Director of ModSim

Valar Atomics

Torrance, California

Full Time

Posted September 14, 2026

$225k - $300k

Nuclear Energy

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Listing evidence and provenance

Source: greenhouse View original listing
Freshness: Open in the current public read path; this is not an employer guarantee.Last observed September 29, 2026
Classification: Modern power-system classification not yet published for this listing.Legacy source industry field: Nuclear Energy
Pay provenance: Employer-provided pay

Job Description

The ModSim Engineering Group is a dynamic analysis and engineering group that provides the analytical foundation for reactor and plant design, delivering high-fidelity computational analysis, integrated directly into the engineering design process.

Key Responsibilities

Neutronics and reactor design;
Thermal-hydraulics systems analysis covering steady-state and transient performance of the complete system; and
Computational fluid dynamics and finite element analysis for detailed flow, thermal, and structural integrity assessment.
ModSim works alongside the engineering and licensing organizations and develops and maintains the models that underpin design basis definition, transient and accident analysis, safety case development and regulatory submittals, applying rigorous verification, validation and uncertainty quantification throughout. The group's responsibilities extend beyond prediction: models are benchmarked against test data and against operating data from research and demonstration reactors in construction and service, closing the loop between simulation, as-built plant performance, and the continuous improvement of the company's analytical methods and business case.
The Director of ModSim leads VALAR Atomics’ modeling, simulation, and analysis organization across CFD, FEA, thermal-hydraulics, and nuclear engineering, and is accountable for ensuring that analysis supports the design process and outputs that get built.
Reporting to the CNO / VP of Engineering, the Director of ModSim owns the strategy, quality, throughput, resourcing, and budget of the group; the multiphysics integration and verification-and-validation (V&V) consistency that bind the disciplines together; and the licensing-grade defensibility of every deliverable under a nuclear quality program (i.e. NQA-1, 10 CFR 50 Appendix B, ASME V&V 10/20/30).
In a dynamic, speed-driven start-up racing to deploy reactors at scale, the ModSim Director is equal parts technical authority, org-builder, systems thinker, and dot-connector, growing the team from a small core, automating the simulation-to-design workflow, and wiring ModSim into design, manufacturing, licensing, and construction so that models become steel, on schedule and to code. This is a hands-on-enough leader who is as comfortable interrogating a Flownex transient or a neutronics depletion run as standing on a fabrication floor asking why the as-built diverges from the model.
The Director carries seven areas of accountability, spanning technical leadership, people, integration, reporting, and relentless optimization of output rate, speed, and quality:
Technical leadership across the four core disciplines. Set the analysis strategy, methods, and standards for CFD, FEA, thermal-hydraulics, and neutronics; own multiphysics integration, cross-discipline data-exchange conventions, configuration control, and end-to-end V&V so the coupled picture is consistent and defensible.
Close the loop from model to build hardware. Ensure analysis directly supports design outputs, i.e., sized components, qualified structures, validated systems, and stays connected through procurement, fabrication, construction, and commissioning; drive validation and design-for-manufacture feedback so the digital model and the physical plant stay in alignment.
Build, grow, and develop the team. Recruit, mentor and retain Stream/Discipline Leads and their analysts; scale a small start-up core into a high-performing multidisciplinary group; engage SMEs and external partners; create the culture, career paths and technical bar for the organization.
Integrate ModSim within the wider engineering enterprise. Partner with design, systems engineering, manufacturing, licensing/safety, project management, and construction so that simulation is embedded in the design process rather than bolted on; make ModSim the trusted, single source of analytical truth across groups.
Report to and advise executive leadership. Serve as the senior simulation interface to the CNO / VP of Engineering and executive team; translate complex analysis into clear, decision-grade guidance on risk, schedule, cost, and design choices.
Relentlessly optimize output rate and quality. Drive throughput and rigor together via workflow automation, scripting, templated and parametric models, digital-thread / digital-engineering tooling, HPC scaling, and reusable V&V, etc., so the group delivers more, faster, without compromising nuclear-grade quality.
Own quality, licensing-readiness, tooling, and budget. Hold accountability for the nuclear QA and V&V framework (NQA-1, 10 CFR 50 Appendix B, ASME V&V 10/20/30) and licensing-grade defensibility (NRC 10 CFR Part 50/52/53, ASME codes); manage the simulation software portfolio, HPC resources, vendor relationships and group

Requirements

Master’s degree in engineering (MSc/MEng), or equivalent work experience required — Nuclear, Mechanical, Aerospace, or a closely related discipline; PhD strongly preferred.
15+ years in engineering simulation and analysis, with substantial multidisciplinary leadership and team / program management (a strong 10+-year track record with exceptional build-to-deployment credentials will be considered).
Demonstrated experience taking modeling and analysis through to design, constructed and/or operating hardware – not solely paper studies.
Depth in at least one of CFD, FEA, thermal-hydraulics or neutronics, with the breadth to direct and critically review the others.
Experience working under a formal quality program (NQA-1, ISO 9001, 10 CFR 50 Appendix B or equivalent) and within a regulated environment (NRC, ASME, or comparable such as naval nuclear, aerospace/FAA, or DoD).
S. Person status (or ability to meet U.S. nuclear export-control requirements under 10 CFR Part 810 / ITAR-EAR) and ability to obtain any required DOE/NRC access or clearance.
A strong candidate will bring most of the following – the blend of computational depth, engineering breadth, and delivery credibility this role demands:

Benefits & Perks

Competitive base salary
Equity ownership in a rapidly growing advanced energy company
Comprehensive medical benefits
Unlimited PTO
Free daily lunch and dinner provided onsite
Generous PPE stipend
High-impact startup environment with significant ownership and autonomy
Opportunities for rapid career growth and internal advancement
Direct collaboration with experienced operators, engineers, and industry leaders
The opportunity to help build and scale transformative energy technology from the ground up