Only 14 pages are availabe for public view
The thesis is composed of five chapters and presents the numer- ical results of the three dimensional full core modeling of the VVER-1200 reactor core in two phases of initial fuel loading under different modes of operation. The presented numerical results include the criticality and the neutronic safety parameters that characterized the VVER-1200 reactor core.
The first chapter exhibits an introduction about the impor- tance of nuclear power for electricity generation that lead to the development of nuclear reactors. Second, a detailed explanation for the reactor generation, followed by a historical review of the VVER evolution. Third, the importance of neutronic design of VVER reactor is briefly discussed. after that, a summary of the most intrinsic works that performed previously is introduced. At the end of this chapter, the objective and scope of the present work is presented.
The second chapter deals with the theoretical basis of neutron transport theory, followed by the methods of solution of transport equation. Also, an explanation of Monte Carlo methodology is introduced. The theoretical fundamentals of neutronic parame- ters including the effective multiplication factor, the reactivity coefficient, the effective delayed neutrons fraction and the power peaking factor are illustrated. The uncertainty evaluation of those parameters is also deduced. Further, the calculation of the coolant density under a certain operation criteria of pressure, temperature and boric acid concentration is explained, that is utilized in reactor
The third chapter presents a detailed description of VVER-1200 reactor core with the numerical methodology used which is Monte carlo method. A brief definition about MCNP5/MCNPX codes and the selected nuclear data library is introduced. Finally, the two models of VVER-1200 reactor core in two phases of partial and complete fuel loading are presented.
The fourth chapter exhibits the numerical results of criticality of VVER-1200 core in both first and second phases of initial fuel loading in cold and hot operational states, in addition to the crit- icality in normal operation state. The validation of two models of VVER-1200 reactor core with the available experimental and numerical resuls is investigated. The detailed analysis of neutronic safety parameters such as reactivity coefficients including tem- perature, void and boron coefficients, neutron spectrum in both the central and the reactor vessel regions, neutron flux in both radial and axial distributions, effective neutron delayed fraction, and power peaking factor is presented. At the end of this chap- ter, the variation of accumulated masses of both actinides and non-actinides with burn-up time of one year is deduced.
Ultimately, The fifth chapter includes the significant conclu- sions for each discussed parameter and the final conclusion of the study. Lastly, the chapter introduces the perspective suggestion and recommendations for the future work.