Senior Nuclear Engineer
Content + Source + Freshness • 14 Dec 2025 • 95% confidence
Offer value
High offer value due to critical involvement in innovative nuclear technology and competitive salary expectations.
- Key role in a groundbreaking clean energy project
- Competitive salary with potential equity benefits
- Requires specialized nuclear engineering skills and extensive experience
Pros
- Pioneering role in revolutionary clean energy startup
- Opportunity to influence modern nuclear technology
- Possibility for substantial equity through stock options
Cons
- Requires extensive experience in a niche engineering field
- Onsite work requirement can limit flexibility
- High-pressure work culture typical of startups
Who it's for
Senior / Expert • Onsite
Good fit
- Experienced nuclear engineers
- Professionals eager to work on innovative projects
- Individuals focused on careers in clean energy technology
Not recommended for
- New graduates or those with little nuclear engineering experience
- Candidates seeking flexible or remote work arrangements
- Those who prefer low-pressure work environments
Motivation fit
Key skills
About the job
Radiant is an El-Segundo, CA-based clean energy startup building a nuclear microreactor. A climate-friendly alternative to diesel generators, Radiant's Kaleidos 1MW microreactor will be the world's first portable, zero-emissions power source that works anywhere. We plan to test our development reactor by 2026 and if successful, it will be the first new commercial reactor design to achieve a fueled test in over 50 years. Radiant's goal is to bring one of the world's first factory-constructed microreactors to market. Our microreactor can bring power to remote parts of the world and provide backup power for life-saving applications in hospitals or disaster-relief scenarios.
Senior Nuclear Engineer
Radiant is seeking a driven Senior Nuclear Engineer to join our team! You will own modeling methods and reactor physics calculations of neutronics parameters such as reactivity, kinetics parameters, and energy deposition distributions used within our cutting-edge custom-made Digital Twin simulation software. You’ll be responsible for assessing conservatism and verifying assumptions within the modeling methods and documenting all results. Because these methods are pivotal in the safety analysis, you will play a key role in the commercialization of the first mass-produced nuclear reactor.
Responsibilities and Duties:
- Own modeling methods of core neutronics and reactor physics calculations supporting Radiant’s transient safety analyses.
- Perform calculations of energy deposition distributions, reactivity coefficients, kinetics parameters, and control blade worths to input into Digital Twin models.
- Verify assumptions and assess conservatism of neutronics models.
- Document methods for both technical and non-technical audiences.
- Assist in Verification & Validation (V&V) efforts for the Digital Twin.
- Review and support other nuclear analyses across the company in reactor physics, shielding, and radiation detection.
Required Skills and Qualifications:
- Bachelor’s degree in nuclear engineering or a similar field from an accredited institution.
- 4+ years of experience with Monte Carlo nuclear engineering software such as OpenMC, MCNP, Serpent, SCALE, etc.
- Experience documenting analysis methods and assumptions.
- Strong programming skills in any language, preferably Python.
Desired Skills and Qualifications:
- Knowledge and experience in reactor kinetics.
- Basic knowledge of thermal hydraulic principles.
- Experience communicating and distilling information with cross-functional teams.
- Driven, self-motivated, and takes ownership of work end to end.
Additional Requirements
- Must be willing to work extended hours and weekends as necessary to accomplish our mission.
- Must work 100% onsite at El Segundo HQ.
Employee Benefits for Eligible Employees:
- Stock: Substantial incentive stock plan for all full time, salaried employees.
- Medical: 100% up to base silver level plan for employee + 50% dependents, offers up to Platinum plans.
- One Medical: Sponsored memberships for employees and their dependents.
- Vision: 100% top tier plan coverage + 50% for dependents.
- Dental: 100% top tier plan coverage, orthodontia extra, 50% for dependents.
- Voluntary Life, Accident, Hospital, Critical Illness, Commuter and FSA are offered as employee contributed benefits.
- Free snacks and drinks onsite.
- Flexible PTO policy.
We are an equal opportunity employer and all qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity or expression, pregnancy, age, national origin, disability status, genetic information, protected veteran status, or any other characteristic protected by law.
Unfortunately, we are unable to provide visa sponsorship at this time. This position involves access to technology that is subject to U.S. export controls. Any job offer made will be contingent upon the applicant’s capacity to serve in compliance with U.S. export controls.
