Molten Salt Engineer

Commonwealth Fusion Systems
Commonwealth Fusion Systems

Full-time

Devens, MA, USA

USD 70k-120k / year + Equity

Posted on Sep 3, 2026
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 Molten Salt Engineer

Salt chemistry is a critical driver of corrosion, hydrogen speciation, and material behavior under irradiation. As the Blanket System team scales up to larger systems, maintaining precise control over salt chemistry is vital. We are seeking an entry-level Molten Salt Engineer to support our experimental testing operations. Initially, you will focus on executing standard operating procedures (SOPs), conducting routine materials testing, and maintaining rigorous quality controls. As you build familiarity with our systems, your role will expand to include experimental design, test cell design and construction, and leading projects in materials corrosion and blanket health monitoring. Ideal candidates will have a background in chemistry, chemical engineering, or a related discipline.

The Blanket System team has a strong culture of teamwork, supportive safety culture, and pragmatic risk management. We are looking for an engineer who will fit and actively contribute to this culture.

What you'll do:

  • Perform corrosion testing of novel materials in molten salts
  • Perform device testing in molten salts to obtain statistics on device performance
  • Design and build new test cells for molten salt R&D
  • Assist with lab maintenance and upkeep
  • Write and modify SOPs for safe handling of hazardous chemicals, including fluoride salts (FLiBe)

What we're looking for:

    • Bachelors degree in Chemistry, Chemical Engineering, Materials Engineering, Nuclear Engineering, Mechanical Engineering, or similar field
    • 0-2 years of work experience
    • Experience with R&D work in a chemical or engineering laboratory
    • Experience working with safety systems for hazardous chemicals
    • Ability to learn new skills/subject matter quickly
    • Ability to work effectively in a multidisciplinary team of engineers, scientists, technical staff and others
    • Ability to clearly express and critique ideas
    • Great communication and organizational skills
    • Strong problem solving skills, ability to approach new problems with creativity

Bonus points for:

  • High temperature chemistry
  • Molten salts
  • Electrochemistry
  • Ceramics
  • Python, MATLAB, or equivalent for data analysis
  • Building and commissioning new laboratory equipment
  • CAD software

Must-have requirements:

  • Ability to occasionally lift up to 50 lbs
  • Perform activities such as sitting, typing, standing, stooping, or climbing 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
  • Willingness to travel or work required nights/weekends/on-call occasionally
#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.

70000 - 120000 USD a year

Salary range for this full-time position + equity + benefits. The actual salary will depend on level, location, qualifications, and experience. The range displayed on each job posting reflects new hire salaries for the position across all US locations. Benefits include:
• Competitive compensation with equity
• 13 Company-wide Holidays
• Flexible vacation days
• 10 sick days
• Generous parental leave policy
• Health, dental, and vision insurance
• 401(k) with employer matching
• Professional growth opportunities
• Team-building activities
See more open positions at Commonwealth Fusion Systems