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About Polyenergetics


Climate change is a global challenge affecting every human and every ecosystem. Solving it requires clean, scalable, and deeply reliable energy systems. Nuclear fission is one of the world’s most powerful pathways to deep decarbonization, but it has its own challenges of safety, timelines and cost of deployment.


At PolyEnergetics, we are building a micro-modular reactor (MMR) based on the Molten-Salt Reactor (MSR) concept, to address these challenges head-on and still provide clean, safe, reliable energy for all, economically and at scale.. We leverage AI, high-performance compute and advanced manufacturing techniques to achieve this.


Passionate about driving progress without harming the planet?

Join us!


As an early member of the team in this exciting field of nuclear engineering, you get to play an outsized role in making a positive impact on the world we live, working alongside the founding team.

About the role


We're looking for a Reactor Physicist to own the neutronics heart of a next-generation molten-salt reactor. This is not incremental work on a mature design — it's foundational physics for a machine that doesn't exist yet, built on a modern, open, compute-first stack. You'll take models from first principles to regulator-ready substantiation, and see your analysis directly shape a reactor being brought to life.


What you’ll do

  • Develop and validate reactor physics models and simulations across steady-state, transient, and design-basis accident conditions.
  • Couple nuclear physics simulations to CFD to accurately capture core performance in a flowing-fuel molten-salt environment.
  • Perform and/or supervise finite-reactor-core, kinetics, advanced-fuel-cycle, and Monte Carlo calculations.
  • Prepare inputs and run reactor physics codes; develop, adapt, and modify those codes to implement new methods or new types of calculations as the design demands.
  • Develop methodologies and perform reactor physics analyses that directly support design and commercial activities.
  • Build relationships with industry and academic experts to bring the best existing knowledge into our models, simulations, and wider R&D.
  • Present and substantiate nuclear physics to regulatory bodies and other stakeholders.
  • Document analyses in technical notes and reports, and present results clearly at meetings.
  • Develop analysis basis plans, propose approaches for reactor physics tasks, and estimate, monitor, and schedule work to hit completion dates.
  • Adapt fast — take on varied assignments and respond quickly as project needs evolve.


Required experience

  • PhD in Nuclear Engineering / Reactor Physics or a closely related field — or a Master's with equivalent hands-on analytical experience.
  • Demonstrated experience in reactor physics and criticality safety analysis.
  • Hands-on proficiency with at least one neutron transport suite — SCALE/KENO, MCNP, Serpent, or a deterministic code such as WIMS. Our internal stack leans toward open-source tools like OpenMC, MOOSE, Moltres, and OpenFOAM for Nuclear, so familiarity with (or excitement to work in) that ecosystem is a real plus.
  • Familiarity with Deterministic finite-difference / finite-volume (diffusion or transport) like DIF3D, PARCS
  • Strong scientific programming skills in one or more of Python, MATLAB, C/C++, or C#.
  • Experience producing regulator-facing documentation and working to formal QA/licensing standards.
  • Ability to work within multidisciplinary teams (thermal, structural, safety) and to communicate technical results clearly to non-specialists.
  • Comfort across computing environments; proficiency in both Linux and Windows is a strong asset.


What we value in you

  • Ownership. You will not be handed a spec and a deadline. You will figure out what needs simulating, go do it, and come back and tell us what it means. Early-stage means the gaps are yours to find.
  • Intellectual honesty. Anyone can produce a colourful contour plot. We want the engineer who says this is where my model is weak, and here's how I'd validate it — because in nuclear, that instinct is not pedantry, it's the whole discipline.
  • Rigour without ritual. We respect the standards and follow the procedures. We also question anything we're doing purely because it has always been done that way.
  • Motivation that doesn't need managing. This is a startup building a nuclear reactor. That is exactly as demanding as it sounds, and the people who thrive here are the ones who find that thrilling rather than daunting.


Why this role is different

  • Most reactor physics jobs hand you a settled design and a decades-old code you're not allowed to touch. This one doesn't.
  • Here, the design is still being written — and your physics helps write it. You'll work on a molten-salt MMR where the fuel moves, the neutronics and thermal-hydraulics are inseparable, and the coupled behaviour is genuinely at the edge of the field. You'll build on a modern, open-source, compute-first stack rather than fighting proprietary black boxes, and you'll have AI, HPC, and advanced manufacturing as real tools at your disposal, not slideware.
  • You'll join early, alongside the founding team, with the kind of scope and ownership that simply doesn't exist at a large, established organisation — the freedom to propose approaches, shape methodologies, and stand up the analysis basis for a reactor from the ground up. And the reason all of it matters: the work goes toward clean, safe, reliable energy for everyone, and a real dent in climate change.
  • If you want your neutronics to move something in the world — this is the room to be in.


How to Apply:

Just send us an email at info@polyenergetics.com, with a note about yourself and your resume. We’ll be in touch!


Work Location - Mumbai

Work Mode - Office