For years, advanced nuclear has lived mostly in the future tense. New reactor designs were coming. Factory-built reactors were coming. Microreactors for defense sites, remote industry, mining operations, and data centers were coming.

What the industry lacked was a visible sequence of physical milestones showing that these designs could move from presentation decks into hardware. That is why the recent wave of microreactors achieving criticality matters.

Criticality is not commercial operation. It does not mean a reactor is connected to the grid, earning revenue, or ready to be replicated at scale. But it does mean the reactor has sustained a controlled nuclear chain reaction. In plain English, the core is behaving like a real reactor, not just a modeled one.

From Isolated Milestones to an Industry Pattern

With Aalo Atomics now joining Antares Nuclear, Valar Atomics, and Deployable Energy in reaching criticality [1], the industry has moved from isolated proof points into something closer to a pattern.

These projects do not erase nuclear’s long history of delays or prove that microreactors are ready for commercial deployment. But they do show that, when the objective is focused and the regulatory pathway is aligned, nuclear hardware can move through design, fabrication, authorization, fuel loading, and startup on meaningful timelines.

For a sector often criticized as slow, expensive, and permanently stuck in the planning phase, multiple reactors reaching criticality marks a significant turning point.

The Investment Story Is Not Just the Startup

For investors, the most important takeaway may not be which microreactor startup “wins.”

Many of these developers remain private, early-stage, and technically risky. Some may struggle with licensing, financing, or the transition from first criticality to repeatable commercial deployment. The clearer investment signal is that these projects are already pulling established nuclear suppliers into real work.

That is where the story becomes relevant for the Range Nuclear Renaissance ETF (NUKZ). The fund aims to offer exposure not only to reactor developers, but also to the fuel, components, engineering, and services companies that make reactor deployment possible.

In other words, the microreactor milestones are not only about the companies whose names are on the reactor designs. They are also about the companies standing behind them.

Antares and BWXT: Fuel as the Critical Path

Antares Nuclear is a useful example. Antares’ Mark-0 microreactor became the first reactor to reach criticality under the Department of Energy’s Reactor Pilot Program. But the milestone was not achieved by the reactor developer alone.

While announcing that the company had successfully achieved criticality, the company's CEO, Jordan Bramble, provided insight [2] as to what enabled them to move as quickly as they did:

“BWXT fabricated our TRISO fuel. I believe that one of the reasons we moved so fast is because we leveraged a fuel specification developed and capitalized under [BWXT’s] Project Pele with decades of underlying qualification work performed and funded by the DOE.”

BWX Technologies (BWXT) (a NUKZ holding as of 7/8/26) supplied the advanced Tri-Structural Isotropic (TRISO) fuel that powered the test [3]. BWXT also processed the feedstock material used in that fuel.

That distinction matters because advanced reactors are often discussed as software-like innovations: smaller, modular, faster, more repeatable. In practice, they still depend on highly specialized physical supply chains.

TRISO fuel is a good example of that reality. It consists of tiny uranium fuel particles wrapped in multiple protective layers designed to retain fission products under extreme conditions. For many advanced reactors, especially high-temperature and microreactor designs, fuel is not an interchangeable commodity. It is part of the safety case, the performance case, and the deployment schedule.

If developers cannot get qualified fuel on time, their reactors do not go critical on time.

We believe that makes companies such as BWXT important beyond a single demonstration. BWXT is not just a supplier attached to one early milestone. It represents the type of nuclear-qualified manufacturing and fuel capability that advanced reactor companies will need if the sector is going to move from one-off tests to repeated deployments.

Aalo and Flowserve: The Component Story

Aalo Atomics provides a second example from a different part of the supply chain.

Aalo’s reactor design uses liquid sodium, which offers strong heat-transfer performance but also creates a demanding engineering environment. Sodium-cooled systems need equipment that can handle high temperatures, chemical reactivity, and precise flow control. That makes pumps, valves, seals, and related components more than ordinary industrial hardware.

Aalo’s partnership with Flowserve (FLS) (a NUKZ holding as of 7/8/26) is not simply a vendor relationship for off-the-shelf equipment [4]. It is a way to bring established component and flow-control expertise into a new reactor platform, particularly around the controlled movement of sodium through the system.

This matters because the nuclear supply chain is not only about uranium, enrichment, and fuel fabrication. Those areas are essential, but they are not the whole story. Reactors also need qualified valves, pumps, heat exchangers, forgings, instrumentation, controls, and maintenance support. 

A reactor developer can have a clever core design and still be constrained by whether the right components can be engineered, qualified, manufactured, and delivered at scale. That is the picks-and-shovels story inside advanced nuclear.

Why This Matters for Energy Investment Allocations

For investors considering using NUKZ to balance energy exposure, this is the part of the microreactor story that may matter most.

The recent criticality milestones do not need to be viewed as a direct bet on one microreactor startup over another. Instead, they can be understood as early evidence of increased activity across the nuclear industrial base. If more designs move from drawings to criticality, and eventually from criticality to commercial demonstrations, the demand signal likely broadens.

Fuel suppliers may benefit. Component manufacturers may benefit. Engineering firms may benefit. Nuclear services companies may benefit. Companies with qualified manufacturing capacity can become more valuable because qualification itself is a barrier to entry.

That is why diversified nuclear exposure may make sense. NUKZ aims to capture the companies that potentially benefit from activity across the nuclear ecosystem, including fuel fabrication, uranium processing, reactor components, engineering, and industrial equipment.

Holdings subject to change. To view holdings, click here. >>

Sources:
 
1. U.S. Department of Energy. 2026. "Department of Energy Celebrates Fourth Criticality Ahead of July 4th Goal." Energy.gov, July 6, 2026.
2. Bramble, Jordan (@jordanbramble). 2026. "Antares Mark-0 has achieved initial criticality." X, June 4, 2026.
3. Webb, Weston. 2026. "BWXT Manufactures TRISO Fuel Enabling First New Reactor Criticality Under DOE Program." BWXT, June 4, 2026. 
4. Arafat, Yasir. 2025. "Aalo Announces Strategic Partnership with Flowserve." Aalo Atomics, November 20, 2025.

Disclosures:
Investing involves risk, including possible loss of principal. There is no guarantee the Funds will achieve their stated investment objectives. Carefully consider the investment objectives, risks, charges, and expenses. This and other important information can be found in the Funds' prospectuses, which should be read carefully before investing and can be obtained by visiting www.rangeetfs.com/investor-materials, or by calling 1-800-617-0004.

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