Senior Fuel Cycle and Blanket Mechanical Engineer

Fusion Energy Base; Harvard (MA); On-site; USD 110,000 - 185,000; Full time

Benefits offered by this job

Equity

13 Company-wide Holidays

Flexible vacation days

10 sick days

Parental leave policy

Health, dental, and vision insurance

401(k) with employer matching

Professional growth opportunities

Team-building activities

Job summary

Commonwealth Fusion Systems seeks a Senior Mechanical Engineer to drive the design of molten salt process equipment and high-temperature systems for fuel cycle and blanket development at the Devens site. You will lead specifications, coordinate with suppliers, and ensure safe, reliable performance across scales.

The role requires 8+ years in mechanical engineering, ASME/B31.3 expertise, and experience with fixed equipment in heavy industry, with emphasis on safety and cross-team collaboration.

Qualifications

• Bachelor's degree in Chemical or Mechanical Engineering or equivalent.
• 8+ years of relevant work experience in high-temperature process equipment design.
• Detailed knowledge of ASME BPVC and B31.3 for piping systems.
• Experience with fixed equipment design in refinery/chemical/heavy industry.
• Familiarity with P&IDs, CAD, and process flow diagrams.
• Strong safety-focused design approach.

Responsibilities

• Lead design of fluid process systems for molten salt testing at varying scales.
• Develop specs for high-temp molten salt equipment (vessels, tanks, valves, piping).
• Interface with suppliers/construction teams to procure, install and Commission equipment.
• Support reliability of fixed equipment in later project stages.
• Assist with pipe stress evaluations with piping engineers.
• Collaborate across teams to incorporate R&D learnings into designs.
• Engage with suppliers and contractors with safety as a priority at all stages.

Skills

Mechanical engineering

High-temperature equipment

ASME BPVC & B31.3

P&IDs & CAD

Safety-first mindset

Project coordination

Cross-functional collaboration

Communication & Documentation

Education

Bachelor's degree in Mechanical or Chemical Engineering

Tools

ASME Sections I & VIII

API 510/570/579

Process simulation & piping design tools

Job description

Senior Fuel Cycle and Blanket Mechanical EngineerDevens, MAR&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 Senior Fuel Cycle and Blanket Mechanical Engineer 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:

• Lead and contribute to the design of fluid process systems for testing at varying scales
• Develop specifications and designs of high-temperature molten salt process equipment, including vessels, tanks, valves, pumps and piping systems
• Be the technical lead interfacing with suppliers and construction teams to procure, install and commission process equipment
• At later project stages, support fixed equipment mechanical reliability
• Support pipe stress evaluations working with piping stress engineers
• Collaborate across CFS teams to incorporate R&D learnings and interfacing system requirements into component designs and specifications
• Actively engage with suppliers, contactors and CFS teams to put safety first at all project stages
• Track projects and tasks against milestones and report progress up and across the organization

What we’re looking for:

Bachelors degree in Chemical Engineering, Mechanical Engineering, or equivalent 8+ years of work experience Detailed knowledge of ASME BPVC and B31.3 and their use in designing process equipment and piping systems Design of industrial scale fixed equipment Design of higher temperature equipment and components Management of external partners and suppliers Design for hazardous fluid service Experience at a refinery, chemical plant, or heavy industrial facility preferred Familiarity with design/construction codes and standards such as ASME Section I, ASME Section VIII, ASME B31.3, API 510, API 570 AND API 579 preferred Familiarity with P&IDs, CAD, process flow diagrams, analysis such as heat and mass balances Strong commitment to designing for and working in a safety-prioritized environment. 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:

• Experience with corrosive fluid systems
• Experience with rotating equipment design, procurement, installation, commissioning and reliability.
• Experience with molten salt systems
• Experience with electro-chemical systems
• Analysis of pipe stress and support systems
• Analysis of vessel nozzle loads and stresses
• CAD software

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

$110,000 - $185,000 a yearSalary 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