Nuclear Engineer, Core Physics

Radiant is an El Segundo CA-based startup building the worlds first mass-produced portable nuclear microreactors. The companys 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. Radiants 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.

Reactor Operations Engineer Nuclear

Radiant is a seeking a nuclear engineer responsible for designing and implementing nuclear-specific testing operations at our 2026 demonstration. You will be responsible for the design of a large portion of the test campaign which includes providing analysis to verify that the proposed testing is both safe and meets the tests objectives. This position will work closely with nuclear engineers to establish test success criteria and systems / operations engineers to implement written procedures.

Responsibilities and Duties:

• Collect testing requirements objectives and success criteria from nuclear engineers.
• Develop procedures that satisfy test requirements within the operational bounds of Kaleidos.
• Perform various reactor physics calculations (neutronic and transient analyses) to verify proposed testing sequence addresses all requirements.
• Document testing procedures and support operator training and control room GUI development.

Required Skills and Qualifications:

• Bachelors degree in nuclear engineering or equivalent degree from an accredited institution.
• 2 years of experience with reactor operations.
• Experience with radiation transport methods including with codes such as MCNP/OpenMC/Serpent.
• Knowledge of thermal hydraulic fundamentals.

Desired Skills and Qualifications:

• 4 years of experience with reactor operations.
• Direct experience as a reactor operator of an existing nuclear reactor.
• Hands-on experience in developing technical procedures human factors engineering or operational interface design.

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.

Total Compensation and Benefits
Radiant compensates people for impact and invests in those who continue to raise the bar. Radiants 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 todays advanced reactor builders dont wait for job postings. They join the winning team. If thats you contact us directly for immediate opportunities: .

Benefits and Perks for Eligible Employees:

• Stock: Substantial incentive stock plan for all full-time employees.
• Medical: 100% premium coverage for base Silver level plan for employee 50% premium coverage for dependents. Platinum plans available.
• One Medical: Sponsored memberships for eligible employees and their dependents.
• Vision: 100% premium coverage for top tier plan 50% for dependents.
• Dental: 100% premium coverage for top tier plan (including orthodontia) 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.

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 applicants capacity to serve in compliance with U.S. export controls.