Since the September 11 terrorist attacks in the United States, concerns about intentional aircraft crashes into nationally critical facilities have soared in countries around the world. The United States government advised nuclear utilities to strengthen the security of nuclear power plants against aircraft crashes and stipulated aircraft crash assessment for new nuclear facilities. Interest in military missile attacks on nuclear facilities has grown after Russia attacked Ukraine’s Zaporizhzhia nuclear power plant, where spent nuclear power dry storage facility is operated. Spent nuclear fuel dry storage facilities in nuclear power plant sites should also strengthen security in preparation for such aircraft crashes. Most, but not all, spent nuclear fuel dry storage facilities in Europe, Japan and Canada are operated within buildings, while the United States and Korea operate dry storage facilities outdoors. Since all of Korea’s dry storage systems are concrete structures vulnerable to crash loads and are exposed to the outside, it is more necessary to prepare for aircraft crash terrorist attacks due to the Korea’s military situation. Residents near nuclear power plants are also demanding assessment and protective measures against such aircraft crashes. However, nuclear power plants, including spent nuclear fuel dry storage facilities, are strong structures and have very high security, so they are unlikely to be selected as targets of terrorism, and spent nuclear fuel dry storage systems are so small that aircraft cannot hit them accurately. Collected opinions on the assessment of aircraft crash accidents at spent nuclear fuel dry storage facilities in nuclear power plant sites were reviewed. In addition, the current laws and regulatory requirements related to strengthening the security of new and existing nuclear power plants against intentional aircraft crashes are summarized. Such strengthening of security can not only ensure the safety of on-site spent nuclear fuel dry storage facilities, but also contribute to the continuous operation of nuclear power plants by increasing resident acceptance.

In Korea, the construction of dry storage facilities for spent nuclear fuel is being promoted through the 2nd basic plan for high-level radioactive waste management. When operating dry storage facilities, exposure dose assessment for workers should be performed, and for this, exposure scenarios based on work procedures should be derived prior. However, the dry storage method has not yet been sufficiently established in Korea, so the work procedure has not been established. Therefore, research is needed to apply it domestically based on the analysis of spent nuclear fuel management methods in major overseas leading countries. In this study, the procedure for receiving and storing spent nuclear fuel in a concrete overpack-based storage facility was analyzed. Among the various spent nuclear fuel management systems, the metal overpack-based HI-STAR 100 system and the concrete overpackbased HI-STORM 100 system are quite common methods in the United States. Therefore, in this study, work procedures were analyzed based on each final safety analysis report. First, the HI-STAR 100 overpack enters the facility and is placed in the transfer area. Remove the impact limiter of the overpack and install the alignment device on the top of the overpack. Place the HI-TRAC, an on-site transfer device, on top of the alignment unit and remove the lids of the two devices to insert the canister into the HI-TRAC. When the canister transfer is complete, reseat the lid to seal it, and disconnect the HI-TRAC from the HI-STAR 100. Raise the canister-loaded HI-TRAC over the alignment device on the top of the HI-STORM 100 overpack and remove the lids of the two devices that are in contact. Insert the canister into the HI-STORM 100 and reseat the lid. The HI-STORM 100 loaded with spent nuclear fuel is transferred to the designated storage area. In this study, the procedure for receiving and storing spent nuclear fuel in a concrete overpack-based storage facility was analyzed. The main procedure was the transfer of canisters between overpacks, and it was confirmed that HI-TRAC was used in the work procedure. The results of this study can be used as basic data for evaluating the exposure dose of operating workers for the construction of dry storage facilities in Korea.

Some Spent Fuel Pools (SFPs) will be full of Spent Nuclear Fuels (SNFs) within several years. Because of this reason, building interim storage facilities or permanent disposal facilities should be considered. These storage facilities are divided into wet storage facilities and dry storage facilities. Wet storage facility is a method of storing SNF in SFP to cool decay heat and shielding radiation, and dry storage facility is a method of storing SNF in a cask and placing on the ground or storage building. However, wet storage facilities have disadvantages in that operating costs are higher than that of dry storage facilities, and additional capacity expansion is difficult. Dry storage facilities have relatively low operating costs and are relatively easy to increase capacity when additional SNFs need to be stored. For this reason, since the 1990s, the number of cases of applying dry storage facilities has been increasing even abroad. Dry storage facilities are divided into indoor storage facilities and outdoor storage facilities, and outdoor storage facilities are mostly used to take advantage of dry storage facilities. In the case of outdoor storage facilities, the cask in which SNFs are stored is placed on a designed concrete pad. During this storage, the boring heat generated by SNFs cools into natural convection and the cask shields the radiation that SNFs generates. However, if an accident such as an earthquake occurs and the cask overturns during storage, there may be a risk of radiation leakage. Such a tip-over accident may be caused by the cask slipping due to the vibration of an earthquake, or by not supporting the cask properly due to a problem in the concrete pad. Therefore, in the case of outdoor dry storage facilities, it is necessary to evaluate the seismic safety of concrete pads. In this paper, various soil conditions were applied in the seismic analysis. Soil conditions were classified according to the shear wave velocity, and the shear wave velocity was classified according to the ground classification criteria according to the general seismic design (KDS 17 10 00). The concrete pad was designed with a size that 8 casks can be arranged at regular intervals, and 11# reinforcing bars were used for the design of the internal reinforcement of the concrete pad according to literature research. The cask was designed as a rigid body to shorten the analysis time. The soil to which the elastic model was applied was designed under the concrete pad, and infinite elements were applied to the sides and bottom of the soil. The effect on the concrete pad and cask by applying a seismic wave conforming to RG 1.60 to the bottom of the soil was analyzed with a finite element model.