A.9. Storage tanks and the drain sump of each safety system as well as the condensate collector of each air cooler should be provided with a water level indicator.

Balance of fluid flow

A.10. The periodic calculation of a mass balance can show quantitatively the amount of identified and/or unidentified small leaks in a given volume. For the calculation of a mass balance, fluid flows should be measured to establish the mass balances in the different systems. Measurements of temperature, pressure and humidity are combined to monitor for leaks from the containment in most operational states by enabling the periodic calculation of the mass of the containment atmosphere.