Proceeding of ICAPP05, May 15-19, 2005
KAERI has improved the subchannel analysis capability of the best-estimate system
code, MARS, in which the COBRA-TF code was adapted as the 3D thermal-hydraulics (T/H)
module. Then, the subchannel analysis feature in the MARS 3D module was combined to the
existing coupled “system T/H and 3D reactor kinetics” capability of MARS. These features allow
for realistic simulations of local departure from nucleate boiling (DNBR) behavior as well as
global system T/H behavior. Using the MARS code, a demonstrative, coupled analysis of the main
steam line break (MSLB) is carried out. The results of the calculations seem to be very reasonable
and realistic so that these can be used to analyze the conservatism in the conventional safety
analysis.
