Skip to content
nuclear•chain

Which SMRs are actually being built

Every design here is ranked by what a regulator has actually done, not by what the developer has announced. Of 19 tracked designs, 8 have a construction permit or better and one is generating power. The rest are under review or have not yet filed an application at all.

Designs tracked
19
each with a docket
Permitted or better
8
of 19
Need HALEU
12
63% of designs
No application filed
6
pre-application or paper
The fuel problem

12 of 19 designs need HALEU — uranium enriched above 5%. Western production currently runs at roughly 900 kilograms a year from a single demonstration cascade, while one small reactor's first core needs several tonnes. 4 of the 8 designs already permitted or building are in that queue. A reactor can be licensed, financed and built and still have nothing to run on.

Some of these are small enough to travel on a truck — microreactors that ship in containers are covered separately.

Design Developer Regulatory position MWe Fuel Regulator Units announced
KLT-40S (Akademik Lomonosov) Rosatom Operating 35 LEU Rostechnadzor (Russia) —
BWRX-300 GE Vernova Hitachi Nuclear Energy Under construction 300 LEU CNSC (Canada) and US NRC 47
ACP100 (Linglong One) China National Nuclear Corporation Under construction 125 LEU National Nuclear Safety Administration (China) —
RITM-200N Rosatom Under construction 55 LEU Rostechnadzor (Russia) 8
Project Pele BWX Technologies Under construction 2 HALEU US Department of Defense / Department of Energy authorisation —
Hermes Kairos Power Under construction 35 MWt HALEU US NRC —
Natrium TerraPower Permitted 345 HALEU US NRC —
Hermes 2 Kairos Power Permitted 70 MWt HALEU US NRC —
NuScale US460 (VOYGR) NuScale Power Design approved 77 LEU US NRC 61
Rolls-Royce SMR — Under review 470 LEU UK ONR and Environment Agency —
SMR-300 Holtec International Under review 300 LEU US NRC and UK ONR 10
Xe-100 X-energy Under review 80 HALEU US NRC 16
Aurora Oklo Inc. Under review 15 HALEU US NRC —
IMSR (Integral Molten Salt Reactor) — Pre-application 195 HALEU US NRC and CNSC (Canada) —
ARC-100 — Pre-application 100 HALEU CNSC (Canada) —
BANR BWX Technologies Pre-application 17 HALEU US NRC 8
Aalo-1 — Pre-application 10 HALEU US Department of Energy authorisation pathway 12
eVinci Westinghouse Electric Company Pre-application 5 HALEU US NRC —
Kaleidos — Pre-application 1 HALEU US Department of Energy authorisation pathway —

"Units announced" counts entries in the Global Nuclear Power Tracker carrying this design's model name, at any status including announced and cancelled. A high number is a measure of promotion, not of progress — compare it against the regulatory position beside it.

Sources