Can I cover these pipes in my basement floor with concrete?
If you are going to concrete this, you need to extend the sewer cleanout or you'll be taking a hammer to the concrete when you need that (if you even remember where it is, then), and you'll need to sleeve the copper waterline with something to protect it from the concrete, or you'll be having a massive leak and needing to hammer the concrete to fix that. Both of those penetrations will want an appropriate sealant / caulk for the radon containment job, as well.

At 18x18 inches you could possibly also adapt a standard radon-sealing sump cover to cover the hole and attach a radon vent pipe to, though this looks like the sort of overly finished basement where that might be difficult as you're built right up to the hole.