As the title sais those three liquids should be unobtainable. They are not intended to be used by the player, they are only for internal use in BigReactors. They are causing bugs in other mods because they are not fully implemented as it is not needed.

Actually that's not entirely true. You can melt the liquids (I believe you might need some addon for it) to ingots using Tinkers Construct. I've seen people do exactly that

ExtraTiC does that but shouldn't. It is one mod I know of that can cause crashes with those fluids.

If you are using ExtraTiC does that not add motel Yellorium, and not use the actual liquid Yellorium, just as a point of interest

It uses the original fluid.

Take a look at this issue, the developer himself explained it: erogenousbeef-zz/BigReactors#475