Evaluation on licensability of KNGR system design

In this study, the design characteristics of KNGR and methodology of DBA analysis are reviewed, and CEFLASH code which used to design the system of nuclear plant was also investigated. From the result of these reviews, it revealed that there is no problem for the application of the evaluation model in CEFLASH code. However, fir the reflood period, the more reviews on ECC bypass and condensation phenomena are required. From the results of the analysis and experiment, the safety regulation for the DVI is dominated by the geometrical configurations, rather than the physical condition of the system. The fast neutron fluence at the Reactor Pressure Vessel(RPV) of KNGR designed for 60 years of lifetime was calculated by Monte Carlo simulations for reactor pressure vessel integrity assessment. KNGR core geometry was modeled on a three-dimensional. In the full-scope Monte Carlo method, the maximum fast neutron flux at inner vessel beltline was estimated as 2.738 X 1010 neutrons/cm2·sec. In the ROCS+MCNP4B calculation, the maximum flux of 2.769 X 1010 neutrons/com2·sec at the RPV was obtained by tallying neutrons crossing the inner surface of the RPV. The lifetime of KNGR was estimated on the basis of conservative end of life fluence limit value of the ABB-CE systme 80+. Approximately, 72 Effective Full Power Years(EFPYs), equivalent to 90 reactor years, of lifetime was expected in the full-scope Monte Carlo calculation. In the ROCS+MCNP4B calculation, the KNGR lifetime was expected as 71 EFPYs, equivalent to 88 reactor years