Out of curiosity how long will uranium supplies last if we increase our reliance on it as a fuel source (serious question I don't know the answer).
There are 3 types of categorisations for uranium resources.
The first distinguishes conventional uranium resources, where uranium is the main product of extraction operations, from unconventional uranium resources, where uranium is extracted as a minor by-product when extracting other materials.
The second categorisation is based on the level of confidence that the resources exist given how much exploration has been done. This categorisation distinguishes between identified resources, inferred resources, prognosticated resources and others categories.
The third categorization is by extraction cost.
Conventional resources where uranium is the main product: Estimated 14.8 million tonnes. Among them is 4.7million tonnes that is basically "in hand" - we know they exist because we can see them in mines that are already dug or in analyzed rock samples, or can be inferred from geological surveys.
The remaining part of conventional resources is about 10 million tonnes of "undiscovered" or "speculative" resources, based on limited geological survey. It is most likely an underestimate as only about 2/3rd of all countries have reported deposits in this category. Australia, for example, has not.
Finally there are unconventional resources. That´s another 22 million tonnes. These are associated with phosphates and also fall within the cost category of less than $130/kg.
One important reference point to note is that in the whole 60-year history of the nuclear era through today, the total amount of uranium that has been produced adds up to about 2.2 Mt.
That´s how much there is. How long will it last? If it´s used at the rate we use it today, the answer is that the 4.7 million tU of "identified resources" would last eight to nine decades.
The "total conventional resources" of 14.8 million tU, again at current usage rates, would last several hundred years.
And if we next add in uranium associated with phosphates, we have enough uranium to last 600 to 700 years.
Again this all assumes unchanged usage rates and unchanged technology and unchanged efficiency of reactors.