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Radiant is building the world's first mass-produced, portable nuclear microreactors. The company's flagship product, Kaleidos, is a 1-megawatt, fail-safe microreactor designed for rapid deployment to hospitals, data centers, remote sites, and military bases. Founded in 2020 and headquartered in El Segundo, CA, Radiant is preparing to test its first reactor at Idaho National Laboratory with initial customer deliveries expected in 2028.
As a Nuclear Engineer, you will own nuclear design and analysis initiatives for the Kaleidos microreactor across multiple technical domains. Your responsibilities include radiation shielding analysis (operational dose, shutdown activation, waste categorization), neutronics analysis (ex-vessel reactor fluxes, criticality safety, model verification and validation), accident and dose consequence analysis for demonstration and production units, and transient analysis using coupled neutronics and thermal calculations to understand reactor dynamics.
You will collect requirements, provide technical expertise and feedback to engineers across functional areas through clear communication, and take ownership of assigned nuclear design and analysis duties. This is a hands-on technical role in a fast-paced startup environment where you'll work closely with a collaborative nuclear and engineering team.
Required qualifications include a bachelor's degree in nuclear engineering or equivalent, 1-2+ years of nuclear engineering industry experience (master's degree counts as 2 years), experience with radiation transport codes (MCNP, OpenMC, Serpent), proficiency in Python, C++, C#, FORTRAN, or similar scientific computing languages, basic thermal hydraulic knowledge, and strong communication skills.
Desired qualifications include experience with variance reduction techniques (Attila4MC, ADVANTG), advanced nuclear software packages (MOOSE, RELAP, Pronghorn, GRIFFIN), distributed software development and high-performance computing, CAD design software (NX, SolidWorks, SpaceClan), dose consequence methods (MAACS, NRC-RADTRAN), software development or scripting experience, and hands-on hardware design or testing experience.
The role requires 100% onsite work at El Segundo headquarters and willingness to work extended hours and weekends as needed. Radiant offers substantial equity grants, comprehensive health benefits (medical, vision, dental), 8 weeks paid parental leave, daily catered lunch, flexible PTO, and a collaborative team environment near the Pacific Ocean.
