The description of the mod says that its a mid-late game power source. Actually, building it is so easy, that its the perfect power source from relatively early game. In the world where i discovered this, my first querry was running from the reactor.
3x3x4 with one rod.Tuned the control rod a bit, powered my base,and the (bc) querry was at a ridiculious speed.

I suggest generating less amount of yellorium by default (probably 1 separated ores / chunk), because if this mod installed, then every other power gen is just obsolate at all time.

If you want less ores to generate, you can tweak the ore gen (unless it's not available in the configs, in which case it should be) to your liking. If you think it's too easy to build because it costs nothing but iron, coal/charcoal, and yellorite, then you can change the config setting to make it cost all steel; that may be pretty difficult depending on what mods you have available.

I tried to tweak the ore gen, but it not seems to have any effect. I get a little bit less, but still more than what i set.(I set 1 ore/cuslter, with 1-2 cuslters / chunk, then i came across a cluster with 5 ores.)
Yes, i set it to use steel.

That is strange that you still came across a 5-ore vein when you set it to 1 per. Maybe it's not BR generation that's controlling how yellorium is being generated? Depending on the pack, and if it came with another mod that controls oregen (CoFH is pretty popular for custom oregen) it might be overriding the BR generation. However, if this isn't the case in your setup, then I'm not sure.

This is not a bug, this is an opinion. If you find it too easy, you're welcome to alter the configs to make it "more difficult".

Nothing else altering yellorite generation, cohf core not picked it up on its own, and i do not added it.