Demo

Senior Mechanical Engineer, Fluid Systems

Radiant
El Segundo, CA Full Time
POSTED ON 4/25/2026
AVAILABLE BEFORE 6/17/2026
Senior Mechanical Engineer , Fluids Systems

Radiant is seeking a highly motivated Senior Mechanical Engineer, Fluids Systems to own critical Kaleidos fluid systems from preliminary design through build and production. These systems include the primary loop subsystems and power conversion loop, serving to convert heat from the reactor core into electrical power. You will be responsible for the following: trade studies, component selection, thermal hydraulic analysis, piping design, vendor selection, assembly, and testing. You will have an instrumental impact of fueling the first new commercial reactor design in over 50 years by 2026.  

Responsibilities & Duties

  • 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, verify system performance, and ensure structural integrity using first-principle hand calculations and finite element tools. 
  • Perform 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. 
  • 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, Materials, Aeronautical, Civil or Structural Engineering.  
  • Experience with fluid system architecture design. 
  • 4 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. 

Desired Qualifications & Skills  

  • Knowledge of thermodynamic power cycles. 
  • Prior experience with designing piping system for thermal growth using hand calculations and FEA tools. 
  • Experience with process piping design and testing codes, such as ASME B31.3 and ASME PCC-2. 
  • Prior experience with fluid system modeling via Matlab/Python.  
  • Experienced in design for manufacturability and ramping up hardware build in a production environment. 
  • Experienced in designing and operating test stands.  
  • Takes extreme ownership of work and a high degree of responsibility.  
  • Excellent communication across multidisciplinary teams.  
  • Prior nuclear experience in not required for this role. 

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. If that’s you, contact us directly for immediate opportunities: recruiting@radiantnuclear.com.

We are an equal opportunity employer and all qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity or expression, pregnancy, age, national origin, disability status, genetic information, protected veteran status, or any other characteristic protected by law.

Unfortunately, we are unable to provide visa sponsorship at this time.

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.

Compensation Range: $139.5K - $224.7K

Salary : $139,500 - $224,700

If your compensation planning software is too rigid to deploy winning incentive strategies, it’s time to find an adaptable solution. Compensation Planning
Enhance your organization's compensation strategy with salary data sets that HR and team managers can use to pay your staff right. Surveys & Data Sets

What is the career path for a Senior Mechanical Engineer, Fluid Systems?

Sign up to receive alerts about other jobs on the Senior Mechanical Engineer, Fluid Systems career path by checking the boxes next to the positions that interest you.
Income Estimation: 
$108,186 - $133,193
Income Estimation: 
$134,236 - $174,128
Income Estimation: 
$132,162 - $161,329
Income Estimation: 
$108,186 - $133,193
Income Estimation: 
$134,236 - $174,128
Income Estimation: 
$132,162 - $161,329
Employees: Get a Salary Increase
View Core, Job Family, and Industry Job Skills and Competency Data for more than 15,000 Job Titles Skills Library

Job openings at Radiant

  • Radiant El Segundo, CA
  • Senior Automation & Controls Engineer Radiant is seeking a highly motivated senior automation and controls engineer who will be working close with design a... more
  • 1 Day Ago

  • Radiant El Segundo, CA
  • Radiant is seeking a talented Senior Electrical Engineer to own designs from requirements capture through operation. The candidate will be directly respons... more
  • 1 Day Ago

  • Radiant El Segundo, CA
  • Radiant is an El Segundo, CA-based startup building the world's first mass-produced, portable nuclear microreactors. The company's first reactor, Kaleidos,... more
  • 1 Day Ago

  • Radiant El Segundo, CA
  • Responsibilities And Duties Read engineering drawings, electrical schematics, and wiring diagrams. Assemble, wire, and integrate hardware including PCBs, h... more
  • 1 Day Ago


Not the job you're looking for? Here are some other Senior Mechanical Engineer, Fluid Systems jobs in the El Segundo, CA area that may be a better fit.

  • Radiant El Segundo, CA
  • Mechanical Engineer , Fluids Systems Radiant is seeking a highly motivated Mechanical Engineer, Fluids Systems to own critical Kaleidos fluid systems from ... more
  • 14 Days Ago

  • Radiant El Segundo, CA
  • Radiant is seeking a highly motivated Mechanical Engineer, Fluid Systems - 2026 New Graduate to join the KDU Engineering team. You will contribute directly... more
  • 23 Days Ago

AI Assistant is available now!

Feel free to start your new journey!