In the framework of the In Vessel Melt Retention (IVMR) project, coordinated by IRSN, funded by Horizon 2020 Framework Programme of the European Commission and started in June 2015, ENEA is involved in the development of a generic PWR-900 analyses with MELCOR 2.2 code for benchmarking ASTEC code in relation to the phenomenology taking place when In Vessel Retention (IVR) strategy is applied. The IVR strategy for LWR is based on external reactor vessel cooling, by water flooding of the reactor cavity before vessel failure, aiming to avoid lower head failure and maintain the corium in the RPV. The severe accident scenario selected for this MELCOR 2.2 analyses with IVR application is an unmitigated Station Blackout (SBO). The target of this paper is to present the analyses of the main figure of merits related to this kind of transient (e.g. primary pressure, max intact cladding temperature, hydrogen production, zircaloy fraction oxidized, etc) and the corium degradation evolution. Particular attention will be focused on the characterization of the corium composition behaviour in the lower plenum and the consequent lower head thermal attack (e.g. axial profile along the lower head wall) that, through selected figure of merits (e.g. corium physical characteristics in the LP, maximum heat flux along the LH wall) will be compared also with the results obtained by ENEA_ASTEC calculation to show the differences between the codes due to the uncertainties on core degraded configurations implemented in severe accident codes and on the way the core relocates to the LH

Analyses with MELCOR code of an unmitigated SBO scenario with in vessel retention strategy applied to a generic PWR 900 MWe

Mascari, F.;Ederli, S
2019

Abstract

In the framework of the In Vessel Melt Retention (IVMR) project, coordinated by IRSN, funded by Horizon 2020 Framework Programme of the European Commission and started in June 2015, ENEA is involved in the development of a generic PWR-900 analyses with MELCOR 2.2 code for benchmarking ASTEC code in relation to the phenomenology taking place when In Vessel Retention (IVR) strategy is applied. The IVR strategy for LWR is based on external reactor vessel cooling, by water flooding of the reactor cavity before vessel failure, aiming to avoid lower head failure and maintain the corium in the RPV. The severe accident scenario selected for this MELCOR 2.2 analyses with IVR application is an unmitigated Station Blackout (SBO). The target of this paper is to present the analyses of the main figure of merits related to this kind of transient (e.g. primary pressure, max intact cladding temperature, hydrogen production, zircaloy fraction oxidized, etc) and the corium degradation evolution. Particular attention will be focused on the characterization of the corium composition behaviour in the lower plenum and the consequent lower head thermal attack (e.g. axial profile along the lower head wall) that, through selected figure of merits (e.g. corium physical characteristics in the LP, maximum heat flux along the LH wall) will be compared also with the results obtained by ENEA_ASTEC calculation to show the differences between the codes due to the uncertainties on core degraded configurations implemented in severe accident codes and on the way the core relocates to the LH
ASTEC, Corium behaviour in the lower plenum, IVR, MELCOR, Severe accident
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12079/54499
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