How ually explicit is the Black Swan movie?

My 15 year old wants to see it, but I'm leery about the ual content. Opinions? (I'm a little bit of a prude when it comes to what my daughter sees... but by the same token, she's really not quite a little kid any more and I'm trying so hard not to treat her like one. I was about her age when I saw my first R rated movie. Of course it was the Terminator... so....)