Nuclear Power Plant Protection Research Articles

Правовые вопросы безопасности АЭС в зоне военных действий

The article discusses the legal aspects of physical protection and nuclear safety of nuclear power plants located in a combat zone. The existing multilateral international treaties in this area, namely, the 1979 Convention on the Physical Protection of Nuclear Material (CPPNM) and the 2005 Amendment to the 2005 Convention on the Physical Protection of Nuclear Material, do not regulate the physical protection of nuclear facilities located in areas of active combat using conventional weapons. Moreover, the IAEA soft law provisions do not regulate the issues of physical protection of nuclear power plants located in areas of full-scale combat operations. The situation with the Zaporizhzhia Nuclear Power Plant has made the international community and the IAEA face the issue of legal regulation and development of recommendations for the physical protection of nuclear facilities in a war zone. Currently, a new concept for the physical protection of the Zaporizhzhia Nuclear Power Plant is being discussed under the auspices of the IAEA and efforts to prepare a new international treaty on the physical security of nuclear facilities in a war zone are underway.

ОБҐРУНТУВАННЯ НЕОБХІДНОСТІ ОЦІНЮВАННЯ МОЖЛИВОСТЕЙ ВІЙСЬКОВИХ ЧАСТИН НАЦІОНАЛЬНОЇ ГВАРДІЇ УКРАЇНИ ЩОДО ОБОРОНИ ОБ’ЄКТІВ КРИТИЧНОЇ ІНФРАСТРУКТУРИ

At the beginning of the full-scale invasion of the Russian Federation into the territory of Ukraine, the aggressor seized critical infrastructure facilities that were located in the occupied territories. Among especially dangerous objects of critical infrastructure there are two nuclear power plants: Chernobyl and Zaporozhye. So, the Chernobyl nuclear power plant was captured by Russian troops on February 24, 2022 and controlled by them until March 31, 2022. And the Zaporozhye NPP was captured by the invaders on March 4, 2022 and is under their control. Based on the analysis of certain events, it can be concluded that the units of the National Guard of Ukraine were unable to ensure the defense of the stations, which, in accordance with the current legislation, is their direct function. The reason for this was the mistakes made by the military authorities in assessing the capabilities of the military units of the National Guard of Ukraine for the protection of nuclear power plants for the defense of the facilities entrusted to them. The solution to this problem in the future may be to improve the theory of assessing the capabilities of the military units of the National Guard of Ukraine regarding the protection and defense of critical infrastructure. For this purpose, the article analyzes the existing scientific and methodological apparatus and policy documents on the organization and implementation of the protection and defense of critical infrastructure facilities under martial law by the military units of the National Guard of Ukraine. As a result of the analysis, some problems were identified in the defense of nuclear power plants, as well as in the organization of management at the tactical level during the organization of the defense of critical infrastructure facilities, including nuclear power plants. Also, directions for further research were identified, namely: the settlement of the issue of subordination in the performance of combat missions for the protection and defense of critical infrastructure facilities at the tactical level, as well as the improvement of the theory of assessing the capabilities of the military units of the National Guard of Ukraine for the protection and defense of nuclear power plants, taking into account modern threats.

Международно-правовая защита АЭС в условиях вооруженного конфликта

The article considers the international legal framework for the protection of nuclear power plants (NPP) from the threats of attack and destruction in the conditions of two types of armed conflicts from the standpoint of a conceptual and practice-oriented approach. The scientific materials define the criteria for general and special protection of such nuclear facilities, as well as the conditions for the termination of legal protection as a last resort. As a result of the study, conclusions were formulated that determine the rules of conduct for the parties to the conflict in protecting nuclear power plants in the conditions of warfare. The presented material is updated with a brief analysis of the events taking place around the Zaporozhye NPP as part of its systematic shelling by the Ukrainian armed forces.

УДОСКОНАЛЕННЯ ЗАКОНОДАВСТВА УКРАЇНИ ЩОДО ЗАХИСТУ АЕС ЯК ОБ'ЄКТІВ КРИТИЧНОЇ ІНФРАСТРУКТУРИ У ВІЙСЬКОВИЙ ЧАС

Peculiarities of the legal regime of protection of nuclear power plants as objects of critical infrastructure in emergency situations, state of emergency and while martial law are studied. The actual transformation of nuclear power plants captured by the Russian Federation into a military base contradicts the ideological issue and worldview of security and thus can be defined as nuclear terrorism. Any nuclear installations are not designed for operation in combat conditions, and their damage can lead to serious consequences connected with radiation contamination of the surrounding territories not only at the level of countries, but also at the level of continents. It is stipulated that until now the concept of nuclear terrorism was defined as the illegal handling, manufacture, acquisition, storage and use of nuclear or other radioactive materials by persons who do not have legal rights to the specified actions, with the intention of causing harm to human life and health, property or environment. However, for the first time in world practice, the subject of the crime of seizing, disabling and destroying nuclear facilities is the state. And as it turns out, the international community still lacks effective mechanisms to prevent such actions and punish such entities. Until recently, the IAEA and other international organizations were actually limited to "deep concern" and only the real threat of a nuclear disaster at the Zaporizhzhia NPP forced them to become somewhat more active, but drastic changes in their activities regarding the safety of the use of peaceful atoms are needed to protect the world from the global nuclear threat. This provoked incredible challenges and led to the need, in addition to the political solution of the mentioned issue, to review the existing Ukrainian and international legislation on ensuring nuclear and radiation safety. Based on the results of the research, the author's specification of the legislative definition of the concepts: "nuclear terrorism," "threat of nuclear terrorism," and "prevention of nuclear terrorism" were formulated. The necessity of introducing demilitarized zones around nuclear-dangerous objects and the development (on Ukraine's initiative) of the international Convention on ensuring the safety of their functioning in conditions of armed conflicts is substantiated in the paper. The research used the following methods: the general dialectical method, the method of scientific knowledge, the method of interpreting legal norms, the formal legal method, the comparative legal method, and the method of systemic analysis.

Review of studies on effect of gadolinium alloying on properties of corrosion-resistant steels. Part 1. Effect of gadolinium on properties of micromelts made of corrosion-resistant steel

The effect of gadolinium on the properties of corrosion-resistant steels used to ensure nuclear safety during the temporary storage, transportation and final disposal of spent nuclear fuel is studied. It is revealed that at present there is great interest in replacing boron with gadolinium for the absorption of thermal neutrons in alloys, which is a global trend. It is established that gadolinium, being a lanthanide, has the largest thermal neutron capture cross section and, despite its high atomic mass, remains the most effective neutron absorber that can potentially ensure the nuclear safety required for temporary storage, transportation and final disposal of spent nuclear fuel. The results of analytical studies can be used as a methodological material for laying of the foundations for the widespread use of gadolinium-containing materials in advanced designs of neutron absorbers, temporary and centralized storage facilities and containers for transporting spent nuclear fuel, as well as in the construction of shields for the protection of nuclear power plants.

Considerations for modeling of base isolated nuclear power plants subjected to beyond design basis shaking

Modeling of the seismic isolation system plays a key role in simulating the seismic response of base isolated nuclear power plants (NPP), including estimation of peak isolator displacement and potential to exceed the clearance to stop. Under beyond design basis shaking, seismic isolators such as lead rubber bearings (LRB) may undergo large displacements and exhibit complex behavior including cyclic heating causing strength degradation of the lead and strain hardening in the rubber at large strains. Displacement demands on the isolation system can be limited by a stop such as a moat wall to prevent bearing failure, with the impact to the moat having potential to increase the transfer of forces to the superstructure. Towards a more accurate seismic assessment of NPP subjected to beyond design basis shaking, a model of a seismically isolated NPP is developed with advanced modeling capabilities for LRB isolators and simulation of moat wall impact. The bearing models capture the cyclic behavior of LRB as observed in measured experimental data from full-scale bearings designed for NPP applications. The moat wall model considers a concrete retaining wall with backfill soil and contact elements developed based on experimental data and high-fidelity Finite Element Method (FEM) simulations. The simulation tools are used to evaluate the consequences of bearing modelling and impact to moat walls on the seismic performance of NPP and further develop effective mitigation measures for the seismic protection of NPP. As a result of the studies presented here, a simplified design methodology to estimate impact response parameters including moat wall deformation due to impact, impact velocities, and forces is proposed.

Vital area identification for the physical protection of NPPs in low-power and shutdown operations

Vital area identification (VAI) is an essential procedure for the design of physical protection systems (PPSs) for nuclear power plants (NPPs). The purpose of PPS design is to protect vital areas. VAI has been improved continuously to overcome the shortcomings of previous VAI generations. In first-generation VAI, a sabotage fault tree was developed directly without reusing probabilistic safety assessment (PSA) results or information. In second-generation VAI, VAI model was constructed from all PSA event trees and fault trees. While in third-generation VAI, it was developed from the simplified PSA event trees and fault trees.While VAIs have been performed for NPPs in full-power operations, VAI for NPPs in low-power and shutdown (LPSD) operations has not been studied and performed, even though NPPs in LPSD operations are very vulnerable to sabotage due to the very crowded nature of NPP maintenance. This study is the first to research and apply VAI to LPSD operation of NPP. Here, the third-generation VAI method for full-power operation of NPP was adapted to the VAI of LPSD operation.In this study, LPSD VAI for a few plant operational states (POSs) was performed. Furthermore, the operation strategy of vital areas for both full-power and LPSD operations was discussed. The LPSD VAI method discussed in this paper can be easily applied to all POSs. The method and insights in this study can be important for future LPSD VAI that reflects various LPSD operational states. Regulatory bodies and electric utilities can take advantage of this LPSD VAI method.

Assessment of atmospheric dispersion stability based on the atmospheric boundary layer monitoring at the Belorussian nuclear power plant site

Due to the fact that the potential threat to the health to the public living near nuclear power plants is largely determined by the level of air pollution by radionuclides, identification of the dispersion conditions of pollutants in the atmospheric boundary layer is of great importance in the development of engineering protection means for nuclear facilities. In turn, the engineering protection of nuclear power plants provides for the development of automated radiation monitoring systems and their main components, i. e. atmospheric boundary layer status monitoring systems. When analyzing and predicting the radiation situation in the vicinity of nuclear power plants, the determination of atmospheric dispersion variability parameters over time is essential. This research is aimed at assessing interannual and intra-annual variability of atmospheric dispersion parameters in the Belorussian nuclear power plant siting region based on the atmospheric boundary layer monitoring data. This study has revealed the relative interannual stability of the main average annual atmospheric dispersion characteristics throughout the observation period in 2015-2019. At the same time, the average seasonal values of the atmospheric boundary layer dispersion parameters are characterized by significant fluctuations thereof over the annual course. The feasibility of such monitoring for other potentially hazardous industrial facilities, such as thermal power plants and chemical plants, is also noted.

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Recently, the number of incidents of damage of important state or military facilities by criminals using unmanned aerial vehicles has increased. The task of covering nuclear power plants in the airspace is entrusted to the forces and means of anti-aircraft missile forces of the Armed Forces of Ukraine. They are mainly designed for the destruction of large-sized unmanned aerial vehicles and at long distances. However, when criminals use small-sized unmanned aerial vehicles at short distances from a nuclear power station in order to reconnoiter the territory of nuclear power stations or damage vital centers of the station with attack unmanned aerial vehicles, anti-aircraft missile forces of the Armed Forces of Ukraine may not be effective. Therefore, military units for the protection of nuclear power plants, which are allocated from the National Guard of Ukraine, must have their own system to counter unmanned aerial vehicles.When building such a system, before putting it into operation, it is necessary to assess the ability of the system to perform tasks to counter unmanned aerial vehicles, taking into account many factors and parameters, which raises the problem of such an assessment. Therefore, in order to solve a specific problem, the article developed a model for countering unmanned aerial vehicles by the forces and means of military units to protect nuclear power plants. The developed model estimates the probability of detection and, with the help of a queuing system, the probability of destroying unmanned aerial vehicles, which can help the command of military units to protect nuclear power plants to make informed decisions on building a system to counter unmanned aerial vehicles. In the article, in order to verify the suitability of the developed model for its intended use, calculations have been performed for conditions close to the real ones.

Model-Checking Detailed Fault-Tolerant Nuclear Power Plant Safety Functions

Model checking has been successfully used for detailed formal verification of instrumentation and control (I&C) systems, as long as the focus has been on the application logic alone. In safety-critical applications, fault tolerance is also an important aspect, but introducing I&C hardware failure modes to the formal models comes at a significant computational cost. Previous attempts have led to state space explosion and prohibitively long processing times. In this paper, we present an approach to model and formally verify protection functions allocated to one or several I&C systems, accounting for hardware component failures and delays in communication within and between the systems. Formal verification is done with model checking, whose feasibility on such complex systems is achieved by utilizing the symmetry of I&C systems: the components of the overall model that do not influence the checked requirements are eliminated, and the failing components are fixed. Generation of such abstracted models, as well as subsequent verification of their requirements and symmetry with the NuSMV symbolic model checker, is handled by a software tool. In addition, we explore how to specify formal requirements for systems of the considered class. Based on a case study built around a semi-fictitious nuclear power plant protection system that achieves reliability by means of redundancy, we demonstrate how failure tolerance of even detailed system designs can be formally verified.

Seismic isolation of small modular reactors using metamaterials

Adaptation of metamaterials at micro- to nanometer scales to metastructures at much larger scales offers a new alternative for seismic isolation systems. These new isolation systems, known as periodic foundations, function both as a structural foundation to support gravitational weight of the superstructure and also as a seismic isolator to isolate the superstructure from incoming seismic waves. Here we describe the application of periodic foundations for the seismic protection of nuclear power plants, in particular small modular reactors (SMR). For this purpose, a large-scale shake table test on a one-dimensional (1D) periodic foundation supporting an SMR building model was conducted. The 1D periodic foundation was designed and fabricated using reinforced concrete and synthetic rubber (polyurethane) materials. The 1D periodic foundation structural system was tested under various input waves, which include white noise, stepped sine and seismic waves in the horizontal and vertical directions as well as in the torsional mode. The shake table test results show that the 1D periodic foundation can reduce the acceleration response (transmissibility) of the SMR building up to 90%. In addition, the periodic foundation-isolated structure also exhibited smaller displacement than the non-isolated SMR building. This study indicates that the challenge faced in developing metastructures can be overcome and the periodic foundations can be applied to isolating vibration response of engineering structures.

APPLIED INFORMATICS MODEL ОF KINETICS ACCOUNTING OF CYBERNETIC THREATS IN NPP PHYSICAL PROTECTION SYSTEM

Context. The topical approaches to preventive estimations and mathematical modeling of cyber attacks processes and supply of external technological informational threats were considered, which may be directed on the physical security system of modern nuclear power plant units. Objective – is an adaptation of known mathematical models of cyber attacks kinetics for use in the system of information security and physical protection of nuclear power plants to modern and foreseeable conditions. Method. The method of model dependencies adaptation was proposed, which reflects the kinetics of cyberattacks to the modern operating conditions of protected nuclear facilities was proposed. To improve the model dependencies it was proposed to modify the classic Ferhulst function and, in mathematical modeling of cyber attacks on nuclear power facilities, to use the appropriate transformation of the logistic curve, which has distinctive feature of a well-defined maximum. Results. It was predicted that the model dependence of flow external to NPP cyber threats can be characterized by the alternation of maxima and minima, which indicates the possibility of an oscillatory character of the developing process. Also was put forward and substantiated the hypothesis that the system of physical and, in particular, cybernetic, NPP protection can be characterized by a time lag that in view of possible oscillatory character of information threats admissions process creates the preconditions for the development of oscillatory instability. The results obtained in the research are of applied nature, they can be used to carry out large-scale experiments and forecasting parameters of possible cyber threats aimed at the NPP for the purpose of pre-emption and preventive maintenance of information safety of modern nuclear energy technologies. Conclusions. Recommended for use model dependences were first adapted to the conditions of operating conditions of nuclear powerfacilities, take into account the factors to counter threats and circumstances associated with a specific time delay. It was shown for the first time that there is an opportunity both extreme and oscillatory dependence nature of the cyber attacks intensity, which are focused on software and hardware system of NPP information safety. The new approach allows to assume the reality of the unstable oscillation process in the “attack – defense” system and provides an opportunity of preventive assessment of the stability stocks. The practical significance lies in the fact that the results allow to realistically assess the time of onset of expected cyber attacks current dependence changes and to use this knowledge for organizational and technical preparation of remedies and early anticipation of IT-threats.

Временной механизм воздействия опасных факторов пожара на персонал АЭС и комплексная защита от них

Проведен анализ пожаров на объектах атомной энергетики. С помощью расчетно-аналитических исследований динамики пожаров для типовых помещений АЭС определены критические времена достижения опасными факторами пожара критических значений для людей на уровне рабочей зоны. Дан анализ прибытия пожарных подразделений по охране АЭС на территорию станций при пожарах. Рассмотрен перечень средств защиты и технического оснащения оперативного персонала щитов управления АЭС. Разработаны мероприятия по комплексной защите оперативного персонала АЭС, проводящего специальные работы по выработке электрической энергии при пожарах в условиях воздействия опасных факторов. Проведены комплексные испытания технических средств для обеспечения действий оперативного персонала при пожаре с использованием учебно-тренировочных комплексов.

Improvement of impact-resistance of a nuclear containment building using fiber reinforced concrete

Since the act of terrorism that occurred in the USA on September 11, 2001, the protection of nuclear power plants against large commercial aircraft crashes has been an emerging issue. Besides the verification of the safety of nuclear power plants in operation or in design, efficient methods for improving the impact-resistance of these structures have been investigated. Fiber reinforced concrete (FRC) has been generally accepted as an effective material for this purpose. In particular, FRC has been developed to improve the tensile behavior of concrete such as tensile strength, ductility and toughness. One of the main fields of application of FRC can be found in blast-protective or blast-resistant concrete structures. It is expected, therefore, that safety-related structures in a nuclear power plant can also be effectively protected from external blast, aircraft crash, etc. by applying FRC. In order to analytically verify the effect on structural behavior of applying FRC, the particular material properties of FRC should be incorporated into the material modeling of a structural analysis program. This study investigates the mathematical modeling of FRC, which represents various aspects of material behavior. Two numerical examples are provided to show the improved impact-resistance of a nuclear containment building that is expected when applying FRC in comparison with ordinary concrete. The analysis results show that the displacement decreases by 43–67% while the impact-resistance increases by 40–82%, depending on a fiber type.

Interaction and Coordination among Nuclear Power Plants, Power Grids and Their Protection Systems

Nuclear power plants (NPPs) have recently undergone rapid development in China. To improve the performance of both NPPs and grids during adverse conditions, a precise understanding of the coordination between NPPs and grids is required. Therefore, a new mathematical model with reasonable accuracy and reduced computational complexity is developed. This model is applicable to the short, mid, and long-term dynamic simulation of large-scale power systems. The effectiveness of the model is verified by using an actual NPP full-scope simulator as a reference. Based on this model, the interaction and coordination between NPPs and grids under the conditions of over-frequency, under-frequency and under-voltage are analyzed, with special stress applied to the effect of protection systems on the safe operation of both NPPs and power grids. Finally, the coordinated control principles and schemes, together with the recommended protection system values, are proposed for both NPPs and grids. These results show that coordination between the protection systems of NPPs and power networks is a crucial factor in ensuring the safe and stable operation of both NPPs and grids. The results can be used as a reference for coordination between NPPs and grids, as well as for parameter optimization of grid-related generator protection of NPPs.

Calculations for AP1000 nuclear power plant SGTR accident based on RELAP5/mod 3.3 program

AP1000 nuclear power plant model is founded via RELAP5/mod 3.3 program in detail. Refer to SGTR accident basic assumptions in the safety analysis report, calculations for AP1000 nuclear power plant SGTR accident are carried out. And through comparison between the result got and the result from safety analysis report calculated by LOFTTR2 program, the two results are very consistent. It's found that even if the operators do not interfere, AP1000 nuclear power plant protection systems and passive design measures will trigger an automatic response measures, it can terminate the SG heat transfer tube leaking and make RCS be stable in a safe condition and to prevent SG overflowing and ADS actions occurring.

Wartime Nuclear Power Plant Security Protection Research

Nuclear power as an important energy which benefits human being,is being more and more widely used in many countries all over the world. Under the condition of information war, threat to nuclear power plant security from precision weapon and terrorist attack is serious. This paper analyzes major threats nuclear power plant be facing to in wartime such as obvious exposure symptoms, limited own protections and large impact on the war potential. Then several main methods are discussed to strengthen safety protection of nuclear power plant. Firstly, strive to improve the early warning ability of nuclear power plant. By this means, more time can be obtained to make nuclear power plant protection to prepare. Secondly, counterattacks, interference and disguise simultaneously should build another effective barrier. In the last, it is considered that research on protection and rescue of nuclear power station should be strengthened also.

ICONE15-10201 PRESENT STATUS OF NUCLEAR CONTAINMENTS IN KOREA

Since the first nuclear power plant in Korea, Kori unit #1, was started in commercial service in 1978, 20 units including Kori unit #1 have been operated and maintained until now in Korea. Recently several units were started to be constructed and also, additionally more than 4 units were planned to be constructed in the near future. The importance of nuclear containments has been always one of the hottest issues for the safety and protection of nuclear power plants until now. At the beginning of nuclear power plants construction in Korea, several typed nuclear containment systems were adopted. For those reasons, various codes, standards, and inspection technologies are applied to nuclear containment systems differently. In this study, the status of inservice inspection performed for the safety and maintenance of nuclear containments in Korea was researched. Overall nuclear containment systems and inspections performed up to recently in Korea including trends, inspection items, periods, and regulations were described briefly.

스윙형 역지밸브의 고장 원인 분석과 열림 특성에 관한 실험적 연구

Check valves play a vital role in the operation and protection of nuclear power plants. Check valves failure in nuclear power plants often lead to a plant transient or trip. The analysis of historical failure data gives information on the populations of various types of check valves, the systems they are installed in, failure modes, effects, methods of detection, and the mechanisms of the failures. A majority of check valve failures are caused by improper application. The experimental apparatus is designed and installed to measure the disc positions with flow velocity, Vopen and Vmin for 3 inch and 6 inch swing check valves. The minimum flow velocity necessary to just open the disc at a full open position is referred to as Vopen, and Vmin is defined as the minimum velocity to fully open the disc and hold it without motion. In the experiments, Vmin is determined as the minimum flow velocity at which the back stop load begins to increase after the disc is fully opened or the oscillation level of disc is reduced below 1°. The results show that the Vmin velocities for 3 inch and 6 inch swing check valves are about 27.3% and 17.5% higher than the Vopen velocities, respectively.

Comment on: development of a safety critical software requirements verification method with combined CPN and PVS: a nuclear power plant protection system application

Comment on: development of a safety critical software requirements verification method with combined CPN and PVS: a nuclear power plant protection system application