About Radiant

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 driven Senior Nuclear Engineer to join our team! You will own modeling methods and reactor physics calculations of neutronics parameters such as reactivity, kinetics parameters, and energy deposition distributions used within our cutting-edge custom-made Digital Twin simulation software. You’ll be responsible for assessing conservatism and verifying assumptions within the modeling methods and documenting all results. Because these methods are pivotal in the safety analysis, you will play a key role in the commercialization of the first mass-produced nuclear reactor.

Responsibilities & Duties:

Own modeling methods of core neutronics and reactor physics calculations supporting Radiant’s transient safety analyses.

Perform calculations of energy deposition distributions, reactivity coefficients, kinetics parameters, and control blade worths to input into Digital Twin models.

Verify assumptions and assess conservatism of neutronics models.

Document methods for both technical and non-technical audiences.

Assist in Verification & Validation (V&V) efforts for the Digital Twin.

Review and support other nuclear analyses across the company in reactor physics, shielding, and radiation detection.

Required Qualifications & Skills

Bachelor’s degree in nuclear engineering or a similar field from an accredited institution.

4+ years of experience with Monte Carlo nuclear engineering software such as OpenMC, MCNP, Serpent, SCALE, etc.

Experience documenting analysis methods and assumptions.

Strong programming skills in any language, preferably Python.

Desired Qualifications & Skills

Knowledge and experience in reactor kinetics.

Basic knowledge of thermal hydraulic principles.

Experience communicating and distilling information with cross-functional teams.

Driven, self-motivated, and takes ownership of work end to end.

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.

Benefits and Perks

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.