In recent times, drone technology has been rapidly advancing and becoming increasingly popular. Furthermore, there has been an increase in the number of crimes and terrorism cases targeting national facilities using drones. This study aims to categorize the types of drone threats that could pose future risks to nuclear power plants. For this study, we are investigating domestic and foreign drone terrorism cases and identifying the specifications of drones used. It has been confirmed that products from Chinese DJI companies have frequently appeared as commercial drones used in terrorism. This suggests that conversion of general commercial drones into weapons can be effectively utilized for terrorist activities. There is an elevated risk of terrorism involving multiple small drones. Nuclear power plants must also devise protective measures against a large influx of drones. Additionally, it is predicted that North Korea is developing drones equipped with return technology through GPS-based autonomous mission flights. North Korea’s drones are presumed to have been converted from Chinese drones (SKY-09P, UV10CAM, etc.). According to the analysis based on the weight and size of the drone, drones weighting less than 150 kg and wingspan of less than 3 m are used for terrorism. To effectively detect drones, it is necessary to implement measures such as integrating and deploying various equipment to compensate for equipment limitations (radio waves, radar, video, sound, etc.). In the case of long-distance flight, a number of fixed-wing drones capable of autonomous mission flight and long-distance flight were used. North Korea’s drones use GPS-based autonomous mission flights, so it is necessary to prepare drones that do not transmit RF signals to detect them. Both RF signal detection and GPS jamming should be carried out, with GPS jamming taking precedence, even in the case of fixedwing drones. The results of this study could contribute to enhancing the level of physical protection of nuclear power plants.

In response to the increase in international terrorism threats and demands for terrorism prevention and response activities, the Act on Counter-Terrorism for the Protection of Citizens and Public Security was enacted in 2016, and the need for research to strengthen protection against explosive threats was raised. In the same manner, the Design Basis Threats, which become the standard for the design and evaluation of physical protection systems for nuclear facilities, have been developed and it includes explosive threats. However, the regulatory standards for physical barriers against explosive threats are still not established. Therefore, it is first required to set up a performance database of physical barriers subject to blast loading in order to prepare the regulatory standards. In this study, the pressure with the trinitrotoluene (TNT) charge weights of 0.5-2 kg as a function of time was calculated using Ansys Autodyn software by assuming that the TNT is used for malicious purposes and is attached to a reinforced concrete (RC) corridor wall. The shape of the corridor was the 3×3×6 m cuboid with a rectangular hole of 1.78×1.78×6 m. The RC walls, which make up the corridor, contained the reinforcing bars with a spacing of 0.229 m and a diameter of 0.036 m. The spherical charge of a TNT was placed 0.2 m away from a RC wall in the middle of the corridor. To measure the reflected pressure after the internal explosion with a TNT, three pressure gauges were installed on the three sides of the RC walls in the middle of the corridor, respectively. The results showed that the peak reflected pressure on a RC wall with the standoff distance of 0.2 m was about ten times higher than the opposite RC wall with the standoff distance of 1.58 m in the same condition of TNT charge weight. Thus, it was verified that blast loads are highly affected by standoff distance. It seems that preventing the explosive detonation close to a physical barrier is strategically important to maintain the integrity of the physical barrier.

In order to enter a nuclear power plant, access approval is required in advance, and biometric information such as fingerprints of visitors must be registered when issuing a key card, and only those certified through biometric equipment can enter the nuclear facilities (Protected area II). Fingerprint recognizers and facial recognizers are installed and operated in domestic nuclear facilities for access control. Domestic nuclear facilities establish and implement a protection system in accordance with physical protection requirements under the “Act on Physical Protection and Radiological Emergency” and “Physical Protection Regulations” of each nuclear facility. Detailed implementation standards are specified in Regulation Standard (RS) documents established and distributed by KINAC. Biometrics are mentioned in a KINAC RS-104 (Access Control) document. In this study, it was analyzed what points should be considered in order to prepare for performance tests and establish plans for biometric devices. In order for the results of performance evaluation of biometric devices to obtain high reliability and to be applied to nuclear facilities in the future, standardized performance evaluation targets, procedures, standards, and environments must be created. In order to collect samples such as fingerprints for performance evaluation, the size roll of the sample shall be determined, and the appropriateness of the sample size shall be evaluated in consideration of reliability and error range. In addition, the analysis results for the characteristics (gender, age, etc.) of the sample should be presented. When collecting samples, conflicts with other laws such as personal information protection should be considered, and the reliability of the performance test result data should be analyzed and presented. Quality evaluation should also be performed on forged biometric information data such as silicon fingerprints. In addition, when establishing a performance evaluation plan, a systematic evaluation procedure should be established by referring to domestic and foreign certification and evaluation systems such as the Korea Internet & security Agency (KISA). In order to improve the completeness of the access control system using the biometrics of nuclear facilities, it is necessary to test the performance of biometric devices and to install and operate only devices that have the ability to defend against counterfeit technology. In this study, it was analyzed what points should be considered in order to prepare for performance tests and establish plans for biometric devices.

As drone technology and industry develop around the world, the use of drones are increasing in number and expanding to different fields. On the other hand, illegal flight and terrorist incidents using drones are also increasing day by day. In Korea, it is reflected in the “Design Basis Threat (DBT)”, which is the standard for designing and evaluating the physical protection system of nuclear power plants in accordance with the “Act on Physical Protection and Radiological Emergency”, that nuclear power plants continue to establish physical protection against drone threats. A total of 141 drone attacks or incidents have occurred around the world since 2015. Cases related to the Russian-Ukraine war, in which so many cases occurred, were excluded. There were 112 cases (79%) of terrorism or suspected terrorism using a single drone. There were 4 cases of terrorism using more than 5 drones, and a total of 20 drones were used to attack an oil facility in Yemen (2019). By region, a total of 111 incidents occurred in Middle East & North Africa. By country, there were 49 cases in Iraq, 35 cases in Saudi Arabia, and 8 cases in Syria. Among major countries, three cases occured in Korea, five in the United States, two in England, Canada, and Italy, and one in Japan and France. Since 2021, there have been 15 drone attacks. Multiple drones were used in attacks targeting military or large-scale Important National Facilities such as the Saudi oil refinery, Indian Kashmir air base, and reconnaissance of Iranian Natanz nuclear and surrounding military facilities. Also in 89% of the cases, the drones were loaded with explosives in order to cause large-scale damage. Accordingly, nuclear power plants, which are important national facilities, need to establish a system that can detect and respond to multiple drones. Furthermore, additional protective measures are needed for areas that are expected to be severely damaged which can be established by evaluating the impact of explosives on major points in the plant. In additionthere is a high possibility of terrorism by organizations aiming for national turmoil rather than individual terrorists. So it is important to identify signs of terrorism in advance and prepare through cooperation with related agencies.

For national security, approximately 500 facilities have been designated as national security facilities. It is divided into grades A, B, and C depending on the fields such as electrics, energy and public service. In 2016, KINAC developed and suggested the installation standards and evaluation indicators for security equipment for national security facilities and they have been utilized to evaluate and manage the facilities. In order to update them by reflecting the recent security trend of the facilities and new technology, KINAC have investigated and updated the installation standards and evaluation indicators for security equipment. As a part of developing installation standards and evaluation indicators for national security facilities project, we conducted survey to identify the status and capabilities of facilities: how the security system is well designed, which type of security equipment is utilized. According to the results, the passive infrared (PIR) sensor is commonly used for interior intrusion detection (not included in 2016 project). Therefore, we investigated the passive infrared sensor and provided its installation standards and evaluation indicators. PIR sensor detects the energy generated by the objects which is different as their temperatures. PIR sensors do not emit any energy like active infrared sensor, and do not measure the energy. Rather, PIRs measure variation in thermal radiation. PIR sensor detects thermal energy by sensing the change between a heat source and the background temperature. In this paper, the characteristics and features of PIR sensor were discussed. Considering them, the standards and indicators to install/evaluated the PIR sensors were also proposed. The results would support national security facility to design and evaluate their security system.

Nuclear power plants, like other national critical infrastructures, could be under the threat of terrorism or other malicious action. Thus, a nuclear power plant has a robust security system that includes security guards, sensors, barriers, access control systems, lights, and alarm stations with security procedures. However, an effective security system is hard to design because a chain is only as strong as its weakest link, and there could be a vulnerable hole even in the robust security system. Thus, an effective security system requires the evaluation of all possible scenarios. Evaluation software for security system effectiveness assists in systematically assessing all the possible attack scenarios. Many countries developed security effectiveness evaluation software. The first software was developed by the U.S. Sandia National Laboratories in the 1980s. Now there are several commercially available software packages with a function to simulate limited-scope combat between security guards and attacking enemies. However, academic communication is comparatively weak because it may contain sensitive information on the vulnerability of nuclear power plants. We developed original software called Tools for Evaluating Security Systems (TESS) to identify the most vulnerable path to the designated target and model the security systems of all South Korean nuclear power plants. We also used commercial security effectiveness evaluation software, AVERT, to model the same nuclear power plants. TESS was developed to verify the results of commercial security effectiveness evaluation software for the purpose of regulatory use. For the feasibility test, we compared the results of two software with those of force-on-force (FoF) exercises in nuclear power plants. According to the relevant Act, every nuclear power plant site should perform the FoF exercises every year. KINAC was in charge of evaluating the FoF exercise and used several of its results for the study. In the results, even in some differences in detail, the two software and FoF exercises showed qualitative similarity. Conclusively, evaluation software is a useful tool to design and/or assess the security systems of nuclear power plants. We modeled the security systems of all South Korean nuclear power plants, and compared the developed software, a commercial software and FoF exercises. The results showed qualitative similarity. We provided the results of evaluation to nuclear operators for the better security of nuclear power plants.

UAVs (Unmanned Aerial Vehicle) are a rising threat to national facilities due to their cheap price and accessibility. Incidents such as the terrorism attack in Saudi Arabia’s oil facilities and the paralysis of the airport system in England’s Gatwick airport shows the need for integrating CUAS (Counter- Unmanned Aerial Systems) in important national facilities. Recently efforts have been made to evaluate the technical performance of the CUAS. Especially SNL (Sandia National Laboratory) modified the methodology used for PPS (Physical Protection Systems) to develop a performance metrics for CUAS. The performance metrics can be used to effectively analyze the facilities capability of countering drone attacks in a probabilistic way. In this study, we managed to derive the safety boundary of a reference nuclear power plant model based on its current CUAS and protection capabilities with a simplified methodology. Based on the outermost boundary of the model, the time table of the UAS consist of 4 variables which are the assessment time, transmission time, neutralization time and the maximum vehicle velocity. Dividing the maximum velocity to the net time derived, we estimated the minimum sensing point of the CUAS which is the minimum safety boundary of the facility to safely manage the UAV attack. Two practice cases were evaluated with the methodology which is based on the UAV groups classified by the United States DOD (Department Of Defense) that matches the classification of the UAV in Korea. Each variable was assumed to fit the process of a realistic nuclear power plant. Using the variables, we calculated the minimum safety boundary of the facility. With the methodology introduced in this study, regulators and stakeholders can easily evaluate the capability of the facilities CUAS for a design basis UAV attack. Also it can be used as a simple tool to analyze the facilities vulnerability for specific UAV specifications and a guideline to check the protective procedures of the facility.

Nuclear power plants, which are important national facilities, require special attention against the threat of terrorism using various methods. Among the terrorist threats, as structural damage and human casualties due to explosions continue to occur, interest in the blast load is increasing. However, domestic nuclear power plants do not have sufficient design requirements for protection against the threat of explosives. To prepare for the threat of terrorism using explosives, it is necessary to evaluate the physical protection performance of nuclear power plants against blast load, and to use this to improve protection performance and establish regulatory standards. Most of the explosion-proof designs used abroad use the empirical chart presented by UFC 3-340- 02 (DoD 2008), which does not take into account the effect of near-field explosions. When explosions occur inside nuclear power plants, near-field explosions occur in most cases. In this study, it was assumed that explosives were installed in the corridor inside nuclear power plants. A spherical TNT was placed in the middle of the corridor floor to simulate near-field explosions, and the structure response according to the weight of the TNT was evaluated. The corridor was modeled with a reinforced concrete material and the LS-DYNA program was used for analysis. For the explosion model, the Arbitrary-Lagrangian-Eulerian (ALE) analysis technique applying the advantages of the Lagrangian and Eulerian methods were used. By analyzing the pressure history and the degree of deformation of the structure according to the explosion, the degree of threat caused by the explosion was analyzed. Based on the analysis of this study, physical barriers performance database (DB) using Modeling & Simulation (M&S) will be constructed by performing sensitive analysis such as representative structure shape setting, boundary conditions, material of structures, etc. The constructed DB is expected to be used to establish regulatory standards for the physical barriers of nuclear power plants related to explosives.