Construction of tunnels in a deep crystalline host rock for a potential High-Level Radioactive Waste(HLW) repository inevitably generates an excavation disturbed zone (EDZ). There have been a series of debates on whether a permeability in an EDZ increases or not and what would be the maximum depth of an EDZ. Recent studies show mixed opinions on permeability. However, there has been an international consensus on the thickness of an EDZ; 30 cm for TBM and 1 meter for controlled blast. One of the impacts of an EDZ is on determining the distance between adjacent deposition holes. The void gap by the excavation hinders relaxation of temperature profiles so that the current Korean reference designing distance between holes should be stretched out more to keep the maximum temperature in a buffer region below 100 degrees Celsius. The other impact of an EDZ is on the long-term post closure radiological safety. To estimate the impact, the reference scenario, the well scenario, is chosen. Released nuclides diffuse through a bentonite buffer region experiencing strong sorption and reach a fracture surrounded by a porous medium. Inside a fractured porous region, radionuclides migrate by advection and dispersion with matrix diffusion into a porous medium. Finally, they reach a well assumed to be a source of potable water for local residents. The annual individual dose is assessed on this well scenario to find out the significance of an EDZ. A profound sensitivity study was performed, but all results show that the impact is negligible. Even though the role of an EDZ turns out to be limited on overall safety assessment, still it is worthwhile to study the chemical role of an EDZ, such as a potential source for natural colloids, potential sealing of an open fracture by fine clay particles generated by the process of an EDZ, and alteration of a sorption mechanism by an EDZ in the future.
목차
Abstract I. Introduction II. Role of EDZ III. Effect of EDZ on Post Closure RadiologicalSafety in a Potential HLW Repository 1. Construction of Well Scenario 2. Input Data for Sensitivity Study 3. Numerical Results 4. Conclusions IV. Other Issue V. Conclusions Acknowledgements References
키워드
EDZ(Excavation Disturbed Zone)High-Level Radioactive Waste DisposalTotal System Performance AssessmentWell Scenario
한국방사성폐기물학회는 국내 방사성폐기물 관리 분야 산ㆍ학ㆍ연 관계자들의 학술단체로 학술연구발표회 및 강연회 개최, 학술간행물 발간 등의 학술 진흥사업, 방사성폐기물에 관한 국제교류 및 협력 증진사업, 방사성폐기물에 관한 위탁연구 자문 및 평가사업 수행 등으로 국내 방사성폐기물 관리 분야 전반의 내부 역량 강화와 경쟁력 확보를 도모하고자 한다. 더 나아가 국가사회 발전에 미치는 중요성을 인식하는 계기를 만들고자 한다. 또한 이러한 활동을 통하여 국가경제 발전과 국민건강에 일조할 수 있도록 하며, 궁극적으로는 한국방사성폐기물학회가 세계 속의 학술단체로의 발전해 나가는 것을 목표로 한다.
간행물
간행물명
방사성폐기물학회지 [Journal of Nuclear Fuel Cycle and Waste Technology (JNFCWT)]