Assessment of the adequacy of RELAP5 system code for the simulation of IBLOCA transient scenarios for Pressurized Water Nuclear Reactors
Tutor / directorFreixa Terradas, Jordi
Document typeMaster thesis
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The assessment of the tools used for deterministic safety analysis and the compliance with the acceptance criteria in thermal-hydraulic analysis of Nuclear Power Plants (NPP) is based on three steps; the first is based on fundamental tests, the second is based on separate effects tests, and the last is about system behaviour phenomena given in integral test facilities. System codes like Reactor Excursion and Leak Analysis Program 5 (RELAP5) are used to simulate the behaviour of NPP under accidental situations. These codes need to fulfil the three steps mentioned before, and with the experimentation on separate effects, local phenomena and integral behaviour, it is possible to validate system codes. This master thesis deals with the third step of the validation process by making use of two experiments, the Light Pressure Water Reactor (LWPR) Off-normal Behaviour Investigation (LOBI) Biblis1-44 (BL-44) and Advanced Thermal-hydraulic Test Loop for Accident (ATLAS) Simulation International Standard Problem 50 (ISP-50). Both are classified as Intermediate Break Loss of Coolant Accident (IBLOCA) scenario. They are used in this thesis to analyse RELAP5 accuracy to reproduce the phenomena within the experiments. This document begins with the introduction of the thesis and the experiments used in order to assess RELAP5. The next section presents the main targets necessary to assess RELAP5 with regarding the IBLOCA scenario as it is a very important scenario in a nuclear safety analysis. Then it follows an explanation of the phenomena taking place in an IBLOCA scenario. The following two chapters are devoted to analysing the LOBI BL-44 and ATLAS ISP-50 main phenomena with the experimental and calculated data with RELAP5. The last chapter, before the conclusions, is dedicated to a combined assessment of phenomena used to analyse RELAP5 capability to reproduce the phenomenology within both experiments. The aim is to reproduce the phenomena within mentioned experiments and to assess whether the RELAP5 system code has reproduced the phenomena successfully. The overall outcome shows that RELAP5 reproduced most of the those adequately within both tests, with these results it was possible to assess the accuracy of RELAP5 enabling it to be used in IBLOCA scenario in actual NPP.
DegreeMÀSTER UNIVERSITARI EN ENGINYERIA NUCLEAR (Pla 2012)