I believe Uranium Ingots themselves have the actual fuel power value not the reactors. In essence I am under the impression that all reactors are equal in terms of fuel efficency.

1 unit of Uranium Ingots will provide the same overall power in a Small Vanilla Reactor on a small ship as a Hyperion 7 on a station. In order to have different values mods need custom fuels.

He could be asking about the block cost compared to power produced, or even space efficiency. Although the second one is largely easy to figure out.

No idea why nobody has mentioned this yet.

Ok so here are some numbers I calculated. All calculations are for large grids and are rounded to the 5th decimal place.
(I only did calculations for reactor components (rc) and superconductor components (scc) because they are the most expensive)

Power Output per meter^3:
Hyperion 1 (1x1x1): 3.85MW/m^3
Hyperion 3 (3x3x3): 3.79259MW/m^3
Hyperion 5 (5x5x5): 4.096MW/m^3
Hyperion 7 (7x7x7): 5.97085MW/m^3
Hyperion 9 (9x9x9): 7.02332MW/m^3
Regular Large Reactor: 0.71111MW/m^3

Power Output per reactor component (rc):
Hyperion 1 (1x1x1): 0.15MW/rc
Hyperion 3 (3x3x3): 0.2MW/rc
Hyperion 5 (5x5x5): 0.5MW/rc
Hyperion 7 (7x7x7): 1MW/rc
Hyperion 9 (9x9x9): 1.25MW/rc
Regular Large Reactor: 0.15MW/rc

Power Output per superconductor component (scc):
Hyperion 1 (1x1x1): 6MW/scc
Hyperion 3 (3x3x3): 8MW/scc
Hyperion 5 (5x5x5): 20MW/scc
Hyperion 7 (7x7x7): 40MW/scc
Hyperion 9 (9x9x9): 50MW/scc
Regular Large Reactor: 3MW/scc

Final conclusion: All 5 reactors are defiantly worth it assuming you want to spend the time gathering that much more components and uranium.

My simple question here is: How much uranium ingot does a hyperion-7 reactor need per day if the reactor has to supply a base that consumes 10 GW ? (... is it possible to harvest so much uranium to drive a hyperion-7 continuously ?)

Anything is possible. The question is how much FPS you have to sacrifice for it.

I have measured it today for a hyperion-7 reactor: At 1 GW it consumes approximately 1 kg uranium ingot in 2.5 seconds and at 213 MW it consumes 1 kg uranium ingot in 10 seconds. For to compensate the consumption I had to run 5 refineries simultaneously.
That means that it is nearly impossible to run this reactor because of a such high uranium consumption that you hardly can harvest so much ore to feed the refineries.

For 300 MW demand I use RTGs instead now.