user: Question: What is the Tonnage that has builder AG Vulcan, and the original operator NDL, and the ship, Prinzess Irene?
Columns: ['Ship', 'Tonnage', 'Builder', 'Original Operator', 'Fate']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Friedrich der Grosse', 'GT', 'AG Vulcan', 'NDL', '01922 Sunk after fire, 1922']
SQL:

assistant: SELECT "Tonnage" FROM "Table" WHERE "Builder" = 'AG Vulcan' AND "Original Operator" = 'NDL' AND "Ship" = 'Prinzess Irene';