Oklo

Oct 13, 2026

Senior Mechanical Design Engineer - Reactor Module

HybridUnited States

Santa Clara, California, United States

About the opportunity

Thanks for your interest in Oklo! We are searching for an experienced Mechanical Design Engineer to join our team. We are looking to fill this position immediately. Level (Engineer III / Senior / Staff) will be determined by experience.

Position Description

As a Senior Mechanical Design Engineer at Oklo, you will play a central role in designing the critical hardware that enables our advanced fast reactors to operate safely and reliably. This includes technical ownership of large, multi-component weldments and assemblies that comprise the reactor module within our Aurora powerhouses—ranging from the reactor vessel to various internal support structures and primary coolant flow elements. You will be responsible for advancing these components from conceptual design through detailed design and fabrication readiness, ensuring that every element is engineered for performance, manufacturability, industrial Code compliance, and integration into Oklo’s broader reactor system. You may also be tasked with leading early pre-conceptual design efforts for Oklo's future Powerhouse reactor products. Your work will require deep engagement with cross-functional teams including structural analysts, systems engineers, materials experts, and external design and fabrication partners.

This is a high-responsibility role at the heart of our flagship product. Success in this position requires producing quality mechanical solutions in a fast-paced, startup environment where technical excellence and a collaborative mindset are equally valued.

Specific responsibilities may include

Develop and own the design of complex mechanical components and subsystems within the reactor module
Collaborate cross-functionally with other engineering teams to define design and functional requirements, ensuring compliance with safety regulations and industry codes standards (e.g., ASME BPVC)
Use CAD tools to translate functional requirements into robust designs that meet structural, thermal, and integration constraints
Conduct and participate in design reviews, providing and receiving technical feedback
Rigorously evaluate mechanical designs to identify deficiencies and proactively propose and implement solutions
Generate and maintain detailed 3D CAD models, 2D drawings, and bills of materials using controlled processes in PDM/PLM systems
Coordinate closely with analysis teams to guide and interpret thermal, structural, fatigue, and safety analyses in support of design validation
Perform detailed manufacturability reviews, tolerance studies, and DFM/DFA assessments to prepare components for fabrication and assembly
Create and maintain clear, well-written engineering documentation, including design rationales, functional requirements, reviews of historical designs, and detailed explanations of system architecture and performance
Work closely with fabrication partners to refine designs for cost-effective and practical production
Manage engagements with consultants and engineering firms to support high-fidelity analysis, ASME code compliance, and design maturity advancement
Contribute to continuous improvement of Oklo’s mechanical design processes, tools, and standards through feedback and development of best practices

Minimum Qualifications

Bachelor’s or higher degree in Mechanical Engineering or a related engineering discipline
8+ years of industry experience in mechanical or structural design within sectors such as aerospace, automotive, energy, or industrial equipment
Proficiency in 3D CAD modeling software (e.g., Solidworks, CATIA, NX), including part modeling, large assemblies, and detailed drawings
Experience with design control using PDM/PLM tools (e.g., SolidWorks PDM, ENOVIA, Teamcenter)
Robust understanding of mechanical design principles, including DFM (Design for Manufacturability), DFA (Design for Assembly), and tolerance stack-up analysis
Ability to interpret and produce engineering drawings that apply GD&T in line with ASME Y14.5 or similar standards
Working knowledge of material selection (particularly metals), manufacturing methods, and fabrication techniques
Demonstrated ability to collaborate on cross-functional teams, integrating feedback from analysis, manufacturing, and systems engineering
Strong written and verbal communication skills, with the ability to clearly document and present engineering work

Bonus Qualifications

Experience designing large structural weldments and mechanical joints
Familiarity with the ASME Boiler and Pressure Vessel Code, particularly Sections III or VIII
Background in designing components for high-integrity or safety-critical systems (e.g., nuclear, aerospace, defense, or heavy industry)
Proven ability to lead hardware projects through the full development cycle—from concept and design to testing and production
Comfortable working with external manufacturers and engineering consultants for fabrication and analysis support
Knowledge of large scale fabrication techniques and transportation/handling of large components
Understanding of thermal-mechanical analysis principles, with experience designing for high-temperature environments
Basic knowledge of nuclear fission and radiation effects on materials and components

Competencies

We are looking for a Senior Mechanical Design Engineer that is

Passionate about clean energy
Passionate about making advanced fission a reality
Willing and able to learn quickly
Intrigued by fast reactor technology
Eager to work on a dynamic team, receive constructive feedback, and grow with us
Willing to think differently and do things in new ways
Comfortable in a fast-paced, highly iterative startup environment
Excited to think creatively, critically, and reflectively about the problems they are solving, while not leaning only on what has been done before
Willing to propose novel and creative solutions to technical problems
An excellent writer who can write in modern active voice, so make your cover letter compelling and write it well!
Able to communicate technical content and results verbally

Who you are

A startup person: You aren't driven by titles or hierarchy, and prefer

efficiency to excess process. You don't need or expect to have a lot of guidance but you enjoy working in a fast-paced team. If you prefer the culture and feel of a large organization, that is great, but you likely won’t enjoy working with us! There is plenty of important work and plenty of good opportunities with organizations like that.

Motivated: You are self-motivated. You bring an enthusiasm to the team, and

imbue a sense of passion that goes beyond clocking in and clocking out. This isn’t about a fake or arbitrary “pieces of flair” mentality or lack of work-life balance! It is about being a part of the vision and feeling a part of reaching team goals.

A team-player: Oklo genuinely is a team. We aren’t about taking credit for

ourselves, and we aren’t about pushing blame to others. We do incredible things because we work as a team.

An excellent communicator: We need a person who is not only technically

competent but also a clear and upbeat communicator.

Creative: Being creative means that when things fall outside clear scopes or

processes or problems arise without clear solutions, you are able to identify it as well as invent ways to solve a problem or fill a need without micromanagement. The successful person in this job will not only be creative, but also enjoy being creative and solving open-ended problems which may change day-by-day.

Detail-oriented: This focus is a big part of excellence, consistency, and

quality. Excellent grammar and spelling matter for both good communication as well as the image of the company that we put forward.

About Oklo travel requirements

Oklo requires remote employees to travel to headquarters (Santa Clara, CA) twice a quarter annually, based on business or team needs, including attendance at team meetings, off-sites, and other company events or gatherings. For the first two weeks of onboarding, employees are required to be in person at headquarters in Santa Clara, CA.

About Oklo compensation

Salary: $125,000 - $165,000 (pursuant to level and experience)

Oklo offers flexible time off, equity, competitive pay, 401k, health insurance, FSA, flexible work hours, and other benefits.

This position may involve access to information subject to U.S. export control laws. Only applicants who meet the definition of a U.S. person under applicable laws may be eligible.

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About Oklo Inc.: Oklo Inc. is developing fast fission power plants to deliver clean, reliable, and affordable energy at scale; establishing a domestic supply chain for critical radioisotopes; and advancing nuclear fuel recycling to convert nuclear waste into clean energy. Oklo was the first to receive a site use permit from the U.S. Department of Energy for a commercial advanced fission plant, was awarded fuel material from Idaho National Laboratory, and submitted the first custom combined license application for an advanced reactor to the U.S. Nuclear Regulatory Commission. Oklo is also developing advanced fuel recycling technologies in collaboration with the U.S. Department of Energy and U.S. National Laboratories.

#CHOP: Oklo’s Values

Collaboration: We go further, together. We bring diverse perspectives, listen

actively, and build trust through transparency and respect. We work across disciplines, sharing ownership to turn complex challenges into shared successes.

Humility: We are team players who act for the good of the company and for the

world. We are focused on our mission, not personal recognition.

Ownership: We take pride in what we do and how we do it. We are proactive in

finding solutions and see tasks through to completion. We are committed to delivering on our promises to provide clean, reliable, and affordable energy.

Pathfinding: We chart new ground where no path exists by approaching challenges

with curiosity, courage, and creativity while navigating ambiguity.

Candidates should be aware that employment may be contingent upon successful completion of a drug screening, and employees may be subject to drug testing at any time in accordance with company policy and applicable laws.

RECRUITMENT FRAUD DISCLAIMER

Oklo is aware of recent recruitment fraud attempts targeting job seekers. Please be cautious of anyone claiming to represent Oklo who does not contact you from an official Oklo email address.

All legitimate communications from our recruiting team— including application updates, interview requests, and job offers — will come exclusively from an @oklo.com email. Oklo will never ask for sensitive personal information, payments, or account credentials during the hiring process.

If you receive suspicious outreach or have concerns about the authenticity of any communication claiming to be from Oklo, please contact us through the official channels listed on our website.

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Senior Mechanical Design Engineer - Reactor Module

About the opportunity

Specific responsibilities may include

Minimum Qualifications

Bonus Qualifications

We are looking for a Senior Mechanical Design Engineer that is

Who you are

About Oklo travel requirements

About Oklo compensation

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