Papers by Keyword: Nuclear Power Plant

Abstract: Nuclear power plants (NPPs) result in accumulation of a significant amount of radioactive products during the process of their storage and the presence of a potential release of radioactive products, in the case of an accident that is a source of potential hazard and risk of radiation impact on the personnel, population and environment in general. The paper shows the microgalvanic corrosion element formed on the inner wall of fuel rods made of Zr + 1%Nb alloy and pellets made of uranium oxides, as well as the outer galvanic element of fuel rods and structural materials of the reactor made of steel of different grades. The hazards caused by corrosion damage and release of hazardous radioactive substances from the reactor based operating area are analyzed. The possibility of predicting the rate of corrosion damage using a mathematical model on the thermodynamic approach is determined and established.

Abstract: One of the factors limiting the operation time of nuclear reactor is corrosive wear of the reactor core structural materials and fuel element cladding due to continuous action of water coolant. Thus, for VVER (water-water energetic reactor) type reactors, local galvanic corrosion, which occurs between the surface of fuel element cladding made of zirconium alloy and various grade steel parts of other structural elements is peculiar. A short-circuited galvanic cell formed on the inner wall of Zr + 1% Nb alloy fuel elements is shown. Changes in oxide films thicknesses depending on the time at different water medium acidity are analyzed. A generalized model demonstrating that dissimilar metals in the reactor core (zirconium alloy and steel) form a short-circuited galvanic cell, resulting from which an increase in local corrosion of zirconium alloy occurs is presented.

Abstract: Population growth affects the increase in electrical energy demand in Indonesia. The energy is used to fulfill daily and industrial needs for improving welfare and sustainably advance society. Nuclear power plants (NPPs) are technologically advanced, reliable, and environmentally friendly electricity generators that can significantly reduce climate change. Current public policies related to the use of NPPs in Indonesia tend to bring the realization of nuclear power plants closer. This study aims to provide an overview of the development of public policies related to the use of NPPs in Indonesia. This study uses qualitative methods based on analysis of secondary data collected from various sources and literature. Data analysis is done by selecting, organizing, and presenting as a collection of information to be used for drawing conclusions. The results of the study indicate that the public policy perspectives have progressed towards supporting the use of NPP in supporting sustainable development. The increasing knowledge of public policy perspectives on the utilization of NPPs in Indonesia is important for educational and dissemination purposes as part of efforts to strengthen public acceptance.

Abstract: Extending the lifetime of energy facilities is extremely important today. This is especially true of nuclear power plants, the closure (or modernization) of which poses enormous financial and environmental problems. High-quality repair of reactors can significantly extend their service life. One of the critical parts is heat exchangers, the tubes of which quite often fail. Sealing, as a type of repair of heat exchanger tubes by the plugs, is promising provided that the joint quality is high. Practical experience in the use of welding to solve this problem has shown the need to search technological solutions associated with increasing the depth of penetration and reducing the area of thermal effect. The aim of the work was to develop a highly efficient technology for repair and extension of service life of heat exchangers of nuclear power plants based on the results of studying the technological features of laser welding of joints of dissimilar austenitic steels AISI 321 and AISI 316Ti in the vertical spatial position. Based on the results of the analysis of mechanical test data, visual and radiographic control, impermeability tests and metallographic studies of welded joints, the appropriate modes of laser welding of plugs have been determined. The principal causes of defects during laser welding of annular welded joints of dissimilar stainless steels are determined and techniques for their elimination and prevention of their formation are proposed. Based on the results of the research, technological recommendations for laser welding of plugs in the heat exchange tube of the collector are formulated, which significantly improves the technology of repair of steam generators of nuclear power plants and extends the service life of reactors.

Abstract: After the Fukushima Daichii accidents, Taiwan Power Company developed a strategy to cope with such extended SBO (Station Blackout) cases at nuclear power plants, which called URG. The MAAP and PCTRAN were used to perform the study for Kuosheng BWR/6 nuclear power plant (NPP) ultimate response guideline (URG). The main actions of URG are the depressurization and low pressure water injection of the reactor and the venting of the containment. This study focuses to confirm the URG efficiency. The analysis results depict that following the URG, the fuel can be covered by the coolant, no exposure. It can also prevent the radiation release and the large evacuation. It indicated that Kuosheng NPP was at the safe situation. It shows that the two-step depressurizations can extend the time of the preparation of alternate water source. The minimum injection rate to prevent the fuel to expose is 192 gpm in MAAP.

Abstract: During a long-term operation of nuclear power plants (NPP), the changes of structural material properties occur. To ensure the safe and reliable operation, it is necessary to monitor and evaluate these changes mainly on components from primary circuit of NPPs. One of the dominant ageing mechanisms of NPP components besides the radiation embrittlement and the fatigue loads is the thermal ageing. The thermal ageing is the temperature, material and time dependent degradation mechanisms due to long-term exposure at the operating temperature of 570 K.This paper describes the project for thermal ageing monitoring at primary piping in NPP Bohunice Unit 3. There are summarized the results obtained from evaluation of original primary piping material.

Abstract: We developed the equipment for splitting the long and small diameter tube, with using a splitting tool which was previously developed [1]. The splitting target is brass tube. Its length is about 500mm and the diameter is about 19mm. Because of the high aspect ratio, it is considered to cause a buckling easily. The developed equipment has a special gripping device for the long brass tube. Also the end of the long brass tube is gripped by the unique jig. As a result, it is shown that the brass tube (500mm length, 19mm of diameter and the thickness of the wall is 1.2mm) can be split in axial direction along its full length by using the developed tool and equipment.

Abstract: The energetic resources exploitation became a big issue in present days. Globally 30 countries in the world are also exploiting Nuclear Power Plants (NPPs) for the generation of energy. In this case energy production issue is correlated to the requirements for population safeguard against radiation leakage and to safe nuclear waste storing. However, many of these NPPs, which are still producing a large amount of energy, need or will need in short times a renewal process. Reinforced concrete members are of strong importance for the safety and for the proper operation of NPPs. One of the most important structural elements is then the reinforced concrete containment vessel, RCCV, of the reactor. The correct prediction of the RCCV behaviour under sever action is essential for the assessment of existing structure safety and for the design of new ones. In the paper it is described the modelling of a 1/13 scaled reinforce concrete containment vessel tested at the National Center for Research on Earthquake Engineering of Taipei, Taiwan, under cyclic loading. The RCCV was analyzed by means of non linear finite elements analysis using multi layered shell elements. A secant total strain fixed crack model called PARC_CL, implemented at the University of Parma in the user subroutine UMAT.for in ABAQUS code, has been used to evaluate the mechanical non-linearity of RC elements. The multi layered shell elements approach with PARC_CL crack model provided good results in terms of local and global EDPs and it was able to give a good estimation of the post cracking behaviour until failure. Simulations results are provided in terms of displacements, strains and crack patterns. Although analyses provided good results, some issues like the modelling of the structure to foundation interface are still open.

Abstract: The cracking susceptibility of a WSTE-51 steel for pressurized container of a nuclear power plant was evaluated. This evaluation was performed by means of the Controlled Thermal Severity Test and the Cold Cracking TEKKEN Test, as well as the VINCKIER Test for reheating cracking. Conventional mechanical tests and metallographic examinations were performed to characterize additional properties of the welding. The results indicated that the weldment has susceptibility to crack formation. Procedures to avoid this susceptibility were discussed.

Abstract: This paper describes the nonlinear probabilistic analysis of the failure pressure of the shielding plate of the reactor box of the nuclear power plant under a high internal overpressure and temperature. The scenario of the hard accident in Nuclear power plant (NPP) and the methodology of the calculation of the fragility curve of the failure overpressure using the probabilistic safety assessment PSA 2 level is presented. The fragility curve of the failure pressure was determined using 45 probabilistic simulations using the response surface method (RSM) with the Central Composite Design (CCD) for 10⁶ Monte Carlo simulations for each model and 5 level of the overpressure.