Thorium Atomics · The Tesseract TGR

Building the
second nuclear
era.

Factory-built reactors that deliver 750 °C heat and firm power, and breed part of their own fuel from thorium. More power from less uranium, for the industries and the century ahead.

250_MWthThermal output

~100_MWeElectrical output

750_°CCoolant outlet

<10_%Enrichment

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Where this goes

HeatHeat for the industries electricity cannot reach.750 °C, delivered where steel, cement, ammonia and hydrogen are made.

FuelFuel for centuries.Thorium is three to four times more abundant than uranium. The United States alone holds about 600,000 tonnes.

ScaleBuilt like a product.Made in factories and delivered by road, so the fleet gets faster and cheaper to build as it grows.

MedicineMedicine from the same fuel.The thorium cycle builds the parent of actinium-225, a scarce isotope for targeted cancer therapy.

Sheet 02 / 11Design intentScale NTS

The hard part of the energy problem is heat.

Roughly a quarter of global energy demand is industrial process heat, and most of it is burned rather than generated. Electrification handles the low end of that range well. Above about 400 °C the list of practical clean options gets very short, and above 700 °C it nearly disappears. That band is what this reactor was sized for. Industrial operators are being asked to decarbonize on timelines that assume a solution exists for that heat. For the hottest processes, it does not yet.

Table 02.1 · Industrial heat demand by temperature band
Band	Representative processes	Clean supply available today
< 150 °C	Space heat, drying, food	Heat pumps and resistive electrification work well here.
150–400 °C	Paper, chemicals, refining	Clean options exist. Cost and scale are uneven.
400–700 °C	Hydrogen, ammonia, glass	Very few credible clean options at industrial scale.
700 °C +	Cement, steel, high-temperature process	Almost nothing clean serves this band today.

02.1 · Duty

750 °C, delivered as heat or as power.

Helium leaves the core at 750 °C and returns at 250 °C. That outlet temperature is high enough to drive chemical process heat directly, and high enough for an efficient power conversion cycle when the customer wants electricity instead. One reactor design serves both, and the choice is made at the site rather than in the reactor.

Helium is chemically inert, remains single-phase under reactor operating conditions, and has low neutron-activation potential. It avoids the boiling, combustion and energetic chemical-reaction hazards associated with some other reactor coolants, which removes a category of accident from the design problem before analysis starts.

Sheet 03 / 11General arrangementScale NTS

Inside the vessel.

A helium-cooled pebble bed inside a forged, bolted pressure vessel: uranium driver fuel in the middle, a thorium blanket around it, graphite returning neutrons to the core, and reactivity control that does not depend on penetrating the fuel region. The detailed arrangement stays in the drawing office. These are the numbers that define the machine.

Table 03.1 · Reference design, principal parameters
01	Reactor class	High-temperature gas-cooled, pebble bed
02	Thermal output	250 MWth
03	Electrical output	~100 MWe
04	Coolant outlet / inlet	750 °C / 250 °C
05	Coolant	Helium. Inert, single-phase, chemically inactive
06	Fuel form	TRISO particles in graphite pebbles
07	Driver enrichment	Below 10 percent uranium-235
08	Core arrangement	Uranium driver bed with a thorium blanket
09	Mined uranium over life	Roughly half a comparable light-water reactor
10	Design life	60 years

Fig. 03.1 · Reactor pressure vessel, exterior. Rendered from the engineering model. Illustrative, not to scale.

Sheet 04 / 11Core and fuelScale NTS

The fuel is a sphere, and it never stops moving.

Instead of fuel assemblies fixed in place for years and replaced during an outage, the core is a slowly moving bed of graphite spheres. Pebbles are added at the top and withdrawn from the bottom while the reactor runs.

Fig. 04.1 · Fuel pebble, sectioned, with TRISO particle enlarged. Schematic.

04.1 · Containment at the particle

Every fuel kernel carries its own pressure vessel.

Each pebble holds thousands of TRISO particles: a fuel kernel less than a millimetre across, sealed in carbon layers and a silicon carbide shell that holds fission products in at temperatures far above normal operation. TRISO has been made and irradiated under U.S. Department of Energy programs for decades, so the fuel follows an established qualification path.

04.2 · Refuelling

Online refuelling, without a dedicated outage.

Pebbles leave the bottom of the bed, are checked, and either return to the top or retire, all while the reactor stays at power. Because fuel is replaced continuously, the core never needs a large excess of reactivity to last until the next outage.

04.3 · The thorium blanket

Neutrons that would have leaked out make fuel instead.

Thorium-bearing pebbles sit where neutrons would otherwise escape the core. Thorium-232 captures them and becomes uranium-233, which fissions, so the reactor makes part of its own fuel as it runs. It is a near-breeder, and we claim no more than that.

The design target is about 50 percent less lifetime mined uranium than a comparable light-water reactor of the same output. It is being confirmed on a full-core analysis that resolves every pebble, and will be checked independently with qualified codes.

That matters because demand is outrunning supply: the NEA and IAEA project annual uranium requirements rising from about 64,500 tonnes today to between 84,800 and 143,900 tonnes by 2050 (Uranium 2026). Thorium is three to four times more abundant than uranium, and much of it is already mined as a by-product of rare earth processing.

Sheet 05 / 11Isotope pathwayScale NTS

A second product, built into the physics.

Reactors that run thorium accumulate thorium-229 as a matter of physics. Thorium-229 is the parent of actinium-225, one of the scarcest and most sought-after isotopes in medicine. We did not design the reactor to make it. The reactor makes it anyway.

Why actinium-225 is hard to get.

Targeted alpha therapy attaches an alpha-emitting isotope to a molecule that binds to a cancer cell, delivering a dose over a range of a few cell diameters. Actinium-225 is the leading candidate for it. Global supply comes largely from a small inventory of legacy thorium-229 held at a handful of national laboratories, and that supply has been the constraint on clinical programs for years.

A reactor running a thorium cycle builds thorium-229 inventory as an ordinary consequence of operation. Recovering it is a fuel-cycle and separations problem rather than a reactor problem, and it is not on the critical path for the energy business.

We do not present this as the reason to build the reactor, and we do not put a number on it. Energy comes first. This is what sits underneath, as a consequence of the selected thorium-augmented fuel architecture.

Fig. 05.1 · Partial decay chain

Th-232Thorium-232Fertile. 14.05 billion year half-life.

U-233Uranium-233Bred in the blanket. This is the fuel.

Th-229Thorium-229Accumulates slowly. 7,340 year half-life.

Ra-225Radium-22514.9 days.

Ac-225Actinium-2259.9 days. The isotope in demand.

Sheet 06 / 11Safety basisScale NTS

Safety built into the physics.

The Tesseract TGR holds itself in balance through the physical properties of its fuel, graphite and helium. It is designed to remove its own heat without pumps, power or operator action, and every fuel particle keeps its fission products sealed in.

06.1

Self-regulating

As the fuel warms, the reaction slows by itself. The fuel and graphite provide this balance directly, with no power, signals or operator needed.

06.2

Low power density, large heat capacity

The core spreads 250 MWth across a large graphite mass. Graphite holds a great deal of heat and gives it up slowly, so the core takes hours to change temperature rather than seconds.

06.3

Decay heat leaves by conduction and radiation

The vessel is slender enough that residual heat can reach the surrounding structure by conduction and radiation. The design objective is to remove decay heat without relying on powered pumps or immediate operator intervention. This performance remains subject to qualified thermal-hydraulic and safety analysis.

06.4

An inert, single-phase coolant

Helium is chemically inert, remains single-phase under reactor operating conditions, and has low neutron-activation potential. It avoids the boiling, combustion and energetic chemical-reaction hazards associated with some other reactor coolants. Losing coolant pressure is a loss of cooling, not the start of a chemical event.

06.5

Control from outside the fuel

The control rod channels sit in the reflector rather than in the fuel region, so reactivity control does not depend on penetrating the moving bed.

06.6

Containment at the particle

The silicon carbide shell around each fuel kernel retains fission products well above the temperatures the reactor reaches, including in every event the design is analyzed against.

Sheet 07 / 11Application and sitingScale NTS

Built for customers whose energy problem is not solved by more grid.

A compact, self-contained unit that can sit inside an industrial fence line, next to a data center campus, or in a utility corridor. The reactor does not change between these cases. What changes is whether the output is taken as heat or as electricity.

Fig. 07.1 · Industrial Heat · Schematic

Process heat for heavy industry

750°C helium delivered directly to steel, cement, ammonia, hydrogen, and chemical production. Co-located with industrial facilities under long-term take-or-pay heat offtake agreements.

Temp range: 400–750°C
Offtake: Heat & steam
Siting: Inside fence-line
Counterparty: Industrial operator

Fig. 07.2 · Data Centers · Schematic

Firm power for AI and compute

Behind-the-meter clean electricity for campuses where uptime, energy density, and carbon commitments are non-negotiable. Designed to reduce exposure to transmission constraints and to intermittency.

Output: ~90–100 MWe
Offtake: Firm electricity
Siting: Campus-adjacent
Availability: >95% target

Fig. 07.3 · Utilities and Repowering · Schematic

Repowering coal sites for utilities

Retiring coal plants already have the grid connection, water, cooling and a trained workforce. The reactor takes the place of the boiler and the plant keeps its switchyard and its people.

Output: ~90–100 MWe
Siting: Existing plant site
Grid: Existing interconnect
Counterparty: Utility or co-op

Fig. 07.4 · Strategic · Schematic

Energy security infrastructure

Resilient power and heat for critical facilities, defense installations, and strategic supply chains where fuel independence and long-duration reliability matter most.

Posture: Resilient
Fuel: Multi-year
Grid: Islanded-capable
Offtake: Long-horizon

Sheet 08 / 11Development methodScale NTS

Iterate in software. Commit in steel once.

Reactor programs are slow largely because every design change is expensive to evaluate. We build and analyse the reactor in software first, so that trade-offs surface early, the reasoning is preserved, and the engineering record is assembled as the design is made rather than reconstructed afterwards.

08.1

Settle it by running it

Core geometry, fuel loading, enrichment and the blanket configuration were each decided by analysing the alternatives rather than by argument. The sensitivity of the design to each choice is on record, which is what lets us say plainly which parameters are locked and which are still open.

08.2

Every number has a calculation behind it

Each figure in the design basis traces to a specific analysis with recorded inputs, code version and date. A regulator and an engineering contractor both need that provenance, and it is far cheaper to keep from the beginning than to reconstruct at the end.

08.3

The drawings come from the design data

Drawings and the design basis are generated from the same source as the analysis, so the engineering record and the design cannot quietly drift apart as the work advances.

08.4

Qualified codes carry the safety case

Our own tools inform the design. The structural, thermal-hydraulic, seismic and fuel-performance analyses that support a license application are performed in established qualified codes, by organisations with the quality programs to stand behind them.

Sheet 09 / 11Revision historyScale NTS

Where it stands.

From independent concept review to an NRC pre-application, national-laboratory agreements and a constructor review in six months. Newest first; each entry carries its reference.

Revision history
Rev	Date	Description	Ref
M	2026 · 09	Evaluated benchmark handbooks approved The OECD Nuclear Energy Agency approved our access to its evaluated criticality and reactor-physics benchmark handbooks, which extend our code checks to further pebble-bed and thorium experiments.	OECD NEA
L	2026 · 09	Registered for U.S. federal work SAM.gov registration active and a CAGE code assigned to the Oak Ridge operation, the prerequisite for Department of Energy vouchers and federal contracts.	SAM.gov
K	2026 · 09	Oak Ridge office established A Tennessee office in Oak Ridge, alongside Toronto, close to Oak Ridge National Laboratory and the U.S. nuclear supply chain.	Oak Ridge, TN
J	2026 · 09	Constructability review package issued to a nuclear constructor Under a mutual confidentiality agreement with a major North American nuclear constructor, a 33-page constructability review package was issued for engineering review: the reactor island drawing set of thirteen sheets, the design basis with its open-items register, and the fabrication, transport, erection and fuel-handling arrangements, sized against road and rail delivery envelopes. A technical workshop against the package is the next step.	33 pages
I	2026 · 08	National-laboratory code licence executed A software licence agreement with Idaho National Laboratory covering the federal fuel-performance and multiphysics analysis codes used in advanced-reactor licensing. Our own tools inform the design; qualified codes carry the safety case.	Code licence
H	2026 · 07	Independent verification and demonstration siting in progress A Strategic Partnership Project agreement with Idaho National Laboratory is in Department of Energy review; the first task cross-checks our reactor physics results in MCNP and Serpent.	INL

Earlier entries, 2026.03 to 2026.07 ↓

Revision history
Rev	Date	Description	Ref
G	2026 · 07	Design basis and preliminary drawing set issued A documented design basis for the reactor island and module systems, issued together with an open-items register that states plainly what has not yet been analyzed. Constructability and road transport of the major components were assessed against real delivery constraints rather than assumed.	TAI-DBD-001
F	2026 · 07	NRC project number assigned The NRC assigned project number 99902174 and a project manager in the Office of Advanced Reactors. A project number is an administrative and billing reference for pre-application engagement. It is not a license application, and it carries no NRC approval or endorsement of the design. A regulatory engagement plan is in preparation.	No. 99902174
E	2026 · 06	Operating-reactor benchmarks reproduced The HTR-10 and HTR-PM first-criticality benchmarks, from the two operating Chinese pebble-bed reactors, reproduced in our design platform: seven measured quantities, with the temperature coefficients carried as open items. Reproduction on the same code stack we use for the Tesseract; it is not a qualification of the design.	HTR-10 · HTR-PM
D	2026 · 06	Pre-application engagement opened with the U.S. Nuclear Regulatory Commission Notice of intent submitted 23 June 2026 under 10 CFR Part 53, the NRC's technology-inclusive framework for advanced reactors. The Canadian pathway, a CNSC Vendor Design Review, is maintained in parallel.	10 CFR Part 53
C	2026 · 05	Reference configuration selected 250 MWth, LEU+ TRISO driver fuel below 10 percent enrichment with a thorium blanket. Supported by a multi-cycle depletion analysis run across the full fuel cycle.	250 MWth
B	2026 · 03	United States provisional patent application filed Covering the reactor architecture. Patent pending. Further applications are in preparation with counsel.	Patent pending
A	2026 · 03	Independent review of the concept Dr. Ayman Hawari of Texas A&M University reviewed the December 2025 concept whitepaper as an independent consultant. He assessed the concept as a technically plausible high-temperature gas-cooled reactor optimized for improved thorium utilization, found the overall architecture consistent with known strategies for achieving the targeted performance, and set out five areas requiring quantitative analysis to confirm it. That analysis is the work that has followed. The reference configuration has since been revised and has not been through a further external review.	External review

General note

During my life I have witnessed extraordinary feats of human ingenuity. I believe that this struggling ingenuity will be equal to the task of creating the Second Nuclear Era. My only regret is that I will not be here to witness its success.

Alvin Weinberg
Director, Oak Ridge National Laboratory, 1955 to 1973

The second nuclear era Weinberg described is not abstract. It begins with decisions made now, by people with the physics and the industrial will to build.

Alvin Weinberg looking through the control room window of the Molten-Salt Reactor Experiment at Oak Ridge National Laboratory, with 6000 full power hours written on the glass. — Alvin Weinberg at the MSRE, Oak Ridge National Laboratory. In 1968 the MSRE became the first reactor to run on uranium-233, the fuel the Tesseract breeds.Photograph: Oak Ridge National Laboratory, U.S. Department of Energy.

Sheet 10 / 11OrganizationScale NTS

People who have run reactors, licensed them, and built them.

Between them the team has led nuclear engineering at Ontario Power Generation, run the Tennessee Valley Authority, licensed new build for the Canadian regulator, and worked the thorium fuel cycle at Oak Ridge.

Young Hwang

Co-Founder & Chief Executive OfficerEx-RBC and CIBC institutional markets

Co-architected the Tesseract simulation platform and helped originate the company's strategic direction. Leads federal engagement and long-term platform positioning. Over two decades prior in institutional markets, including senior roles at RBC Capital Markets and CIBC World Markets. Co-founded the company around a simple conviction: the future of nuclear will belong to platforms that solve for industrial heat, fuel resilience, and energy sovereignty, not electricity alone.

David Kerr

Co-Founder & ChairmanFounder, Algonquin Power

Founder of Algonquin Power and a veteran builder of public-market energy platforms, he helped scale the company from its initial listing into a multi-billion-dollar infrastructure enterprise. Decades of experience in board governance, capital formation, strategic transactions, and long-horizon company building across regulated power markets and energy infrastructure.

Jeff Lyash

Senior AdvisorFormer CEO, TVA and OPG

Four decades of nuclear and power industry experience. Former President and CEO of the Tennessee Valley Authority and of Ontario Power Generation, two of North America's largest nuclear-powered utilities. Prior senior leadership at Duke Energy, Progress Energy, and Chicago Bridge & Iron Power, and senior technical and management roles at the U.S. Nuclear Regulatory Commission. Currently on the Board of Directors for Dominion Energy and Aecon Group.

Dr. Jack Vecchiarelli

Chief Scientific & Regulatory OfficerFormer VP Nuclear Regulatory Affairs, OPG

Over 30 years of leadership in nuclear safety and licensing from Ontario Power Generation (OPG) and Atomic Energy of Canada Ltd. (AECL), including as VP of Nuclear Regulatory Affairs at OPG. Spearheaded licensing efforts spanning license renewals for operating plants and site preparation / construction licensing for new builds. Canada's representative at IAEA member state meetings on nuclear safety. Ph.D. Mechanical Engineering, University of Toronto.

Craig Sellers

Head of EngineeringFormer Chief Nuclear Engineer, OPG

Former Chief Nuclear Engineer and VP, Engineering and Modifications at Ontario Power Generation. Led nuclear engineering, major modification programs, and new-build technical strategy across one of North America's most demanding fleet environments. Deep experience in reactor design, core physics, refurbishment, life extension, and modernization of critical nuclear systems.

Loong Yong

Board DirectorFounder, Spectra Tech; U-233 work at ORNL

Founder and President of Spectra Tech Inc., a nuclear services firm based in Oak Ridge, TN with ~350 employees across multiple DOE sites and national laboratories. Ph.D. Nuclear Engineering, University of Tennessee, under Dr. Bernard Spinrad (inventor of the Molten Salt Reactor Experiment). Direct thorium fuel cycle experience, including five years at ORNL Building 3019 (the U-233 repository), and Fort St. Vrain spent-fuel management for DOE since 2016.

Michael Cho

Co-Architect, Tesseract PlatformBuilt the Mjolnir design platform

Soo-Whan Kim

Chief Financial Officer15+ years of public-company finance

Paul Hardy

Co-Founder & DirectorFormer MD, Desjardins Securities

Prit Singh

Board DirectorFounder, Thesis Capital

Technical advisers

Dr. Kenneth Ricci

Reactor Physics Advisor

PhD Physics, Stanford. Thorium breeder modeling and Monte Carlo neutronics. Published in Nuclear Technology. Fusion neutron source development at Adelphi Technology.

Dr. Tarak Woddi

Reactor Physics Advisor

PhD Nuclear Engineering, Texas A&M. Licensed CANDU reactor operator. Thorium breeder reactor design and fuel cycle modeling. PRA across 11 nuclear power plants.

Mark Hoffman

Nuclear Safety Advisor

Westinghouse safety advisor for AP1000. Senior Reactor Operator, Braidwood & AP1000. 19 years at Exelon; thermal-hydraulics and accident analysis.

Sheet 11 / 11ContactScale NTS

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Building thesecond nuclearera.

750 °C, delivered as heat or as power.

Every fuel kernel carries its own pressure vessel.

Online refuelling, without a dedicated outage.

Neutrons that would have leaked out make fuel instead.

Why actinium-225 is hard to get.

Self-regulating

Low power density, large heat capacity

Decay heat leaves by conduction and radiation

An inert, single-phase coolant

Control from outside the fuel

Containment at the particle

Process heat for heavy industry

Firm power for AI and compute

Repowering coal sites for utilities

Energy security infrastructure

Settle it by running it

Every number has a calculation behind it

The drawings come from the design data

Qualified codes carry the safety case

Evaluated benchmark handbooks approved

Registered for U.S. federal work

Oak Ridge office established

Constructability review package issued to a nuclear constructor

National-laboratory code licence executed

Independent verification and demonstration siting in progress

Design basis and preliminary drawing set issued

NRC project number assigned

Operating-reactor benchmarks reproduced

Pre-application engagement opened with the U.S. Nuclear Regulatory Commission

Reference configuration selected

United States provisional patent application filed

Independent review of the concept