SMR Integral Pressurized Reactor Patents: Leaders & White Space 2026
Filing growth compares 2021 (12 records) with 2024 (1) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 502 records in scope (CR5), not by the ranked leaders only.
What the integral pressurized reactor patent record shows
An integral pressurized reactor packages the steam generator, pressurizer and, in some designs, the reactor coolant pumps inside a single reactor vessel, rather than distributing them across separate loops. That compact arrangement is central to most small modular reactor (SMR) designs because it removes large-bore primary piping and the loss-of-coolant scenarios that go with it. The dataset behind this page covers 502 published records filed or published between 2015 and mid-2026 and classified under G21C, tracking who has claimed which parts of that integral architecture.
The record set is concentrated: a handful of assignees, mostly established reactor vendors and national nuclear authorities, account for most of the filings, while the classification spread shows heavy claim density in core reactor design and comparatively little in control systems, material testing or radiation shielding as applied specifically to integral designs.
Filing trend and technology composition
The two charts below track when integral pressurized reactor filings were made and where they sit across the IPC classification system. Read the most recent one or two years as incomplete rather than as a genuine drop-off.
A sharp rise and fall around 2021
Filings climbed from 5 in 2017 to a peak of 12 in 2021, then fell to 1 by 2024 — a decline of 92% over that three-year span. Because publication trails filing by roughly 18 months, 2025 and 2026 figures are still filling in and should not yet be read as confirmation of a continued decline.
Claim density sits almost entirely in G21C
98.6% of the 502 records carry a G21C nuclear reactor classification, with G21D nuclear power plant classifications appearing in 20.3%. Beyond those two, coverage drops off fast: steam generation equipment (F22B) appears in 7.6% of records, and pumps, valves, shielding, testing and control classes each sit at 4.2% or below.
Shares are the percentage of the 502 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
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Try EurekaThe most-cited prior art and a representative claim
Pressurized water reactor with upper vessel section providing both pressure and flow control
A pressurized water reactor (PWR) includes a vertical cylindrical pressure vessel having a lower portion containing a nuclear reactor core and a vessel head defining an integral pressurizer. A reactor coolant pump (RCP) mounted on the vessel head includes an impeller inside the pressure vessel, a pump motor outside the pressure vessel, and a vertical drive shaft connecting the motor and impeller. The drive shaft does not pass through the integral pressurizer. The drive shaft passes through a vessel penetration of the pressure vessel that is at least large enough for the impeller to pass through.Filed by BWXT MPOWER, INC., published 2013-05-02 — illustrates how vessel-head integration of pump and pressurizer functions is claimed.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20100316181A1 | Integral helical coil pressurized water nuclear reactor | 186 |
| 2 | US4072563A | Industrial technique for an integral compact reactor | 107 |
| 3 | US20120076254A1 | Compact nuclear reactor | 90 |
| 4 | US6795518B1 | Integral PWR with diverse emergency cooling and method of operating same | 89 |
| 5 | US20130336441A1 | Small modular reactor safety systems | 58 |
| 6 | CN101154472A | 一体化低温核供热堆 | 57 |
| 7 | US5024801A | Reactor core model update system | 56 |
| 8 | US3849257A | Guide structure for control elements | 52 |
| 9 | US20130287157A1 | Instrumentation and control penetration flange for pressurized water reactor | 49 |
| 10 | US5963611A | Steam separator, nuclear power generation plant, and boiler apparatus | 45 |
Citation counts reflect a searched corpus and favour older filings; treat them as a measure of influence on later designs, not of current commercial relevance.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Three patterns stand out once the ranking, the trend and the classification data are read together.
A narrow leading group, not a crowded field
The top five assignees combined account for 56.2% of the 502 records in scope, and the top ten reach 71.7%. New entrants filing core vessel-integration claims are filing into space already dense with prior art from established reactor vendors and national labs.
A filing peak that has already passed
Filings rose to a peak of 12 in 2021 and fell to 1 by 2024. That is a real decline over a three-year window that predates the 18-month publication lag affecting 2025-2026 data, suggesting the initial wave of core-architecture claims has largely been staked out.
Claims cluster on the reactor itself, not the plant around it
Nearly every record touches G21C nuclear reactor claims, but coverage of nuclear power plant systems (G21D, 20.3%), steam generation (F22B, 7.6%) and control systems (G05B, 1.8%) is thinner. That gap is where integration-level and controls-focused claims still have room.
Filing is spread across six major offices
The United States leads with 135 records, followed by the European Patent Office at 82, the United Kingdom at 51, China at 42, Japan at 36 and South Korea at 30. That spread indicates integral pressurized reactor designs are being protected across multiple jurisdictions rather than concentrated in a single market.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to small modular reactors: integral pressurized reactor patent landscape, with the prior art for and against each one.
Where to take this analysis
The dataset points to a field with a settled leading group and a narrowing filing rate. The next steps depend on whether the goal is freedom-to-operate, partnership scouting or identifying open claim space.
Map freedom-to-operate against the leading holders
With 71.7% of records held by ten assignees, a freedom-to-operate review for any new integral vessel design should start with those holdings rather than a broad novelty search.
Run a claim comparison in EurekaTrack the under-claimed branches
Control systems, material testing and radiation shielding classes each sit under 2% of records specific to this search — worth checking against the broader G21C corpus for context before committing R&D there.
Explore adjacent classifications in EurekaWatch for the next filing wave
The 2021 peak has passed and 2025-2026 data is still incomplete; monitoring new publications as they land will show whether a second wave of controls- or safety-system claims is emerging.
Set up filing alerts in EurekaCommon questions about integral pressurized reactor patents
An integral pressurized reactor houses the steam generator, pressurizer and often the reactor coolant pumps inside a single pressure vessel, instead of connecting them through external loop piping as in a conventional PWR. This eliminates large-bore primary coolant piping and the large-break loss-of-coolant accident scenarios associated with it, which simplifies the safety case. Most small modular reactor designs from established vendors use this architecture, which is why the patent activity in this dataset is concentrated so heavily in the G21C reactor classification.
The ranked leaders in this dataset are established reactor vendors and national nuclear authorities, with the top five assignees together accounting for 56.2% of the 502 records in scope and the top ten reaching 71.7%. This concentration means a small number of organisations control most of the core vessel-integration claim space. Anyone evaluating a new design should treat those holdings as the starting point for a freedom-to-operate review rather than assuming the field is open.
Filings rose from 5 in 2017 to a peak of 12 in 2021, then fell to 1 by 2024, a decline of 92% over that three-year window. That drop is measured against 2024, the most recent year that can be treated as complete, so it is a genuine slowdown rather than an artifact of publication lag. Figures for 2025 and 2026 will still rise as pending applications publish, roughly 18 months after filing, so it is too early to read those years as confirming a further decline.
The classification data shows heavy density in core reactor design (G21C, 98.6% of records) and nuclear power plant systems (G21D, 20.3%), but much lighter coverage in control and regulating systems (G05B, 1.8%), material analysis and testing (G01N, 1.8%), and radiation shielding (G21F, 2.0%) as applied to integral designs specifically. Those thinner branches are where new claims are less likely to run into dense prior art, though a full novelty search against the wider G21C corpus is still needed before filing.
The United States receives the most filings in this dataset at 135 records, ahead of the European Patent Office at 82, the United Kingdom at 51, China at 42, Japan at 36 and South Korea at 30. This spread across six major offices indicates that assignees are protecting integral reactor designs in multiple jurisdictions rather than relying on a single home market, which is typical for technology aimed at export-oriented SMR programmes.
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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.