Material characterization of the VULCANO corium concrete interaction test with concrete representative of Fukushima Daiichi Nuclear Plants

TAF-ID: An international thermodynamic database for nuclear fuels applications

“…New measurements would be needed to form a more definitive understanding. Calculations are performed on: i) well controlled heat treatments of (UO2-ZrO2) / (SiO2-CaO-Al2O3) compositions with two CaO and SiO2 rich concrete compositions [53], and ii) VULCANO corium concrete interaction test VF-U1 with concrete representative of Fukushima Daiichi Nuclear Plants [54].…”

“…Al2O3 -6 Fe2O3 in w. %) section under air. The interaction occurred for 15 minutes with an initial temperature of about 2200 K. The microstructure of the solidified corium pool (sample 4 in [54]) is…”

“…The microstructure is constituted of a silicon rich matrix, zirconium and uranium rich zones as well as iron rich regions. Thermodynamic calculations were performed at 2190 K using the overall composition of sample 4 measured by Energy Dispersive Spectroscopy (EDS; given in Table 2 in [54]). At 2190 K, the phases predicted to form from the calculations are:…”

“…% of (Zr0.8U0.15Ca0.05)O2; this phase could correspond to the observed large size ZRO (Zirconium Rich Object) or CRN regions. In [54], these regions were found to be heterogeneous with a high zirconium rich oxide ((Zr0.93U0.07)O2) at the center whereby content decreases towards the edge, up to an average composition (U0.5Zr0.5)O2 having a two-phase microstructure containing a mixture of U and Zr rich mixed oxides and a small 25 amount of minor elements (i.e., Si, Ca, Al, …). The calculations show that during cooling, the mixed oxide (Zr0.8U0.15Ca0.05)O2 decomposes into several cubic and tetragonal mixed oxides with different Zr/U ratios, which could explain the presence of these oxide phases with different compositions.…”

Ten years after the NPP accident at Fukushima : review on fuel debris behavior in contact with water

“…It can accumulate at the pedestal bottom and encompass previously present structures [4,24]. Eventually, it can interact with concrete leading to mixing with the basaltic concrete decomposition products: SiO 2 , CaO, MgO,Al 2 O 3 , rebar steel, oxygen (from concrete water content) [19,25,26]. Figure 2b and 2c present some prototypic MCCI debris blocks manufactured in COLIMA [24] and VULCANO facilities [26] with BWR-representative compositions.…”