Molten Salt Engineer

Devens, MA
R&D – Technology Development /
Full-time /
On-site
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:

  • Assist in the creation of new in-house experimental setups, including determination of requirements, fabrication, testing, and operation
  • Perform salt characterization testing and work to improve the repeatability and robustness of these processes
  • Perform calibration exercises for various tests, including electrochemical ones
  • Analyze and synthesize heterogeneous sets of data to thoroughly characterize salt quality
  • Contribute to creation of chemical system requirements and material requirements
  • Support experiments and in-loop testing for salt-compatible components (e.g. pumps, valves, heat exchangers)
  • Work with external vendors to procure new equipment and materials
  • Work closely with other CFS teams including:
    • safety team to manage chemical hazards (including beryllium) in existing and new experimental test articles
    • ARC Design Team

What we're looking for:

  • BS in Chemistry, Chemical, Materials or Nuclear Engineering or a related field
  • 5+ years of experience in an R&D environment (PhD program counts)
  • Experience with R&D work in a chemical laboratory
  • Experience in experimental design and analysis with the explicit goal of driving to higher component and system TRLs
  • Experience working with safety systems for hazardous chemicals
  • Experience with modeling tools, such as Calphad, FactSage, Comsol, or similar (preferred, not required)
  • 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:

  • PhD in Chemistry, Chemical Engineering, Materials Engineering, Nuclear Engineering, or related field
  • Experience with electrochemistry or electrochemical engineering
  • Experience with radiochemistry
  • Experience with molten salt systems, particularly fluoride salt systems
  • Experience with high temperature and/or corrosive systems
  • Experience with gas handling systems and gas analysis
  • Experience modeling chemical systems (e.g. reaction, transport, thermodynamic, radiochemical)
  • Experience in setting up new laboratory facilities or new analysis equipment (e.g. GCs)

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
$107,000 - $160,000 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
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.