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Brissonneau, L.*; 池内 宏知; Piluso, P.*; Gousseau, J.*; David, C.*; Testud, V.*; Roger, J.*; Bouyer, V.*; 北垣 徹; 仲吉 彬; et al.
Journal of Nuclear Materials, 528, p.151860_1 - 151860_18, 2020/01
被引用回数：15 パーセンタイル：86.19(Materials Science, Multidisciplinary)In the framework of JAEA-CEA collaboration, experimental studies have been conducted for estimating the material characteristics of corium debris representative of the Fukushima Daiichi nuclear damaged plants. A test has been performed in the VULCANO facility in CEA Cadarache to simulate the concrete corium interaction (CCI) with prototypic corium (using depleted uranium) and concrete of Fukushima Daiichi 1F1 Nuclear Plant. This paper presents the Post Test Analyses on 9 samples representative of the CCI during this test: in the corium pool, in the crusts and at the vertical and horizontal interfaces with the concrete. Analyses have been performed by SEM/EDS, X-Ray Diffraction, complete dissolution and ICP, micro-hardness measurements of the main phases. The major phases encountered are uranium rich and zirconium rich oxides forming nodules from micrometers to millimeters size, chromium-iron rich precipitates of several micrometers, metallic Fe-Ni droplets and chromium-silicon rich filaments in a matrix, likely vitreous, rich in concrete elements: Si, Al, Ca, but containing up to 12 cations. The matrix is the softer oxide phase, when the Cr rich precipitates are the harder. The analyses are consistent with the estimated macroscopic ablation ratio, but do not still explain the important axial ablation observed for this specific basaltic concrete. The different phases formation, distribution and solidification path are discussed. First comparisons are proposed with the former CCI tests with European concretes. These results give helpful insights for the future dismantling of the plant and for a deeper understanding of the CCI process for basaltic concrete.
仲吉 彬; 池内 宏知; 北垣 徹; 鷲谷 忠博; Bouyer, V.*; Journeau, C.*; Piluso, P.*; Excoffier, E.*; David, C.*; Testud, V.*
Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05
A large-scale Molten Core-Concrete Interaction (MCCI) test (VF-U1) under the Fukushima Daiichi Nuclear Power Station (1F) conditions (core material composition, concrete, and decay heat) was conducted at the large MCCI test facility (VULCANO) owned by French Alternative Energies and Atomic Energy Commission (CEA) in France. About 50 kg of simulated debris was melted and brought into contact with concrete to erode concrete under 1F conditions. After cooling, the concrete test section (concrete and MCCI product) was dismantled. Main observations of the structure of solidified pool (crust, porosity, oxide/metal layer, etc.) and of the ablation are given. The technical results obtained herein are summarized, and they provide interesting knowledge that will help with the decommissioning of 1F.
Bouyer, V.*; Journeau, C.*; Haquet, J. F.*; Piluso, P.*; 仲吉 彬; 池内 宏知; 鷲谷 忠博; 北垣 徹
Proceedings of 9th Conference on Severe Accident Research (ERMSAR 2019) (Internet), 13 Pages, 2019/03
Fuel debris removal is one of the most important processes for decommissioning a severely damaged nuclear power plant (NPP) such as Fukushima Daiichi NPP (1F). In order to develop relevant removal tools, characteristics of fuel debris are required. In the frame of a JAEA-CEA cooperation, a large-scale MCCI test was performed at the CEA/VULCANO facility using a prototypic metal and oxide corium representative from Fukushima Daiichi unit 1 conditions. Conclusions arising from the material analysis of the selected samples will be relevant for future dismantling operations. This paper deals with the experimental device and process, objective and initial conditions of this MCCI test, and ablation of the concrete quantified in term of volume, depths and velocities. The test section concrete, made with Japanese components, is siliceous with basaltic origin. The main objective of the test was to get a significant ablation leading to an ablation volume ratio of 1.6 in order to produce fuel debris with a composition corresponding to expected conditions in the damaged plant. On a phenomenological point of view, it must be noted that the concrete ablation was clearly anisotropic with a predominantly downwards ablation contrary to previous experiments with silica and limestone concrete.
Brissonneau, L.*; Gousseau, J.*; Piluso, P.*; Bouyer, V.*; 北垣 徹; 池内 宏知; 矢野 公彦; 鷲谷 忠博
no journal, ,
In case of severe accident in a nuclear reactor, the mixture obtained from fuel core and pins (mainly UO
and zirconium), called corium, can penetrate the steel vessel and interact with the concrete, as in the Fukushima Daiichi NPP (1F) severe accidents. A specific test has been realized with a concrete similar to the one of the Fukushima Daiichi NPP (1F) and an "oxide metal" corium. Ten samples were collected from representative places (corium core, crust, vertical and horizontal interfaces) and examined by SEM and XRD. The talk will present some of the main features of the solids formed after CCI.
