Back to Jobs

Radiant

Mechanical Engineer, Fluid Systems

Location

El Segundo, CA

Wage

$107,500 – $150,000/yr

Employment Type

Full-time

Apply for This Position

Posted on September 11, 2026

Job Description

Overview

Radiant is an El Segundo, CA-based startup focused on developing portable nuclear microreactors. They are seeking a Mechanical Engineer for Fluid Systems to manage critical systems from design to production, contributing to the first new commercial reactor design in over 50 years.

Responsibilities

  • Own end-to-end engineering of fluid systems and components, including compressors, valves, and heat exchangers.
  • Perform complex thermal and fluids analysis to drive design decisions and verify system performance.
  • Conduct trade studies to optimize system and meet program requirements.
  • Develop and execute manufacturing/assembly instructions and test plans.
  • Create and manage a Bill-Of-Materials (BOM).
  • Find and develop suppliers for all components.
  • Own subassembly design, manufacturing, and test schedules.
  • Conduct risk analysis (FMEA) for subsystems.
  • Collect requirements and provide feedback to engineers in other functional areas.

Requirements

  • Bachelor’s degree in Mechanical, Materials, Aeronautical, Civil or Structural Engineering.
  • Experience with fluid system architecture design.
  • 2+ years of experience in designing, building, and testing fluids systems.
  • Proficient knowledge in fluid dynamics and thermodynamics.
  • Proficient knowledge of heat exchanger design and analysis methods.

Benefits

  • Health Insurance
  • Dental
  • Vision
  • PTO

Additional Information

  • Must be willing to work extended hours and weekends as necessary.
  • Must work 100% onsite at El Segundo HQ.

Benefits

Health Insurance
Dental
Vision
PTO
Apply for This Position

How this job compares in El Segundo, CA

Pay in context

At roughly $62/hr, this posting sits about 63% above the $38/hr median for welding jobs in El Segundo, CA — toward the top of a $38–$43/hr middle band drawn from 18 postings with published pay. Put another way, it pays more than about 89% of the comparable postings we have wage data for. Pay that far above local median usually comes attached to something: a harder cert requirement, travel, night shift, or overtime that isn't really optional. Worth establishing which before you accept.

The local market in El Segundo, CA

We're tracking 23 other active welding openings in El Segundo, CA right now, from 10 different employers. 17 of them were added in the last week. Across California as a whole we're tracking 623 other active welding openings from 288 employers. A metro this active generally means you have real leverage — employers here are competing for the same welders. Browse every welding job in El Segundo, or widen the search to California.

Radiant currently has 3 other openings live in California, which is usually a sign of either steady growth or steady turnover — worth asking which in the interview.

The most active employers in California at the moment, by number of open welding reqs, are SpaceX (34), Vast (22), and Relativity Space (20). Volume like that usually means either a genuine expansion or a staffing agency working several client sites — worth knowing which before you apply.

Within California, the best-paying metros we track by median hourly rate are Redondo Beach at $71/hr, Long Beach at $54/hr, and Torrance at $43/hr. If you can relocate or commute, that spread is worth factoring in.

Similar openings near El Segundo, CA

Pay figures are medians computed from live postings in the Welding Pros index, not from survey data, and they move as employers post. Mechanical Engineer, Fluid Systems figures were last recalculated when this page was built.