Nuclear Reactor Control Rod Patents: Top Companies & Filing Trends 2026
A patent landscape analysis of nuclear reactor control rod technology: 3,424 records, filing trends since 2017, IPC composition, top assignees and the most-cited drive mechanism patents.
Filing growth = 2021 (36 records) → 2024 (16); 2024 is the last year we treat as complete. Top-5 share = the 5 largest assignees ÷ all 3,424 records in scope (CR5), not the ranked leaders only.
What the control rod patent record actually shows
Control rod technology is one of the most claim-dense corners of nuclear reactor engineering: drive mechanisms, coil assemblies and cooling paths for the drive apparatus recur across decades of filings from a small group of reactor vendors. The record spans 2015 through the current data cut-off, drawing on 3,424 published records classified under G21C and related IPC subclasses. Patent families, not raw document counts, are the fairer unit here because a handful of assignees file heavily across multiple jurisdictions for the same underlying design.
The picture that emerges is concentration at the core — drive mechanism and cooling hardware — with a long tail of single-filing entrants working peripheral problems like measurement, shielding and alloy composition. That split matters for anyone deciding where to file next.
Filing trend and technology composition
Two views of the same 3,424-record dataset: how filing volume has moved year over year, and which IPC subclasses carry the claims.
A 2017 peak, then a step down
Filings hit a peak of 56 in 2017. By 2021 the annual count had settled to 36, and it fell further to 16 by 2024 — a -56% move over that three-year span. Because publication typically lags filing by around 18 months, the most recent one or two years in the chart will fill in further and should not be read as the field going quiet.
Publication lags filing by roughly 18 months, so 2025 onwards are still filling in. Growth rates on this page therefore end at 2024; running them to the last bar would understate the field.
G21C dominates; everything else is a sliver
G21C (nuclear reactors) appears on 97.5% of the 3,424 records in scope — effectively the home class for this topic. G21D (nuclear power plants) follows at 9.1%. Everything past that — measuring instruments, radiation shielding, electric motors, alloys, material testing — sits at or under 1.6%, meaning claim activity outside the reactor-and-plant core is thin and scattered rather than organised around a second hub.
Shares are the percentage of the 3,424 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 control rod patents
Cooling unit for nuclear reactor control rod driving apparatus (US8558417B2)
A cooling unit cooling a coil assembly that generates electromagnetic force for driving a nuclear reactor control rod, and including a coil surrounding a driving shaft of the nuclear reactor control rod so as to generate the electromagnetic force; a coil housing surrounding the coil so as to enclose the coil; a cooling shroud-shell forming a cooling flow path between the cooling shroud-shell and the coil housing, whereby a cooling fluid for cooling heat that is generated in the coil passes through the cooling flow path; and a plurality of cooling fins disposed on the cooling flow path in a radial direction so as to allow heat to be effectively exchanged between the coil and the cooling fluid.Filed by KEPCO Engineering & Construction Company, published 2013-10-15.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20100316177A1 | Control rod drive mechanism for nuclear reactor | 149 |
| 2 | US20110222640A1 | Control rod drive mechanism for nuclear reactor | 133 |
| 3 | US4072563A | Industrial technique for an integral compact reactor | 107 |
| 4 | US20120076254A1 | Compact nuclear reactor | 90 |
| 5 | US5182484A | Releasing linear actuator | 84 |
| 6 | US6061412A | Nuclear reaction protection system | 80 |
| 7 | US6246740B1 | SIC-composite material sleeve and process for producing the same | 73 |
| 8 | US2863815A | Nuclear reactor | 66 |
| 9 | US5563922A | Method and system for indicating the position of control rods of a nuclear reactor | 65 |
| 10 | US4678623A | Modular head assembly and method of retrofitting existing nuclear reactor facilities | 65 |
Citation counts favour older filings simply because they have had longer to accumulate citations inside the searched corpus — treat this as a signal of influence on later design work, not a ranking of current relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Four readings of the same dataset, aimed at where a filing or freedom-to-operate decision would actually change.
The core is crowded, the edges are not
Just five assignees account for 46.1% of all 3,424 records in scope, and the top ten reach 57.4%. That leaves a long tail of single- or few-filing entrants working the remainder — a pattern typical of mature reactor hardware where the drive mechanism and cooling architecture are largely staked out.
Volume has stepped down since the 2017 peak
Annual filings peaked at 56 in 2017 and had fallen to 16 by 2024, a -56% move from the 2021 level of 36. The two most recent years in the chart are still incomplete because publication lags filing by roughly 18 months, so this should be read as a step down through 2024, not a live trend.
One dominant class, a distant second
G21C carries 97.5% of the 3,424 records in scope; G21D, the plant-level class, trails at 9.1%. Every other subclass — measurement, shielding, motors, alloys, testing — sits under 2%, which points to thin, scattered activity outside the reactor core rather than a developed secondary cluster.
Drive mechanism patents anchor the citation network
The most-cited records in this set are consistently control rod drive mechanism and compact reactor filings, with the leading record drawing 149 citations. That pattern reflects influence on later engineering, not current legal strength — older filings have simply had more time to accumulate citations inside the searched corpus.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to nuclear reactor control rod patent landscape, with the prior art for and against each one.
Where to take this analysis
The dataset points to a few concrete next steps depending on what a team needs to decide.
Map freedom-to-operate against the concentrated core
With 46.1% of records held by five assignees, a new drive mechanism or cooling design should be checked against those portfolios first, not against the full ranked list.
Explore control rod patents in EurekaWatch the peripheral classes for open claim space
Radiation shielding, material analysis and alloy composition each sit under 2% of records — worth a closer look before assuming the field is fully claimed.
Run a white-space search in EurekaTrack the post-2024 filing signal as it fills in
The 2025-2026 filing counts are still incomplete due to publication lag; revisit the trend once another cycle of data has come through.
Set a filing alert in EurekaCommon questions about control rod patents
Filing in this field is concentrated: the top five assignees together account for 46.1% of all 3,424 records in scope, and the top ten reach 57.4%. That leaves a long tail of entrants — mostly national labs, engineering firms and single-project filers — holding the remaining share. Anyone assessing freedom-to-operate should check the concentrated leaders first, since that is where the bulk of drive mechanism and cooling claims sit.
Annual filings peaked at 56 in 2017 and have declined since, reaching 16 by 2024 — a -56% move from the 36 filings recorded in 2021. Because publication lags filing by roughly 18 months, the 2025 and 2026 figures in any chart are still incomplete and understate true filing activity. Treat 2024 as the last year that can be compared reliably against earlier peaks.
The dominant class is G21C (nuclear reactors), present on 97.5% of the 3,424 records in scope, with G21D (nuclear power plants) a distant second at 9.1%. Beyond those two, activity is thin: measuring instruments, radiation shielding, electric motors, alloys and material testing each appear on 1.6% or fewer records. That spread suggests most inventive effort concentrates on the reactor and plant level rather than on adjacent hardware or materials.
The most-cited records in this dataset are control rod drive mechanism and compact reactor filings, led by a record with 149 citations. High citation counts favour older patents simply because they have had more time to accumulate citations within the searched corpus, so this is better read as a measure of influence on later engineering than of current legal or commercial importance. A newer, less-cited filing can still be more relevant to a live design question.
Based on IPC composition, the classes furthest from the reactor core — radiation protection and shielding (1.4% of 3,424 records), material analysis and testing (0.8%), and alloys (1.0%) — carry the lightest claim density. That does not mean these areas are technically unsolved, but it does mean fewer barriers exist there compared with the heavily filed drive mechanism and cooling space. Teams looking for open claim space should start with these lighter-density classes rather than the crowded reactor core.
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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.