Senior Nuclear Engineer – Reactor Physics & Modeling

About the role

Radiant is a fast‑growing startup developing portable nuclear micro‑reactors. We are looking for a Senior Nuclear Engineer to lead the development of neutronics modeling and reactor physics calculations that feed our proprietary Digital Twin simulation platform. The role is critical for safety analysis and the commercial launch of the first mass‑produced micro‑reactor.

Key responsibilities

• Design and maintain core neutronics modeling methods supporting transient safety analyses.
• Calculate energy deposition distributions, reactivity coefficients, kinetics parameters and control‑blade worths for integration into Digital Twin models.
• Validate assumptions, assess conservatism and document methods for technical and non‑technical audiences.
• Participate in verification & validation activities of the Digital Twin software.
• Provide expertise for additional nuclear analyses such as shielding and radiation detection across the company.

Required profile

• Bachelor’s degree in nuclear engineering or a related discipline.
• At least 4 years of experience using Monte Carlo nuclear codes (e.g., OpenMC, MCNP, Serpent, SCALE).
• Proven ability to document analysis methods and assumptions clearly.
• Strong programming capability, preferably in Python.
• Self‑motivated, ownership‑driven and able to work extended hours when needed.

Required skills

• Monte Carlo nuclear simulation tools: OpenMC, MCNP, Serpent, SCALE.
• Python programming.
• Reactor kinetics analysis.
• Basic thermal‑hydraulic knowledge.

What we offer

• Competitive full‑time salary and substantial incentive stock plan.
• Opportunity to work on groundbreaking nuclear technology in a dynamic startup environment.
• On‑site work at our El Segundo headquarters.