Uranium is power. However, in our world of 2022, uranium is a problem. It’s become a non-starter for nuclear power. To us in the US, right now, nuclear power is a non-starter for energy. Nuclear power is a dying way to produce energy. Uranium is more of burden and hassle than other forms of energy..
Conversely, the US, Russia, and China have over 18,000 nuclear devices. In other words, uranium is military power.
But let’s first learn about Project Orion.
Essentially, project Orion, is the most direct and most powerful means to travel between stars. Even though fusion has been the promise of energy for 70 years, fission has worked and can be used for space travel.
So to the aliens, uranium reserves represent how far your country and species could travel, how many systems you could visit. Based on the reserves, they would be able to determine whether there is enough energy for us to reach them.
But to an alien entity, uranium represents the amount of power your country has to conduct space travel. That is, what threat you are to them. Uranium is space power.
Uranium is the raw power to start interplanetary exploration.