1,721,133 research outputs found
Corium Spreading and Coolability (CSC Project)
No full textIn the context of severe accidents, large R&D efforts throughout the world are currently directed towards ex-vessel corium behaviour. Among the mitigation means which can be envisaged, the European industries and utilities are considering the implementation of a core-catcher outside the reactor pressure vessel in order to prevent basemat erosion and to stabilize and control the corium within the containment. The CSC project focused on two key phenomena for external core-catcher efficiency, reliability and safety : spreading and coolability. An experimental programme, covering different scenarios and including both simulant and real materials provided a lot of results which constitute now a large database and which enabled the qualification of 2 computer codes. After a brief presentation of the project, this paper presents the results obtained
Corium Spreading Phenomena: Results obtained from the UE CSC Project
No full textIn the context of severe accidents, large R&D efforts throughout the world are currently directed towards ex-vessel corium behaviour. Among the mitigation means which can be envisaged, the European industries and utilities are considering the implementation of a core-catcher outside the reactor pressure vessel in order to prevent basemat erosion and to stabilize and control the corium within the containment. The CSC project focused on two key phenomena for external core-catcher efficiency, reliability and safety : spreading and coolability. An experimental programme, covering different scenarios and including both simulant and real materials provided a lot of results which constitute now a large database and which enabled the qualification of 2 computer codes. After a brief presentation of the project, this paper presents the results obtained
Assessment of THEMA Code against Spreading Experiments
No full textIn the frame work of Severe Accident research, the spreading code THEMA, developed at CEA/DRN, aims at predicting the spreading extent of molten core after a vessel melt-through. The code solves fluid balance equations integrated over the fluid depth for oxidic and/or metallic phases under the shallow water assumption, using a finite difference scheme. Solidification is taken into account through crust formation on the substrate and at contact with the surroundings, as well as increase of fluid viscosity with solid fraction in the melt. A separate energy equation is solved for the solid substrate, including possible ablation. The assessment of THEMA code against the spreading experiments performed in the framework of the Corium Spreading and Coolability project of the European Union is presented. These experiments use either simulating materials at medium (RIT), or at high temperature (KATS), or corium (VULCANO, FARO), conducted at different mass flow rates and with large or low solidification interval. THEMA appears to be able to simulate the whole set of the experiments investigated. Comparison between experimental and computed spreading lengths and substrate temperatures are quite satisfactory. The results show a rather a rather large sensitivity at mass flow rate and inlet temperature, indicating that, generally, efforts should be made to improve the accuracy of the measurements of such parameters in the experiments
CSC Project, Task 1.4.2: ENEA's Final Report
No full textIn the event of a highly unlikely core melt-down accident, scenarios with reactor pressure vessel failure and corium ( a mixture of UO2, ZrO2, Zr, Fe and fission products) relocation into the reactor cavity cannot be excluded. In this context large R&D efforts are directed towards ex-vessel corium behaviour, in particular on long-term corium retention and coolability within the containment. The two generic processes spreading of the corium under various initial and boundary conditions and cooling of the melt by direct water contact are the main issues addressed by the Corium Spreading and Coolability (CSC) Project. ENEA is a partner of CSC Project and contributes to the development and qualification of the THEMA Code in a very near cooperation with CEA and EdF. THEMA code is available through the CEA-ENEA cooperation agreement on future reactors. Hereunder there is a concise outline of ENEA performed work in the framework of CSC Project
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