Senior Nuclear Thermal-Hydraulics Engineer (Nuclear)

TL;DR

Senior Nuclear Thermal-Hydraulics Engineer (Nuclear Engineering): Leading thermal-hydraulics and coupled physics analysis for the Kaleidos microreactor with an accent on core design, cooling systems, and safety case development. Focus on developing coupled multiphysics models and automating simulation workflows to ensure reactor safety under normal and accident conditions.

Location: 100% onsite at El Segundo, CA

Salary: $139.5K – $224.7K

Company

A startup building the world’s first mass-produced, portable nuclear microreactors to replace diesel generators for critical infrastructure.

What you will do

• Execute thermal-hydraulics analysis to evaluate design and safety performance of reactor systems under normal and accident conditions.
• Develop and apply coupled physics models integrating thermal-hydraulics with neutronics and structural response.
• Identify and implement best practices for reactor thermal-hydraulics and systems-code analysis.
• Build automated workflows to expand simulation capabilities, accuracy, and efficiency.
• Collaborate across reactor physics, mechanical, and safety teams to support licensing and design trade studies.

Requirements

• Bachelor's degree in nuclear engineering, mechanical engineering, physics, or similar field.
• 5+ years of relevant industry or national laboratory experience.
• Experience with thermal-hydraulics analysis and reactor systems codes (e.g., RELAP5, TRACE, CTF/COBRA-TF, SAM, TRANSFORM).
• Experience with high-temperature (500°F+) heat transfer analysis involving conduction, convection, and radiation.
• Must work 100% onsite at El Segundo HQ.
• Must be able to comply with U.S. export controls.

Nice to have

• Experience with coupled multiphysics modeling (e.g., MOOSE, BISON, MARMOT) or neutronics coupling.
• Experience with commercial CFD/FEA tools (STAR-CCM+, Ansys Fluent) and CAD (Siemens NX).
• Prior experience at a national laboratory, reactor vendor, or advanced reactor developer.

Culture & Benefits

• Substantial incentive stock plan for all full-time employees.
• Comprehensive health, vision, and dental insurance (up to 100% coverage for employees).
• Daily catered lunch, free snacks, and drinks.
• Flexible PTO policy and remote workday allocation.
• 8-weeks of paid parental leave.