Physico-chemical properties of Chernobyl lava and their destruction products

Synthesis, characterisation and corrosion behaviour of simulant Chernobyl nuclear meltdown materials

“…The samples became liquid at temperatures of >1213 ± 5°C, and heating to 1280 ± 5°C and 1359 ± 5°C was required to obtain a crystal-free melt for simulant Brown and Black LFCM, respectively. This is somewhat lower than the estimations of the melt temperature of LFCM within the Chernobyl reactor, which range between 1400°C and 1550°C, 2,17 and may be explained by the compositional heterogeneity of LFCM. Other than the exclusion of fission products, the primary difference in composition between the real LFCM and the simulant materials analysed here is the source of Zr.…”

“…The incorporation of~5 wt% and 10 wt% U in zircon from simulated Black and Brown lavas is in good agreement with literature values (5.6 wt% and 11.3 wt%, respectively). 17 At the centre of several of the zircon crystals, small Zr-bearing inclusions were observed (e.g., Fig. 3c).…”

“…The presence of albite (NaAlSi 3 O 8 ), as large dendrites within the glassy matrix, is in accordance with previous observations of pyroxenelike minerals with a composition of (Ca 0.08 Fe 0.02 Cr 0.02 Zr 0.02 ) Al 0.18 Mg 1.86 Si 1.82 O 5.97 , in particles of real LFCM. 17 Thermal analysis of simulant LFCM, as determined by DTA, gave values for T g of 722 ± 5°C and 732 ± 5°C for the Brown and Black compositions, respectively (Table 1; Supplementary Fig. 2).…”

“…(Zr 1-x U x ) O 2 ) had a cubo-octahedral, fused, or dendritic morphology, consistent with textures observed in real LFCM. 1,11,17 Furthermore, spherical inclusions containing Fe, Cr, Ni and Mo were observed, arising from the addition of stainless steel to the samples prior to thermal treatment ( Supplementary Fig. 1).…”

“…Samples of the material are limited due to the difficulties and dangers associated with their collection (unstable building, high radiation levels), and only a few specimens of the lava that were sampled from within the reactor building have been studied. Despite recent studies, 9,17,18 little is known about the condition of Chernobyl LFCM, especially now, 33 years after the accident. To overcome this lack of information, past attempts to simulate lowactivity LFCMs (i.e., containing no fission products, only depleted uranium) have been made to help understand the conditions within the reactor during the accident, however, this work was unable to accurately approximate the microstructure, morphology and mineralogy of LFCM.…”