Computational Nuclear Engineer

Hitachi, Ltd.; Kearny (NJ); Hybrid; USD 120,000 - 180,000; Full time

Benefits offered by this job

Salary range: $120,000-$180,000

Comprehensive health benefits

Employee equity stock options

20 days PTO

Job summary

Thea Energy is seeking a Computational Nuclear Engineer to advance neutronics and multiphysics simulations for stellarator fusion systems. You will work on high-fidelity transport methods and dose rate calculations in a startup environment.

The ideal candidate has a PhD or Master’s with strong coding skills in Python and C++, plus experience with Monte Carlo codes and multiphysics coupling frameworks. Join a team pushing frontier fusion research.

Qualifications

• PhD in Nuclear Engineering or related field with strong research background in neutronics.

Responsibilities

• Develop and implement high-fidelity neutronics and multiphysics simulations in complex 3D stellarator geometries.
• Simulate fusion blanket performance including TBR, energy deposition, activation, and shielding.
• Enable multiphysics coupling (neutronics to thermal-hydraulics/structure) to refine reactor designs.
• Compute dose rates and design optimized shielding for personnel and equipment.
• Prepare reports, presentations, and publications from simulation results and optimization findings.

Skills

Monte Carlo methods

Python

C++

Git/GitHub

CI/CD

MPI/OpenMP

HPC

Education

PhD in Nuclear Engineering

Master’s in a related field

Tools

OpenMC

MCNP

Serpent

NJOY

MOOSE

Cardinal

NekRS

Job description

About Thea Energy

Thea Energy is leveraging recent breakthroughs in stellarator physics and engineering to create a faster and simpler approach to commercializing fusion energy. The company is reinventing the stellarator using computer-controlled arrays of planar coils thereby replacing the intricate, complex modular magnets required in all other stellarator architectures. Thea Energy is on a mission to create a limitless source of zero emission energy for a sustainable future.

Position Overview

We are seeking a highly motivated Computational Nuclear Engineer to join our team,focusing on neutronics and multiphysics simulations for stellarator fusion systems. The idealcandidate will possess a strong background in computational transport methods, with aparticular emphasis on multiphysics reactor design, dose rate calculations, and radiationshielding optimization. You will work with minimal supervision, contributing to cutting-edgeresearch and development to ensure the safety and performance of Thea Energy’s stellaratorsystems.

Key Responsibility Areas

• Develop and implement advanced workflows for high-fidelity neutronics and related multiphysics simulations in complex 3D stellarator geometries.
• Conduct simulations of fusion blanket performance, including tritium breeding ratios (TBR), energy deposition, material activation, radiation shielding, and more.
• Collaborate with cross-disciplinary teams to perform multiphysics coupling (e.g., neutronics to thermal-hydraulics or structural analysis) to refine reactor designs.
• Perform dose rate calculations and design optimized shielding solutions for personnel and sensitive equipment.
• Prepare technical reports, presentations, and publications based on simulation results and optimization findings.

Ideal Experience & Skillsets

• PhD in Nuclear Engineering, Computational Physics, Applied Physics, or a related field with2+ years of experience; or a Master’s degree in a relevant field with 4+ years of experience.
• Strong knowledge of Monte Carlo radiation transport codes (e.g., OpenMC, MCNP,Serpent).
• Proficiency in programming languages commonly used in scientific computing, specificallyPython and C++.
• Proficiency in modern scientific software development best-practices (e.g. git, GitHub, CI)
• Experience in multiphysics coupling frameworks (e.g., MOOSE, Cardinal, NekRS).
• Excellent analytical, problem-solving, and communication skills.

Preferred Skills

• Experience with nuclear data processing and libraries (e.g., NJOY). Experience with deterministic neutron transport solvers (e.g. Atilla, OpenSN)
• Familiarity with High-Performance Computing (HPC) environments and parallel programming (MPI/OpenMP).
• Background in applying machine learning techniques to optimize nuclear simulation results or data handling.
• Understanding of fusion-specific nuclear challenges, such as first-wall material damage and tritium fuel cycle management.

Personal Attributes

• Ability to work independently and manage projects with minimal supervision in a startup environment.
• Strong attention to detail and a passion for advancing the field of fusion energy research.
• Willingness to collaborate with a diverse team of scientists and engineers within the company and externally.
• Persistent optimism and a willingness to take on tough challenges.
• Excited to think creatively about solutions to difficult problems and not relying solely on what has been done before.

Company Benefits

• Salary range: $120,000-$180,000
• Comprehensive health benefits (e.g. medical/dental/vision)
• Employee equity stock options
• 20 days PTO

Diversity and Inclusion

Thea Energy is an equal opportunity employer committed to creating a company of diverse backgrounds. By creating a diverse environment, we will bring new ideas and approaches to solving some of the world’s hardest (and most important) problems. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, gender, sexual orientation, gender identity or expression, national origin, family or marital status, age, disability, veteran’s status, or other characteristic protected by applicable laws and regulations.