Sharif Digital Repository

The parameters within the reactor core can be categorized into two distinct groups of measurable parameters and unmeasurable parameters. The determination of unmeasurable parameters, such as void fraction and critical heat flux, plays a pivotal and fundamental role in predicting the occurrence of accidents and emergency situations within the reactor. The utilization of deep neural networks represents one of the methods for accurately and reliably estimating these parameters within future temporal intervals. Such estimations facilitate the implementation of necessary measures to prevent accidents or mitigate their consequences. In this study, we employ three deep neural network models namely... 

In this research, the thermohydraulic parameters of the reactor of Bushehr power plant have been compared between the activation or not of the emergency gas extraction (YR) system by the operator during the LB-LOCA accident, without access to the active part of the ECCS. Bushehr nuclear power plant reactor is of VVER-1000 type and has a primary and secondary circuit, which is completely modeled in this research. After the complete review and understanding of the primary circuit and its systems, the information required for modeling has been collected from the existing documents of the power plant, and after that, the modeling and sizing of the heart components and the four main rings and the... 

Evaluating the optimal performance of any dynamic system necessitates estimating its efficiency using simulation tools. MATLAB/Simulink is one of the most widely used and suitable simulation environments, enabling users to implement time-dependent differential equations governing the system, create corresponding models, and design appropriate controllers. This research aims to extract differential equations describing the dynamics of the main systems of the Bushehr nuclear power plant. Subsequently, using this simulation environment, the systems in question are implemented individually, and for each, an appropriate control system is designed based on its specific function. Ultimately, all... 

The widespread use of nuclear energy leads to obtain detailed information, such as neutron flux distribution (power) which is very effective in designing and evaluating the reactor safety. The neutron flux (power) reconstruction method uses the homogeneous flux distribution and the heterogeneous form function in a fuel assembly to calculate the heterogeneous power in the fuel rods. Therefore, this method has been widely developed in the last two decades. This study investigates to calculate two-dimensional and two-group neutron flux (power) in the fuel rod for both quadrilateral and hexagonal geometry related to core results by using nodal method. To achieve a more complete program and join... 

Fuel management in the core of nuclear power reactors is one of the most basic fields in nuclear engineering. Fuel management in the core is the problem of optimizing the design of the loading pattern because one of the ways to increase the economic performance and safety factor of nuclear power plants is to determine a suitable strategy for fueling in the core, in fact a reasonable loading pattern for competitive The development of nuclear power plants is very important. The optimal loading pattern can be defined as the configuration that has the maximum cycle length for a given fuel inventory or uses the minimum amount of fissile material for a given cycle length. From the past until now,... 

Sensors are one of the most important parts of safety and control systems in nuclear power plants. Failure to calibrate the sensors or their failure in a power plant and displaying incorrect values can lead to wrong and sometimes disastrous decisions. The first idea to check the sensors is to physically visit them. This method requires the reactor to be shut down and increase the radiation exposure of the operators and reduce the reliability and useful life of the equipment. Another approach is to use hardware redundancy. In this method, additional sensors are used to measure a variable, and the average value of the sensors is used as a reference for cross-checking. The limited available... 

Sensors are one of the most vital instruments in Nuclear Power Plants (NPP), and operators and safety systems monitor various parts of the NPP and control transients by analyzing the values reported by the sensors. Failure to detect malfunctions or anomalies in them would lead to catastrophic consequences. A new approach based on thermo-hydraulic simulation by RELAP5 code and Feed-Forward Neural Networks (FFNN) is given to detect faulty sensors and estimate their correct value which are two main objectives of the current study. This approach consists of two main parts; The first part, Fault Detection Hyper Block (FDHB), responsible for detecting faulty sensors, and the second part,... 

Data mining (DM) is one of the newest techniques which is used in decision making. DM helps the specialist to find the valuable knowledge which is hidden in data, with different techniques. DM has many research areas such as scientific research, medical fields, health care, fraud detection, marketing and customer relationship, sport, and games, and where ever there is data. Unfortunately, in our country, DM is not engaged seriously and there are fallacies of DM that weaken its efficiency. In this thesis, which is prepared in two sections, at the first section different techniques of DM are described and in the second section DM process is performed for a real world problem. For this purpose,... 

A major breakthorugh in all-optical wireless and wired communication networks is taking place in the last mile such as access networks. In this case، study-ing various multiple-access techniques in all-optical domain، especially optical code-division multiple-access (OCDMA) technique is of utmost importance. In this thesis we study several key signalings and modulation techniques in the con-text of their performance، energy and throughput efficiency for OCDMA systems. In particular we introduce novel multilevel signaling techniques for OOC-based fiber-optic CDMA systems and present their corresponding all-optical receiver structures using advanced optical devices such as optical-logic-gate... 

In this thesis a mutliScale model based on the Cauchy-Born hypothesis and via usage of XFEM is proposed for crack modeling. By solving an example, the important of surface effects in the surface stresses region is shown. Considering not being able to model the surface effects with the Cauchy-Born method, the boundary Cauchy-Born method for modeling crack effects is used. Moreover, three Molecular Dynamics method for modeling crack will be proposed. According to the obtained results from these methods, it was deduced that for calculating the correct surface stresses in Molecular Dynamics the mutual interaction of upper and lower atoms of crack should be omitted. Finally, the validation of... 

Modeling and Control of Ethylene Oxide Reactor In this thesis, steady and dynamic modeling of an ethylene oxide fixed bed reactor has been studied and one dimensional pseudo homogeneous model was used for simulating the reactor. Kinetic parameters were obtained by minimizing an object function and using the genetic algorithm. A good agreement is observed between simulation and experimental results. In steady state condition, the influence of some parameters such as shell temperature, feed rate were investigated on the performance of the reactor. The heat of reaction is used to produce steam. A dynamic model for steam drum was also considered and used for control purpose. A PI controller was... 

This thesis presents the development of a Finite Element Model (FEM) for a new type of Beam-Column Semi-Rigid steel connection. This connection consists of a steel semi cylinder connected to a plate and inserted on the top and bottom of the beam connecting it to the column by welding. It seems that changing the geometry of the semi cylinders and their weld lengths can have a great influence on the rigidity or flexibility of the connection. Therefore, meaningful categories of the connection with different semi cylinder geometries and weld lengths have been modeled and investigated by means of a Finite Element Modeling software ABAQUS, and their moment-rotation curves were driven. Also the...