<div>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.</div>Nuclear EngineerRadiant is seeking a highly motivated nuclear engineer responsible for developing nuclear engineering solutions for our Kaleidos microreactor. This may include nuclear engineering areas such as radiation shielding, criticality safety, accident dose consequence, reactor physics modeling and design, transient analysis, and radiation detection. You will lead and own nuclear engineering initiatives and studies, strategic direction, and work closely with a collaborative nuclear and engineering team in a fast-paced startup environment. The ideal candidate is passionate about advanced reactor design, detail-oriented, effectively communicates, and a tenacity to solve interesting technical challenges.Responsibilities &amp; Duties  <ul><li>Ownership of Nuclear design and analysis, examples include: </li><ul><li>Shielding: Operational dose and shutdown activation analysis, waste categorization, and alignment of shielding design to customer and regulatory requirements </li><li>Neutronics: Analysis of ex-vessel reactor fluxes and energy deposition, criticality safety, and verification and validation (V&amp;V) of the nuclear toolbox and reactor models</li><li>Accident and Dose Consequence: Radiological dose consequence from different accident scenarios for the Kaleidos demonstration and production units</li><li>Transient Analysis: Run coupled neutronics and thermal calculations to further understanding of the reactor dynamics of the Kaleidos reactor design </li></ul><li>Collect requirements, provide expertise and feedback to engineers in other functional areas via clear, constructive communication. </li><li>Other nuclear design and analysis duties as assigned </li></ul>Required Qualifications &amp; Skills <ul><li>Bachelor’s degree in nuclear engineering or equivalent degree from an accredited institution</li><li>1-2+ years of nuclear engineering industry experience (MS equivalent to 2 yrs).</li><li>Experience with radiation transport methods, including with codes such as MCNP/OpenMC/Serpent</li><li>Proficient in at least one of the following programming languages: Python, C++, C#, FORTRAN, or another scientific computing language </li><li>Basic knowledge of thermal hydraulic principles.</li><li>Self-motivated with strong organizational, written, and oral communication skills  </li><li>Experience working in an engineering organization and developing high-quality work</li></ul>Desired Qualifications &amp; Skills  <ul><li>Experience with variance reduction techniques and associated software (Attila4MC and/or ADVANTG) is a plus</li><li>Strong experience with OpenMC, Serpent, MCNP, Attila4MC, MOOSE, RELAP, Pronghorn, GRIFFIN, or other similar nuclear software packages   </li><li>Competency in distributed software development processes and high-performance computing environments</li><li>Familiarity with CAD design software (NX, SolidWorks, and/or SpaceClaim) is a plus</li><li>Familiarity with dose consequence methods and software such as MAACS or NRC-RADTRAN</li><li>At least 1 year of software development or scripting experience</li><li>Hands-on experience designing hardware and/or performing tests </li></ul>Additional Requirements<ul><li>Must be willing to work extended hours and weekends as necessary to accomplish our mission.</li><li>Must work 100% onsite at El Segundo HQ.</li></ul><div>Total Compensation and BenefitsRadiant's new hire compensation package includes base salary, substantial equity grants, and comprehensive benefits. Total compensation and level are determined through a holistic evaluation of your interview performance, experience, education, and qualifications. Benefits and Perks for Eligible Employees:<ul><li>Stock: Substantial incentive stock plan for all full-time employees.</li><li>Medical: 100% premium coverage for base Silver level plan for employee + 50% premium coverage for dependents. Platinum plans available.</li><li>One Medical: Sponsored memberships for eligible employees and their dependents.</li><li>Vision: 100% premium coverage for top tier plan + 50% for dependents.</li><li>Dental: 100% premium coverage for top tier plan (including orthodontia) + 50% for dependents.</li><li>Voluntary life, accident, hospital, critical illness, commuter and FSA/HSA are offered as employee contributed benefits.</li><li>8-weeks of paid parental leave for all parents. Additional paid pregnancy leave for CA employees.</li><li>Daily catered lunch. Free snacks and drinks.</li><li>Flexible PTO policy. Remote workday allocation.</li><li>Company and team-bonding events, happy hours and in-person camaraderie.</li><li>Beautiful El Segundo headquarters close to the Pacific Ocean.</li></ul>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. </div>

Radiant is a clean energy startup building a nuclear microreactor. A climate-friendly alternative to diesel generators, Radiant's Kaleidos 1MW microreactor will be the world's first portable, zero-emissions power source that works anywhere. We plan to test our development reactor by 2026 and if successful, it will be the first new commercial reactor design to achieve a fueled test in over 50 years. Our microreactor can bring power to remote parts of the world and provide backup power for life-saving applications in hospitals or disaster-relief scenarios.&nbsp;

Nuclear Engineer

<div>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.</div>Nuclear EngineerRadiant is seeking a highly motivated nuclear engineer responsible for developing nuclear engineering solutions for our Kaleidos microreactor. This may include nuclear engineering areas such as radiation shielding, criticality safety, accident dose consequence, reactor physics modeling and design, transient analysis, and radiation detection. You will lead and own nuclear engineering initiatives and studies, strategic direction, and work closely with a collaborative nuclear and engineering team in a fast-paced startup environment. The ideal candidate is passionate about advanced reactor design, detail-oriented, effectively communicates, and a tenacity to solve interesting technical challenges.Responsibilities &amp; Duties &nbsp;<ul><li>Ownership of Nuclear design and analysis, examples include:&nbsp;</li><ul><li>Shielding: Operational dose and shutdown activation analysis, waste categorization, and alignment of shielding design to customer and regulatory requirements&nbsp;</li><li>Neutronics: Analysis of ex-vessel reactor fluxes and energy deposition, criticality safety, and verification and validation (V&amp;V) of the nuclear toolbox and reactor models</li><li>Accident and Dose Consequence: Radiological dose consequence from different accident scenarios for the Kaleidos demonstration and production units</li><li>Transient Analysis: Run coupled neutronics and thermal calculations to further understanding of the reactor dynamics of the Kaleidos reactor design&nbsp;</li></ul><li>Collect requirements, provide expertise and feedback to engineers in other functional areas via clear, constructive communication. </li><li>Other nuclear design and analysis duties as assigned&nbsp;</li></ul>Required Qualifications &amp; Skills&nbsp;<ul><li>Bachelor’s degree in nuclear engineering or equivalent degree from an accredited institution</li><li>1-2+ years of nuclear engineering industry experience (MS equivalent to 2 yrs).</li><li>Experience with radiation transport methods, including with codes such as MCNP/OpenMC/Serpent</li><li>Proficient in at least one of the following programming languages: Python, C++, C#, FORTRAN, or another scientific computing language&nbsp;</li><li>Basic knowledge of thermal hydraulic principles.</li><li>Self-motivated with strong organizational, written, and oral communication skills &nbsp;</li><li>Experience working in an engineering organization and developing high-quality work</li></ul>Desired Qualifications &amp; Skills &nbsp;<ul><li>Experience with variance reduction techniques and associated software (Attila4MC and/or ADVANTG) is a plus</li><li>Strong experience with OpenMC, Serpent, MCNP, Attila4MC, MOOSE, RELAP, Pronghorn, GRIFFIN, or other similar nuclear software packages&nbsp;&nbsp;&nbsp;</li><li>Competency in distributed software development processes and high-performance computing environments</li><li>Familiarity with CAD design software (NX, SolidWorks, and/or SpaceClaim) is a plus</li><li>Familiarity with dose consequence methods and software such as MAACS or NRC-RADTRAN</li><li>At least 1 year of software development or scripting experience</li><li>Hands-on experience designing hardware and/or performing tests&nbsp;</li></ul>Additional Requirements<ul><li>Must be willing to work extended hours and weekends as necessary to accomplish our mission.</li><li>Must work 100% onsite at El Segundo HQ.</li></ul><div>Total Compensation and BenefitsRadiant's new hire compensation package includes base salary, substantial equity grants, and comprehensive benefits. Total compensation and level are determined through a holistic evaluation of your interview performance, experience, education, and qualifications.&nbsp;Benefits and Perks for Eligible Employees:<ul><li>Stock: Substantial incentive stock plan for all full-time employees.</li><li>Medical: 100% premium coverage for base Silver level plan for employee + 50% premium coverage for dependents. Platinum plans available.</li><li>One Medical: Sponsored memberships for eligible employees and their dependents.</li><li>Vision: 100% premium coverage for top tier plan + 50% for dependents.</li><li>Dental: 100% premium coverage for top tier plan (including orthodontia) + 50% for dependents.</li><li>Voluntary life, accident, hospital, critical illness, commuter and FSA/HSA are offered as employee contributed benefits.</li><li>8-weeks of paid parental leave for all parents. Additional paid pregnancy leave for CA employees.</li><li>Daily catered lunch. Free snacks and drinks.</li><li>Flexible PTO policy. Remote workday allocation.</li><li>Company and team-bonding events, happy hours and in-person camaraderie.</li><li>Beautiful El Segundo headquarters close to the Pacific Ocean.</li></ul>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. </div>

Nuclear Engineer

About the Job

About the Company

Radiant

Similar Jobs

Nuclear Shielding Engineer

Nuclear Shielding Engineer

Summer 2026 Internship - Nuclear Engineer

Summer 2026 Internship - Nuclear Engineer

Health Physicist I-IV

Health Physicist I-IV

Senior Nuclear Engineer

Senior Nuclear Engineer

Engineer IV, Nuclear

Engineer IV, Nuclear

Manager Nuclear Engineering -Civil/Mechanical - Catawba Nuclear Station

Manager Nuclear Engineering -Civil/Mechanical - Catawba Nuclear Station

Engineer VI, Nuclear

Engineer VI, Nuclear

Nuclear Training Maintenance/Technical Instructor Senior - Instrumentation & Control

Nuclear Training Maintenance/Technical Instructor Senior - Instrumentation & Control

Nuclear Training Maintenance/Technical Instructor Senior- Electrical

Nuclear Training Maintenance/Technical Instructor Senior- Electrical

Nuclear Supply Chain Specialist

Nuclear Supply Chain SpecialistNew