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Reactor Engineer Jobs in California (NOW HIRING)

Radiant

Senior Nuclear Thermal-Hydraulics Engineer

El Segundo, CA · On-site

$111K - $152K/yr

  • Medical

  • Dental

  • Vision

  • Life

  • PTO

The company's first reactor, Kaleidos, is a 1-megawatt, fail-safe microreactor that can be ... This role is suited to engineers with reactor-specific thermal-hydraulics or coupled multiphysics ...

Reactor

Senior Product Designer

San Francisco, CA · On-site

  • Medical

  • Dental

  • Vision

Engineering Employment Type: Full Time Location: San Francisco Description Real-time video AI and ... You'll own design at Reactor end-to-end. That means defining the problem, exploring solutions ...

Oklo

Software Engineer

Santa Clara, CA · On-site +1

$110K - $155K/yr

  • Medical

  • Retirement

Build tools for reactor engineers to visualize, compare, and evaluate reactor designs and their physics * Integrate simulation tools into our analyses pipelines * Implement physics kernels to solve ...

Oklo

Software Engineer

Santa Clara, CA · On-site +1

$110K - $155K/yr

  • Medical

  • Retirement

Build tools for reactor engineers to visualize, compare, and evaluate reactor designs and their physics * Integrate simulation tools into our analyses pipelines * Implement physics kernels to solve ...

Radiant

Reactor Operations Training Specialist

El Segundo, CA · On-site

$150K - $207K/yr

  • Medical

  • Dental

  • Vision

  • Life

  • PTO

This role may also support engineering operations through the development of test plans, data ... Translate evolving reactor designs and operational concepts into clear, concise, and easily ...

Oklo

Senior Software Engineer

Santa Clara, CA · On-site +1

$160K - $200K/yr

  • Medical

  • Retirement

Develop reactor optimization schemes and statistical experiments to inform design changes * Mentor other engineers, set technical direction, and contribute to building a strong engineering culture ...

Oklo

Senior Software Engineer

Santa Clara, CA · On-site +1

$160K - $200K/yr

  • Medical

  • Retirement

Develop reactor optimization schemes and statistical experiments to inform design changes * Mentor other engineers, set technical direction, and contribute to building a strong engineering culture ...

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Showing results 21-40

All JobsReactor Engineer JobsReactor Engineer Jobs in California

Reactor Engineer information

See California salary details

$58.7K

$110.2K

$200.3K

How much do reactor engineer jobs pay per year?

As of Aug 16, 2026, the average yearly pay for reactor engineer in California is $110,170.00, according to ZipRecruiter salary data. Most workers in this role earn between $79,400.00 and $130,800.00 per year, depending on experience, location, and employer.

What is a reactor engineer?

Reactor Engineers are professionals who design, operate, and maintain nuclear reactors. They are responsible for ensuring the safe and efficient functioning of reactors used for power generation, research, or medical purposes. Their work involves monitoring reactor systems, conducting safety assessments, and developing procedures to prevent accidents. Reactor Engineers also analyze reactor performance data and collaborate with other engineers and scientists to optimize reactor operations.

What are some common challenges faced by reactor engineers during routine operations and how are they addressed?

Reactor Engineers often encounter challenges such as maintaining reactor stability, troubleshooting instrumentation issues, and ensuring compliance with strict safety protocols. These challenges are typically managed through continuous monitoring, collaboration with multidisciplinary teams (including safety, operations, and maintenance personnel), and adherence to established procedures. Proactive communication and regular training enable Reactor Engineers to respond effectively to unexpected events and maintain optimal reactor performance.

What are the key skills and qualifications needed to thrive as a reactor engineer, and why are they important?

To thrive as a Reactor Engineer, you need a solid background in nuclear engineering, reactor physics, and safety protocols, typically supported by a degree in nuclear engineering or a related field. Familiarity with simulation software, reactor monitoring systems, and safety certification such as Fundamentals of Engineering (FE) or Professional Engineering (PE) is often required. Strong analytical thinking, attention to detail, and effective communication skills help you solve complex technical problems and work within multidisciplinary teams. These skills ensure the safe, efficient, and regulatory-compliant operation of nuclear reactors, which is critical for both safety and energy production.

What is the difference between Reactor Engineer vs Nuclear Engineer?

AspectReactor EngineerNuclear Engineer
CredentialsBachelor's in Nuclear Engineering or related field; often requires licensing or certificationBachelor's or higher in Nuclear Engineering; may also require licensing
Work EnvironmentDesign, operate, and maintain nuclear reactors, often in power plants or research facilitiesResearch, develop, and improve nuclear systems, including reactors and radiation safety
Industry UsagePrimarily in power generation, naval propulsion, and research reactorsResearch institutions, government agencies, and industry R&D

Reactor Engineers focus on the operation and safety of nuclear reactors, ensuring they run efficiently and safely. Nuclear Engineers have a broader scope, including research, development, and design of nuclear systems. Both roles require similar educational backgrounds and certifications, but Reactor Engineers are more hands-on with reactor operation, while Nuclear Engineers often work on innovation and system improvements.

What are popular job titles related to Reactor Engineer jobs in California?

For Reactor Engineer jobs in California, the most frequently searched job titles are:

What job categories do people searching Reactor Engineer jobs in California look for?

The top searched job categories for Reactor Engineer jobs in California are:

What cities in California are hiring for Reactor Engineer jobs?

Cities in California with the most Reactor Engineer job openings:

Reactor Engineer jobs near you
Infographic showing various Reactor Engineer job openings in California as of August 2026, with employment types broken down into 88% Full Time, 5% Part Time, 2% Temporary, and 5% Contract. Highlights an 86% Physical, 5% Hybrid, and 9% Remote job distribution, with an average salary of $110,170 per year, or $53 per hour.

Senior Nuclear Thermal-Hydraulics Engineer

Radiant

El Segundo, CA • On-site

$139K - $196K/yr

Full-time

Medical, Dental, Vision, Life, PTO

Posted 22 days ago

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 Senior Nuclear Thermal-Hydraulics Engineer to lead thermal-hydraulics and coupled physics analysis for the Kaleidos microreactor. You will own the modeling that determines how heat, coolant, and reactor core behavior interact under normal and accident conditions - work that directly informs core design, cooling systems, and safety case development for the first mass-produced nuclear reactor. This role is suited to engineers with reactor-specific thermal-hydraulics or coupled multiphysics experience who want to apply that depth to a fast-moving, factory-built reactor program.
Responsibilities & Duties
  • Own and execute thermal-hydraulics analysis to evaluate design and safety performance of Kaleidos reactor systems under normal and accident conditions.
  • Develop and apply coupled physics models integrating thermal-hydraulics with neutronics and/or structural response.
  • Identify and implement best practices for reactor thermal-hydraulics and systems-code analysis.
  • Build automated workflows to expand simulation capabilities, accuracy, and efficiency.
  • Collaborate across reactor physics, mechanical, and safety teams to support licensing and design trade studies.

Required Qualifications & Skills
  • Bachelor's degree in nuclear engineering, mechanical engineering, physics, or similar field from an accredited institution.
  • 5+ years of relevant industry or national laboratory experience.
  • Experience with thermal-hydraulics analysis and/or reactor systems codes (e.g., RELAP5, TRACE, CTF/COBRA-TF, SAM, TRANSFORM).
  • Experience with high-temperature (500°F+) heat transfer analysis involving conduction, convection, and radiation.
  • Experience communicating and distilling technical information with cross-functional teams.

Desired Qualifications & Skills
  • Experience with coupled multiphysics modeling (e.g., MOOSE, BISON, MARMOT) or neutronics coupling.
  • Experience with commercial CFD/FEA tools (STAR-CCM+, Ansys Fluent) and CAD (Siemens NX).
  • Prior experience at a national laboratory, reactor vendor, or advanced reactor developer.
  • Driven, self-motivated, and takes ownership of work end to end.

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.
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.

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