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Nuclear Engineer I/II (Reactor Design)

Fissionaire

Madison, WI • 9/13/2026

Engineering , Professional

Job Description

Job Description

As an emerging leader in nuclear engineering, our startup is developing revolutionary reactor technology to secure safe and abundant energy for future generations. We are seeking a highly skilled entry-level Nuclear Engineer I/II to join our dynamic team and contribute to the design and development of next-generation nuclear reactors.


TheNuclear Engineer I/II will contribute to the design, analysis, and optimization of advanced nuclear reactor systems. The ideal candidate will have a strong background in nuclear engineering, proficiency with industry-standard design software, and a proactive, self-starting attitude. This role requires innovative thinking, technical expertise, and a commitment to advancing safe and sustainable nuclear energy solutions.

Key responsibilities
  • Design and develop nuclear reactor systems, including core design, thermal-hydraulics, and safety systems, ensuring compliance with regulatory standards.
  • Perform simulations and analyses to optimize reactor performance, safety, and efficiency using industry-standard software tools.
  • Collaborate with multidisciplinary teams, including mechanical engineers, materials scientists, and safety analysts, to integrate reactor designs into broader systems.
  • Conduct risk assessments and safety analyses to ensure designs meet stringent nuclear safety requirements.
  • Prepare technical reports, design documentation, and presentations for internal stakeholders and regulatory bodies.
  • Stay updated on advancements in nuclear technology, materials, and regulations to incorporate cutting-edge solutions into designs.
  • Participate in project planning and scheduling to ensure timely delivery of design milestones.
  • Contribute to research and development initiatives for innovative reactor concepts.
qualifications
  • Master’s degree in Nuclear Engineering or a related field. Ph.D. preferred but not required.
  • Minimum of 1-2 years of experience in nuclear reactor design, analysis, or related fields within industry or in academic work.
  • Proficiency with nuclear design and analysis software, such as MCNP, SCALE, RELAP5, COMSOL, MOOSE, GOTHIC etc.
  • Familiarity with CAD software for reactor component design.
  • Proficiency in programming languages for data analysis, scripting, or automation of design processes.
  • Knowledge of nuclear physics, neutronics, thermal-hydraulics, and reactor safety principles.
  • Experience with Molten Salt Reactor design preferred.
  • Demonstrated ability to work independently, take initiative, and drive projects to completion with minimal supervision.
  • Excellent written and verbal communication skills for technical documentation and cross-functional collaboration.
  • Familiarity with nuclear regulatory frameworks and safety standards.
  • Knowledge of materials science, particularly related to radiation-resistant materials and high-temperature applications.
  • Familiarity with risk assessments and analysis (PRA, FMEA, PIRT etc.) preferred
  • Familiarity with computational fluid dynamics (CFD) for thermal-hydraulic analysis preferred.
  • U.S. citizenship or permanent residency required.
What we offer
  • Competitive salary with equity options
  • Comprehensive benefits, holiday and PTO schedule
  • Opportunity to shape foundational operations in a groundbreaking nuclear startup.

Fissionaire’s technology is subject to U.S. export control regulations, which require the company to review applicants’ eligibility based on their citizenship or residency status. As part of the application process, candidates will be asked to indicate whether they are a U.S. citizen, green card, lawful permanent resident, asylee, or refugee resident to support this review. Because government authorization timelines can vary, Fissionaire is unable to consider alternate resident statuses where required approvals may not be obtainable within a timeframe that meets business needs.

Fissionaire is an Equal Opportunity Employer that does not discriminate on the basis of actual or perceived race, colour, creed, religion, national origin, ancestry, citizenship status, age, sex or gender (including pregnancy, childbirth, pregnancy-related conditions, and lactation), gender identity or expression (including transgender status), sexual orientation, marital status, family or relationship structure, military service and veteran status, physical or mental disability, genetic information, gender identity, or any other characteristic protected by applicable federal, state, or local laws and ordinances. Fissionaire’s management team is dedicated to this policy with respect to recruitment, hiring, placement, promotion, transfer, training, compensation, benefits, employee activities, access to facilities and programs, and general treatment during employment.

We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses and identifying potential inconsistencies or verification signals in application materials based on available information. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us.