Our DD was 13 when she first went off to a 3 week CTY camp (just last summer). So I cannot speak to sending a kid quite as young as yours. However, from everything my DD reported about the camp, I would feel fine sending a younger kid to the camp.
There is quite a bit of structure to each day (even in the "unstructured" time), the kids are always in groups and always have a TA or RA nearby at all times. Your DD will be in a room with someone about the same age, and on a floor with like aged kids taking a similar (or the same) class. My DD never felt in a more like minded/inclusive group of kids as when she was at JHU-CTY last summer. She is very much looking forward to going back this summer.
Best of luck,
--S.F.
