Lead Nuclear Engineer: Monte Carlo & Reactor Physics

Radiant; El Segundo (CA); On-site; USD 150,000 - 230,000; Full time

Benefits offered by this job

Stock plan

Health benefits

Medical plan

Vision plan

Dental plan

Life insurance

Parental leave

Lunch provided

Flexible PTO

Remote workdays

Team events

HQ in El Segundo

Job summary

Radiant, an El Segundo, CA-based startup, seeks a Principal Nuclear Engineer to lead interdisciplinary nuclear engineering work for Kaleidos. You will guide design trades, verification, and regulatory documentation, owning projects from requirements to final deliverables.

You will apply deep expertise in neutron transport and Monte Carlo methods, translating analyses into practical reactor design and operations decisions, while mentoring engineers and coordinating with cross-functional teams.

Qualifications

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

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, resource needs, and clear ownership across the nuclear engineering organization.
• Serve as a technical authority for neutron and radiation transport and Monte Carlo simulation methods.
• Own nuclear engineering projects from requirements capture and design iteration through model development, analysis, technical review, and final documentation.
• Guide analyses of criticality, reactivity control, shutdown margin, power distribution, depletion, temperature feedback, radiation transport, dose, activation, and shielding performance.
• Translate analytical results into actionable requirements and design decisions affecting the core, shielding, control systems, instrumentation, fluid systems, and structures.
• Establish technically rigorous practices for model verification and validation, peer review, configuration control, uncertainty evaluation, and documentation.
• Collaborate with reactor systems, thermal, mechanical, electrical, test, operations, safety, and regulatory teams to resolve multidisciplinary design challenges.
• Translate nuclear standards and regulatory requirements into analysis plans, design criteria, calculation packages, and verification activities.
• Support reactor testing and startup by defining analysis needs, instrumentation requirements, acceptance criteria, and methods for comparing predicted and measured performance.
• Identify technical risks, drive complex problems through closure, and communicate decisions and recommendations to engineering teams and company leadership.
• Mentor engineers through technical guidance, actionable feedback, and regular coaching.

Skills

Neutron transport theory

Monte Carlo methods

MCNP/OpenMC

Nuclear data analysis

Leadership

Communication skills

Education

Bachelor’s degree in nuclear engineering

Master’s degree or Ph.D.

Tools

MCNP

OpenMC

Griffin

SCALE

Python

Job description

Radiant, an El Segundo, CA-based startup, seeks a Principal Nuclear Engineer to lead interdisciplinary nuclear engineering work for Kaleidos. You will guide design trades, verification, and regulatory documentation, owning projects from requirements to final deliverables.

You will apply deep expertise in neutron transport and Monte Carlo methods, translating analyses into practical reactor design and operations decisions, while mentoring engineers and coordinating with cross-functional teams.