Nuclear Engineer, Sensors

About Radiant Radiant is an El Segundo, CA-based startup building the world’s first mass-produced, portable nuclear microreactors. The company’s first reactor, Kaleidos, is a 1-megawatt, fail-safe microreactor that can be transported anywhere power is needed and run for up to 5 years without refueling. Portable nuclear power with rapid-deploy capability can replace similar-sized diesel generators and provide critical asset support for hospitals, data centers, remote sites, and military bases. Radiant’s unique, practical approach to nuclear development leverages modern software engineering to rapidly deliver safe, factory-built microreactors that use existing, well-qualified materials. Founded in 2020, Radiant is on track to test its first reactor at the Idaho National Laboratory this summer, with initial customer deliveries beginning in 2028.

Radiant is seeking a highly motivated Nuclear Engineer to own sensor and instrumentation solutions for our Kaleidos microreactor. This includes radiation detection, neutron flux monitoring, and instrumentation design and qualification for reactor physics, shielding, and safety analysis applications. You will lead and own instrumentation 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 has a tenacity to solve interesting technical challenges. Responsibilities & Duties Ownership of sensor and instrumentation design and analysis, examples include: Radiation Detection : Design, specify, and qualify in-core and ex-core detector systems (fission chambers, ion chambers, and other detector technologies) for neutron flux and radiation monitoring. Detector Modeling : Support detector response modeling and verification using radiation transport codes to ensure sensor design meets performance requirements. Environmental Qualification : Evaluate and validate sensor survivability and performance under high-temperature, high-radiation, and accident-condition environments. Systems Integration : Partner with reactor control and data acquisition (DAQ) engineers to integrate sensor outputs into reactor monitoring, protection, and control systems. Verification & Validation : Support V&V of instrumentation against customer and regulatory requirements. Collect requirements, provide expertise and feedback to engineers in other functional areas via clear, constructive communication. Other nuclear instrumentation and sensor design/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), with exposure to radiation detection or instrumentation. 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 Hands-on experience designing, testing, or qualifying sensors/instrumentation in harsh environments (high temperature, high radiation). Experience with data acquisition (DAQ) systems and integration with reactor control systems. Experience with variance reduction techniques and associated software (Attila4MC and/or ADVANTG), is a plus. 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