Modelling of the PWR PACTEL vertical steam generator with the TRACE code

The behavior of the nuclear power plants must be known in all operational situations. Thermal hydraulics computer applications are used to simulate the behavior of the plants. The computer applications must be validated before they can be used reliably. The simulation results are compared against the experimental results. In this thesis a model of the PWR PACTEL steam generator was prepared with the TRAC/RELAP Advanced Computational Engine computer application. The simulation results can be compared against the results of the Advanced Process Simulator analysis software in future. Development of the model of the PWR PACTEL vertical steam generator is introduced in this thesis. Loss of feedwater transient simulation examples were carried out with the model.

Kevytvesireaktorin luonnonkierto ja stabiilius

Tässä työssä perehdytään luonnonkiertoon ja sen hyödyntämiseen ydinvoimalaitoksissa. Toisena aihekokonaisuutena työssä ovat ydinvoimalaitosten epästabiilit tilat, jotka ovat tyypillisiä etenkin luonnonkierron ja kaksifaasivirtauksen yhteydessä. Lopussa esitetään ydinvoimalaitoksen termohydrauliikan ja kaksifaasivirtauksen mallinnusta systeemikoo-deilla. Esimerkkinä on tehty laskenta luonnonkiertoreaktorin, ESBWR-reaktorin massavirran jakaumasta TRACE-systeemikoodilla.

Scaling analysis of small break experiments in PACTEL

The purpose of this thesis is to study the scalability of small break LOCA experiments. The study is performed on the experimental data, as well as on the results of thermal hydraulic computation performed on TRACE code. The SBLOCA experiments were performed on PACTEL facility situated at LUT. The temporal scaling of the results was done by relating the total coolant mass in the system with the initial break mass flow and using the quotient to scale the experiment time. The results showed many similarities in the behaviour of pressure and break mass flow between the experiments.