국내 KBS-3 방식 고준위방사성폐기물 심층처분시설 방사선학적 안전성 평가대상 방사성핵종 목록 선정개념(안) 제언

Abstract

The transport calculation for a wide variety of radionuclides contained in high-levelradioactive waste, especially spent nuclear fuel, is computationally difficult, and input data collection forthis also take a considerable amount of time. Accordingly, considering limited resources, it is possibleto reduce the calculation time while minimizing impact on accuracy by including only radionuclidesimportant to calculation result through applying some criteria among potential radiation source termsthat may release into environment. In this paper, therefore, we reviewed and analyzed the screeningprocess performed to select radionuclides to be considered in the safety assessment for the KBS-3 typerepository in Sweden and Finland. In both countries, it was confirmed that a list of radionuclides wasselected by comprehensively considering screening criteria such as radioactivity inventory, half-life,radiotoxicity, risk quotient, and transport properties, and etc. A comparison of radionuclides includedin the radiological safety assessment in both countries suggests that most of nuclides are consideredin common, and a few nuclides considered only in one country are due to differences in decay chaintreatment or spent fuel types. As of now, since most of information on the disposal facility in Korea hasnot been determined, it is necessary to comprehensively model release and transport of all radionuclidesconsidered in Sweden and Finland when performing the radiological safety assessment. Based on theseresults, we derived the screening concept of selecting a list of radionuclides to be considered in theradiological safety assessment for the domestic KBS-3 type geological disposal facility, and this resultis expected to be used as technical basis for confirming conformity with the safety objective. In a moredetailed evaluation reflecting domestic characteristics in the future, it would be desirable to consider onlyradionuclides selected in accordance with the screening procedure. However, further research should beconducted to determine the quantitative limit for each criteria.