The Phébus FP experimental campaign (1988 - 2010) is recognized as one of the most relevant in the field of Severe Accident researches. During this international research programme, 4 tests were performed to investigate the degradation phenomena for a real PWR fuel bundle in strongly or weakly oxidizing conditions, considering different control rod materials and burn-up levels, plus 1 test studying the phenomena related to a melt pool scenario. These integral tests gave a fundamental improvement in the knowledge of the key phenomena occurring during a Severe Accident and the obtained data were also employed to develop numerical models for the safety analysis of these scenarios. The ASTEC and the MELCOR integral codes were two of the main international codes that have benefited from these experimental data. After the termination of the Phébus FP campaign, these two codes were furthermore improved, implementing more recent research findings. So, a continuous verification and validation work is necessary to check that the new improvements, implemented in such codes, also allow a better prediction of these past Phébus FP tests. Therefore, the aim of the present work is to re-analyze the Phébus FPT-3 test employing the up-to-date versions of the ASTEC and MELCOR codes. This FPT-3 test was also the basis for an international benchmark exercise carried out in the frame of the EU SARNET project. The performed analysis focuses only on the stand-alone containment aspects of the test and a comparison against the results obtained by the different participants to the SARNET benchmark is also performed. An original analysis on the main differences obtained employing three different spatial nodalizations and a sensitivity analysis on the effects of different input parameters influencing the aerosol behavior are also proposed. These sensitivity analyses also show the need of a sufficient number of volumes for a correct prediction of the coupling between the containment thermal-hydraulics transient and the aerosol behavior. The results obtained show only a partial agreement with the experimental data and with the best calculations performed during the SARNET benchmark, due to the presence of user’s effects.
Stand-alone containment analysis of the Phébus FPT-3 test with the ASTEC and the MELCOR codes
Bruno Gonfiotti
;Sandro Paci
2018-01-01
Abstract
The Phébus FP experimental campaign (1988 - 2010) is recognized as one of the most relevant in the field of Severe Accident researches. During this international research programme, 4 tests were performed to investigate the degradation phenomena for a real PWR fuel bundle in strongly or weakly oxidizing conditions, considering different control rod materials and burn-up levels, plus 1 test studying the phenomena related to a melt pool scenario. These integral tests gave a fundamental improvement in the knowledge of the key phenomena occurring during a Severe Accident and the obtained data were also employed to develop numerical models for the safety analysis of these scenarios. The ASTEC and the MELCOR integral codes were two of the main international codes that have benefited from these experimental data. After the termination of the Phébus FP campaign, these two codes were furthermore improved, implementing more recent research findings. So, a continuous verification and validation work is necessary to check that the new improvements, implemented in such codes, also allow a better prediction of these past Phébus FP tests. Therefore, the aim of the present work is to re-analyze the Phébus FPT-3 test employing the up-to-date versions of the ASTEC and MELCOR codes. This FPT-3 test was also the basis for an international benchmark exercise carried out in the frame of the EU SARNET project. The performed analysis focuses only on the stand-alone containment aspects of the test and a comparison against the results obtained by the different participants to the SARNET benchmark is also performed. An original analysis on the main differences obtained employing three different spatial nodalizations and a sensitivity analysis on the effects of different input parameters influencing the aerosol behavior are also proposed. These sensitivity analyses also show the need of a sufficient number of volumes for a correct prediction of the coupling between the containment thermal-hydraulics transient and the aerosol behavior. The results obtained show only a partial agreement with the experimental data and with the best calculations performed during the SARNET benchmark, due to the presence of user’s effects.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
