A.1. This appendix provides recommendations for the measurement of parameters for the containment systems, to allow diagnosis by the operator of developing deviations from normal operation; in particular, to allow detection of releases of coolant or other radioactive fluids within the containment. The operator can evaluate these parameters and take corrective actions at an early stage to prevent a minor failure from developing into a serious plant failure or even an accident condition. In addition, these measured parameters are used as inputs to the automatic containment isolation system and other reactor protection systems.

PHYSICAL PARAMETERS

A.2. Typical conditions causing deviations from normal operation include:

— Release of high temperature fluids,

— Leakage of high pressure fluids,

— Presence of radioactive gases or liquids,

— Fire,

— Mechanical failure of components.

A.3. The physical parameters that should be monitored within the containment differ in different reactor systems. Parameters that are typically monitored include:

— The temperatures of the containment atmosphere and of the fluid drains,

— The pressure in the containment building,

— The humidity in the containment building,

— The hydrogen concentration in the containment building,

— Water levels in the drains,

— Rates of fluid flow,

— Radiation levels and activity of airborne radioactive material,

— Radiochemical analysis of drain water,

— Visible abnormalities,

— Noise and vibrations,

— Fire.

A.4. The measurement sensitivities necessary to detect a developing deviation should be estimated by appropriate analytical methods.

Temperatures of the containment atmosphere and fluid drains

A.5. Both atmospheric temperatures and the temperatures of fluid drains should be measured.

(a) Atmospheric temperatures. A sufficient number of temperature sensors should be installed to measure the atmospheric temperature distribution throughout the containment building. In addition, measurements of the fluid temperatures of the containment air coolers may be used to estimate the temperature of the atmosphere. The data display should present the temperature distribution and the local trends in atmospheric temperatures and fluid temperatures.

(b) Drain temperatures. The temperatures should be measured in selected fluid drains (system drains and floor drains) in order to determine whether there is in-containment leakage from any steam system or pressurized water system. These temperature measurements should be recorded to show trends.