Ex-Vessel Corium Cooling: From PIRT to Accident Management
Open for Proposals
Project Type
Coordinated Research ProjectProject Code
I31042
CRP
2424
Approved Date
2025.12.03Project Status
New - Collecting or Evaluating proposalsDescription
This CRP aims to harmonise international understanding of ex-vessel corium behaviour and cooling (EVCC) during severe accidents in water-cooled reactors. It will consolidate available data from experiments and from Chernobyl and Fukushima accident examinations, enhance modelling and simulation, conduct benchmark exercises including accident management scenarios, and develop training resources for capacity building. Motivated by key IAEA meetings and reinforced by expert input from leading research institutes and national programmes, the CRP addresses a high-priority R&D topic with strong Member State support. By providing a harmonised technical basis, it will support accident management strategies across diverse reactor designs.
Objectives
(1) To enhance international understanding and predictive capabilities related to ex-vessel corium behaviour and cooling (EVCC) during severe accidents in water-cooled reactors, by fostering coordinated research, data assessment, model development, benchmarking, and the creation of training resources. This CRP will support harmonised safety assessments and inform effective accident management strategies across a range of reactor types and Member States.
(2) Harmonised understanding of EVCC phenomena: Develop a structured and consensus-based Phenomena Identification and Ranking Table (PIRT) relevant to ex-vessel corium behaviour, including those related to melt relocation, melt spreading, MCCI, debris bed formation and cooling, and containment integrity. Focus will be on the impact of accident management.
(3) Consolidated experimental and plant data for model validation: Compile, assess, and indicate the relevance of publicly available open-access experimental and data, as well as open data from Chernobyl and Fukushima accident examinations; identify needs in data coverage with particular attention to accident management and evaluate the applicability of data to reactor-scale scenarios and modelling validation.
(4) Improved modelling capabilities: Support exchange of modelling strategies, uncertainty quantification approaches, AI/ML techniques, and documentation of key assumptions and code inputs with the goal of improving the common understanding of key phenomena relevant to EVCC.
(5) Coordinated benchmarking on key EVCC scenarios and accident management measures: Design and implement a series of coordinated benchmark exercises using selected datasets. Conduct an integrated benchmark based on an accident scenario taking into account Fukushima accident progression, combining multiple phenomena and allowing for sensitivity analyses. Include benchmark scenarios specifically assessing the ability of codes to evaluate the effect of accident management measures.
(6) Training and capacity building: Promote and support Member States participation in the CRP, especially from developing and newcomer countries, and encourage knowledge transfer.