Does having the Shield Master feat mean that the shield is indestructible?
The Shield Master feat (PHB, p. 170) says:
If you take the Attack action on your turn, you can use a bonus action to try to shove a creature within 5 feet of you with your shield.
If you aren't incapacitated, you can add your shield's AC bonus to any Dexterity saving throw you make against a spell or other harmful effect that targets only you.
If you are subjected to an effect that allows you to make a Dexterity saving throw to take only half damage, you can use your reaction to take no damage if you succeed on the saving throw, interposing your shield between yourself and the source of the effect.
The last part says "use your reaction".
Last game session our paladin used his +1 shield to block a young dragon's 11d8 fire breath weapon, and prior to this, he did the same when confronted with an 12d6 explosive device of fire and shrapnel. How is his shield not riddled with holes from the explosive, and how is it not a melted slag of metal after the dragon's fire breath? Yes he made the saves, but shouldn't placing the shield directly in line of harm's way to protect him also heavily damage the shield if not destroy it?
The feat just says the PC doesn't take damage, but does not account for shield's condition after. Is a shield indestructible with the feat?