4.220. Appropriate instrumentation should be incorporated inside the containment for conducting the periodic leak tests. This should include instru­mentation for monitoring pressures, temperatures, humidity and flow rates. For steel containments, the temperature of the steel should also be measured. The number and the locations of instruments should be specified by the designer in accordance with the environmental conditions to be expected. Guidance on leak rate testing is given in Section 5.

4.221. Means for monitoring major leaks (e. g. by assessing the mass of the containment atmosphere by the use of devices for measuring pressure and temperature) should be incorporated to detect any major openings in the containment boundary caused by equipment failure or operator error. Guidance on monitoring for major leaks is given in para. 5.21.

4.222. Any containment leaks that are not collected in a building equipped with filtration devices, so-called direct leaks, should be carefully monitored to ensure that any leakage directly to the atmosphere would be detected.