Staff Fuel Cycle & Blanket Test Engineer

Commonwealth Fusion SystemsDevens, MAJob.bopublished 09/30/2026
Must-have:PythonSeniorLeadPrincipal

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 Senior Mechanical Engineer, Process Equipment

The Fuel Cycle and Blanket Development Team is growing to deliver R&D and pilot-scale molten salt (FLiBe) systems to advance fusion. The technology readiness of FLiBe wetted components is modest due to the challenges of the high operating temperature, different corrosion modes, and the chemistry control required to achieve long term goals. The Fuel Cycle and Blanket Development team is looking for a Senior Mechanical Engineer to drive the design and delivery of molten salt process equipment including ASME tanks, heat exchangers, piping systems and gas processing equipment. This engineer will need to work collaboratively with internal teams at CFS as well as with key external partners to reach ARC’s ambitious technical targets.

CFS engineering teams have a strong practice of carrying engineering risk where appropriate while attentively and aggressively managing safety risk, and we are looking for an engineer who will actively contribute to this culture.

What you'll do: Developing commissioning and test plans for tritium and/or blanket program portfolio test stands

Designing and building infrastructure, both physical and documentation, to enable scaling research and production workflows

Supporting day-to-day needs in test spaces such as safety, cleanliness, procurement, and general upkeep

Providing peer review of procedures, reports, plans, and foundational documents

May be asked to lead and design expanding lab facilities within a team

Building expertise within a growing team, helping scale operations by contributing to training programs, workflows, and best practices

Operation & general upkeep of gas handling & molten salt facility systems & laboratory equipment.

Contribute to integrated system commissioning & build expertise in hazardous material facility operations at a technical level

Contribute to, revise, & author operations procedures

Document facility learnings & contribute to a culture of continuous improvement

What we’re looking for: MS in Engineering (chemical, materials, micro-nano engineering, mechanical engineering with a focus on heat/mass transport), physics, chemistry, or a related field, with 10 years of experience

Experience building and executing testing in an R&D setting

Experience working collaboratively in a laboratory setting with techs and senior scientists

Experience with rigorous data management including programming to generate reports

Experience writing clear lab reports and similar documentation

Generation of formal presentations & ability to succinctly summarize findings for a range of audiences

Attention to detail, safety, and organization to execute tests with good controls

Experience with data analysis using programming tools such as Python

Ability to work effectively in a multidisciplinary team of engineers, scientists, technical staff and others

Ability to clearly express and critique ideas

Excellent communication and organizational skills

Independent problem solving ability, & able to approach new problems with creativity

Bonus points for: 10+ years work experience in a production or laboratory setting

Experience working with high purity, rare, or tritium gases

Experience working with molten salts or corrosive fluids

Glovebox operations & PPE use for hazardous material handling.

Experience with analytical equipment and building high vacuum systems

Confluence, JIRA tools

Experience with process plant systems and ability to read documentation

Must-have requirements: Ability to occasionally lift up to 50 lbs

Perform activities such as typing, standing or sitting for extended periods of time

Willing to occasionally travel to suppliers and support commissioning/test activities

Dedication to safety to mitigate industrial hazards that may include heat, cold, noise, fumes, strong magnets, lead (Pb), high voltage, high current, pressure systems, 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.