Now I Get It: 'Doomsday' food vault gets an upgrade

On Friday, the Norwegian government announced the Svalbard Global Seed Vault is getting a $13 million upgrade after an unexpected thaw of permafrost in late 2016 caused water to seep into the vault. The facility stores and protects seeds for about a million of the world's crops and plants and is built to withstand disasters ranging from nuclear war to global warming. What are the other significant features of the "doomsday vault"?