This master's thesis deals with the sequence of events that led to the nuclear accident at the Three Mile Island nuclear power plant. We plan to illustrate the events with the help of a nuclear power plant simulator that is designed to model a two-loop power plant. The nuclear power plant in the PCTran PWR simulator and the Three Mile Island nuclear power plant are distinguished from each other by the design of the reactor coolant system. The former features a classic two-loop design, where each of those loops has its own reactor coolant pump and a cold leg which runs the cooling water from the steam generator into the reactor. The latter has two additional cold legs, resulting in two supplementary reactor coolant pumps, all together four reactor coolant pumps (two for each loop).
The first part presents the development and analysis of the events with all necessary information because it is crucial for a better understanding of the simulation’s procedure. The second part includes the presentation of the PCTran PWR version 6.0.1 simulator which was used to approximate the exact course of events. The third or the main part of the master’s thesis is based on the simulation of the accident’s course of events under the given scenario; therefore, the scenario is introduced before presenting the obtained results. The attempt was to use the simulation in order to approximate the exact chronology of the nuclear accident since the intention was to present the scenario of the course of events in a similar power plant that is not absolutely identical to the Three Mile Island power plant in its design. In both cases, we have power plants with a pressurized water reactor.
Selected parameters were included for their comparison: the mass flowrate of water in the hot and cold leg of the reactor coolant system, reactor coolant system pressure, steam generator pressure together with the hot and cold leg temperature. Bearing in mind that the simulation and the adjusted scenario were used to approximate the exact chronology of the events and that only certain initial conditions from the moment of the accident were available, the following conclusion was reached: the simulation graphically illustrates and presents the course of events, which helps to gain a deeper understanding of the events as well as understanding the functioning of the nuclear power plant systems. From the obtained results we can read the flow chart of the nuclear power plant’s parameter values and their timeline, thus discovering more in detail how a nuclear power plant operates and how its parameters correlate. It can be seen that the nuclear power plants with pressurized water reactors are safe since even the reactor’s core meltdown, which occurred at Three Mile Island nuclear power plant, did not cause any severe radiological environmental pollution or threaten the health and lives of the employees and did not endanger the public.
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