When I travel with a lot of cash (usually international), I put most of it in a compartment in my computer bag. I do this at home or way before I reached Security. I used to carry it on my person but not since the NOS. I have never had a problem. I don't know if the Xray machine can see the cash but I have never been questioned. My computer bag is a wheeled case with many compartments so it's not easy for somebody to find the cash. Of course somebody can walk off with it but I have never lost anything going through security.