I mean, Ontario runs the Bruce nuclear plant which is the second largest in the world in terms of the power it generates at 6,610 MW, Japan gets the top nod with a plant that generates 7,965 MW.
Kashiwazaki-Kariwa ? It has been not in full commercial service for close to two decades now. Only one unit recently restarted this year. 6 units are offline now
There are two South Korean plants (Kori, Hangul) larger than Bruce
You could be right about the Korean plants. I only relied on google to give me the top 5 nuclear plants active in the world. The Korean plants you mention were not on the list.
Wikpedia has more info, plus WNN and other industry publications usually are more up-to date.
Kori[1] has 7 operational units today and 1 commissioning and 1 under construction
Hansul[2] has 8 operational units and another 2 more under construction.
All 4 new units are APR-1400 reactors ~1400 MW capacity. Kori should retains its top position, Saeul-3 in Kori Phase II has already reached criticality in April.
Tianwan in China will come close but its 7/8 units are slightly behind in construction than Saeul-3/4 in South Korea, plus the plant is also bit smaller at 6600MW now . The Russian VVER-1200 design China are using is also slightly smaller than Korean APR-1400.
There are two South Korean plants (Kori, Hangul) larger than Bruce