Senior Nuclear Engineer - Multiphysics Reactor Design (Onsite)

Radiant, an El Segundo, CA-based startup, seeks a Staff Nuclear Engineer to lead nuclear design and analysis of Kaleidos. You will own complex reactor physics workstreams, develop high-fidelity transport models, and drive regulatory documentation. This role requires deep technical judgment, autonomy, and collaboration across disciplines to translate analyses into practical reactor design decisions. You will mentor engineers, establish standards, and contribute to testing, startup, and regulatory