This Old House

Bring Scrap Metal to Help Fix Up The Underworld is a minor quest.

Speak with Winthrop in the Underworld at the Museum of History along the Capital Mall to unlock the option to bring him up to 5 scrap metals at once in trade for Stimpacks or RadAways. This quest is very similar to Fix broken pipes around Megaton.

This quest can be side-stepped if strength is high enough by threatening Winthrop and forcing him to give you all the Stimpacks and RadAways he has.