DEPCO-MULTI, Subcooled Decompression in PWR Primary System LOCA

1 - Nature of physical problem solved: DEPCO-MULTI is used to analyze the subcooled decompression in a multiple pipe network such as a PWR primary coolant system after an instantaneous pipe break. 2 - Method of solution: The unsteady one dimensional mass, momentum and energy conservation laws are converted to a set of compatibility conditions and characteristic directions equivalent to them. After the simplification of the compatibility conditions, they are numerically integrated by the explicit formula. 3 - Restrictions on the complexity of the problem: (1) Maximum number of different thermodynamic initial conditions: 5; (2) Maximum output points of: - pressure history: 5; - pressure difference history: 3; - flow velocity history: 1. (3) The assumptions of thermal equilibrium, no buoyancy effect, no heat transfer and one-dimensional analysis are used