In the wake of the Fukushima NPP accident, research on the safety evaluation of spent fuel storage facilities for natural disasters such as earthquakes and tsunamis has been continuously conducted, but research on the protection integrity of spent fuel storage facilities is insufficient in terms of physical protection. In this study, accident scenarios that may occur structurally and thermally for spent fuel storage facilities were investigated and safety assessment cases for such scenarios were analyzed. Major domestic and international institutions and research institutes such as IAEA, NEA, and NRC provide 13 accident scenario types for Spent Fuel Pool, including loss-of-coolant accidents, aircraft collisions, fires, earthquakes. And 10 accident scenario types for Dry Storage Cask System, including transportation cask drop accidents, aircraft collisions, earthquakes. In the case of Spent Fuel Pool, the impact of the cooling function loss accident scenario was mainly evaluated through empirical experiments, and simulations were performed on the dropping of spent nuclear fuel assembly using simulation codes such as ABAQUS. For Dry Storage Cask System, accident scenarios involving structural behavior, such as degradation and fracture, and experimental and structural accident analyses were performed for storage cask drop and aircraft collision accidents. To evaluate the safety of storage container drop accidents, an empirical test on the container was conducted and the simulation was conducted using the limited element analysis software. Among the accident scenarios for spent fuel storage facilities, aircraft and missile collisions, fires, and explosions are representative accidents that can be caused by malicious external threats. In terms of physical protection, it is necessary to analyze various accident scenarios that may occur due to malicious external threats. Additionally, through the analysis of design basis threats and the protection level of nuclear facilities, it is necessary to derive the probability of aircraft and missile collision and the threat success probability of fire and explosion, and to perform protection integrity evaluation studies, such as for the walls and structures, for spent fuel storage facilities considering safety evaluation methods when a terrorist attack occurs with the derived probability.

현행 해양유출사고 시나리오는 예상가능한 최대 유출사고를 근거로 하여 시나리오가 작성되었다. 하지만, 최대유출사고 시나리오 와 유사한 규모의 사고는 실제 거의 일어나지 않았는데, 이러한 시나리오를 바탕으로 한 훈련이나 대응장비배치 등은 대비 측면에서 본다면 낮은 비용효율을 가지는 것으로 볼 수 있다. 현행의 시나리오는 활용성과 현장도가 높은 시나리오 구현을 통한 실전에 가까운 형태로 구성될 필요가 있고, 활용 목적에 적합하도록 설계될 필요가 있다. 따라서, 본 연구에서는 과거 사고사례를 바탕으로 한 시나리오 작성을 위해 기 개 발된 HNS 사고 표준코드를 활용하여 현행 시나리오를 대체할 수 있는 대체 사고 시나리오(Alternative Accident Scenario)를 구성하고자 하 였다. 시나리오는 HNS 사고 표준코드를 모듈화하여 최대 빈도 시나리오, 최대 피해 시나리오, 최대 취약성 시나리오 3가지로 구분하여 작성 하였다. 이런 과정을 거쳐 제시된 각 시나리오별로 제시된 사고발생 상황은 실제 사고와 유사한 형태를 나타내므로 현장에서의 합목적적인 활용이 가능할 것으로 판단된다.

This study was conducted to build an emergency action plan (EAP) for cable-supported bridges in South Korea. First, accidents happened on Cable-supported bridges were investigated and categorized based on the types. Second, accident scenarios were built-up regarding the types. Two bridges were selected for planning the emergency action following the accident scenarios. The emergency action plan established in this study could be used for the management of cable-supported bridges in the future.