If I'm correct ,and I'm probably not, 101 was supposed to remain indefinately, not to ever be opened.
"The purpose of Vault 101 in the Vault Experiment was not only to test the results of indefinite isolation (designed never to reopen), but to also test the role of the Overseer. The second Overseer decided to let a select few of the adults in on the secret to help keep it from the children, and over the years each subsequent generation had more and more residents who knew the truth about the Vault. In addition, the Overseer was able to communicate with, and even visit, the outside world by using the secret tunnel in the Overseer's office[1]. However, for all other intents and purposes, the vault's residents were sealed in: "It is here you were born, it is here you will die." With the escape of the Lone Wanderer, the experiment enters a new phase. "
Quoted from Fallout Vault (Fallout Wiki)