Cold Crucible Technology Research Articles

A use of prototypic material for the investigation of severe accident progression

An experimental research platform using corium melts is established for the understanding of safety related important phenomena during a severe accident progression. The research platform includes TROI facility for corium water interaction experiments and VESTA facility for corium-structural material interaction experiments. A cold crucible technology is adapted and improved for a generation of 5–100 kg of corium melts at various compositions. TROI facility is used for experiments to investigate premixing and explosion behaviors during a fuel coolant interaction process. More than 70 experiments using corium at various compositions were performed to simulate steam explosion phenomena in a reactor situation. The results indicate that the conversion efficiency of steam explosion for corium is less than 1%. VESTA facility is used to investigate molten corium-structural material interaction phenomena. VESTA facility consists of two cold crucibles. One crucible is used for the melting of charged material and pouring of corium melt. The other crucible is used for the corium-structural material interaction while providing an induction heating to simulate the decay heat. The results of an experiment on the interaction between corium melt and a specimen made of Inconel performed in the VESTA facility is reported.

Electromagnetic Cold Crucible Technology Applied for Producing Big-Sized γ-TiAl Based Ingots with Directional Growth Structure

Developing high performance aero-engines usually depends on the development of new candidate materials with charming properties such as relatively light-weight, good high temperature strength and environmental resistance. Fortunately, γ-TiAl alloys were followed into this catalogue that they offer a significant potentiality for weight savings. Recently, in order to improve their low room temperature plasticity, a motive technology called electromagnetic cold crucible directional solidification technology for preparation γ-TiAl alloy ingots with directional growth structure was put forward by our group. By the approach, TiAl ingots with controllable lamellar structures and less impurity contaminations are obtained. Typically, Ti-46Al-0.5W-0.5Si and Ti-47Al-2Cr-2Nb were performed with respect to compositions and solidification parameters. As a result, Ti-46Al-0.5W-0.5Si DS-samples exhibit good combination of mechanical properties at room temperature in TS of 500MPa and EL of 2% in average. Meanwhile TS of DS Ti-47Al-2Cr-2Nb reaches 650 MPa and EL exceeds 3%.

Numerical Simulation of Vitrification Processes: Glass Homogeneity by Gas Bubbling Study

A direct induction process using the cold crucible technology has been developed by the French Atomic Commission and AREVA-NC for 25 years. In this process, walls of the crucible are cooled by internal water circulation which protect them from the corrosion and allow higher temperature of the molten glass. Moreover, a mechanical stirrer and air bubbling system promote a good homogeneity of the melt. This study describes how the air bubbling in the glass is modelled in our simulation and enlightens his important role in the homogenisation of the glass during his elaboration. Air bubbling in liquids as viscous as the glass (viscosity up to 10Pa.s) is not common and specific models have to be built. Two different models are used, first one is a semi-empirical based model, and the second is a two phase model (VOF).

Electric conductivity measurement of oxides melts

Notwithstanding on variety of existing processes of induction skull melting of oxides, electrical and thermal properties of oxides melts are practically unknown. From the other hand, liquid-phase synthesis of Hi-Tech oxides materials such as new ceramics, monocrystals and glasses, requires knowledge of melts properties up to 3700 K. Inasmuch as the main physical property, which influence to the melt power consumption at induction heating is electrical conductivity then study of electrical conductivity temperature dependence is necessary. The principle and technical realization of the electrical conductivity measurement of melts are presented. The approach is based on induction melting in cold crucible technology and inverse electromagnetic problem solution. Analysis of the method accuracy via input data errors is presented. For increasing of Ill-posed problem solution was used over determination of set of equations. Conductivity of aluminum oxide melts for the temperature up to 3223 K is shown too.

ICONE15-10814 PROSPECTIVE APPLICATIONS OF THE METALLIC COLD CRUCIBLE TECHNOLOGY FOR THE VITRIFICATION OF VARIOUS WASTES

This paper presents a review of the CCIM (Cold Crucible Induction Melter) technology development as led by CEA and gives recent illustrations of prospective applications of a metallic cold crucible technology for various waste treatments obtained with research full scale pilot devices.

Directional solidification of titanium alloys by electromagnetic confinement in cold crucible

In order to suppress the reactivity of titanium alloys and modify their structures into directionality, a new solidification method in which its process is continuity of induction melting, electromagnetic confinement and propelling cooling effect is proposed for casting Ti–6Al–4V alloy directionally based on the cold crucible technology. Due to an incomplete contact of the titanium melt with the inner wall of cold crucible with respect to the results of electromagnetic confinement, heat transfer coefficient becomes lower through the melt/crucible interface than that in the conventional casting method. By defining a contact ratio of k c, the comparison of the heat transfer phenomena in cold crucible with or without electromagnetic effect is taken into account to understand the experimental results to some extent. It is revealed that the solidified front is always convex upward in the periphery areas of the specimens and, in the inner growing zones, the contours of the front will descend from convexity upward to concavity downward with the withdrawal velocities increased. Thus, with slowing down the growth rate, the grain numbers will decrease to a small extent and as shown in this experimental, a single grain has been obtained when the velocity attains 0.5 mm/min. Tensile test shows that directional solidifying ingots have a higher tensile strength and elongation than that without directional structures.

Steam Explosion Experiments using ZrO$_2$

Korea Atomic Energy Research Institute (KAERI) launched an intermediate scale steam explosion experiment named Test for Real Corium Interaction with water (TROI) using reactor material to investigate whether the molten reactor material would lead to energetic steam explosion when interacted wish cold water at low pressure. The melt-water interaction experiment is performed in a pressure vessel with the multi-dimensional fuel and water pool geometry. The novel concept of cold crucible technology, where powder of the reactor material in a water-cooled cafe is heated by high frequency induction, is firstly implemented for the generation of molten fuel. In this paper, the lest facility and cold crucible technology are introduced and the results or the first series of tests were discussed. The 5 kg of molten ZrOjet was poured into the 67cm deep water pool at 30 ∼ 95 . Either spontaneous steam explosions or quenching was observed. The morphology of debris and pressure wave profiles clearly indicate the differences between the two cases.

Comparative Study of Synroc-C Ceramics Produced by Hot-Pressing and Inductive Melting

ABSTRACTThree Synroc-C samples, containing simulated high level waste were studied. One was produced by the conventional hot-pressing method at ANSTO, Australia, and the others were obtained using cold crucible technology at Radon, Russia. One of the melted samples was prepared using the Australian sol-gel precursor and the second one was obtained from an oxide-nitrate mixture. It was established that the specimens have closely similar mineral compositions, with major hollandite, perovskite, zirconolite, and rutile. Small amounts of hibonite were also found. Unlike the hot-pressed Synroc containing metallic alloy particles, melted Synrocs contain molybdates. An investigation of mineral compositions and elemental distribution in the samples was carried out. Features of hot-pressed and melted ceramics were compared. Unit cell parameters of the Synroc phases were determined and preliminary results on durability of the melted Synroc are presented.

Some Applications of Cold Crucible Technology for Silicon Photovoltaic Material Preparation

Cold crucible melt confinement was used for four different silicon crystallization methods of interest in photovoltaic material preparation: directional solidification, Czochralski pulling, sheet growth, and continuous ingot casting. Large grained, multicrystalline ingots were directionally solidified in cold crucibles, and grain sizes up to 5 mm were observed. Dislocation‐free crystals were pulled in [111] and [100] orientations, using semiconductor‐grade silicon. The edge‐supported pulling (ESP) growth method was employed for sheet growth. The sheets were solidified between quartz filaments. Continuous casting of square cross‐sectional ingots with grain sizes of up to several millimeters was carried out. Material suitable for fabrication into solar cells was obtained by these methods. AM1 solar cell IV characteristics are presented for the different materials and for coprocessed cells made from conventional Czochralski crystals grown using quartz crucibles. Some purity and electrical property data for cold crucible crystals are also given. Dislocation‐free cold crucible crystals had higher purity levels and photovoltaic conversion efficiencies than conventional Czochralski crystals.