Material withdrawal apparatus, methods, and systems of regulating material inventory in one or more units are provided. A material withdrawal apparatus includes a heat exchanger and transport medium junction configured to provide transport medium to transport the withdrawn material from the unit to the heat exchanger. Another material withdrawal apparatus includes a heat exchanger and shock coolant junction configured to provide shock coolant to the material withdrawn from the unit. Another material withdrawal apparatus includes a heat exchanger, shock coolant junction, and transport medium junction. Another embodiment of a material withdrawal apparatus includes a vessel and shock coolant junction. Another material withdrawal apparatus includes a vessel and transport medium junction. The vessel includes a wall, liner with heat insulating refractory material, fill port, and a discharge port. Other embodiments provide methods of withdrawing or regulating material in a unit and systems coupled to a material withdrawal apparatus.