Thermohydraulic Test Engineer - Prototype Leader; Remote

Thermohydraulic Test Engineer at Mersenne Labs Prototype and Test Engineer

Location:

Northern Virginia Overview

The Prototype and Test Engineer is a high-responsibility, hands-on engineering role focused on the design, assembly, and testing of prototype hardware and systems. This position is critical to advancing reactor subsystem validation by converting design concepts into physical test configurations and executing structured test programs. The engineer will support cross-functional teams by ensuring mechanical integrity, test readiness, and traceability of results to design requirements.

This role requires a strong understanding of design-for-testability, mechanical integration, and experimental methods in high-consequence environments.

• 5 - 8 years of relevant experience in mechanical system prototyping, hardware development, and/or system-level testing
• Proficiency in 3D CAD tools and technical drawing creation
• Hands- on experience with instrumentation and data acquisition tools
• Knowledge of thermal-fluid systems, mechanical assembly practices, and basic structural analysis
• Demonstrated ability to work in a multidisciplinary, fast-paced development environment
• B.S. degree in STEM field

• Support the design and integration of mechanical and instrumentation components for prototype systems, including thermal loops, test vessels, support structure, etc.
• Develop 3D models, fabrication drawings, and bills of material to realize test hardware
• Drive design-for-manufacturing and design-for-test outcomes
• Interface with vendors and fabricators to support procurement and build activities

• Assist in developing test plans and procedure to validate component and system-level performance
• Select and integrate instrumentation, data acquisition systems, and control hardware
• Participate in test setup, commission in and safe execution of thermal, pressure, or functional tests
• Record, analyze, and interpret test data and contribute to technical reports and design updates
• Ensure test configuration align with verification objectives and regulatory or safety requirements

• Work directly with team building breakthrough hardware at well-funded, seed-stage hardware startup
• Own critical contributions from day one
• Join a team that moves fast, thinks big, and builds real things

Competitive salary, benefits, and revenue share when a product realized from your idea gets commercialized. Let us know if you’d like a longer version with compensation, benefits, or more about the company.

Location:

Onsite (Washington, DC)

Mersenne is designing the world’s first “forever” generators, with a vision for a radically new form of long-lasting energy for Earth, space, and beyond — moving humanity away from constraints of grid electricity and fossil fuels. To achieve this goal, Mersenne is designing a mass-produced fleet of nano-scale nuclear reactors.

Mersenne is led by accomplished technologists and founders along with a core team of nuclear, material, and mechanical engineers with experience in micro-reactor design and construction from leading facilities. We are hiring for key leadership positions to accelerate engineering milestones and take Mersenne out of incubation. Additionally, we are building a team of regulatory experts and public sector specialists to capitalize on the opportunity in our shifting regulatory environment.

• Competitive salary and performance-based bonuses
• Comprehensive health, dental, and vision insurance
• Flexible working hours and remote work options
• Generous paid time off and holiday schedule
• Professional development opportunities and continuing education support
• Collaborative and inclusive work environment

At Mersenne, you will have the opportunity to be part of a groundbreaking initiative that is set to transform the energy landscape. We value innovation, creativity, and a commitment to relentless excellence. By joining our team, you will work alongside some of the brightest minds in the industry, contribute to meaningful projects, and help shape the future of energy.