A time-dependent emission of some radionuclides from overheated nuclear fuel

The physico-chemical characteristics of partieles emitted by an overheated nuclear fuel may be significantly modified when they are put in contact with an oxidizing atmosphere at temperatures of the order of 700–900°C. This so-called “maturation” stage induces reactions between radioelements and the UO_x matrix of the acrosol particles. These reactions, in turn, deeply influence the solubility of radioelements in the environment. This paper presents experiments aimed at describing the behavior of characteristic radioactive elements present in nuclear fuel (Cs, Sr, Tb), which are emitted as a consequence of an accidental thermal excursion. As the sequence of radionuclide emission from the nuclear fuel depends on the volatility of their chemical forms, it has to be expected that the maturation stage itself is a time-dependent process in the sequence of emission events.