Structural Monitoring and Response Analysis of Prestressed Concrete Primary Containment of a Nuclear Power Plant

Abstract

Before commissioning, Pressurised Heavy Water Reactor (PHWR) containments are tested for their integrity at proof pressure and Loss-of-Coolant Accident (LOCA) pressure. During operation, as per the current practice for Indian PHWR containments, in-service Integrated Leakage Rate Test (ILRT) is done once in two years at about one third of LOCA based test pressure. Kaiga Generating Station unit-2 (KGS-2) has been in operation for more than 11 years. For the first time, a periodic ILRT at LOCA pressure (0.86 kg/cm2 (g)) was conducted at KGS-2. During this ILRT, structural monitoring of pre-stressed concrete primary containment was carried out. The deflection and strains at critical locations in the IC were recorded during ILRT mainly to compare the same with the values obtained from analytical study and with those observed during the first ILRT. The strain and deflection measurements were taken using vibrating wire strain gauges (VWSG) and high precision dial gauges respectively connected to data-logger. This technical paper highlights the structural behaviour of KGS-2 primary containment after 11 years of operation.