Secondary uranium minerals on the surface of Chernobyl ''lava''

The formation of uranium minerals is still continuing in Chernobyl Unit No. 4. Yellow products of alteration that stain the surface of Chernobyl ''lava'' have been examined by SEM and X-ray diffraction methods. Secondary minerals of uranium identified are: UO4 . 4H(2)O studtite; UO3 . 2H(2)O epiianthinite; UO2 . CO3, rutherfordine; also, Na-4(UO2)(CO3)(3) was identified together with the sodium carbonate phases Na3H(CO3)(2) . 2H(2)O and Na2CO3 . H2O. These minerals formed due to the interaction between fuel-containing masses or ''lava'', water and air. The matrices of the ''lava'' do not contain significant amounts of sodium. The source of sodium may be water that has penetrated into the ''Sarcophagus''. All identified secondary minerals of uranium are highly unstable, and their continued formation can seriously endanger the radiological situation of the 4(th) Unit.