Senior Software Engineer (HPC)

TL;DR

Senior Software Engineer (HPC): Design and implement robust software systems powering reactor simulation and Digital Twin capabilities with an accent on multi-physics models, high-performance computing, and simulation infrastructure. Focus on architecting thermal, hydraulic, and nuclear simulation systems, integrating third-party tools, and enabling software-in-the-loop testing.

Must work 100% onsite at El Segundo, CA HQ. Subject to U.S. export controls. Unfortunately, no visa sponsorship.

Annual Salary Range $158,000 – $219,450 • Offers Equity

Company

El Segundo, CA-based startup building portable nuclear microreactors, with first reactor testing at Idaho National Laboratory this summer and customer deliveries in 2028.

What you will do

• Implement and contribute to software architecture for simulation systems across thermal, hydraulic, and nuclear reactor multi-physics models.
• Collaborate with simulation engineers on reactor and subsystem physics models.
• Build and maintain infrastructure for Digital Twin simulation, visualization, and data processing.
• Contribute to technical roadmap for thermal and safety analysis simulation, including model tuning strategies.
• Evaluate and recommend third-party tools, libraries, and simulation frameworks.
• Collaborate cross-functionally with hardware, nuclear, and electrical teams on software/hardware-in-the-loop testing.

Requirements

• Bachelor's degree in physics, mechanical engineering, computer science, or similar field.
• 5+ years professional software engineering experience with depth in HPC, computational science, Machine Learning, or related field.
• Expert proficiency in Python, Rust, or C/C++.
• Strong background in simulation tools, physics-based modeling, numerical methods, or computational science.
• Proficiency with visualization frameworks, open source platforms, and automated testing for scientific software.
• Strong software engineering practices: version control, code review, CI/CD.
• Must work 100% onsite at El Segundo HQ and be willing to work extended hours/weekends.
• No visa sponsorship; must comply with U.S. export controls.

Nice to have

• Advanced degree (Master's or Ph.D.) in relevant field.
• Experience in simulation, computational modeling, parallel computing, or HPC projects.
• Background with modern simulation frameworks, finite element analysis, or CFD tools.
• Experience with ML, deep learning, or probabilistic modeling.
• Experience in regulated industries (aerospace, defense, automotive, nuclear, medical).

Culture & Benefits

• Substantial equity for all full-time employees.
• 100% medical up to silver + 50% dependents (up to Platinum); full vision/dental coverage + 50% dependents.
• One Medical memberships, voluntary benefits (life, accident, etc.), FSA/HSA, commuter.
• 8 weeks paid parental leave + extra for CA pregnancy; flexible PTO; remote workday allocation.
• Daily catered lunch, free snacks/drinks, team events, happy hours.
• Beautiful HQ near Pacific Ocean; high-performance engineering culture with knowledge sharing.