Nuclear Engineer

Radiant; El Segundo (CA); On-site; USD 120,000 - 180,000; Full time

Benefits offered by this job

Stock plan

Medical benefits

One Medical membership

Vision plan

Dental plan

Paid parental leave

Education program

Daily catered lunch

Flexible PTO

Remote workday allocation

Job summary

Radiant, based in El Segundo, CA, seeks a highly motivated Nuclear Engineer to lead nuclear engineering initiatives for the Kaleidos microreactor. You will work with a tight-knit engineering team on shielding, neutronics, dose consequences, and transient analysis, driving design decisions in a startup environment.

The ideal candidate has a nuclear engineering degree and 1–2+ years of industry experience, with programming skills in Python, C++, C#, or FORTRAN, and familiarity with radiation

Qualifications

• Bachelor’s degree in nuclear engineering or equivalent from an accredited institution.
• 1–2+ years of nuclear engineering industry experience.
• Experience with radiation transport methods using MCNP/OpenMC/Serpent.
• Proficient in Python, C++, C#, FORTRAN, or similar scientific computing language.
• Basic knowledge of thermal-hydraulic principles.
• Strong organizational and written/oral communication skills.
• Experience in an engineering organization and delivering high-quality work.

Responsibilities

• Own nuclear design and analysis, including shielding, safety, and validation.
• Conduct neutronics analyses and verify reactor models (ex-vessel fluxes, energy deposition).
• Assess accident dose consequences for Kaleidos demonstrations and production units.
• Run transient analyses with coupled neutronics and thermal calculations.

Skills

Nuclear engineering

Radiation transport

Python

C++

C#

FORTRAN

Thermal hydraulics

Communication

Team collaboration

Education

Bachelor’s degree in nuclear engineering

Tools

MCNP

OpenMC

Serpent

Job description

About Radiant

Radiant is an El Segundo, CA-based company building the world's only mass-produced, transportable nuclear microreactors. The U.S. grid is under growing strain, with power demand accelerating, driving higher utility costs, rising carbon emissions, and interconnection backlogs. Radiant has a solution, transportable, on-site power. Our first reactor, Kaleidos, is 1 megawatt: small enough to be factory-built, transported by land, sea, or air, and deployed wherever power is needed. 1 MW can power 1000 homes for five years. Ship it back and we refuel for a 20 year operating life. We made energy a product that can be used for critical infrastructure like military bases, data centers, hospitals, and remote sites, as well as the commercial main street businesses that keep America running. Founded in 2020, Radiant is under contract to deliver power to the U.S. Army, Navy and Air Force and has signed pre-order agreements with Equinix, with deployments beginning in 2028.

About the Role

Radiant is seeking a highly motivated Nuclear Engineer responsible for developing nuclear engineering solutions for our Kaleidos microreactor. This may include nuclear engineering areas such as radiation shielding, criticality safety, accident dose consequence, reactor physics modeling and design, transient analysis, and radiation detection. You will lead and own nuclear engineering initiatives and studies, strategic direction, and work closely with a collaborative nuclear and engineering team in a fast-paced startup environment. The ideal candidate is passionate about advanced reactor design, detail-oriented, effectively communicates, and a tenacity to solve interesting technical challenges.

Responsibilities & Duties:

• Ownership of Nuclear design and analysis, examples include:

  • Shielding: Operational dose and shutdown activation analysis, waste categorization, and alignment of shielding design to customer and regulatory requirements.

  • Neutronics: Analysis of ex-vessel reactor fluxes and energy deposition, criticality safety, and verification and validation (V&V) of the nuclear toolbox and reactor models.

  • Accident and Dose Consequence: Radiological dose consequence from different accident scenarios for the Kaleidos demonstration and production units.

  • Transient Analysis: Run coupled neutronics and thermal calculations to further understanding of the reactor dynamics of the Kaleidos reactor design.

• Collect requirements, provide expertise and feedback to engineers in other functional areas via clear, constructive communication.

• Other nuclear design and analysis duties as assigned.

Required Qualifications & Skills:

• Bachelor’s degree in nuclear engineering or equivalent degree from an accredited institution.

• 1-2+ years of nuclear engineering industry experience (MS equivalent to 2 yrs).

• Experience with radiation transport methods, including with codes such as MCNP/OpenMC/Serpent.

• Proficient in at least one of the following programming languages: Python, C++, C#, FORTRAN, or another scientific computing language.

• Basic knowledge of thermal hydraulic principles.

• Self-motivated with strong organizational, written, and oral communication skills.

• Experience working in an engineering organization and developing high-quality work.

Desired Qualifications & Skills

• Experience with variance reduction techniques and associated software (Attila4MC and/or ADVANTG), is a plus.

• Strong experience with OpenMC, Serpent, MCNP, Attila4MC, MOOSE, RELAP, Pronghorn, GRIFFIN, or other similar nuclear software packages.

• Competency in distributed software development processes and high-performance computing environments.

• Familiarity with CAD design software (NX, SolidWorks, and/or SpaceClaim), is a plus.

• Familiarity with dose consequence methods and software such as MAACS or NRC-RADTRAN.

• At least 1 year of software development or scripting experience.

• Hands-on experience designing hardware and/or performing tests.

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.

Benefits and Perks

• Stock: Substantial incentive stock plan for all full-time 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/HSA are offered as employee contributed benefits.

• 8-weeks of paid parental leave for all parents. Additional paid pregnancy leave for CA employees.

• Nuclear Engineering Certificate Program: 100% covered educational program with Penn State University, for eligible employees, to rapidly upscale into nuclear.

• Daily catered lunch. Free snacks and drinks.

• Flexible PTO policy. Remote workday allocation.

• Company and team-bonding events, happy hours and in-person camaraderie.

• Beautiful El Segundo headquarters close to the Pacific Ocean.

Total Compensation and Benefits

Radiant compensates people for impact and invests in those who continue to raise the bar. Radiant’s full-time new hire compensation package includes base salary, substantial equity grants, and comprehensive health benefits. Total compensation and level are determined through a rigorous evaluation of interview performance, experience, education, and qualifications, and are designed to support continued growth as scope, responsibility, and impact expand at Radiant.

The best of today’s advanced reactor builders don’t wait for job postings. They join the winning team.

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.

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.