Senior Mechanical Design Engineer — ASME Section III

About Aalo Atomics

Aalo Atomics is pioneering a new era in clean energy with factory-fabricated microreactors designed to deliver affordable, scalable, and reliable nuclear power. Our mission is to make nuclear energy globally accessible, starting with the Aalo-1, a 10 MWe reactor leveraging cutting-edge safety, modularity, and efficiency. Based in Austin, TX, we’re rapidly growing as we work to deploy the world’s first fleet of advanced microreactors. Join us and help revolutionize energy for a sustainable future.

About the Role

Aalo Atomics is seeking a Senior Mechanical Design Engineer with expert knowledge of ASME BPVC Section III to lead design of reactor vessel and pressure-boundary systems for our sodium-cooled, graphite-moderated reactor.

This hands-on role is for an independent engineer who can contribute immediately in a fast-paced startup environment. You will develop code-compliant designs, supporting analyses, and technical documentation while partnering with manufacturing, materials, quality, and licensing teams.

In addition to reactor pressure vessel design, you will play a central role in Aalo’s ASME certification efforts—supporting demonstration projects for our N, G, and GC stamps and establishing the Section III design and compliance framework that underpins our path to fabrication.

Responsibilities

Section III Design & Code Compliance

• Lead mechanical design and ASME BPVC Section III compliance for reactor vessels, pressure-boundary components, supports, and penetrations.

• Perform and own Section III code calculations for pressure, thermal, fatigue, buckling, seismic, and other design-basis and service-level loads.

• Classify components and systems per NCA/NB/NC/ND requirements, establishing the design classification framework for reactor pressure-boundary and safety-related equipment.

• Apply Section III rules (Subsections NB, NC, ND, NF, and NE as applicable) to pressure vessels, piping, supports, and containment structures, ensuring correct load combinations, stress limits, and service-level criteria.

• Develop Design Specifications, Design Reports, and Overpressure Protection Reports in accordance with Section III requirements.

• Evaluate elevated-temperature design considerations including creep, creep-fatigue, and thermal ratcheting where applicable.

ASME Stamp Certification

• Support demonstration projects for ASME N-stamp (nuclear vessels), G-stamp (nuclear supports), and GC-stamp (nuclear containment vessels).

• Develop the technical deliverables, procedures, and documentation required for stamp certification, including Quality Assurance program support, Design Reports, and coordination with the Authorized Nuclear Inspector (ANI).

• Work with quality and manufacturing teams to establish compliant fabrication, examination, and testing processes that satisfy stamp requirements.

Design Execution

• Own designs from concept through release, fabrication support, testing, and verification.

• Create CAD models, drawings, specifications, and calculation packages.

• Partner with cross-functional teams (manufacturing, materials, quality, licensing) to resolve design, fabrication, and compliance challenges.

• Lead design reviews and communicate technical assumptions, risks, and trade-offs.

• Support prototype builds, supplier engagement, fabrication issues, and testing.

Basic Qualifications

• Bachelor’s degree in Mechanical Engineering or a related discipline.

• 7+ years of relevant mechanical design experience with pressure vessels, pressure-retaining equipment, or nuclear mechanical systems.

• Expert knowledge of ASME BPVC Section III and its application to pressure-boundary design, including familiarity with Subsections NCA, NB, NC, ND, and NF.

• Demonstrated experience with Section III design classification (safety class, seismic category, quality group) and the application of code rules to establish design requirements.

• Experience performing or reviewing Section III code calculations, including stress analysis, fatigue evaluation, and load-combination assessments.

• Experience designing vessels, shells, heads, nozzles, penetrations, flanges, or similar structures.

• Strong understanding of pressure-vessel mechanics, fatigue, buckling, thermal stress, and load combinations.

• Ability to independently drive ambiguous technical work to documented engineering decisions.

• Proficiency with 3D CAD and FEA or structural-analysis tools.

• Ability to work on-site in Austin, TX or Idaho Falls, ID.

Preferred Experience

• Experience supporting ASME stamp certification (N, G, GC, NPT, or NA) including demonstration project planning, ANI coordination, and Design Report preparation.

• Experience designing nuclear components in accordance with ASME BPVC Section III.

• Experience with sodium-cooled, liquid-metal, high-temperature, or other advanced reactor systems.

• Familiarity with elevated-temperature design, creep-fatigue, thermal transients, and high-temperature alloys (including ASME Section III Division 5 or Code Case N-47/N-861).

• Experience developing Design Specifications, Design Reports, and Overpressure Protection Reports per Section III.

• Experience with stainless steels, nickel-based alloys, weldments, and high-temperature fabrication.

• Familiarity with ASME BPVC Sections II, V, IX, and XI.

• Experience supporting fabrication, welding, inspection, pressure testing, or nonconformance resolution.
• PE license is a plus.

Requirements: 

• Based in the United States
• Willing to work on-site in Austin, TX or Idaho Falls, ID.

What We Offer:

• Competitive salary based on technical level
• Health, Dental, Vision Insurance
• Paid Time Off
• Corporate Gym Membership

Additional Information: 

Aalo Atomics provides a collaborative and supportive work environment, opportunities for professional growth, intellectually challenging careers, and competitive compensation. Aalo Atomics is an equal opportunity employer and considers all employment decisions without regard to race, color, religion, national or ethnic origin, sex, sexual orientation, gender identity or expression, age, disability, veteran status, or any other characteristic protected by law.

Applicants must be U.S. Citizens or U.S. Persons in compliance with 10 CFR Part 810 and may not hold non-compliant foreign citizenships.

Direct applicants only. No recruiters or staffing agencies, please.