Nuclear Engineer
Radiant
Nuclear Engineer
Radiant
Portable nuclear microreactors replacing diesel generators
Radiant is an El Segundo, CA-based company building the world's only mass-produced, transportable nuclear microreactors. The U.S. grid is under growing strain, with power demand accelerating, driving higher utility costs, rising carbon emissions, and interconnection backlogs. Radiant has a solution, transportable, on-site power. Our first reactor, Kaleidos, is 1 megawatt: small enough to be factory-built, transported by land, sea, or air, and deployed wherever power is needed. 1 MW can power 1000 homes for five years. Ship it back and we refuel for a 20 year operating life. We made energy a product that can be used for critical infrastructure like military bases, data centers, hospitals, and remote sites, as well as the commercial main street businesses that keep America running. Founded in 2020, Radiant is under contract to deliver power to the U.S. Army, Navy and Air Force and has signed pre-order agreements with Equinix, with deployments beginning in 2028.
About the Role
Radiant is seeking a highly motivated Nuclear Engineer to own sensor and instrumentation solutions for our Kaleidos microreactor. This includes radiation detection, neutron flux monitoring, and instrumentation design and qualification for reactor physics, shielding, and safety analysis applications. You will lead and own instrumentation 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 has a tenacity to solve interesting technical challenges.
Responsibilities & Duties
Ownership of sensor and instrumentation design and analysis, examples include:
Radiation Detection: Design, specify, and qualify in-core and ex-core detector systems (fission chambers, ion chambers, and other detector technologies) for neutron flux and radiation monitoring.
Detector Modeling: Support detector response modeling and verification using radiation transport codes to ensure sensor design meets performance requirements.
Environmental Qualification: Evaluate and validate sensor survivability and performance under high-temperature, high-radiation, and accident-condition environments.
Systems Integration: Partner with reactor control and data acquisition (DAQ) engineers to integrate sensor outputs into reactor monitoring, protection, and control systems.
Verification & Validation: Support V&V of instrumentation against customer and regulatory requirements.
Collect requirements, provide expertise and feedback to engineers in other functional areas via clear, constructive communication.
Other nuclear instrumentation and sensor design/analysis duties as assigned.
Required Qualifications & Skills
Bachelor's degree in nuclear engineering or equivalent degree from an accredited institution.
1-2+ years of nuclear engineering industry experience (MS equivalent to 2 yrs), with exposure to radiation detection or instrumentation.
Experience with radiation transport methods, including with codes such as MCNP/OpenMC/Serpent.
Proficient in at least one of the following programming languages: Python, C++, C#, FORTRAN, or another scientific computing language.
Basic knowledge of thermal hydraulic principles.
Self-motivated with strong organizational, written, and oral communication skills.
Experience working in an engineering organization and developing high-quality work.
Desired Qualifications & Skills
Hands-on experience designing, testing, or qualifying sensors/instrumentation in harsh environments (high temperature, high radiation).
Experience with data acquisition (DAQ) systems and integration with reactor control systems.
Experience with variance reduction techniques and associated software (Attila4MC and/or ADVANTG), is a plus.
Competency in distributed software development processes and high-performance computing environments.
Familiarity with CAD design software (NX, SolidWorks, and/or SpaceClaim), is a plus.
Familiarity with dose consequence methods and software such as MAACS or NRC-RADTRAN.
At least 1 year of software development or scripting experience.
Hands-on experience designing hardware and/or performing tests.
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.
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.
Nuclear Engineering Certificate Program: 100% covered educational program with Penn State University, for eligible employees, to rapidly upscale into nuclear.
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 full-time 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: [email protected].
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.
Radiant designs and manufactures portable, factory-built nuclear microreactors for off-grid power. Its Kaleidos unit is a 1 MWe high-temperature gas-cooled reactor that uses TRISO fuel and a helium coolant, packaged in a container-sized module that can be transported by truck, ship, or air for rapid deployment to remote sites. The reactor runs for up to five years between refueling as part of a 20-year lifecycle and operates without water cooling, enabling flexible siting. Radiant differentiates itself through factory production of certified HTGR-based microreactors with an ambitious R-50 factory to enable mass production and fast deployment for energy resilience, military, data centers, and critical infrastructure. The company aims to provide reliable, emissions-free power that replaces diesel and supports resilient energy infrastructure at remote or critical locations.
Explore more opportunities at Radiant