The Anatomy of Nuclear Energy

Can the new kids on the block lead the charge towards energy superabundance?

Sanket & Sanjiv

“One uranium pellet - about the size of a fingertip - produces as much energy as 17,000 cubic feet of natural gas, 1,780 pounds of coal, or 149 gallons of oil - without the carbon.”

Lately, there has been a shift in how people talk about nuclear power. For the longest time, nuclear had this reputation of being dangerous, outdated, and politically messy, but now- it feels like we’re at the start of a quiet nuclear renaissance. A mix of climate urgency, energy insecurity, and some genuinely exciting tech is changing the narrative. Small modular reactors are getting real, fusion startups are raising serious money, and governments are suddenly way more open to nuclear as part of the clean energy mix. It’s not about going back to the old ways. It is about rethinking nuclear from the ground up. Let’s dig into what’s driving this shift and why it might stick this time.

For the longest time, nuclear power was stuck in this weird limbo. It was too risky for the mainstream, too slow for the VC world, and way too expensive to compete with solar and wind. But something’s shifted, and it’s not just a change in mood. The tech is finally catching up to the ambition. We're talking real progress in high-temperature superconductors, better magnets, faster simulations, laser systems, and even manufacturing techniques that actually make building reactors (especially fusion prototypes) easier and faster.

It’s not just about solving old problems either. The world’s energy needs are changing fast. You’ve got data centers popping up everywhere, space missions looking for compact power, the hydrogen economy heating up, and the whole AI ecosystem demanding clean, reliable energy at scale.

At the end of the day, energy isn’t just infrastructure. It is the foundation of civilization itself. The more of it we have, the more we can build, invent, automate, compute, and explore. Limit it, and you throttle progress. Cut it, and you risk collapse. There’s a deep, almost primal connection between energy and prosperity. Multiple studies have shown that a 1% bump in real GDP per capita can drive a 0.6% increase in total energy consumption. The relationship goes both ways.

Nuclear fits right into that future, especially the new-age stuff which are modular, agile, and safe by design. That’s why we’re suddenly seeing early-stage capital move in. And in India, we’re finally seeing founders who aren’t afraid to take on the beast that is nuclear. It feels like we’re standing right at the beginning of something big and this time, we’re not just watching it happen overseas.

Getting the basics right: Fission vs Fusion

Nuclear fission and fusion are two fundamentally different nuclear reactions that release vast amounts of energy but through opposite processes. Fission involves splitting a heavy atomic nucleus like uranium-235 or plutonium-239 into smaller fragments, releasing energy along with neutrons that can trigger a chain reaction. This process powers today's nuclear reactors and atomic bombs. Fusion, on the other hand, is the process that powers the sun. It involves merging two light nuclei, typically isotopes of hydrogen such as deuterium and tritium, into a heavier nucleus, releasing even more energy than fission. While fission technology is well-established, it generates a lot of radioactive waste and comes with meltdown risks. Fusion on the other hand, promises cleaner, safer, and virtually limitless energy, but is still in the experimental stage due to the extreme conditions required to sustain it.

Nuclear Fission: Advancing Modular and Micro-Reactors

A big part of the fission innovation happening today is in moving away from the massive, gigawatt-scale reactors that defined 20th-century nuclear power. We are seeing a shift toward smaller, more flexible designs that aim to be safer, faster to deploy, and more cost-effective. This includes Small Modular Reactors (SMRs), Advanced Modular Reactors (AMRs), and Microreactors each with their own take on rethinking nuclear. For example, SMRs typically generate less than 300 MWe of electrical output, while microreactors can generate as little as 20 MWe, making them great candidates for use in niche applications or remote areas.

The real charm of these smaller reactors is their modularity. By designing components that can be built in a factory and assembled on-site, we can streamline production, reduce construction times, and cut down on the costs that have historically plagued nuclear projects. Plus, many of these designs come with enhanced safety features that rely on natural physical processes like gravity or heat radiation to keep things cool, even in an emergency.

Startups are diving into all kinds of reactor types and coolant technologies, which is opening up the space in exciting ways. We’ve got companies working on smaller versions of tried-and-true Light Water Reactors (LWRs), which use standard uranium fuel and benefit from decades of operational experience. Then there are the High-Temperature Gas Reactors (HTGRs), which operate at super high temperatures (up to 1,000°C) and can be used for things like hydrogen production. Others are looking into Sodium-cooled Fast Reactors (SFRs) or Lead-cooled Fast Reactors (LFRs), which bring unique benefits but also some tricky handling challenges. Molten Salt Reactors (MSRs) are another interesting contender, using molten salts as coolant and enabling online refueling and fission product removal, which could improve fuel efficiency and reduce waste. And the Heat Pipe Reactors, mainly used in microreactors, where heat is transferred passively from the core using a sealed pipe system without the need for pumps or external power. a From tiny microreactors to big modular designs, there’s no shortage of innovation happening in the nuclear fission space.

Nuclear Fusion: The Race to Commercialisation

While fission is getting a 21st-century revamp, fusion still feels like the holy grail - endlessly promising and eternally “just around the corner.” But in the last few years, that corner is starting to look a lot closer, and startups are pouring in with fresh capital, bold claims, and some genuinely exciting breakthroughs.

At its core, fusion seeks to replicate the process powering the sun and stars by fusing light atomic nuclei typically isotopes of hydrogen like Deuterium (D) and Tritium (T) at extremely high temperatures (over 100 million degrees Celsius) and pressures. It’s clean, doesn’t create long-lived nuclear waste, and there’s no meltdown risk. But Fusion is incredibly hard to pull off on Earth. The fuel has to be heated and confined long enough to generate more energy from the fusion reaction than the energy used to start and maintain the reaction. Ignition is the point at which the reaction becomes self-sustaining and achieves a higher energy output than the energy input and is quantified as the net energy gain. That’s the milestone everyone’s chasing.

Most of the action today is in magnetic confinement fusion (MCF), where the idea is to hold the hot plasma in place using powerful magnetic fields so it doesn’t vaporize the reactor walls. Tokamaks are the most established version of this donut-shaped machines that use a combo of magnets and plasma current to twist the fuel into shape. They’ve got decades of R&D behind them (ITER being the big global example), but they’re prone to plasma instabilities, and scaling them up to a power plant hasn’t been straightforward. Commonwealth Fusion Systems (CFS) is betting big here with its high-field compact tokamak, while Tokamak Energy and Energy Singularity are going the spherical route to make things tighter and more efficient.

Then there’s the stellarator, which is a more elegant twist on the MCF. These machines skip the plasma current entirely and rely on complex magnetic coil geometry to keep the plasma stable. That makes them naturally disruption-resistant and great for steady-state operation. The problem used to be that designing those coil shapes which is incredibly complex. But with modern simulation tools and optimization algorithms, startups like Proxima Fusion, Type One Energy, Stellarex, and Renaissance Fusion are now making real progress.

Not everyone is following the tokamak-stellarator path. Some, like Zap Energy, are going minimalist with a Z-pinch approach using electric current alone to confine plasma, without using any external magnets. Others, like TAE Technologies, are taking a linear route using something called Field-Reversed Configuration (FRC), which they claim offers better scaling and simpler engineering.

In contrast to magnets, some startups are pursuing inertial confinement, by rapidly compressing tiny fuel pellets to trigger fusion before the pellet can blow itself apart. The laser-driven approach is the most well-known version of this and the National Ignition Facility in the US pulled it off in 2022 with a giant laser array. Startups like Marvel Fusion, Focused Energy, and Xcimer are now working on doing the same, but faster, cheaper, and more repeatably often equipped with liquid-wall chambers to handle the blast. There’s also a more kinetic twist called projectile fusion, where a hypervelocity slug is fired at a target First Light Fusion is the main player here.

And then there are the hybrid approaches, which try to combine the strengths of magnetic and inertial confinement. This bucket includes Magneto-Inertial Fusion (MIF), where you start with a magnetically confined plasma and then give it a sudden mechanical or electromagnetic squeeze. Helion Energy is a standout here, using colliding plasmas and aiming for direct energy conversion (no turbines, just straight electricity from the fusion reaction). General Fusion is going with pistons compressing a magnetized target inside a liquid metal sphere. NearStar Fusion, meanwhile, is literally railgunning plasma targets into each other. It's wild stuff.

One big unlock across many of these approaches has been high-temperature superconducting (HTS) magnets These materials let you build much stronger magnetic fields with smaller footprints, which makes compact reactors way more viable. HTS is basically what makes CFS, Tokamak Energy, Proxima, and Renaissance even possible. On top of that, improved computing power has made it way easier to simulate complex plasma behaviour and optimize coil designs, especially for machines like stellarators that were previously too chaotic to model accurately.

The fusion space is still high-risk, but the energy, diversity of ideas, and sheer volume of engineering talent rushing in right now is heating up the space. Whether it’s lasers, railguns, magnets, or spinning plasma donuts someone’s going to crack it. And when they do, it’s going to change everything.

Is Nuclear Waste Really a Concern?

Nuclear waste gets a lot of attention, but rarely in proportion to the facts. The entire U.S. commercial nuclear industry, powering millions of homes for over 60 years, has produced roughly 90,000 metric tons of used fuel, all of which could fit on a single football field stacked about 10 meters high. Compare that to the over 36 billion tons of CO₂ emitted globally every year from fossil fuels, waste we can’t see, touch, or contain. Nuclear waste is solid, doesn't escape into the environment, and is stored under strict regulation, often on-site in shielded dry casks or cooling pools designed to last for decades.

What's more, this waste still contains over 90% of its original energy, making it a resource, not just a byproduct. Fast reactors and reprocessing technologies can extract that energy, reducing both the volume and longevity of the waste dramatically. For example, next-gen reactors can reduce the hazardous lifespan of spent fuel from 100,000 years to just a few hundred. Unlike fossil fuel pollution, which is vast, diffuse, and ongoing, nuclear waste is small, contained, and decreasing in danger over time. It’s not a crisis, it’s a solvable engineering problem with proven answers and better ones on the way.

From Heavy Water to High Potential: A New Era for Indian Nuclear

India’s nuclear journey has always been one of quiet ambition. While most of the world remembers us for Pokhran and policy debates, the real story lies in the vision laid down by Homi Bhabha and the Three-Stage Nuclear Programme a bold, technically elegant roadmap built not around Western resources but around India’s own constraints and opportunities. This wasn’t just about energy; it was about self-reliance, long-term thinking, and strategic autonomy.

But for most of its history, the Indian nuclear sector has operated behind closed doors state-run, bureaucratically rigid, and largely off-limits to the kind of entrepreneurial energy that’s now reshaping every other frontier. That’s finally beginning to change.

We’re at an inflection point. Energy demand in India is skyrocketing. The path to decarbonization isn’t optional anymore it’s existential. And as we double down on solar, wind, and green hydrogen, there’s a growing realization that these alone won’t get us to net zero, or even to a stable grid. We need clean, baseload energy that doesn’t depend on whether the sun is shining or the wind is blowing. That’s where nuclear particularly next-generation nuclear starts to look not just viable, but inevitable.

And this time, it's not going to be led solely by the old guard. We’re seeing the first sparks of a startup-led nuclear wave. Small teams, emerging from research labs and universities, are starting to ask the right questions. What if we rethink nuclear from first principles? What if reactors were modular, manufactured like aerospace systems, not constructed like dams? What if we could build with timelines of 2-3 years, not 15? What if we could plug a 20 MW reactor into a data centre, or use high-temperature fission to decarbonise steel and ammonia?

Globally, that’s already happening; startups are shaping the future of nuclear in a way governments and legacy players simply can't. The US, Canada, and the UK have created regulatory sandboxes and dedicated capital pathways for fusion and small reactor experiments. Companies like Helion, CFS, Radiant, and NuScale have raised hundreds of millions and are now building physical systems.

India is still early to this, but the ingredients are there. We have deep technical talent: nuclear physicists, reactor engineers, control systems experts many of whom have either stagnated in public labs or left to build abroad. We have a growing pool of patient, deeptech capital and a hunger for strategic tech. What’s been missing is a framework that encourages entrepreneurial risk-taking in nuclear something that allows startups to iterate, experiment, and build outside the traditional mold.

There are already early experiments underway, the signs are encouraging, What we need now is acceleration in policy tailwinds, regulatory innovation, and a public narrative that’s not stuck in Cold War nostalgia.

There’s a play here for the right kind of founders those who are unfazed by complexity, comfortable at the intersection of physics and systems engineering, and hungry to build something with a 30-year relevance horizon. And there’s a play for investors too those who understand that the next energy supercycle won’t be won in silicon or solar panels alone, but in unlocking the clean, firm, infinitely scalable power source sitting right under our noses.

Nuclear isn’t just back it’s being reimagined, and India has every reason to lead that future. We are a nation of brilliant scientists, engineers, and entrepreneurs who’ve built reactors in remote corners, launched satellites on shoestring budgets, and powered a billion dreams with limited means. Our land holds one of the world’s largest reserves of thorium, a resource most countries can only dream of, and we’ve designed an entire nuclear roadmap around it. For a country that must power the aspirations of 1.4 billion people without choking its skies or compromising its sovereignty, nuclear isn’t just an option, it’s a responsibility. And when India leads, it doesn’t just catch up, it sets the standard.

Indian Startups leading the charge:

If you are curious about what the world would look like if nuclear helps us achieve Energy superabundance, read Benjamin Reinhardt’s Making Energy Too Cheap to Meter: https://worksinprogress.co/issue/making-energy-too-cheap-to-meter/

Thanks for Reading!

If you are a founder, Investor or an ecosystem enabler in Nuclear Energy, would love to chat, drop me a note at sanket.panda@bluehill.vc / sanket7panda@gmail.com