I was just there on Monday. They had contractors pouring in preparing for this quick maintenance outage. If I recall they said the leak occured somewhere between the steam reheaters/moisture seperators and U1's turbine generator. Don't take my word for it though.
Edit: I was under the impression there was a steam leak. I dont think they mentioned anything to me about a hydrogen leak but from the looks of it and from what I overheard, they had plans to take care of a few things while offline.
