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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, capable of running for up to 5 years without refueling. Founded in 2020, Radiant is preparing for its first reactor demonstration at Idaho National Laboratory in summer 2026, with initial customer deliveries expected in 2028.
As Nuclear Engineer, Core Physics, you will design and implement nuclear-specific testing operations for the 2026 demonstration. You will be responsible for a large portion of the test campaign, including analysis to verify that proposed testing is both safe and meets test objectives. Working closely with nuclear engineers and systems/operations engineers, you will establish test success criteria and implement written procedures.
Key responsibilities include: collecting testing requirements, objectives, and success criteria from nuclear engineers; developing procedures that satisfy test requirements within Kaleidos' operational bounds; performing reactor physics calculations (neutronic and transient analyses) to verify proposed testing sequences address all requirements; and documenting testing procedures while supporting operator training and control room GUI development.
Required qualifications: Bachelor's degree in nuclear engineering or equivalent from an accredited institution; 2+ years of experience with reactor operations; experience with radiation transport methods including codes such as MCNP, OpenMC, or Serpent; and knowledge of thermal hydraulic fundamentals.
Desired qualifications include 4+ years of reactor operations experience, direct experience as a reactor operator at an existing nuclear reactor, and hands-on experience developing technical procedures, human factors engineering, or operational interface design.
The role requires 100% onsite work at El Segundo headquarters and willingness to work extended hours and weekends as necessary. Radiant offers substantial equity grants, comprehensive health benefits (medical, vision, dental), 8 weeks of paid parental leave, daily catered lunch, flexible PTO, and a collaborative team environment near the Pacific Ocean.
