Senior TH Safety Analysis Engineer

Deep Fission, Inc

22h • Hybrid

About The Position

Deep Fission is seeking an experienced Senior Engineer to support performance of thermal-hydraulic (T/H) and nuclear safety analyses in support of the design development and licensing of its first-of-a-kind underground pressurized water reactor (PWR). The reactor concept utilizes standard LEU fuel assemblies and conventional PWR thermal-hydraulic conditions, uniquely sited approximately one mile underground. This role sits within the Thermal-Hydraulics Group and represents a key technical contributor to the reactor’s safety analysis program.
The successful candidate will bring hands-on experience with DOE or NRC accepted system-level codes and analysis methodologies applied to licensed PWR applications. In addition to performing design-basis and beyond-design-basis transient and accident analyses, this engineer will help shape Deep Fission’s overall safety analysis and licensing strategy, support code validation and verification (V&V) activities, and develop the reactor system models used for analysis. Because Deep Fission is an early-stage company, this role requires adaptability and a willingness to take on responsibilities across the broader engineering and licensing program as the project evolves.

Requirements

• 7+ years of experience performing nuclear thermal-hydraulic and safety analyses in a licensed nuclear application environment.
• Bachelor’s degree in Nuclear Engineering, Mechanical Engineering, or a closely related technical field.
• Demonstrated proficiency in one or more NRC-accepted T/H system codes applied in licensed PWR applications, including RETRAN, RELAP5 (or RELAP5-3D), TRACE, and/or GOTHIC.
• Experience developing and executing reactor system models for design-basis LOCA and non-LOCA analyses, including model development, nodalization, and steady-state benchmarking.
• Working knowledge of NRC regulatory requirements applicable to safety analysis, including 10 CFR Part 50, Appendix K, the Revised Acceptance Criteria (Best-Estimate LOCA), and associated regulatory guides.
• Familiarity with nuclear quality assurance requirements (e.g., 10 CFR 50 Appendix B, NQA-1) and their application to safety analysis and software V&V.
• Proven ability to prepare and review technical documentation intended for NRC review, including safety analysis calculations, topical reports, or FSAR sections.
• Ability to work effectively in a virtual and hybrid team environment with multiple interfaces and stakeholders.
• Must be a U.S. person eligible to meet DOE Export Control requirements under 10 CFR 810.

Nice To Haves

• Master’s degree or Ph.D. in Nuclear Engineering or Mechanical Engineering.
• Licensed Professional Engineer (PE) in a relevant discipline.
• Direct experience supporting NRC licensing submittals, including topical report preparation, RAI responses, and/or ACRS interactions.
• Experience developing or contributing to a safety analysis methodology program at a reactor vendor, utility, or nuclear engineering firm.
• Familiarity with uncertainty quantification methods (e.g., CSAU, ASTRUM, or similar statistical approaches) for best-estimate T/H analyses.
• Experience with first-of-a-kind nuclear designs, SMRs, or novel licensing pathways (10 CFR Part 52 or emerging 10 CFR Part 53 framework).
• Proficiency with scripting tools (Python, MATLAB) for model automation, post-processing, and sensitivity studies.
• Experience with AI-enabled engineering platforms and modern simulation toolchains.

Responsibilities

• Perform design-basis and beyond-design-basis thermal-hydraulic analyses, including non-LOCA transients, reactivity-initiated accidents (RIAs), loss-of-flow, and station blackout (SBO) scenarios.
• Develop, maintain, and benchmark reactor system models using T/H codes in accordance with applicable regulatory requirements and quality assurance standards.
• Support the development and execution of the Code Validation and Verification (V&V) program, including the preparation of V&V reports and uncertainty quantification in support of NRC licensing submittments.
• Contribute to the development of Deep Fission’s overall safety analysis methodology and licensing strategy, including selection of analysis codes, determination of licensing basis events, and definition of acceptance criteria.
• Prepare and review safety analysis documentation including design-basis accident analyses, safety analysis reports (PSDA/DSA or PSAR/FSAR sections), technical specifications bases, and responses to regulator questions and requests for information.
• Ensure effective coordination with reactor physics, systems, mechanical, and licensing teams to maintain technical alignment across the design and safety basis.
• Participate in design reviews, safety review committee activities, and in-person technical workshops.
• Promote a proactive nuclear safety culture and advocate for Deep Fission and its technology in technical and regulatory forums.
• Perform additional tasks as requested by management, which may include supporting construction, procurement, startup testing, and operational licensing activities as the project matures.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior