Integrity surveillances of operational safety and the leak test Type B of the Steel containment due to condition of design basis accident in NPP

The objective of the integrated leak rate test (ILRT) is to measure the containment system overall integrated leakage rate under conditions representing design basis loss-of-coolant accident peak pressure to ensure that the integrity of the containment structure is maintained during its service life. The overall integrated leakage rate means the total leakage through all tested leakage paths, including containment welds, valves, fittings, and components that penetrate the containment system. It is need to carry out local leak test of all potential leak pats before first ILRT. These local leak test (type B test) are usually carried out at full length of scope and general suppliers are responsible for their good results. Besides these test it is recommended for NPP operator to create group of specialist for local leak rate test for carry out so-called super checks.