(A) study on the methodology of integrated safety assessment on low and intermediate level waste (LILW) managed in temporary storage facility at NPP

Abstract

Since 1978, the KHNP has been operating 20 NPPs (16 PWRs and 4 CANDUs) and generating about 67,000 drums (200 L) of LILW (as of December 31, 2005), which have been stored in the temporary storage facility (TSF) at each NPP due to the absence of a repository for the disposal of LILW. Therefore, the period of temporary storage of LILW is so long compared to other countries. Furthermore, the details with respect to the safety anlaysis on the TSF have not been considered in PSAR and FSAR. Especially, the risk assessment on the TSF has scarcely been conducted as opposed to many researches on the disposal of LILW. Since 2003, however, the IAEA has been recognized on the imporatance of predispoal management of LILW. And then, the regulatory frame of U.S. NRC was being shifted to risk-based regulation from the deterministic apporoach. Therefore, most of radioactive wastes including the LILW will be managed in terms of the risk-based graded apporaoch to future regulation system called RIR (risk informed regulation). If the radioactive wastes do not quantitatively deal with the risk-based reagulation, the radiological risk on some of radioactive wastes might be overestimated or underestimated regardless of the degree of the risk. According to a consequence of these situations, the numbers of the researches on the predisposal management of LILW have been required for the preparation on new regulatory frame. In this study, the main objective of this study is to establish the methodology of integrated safety assessment on LILW managed in the TSF at NPP, and to develop the integrated safety assessment code for routine operating condition and for for accident analysis on LILW managed in the TSF. In order to establish the methodology of integrated safety assessment on LILW managed in the TSF at NPP, three main parameters were considered: risk-based accident scenarios, radionuclide inventory, and atmospheric dispersion factor ($\It{x/Q}$). Arbitrary accidents related to LILW ...