Indian Journal of Science and Technology

Abstract

Objectives: To study the transient response of a VVER-1200 based nuclear power plant parameters and safety systems during a Large-break Loss of Coolant Accident (LBLOCA) for two distinct cases; one in which SCRAM is initiated and the other one in which SCRAM is not initiated due to malfunction of the system. Method: Personal Computer Transient Analyzer (PCTRAN) has been used to obtain transient response of the plant for 300 seconds during these accidents. A break of 0.1 m2 size in the hot leg of the primary coolant circuit has been considered in this work. It has also been assumed that off-site AC power supply is completely cut-off for both cases. Findings: Results show that for Loss of Coolant Accident followed by SCRAM, core thermal power drops to only 5% of the normal operating power within 5seconds. The peak fuel and cladding temperature is recorded to be slightly higher than 1800o C and 610o C respectively, showing no failure for any of the two. Maximum pressures inside reactor core structure and reactor containment building are recorded to be 162 bar and 3.5 bar respectively, which are within design limits. However, for Loss of Coolant Accident with no SCRAM, core thermal power is recorded to be around 80% of the normal operating value after 300 seconds. Peak fuel and cladding temperatures are recorded to be around 2100o C and 650o C respectively, low enough to avoid failure. Maximum pressure inside reactor core structure is recorded to be 162 bar but pressure inside containment building has risen to around 13.5 bar after 300 seconds time. Applications: PCTRAN is one of the most reliable simulation tools for analyzing a nuclear facility. The results obtained from this study may be used as a reference for designing different components and safety systems of VVER-1200 based nuclear power plants so that the risk of a severe accident is minimized.

Keywords: Loss of Coolant Accident, Safety Systems, Transient Response, VVER-1200