Effect of SIT-FD Modeling on Severe Accident Analysis Using MAAP5

A passive Fluidic Device(FD) inside the conventional Safety Injection Tank(SIT) was introduced as one of the new Engineered Safety Features(ESFs) in the APR1400 plants. To investigate the effect of FD modeling for Large Break(LB) LOCA during severe accident, the severe accident analysis code most widely used by nuclear industries, MAAP5, was used. The modeling was done by adjusting the loss coefficient in the accumulator model of MAAP5. The SIT-FD flow rate obtained and the several results of LBLOCA without safety injection case are presented. The behavior of SIT-FD was modeled using accumulator model of MAAP5 by adjusting the loss coefficient to simulate the LBLOCA without SI during severe accidents in APR1400 plant. The results show that the time of vessel failure was delayed by about 10 minutes and the mass of Hydrogen generated was reduced by 29 Kg. It demonstrates that the proper modeling of the ESFs in APR1400 plant is necessary to get better insight for severe accident analysis.