The paper deals with the activity performed at University of Pisa in the framework of the participation at the Phase II and III of the BEMUSE (Best Estimate Methods – Uncertainty and Sensitivity Evaluation) Programme. The scope of the Programme is to perform Large Break Loss-Of-Coolant Accident analyses making reference to experimental data and to a Nuclear Power Plant in order to address the issue of “the capabilities of computational tools” including scaling/uncertainty analysis. The Phase II of BEMUSE Programme is connected with the re-analysis of the Experiment L2-5 performed in the LOFT facility. Relap5/Mod3.2 has been used to simulate this experiment and the standard procedure adopted at University of Pisa has been applied to obtain a “ qualified nodalization” of the facility through a systematic qualitative and quantitative accuracy evaluation. The qualitative accuracy evaluation is based on the selection of Relevant Thermalhydraulic Aspects (RT As) and is a prerequisite to the application of the Fast Fourier Transform Based Method (FFT BM) which quantifies the error in code predictions related to the measured experimental signals. Several sensitivity analyses have also been performed to study the influence of different parameters (break area, gap conductivity, core pressure drops, time of scram etc.) upon the predicted transient evolution. Finally, the Code with the capability of Internal Assessment of Uncertainty (CIAU) has been used to perform the uncertainty evaluation of the L2-5 test calculation.
Relap5/mod3.2 post-test analysis and CIAU uncertainty evaluation of LOFT experiment L2-5
D'AURIA, FRANCESCO SAVERIO
2005-01-01
Abstract
The paper deals with the activity performed at University of Pisa in the framework of the participation at the Phase II and III of the BEMUSE (Best Estimate Methods – Uncertainty and Sensitivity Evaluation) Programme. The scope of the Programme is to perform Large Break Loss-Of-Coolant Accident analyses making reference to experimental data and to a Nuclear Power Plant in order to address the issue of “the capabilities of computational tools” including scaling/uncertainty analysis. The Phase II of BEMUSE Programme is connected with the re-analysis of the Experiment L2-5 performed in the LOFT facility. Relap5/Mod3.2 has been used to simulate this experiment and the standard procedure adopted at University of Pisa has been applied to obtain a “ qualified nodalization” of the facility through a systematic qualitative and quantitative accuracy evaluation. The qualitative accuracy evaluation is based on the selection of Relevant Thermalhydraulic Aspects (RT As) and is a prerequisite to the application of the Fast Fourier Transform Based Method (FFT BM) which quantifies the error in code predictions related to the measured experimental signals. Several sensitivity analyses have also been performed to study the influence of different parameters (break area, gap conductivity, core pressure drops, time of scram etc.) upon the predicted transient evolution. Finally, the Code with the capability of Internal Assessment of Uncertainty (CIAU) has been used to perform the uncertainty evaluation of the L2-5 test calculation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
