Intern - Nuclear/Systems Engineer - Summer 2027

Commonwealth Fusion Systems LLC; Harvard (MA); On-site; USD 34,000 - 52,000; Part time

Job summary

Commonwealth Fusion Systems LLC in Devens, MA is seeking a Nuclear/Systems Engineering Intern for Summer 2027. The 13-18 week program runs 40-50 hours per week at a set hourly salary, with on-site opportunities and team-based projects that link nuclear and systems engineering.

You will work on neutronics analyses, hazard reviews, and radiation system requirements, collaborating with teams to advance fusion power plant design.

Qualifications

• Pursuing an engineering degree with focus in Nuclear or Mechanical Engineering.
• Available to start during summer 2027 and on-site at Devens, MA.
• Experience with MCNP or OpenMC.
• Strong communication and teamwork skills.
• Prior hands-on projects or internships in nuclear contexts preferred.

Responsibilities

• Support the interface of Nuclear and Systems Engineering teams on neutronics analyses.
• Assist in development and verification of radiation-related system requirements.
• Contribute to hazard reviews and accident scenario evaluations.

Skills

Strong communication skills

Teamwork

Self-motivated

Troubleshooting

Education

Engineering degree (Nuclear or Mechanical)

Tools

MCNP

OpenMC

Job description

Intern - Nuclear/Systems Engineer - Summer 2027Devens, MAInternships /Internship /On-siteAbout Commonwealth Fusion Systems: Commonwealth Fusion Systems is on a mission to deliver the urgent transition to fusion energy. Combining decades of research, top talent, and new technologies, we’re designing and building commercially viable fusion power plants. And we're working with policymakers, suppliers, and many others to build the energy industry of the future. We’re in the best position to make it happen. Since 2018, we’ve raised $4 billion of capital, making us the largest and leading fusion company in the world. Now we’re looking for more thinkers, doers, builders, and makers to join us. People who’ll bring new perspectives, solve tough problems, and thrive as part of a team. If that’s you and this role fits, we want to hear from you. Join the power movement as a Nuclear/Systems Engineering Intern We are looking for a talented Nuclear/Systems Engineering Intern to join our team! CFS interns are highly valued within the organization and placed into meaningful and challenging roles.

Program Details:

13-18 week internship 40-50 hours per week with set hourly salary based on year in school Opportunities on site in Devens, MA. If an intern is going to be on site, you will be responsible for your own transportation and housing Specific project assignments and required technical skillset will vary based on the team’s existing need.

What you’ll do:

The Nuclear/Systems Engineering Intern will support the interface of Nuclear Engineering and Systems Engineering working collaboratively with both teams on neutronics analyses and their application to the development of system design.

• participating in Hazard Identification reviews and evaluation of accident scenarios
• development and verification of radiation related system requirements
• margin budget development, tracking, and support

What we’re looking for:

• Pursuing an engineering degree with focus in the fields of Nuclear Engineering or Mechanical Engineering
• Have complete by the start of their internship
• Neutron Transport or Neutronics or a Reactor Theory course
• Experienced in MCNP or OpenMC
• Experience in Mechanical Design through courses, previous internships, or class projects
• Strong communication skills and a willingness to learn
• Must work well in a team
• Must be highly self-motivated and driven to execute quickly with excellent troubleshooting/problem-solving skills
• Optional: experienced in CAD and/or Python/ C++)
• Prior hands‑on experience or internships working in a commercial/research fission plant environment or the naval nuclear power program

Must-have Requirements:

• Willingness to travel or work required nights/weekends/on‑call occasionally
• Perform activities such as typing, standing, or sitting for extended periods of time
• Dedication to safety to mitigate industrial hazards that may include heat, cold, noise, fumes, strong magnets, lead (Pb), high voltage, and cryogenics

Salary:

$25 - $38 an hour

Rates are aligned to your current year in school, ensuring equitable and consistent pay across our intern program.

For BS interns, the hourly rate is $25–$32

For MS/PhD interns, the rate is $35–$38

Benefits included for full‑time interns:

• 40 hours of sick time
• Health, dental, and vision insurance
• 401(k) with employer matching (must be 21 years of age to enroll)
• Professional growth opportunities
• Team‑building activities

At CFS, we excel in fast‑paced environments, driven by our values of integrity, execution, impact, and self‑critique. As we grow, we’re eager to bring on mission‑driven folks who offer diverse perspectives and fresh ways to tackle challenges.

We value diversity deeply and are proud to be an equal opportunity employer by choice. We consider all qualified applicants equally, regardless of race, color, national origin, ancestry, citizenship status, protected veteran status, religion, physical or mental disability, marital status, sex, sexual orientation, gender identity or expression, age, or any other basis protected by law.

This role requires compliance with U.S. laws concerning the export of controlled or protected technologies or information (collectively, “Export Control Laws").

Any offer of employment will be contingent on the need for compliance with such Export Control Laws.