Reactor Vessel Water Level

Reactor Vessel Water Level (RVWL) is the height of water in the reactor vessel. It is typically described in terms of inches above active fuel.

It is expected that the reactor vessel water level remains constant during operations. It tends toward decreasing due to steam production and it is compensated for by adding feed water.

Rapid changes in water level is indicative of problems or breaks in containment. If water level goes below active fuel then it will no longer moderate fuel temperatures and fuel damage becomes possible. There are automatic systems which react to low water level to add fluid or close possible lines which may be responsible for leakage.