Prime attribute dependant on another prime attribute allowed under BCNF?
By definition, a relation is in BCNF if and only if, for every non trivial functional dependency, the left hand part is a candidate key.

So, if you have a dependency A → B where both A and B are prime attributes, this dependency violates the Normal Form only if A is not a candidate key, but a part of some candidate key.

Note that in that case, the dependency does not violates the 3NF.