Senior Nuclear Engineer

AdAstra; United States; On-site; USD 140,000 - 190,000; Full time

Benefits offered by this job

Medical/Dental/Vision

401(k) plan

Paid vacation

Parental leave

Stock options

ESPP

Discretionary bonus

Job summary

AdAstra is seeking a Sr. Nuclear Engineer in El Segundo, CA to own end-to-end nuclear design and safety analyses for a first reactor. You will drive core design, fuel cycle, reactivity control, and radiation analyses, advancing models to licensing and first criticality.

Mentorship and technical leadership are emphasized while partnering with cross-functional teams to enable rapid, safe deployment. This direct-hire role targets experienced engineers with a strong track record in nuclear systems,

Qualifications

• Bachelor's degree in nuclear engineering or related technical discipline.
• At least 5 years designing, analyzing, and building complex hardware.
• Experience leading engineers and scoping technical work.

Responsibilities

• Support nuclear core design including fuel assembly, reactivity control, thermal hydraulics, and fuel cycle.
• Own reactivity control design and analysis: control rod worth, shutdown margin, transpient response.
• Perform radiation shielding and release analyses against regulatory limits.
• Collaborate with fluids, structures, components, and manufacturing teams for optimized design.
• Engage with fuel procurement and supply chain to ensure manufacturability.
• Own substantial portion of the nuclear system through initial criticality and deployment.
• Mentor junior nuclear engineers and set technical rigor standards.

Skills

Nuclear design

Reactivity analysis

Radiation shielding

Thermal hydraulics

Technical leadership

Project scoping

Mentorship

Regulatory standards

Education

Nuclear engineering degree

Job description

About the Company

Humanity faces two critical challenges: securing reliable energy for everyone and aggressively lowering our environmental impact. Nuclear fission is the key to solving both at once, and our client is actively developing the technology to rapidly scale the deployment of nuclear fission today.

This is a direct hire, permanent placement position for a client of AdAstra Talent Advisors. This position is based in El Segundo, CA. More company details will be shared during an initial call.

The Opportunity

As the Sr. Nuclear Engineer, you will take end-to-end ownership of the nuclear design and safety analysis of our client's first nuclear reactor -- spanning core design and fuel cycle, reactivity control, and radiation release and dose analysis. You will advance the design from today's working simulation models through design finalization, licensing, and first criticality, and will build the analysis tools and methods needed to do it at unprecedented speed.

You will also own the highest-impact analyses and design decisions while setting the technical bar for the nuclear engineering team. Successful candidates will have previously demonstrated extreme ownership in modeling, analyzing, or de-risking complex physical systems, and will be highly motivated to power humanity with abundant, clean energy.

Responsibilities

• Support key aspects of nuclear core design including fuel assembly design, reactivity control through burnable poisons, chemical, and mechanical shim, thermal hydraulics, and fuel cycle design
• Own reactivity control design and analysis: control rod worth, shutdown margin, reactivity coefficients, chemical and mechanical shim, and transient response
• Perform radiation shielding and release analysis against regulatory limits
• Work closely with fluids, structures, components and manufacturing teams to deliver a highly system-optimized and manufacturable design
• Maintain tight partnerships with fuel procurement supply chain including enrichment service providers and fuel assembly fabricators to ensure high manufacturability of our client's design
• Own a significant portion of the nuclear system through initial criticality, extended full power operations, and fleet-wide commercial deployment
• Provide training and mentorship to junior nuclear engineers, setting the standard for technical rigor across the team

Basic Qualifications

• Bachelor's degree in nuclear engineering, physics, or a related technical discipline
• 5 years of engineering experience designing, analyzing, and building complex hardware

Preferred Skills and Experience

• Strong interpersonal and collaborative skills, enthusiasm for problem solving, and desire to enable abundant clean energy
• 5 years of experience designing and analyzing nuclear systems via professional work experience, project/research-based student experience, or a combination of both
• Experience acting as a technical lead --- scoping work, reviewing designs and analyses, and guiding other engineers to successful outcomes
• Ability to perform trade studies and make clear recommendations using first principles and engineering fundamentals even with partial information
• Experience working at a nimble engineering organization or in a highly technical position that required a scrappy, entrepreneurial manner to accomplish tasks with tight time or budget constraints
• Experience with nuclear system design and analysis, including core geometry, reactivity simulations, depletion analysis, and radiation shielding
• Experience with thermal hydraulics, heat transfer, and fluid flow regimes
• Experience designing to key regulatory standards such as 10 CFR Part 50/52/53
• Experience with radiation release analysis, including source term determination and dispersion analysis

Logistical Requirements

• On-site in El Segundo, CA
• Ability to work extended hours and weekends as necessary
• Ability to travel to suppliers and reactor construction sites in other states as necessary

U.S. Person Requirement

• Requires U.S. Person status per export control regulations (10 CFR Part 810). Candidates who are citizens of countries not on Part 810 Appendix A cannot currently be considered, even with a green card.

Compensation

• Annual base pay of $140,000 - $190,000, plus meaningful early-stage equity
• Compensation is determined by role, level, location, and alignment with market data; individual pay may vary based on job-related skills, education, experience, technical capabilities, and internal equity.

Benefit Highlights

• Comprehensive medical, dental, and vision coverage
• 401(k) retirement savings plan
• Paid vacation and paid parental leave
• Long-term incentives via company stock/stock options, plus an Employee Stock Purchase Plan
• Potential discretionary bonuses

Equal Opportunity

Our client is an equal opportunity employer, evaluating qualified applicants without regard to race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability, or any other legally protected status.

About AdAstra

AdAstra Talent Advisors is a headhunting and talent advising firm focused on the Climate, Space, and Defense sectors of Hard Tech. We specialize in pairing highly technical and executive talent with some of the world's leading Hard Tech startups.