KBS-3 방식 고준위방폐물 심층처분장 FEP 분석을 통한 국내 사용후핵연료심층처분시설 방사선학적 안전성 평가용 지권영역 주요 프로세스 항목 및상대적 중요도 도출

Abstract

The deep geological repository of high-level radioactive waste shall be designed to meetthe safety objective set in the form of radiation dose or corresponding risk to protect human and theenvironment from radiation exposure. Engineering feasibility and conformity with the safety objectiveof the facility conceptual design can be demonstrated by comparing the assessment result using thecomputational model for scenario(s) describing the radionuclide release and transport from repositoryto biosphere system. In this study, as the preliminary study for developing the high-level radioactivewaste disposal facility in Korea, we reviewed and analyzed the entire list of FEPs and how to handleeach FEP from a general point of view, which are selected for the geosphere region in the radiologicalsafety assessment performed for the license application of the KBS-3 type deep geological repository inFinland and Sweden. In Finland, five FEPs (i.e., stress redistribution, creep, stress redistribution, erosionand sedimentation in fractures, methane hydrate formation, and salt exclusion) were excluded or ignoredin the radionuclide release and transport assessment. And, in Sweden, six FEPs (i.e., creep, surfaceweathering and erosion, erosion/sedimentation in fractures, methane hydrate formation, radiationeffects (rock and grout), and earth current) were not considered for all time frames and earthquake outof a total of 25 FEPs for the geosphere. Based on these results, an FEP list (draft) for the geosphere wasderived, and the relative importance of each item was evaluated for conducting the radiological safetyassessment of the domestic deep geological disposal facility. Since most of information on the disposalfacility in Korea has not been determined as of now, it is judged that all FEP items presented in Table 3should be considered for the radiological safety assessment, and the relative importance derived fromthis study can be used in determining whether to apply each item in the future.