You can't look at world reserves of uranium. You have to look at world reserves of U235 which makes up about 0.76% of all Uranium. You also can't take the total amount, but have to take the commercially viable amount and the amount of energy Uranium contains cannot be converted 1-to-1 to electrical energy.

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>The world's present measured resources of uranium (6.1 Mt) in the cost category less than three times present spot prices and used only in conventional reactors, are enough to last for about 90 years. This represents a higher level of assured resources than is normal for most minerals.

Source: World Nuclear Association an organization promoting nuclear energy.

From our current perspective, when comparing to our previous industrial development, 90 is pretty good. But nowhere near enough in the long term and we'd have to fall back to renewable again unless we use breeder reactors which would improve the sustainabiliy of nuclear or figure out fusion.

So, while nuclear does have some advantages from present knowledge, we may as well skip the 90-year nuclear phase and go for renewables straight away.