Source: /n/wiki/Nuclear power plant, /n/wiki/List of tallest cooling towers, /n/wiki/Fukushima Daiichi Nuclear Power Plant, /n/wiki/Bruce Nuclear Generating Station, /n/wiki/Kori Nuclear Power Plant, /n/wiki/Nuclear power in France, /n/wiki/Chernobyl disaster, /n/wiki/List of nuclear power stations. Grounded 2026-09-14. Cartographer, 9NOSIS.
A nuclear power plant is, mechanically, a heat engine: fission heats water into steam, steam turns a turbine, and the leftover heat has to go somewhere. That "somewhere" is the physical constraint every reactor site design starts from — not the reactor, the coolant. This map is organized by cooling-water source, because the source determines where a reactor CAN be built, and every named incident below traces back to that same fact.
HOW A REACTOR SHEDS ITS HEAT
============================
[reactor core] --steam--> [turbine] --> [condenser]
|
secondary cooling circuit
|
+-------------+-------------+-------------+
| | | |
SEAWATER LAKE WATER RIVER + TOWER COOLING POND
(coastal) (freshwater (inland, (contained,
once-through) evaporative) closed site)
| | | |
Fukushima Bruce France's Chernobyl
Onagawa (Ontario) 56-reactor (Pripyat)
Kori (Korea) fleet
Plants built directly on a coastline draw cooling water straight from the sea and need no cooling tower for the ultimate heat sink — but the same coastline that supplies free, unlimited coolant is also the exposure.
Fukushima Daiichi (Japan). TEPCO's own seawater intake pumps for all four reactor units were flooded and disabled by the 11 March 2011 tsunami. The powerful tsunami and did not raise it. Loss of the seawater cooling path — not the earthquake itself — is what forced the subsequent meltdowns.
Onagawa (Japan), the direct contrast. Operated by Tohoku Electric, sited closer to the earthquake's epicenter than Fukushima, using the same coastal seawater-cooling design — but built with taller, more robust seawalls. It avoided a severe accident entirely. Same design principle, same event, different physical margin, opposite outcome. The map's argument here is not "coastal siting is dangerous" — it is that the seawall height, a single concrete design number, was the entire difference.
Kori (South Korea). A large multi-reactor coastal complex on Korea's southeast coast — the third structural example of the same siting logic: put the plant where cooling water is free and abundant, accept the coastal hazard profile as the tradeoff.
Bruce Nuclear Generating Station (Ontario, Canada). Sited on the eastern shore of Lake Huron. Cooling water is drawn directly from the lake for eight CANDU reactors across two plants (A and B). This is a once-through freshwater design rather than seawater or a closed cooling-tower loop — no tidal or storm-surge exposure of the Fukushima kind, but a hard geographic requirement: an inland reactor of this scale needs a Great Lake, not a river, to supply cooling at this volume. Until 2016 it was the world's largest fully operational nuclear generating station by reactor count.
Nuclear power in France. The source states directly that French reactors are "located away from the coasts and obtain their cooling water from river[s]" — a deliberate national siting pattern, not an accident of geography. Some plants have cooling towers using evaporative cooling; others draw and return water directly to a lake or river, with regulated limits on the temperature of water released back into "the final heat sink." Towers at Civaux and Golfech are named among the world's tallest cooling-tower structures — the visible skyline signature of this design choice.
The 2022 drought — river cooling's physical ceiling. The source records that in early September 2022, 32 of France's 56 reactors were shut down for maintenance or technical problems, during what the article calls Europe's driest summer in 500 years. The drought reduced the volume of river water available for cooling — a hard physical constraint distinct from the Fukushima flood risk: not too much water, but too little. A river-cooled fleet has a low-flow ceiling that a coastal or lake-cooled plant does not share in the same way.
Chernobyl (Pripyat, Ukraine, then Soviet Union). Used fuel from units 1-3 was stored in the plant's own cooling pond — a constructed, closed body of water on-site rather than a connection to a river, lake, or sea. This is a structurally different cooling geography than any of the above: the site does not depend on an external freshwater or seawater body for its cooling infrastructure at all in the same open-exchange sense.
Beyond siting, France's nuclear fleet carries a second, non-cooling-related physical-reality fact worth mapping alongside it: 71.67% of French electricity came from nuclear power in 2018 — the highest percentage of any country in the world — and all 56 reactors are run by a single state-owned operator, EDF. The 2022 drought and the parallel maintenance shutdown of 32 reactors happened to the same single-operator fleet at the same time: a national grid dependent on one company's cooling-constrained river-sited reactors, all exposed to the same summer.
Chernobyl and Fukushima are the only two nuclear accidents ever rated at the maximum INES severity level (Level 7) — but their causes sit at opposite ends of the same map:
| | Chernobyl (1986) | Fukushima (2011) | |---|---|---| | Cooling source | closed on-site pond | open seawater intake | | Trigger | reactor design flaw + operator error, no external cause | external natural disaster (tsunami) disabling functioning safety systems | | What failed | the reactor itself, during a test | the cooling-water supply chain, after the reactor had already scrammed safely |
Fukushima's reactors shut down correctly when the earthquake hit; it was the loss of seawater cooling — Onagawa's seawall margin, absent at Fukushima — that turned a successful shutdown into a meltdown. Chernobyl had no external trigger at all. Same rating, opposite physical story.
Every incident above is the same underlying fact restated: a reactor's physical site is chosen by where cooling water can be gotten, in what volume, and how reliably — sea, lake, river, or a contained pond — and every named failure or near-failure traces back to that same choice meeting its physical limit: too little seawall (Fukushima), too little river flow (France 2022), or a design that needed no external water source engaging its own flaw with nothing outside to blame (Chernobyl).