I just accidently locked myself inside Vault 22, Here's the story.

I went inside when I was lvl 5, cleared it out to get the Giant Mantis Eggs for the quest Bleed Me Dry for The Thorn. I later went back for the mission There Stands The Grass but when I got to the point that I had to detonate the gas I did not have access to the grenades (Having looted them earlier in the game) my only gun was a Cowboy Repeater. I had cleared the lvls of all usable weapons the first time and now am locked in due to the infection lockdown in effect. I can only trigger the gas by shooting inside the cloud which results in death. I think they should patch it so that when she tells you to blow up the gas she automatically gives you 3 grenades, adding them directly to your inventory.

I know this isn't a big thing but I lost 14 hours just by getting locked inside due to this. No I didn't have an earlier save. Has anyone else had this happen? or something near the same?

Try reducing the difficulty setting. I have no idea if it works but it might be worth a shot.