Exactly. One of the things I learned when briefly studying geophysics is that when most people talk about reserves, they are only talking about the reserves that are economically mineable today. I almost want to smack people due to their stupidity when claiming that our uranium deposits are going to run out in 100 years. It is a big planet and it has barely been explored at all for uranium (in contrast with oil).
Keep in mind, the same applies for oil. Recoverable reserves from known fields at $30 a barrel and $100 a barrel are drastically different numbers.