Flooding (nuclear reactor core)

As this phenomenon proceeds, annular flow running counter-current begins as liquid water is inserted into the system.

Then if conditions are correct, the frictional force at the gas-liquid interface begins to reverse the flow of the liquid.

Given a high enough flow rate of steam, reversal of the ECCS-injected liquid water occurs.

The core barrel and the reactor vessel wall form a cylindrical shell that is referred to as the downcomer.

[3] Flooding as a fluid flow phenomenon should be distinguished from the act of filling the core with coolant ("flooding of the reactor core"), as the fluid flow phenomenon occurs during the filling process.

Picture depicts reversal of counter-current flow to concurrent flow, which may be seen during flooding of a nuclear reactor core. (A) Counter-current annular flow (B) Point of flow reversal (C) Concurrent slug flow (or other flow)