International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

There are numerous methodological approaches for modelling, numerical analysis and/or simulation of the behaviour of individual systems. However, modelling the interdependencies between task-oriented or dedicated systems (the so-called system of systems) and describing their complex behaviour, necessarily through simulation, is still an unsolved issue.

According to Art. 3 of the Bulgarian Safe Use of Nuclear Energy Act, nuclear energy and ionizing radiation are used in accordance with the requirements and principles of nuclear safety and radiation protection in order to ensure the protection of human life, health and living conditions of current and future generations, the environment and material values from the harmful impact of ionizing radiation. Persons responsible for facilities and activities under this Act shall establish and maintain an effective safety management system.

The role of management at a nuclear facility is to perform functions such as planning, organizing, staffing, leading and directing work, controlling, monitoring and assessing work and evaluating results. Management systems are methods, processes and tools used by the managers of a nuclear facility to create a framework to carry out work in a safe and secure manner while ensuring that the objectives of the facility operator are achieved within the legal and regulatory framework of the country.

The development of a combustion concept for hydrogen-fuelled high-speed large engines requires a suitable development methodology, including the interaction between 1D and 3D simulation as well as experimental investigations on research engines. The main subject of this paper is the development of one-dimensional single cylinder and multi cylinder engine models used for turbo matching and to gain a better understanding of combustion anomalies. The latter are especially affected by the mixture formation process which is investigated by means of 3D CFD simulations for port fuel injection and direct injection engine operation. Boundary conditions are generated based on experimental investigations on a single cylinder research engine with displacement of about 6 liters. The paper concludes with an assessment of the benefits and limitations of different engine configurations.

This report identifies the main objectives and responsibilities of the operating organization for the selection, qualification and training of personnel for new and existing nuclear power plants to establish and maintain a high level of competence of personnel and to ensure safe operation of the nuclear power plant. The publication can also be used as a recommendation for the recruitment, training and qualification of personnel for nuclear installations other than nuclear power plants.

The main subject of this paper is the development of a multicylinder engine model for the prediction of knocking combustion and emissions such as nitrogen oxide and unburned hydrocarbons based on one-dimensional simulation. The one-dimensional simulation is widely used for combustion system layout and determination of operating parameters to achieve performance targets and comply with emission limits. The paper focuses especially on the prediction of the unburned fuel mass from the combustion process and from the scavenging during the valve overlap. The calibration of the sub-models is based on measurements on a single cylinder research engine with a displacement of approximately 6 litres. The simulation results are validated with experimental measurement results on the same research engine. The paper concludes with statements about the predictive capability of the model.

Sensitive information is information, in whatever form, including software, the unauthorized disclosure, modification, alteration, destruction, or denial of use of which could compromise nuclear security. Confidentiality is the property that information is not made available or disclosed to unauthorized individuals, entities or processes. Information security not only includes ensuring the confidentiality of information, but also includes ensuring the accuracy and completeness of the information (its integrity) and the accessibility or usability of the information on demand (its availability).

The main subject of this paper is the development of a multicylinder engine model for the prediction and optimization of engine performance based on one-dimensional (1D) simulation. 1D simulation is widely used to preoptimize engine geometry and operating parameters to achieve performance targets and comply with operational and emission constraints. Due to the short calculation times, 1D simulation allows the evaluation of a larger number of variants. As new engine concepts are developed, many operating parameters are first defined and optimized with a 1D multicylinder engine model. This model illustrates the full complexity of the engine with its geometry, turbocharging and combustion parameters. In this paper the design of experiments (DoE) method is used in connection with 1D simulation to determine the optimal engine configuration as well as parameters related to the combustion process, i.e., valve timing, compression ratio, ignition timing, excess air ratio. This approach enables the determination of the maximum engine efficiency while taking the boundary conditions and the constraints of nitrogen oxide emissions (NOx) and knock into account. The method also enables the reduction of the cylinder-to-cylinder deviations by improving the gas dynamics and the fuel metering in the main combustion chamber and in the prechamber, which is especially important for the multicylinder engine. The simulation results are validated with experimental investigations on a single cylinder research engine.

The protection of nuclear installations against malicious acts can take a number of different forms. This report addresses only issues related to the sabotage of nuclear facilities – prevention or mitigation of sequences initiated by malicious acts that may have potential radiological consequences. Nuclear power plants have good physical protection systems (PPSs) and procedures, and they are designed to minimize the likelihood of an accident and in the event of an accident, not to release radioactive material in an uncontrolled manner. The objective of this report is to provide methods for evaluating and for proposing corrective actions aimed at reducing the risk related to any malicious act that, directed against a nuclear power plant, could endanger the health and safety of plant personnel, the public and the environment.

One of the main threats to nuclear facilities can involve external or insider adversaries or both together in collusion (coop eration for an illegal or malicious purpose with another insider adversary or with an external adversary). In these case, the main effort is to prevent and protect against unauthorized removal of nuclear material and sabotage of nuclear material and facilities by insiders. This report applies to any type of nuclear facility – notably nuclear power plants, research reactors and other nuclear fuel cycle facilities – whether in design, construction, commissioning, operation, shutdown or decommissioning

The lifetime of a nuclear facility extends from the earliest planning stages through to its decommissioning. It is important to consider nuclear security early in the design of new facilities and during partial redesigns or modifications, as it can result in nuclear security for these facilities that is more efficient, more effective and better integrated with other safety, safeguards, operational and other measures. Nuclear security measures are also important during commissioning and operation, they should not cease at decommissioning, as they are important in addressing the protection of the remaining quantities of nuclear material or other radioactive ma terial, which has accumulated during the operations stage.

The potential for criminal or intentional unauthorized acts involving or directed at nuclear or other radioactive material or their associated facilities and associated activities is an ongoing global concern. Because of their widespread use, nuclear and other radioactive materials are vulnerable to sabotage, or to being stolen, lost or acquired illegally by individuals or groups that may use th em for malicious purposes. The objective of a nuclear security regime is to prevent, detect and respond to nuclear security events, and to protect persons, property, society and the environment from harmful consequences associated with nuclear and other radioactive materials.