CPC technology class · G21

G21C - Nuclear Reactors

Nuclear reactors. 2,434 US utility patents granted 2015–2025, with the leading assignees and year-by-year grant trajectory.

Compiled by PlainPatent · May 15, 2026

2,434
US patents granted: #2/8
in G21: 27.1%
G21 class share: -3%
5-yr velocity

The verdict

According to USPTO PatentsView, Nuclear Reactors ranks #349 of 670 CPC technology areas - 2,434 US patents granted since 2015, with recorded grant volume down 3% over five years.

#349
of 670 CPC technology areas: 2,434
US patents granted, 2015–2025: Westinghouse Electric
leading assignee (265): -3%
grant velocity, last 5 yrs

How G21C's grant cadence moved

Between 2020–2024, G21C recorded 1,078 grants versus 1,106 in 2015–2019 (-3% equal-window velocity). Across complete years, output peaked in 2020 at 260 grants and bottomed in 2023 at 182 (+43% peak-over-trough). Lead assignee Westinghouse Electric Company LLC holds 10.9% of the class ; the top three share 22.8%.

Leaderboard read

G21C concentration, lead at 10.9%

Westinghouse Electric Company LLC leads this historical grant record at 10.9% of G21C - us corporation assignees hold 64% of class grants (1,100 of 1,728). Figures describe granted US utility patents in this CPC subclass, not current investment or legal strength.

Leader's share: 10.9%
Top three share: 22.8%
Lead over #2: 92

Where G21C sits inside G21

Among 8 subclasses in G21 (Nuclear PHYSICS; Nuclear Engineering), G21C ranks #2 and holds 27.1% of the parent class's 8,981 recorded grants. Sibling chips below are the other subclasses in the same parent class, not the nationwide volume/lead-share peers further down.

G21K 3,019 G21F 1,599 G21D 744 G21G 629 G21B 372 G21H 179 G21J 5

Rising assignees active in G21C

Company-wide grant multiples (2022–2024 vs 2019–2021) among assignees with ≥5 patents in this subclass. Growth is company-wide; class patent counts are subclass-specific.

#1 Bwxt Advanced Technologies LLC 24x 0 → 24 company-wide · 25 in G21C
#2 King Abdullah City for Atomic & Renewable Energy (K.A. CARE) 15x 1 → 15 company-wide · 8 in G21C
#3 Bwxt Isotope Technology Group, Inc. 12x 0 → 12 company-wide · 6 in G21C
#4 Carbon Free Holdings LLC 6.00x 1 → 6 company-wide · 9 in G21C
#5 Joint Stock Company “Science and Innovations” 5.33x 3 → 16 company-wide · 9 in G21C

G21C grants by year, peak 2020 (260)

US utility-patent grants per year in G21C, 2015–2025 - recent five years are down 3% versus 2015–2019.

Westinghouse Electric

265
Ge-hitachi Nuclear…

173
Terrapower

117
Bwxt mpower

79
Korea Atomic Energy…

78
Framatome

71
Nuscale Power

69
Holtec International

58
Kepco Nuclear Fuel

46
Hitachi-ge Nuclear…

42
Areva Np

42
Areva

32

What this shows Westinghouse Electric is the most active filer in G21C, holding 265 of the 2,434 patents in this class. Concentration at the top signals how contestable this technology area is for new entrants.

View data table

Top patent holders in CPC subclass G21C
Rank	Company	Patents in G21C
#1	Westinghouse Electric Company LLC	265
#2	GE-Hitachi Nuclear Energy Americas LLC	173
#3	Terrapower, LLC	117
#4	Bwxt mPower, Inc.	79
#5	Korea Atomic Energy Research Institute	78
#6	Framatome	71
#7	Nuscale Power, LLC	69
#8	Holtec International	58
#9	Kepco Nuclear Fuel Co., Ltd.	46
#10	Hitachi-ge Nuclear Energy, Ltd.	42
#11	Areva NP	42
#12	Areva GMBH	32
#13	SMR Inventec, LLC	32
#14	Korea Hydro & Nuclear Power Co., Ltd.	30
#15	Bwxt Advanced Technologies LLC	25
#16	Westinghouse Electric Sweden AB	25
#17	Global Nuclear Fuel-Americas, LLC	24
#18	Atomic Energy OF Canada Limited	23
#19	Battelle Energy Alliance, LLC	22
#20	Bwxt Nuclear Energy, Inc.	22

Footprint here vs. claim strategy

Each dot is a leading G21C assignee, placed by how many patents it holds in this class (horizontal) against its company-wide average claims per patent (vertical) - a read on whether the class is led by broad-but-shallow filers or focused deep-claim players.

Top 14 G21C assignees by class footprint. Bubble size = patents in G21C. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Classes near G21C's 2,434-grant footprint

Nationwide nearest neighbors for G21C (#349 of 670 by volume ; lead share 10.9%) - not the G21 parent-class siblings above.

Nearest by grant volume

G04G 2,450 E04D 2,409 B26B 2,460 A42B 2,474

Nearest by lead-assignee share

C12C 10.9% E21F 10.9% E01C 10.9% A01C 11.0%

Questions about G21C

Which company holds the most patents in G21C?

Westinghouse Electric Company LLC leads G21C with 265 patents (10.9% of the subclass). By PatentsView assignee type, us corporations account for 64% of class grants.

Which G21C assignees grew fastest recently?

Among assignees with ≥5 grants in G21C, Bwxt Advanced Technologies LLC shows the highest company-wide grant multiple (24x: 0 grants in 2019–2021 → 24 in 2022–2024) while holding 25 patents in this subclass. Growth is company-wide, not class-only.

How does G21C compare inside parent class G21?

Inside G21 (Nuclear PHYSICS; Nuclear Engineering), G21C ranks #2 of 8 subclasses by grant volume and holds 27.1% of the parent class total. The largest sibling is G21K (3,019 grants).

What to do with this data

G21C in context - here's where to go next.

Westinghouse Electric Company LLC leads G21C with 265 grants in this class. See full portfolio
G21C ranks #349 of 670 by grant volume among all tracked CPC technology areas. See the ranking
Inside parent class G21, the largest sibling subclass is G21K with 3,019 grants. Explore G21K

Figures reflect USPTO PatentsView grant data through 2026-05-15; pending applications not yet granted are not counted.

Methodology - G21C figures are USPTO PatentsView granted-utility totals for this subclass (2,434 grants in the tracked window).

Every figure on PlainPatent is rendered directly from USPTO source data, no number is typed in by an editor. This page draws directly on USPTO source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.