Design of record · targets held to an honest ceiling

Specification & engineering drawings.

The HELIX module and core at design-of-record fidelity. Every value is computed, not measured in the field. Dimensions on the drawings are representative of the current design basis and will be superseded by qualified design documents.

Figure 1 · Module elevation, not to scale · design targets

Figure 2 · Core cross-section, control drums, fuel channels, diverse rod

Specification sheet

Module output	4.40 MWe at the cycle (11.0 MWth, 40% net dry sCO₂). Delivered at the meter is lower and site-specific once dry-cooler fans, house load and ambient derate are taken off; the configurator computes it per site
Site output	Number-up, 1 to 20+ identical modules; roughly 4–100 MWe (design target)
Configuration	Identical factory-sealed modules with N+1 reserve per site
Package	1.80 m core; 2.70 m pressure-boundary OD (casing stack not yet fixed)
Heat transport	421 sealed sodium heat pipes; no pumps (EM-pumped pool evaluated, not selected)
Fuel	UCO-TRISO, 19.75 wt% HALEU, graphite-moderated; inside the NRC-accepted EPRI-AR-1(NP)-A particle envelope
Heat-pipe wick	Composite: 14.7 µm surface pore, 48 arteries; 1.52× margin on peak duty (entrainment-limited)
Reflector	BeO, 0.40 m radial
Control	16 B4C control drums + 1 diverse shutdown rod
Reactivity feedback	−6 to −8 pcm/K (screening)
Core life	6.67 full-power yr at the current design point; bounded 6.67–6.91 pending the energy-per-fission normalisation (screening; unqualified)
Cooling	Fully dry, forced-draft dry coolers; zero cooling water
Power conversion	Dry sCO₂ Brayton, air-cooled, on skids outside the sealed module
Thermal storage	Molten-nitrate-salt buffer (peak-shave + trip bridge)
Safety I&C	FPGA deterministic (NRC-approved platform lineage)
Attestation	Non-safety, observe-only, behind a hardware one-way path
Transport	Factory-sealed. Outbound at 2.70 m OD is oversize and permittable. Road-legal is 2.60 m and costs core life. Whether a unit travels on ordinary roads or needs superload permitting is an open question, and the shield architecture inside the envelope is not yet fixed
Core return	Ship the irradiated core, not the module, in a Type B cask. Estimated 72 t, a superload. No certified cask is presently dimensioned for a 1.80 m core

All values are pre-QAPD screening resulargets. Heat transport is sealed sodium heat pipes; an EM-pumped sodium pool was evaluated and not selected. Physics figures are unqualified screening, pre-QAPD.

Every question, answered directly.

The questions a regulator, a partner, or an engineer asks about HELIX, answered by the founder. No forms, no sales pitch.

Jamie KlonczFounder · RankShield Energy

ONLINE

Pick a question on the left, or search above, and you'll get the direct answer, the way an answer engine would give it.

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What exactly is RankShield Energy building?

We are developing HELIX, our own sealed, transportable microreactor, targeting the NRC's proposed 10 CFR Part 57 microreactor framework with Part 53 as the backup pathway, with a qualified third-party fabricator manufacturing to our specification. What makes us different is not the reactor. It is that ours can be independently verified. Every module signs its telemetry and is attested from the factory floor to every operating hour.

Is this an operating reactor?

Not yet. It is pre-application development, not an operating product. No microreactor of this class has been built or run at its rated life yet, including ours. Every figure we publish is a design target and every physics result is unqualified screening, pre-QAPD. We label all of it honestly. That discipline is what makes the rest credible.

Why should a regulator or partner take a pre-application program seriously?

Because pre-application is exactly where the credible advanced-reactor cohort is. Part 53 only became final in 2026, the microreactor-specific Part 57 is still a proposed rule, and the leading microreactor developers are all in pre-application or early licensing. We treat the honest labels as milestones on a defined path we are actively executing, not as caveats.

How does HELIX make power without water?

Heat leaves the core through sealed sodium heat pipes, no pumps of any kind and no water anywhere in the primary. A dry supercritical-CO2 Brayton cycle on skids outside the sealed module converts it to electricity, targeting roughly 40 percent net. All heat is rejected to dry coolers, so there is no cooling tower and no water draw against the community that hosts the plant.

What fuel does it use, and can you actually buy it?

UCO-TRISO at 19.75 percent HALEU in a graphite core. It is the only advanced fuel form that is both NRC-precedented and purchasable from multiple US fabricators today. Our screening also shows the core reaches its reactivity limit with most of its uranium unburned, over 90 percent of the U-235 remains, so factory recharge re-banks that reactivity rather than discarding a nearly full fuel load.

How big is a site and how often do you swap the core?

A site numbers up identical sealed modules of roughly 5 megawatts each, one for a hotel or campus, twenty-plus for a hyperscale site. Staggered sealed-core swaps land on a roughly 5 to 7 year cadence and an N+1 reserve module carries an outage, so the modules are multi-year but the site runs indefinitely on rolling factory recharge. Our depletion screening puts module life at roughly four to five full-power years as modeled, likely five to seven once known model conservatisms are removed.

What happens in a total loss of power and cooling?

Nothing that matters. Reactivity self-limits on a strongly negative temperature coefficient, the control drums insert fail-safe by spring and gravity with no power needed, and decay heat leaves by natural-draft air cooling and radiation alone. A total loss of power and cooling is an availability event, not a safety event. There are no pumps anywhere in the reactor, so there is no loss-of-flow accident class, and the safety case never credits a pump, a valve, an operator, or a network.

Can the verification network ever interfere with safety?

No, by construction of the wiring. The attestation layer is classified non-safety and observe-only. It sits behind a hardware one-way path, so it can prove a module is intact but it physically cannot send a command toward a safety system. The safety systems are local and passive and unreachable from any network.

What does "verifiable" actually mean here?

Each module signs its sensor readings and firmware with post-quantum cryptography and anchors them to an append-only log co-signed by independent off-site witnesses. An operator, an insurer, or a regulator can check a module directly rather than take our word for it. Anyone can write the word secure. Only a verifiable reactor lets you check.

How does a fleet catch a problem before it becomes one?

Each site normalizes its performance against its own environment, then the RankShield Network compares every reactor to what its conditions predict. A reactor that drifts from that expectation stands out against an independent-witness fleet. The elegant part is that the same signal flags both wear and tampering, so one detector serves efficiency and security.

What is the licensing pathway?

Our primary target is 10 CFR Part 57, the NRC's proposed microreactor framework (proposed May 1, 2026; final rule expected November 23, 2026). It provides fleet approvals of identical reactors and is aimed at simple machines with simple safety systems, which the pumpless walk-away design is built to fit. Part 53, final since April 2026, remains the backup pathway and our scoping work against it transfers. We claim no approval, and no application is underway.

What still has to happen before you build hardware?

A stood-up NQA-1 quality program, independent physics validation with independent codes and ultimately test data, an NRC license, under Part 57 once the rule is final or under Part 53 as the backup, and validated demand. All of it is defined and stated on our licensing page. We make no economic, schedule, or performance guarantee, only honest labeled progress.