Simulacija scenarija jedrske elektrarne Otoka treh milj za primer dvozančne elektrarne

GREGL, SARA (avtor), Čepin, Marko (mentor)

Magistrsko delo obravnava zaporedje dogodkov, ki je pripeljalo do jedrske nesreče v jedrski elektrarni na Otoku treh milj, ki jih želimo prikazati s pomočjo simulatorja jedrske elektrarne, ki je namenjen modeliranju dvozančne elektrarne. Jedrska elektrarna v simulatorju PCTRAN PWR se od elektrarne na Otoku treh milj razlikuje po izvedbi sistema reaktorskega hladila. Prva ima klasično izvedbo z dvema zankama, pri kateri ima vsaka svojo reaktorsko črpalko in hladno vejo, ki vodi hladilno vodo iz uparjalnika v reaktor, medtem ko ima slednja dodani še dve dodatni hladni veji ter posledično tudi dve dodatni črpalki reaktorskega hladila več, skupaj torej štiri črpalke reaktorskega hladila (dve na eno zanko). V prvem delu sta predstavljena potek in analiza dogodkov z vsemi potrebnimi podrobnostmi, saj je to ključno za lažje razumevanje poteka simulacije. V drugem delu sledi predstavitev simulatorja PCTRAN PWR verzije 6.0.1., s katerim sem se poskušala približati dejanskemu poteku dogodkov. Tretji oziroma glavni del magistrskega dela pa temelji na simulaciji poteka dogodkov po zastavljenem scenariju, zato je pred predstavitvijo dobljenih rezultatov tudi najprej predstavljen scenarij. S simulacijo sem se poskušala približati dejanskemu časovnemu poteku dogodkov, saj je bil namen, da bi s pomočjo simulacije prikazala scenarij poteka dogodkov v podobni elektrarni, ki po izvedbi ni popolnoma identična jedrski elektrarni na Otoku treh milj. V obeh primerih pa gre za elektrarni s tlačnovodnim reaktorjem. Med pomembnejše primerjane parametre so sodili masni pretok vode v vroči in hladni veji sistema reaktorskega hladila, tlak sistema reaktorskega hladila, tlak v uparjalnikih ter temperaturi vroče in hladne veje. Poleg tega smo prikazali še nekaj drugih parametrov elektrarne. Ob zavedanju, da smo se s simulacijo in prilagojenim scenarijem poskušali približati dejanskemu poteku dogodkov, ter da sem imela na voljo le določene začetne pogoje iz trenutka nesreče, je bil ugotovljen naslednji zaključek. Simulacija nazorno uprizori in predstavi zaporedje dogodkov, kar je v pomoč pri njihovem razumevanju in pri razumevanju delovanja sistemov jedrske elektrarne. Iz dobljenih rezultatov lahko odčitamo potek vrednosti parametrov elektrarne in njihov časovni potek in tako še podrobneje spoznamo delovanje jedrske elektrarne, in medsebojne odvisnosti njenih parametrov. Ugotovimo lahko, da so tlačnovodne jedrske elektrarne varne, saj tudi taljenje sredice reaktorja, ki se je zgodilo v elektrarni na Otoku treh milj, ni povzročilo kakšnega pomembnega radiološkega onesnaženja okolice in tudi ni ogrozilo zdravja in življenj zaposlenih in ni ogrozilo prebivalstva.

• Jezik: Slovenski jezik
• Ključne besede: tlačnovodni jedrski reaktor, simulator jedrske elektrarne, elektrarna na Otoku treh milj, varnost
• Vrsta gradiva: Magistrsko delo/naloga
• Organizacija: FE - Fakulteta za elektrotehniko
• Leto izida: 2017
• PID: 20.500.12556/RUL-97550
• Datum objave v RUL: 26.10.2017

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Simulation of the Three Mile Island nuclear power plant scenario for the case for two loop power plant

Izvleček

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.

• Ključne besede: pressurized water reactor, nuclear power plant simulator, Three Mile Island nuclear power plant, safety