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Radiant

Test Engineer, Mechanical/Fluids

Location

El Segundo, CA

Wage

$106,500 – $146,475/yr

Employment Type

Full-time

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Posted on November 11, 2026

Job Description

Overview

Radiant is an El Segundo, CA-based company building the world's only mass-produced, transportable nuclear microreactors. They are seeking a Test Engineer to drive test operations for the development, qualification, and acceptance of their nuclear microreactor technology, focusing on fluid and mechanical systems.

Responsibilities

  • Perform testing as a Test Conductor/Test Director to ensure procedures align with real-world execution.
  • Partner with design engineers to develop innovative test methods for complex mechanisms and structures.
  • Support testing and iterative improvements of fluid, electrical, and structural hardware of the Kaleidos reactor.
  • Identify and develop appropriate suppliers for component sourcing and fabrication.
  • Drive initiatives for continuous improvement in test processes and data delivery quality.
  • Support one-off test campaigns to drive hardware risk reduction.
  • Ensure compliance with DOE and NRC standards in procedural documentation.

Requirements

  • 2+ years of full-time professional experience in engineering problem-solving, including system design, analysis, or testing.
  • Bachelor’s degree from an accredited institution in mechanical, manufacturing, or other related engineering discipline.
  • Ability to apply first principles thinking to solve problems and make decisions in uncertain situations.
  • Background in highly regulated industries (e.g., nuclear, aerospace, aviation, maritime).
  • Demonstrated ability to lead projects and work independently.
  • Strong technical fundamentals in fluids and thermodynamics.
  • Strong written and verbal communication skills.
  • Flexible and adaptable mindset - self-driven with minimal direction.

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 $61/hr, this posting sits about 15% above the $53/hr median for welding jobs in El Segundo, CA — toward the top of a $48–$72/hr middle band drawn from 12 postings with published pay. Put another way, it pays more than about 67% 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 13 other active welding openings in El Segundo, CA right now, from 12 different employers. 7 of them were added in the last week. Across California as a whole we're tracking 505 other active welding openings from 240 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 1 other opening 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 (37), Relativity Space (18), and Welding Shop in Los Angeles, CA (13). 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 El Segundo at $53/hr, Los Angeles at $51/hr, and Pasadena at $50/hr. El Segundo is among them.

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. Test Engineer, Mechanical/Fluids figures were last recalculated when this page was built.