering environment
Must be willing to work extended hours and weekends as necessary to accomplish our mission
Must work 100% onsite at El Segundo HQ
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.

Responsibilities

Support the mechanical design and ownership of electrical components and subsystems, including:
Mechanical design of electrical assemblies such as control panels, enclosures, brackets, mounts, and supports
Cable and wiring harness routing, retention, strain relief, bend radius compliance, and serviceability considerations
Packaging of sensors, actuators, connectors, and electrical hardware within constrained assemblies
3D CAD modeling and 2D drawing creation using Siemens NX, including tolerance stack-ups and GD&T basics
Perform first-order load calculations (static, shock, vibration) to support structural design decisions
Conduct thermal analysis and heat-transfer assessments for electrical components, enclosures, and assemblies
Support selection of materials, fasteners, and finishes appropriate for electrical, thermal, and environmental requirements
Assist in the design and setup of test fixtures and test stands for acceptance and qualification testing
Participate in system integration, troubleshooting, and validation activities alongside electrical and systems engineers
Collect and interpret technical requirements and provide clear, constructive feedback across mechanical, electrical, software, and systems disciplines
Develop, document, and execute basic test plans and procedures to verify mechanical and thermal performance
Perform trade studies and first-order analyses to evaluate design options and constraints
Generate and maintain design documentation to support Design for Manufacturing (DFM), assembly, and serviceability
Support subassembly design, coordinate with manufacturing, and assist with build and test schedules

Benefits

Stock: Substantial incentive stock plan for all full-time employees.
Medical: 100% premium coverage for base Silver level plan for employee + 50% premium coverage for dependents. Platinum plans available.
One Medical: Sponsored memberships for eligible employees and their dependents.
Vision: 100% premium coverage for top tier plan + 50% for dependents.
Dental: 100% premium coverage for top tier plan (including orthodontia) + 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.