Can't open iPhoto since upgrading to Mavericks

I have a MacPro now running OS 10.9.2 which has been backed up regularly to an external drive using Time Machine. I've been using iPhoto for years, have thousands of photos in the library (all but the most recent saved to an external drive as a secondary backup).

When I tried to open iPhoto for the 1st time after the upgrade I gor an error message that says "The iPhoto Library is locked, on a locked disk, or you do not have permission to make changes to it. iPhoto can try to repair the permissions."

I click on repair, get lots of spinning then get the message, "The iPhoto Library is locked, on a locked disk, or you do not have permission to make changes to it." I tried to find the library on the machine using a variety of search requests. "iPhoto library", "library", bring up nothing, spotlight simply finds the application.

What gives, and more importantly, what can I do?

Thanks in advance,

Tom