Analysis of system decontamination effectiveness by development of decontamination factor evaluation program

This study compares how the change in decontamination scope affects the total decontamination factor (DF) in system decontamination of Kori Unit 1 (Kori-1), by development of decontamination factor evaluation program (DFEP). The DFEP calculates the total DF from initial activity inventory and its measurement date of each part in whole scope of decontamination, decontamination date and number of decontamination cycles, and DF of each cycle in each part. For every cycle, DF of each part is driven by DF of each cycle in whole system, and DF of each part in whole cycles, both from overseas full system decontamination (FSD) cases. By the analysis of DFEP, total DF cannot reach the Kori-1 target DF, 30, in case of excluding both SGs. In the case of excluding only 1 SG, total DF can be over 30 if additional 2 more cycles of decontamination with excluding 1 SG are done after 2-cycle FSD. Comparing which of the SG is excluded, the total DF is higher in the case of excluding the SG connected to pressurizer side.