Principal Nuclear Engineer – Lead Reactor Physics (Onsite)

Radiant industries; El Segundo (CA); On-site; USD 180,000 - 260,000; Full time

Benefits offered by this job

Stock plan

Medical coverage

One Medical

Vision plan

Dental plan

Parental leave

Lunch provided

Flexible PTO

Team events

Job summary

Radiant, an El Segundo, CA-based startup, seeks a Principal Nuclear Engineer to lead interdisciplinary nuclear engineering work for Kaleidos. You will own analyses across physics, shielding, and safety, translating results into practical reactor design decisions and regulatory documentation.

The role requires strong leadership, 9+ years in nuclear engineering, and deep expertise in neutron transport and Monte Carlo methods. Onsite work at Radiant’s headquarters in California is required.

Qualifications

• Bachelor’s degree in nuclear engineering or related technical discipline.
• 9+ years of nuclear engineering experience across reactor design, analysis, testing, licensing, safety, or operations.
• Experience leading multidisciplinary teams on complex nuclear projects.
• Experience hiring, mentoring, or technically leading nuclear engineers.
• Deep knowledge of neutron transport theory, Monte Carlo methods, nuclear data, and statistical convergence.
• Experience developing and applying MCNP/OpenMC or comparable transport models.
• Strong understanding of criticality, reactivity coefficients, depletion, power distribution, shutdown margin, and uncertainty analysis.
• Ability translating analysis into reactor design decisions, safety conclusions, or regulatory documentation.
• Familiarity with model verification, configuration control, peer review, and nuclear software quality practices.
• Excellent written and verbal communication skills to explain analyses and uncertainties.

Responsibilities

• Lead an interdisciplinary team across reactor physics, core performance, shielding, dose and activation, thermal-hydraulics, safety analysis, I&C, and operations.
• Establish technical priorities, project plans, resources, and ownership across the nuclear engineering org.
• Serve as technical authority for neutron and radiation transport and Monte Carlo methods.
• Own projects from requirements capture to design iteration, analysis, and final documentation.
• Guide analyses of criticality, reactivity, depletion, power distribution, and shielding performance.
• Translate results into actionable design decisions for core, shielding, controls, and instrumentation.
• Establish rigorous practices for verification, peer review, configuration control, and documentation.
• Collaborate with reactor systems, thermal, mechanical, electrical, test, safety, and regulatory teams.
• Translate standards into analysis plans, calculation packages, and verification activities.
• Support reactor testing and startup with analysis needs, instrumentation requirements, and acceptance criteria.
• Identify risks and mentor engineers through guidance and coaching.

Skills

Neutron transport theory

Monte Carlo methods

Technical leadership

Communication skills

Nuclear data

Education

Bachelor’s degree in nuclear engineering or related field

Master’s or PhD in nuclear engineering (preferred)

Tools

MCNP

OpenMC

Nuclear engineering software quality practices

Job description

Radiant, an El Segundo, CA-based startup, seeks a Principal Nuclear Engineer to lead interdisciplinary nuclear engineering work for Kaleidos. You will own analyses across physics, shielding, and safety, translating results into practical reactor design decisions and regulatory documentation.

The role requires strong leadership, 9+ years in nuclear engineering, and deep expertise in neutron transport and Monte Carlo methods. Onsite work at Radiant’s headquarters in California is required.