If you were already in prison, you would be somewhat more likely to survive the initial outbreak because not that many people enter or leave the prison, at least compared to a place of business. read more
If the prison were full of the normal people (prisoners, guards, staff) when the outbreak hit it would be a death trap for a lot of people. FYI I am going with the description of the prison in the walking dead as I have never seen one in person. But the prison itself would make a great defensive home against zombies. read more