Intern - NRad & Nuclear/Systems Engineer - Summer 2027

CFS Energy · Devens, Massachusetts

On-siteInternship Entry Level Nuclear Engineering Systems Engineer

$25 – $38/hr

Posted October 9, 2026·Closes December 9, 2026

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About the Role

About 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 NRad or Nuclear/Systems Engineering Intern

We are looking for talented NRad and Nuclear/Systems Engineering Interns 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.

Opportunities available for currently enrolled college students in all levels of schooling from bachelor’s degree to PhD

Interns must be authorized to work in the United States for any employer

What you'll do:

The NRad intern

Collaborate with engineers on the Nuclear Engineering team to do neutronics calculations (heating, activation, flux, dose, etc) to support the design and operation of SPARC, the scoping of ARC, and any other nuclear engineering needed
Work on projects such as, but not be limited to: Neutronics analyses such as energy deposition in delicate materials or shielding sensitivity studies for diagnostic design
Contribute to the computational development of method and workflows needed to support and optimize different types of neutronics analyses

The Nuclear/Systems Engineering Intern

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
Work on projects such as, but not limited to: participating in Hazard Identification reviews and evaluation of accident scenarios, development and verification of radiation related system requirements, and margin budget development, tracking, and support.

What we’re looking for:

Pursuing an engineering degree with focus in the fields Nuclear Engineering or Mechanical Engineering
Neutron Transport or Neutronics or a Reactor Theory course completed by the start of internship
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
Prior hands-on experience or internships working in a commercial/research fission plant environment or the naval nuclear power program
Optional: experienced in CAD and/or Python/ C++

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

#LI-Onsite

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.