Small Modular Reactor Patents: Who Leads, Where the Gaps Are 2026
- Filing already peaked. 2020 was the high point at 9 filings; by the 2022 midpoint activity had fallen back to 2, and the trend has not recovered since.
- No single assignee is filing every year. Every tracked assignee shows zero filings in the latest year, which points to a field where continuation activity has stalled rather than a runaway leader pulling ahead.
- Claims cluster tightly around G21C. 32 of 33 records sit in the nuclear reactor subclass, with only scattered overlap into power-plant systems, medicinal preparations and business-process filings.
What this landscape covers
This landscape tracks 33 patent families published between 2015 and mid-2026 that combine small modular reactor terminology with passive safety, integral pressure vessel, load following, factory fabrication or core design language, filtered to the G21C, G21D and G21D3 classification codes. It is a narrow, claims-focused slice of the broader nuclear patent corpus, built to surface who has staked out the mechanical and systems-level claims rather than the wider reactor-physics literature.
Filing activity is small in absolute terms and concentrated in a handful of years, which makes this a field where a single well-drafted family can still shift the competitive picture. Publication lags filing by roughly 18 months, so the apparent drop-off in the most recent years understates real filing activity that has not yet published.
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Filing trend and classification mix
Two views of the same 33 families: how filings moved year over year, and where they sit across the IPC scheme.
Filings rose to a 2020 peak, then fell back
Filings moved from 3 in 2017 to a peak of 9 in 2020, then dropped to 2 by the 2022 midpoint and have not recovered to peak levels since. Treat the final one or two years as incomplete rather than as a genuine decline, given normal publication lag.
Nuclear reactor claims dominate the mix
32 of the 33 records fall under G21C (nuclear reactors), with a much smaller cluster of 5 in G21D (nuclear power plants) and single incidental hits in medicinal preparations and business-process classifications — likely artefacts of cross-filed applications rather than a genuine adjacent branch.
Shares are the percentage of the 33 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Small Modular Reactor Technology with Eureka
This page is one run against one query. Ask Eureka your own question about small modular reactor technology and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited families in this set
Small modular reactor power plant with load following and cogeneration capabilities and methods of using (US20190206580A1)
Provided herein is a small modular nuclear reactor plant that can comprise a reactor core comprising a primary sodium comprising cool primary sodium flow and heated primary sodium flow. Heated primary sodium flow can enter one or more IHXs where heated primary sodium exchanges heat with secondary sodium flowing through at least one intermediate sodium loop. Intermediate sodium loop can comprise secondary sodium flow that can transport heat to energy conversion portion via a heat exchanger. Energy conversion portion can comprise a bypass valve. Bypass valve can bypass an energy conversion working fluid (such as S-CO2) away from a turbine during periods of adjustment as discussed herein.Filed by Advanced Reactor Concepts LLC, published 2019-07-04.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20180277260A1 | Optimized nuclear fuel core design for a small modular | 25 |
| 2 | US20160329113A1 | SLIMM-Scalable Liquid Metal Cooled Small Modular Reactor | 25 |
| 3 | WO2018107170A1 | Small modular reactor power plant with load following and cogeneration capabilities and methods of using | 13 |
| 4 | WO2015085241A1 | Slimm-scalable liquid metal cooled small modular reactor | 12 |
| 5 | US20220223302A1 | Modular core molten salt nuclear reactor | 11 |
| 6 | RU2699229C1 | Low-power fast neutron modular nuclear reactor with liquid metal heat carrier and reactor core (versions) | 9 |
| 7 | US9275761B2 | Small modular reactor safety systems | 9 |
| 8 | US20190206580A1 | Small modular reactor power plant with load following and cogeneration capabilities and methods of using | 8 |
| 9 | WO2020225156A1 | Modular core molten salt nuclear reactor | 3 |
| 10 | WO2013188128A1 | Small modular reactor safety systems | 3 |
Citation counts reflect influence within the searched corpus and skew toward older filings; they are not a measure of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for filing strategy
The dataset is small enough that individual families carry real weight — the patterns below are about where claim space is occupied and where it is not.
Activity has cooled from its 2020 high
Every tracked assignee reports zero filings in the most recent year. Combined with the drop from a 2020 peak of 9 to a 2022 midpoint of 2, this looks like a field where earlier filers staked claims and few have followed with continuations recently.
Nearly all claims sit in one subclass
The near-total concentration in G21C means the competitive contest is over core design, vessel geometry and reactor internals — not over the plant-level or business-process layer, where only a handful of records appear.
Core design and liquid-metal cooling anchor the field
The two most-cited families address optimised fuel core design and a scalable liquid-metal-cooled reactor architecture, both cited 25 times. Load-following and cogeneration claims follow closely, suggesting examiners and applicants alike treat these as the reference points to design around.
Co-invention is rare and narrow
Only four co-assignee pairings appear across the set, and they cluster around one inventor group rather than reflecting broad cross-company collaboration. Most families in this landscape are filed by a single assignee.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to small modular reactor technology, with the prior art for and against each one.
Who holds the claims
Assignee activity here is broad but shallow: no organisation shows filings in the latest tracked year, and the receiving-office spread suggests protection is being sought across several jurisdictions rather than concentrated in one.
Europe and the US lead office-level filing
The European Patent Office and the US receive the largest share of filings, with WIPO/PCT applications close behind — consistent with applicants seeking multi-jurisdiction coverage for reactor designs rather than filing domestically only.
No assignee is currently active in the newest year
Every organisation tracked in the recent-momentum view — including Thorizon, Westinghouse Electric, Advanced Reactor Concepts, STC UNM and Korea Hydro & Nuclear Fuel — shows zero filings in the latest year, which is more consistent with publication lag than with a sudden industry-wide pause.
A small inventor cluster drives joint filings
The strongest co-assignee links all involve the same lead inventor paired with different collaborators, pointing to one research group rather than a broad industry alliance behind the co-filed families.
| Assignee | Recent year | YoY |
|---|---|---|
| THORIZON HLDG BV | 0 | — |
| SMR Inventec Co., Ltd. | 0 | — |
| Westinghouse Electric Company | 0 | — |
| Advanced Reactor Concepts LLC | 0 | — |
| STC.UNM (Science and Technology Corporation, University of New Mexico) | 0 | — |
| Korea Nuclear Fuel Co., Ltd. | 0 | — |
| Korea Hydro & Nuclear Power Co., Ltd. | 0 | — |
| Ulsan National Institute of Science and Technology (UNIST) | 0 | — |
Where to take this analysis
This landscape is a starting point for scoping freedom-to-operate and identifying where a new filing would sit relative to existing claims.
Check freedom-to-operate against the top-cited families
The core-design and liquid-metal-cooling families cited 25 times each are the most likely prior art to collide with new core or coolant-loop claims. Map any proposed design against their independent claims before drafting.
Explore in EurekaWatch for publication-lag catch-up
The zero-filing latest year across every assignee is very likely an artefact of the roughly 18-month gap between filing and publication, not a real stop in R&D. Re-run this search in a year to see which assignees resume filing.
Explore in EurekaTest the under-claimed branches
Factory-fabrication joints, load-following control algorithms and passive decay-heat removal for microreactors show thin coverage relative to core design. A well-scoped claim in one of these areas faces less crowded prior art.
Explore in EurekaCommon questions about SMR patent activity
Within this dataset, the most-cited families are US20180277260A1 on optimised nuclear fuel core design and US20160329113A1 covering the SLIMM scalable liquid-metal-cooled reactor, each cited 25 times, alongside WO2018107170A1 on load-following and cogeneration capability. These citation counts measure influence within the searched corpus rather than commercial deployment, but they mark the claims that later filers most often had to design around. No single assignee dominates filing volume across the full 33-family set, which is unusual for a field this technically narrow.
Filing peaked at 9 in 2020 and had fallen to 2 by the 2022 midpoint, with every tracked assignee showing zero filings in the most recent year. That pattern looks like a slowdown, but publication lags filing by roughly 18 months, so recent years are structurally undercounted in any patent dataset. The honest read is that visible filing has cooled from its 2020 high, with the true current pace not yet observable.
32 of the 33 families in this set classify under G21C, the nuclear reactor subclass, meaning claim activity concentrates heavily on core design, vessel architecture and reactor internals. Only 5 records touch G21D, the nuclear power plant subclass, and single incidental records appear in unrelated classifications. This tells a filer that the reactor-core layer is comparatively crowded while plant-level systems claims are thinner.
Based on this landscape, factory-fabrication module joints, load-following control algorithms, integral vessel internals for liquid-metal coolant, passive decay-heat removal for microreactors and cogeneration heat-offtake interfaces all show thinner coverage than core reactor design. These sit inside the search scope but did not surface among the heavily-cited or heavily-filed clusters, making them reasonable areas to scope a first claim with less crowded prior art.
Ownership is broad rather than concentrated: across 33 families there is no assignee with a clear runaway lead, and only 4 co-assignee pairs appear, mostly linked through a single inventor group. Recent-year momentum data shows every tracked organisation, including Westinghouse Electric, Advanced Reactor Concepts and Korea Hydro & Nuclear Fuel, at zero filings in the latest year. That combination of low concentration and stalled recent activity suggests the field remains open to new entrants willing to file now.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.